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Sample records for behavior surface properties

  1. 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.

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

    International Nuclear Information System (INIS)

    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.

  3. Transformation behavior and mechanical properties of an equiatomic Ti-Ni alloy with surface sulfide layers

    Energy Technology Data Exchange (ETDEWEB)

    Nam, T.H.; Park, S.M.; Cho, G.B. [Information Technology Research Center for Energy Storage and Conversion, Gyeongsang National Univ., Jinju, Gyeongnam (Korea)

    2005-07-01

    Surface sulfide layers were formed on the surface of Ti-50.0(at%)Ni alloys by isothermal annealing at 873 K for 3.6 ks under the sulfur pressure of 80 kPa, and then transformation behavior and mechanical properties were investigated by means of differential scanning calorimetery(DSC), thermal cycling tests under constant load, and tensile tests. The DSC peaks were broadened and martensitic transformation start temperature(Ms) increased from 281 K to 289 K by sulfurization. An equiatomic Ti-Ni alloy with surface sulfide layers showed good shape memory characteristics and partial superelasticity. (orig.)

  4. Surface properties and corrosion behavior of Co-Cr alloy fabricated with selective laser melting technique.

    Science.gov (United States)

    Xin, Xian-zhen; Chen, Jie; Xiang, Nan; Wei, Bin

    2013-01-01

    We sought to study the corrosion behavior and surface properties of a commercial cobalt-chromium (Co-Cr) alloy which was fabricated with selective laser melting (SLM) technique. For this purpose, specimens were fabricated using different techniques, such as SLM system and casting methods. Surface hardness testing, microstructure observation, surface analysis using X-ray photoelectron spectroscopy (XPS) and electrochemical corrosion test were carried out to evaluate the corrosion properties and surface properties of the specimens. We found that microstructure of SLM specimens was more homogeneous than that of cast specimens. The mean surface hardness values of SLM and cast specimens were 458.3 and 384.8, respectively; SLM specimens showed higher values than cast ones in hardness. Both specimens exhibited no differences in their electrochemical corrosion properties in the artificial saliva through potentiodynamic curves and EIS, and no significant difference via XPS. Therefore, we concluded that within the scope of this study, SLM-fabricated restorations revealed good surface properties, such as proper hardness, homogeneous microstructure, and also showed sufficient corrosion resistance which could meet the needs of dental clinics. PMID:23553145

  5. Effect of filler surface properties on stress relaxation behavior of carbon nanofiber/polyurethane nanocomposites

    Science.gov (United States)

    Sedat Gunes, I.; Jimenez, Guillermo; Jana, Sadhan

    2009-03-01

    The effect of carbon nanofiber (CNF) surface properties on tensile stress relaxation behavior of CNF/polyurethane (PU) nanocomposites was analyzed. PU was synthesized from methylene diisocyanate, polypropylene glycol (PPG diol), and butanediol. CNF, oxidized CNF (ox-CNF), and PPG diol grafted CNF (ol-CNF) were selected as fillers. ol-CNF was obtained by grafting PPG diol onto ox-CNF by reacting it with the carboxyl groups present on ox-CNF surface. The atomic ratios of oxygen to carbon present on the filler surfaces were 0.13 and 0.18 on ox-CNF and on ol-CNF as compared to 0.015 on CNF, mostly due to the presence oxygen containing polar groups on the surfaces of the former. The composites were prepared by in-situ polymerization and melt mixing in a chaotic mixer. The stress relaxation behavior of composites was determined at room temperature after inducing a tensile strain of 100%. The presence of fillers augmented the rate of stress relaxation in composites which was highest in the presence of CNF. The results suggested that relatively weak polymer-filler interactions in composites of CNF promoted higher stress relaxation.

  6. Influence of particle surface properties on the dielectric behavior of silica/epoxy nanocomposites

    International Nuclear Information System (INIS)

    Silica/epoxy composites have been widely used in functional electric device applications. Silica nanoparticles, both unmodified and modified with the coupling agent KH-550, were used to prepare epoxy composites. Dielectric measurements showed that nanocomposites exhibit a higher dielectric constant than the control sample, and had more obvious dielectric relaxation characteristics. Results showed that particle surface properties have a profound effect on the dielectric behavior of the nanocomposites. These characteristics are attributed to the local ununiformity of the microstructure caused by the large interface area and the interaction between the filler and the matrix. This phenomenon is explained in terms of prolonging chemical chains created during the curing process. The mechanism is discussed with measurements of X-ray diffraction (XRD) and Fourier transform infrared (FTIR)

  7. The relationship between the particle properties, mechanical behavior, and surface roughness of some pharmaceutical excipient compacts

    International Nuclear Information System (INIS)

    Several common pharmaceutical excipient powders were compacted at a constant solid fraction (SF) in order to study the relationship between powder properties, compact surface roughness, and compact mechanical properties such as hardness, elasticity, and brittleness. The materials used in this study included microcrystalline cellulose (MCC), fumaric acid, mannitol, lactose monohydrate, spray dried lactose, sucrose, and dibasic calcium phosphate dihydrate. A slow consolidation process was used to make compacts at a SF of 0.85 (typical for most pharmaceutical tablets) from single excipient components. A model was proposed to describe the surface roughness of compacts based on the brittle or ductile deformation tendencies of the powder materials. The roughness profile would also be dependent upon the magnitude of the compression stress in relation to the yield stress (onset of irreversible deformation) values of the excipients. It was hypothesized that brittle materials would produce smooth compacts with high surface variability due to particle fracture, and the converse would apply for ductile materials. Compact surfaces should be smoother if the materials were compressed above their yield pressure values. Non-contact optical profilometry was used along with scanning electron microscopy to quantify and characterize the surface morphology of the excipient compacts. The roughness parameters Ra (average roughness), Rq (RMS roughness), Rq/Ra (ratio describing surface variability), and Rsk (skewness) were found to correlate with the deformation properties of the excipients. Brittle materials such as lactose, sucrose, and calcium phosphate produced compacts with low values of Ra and Rq, high variability, and negative Rsk. The opposite was found with plastic materials such as MCC, mannitol, and fumaric acid. The highly negative skewness values for brittle material compacts may indicate their propensity to be vulnerable to cracks or surface defects. These findings supported

  8. The relationship between the particle properties, mechanical behavior, and surface roughness of some pharmaceutical excipient compacts

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Padma; Hancock, Bruno C

    2003-08-25

    Several common pharmaceutical excipient powders were compacted at a constant solid fraction (SF) in order to study the relationship between powder properties, compact surface roughness, and compact mechanical properties such as hardness, elasticity, and brittleness. The materials used in this study included microcrystalline cellulose (MCC), fumaric acid, mannitol, lactose monohydrate, spray dried lactose, sucrose, and dibasic calcium phosphate dihydrate. A slow consolidation process was used to make compacts at a SF of 0.85 (typical for most pharmaceutical tablets) from single excipient components. A model was proposed to describe the surface roughness of compacts based on the brittle or ductile deformation tendencies of the powder materials. The roughness profile would also be dependent upon the magnitude of the compression stress in relation to the yield stress (onset of irreversible deformation) values of the excipients. It was hypothesized that brittle materials would produce smooth compacts with high surface variability due to particle fracture, and the converse would apply for ductile materials. Compact surfaces should be smoother if the materials were compressed above their yield pressure values. Non-contact optical profilometry was used along with scanning electron microscopy to quantify and characterize the surface morphology of the excipient compacts. The roughness parameters R{sub a} (average roughness), R{sub q} (RMS roughness), R{sub q}/R{sub a} (ratio describing surface variability), and R{sub sk} (skewness) were found to correlate with the deformation properties of the excipients. Brittle materials such as lactose, sucrose, and calcium phosphate produced compacts with low values of R{sub a} and R{sub q}, high variability, and negative R{sub sk}. The opposite was found with plastic materials such as MCC, mannitol, and fumaric acid. The highly negative skewness values for brittle material compacts may indicate their propensity to be vulnerable to

  9. Surface magnetism Correlation of structural, electronic and chemical properties with magnetic behavior

    CERN Document Server

    Getzlaff, Mathias

    2010-01-01

    This volume reviews on selected aspects related to surface magnetism, a field of extraordinary interest during the last decade. The special emphasis is set to the correlation of structural, electronic and magnetic properties in rare earth metal systems and ferromagnetic transition metals. This is made possible by the combination of electron emission techniques (spin polarized photoelectron spectroscopy, magnetic dichroism in photoemission and spin polarized metastable deexcitation spectroscopy) and local probes with high lateral resolution down to the atomic scale (spin polarized scanning tunneling microscopy / spectroscopy).

  10. Physical and chemical modifications of surface properties lead to alterations in osteoblast behavior

    Science.gov (United States)

    Dorst, Kathryn Elizabeth

    Proper formation of the bone extracellular matrix (ECM), or osteoid, depends on the surface properties of pre-existing tissue and the aqueous chemical environment. Both of these factors greatly influence osteoblast migration, cytoskeletal organization, and calcium nodule production, important aspects when considering the biocompatibility of bone implants. By perturbing the physical and/or chemical micro-environment, it may be possible to elucidate effects on cellular function. To examine these factors, murine pre-osteoblasts (MC3T3-E1 subclones 4 and 24) were seeded on polydimethylsiloxane (PDMS) substrates containing "wide" micro-patterned ridges (20 mum width, 30 mum pitch, & 2 mum height), "narrow" micro-patterned ridges (2 mum width, 10 mum pitch, 2 mum height), no patterns (flat PDMS), and standard tissue culture (TC) polystyrene as a control. Zinc concentration was adjusted to mimic deficient (0.23 muM), serum-level (3.6 muM), and zinc-rich (50 muM) conditions. It was found that cells exhibited distinct anisotropic migration in serum-level zinc and zinc-deficient media on the wide PDMS patterns, however this was disrupted under zinc-rich conditions. Production of differentiation effectors, activated metalloproteinase-2 (MMP-2) and transforming growth factor - beta 1 (TGF-beta1), was increased with the addition of exogenous zinc. Early stage differentiation, via alkaline phosphatase, was modified by zinc levels on patterned polydimethylsiloxane (PDMS) surfaces, but not on flat PDMS or tissue culture polystyrene (TC). Late stage differentiation, visualized through calcium phosphate nodules, was markedly different at various zinc levels when the cells were cultured on TC substrates. This susceptibility to zinc content can lead to differences in bone mineral production on certain substrates if osteoblasts are not able to maintain and remodel bone effectively, a process vital to successful biomaterial integration.

  11. Mechanical Properties and Corrosion Behavior of CeO2 and SiC Incorporated Al5083 Alloy Surface Composites

    Science.gov (United States)

    Amra, M.; Ranjbar, Khalil; Dehmolaei, R.

    2015-08-01

    In this investigation, nano-sized cerium oxide (CeO2) and silicon carbide (SiC) particles were stirred and mixed into the surface of an Al5083 alloy rolled plate using friction stir processing (FSP) to form a surface nano-composite layer. For this purpose, various volume ratios of the reinforcements either separately or in the combined form were packed into a pre-machined groove on the surface of the plate. Microstructural features, mechanical properties, and corrosion behavior of the resultant surface composites were determined. Microstructural analysis, optical microscopy and scanning electron microscopy, showed that reinforcement particles were fairly dispersed inside the stir zone and grain refinement was gained. Compared with the base alloy, all of the FSP composites showed higher hardness and tensile strength values with the maximum being obtained for the composite containing 100% SiC particles, i.e., Al5083/SiC. The corrosion behavior of the samples was studied by conducting potentiodynamic polarization tests and assessed in terms of corrosion potential, pitting potential, and passivation range. The result shows a significant increase in corrosion resistance of the base alloy; i.e., the longest passivation range when CeO2 alone was incorporated into the surface by acting as cathodic inhibitors. Composites reinforced with SiC particles exhibited lower pitting resistance due to the formation of microgalvanic couples between cathodic SiC particles and anodic aluminum matrix. The study was aimed to fabricate metal matrix surface composites with improved hardness, tensile strength, and corrosion resistance by the incorporation of CeO2 and SiC reinforcement particles into the surface of Al5083 base alloy. Optimum mechanical properties and corrosion resistance were obtained for the FSP composite Al5083/(75%CeO2 + 25%SiC). In this particular FSP composite, hardness and tensile strength were increased by 30, and 14%, respectively, and passivation range was increased

  12. Controllable fabrication of zinc borate hierarchical nanostructure on brucite surface for enhanced mechanical properties and flame retardant behaviors.

    Science.gov (United States)

    Wang, Xuesong; Pang, Hongchang; Chen, Wendan; Lin, Yuan; Zong, Lishuai; Ning, Guiling

    2014-05-28

    A novel and efficient halogen-free composite flame retardant (CFR) consisting of a brucite core and a fine zinc borate [Zn6O(OH)(BO3)3] hierarchical nanostructure shell was designed and synthesized via a facile nanoengineering route. It had been demonstrated that this unique hybrid structure possessed a high BET specific surface area (65 m(2)/g) and could significantly enhance the interfacial interaction when mixing with ethylene-vinyl acetate (EVA). This improved the transfer of stress between CFR particles and EVA matrix and increased the viscosity of EVA/EVA blends, which was beneficial for droplet inhibition and char forming. The mechanical properties and flammability behaviors of the EVA/CFR blends had been compared with the EVA/physical mixture (PM, with the given proportion of brucite and Zn6O(OH)(BO3)3). The mechanical properties of EVA/CFR blends, especially the tensile strength (TS), presented a remarkable increase reaching at least a 20% increment. Meanwhile, with the same 45 wt % of fillers, the EVA/CFR formulation could achieve a limiting oxygen index (LOI) value of 33 (37.5 % higher than that of EVA/PM blends) and UL-94 V-0 rating. Moreover, the heat release rate (HRR), peak heat release rate (PHRR), total heat released (THR), smoke production rate (SPR) and mass loss rate (MLR) were considerably reduced, especially PHRR and SPR for EVA/CFR blends were reduced to 32%. According to this study, the design of fine structure might pave the way for the future development of halogen-free flame retardants combining both enhanced mechanical properties and excellent flame retardant behaviors. PMID:24813539

  13. Cleaning and surface properties

    CERN Document Server

    Taborelli, M

    2007-01-01

    Principles of precision cleaning for ultra high vacuum applications are reviewed together with the techniques for the evaluation of surface cleanliness. Methods to verify the effectiveness of cleaning procedures are discussed. Examples are presented to illustrate the influence of packaging and storage on the recontamination of the surface after cleaning. Finally, the effect of contamination on some relevant surface properties, like secondary electron emission and wettability is presented.

  14. Average nuclear surface properties

    International Nuclear Information System (INIS)

    The definition of the nuclear surface energy is discussed for semi-infinite matter. This definition is extended also for the case that there is a neutron gas instead of vacuum on the one side of the plane surface. The calculations were performed with the Thomas-Fermi Model of Syler and Blanchard. The parameters of the interaction of this model were determined by a least squares fit to experimental masses. The quality of this fit is discussed with respect to nuclear masses and density distributions. The average surface properties were calculated for different particle asymmetry of the nucleon-matter ranging from symmetry beyond the neutron-drip line until the system no longer can maintain the surface boundary and becomes homogeneous. The results of the calculations are incorporated in the nuclear Droplet Model which then was fitted to experimental masses. (orig.)

  15. Critical behavior of collapsing surfaces

    DEFF Research Database (Denmark)

    Olsen, Kasper; Sourdis, C.

    2009-01-01

    We consider the mean curvature evolution of rotationally symmetric surfaces. Using numerical methods, we detect critical behavior at the threshold of singularity formation resembling that of gravitational collapse. In particular, the mean curvature simulation of a one-parameter family of initial...

  16. Behavior of Aluminum Based Coagulants in Treatment of Surface Water–Assessment of Chemical and Microbiological Properties of Treated Water

    OpenAIRE

    Spînu (Gologan) Daniela; Racoviteanu Gabriel

    2014-01-01

    Pre-polymerized inorganic aluminum coagulants have high efficiency in reducing turbidity, total, dissolved, biodegradable organic carbon and microbiological content of surface waters used for drinking, while obtaining low concentrations of residual aluminum after the coagulation phase. Correlation between turbidity raw water and coagulant dose is logarithmic being influenced by temperature and organic content of surface waters. The coagulant’s effect on the organic content of the raw water is...

  17. Superhydrophobic Behavior on Nano-structured Surfaces

    Science.gov (United States)

    Schaeffer, Daniel

    2008-05-01

    Superhydrophobic behavior is observed in natural occurrences and has been thoroughly studied over the past few years. Water repellant properties on uniform arrays of vertically aligned nano-cones were investigated to determine the highest achievable contact angle (a measure of water drop repellency), which is measured from the reference plane on which the water drop sits to the tangent line of the point at which the drop makes contact with the reference plane. At low aspect ratios (height vs. width of the nano-cones), surface tension pulls the water into the nano-cone array, resulting in a wetted surface. Higher aspect ratios reverse the effect of the surface tension, resulting in a larger contact angle that causes water drops to roll off the surface. Fiber drawing, bundling, and redrawing are used to produce the structured array glass composite surface. Triple-drawn fibers are fused together, annealed, and sliced into thin wafers. The surface of the composite glass is etched to form nano-cones through a differential etching process and then coated with a fluorinated self-assembled monolayer (SAM). Cone aspect ratios can be varied through changes in the chemistry and concentration of the etching acid solution. Superhydrophobic behavior occurs at contact angles >150 and it is predicted and measured that optimal behavior is achieved when the aspect ratio is 4:1, which displays contact angles >=175 .

  18. Effect of Oxygen on Surface Properties and Drug Release Behavior of Plasma Polymer of n-Butyl Methacrylate

    Institute of Scientific and Technical Information of China (English)

    Yuan YUAN; Chang Sheng LIU; Yuan ZHANG; Min YIN; Jie XU

    2005-01-01

    The effects of oxygen on the chemical structure, morphology, hydrophilicity and drug release behavior of radio-frequency plasma poly n- butyl methacrylate (PPBMA) thin film were carried out for the first time. ATR-FTIR and XPS showed that oxygen had little influence on the chemical structure and composition of PPBMAs, which did not agree with the thought that the presence of oxygen gas would increase the oxidized carbon functionalities in the plasma polymer.SEM and static contact angle measurement indicated that in case of deposition with oxygen, the smoothness and hydrophilicity of PPBMA were dramatically improved. The drug release behavior showed that drug release from the PPBMA coating without oxygen was biphasic patterns,while from PPBMA coating with oxygen was Higuchi release. These results were helpful for the design and tailoring of the PPBMA polymer film and other of plasma polymers film, but could provide a new idea for the drug release controlled form.

  19. Behavior of Aluminum Based Coagulants in Treatment of Surface Water–Assessment of Chemical and Microbiological Properties of Treated Water

    Directory of Open Access Journals (Sweden)

    Spînu (Gologan Daniela

    2014-03-01

    Full Text Available Pre-polymerized inorganic aluminum coagulants have high efficiency in reducing turbidity, total, dissolved, biodegradable organic carbon and microbiological content of surface waters used for drinking, while obtaining low concentrations of residual aluminum after the coagulation phase. Correlation between turbidity raw water and coagulant dose is logarithmic being influenced by temperature and organic content of surface waters. The coagulant’s effect on the organic content of the raw water is closely related to the microbiological concentration and can thus determine the mathematical correlations between the two types of parameters after the coagulation-flocculation stage that can be used to assess the water biostability coagulant action.

  20. Surface properties of indium pnictides

    International Nuclear Information System (INIS)

    The analysis of the complex study on the composition, nature of active centers adsorption properties of the InB5 semiconductor surface properties is carried out. The above studies made it possible to reveal the identity and regularities in changing the surface properties of the semiconductors under study; they prove, that coordination - unsaturated surface atoms and vacancies of the Β-elements are mainly responsible for gas adsorption and that their adsorption activity may be changed through change of their state and concentration

  1. Fundamental behavior of montmorillonite surfaces

    International Nuclear Information System (INIS)

    linearly during the whole 24 hour period, except during the first few minutes when the increase is sharper. There is no clear correlation with the different pH regions, but apparently the ionic strength of the solution increases at a constant rate as a function of time (after the first few minutes), which most likely is a consequence of montmorillonite dissolution. Elemental analysis data support this conclusion although it cannot be completely ruled out that some colloids still remain in the solution after the separation process. The initial fast process is clearly associated with hydrolysis reactions and rapid dissolution of weak structural spots (possibly including dissolution of trace amounts of accessory minerals). Hence the fast increase in conductivity. Monitoring of compacted bentonite suspended in water (as opposed to a colloidal suspension) demonstrates even more visibly that hydrolysis processes play an important role in the initial interactions between montmorillonite and water. The rapid drop in pH from ∼9 to 6.5 shows that hydrolysis occurs at a larger scale in the solution containing compacted montmorillonite than in the solution containing montmorillonite colloids since the consumption of OH- is clearly larger. This is undoubtedly due to a much larger available surface area. However, very complex behavior is observed during the initial 1.5 h, which could originate partly from ion migration in and out of the montmorillonite matrix and partly from surface reactions

  2. Optical behavior of surface bubbles

    Science.gov (United States)

    Straulino, Samuele; Gambi, Cecilia M. C.; Molesini, Giuseppe

    2015-11-01

    The observation of diamond-like light spots produced by surface bubbles obliquely illuminated is reported. The phenomenon is discussed in terms of geometrical optics, and an explanation is provided attributing the effect to the astigmatism introduced by the deformation of the liquid surface surrounding the bubble. An essential ray tracing program is outlined and used to reconstruct the observed phenomenon numerically.

  3. Nanomechanical properties of rough surfaces

    Directory of Open Access Journals (Sweden)

    Gelson Biscaia de Souza

    2006-06-01

    Full Text Available The nanoindentation technique allows the determination of mechanical properties at nanometric scale. Hardness (H and elastic modulus (E profiles are usually determined by using the Oliver-Pharr method from the load/unload curves. This approach is valid only for flat surfaces, or at least, when a very low degree of asperity is present (lower than 30 nm. The basic statement is the determination of the zero tip-surface contact point. If a rough surface is present, errors can occur in determining this contact point and, as a consequence, the surface hardness and elastic modulus profiles are drastically altered resulting in under evaluated values. Surfaces with different roughness were produced by controlled nitrogen glow discharge process on titanium. The changed nitriding parameters were different N2/H2 atmospheres and temperatures (600 °C-900 °C. The most correct H and E profiles were obtained by using the contact stiffness analysis method, proposed here, that overcomes the surface roughness. The obtained results were compared with available literature data.

  4. Surface sensing behavior and band edge properties of AgAlS2: Experimental observations in optical, chemical, and thermoreflectance spectroscopy

    Directory of Open Access Journals (Sweden)

    Ching-Hwa Ho

    2012-06-01

    Full Text Available Optical examination of a chaocogenide compound AgAlS2 which can spontaneously transfer to a AgAlO2 oxide has been investigated by thermoreflectance (TR spectroscopy herein. The single crystals of AgAlS2 were grown by chemical vapor transport (CVT method using ICl3 as a transport agent sealed in evacuated quartz tubes. The as-grown AgAlS2 crystals essentially possess a transparent and white color in vacuum. The crystal surface of AgAlS2 becomes darkened and brownish when putting AgAlS2 into atmosphere for reacting with water vapor or hydrogen gas. Undergoing the chemical reaction process, oxygen deficient AgAlO2-2x with brownish and reddish-like color on surface of AgAlS2 forms. The transition energy of deficient AgAlO2-2x was evaluated by TR experiment. The value was determined to be ∼2.452 eV at 300 K. If the sample is kept dry and moved away from moisture, AgAlS2 crystal can stop forming more deficient AgAlO2-2x surface oxides. The experimental TR spectra for the surface-reacted sample show clearly two transition features at EW=2.452 eV for deficient AgAlO2-2x and EU=3.186 eV for AgAlS2, respectively. The EU transition belongs to direct band-edge exciton of AgAlS2. Alternatively, for surface-oxidation process of AgAlS2 lasting for a long time, a AgAlO2 crystal with yellowish color will eventually form. The TR measurements show mainly a ground-state band edge exciton of E OX 1 detected for AgAlO2. The energy was determined to be E OX 1=2.792 eV at 300 K. The valence-band electronic structure of AgAlS2 has been detailed characterized using polarized-thermoreflectance (PTR measurements in the temperature range between 30 and 340 K. Physical chemistry behaviors of AgAlS2 and AgAlO2 have been comprehensively studied via detailed analyses of PTR and TR spectra. Based on the experimental analyses, optical and chemical behaviors of the AgAlS2 crystals under atmosphere are realized. A possible optical-detecting scheme for using AgAlS2 as a humidity

  5. Coagulation behavior and floc properties of compound bioflocculant-polyaluminum chloride dual-coagulants and polymeric aluminum in low temperature surface water treatment.

    Science.gov (United States)

    Huang, Xin; Sun, Shenglei; Gao, Baoyu; Yue, Qinyan; Wang, Yan; Li, Qian

    2015-04-01

    This study was intended to compare coagulation behavior and floc properties of two dual-coagulants polyaluminum chloride-compound bioflocculant (PAC-CBF) (PAC dose first) and compound bioflocculant-polyaluminum chloride (CBF-PAC) (CBF dose first) with those of PAC alone in low temperature drinking water treatment. Results showed that dual-coagulants could improve DOC removal efficiency from 30% up to 34%. Moreover, CBF contributed to the increase of floc size and growth rate, especially those of PAC-CBF were almost twice bigger than those of PAC. However, dual-coagulants formed looser and weaker flocs with lower breakage factors in which fractal dimension of PAC-CBF flocs was low which indicates a looser floc structure. The floc recovery ability was in the following order: PAC-CBF>PAC alone>CBF-PAC. The flocculation mechanism of PAC was charge neutralization and enmeshment, meanwhile the negatively charged CBF added absorption and bridging effect. PMID:25872730

  6. Immobilized Multifunctional Polymersomes on Solid Surfaces: Infrared Light-Induced Selective Photochemical Reactions, pH Responsive Behavior, and Probing Mechanical Properties under Liquid Phase.

    Science.gov (United States)

    Iyisan, Banu; Janke, Andreas; Reichenbach, Philipp; Eng, Lukas M; Appelhans, Dietmar; Voit, Brigitte

    2016-06-22

    Fixing polymersomes onto surfaces is in high demand not only for the characterization with advanced microscopy techniques but also for designing specific compartments in microsystem devices in the scope of nanobiotechnology. For this purpose, this study reports the immobilization of multifunctional, responsive, and photo-cross-linked polymersomes on solid substrates by utilizing strong adamantane-β-cyclodextrin host-guest interactions. To reduce nonspecific binding and retain better spherical shape, the level of attractive forces acting on the immobilized polymersomes was tuned through poly(ethylene glycol) passivation as well as decreased β-cyclodextrin content on the corresponding substrates. One significant feature of this system is the pH responsivity of the polymersomes which has been demonstrated by swelling of the immobilized vesicles at acidic condition through in situ AFM measurements. Also, light responsivity has been provided by introducing nitroveratryloxycarbonyl (NVOC) protected amine molecules as photocleavable groups to the polymersome surface before immobilization. The subsequent low-energy femtosecond pulsed laser irradiation resulted in the cleavage of NVOC groups on immobilized polymersomes which in turn led to free amino groups as an additional functionality. The freed amines were further conjugated with a fluorescent dye having an activated ester that illustrates the concept of bio/chemo recognition for a potential binding of biological compounds. In addition to the responsive nature, the mechanical stability of the analyzed polymersomes was supported by computing Young's modulus and bending modulus of the membrane through force curves obtained by atomic force microscopy measurements. Overall, polymersomes with a robust and pH-swellable membrane combined with effective light responsive behavior are promising tools to design smart and stable compartments on surfaces for the development of microsystem devices such as chemo/biosensors. PMID

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

    Energy Technology Data Exchange (ETDEWEB)

    Choo, Soyoung; Choi, Hak-Jong; Lee, Heon, E-mail: heonlee@korea.ac.kr

    2015-01-01

    Highlights: • Superhydrophobic surfaces with superhydrophilic micropatterns were fabricated. • Dual-nanorod structures of TiO{sub 2} and ZnO were achieved using the hydrothermal method. • The condensation property and adhesive force of the patterned surfaces were confirmed. • Water collecting efficiency on the surface as a function of the degree was confirmed. • The water-collecting behavior of the various pattern designs was confirmed. - Abstract: Dew is commonly formed even in dry regions, and we examined the suitability of surfaces with superhydrophilic patterns on a superhydrophobic background as a dew-harvesting system. Nanostructured surfaces with mixed wettability were fabricated by ZnO and TiO{sub 2} nanorods. The condensation properties were investigated by environmental scanning electron microscopy (ESEM), and the water-collecting function of the patterned surfaces in an artificial environment was confirmed. Condensation and water-collecting behavior were evaluated as a function of surface inclination angle and pattern shape. We examined the collecting efficiency among the different wettabilities at various inclination angles and observed the condensation behavior for various superhydrophilic shapes.

  8. Cells behaviors and genotoxicity on topological surface

    Energy Technology Data Exchange (ETDEWEB)

    Yang, N.; Yang, M.K.; Bi, S.X. [Tianjin Key Laboratory of Fiber Modification and Functional Fiber, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin, 300387 (China); Chen, L., E-mail: chenlis@tjpu.edu.cn [Tianjin Key Laboratory of Fiber Modification and Functional Fiber, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin, 300387 (China); Zhu, Z.Y.; Gao, Y.T.; Du, Z. [Tianjin Key Laboratory of Artificial Cell, Tianjin Third Central Hospital, Tianjin, 300170 (China)

    2013-08-01

    To investigate different cells behaviors and genotoxicity, which were driven by specific microenvironments, three patterned surfaces (pillars, wide grooves and narrow grooves) and one smooth surface were prepared by template-based technique. Vinculin is a membrane-cytoskeletal protein in focal adhesion plaques and associates with cell–cell and cell–matrix junctions, which can promote cell adhesion and spreading. The immunofluorescence staining of vinculin revealed that the narrow grooves patterned substrate was favorable for L929 cell adhesion. For cell multiplication, the narrow grooves surface was fitted for the proliferation of L929, L02 and MSC cells, the pillars surface was only in favor of L929 cells to proliferate during 7 days of cell cultivation. Cell genetic toxicity was evaluated by cellular micronuclei test (MNT). The results indicated that topological surfaces were more suitable for L929 cells to proliferate and maintain the stability of genome. On the contrary, the narrow grooves surface induced higher micronuclei ratio of L02 and MSC cells than other surfaces. With the comprehensive results of cell multiplication and MNT, it was concluded that the wide grooves surface was best fitted for L02 cells to proliferate and have less DNA damages, and the smooth surface was optimum for the research of MSC cells in vitro. - Highlights: • Different cells behaviors on microstructure surfaces were discussed in this paper. • The expression of cell protein of Vinculin was studied in this research. • Cellular micronuclei test was applied to evaluate cells' genotoxicity. • Cell genotoxicity was first studied in the research field of topological surfaces.

  9. Cells behaviors and genotoxicity on topological surface

    International Nuclear Information System (INIS)

    To investigate different cells behaviors and genotoxicity, which were driven by specific microenvironments, three patterned surfaces (pillars, wide grooves and narrow grooves) and one smooth surface were prepared by template-based technique. Vinculin is a membrane-cytoskeletal protein in focal adhesion plaques and associates with cell–cell and cell–matrix junctions, which can promote cell adhesion and spreading. The immunofluorescence staining of vinculin revealed that the narrow grooves patterned substrate was favorable for L929 cell adhesion. For cell multiplication, the narrow grooves surface was fitted for the proliferation of L929, L02 and MSC cells, the pillars surface was only in favor of L929 cells to proliferate during 7 days of cell cultivation. Cell genetic toxicity was evaluated by cellular micronuclei test (MNT). The results indicated that topological surfaces were more suitable for L929 cells to proliferate and maintain the stability of genome. On the contrary, the narrow grooves surface induced higher micronuclei ratio of L02 and MSC cells than other surfaces. With the comprehensive results of cell multiplication and MNT, it was concluded that the wide grooves surface was best fitted for L02 cells to proliferate and have less DNA damages, and the smooth surface was optimum for the research of MSC cells in vitro. - Highlights: • Different cells behaviors on microstructure surfaces were discussed in this paper. • The expression of cell protein of Vinculin was studied in this research. • Cellular micronuclei test was applied to evaluate cells' genotoxicity. • Cell genotoxicity was first studied in the research field of topological surfaces

  10. Lunar Surface Properties from Diviner Eclipse Observations

    Science.gov (United States)

    Hayne, Paul; Paige, David; Greenhagen, Benjamin; Bandfield, Joshua; Siegler, Matthew; Lucey, Paul

    2015-04-01

    The thermal behavior of planetary bodies can reveal information about fundamental processes shaping their surfaces and interiors. Diviner [1] has been mapping the Moon's diurnal temperatures since the Lunar Reconnaissance Orbiter (LRO) arrived in 2009, yielding new insights into regolith formation [2, 3], the distribution of volatiles [4, 5], lunar volcanism [6, 7, 8], and impact processes [9]. The Moon's cooling during eclipse provides complementary information on the physical properties of the uppermost surface layer, which can be used to further investigate these and other processes. We used data from Diviner's seven thermal infrared spectral channels to measure surface temperatures before, during and after the 8 Oct., 2014 eclipse. In its standard nadir-pushbroom mode, Diviner maps surface temperatures in a ~6-km swath with a spatial resolution of ~250 m. Using Diviner's independent scanning capability [11], we also targeted two regions of interest on sequential orbits to create a time series of thermal observations: 1) Kepler crater (-38°E, 8°N) and 2) an unnamed nighttime "cold spot" (-33.3°E, 3°N). Pre-eclipse surface temperatures in these regions were ~380 K. As a relatively young Copernican-aged impact crater, Kepler was selected to investigate the abundance and size distribution of rocks in the ejecta and interior. Lunar nighttime "cold spots" are anomalous features around very young impact craters, extending for up to hundreds of crater radii, notable for their low temperatures in the Diviner nighttime data [9]. Although their origins are not fully explained, they are likely the result of in-situ disruption and decompression of regolith during the impact process. The selected cold spot (one of hundreds or even thousands on the lunar surface) was located with good viewing ge- ometry from LRO, and had a diameter of ~10 km surrounding a crater Technology, under contract with the National Aeronautics and Space Administration.

  11. Physicochemical properties of a cadmium telluride surface

    International Nuclear Information System (INIS)

    Change of chemical state of cadmium telluride surface is investigated after different treatments (exposure in air, vacuum, gaseous media, γ- and IR-irradiation). The results of these investigations are of great interest for clarifying the nature of active surface of diamond-like semiconductors, the mechanism of its interaction with different media and the possibilities of surface properties regulation

  12. The unusual properties of beryllium surfaces

    International Nuclear Information System (INIS)

    Be is a ''marginal metal.'' The stable phase, hcp-Be, has a low Fermi-level density of states and very anisotropic structural and elastic properties, similar to a semiconductor's. At the Be(0001) surface, surface states drastically increase the Fermi-level density of states. The different nature of bonding in bulk-Be and at the Be(0001) surface explains the large outward relaxation. The presence of surface states causes large surface core-level shifts by inducing a higher electrostatic potential in the surface layers and by improving the screening at the surface. The authors experimental and theoretical investigations of atomic vibrations at the Be(0001) surface demonstrate clearly that Be screening of atomic motion by the surface states makes the surface phonon dispersion fundamentally different from that of the bulk. Properties of Be(0001) are so different from those of the bulk that the surface can be considered a new ''phase'' of beryllium with unique electronic and structural characteristics. For comparison they also study Be(11 bar 20), a very open surface without important surface states. Be(11 bar 20) is the only clean s-p metal surface known to reconstruct (1 x 3 missing row reconstruction)

  13. Wetting properties of molecularly rough surfaces

    International Nuclear Information System (INIS)

    We employ molecular dynamics simulations to study the wettability of nanoscale rough surfaces in systems governed by Lennard-Jones (LJ) interactions. We consider both smooth and molecularly rough planar surfaces. Solid substrates are modeled as a static collection of LJ particles arranged in a face-centered cubic lattice with the (100) surface exposed to the LJ fluid. Molecularly rough solid surfaces are prepared by removing several strips of LJ atoms from the external layers of the substrate, i.e., forming parallel nanogrooves on the surface. We vary the solid-fluid interactions to investigate strongly and weakly wettable surfaces. We determine the wetting properties by measuring the equilibrium droplet profiles that are in turn used to evaluate the contact angles. Macroscopic arguments, such as those leading to Wenzel’s law, suggest that surface roughness always amplifies the wetting properties of a lyophilic surface. However, our results indicate the opposite effect from roughness for microscopically corrugated surfaces, i.e., surface roughness deteriorates the substrate wettability. Adding the roughness to a strongly wettable surface shrinks the surface area wet with the liquid, and it either increases or only marginally affects the contact angle, depending on the degree of liquid adsorption into the nanogrooves. For a weakly wettable surface, the roughness changes the surface character from lyophilic to lyophobic due to a weakening of the solid-fluid interactions by the presence of the nanogrooves and the weaker adsorption of the liquid into the nanogrooves

  14. Metrology and properties of engineering surfaces

    CERN Document Server

    Greenwood, J; Chetwynd, D

    2001-01-01

    Metrology and Properties of Engineering Surfaces provides in a single volume a comprehensive and authoritative treatment of the crucial topics involved in the metrology and properties of engineering surfaces. The subject matter is a central issue in manufacturing technology, since the quality and reliability of manufactured components depend greatly upon the selection and qualities of the appropriate materials as ascertained through measurement. The book can in broad terms be split into two parts; the first deals with the metrology of engineering surfaces and covers the important issues relating to the measurement and characterization of surfaces in both two and three dimensions. This covers topics such as filtering, power spectral densities, autocorrelation functions and the use of Fractals in topography. A significant proportion is dedicated to the calibration of scanning probe microscopes using the latest techniques. The remainder of the book deals with the properties of engineering surfaces and covers a w...

  15. Wettability influences cell behavior on superhydrophobic surfaces with different topographies

    OpenAIRE

    Lourenco, B.N.; Marchioli, G.; Song, W.; Reis, R.L.; Blitterswijk, van, C.A.; Karperien, H.B.J.; Apeldoorn, van, D.F.; Mano, J.F

    2012-01-01

    Surface wettability and topography are recognized as critical factors influencing cell behavior on biomaterials. So far only few works have reported cell responses on surfaces exhibiting extreme wettability in combination with surface topography. The goal of this work is to study whether cell behavior on superhydrophobic surfaces is influenced by surface topography and polymer type. Biomimetic superhydrophobic rough surfaces of polystyrene and poly(l-lactic acid) with different micro/nanotopo...

  16. Structure and properties of water film adsorbed on mica surfaces

    Science.gov (United States)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  17. Enhancement of surface properties for coal beneficiation

    Energy Technology Data Exchange (ETDEWEB)

    Chander, S.; Aplan, F.F.

    1992-01-30

    This report will focus on means of pyrite removal from coal using surface-based coal cleaning technologies. The major subjects being addressed in this study are the natural and modulated surface properties of coal and pyrite and how they may best be utilized to facilitate their separation using advanced surface-based coal cleaning technology. Emphasis is based on modified flotation and oil agglomerative processes and the basic principles involved. The four areas being addressed are: (1) Collectorless flotation of pyrite; (2) Modulation of pyrite and coal hydrophobicity; (3) Emulsion processes and principles; (4) Evaluation of coal hydrophobicity.

  18. Mechanical and tribological properties of ion beam-processed surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kodali, P.

    1998-01-01

    The intent of this work was to broaden the applications of well-established surface modification techniques and to elucidate the various wear mechanisms that occur in sliding contact of ion-beam processed surfaces. The investigation included characterization and evaluation of coatings and modified surfaces synthesized by three surface engineering methods; namely, beam-line ion implantation, plasma-source ion implantation, and DC magnetron sputtering. Correlation among measured properties such as surface hardness, fracture toughness, and wear behavior was also examined. This dissertation focused on the following areas of research: (1) investigating the mechanical and tribological properties of mixed implantation of carbon and nitrogen into single crystal silicon by beam-line implantation; (2) characterizing the mechanical and tribological properties of diamond-like carbon (DLC) coatings processed by plasma source ion implantation; and (3) developing and evaluating metastable boron-carbon-nitrogen (BCN) compound coatings for mechanical and tribological properties. The surface hardness of a mixed carbon-nitrogen implant sample improved significantly compared to the unimplanted sample. However, the enhancement in the wear factor of this sample was found to be less significant than carbon-implanted samples. The presence of nitrogen might be responsible for the degraded wear behavior since nitrogen-implantation alone resulted in no improvement in the wear factor. DLC coatings have low friction, low wear factor, and high hardness. The fracture toughness of DLC coatings has been estimated for the first time. The wear mechanism in DLC coatings investigated with a ruby slider under a contact stress of 1 GPa was determined to be plastic deformation. The preliminary data on metastable BCN compound coatings indicated high friction, low wear factor, and high hardness.

  19. Mechanical and tribological properties of ion beam-processed surfaces

    International Nuclear Information System (INIS)

    The intent of this work was to broaden the applications of well-established surface modification techniques and to elucidate the various wear mechanisms that occur in sliding contact of ion-beam processed surfaces. The investigation included characterization and evaluation of coatings and modified surfaces synthesized by three surface engineering methods; namely, beam-line ion implantation, plasma-source ion implantation, and DC magnetron sputtering. Correlation among measured properties such as surface hardness, fracture toughness, and wear behavior was also examined. This dissertation focused on the following areas of research: (1) investigating the mechanical and tribological properties of mixed implantation of carbon and nitrogen into single crystal silicon by beam-line implantation; (2) characterizing the mechanical and tribological properties of diamond-like carbon (DLC) coatings processed by plasma source ion implantation; and (3) developing and evaluating metastable boron-carbon-nitrogen (BCN) compound coatings for mechanical and tribological properties. The surface hardness of a mixed carbon-nitrogen implant sample improved significantly compared to the unimplanted sample. However, the enhancement in the wear factor of this sample was found to be less significant than carbon-implanted samples. The presence of nitrogen might be responsible for the degraded wear behavior since nitrogen-implantation alone resulted in no improvement in the wear factor. DLC coatings have low friction, low wear factor, and high hardness. The fracture toughness of DLC coatings has been estimated for the first time. The wear mechanism in DLC coatings investigated with a ruby slider under a contact stress of 1 GPa was determined to be plastic deformation. The preliminary data on metastable BCN compound coatings indicated high friction, low wear factor, and high hardness

  20. Surface and mechanical properties of polypropylene/clay nanocomposite

    Directory of Open Access Journals (Sweden)

    Dibaei Asl Husein

    2013-01-01

    Full Text Available Huge consumption of polypropylene in the industries like automotive motivates academic and industrial R&Ds to find new and excellent approaches to improve the mechanical properties of this polymer, which has no degradation effect on other required performance properties like impact resistance, controlled crystallinity, toughness and shrinkage. Nowadays, nanoparticles play a key role in improving the mechanical and surface properties of polypropylene. In this study, three compositions of "Polypropylene/nanoclay", containing 0%, 2% and 5% of nanoclay were prepared in internal mixer. For characterizing the nanoclay dispersion in polymer bulk, TEM and XRD tests were used. For scratch resistance test, scratch lines were created on the load of 900 grain on sheets and SEM images were taken and compared with neat PP scratch image. Crystallinity and mechanical behavior were studied. The results showed that mechanical properties and scratch resistance of the composites have been improved.

  1. Welcome to Surface Topography: Metrology and Properties

    Science.gov (United States)

    Leach, Richard

    2013-11-01

    I am delighted to welcome readers to this inaugural issue of Surface Topography: Metrology and Properties (STMP). In these days of citation indexes and academic reviews, it is a tough, and maybe a brave, job to start a new journal. But the subject area has never been more active and we are seeing genuine breakthroughs in the use of surfaces to control functional performance. Most manufactured parts rely on some form of control of their surface characteristics. The surface is usually defined as that feature on a component or device, which interacts with either the environment in which it is housed (or in which the device operates), or with another surface. The surface topography and material characteristics of a part can affect how fluids interact with it, how the part looks and feels and how two bearing parts will slide together. The need to control, and hence measure, surface features is becoming increasingly important as we move into a miniaturized world. Surface features can become the dominant functional features of a part and may become large in comparison to the overall size of an object. Research into surface texture measurement and characterization has been carried out for over a century and is now more active than ever, especially as new areal surface texture specification standards begin to be introduced. The range of disciplines for which the function of a surface relates to its topography is very diverse; from metal sheet manufacturing to art restoration, from plastic electronics to forensics. Until now, there has been no obvious publishing venue to bring together all these applications with the underlying research and theory, or to unite those working in academia with engineering and industry. Hence the creation of Surface Topography: Metrology and Properties . STMP will publish the best work being done across this broad discipline in one journal, helping researchers to share common themes and highlighting and promoting the extraordinary benefits this

  2. Corrosion behavior of superhydrophobic surfaces: A review

    OpenAIRE

    Mohamed, Adel M.A.; Abdullah, Aboubakr M.; Younan, Nathalie A.

    2015-01-01

    Superhydrophobic surfaces have evoked great interest in researchers for both purely academic pursuits and industrial applications. Metal corrosion is a serious problem, both economically and operationally, for engineering systems such as aircraft, automobiles, pipelines, and naval vessels. Due to the broad range of potential applications of superhydrophobic surfaces, there is a need for a deeper understanding of not only how to fabricate such surfaces using simple methods, but also how specif...

  3. Phase behavior of Au and Pt surfaces

    DEFF Research Database (Denmark)

    Grübel, G.; Gibbs, D.; Zehner, D.M.;

    1993-01-01

    We summarize the results of X-ray scattering studies of the Au(001) and Pt(001) surfaces between 300 K and their respective bulk melting temperatures (T(m)). Both surfaces exhibit three distinct structural phases. At high temperatures (0.88T(m) < T < T(m)) both surfaces are disordered. The Pt(001......) surface is rough. At a temperature of T/T(m) almost-equal-to 0.88 there are reversible phase transformations to incommensurate, corrugated-hexagonal phases. Below T/T(m) almost-equal-to 0.8 hexagonal domains rotate with respect to the substrate orientation. In Pt, the rotational transformation is...

  4. Surface properties of polyethylene grafted by plasma

    Czech Academy of Sciences Publication Activity Database

    Novák, I.; Nedelčev, T.; Krupa, I.; Števiar, M.; Chodák, I.; Mosnáček, J.; Špírková, Milena; Chehimi, M. M.

    Praha: Česká společnost průmyslové chemie, 2008, s. 2130-2134. [Konference Aprochem 2008 a Odpadové fórum. Milovy (CZ), 14.04.2008-16.04.2008] Grant ostatní: VEGA(SK) 2/7103/27 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyethylene * surface properties Subject RIV: CD - Macromolecular Chemistry

  5. Effect of surface moisture on dielectric behavior of ultrafine BaTiO3 particulates.

    Science.gov (United States)

    Mountvala, A. J.

    1971-01-01

    The effects of adsorbed H2O on the dielectric properties of ultrafine BaTiO3 particulates of varying particle size and environmental history were determined. The dielectric behavior depends strongly on surface hydration. No particle size dependence of dielectric constant was found for dehydroxylated surfaces in ultrafine particulate (unsintered) BaTiO3 materials. For equivalent particle sizes, the ac conductivity is sensitive to surface morphology. Reactions with H2O vapor appear to account for the variations in dielectric properties. Surface dehydration was effectively accomplished by washing as-received powders in isopropanol.

  6. Molecular processes affecting the macroscopic tribological behavior of surfaces

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the influence of various additives on the tribological properties of a system in the macro and nanoscale, as well as clarify lubricant interactions with surfaces and materials. To accomplish that a wide range of lubricants and additives were considered. Moreover, a detail chemical analysis was carried out, in order to explain the effect on the friction coefficient, wear mechanisms and corrosion process in lubricated tribosystems. This research was mainly focused on additives for water based lubricants. Solutions of anti-corrosion and anti-foaming agents - amines, friction modifiers - glycols and amines derivatives with longer hydrocarbon chains were investigated. The results showed that the additives build chemisorbed mono-molecular films on surfaces, what was verified by AFM, AR-XPS and AES analysis, and compared with SESSA simulation. Investigated tribo-films affect the friction coefficient in nanoscale, however during tribological test in the macroscale, they showed different results depending on contact situation (rolling and/or sliding). The conclusion states that the differences in tribological behavior might be due to the orientation of amine and hydroxyl groups on the surfaces. Furthermore, lubricants for rolling bearing elements such as polar and non polar oils with zinc dialkyldithiophosphate (ZDDP) additives were studied. The results demonstrated that a reaction layer formation is strongly dependent on the molecular polarity of the oils and additives. The evolution of the topography and mechanical properties of the ZDDP-derived tribo-layer with rubbing time showed that initially a thin and soft ZDDP reaction layer develops very quick. The second part of this work was addressed on chemical vapor deposited (CVD) diamond films and transition metal dichalcogenides (TMD) in consideration of desired properties for micro electro mechanical systems (MEMS). The main scientific goal of this part of the work was to

  7. Wettability influences cell behavior on superhydrophobic surfaces with different topographies

    NARCIS (Netherlands)

    Lourenco, B.N.; Marchioli, G.; Song, W; Reis, R.L.; Blitterswijk, van C.A.; Karperien, H.B.J.; Apeldoorn, van A.A.; Mano, J.F.

    2012-01-01

    Surface wettability and topography are recognized as critical factors influencing cell behavior on biomaterials. So far only few works have reported cell responses on surfaces exhibiting extreme wettability in combination with surface topography. The goal of this work is to study whether cell behavi

  8. Structure, electronic properties, and aggregation behavior of hydroxylated carbon nanotubes

    International Nuclear Information System (INIS)

    We present a combined experimental and theoretical study to analyze the structure, electronic properties, and aggregation behavior of hydroxylated multiwalled carbon nanotubes (OH–MWCNT). Our MWCNTs have average diameters of ∼2 nm, lengths of approximately 100–300 nm, and a hydroxyl surface coverage θ∼0.1. When deposited on the air/water interface the OH–MWCNTs are partially soluble and the floating units interact and link with each other forming extended foam-like carbon networks. Surface pressure-area isotherms of the nanotube films are performed using the Langmuir balance method at different equilibration times. The films are transferred into a mica substrate and atomic force microscopy images show that the foam like structure is preserved and reveals fine details of their microstructure. Density functional theory calculations performed on model hydroxylated carbon nanotubes show that low energy atomic configurations are found when the OH groups form molecular islands on the nanotube's surface. This patchy behavior for the OH species is expected to produce nanotubes having reduced wettabilities, in line with experimental observations. OH doping yields nanotubes having small HOMO–LUMO energy gaps and generates a nanotube → OH direction for the charge transfer leading to the existence of more hole carriers in the structures. Our synthesized OH–MWCNTs might have promising applications

  9. Superhydrophilic and Wetting Behavior of TiO2 Films and their Surface Morphologies

    International Nuclear Information System (INIS)

    TiO2 films, showing superhydrophilic behavior, are prepared by electron beam evaporation. Atomic force microscopy and the contact angle measurement were performed to characterize the morphology and wetting behavior of the TiO2 films. Most studies attribute the wetting behavior of TiO2 surfaces to their physical characteristics rather than surface chemistry. These physical characteristics include surface morphology, roughness, and agglomerate size. We arrange these parameters in order of effectiveness. Surface morphologies are demonstrated to be the most important. TiO2 films with particular morphologies show superhydrophilic behavior without external stimuli, and these thin films also show stable anti-contamination properties during cyclical wetting and drying. (cross-disciplinary physics and related areas of science and technology)

  10. Parametric surface and properties defined on parallelogrammic domain

    Directory of Open Access Journals (Sweden)

    Shuqian Fan

    2014-01-01

    Full Text Available Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufactura-bility (and its limitation in logarithmic spiral bevel gears is analyzed using precision forging and multi-axis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multi-axis freeform milling also need to be solved in a further study.

  11. Hydrodynamic slip length as a surface property

    Science.gov (United States)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-02-01

    Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.

  12. Scanning probe microscopy of oxide surfaces: atomic structure and properties

    International Nuclear Information System (INIS)

    The intersection of two fields, oxide surface science and scanning probe microscopy (SPM), has yielded considerable insight on atomic processes at surfaces. Oxide surfaces, especially those containing transition metals, offer a rich variety of structures and localized physical phenomena that are exploited in a wide range of applications. Nonlinear optics, superconductivity, ferroelectricity and chemical catalytic activity are but a few. Furthermore, the challenges and solutions associated with the chemistry of these surfaces and particularly the solutions to these problems have led to important understanding of tip-surface interactions that can inform SPM studies of all materials. Here, the development of understanding of the model systems TiO2 and SrTiO3 are considered in detail, to demonstrate the role of nonstoichiometry in surface structure evolution and the approach to interpreting structure at the atomic level. Then a combination of scanning tunneling microscopy, noncontact atomic force microscopy and theory are applied to a variety of oxide systems including Al2O3, NiO, ferroelectric BaTiO3, tungstates and molybdates. Recently developed sophisticated probes of local properties include spin-polarized tunneling, Fourier mapping of charge density waves, band gap mapping of superconductors and ultra fast imaging of atomic diffusion. The impact of these studies on our understanding of the behavior of oxides and of tip-surface interactions is summarized

  13. Shape Properties of Irregular Surface Data

    Directory of Open Access Journals (Sweden)

    MARIA HUSSAIN

    2012-11-01

    Full Text Available The presented work of this paper addresses the two shape properties, positivity and monotonicity of irregular surface data. The data is initially triangulated and a side-vertex scheme is adopted to interpolate the data over each triangle. Each boundary and radial curve is a rational function with three parameters facilitating 18 parameters in each triangular patch. The presence of these parameters leads to an automotive scheme for shape preservation and shape control. The data dependent constraints are derived on 6 of these parameters for preservation of positive and monotone properties of data, while, remaining 12 are free for shape modification. This scheme is local, does not constrain step length and derivatives, equally applicable to both data and data with derivatives.

  14. Eu2O3: properties and irradiation behavior

    International Nuclear Information System (INIS)

    Europium sesquioxide is an excellent candidate control material for fast reactors. Its properties and behavior have been under extensive investigation at ORNL since 1972. This report is a compilation of the results of these efforts. Processes for synthesizing powders and fabricating dense pellets from them are described. Physical and chemical properties data measured on these pellets, along with their irradiation behavior, are also summarized

  15. Behavior of block-polyampholytes near a charged surface

    OpenAIRE

    Messina, Rene

    2006-01-01

    The behavior of polyampholytes near a charged planar surface is studied by means of Monte Carlo simulations. The investigated polyampholytes are overall electrically neutral and made up of oppositely charged units (called blocks) that are highly charged and of the the same length. The influence of block length and substrate's surface-charge-density on the adsorption behavior is addressed. A detailed structural study, including local monomer concentration, monomer mean height, transversal chai...

  16. Surface properties of copper based cermet materials

    Energy Technology Data Exchange (ETDEWEB)

    Voinea, M. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)], E-mail: m.voinea@unitbv.ro; Vladuta, C.; Bogatu, C.; Duta, A. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)

    2008-08-25

    The paper presents the characterization of the surface properties of copper based cermets obtained by two different techniques: spray pyrolysis deposition (SPD) and electrodeposition. Copper acetate was used as precursor of Cu/CuO{sub x} cermet. The surface morphology was tailored by adding copolymers of maleic anhydride with controlled hydrophobia. The films morphology of Cu/CuO{sub x} was assessed using contact angle measurements and AFM analysis. The porous structures obtained via SPD lead to higher liquid adsorption rate than the electrodeposited films. A highly polar liquid - water is recommended as testing liquid in contact angle measurements, for estimating the porosity of copper based cermets, while glycerol can be used to distinguish among ionic and metal predominant structures. Thus, contact angle measurements can be used for a primary evaluation of the films morphology and, on the other hand, of the ratio between the cermet components.

  17. Formation, dissolution and properties of surface nanobubbles

    CERN Document Server

    Che, Zhizhao

    2016-01-01

    Surface nanobubbles are stable gaseous phases in liquids that form onto solid substrates. While their existence has been confirmed, there are many open questions related to their formation and dissolution processes along with their structure and properties, which are difficult to investigate experimentally. To address these issues, we carried out molecular dynamics simulations based on atomistic force-fields for systems comprised of water, air (N2 and O2), and a Highly Oriented Pyrolytic Graphite (HOPG) substrate. Our results provide insights into the formation/dissolution mechanisms of nanobubbles and estimates for their density, contact angle and surface tension. We found that the formation of nanobubbles is driven by an initial nucleation process of air molecules and the subsequent coalescence of the formed air clusters. The clusters form favorably on the substrate, which provides an enhanced stability to the clusters. In contrast, nanobubbles formed in the bulk move either randomly to the substrate and sp...

  18. Metabolic behavior of cell surface biotinylated proteins

    International Nuclear Information System (INIS)

    The turnover of proteins on the surface of cultured mammalian cells was measured by a new approach. Reactive free amino or sulfhydryl groups on surface-accessible proteins were derivatized with biotinyl reagents and the proteins solubilized from culture dishes with detergent. Solubilized, biotinylated proteins were then adsorbed onto streptavidin-agarose, released with sodium dodecyl sulfate and mercaptoethanol, and separated on polyacrylamide gels. Biotin-epsilon-aminocaproic acid N-hydroxysuccinimide ester (BNHS) or N-biotinoyl-N'-(maleimidohexanoyl)hydrazine (BM) were the derivatizing agents. Only 10-12 bands were adsorbed onto streptavidin-agarose from undervatized cells or from derivatized cells treated with free avidin at 4 degrees C. Two-dimensional isoelectric focusing-sodium dodecyl sulfate gel electrophoresis resolved greater than 100 BNHS-derivatized proteins and greater than 40 BM-derivatized proteins. There appeared to be little overlap between the two groups of derivatized proteins. Short-term pulse-chase studies showed an accumulation of label into both groups of biotinylated proteins up until 1-2 h of chase and a rapid decrease over the next 1-5 h. Delayed appearance of labeled protein at the cell surface was attributed to transit time from site of synthesis. The unexpected and unexplained rapid disappearance of pulse-labeled proteins from the cell surface was invariant for all two-dimensionally resolved proteins and was sensitive to temperature reduction to 18 degrees C. Long-term pulse-chase experiments beginning 4-8 h after the initiation of chase showed the disappearance of derivatized proteins to be a simple first-order process having a half-life of 115 h in the case of BNHS-derivatized proteins and 30 h in the case of BM-derivatized proteins

  19. Surface, structural and tensile properties of proton beam irradiated zirconium

    Science.gov (United States)

    Rafique, Mohsin; Chae, San; Kim, Yong-Soo

    2016-02-01

    This paper reports the surface, structural and tensile properties of proton beam irradiated pure zirconium (99.8%). The Zr samples were irradiated by 3.5 MeV protons using MC-50 cyclotron accelerator at different doses ranging from 1 × 1013 to 1 × 1016 protons/cm2. Both un-irradiated and irradiated samples were characterized using Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction (XRD) and Universal Testing Machine (UTM). The average surface roughness of the specimens was determined by using Nanotech WSxM 5.0 develop 7.0 software. The FESEM results revealed the formation of bubbles, cracks and black spots on the samples' surface at different doses whereas the XRD results indicated the presence of residual stresses in the irradiated specimens. Williamson-Hall analysis of the diffraction peaks was carried out to investigate changes in crystallite size and lattice strain in the irradiated specimens. The tensile properties such as the yield stress, ultimate tensile stress and percentage elongation exhibited a decreasing trend after irradiation in general, however, an inconsistent behavior was observed in their dependence on proton dose. The changes in tensile properties of Zr were associated with the production of radiation-induced defects including bubbles, cracks, precipitates and simultaneous recovery by the thermal energy generated with the increase of irradiation dose.

  20. Effect of gamma radiation on cadmium telluride surface properties

    International Nuclear Information System (INIS)

    The effect of γ-irradiation on the surface properties of cadmium telluride is studied. The possibility of oriented modification of surface properties for increasing the adsorption activity and obtaining the materials, suited for the sensor transducer production, is shown

  1. Oxidative nanopatterning of titanium generates mesoporous surfaces with antimicrobial properties

    Directory of Open Access Journals (Sweden)

    Variola F

    2014-05-01

    Full Text Available Fabio Variola,1,2 Sylvia Francis Zalzal,3 Annie Leduc,3 Jean Barbeau,3 Antonio Nanci31Faculty of Engineering, Department of Mechanical Engineering, 2Faculty of Science, Department of Physics, University of Ottawa, Ottawa, ON, 3Faculty of Dental Medicine, Université de Montréal, Montreal, QC, CanadaAbstract: Mesoporous surfaces generated by oxidative nanopatterning have the capacity to selectively regulate cell behavior, but their impact on microorganisms has not yet been explored. The main objective of this study was to test the effects of such surfaces on the adherence of two common bacteria and one yeast strain that are responsible for nosocomial infections in clinical settings and biomedical applications. In addition, because surface characteristics are known to affect bacterial adhesion, we further characterized the physicochemical properties of the mesoporous surfaces. Focused ion beam (FIB was used to generate ultrathin sections for elemental analysis by energy-dispersive X-ray spectroscopy (EDS, nanobeam electron diffraction (NBED, and high-angle annular dark field (HAADF scanning transmission electron microscopy (STEM imaging. The adherence of Staphylococcus aureus, Escherichia coli and Candida albicans onto titanium disks with mesoporous and polished surfaces was compared. Disks with the two surfaces side-by-side were also used for direct visual comparison. Qualitative and quantitative results from this study indicate that bacterial adhesion is significantly hindered by the mesoporous surface. In addition, we provide evidence that it alters structural parameters of C. albicans that determine its invasiveness potential, suggesting that microorganisms can sense and respond to the mesoporous surface. Our findings demonstrate the efficiency of a simple chemical oxidative treatment in generating nanotextured surfaces with antimicrobial capacity with potential applications in the implant manufacturing industry and hospital setting

  2. Condensation Behavior of Ag Aggregates on Liquid Surfaces

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Fei; ZHANG Chu-Hang; LV Neng; XIE Jian-Ping; YE Gao-Xiang

    2010-01-01

    @@ We report a condensation behavior of silver aggregates on silicone oil surfaces.The deposited Ag atoms diffuse and aggregate on the oil surface,and then form granular dusters and ramified islands.The apparent Ag coverage of the total area increases linearly with the nominal film thickness h for h < 0.9 nm.However,the coverage exhibits a fluctuation behavior for 1.0 nm< h< 2.5 nm.It is found that the anomalous behavior of the coverage is resulted from a characteristic material condensation process in the aggregates.

  3. Microscale Imaging: Microbial Behavior Near NAPL Surfaces

    Science.gov (United States)

    Singh, R.; Xu, M.; Olson, M. S.

    2006-12-01

    A comprehensive understanding of microbial transport mechanisms is needed for effective in situ bioremediation of ground water contaminants. Microscale imaging has great potential to provide insight into microbial transport and behavior in subsurface water near contaminated sites. In the present study we focus on the application of two novel microscale imaging techniques to observe microbial behavior surrounding dissolving NAPL in porous media: we use micro-CT to quantify bioenhancement of NAPL dissolution and we use two-color molecular probes to observe NAPL toxicity at the NAPL/water interface using fluorescence microscopy. Microcomputed Tomography (micro-CT) is a non-invasive imaging technique that allows visualization and quantification of the internal features of objects and porous media. The dissolution rate of TCE droplets dispersed in 1-mm-diameter glass beads was compared for water-saturated beads and beads containing an aqueous suspension of Pseudomonas putida F1. Changing volumes of NAPL ganglia were measured over time using micro-CT, and used to compute the mass transfer rate coefficient of TCE, with and without microbial degradation. Comparison of the mass transfer rate coefficients of TCE will be discussed. In addition, a novel method was developed to image both chemotaxis and the toxic effect of a dissolving NAPL droplet on the surrounding population of P. putida F1. Chemotaxis refers to the movement of bacteria under the influence of chemical gradient (either away or toward), which helps them to find an optimal concentration for their growth and survival. Agarose plug assays, in combination with a two-color fluorescence assay of bacterial viability, were used for investigation. Bacteria were stained with a mixture of SYTO 9 nucleic acid stain and propidium iodide. The stained bacterial solution was flooded into a chamber formed around an agarose plug containing TCE. Bacterial chemotactic response to TCE dissolution was measured by imaging the

  4. Contribution of Long Fibrils and Peptides to Surface and Foaming Behavior of Soy Protein Fibril System

    NARCIS (Netherlands)

    Wan, Zhili; Yang, Xiaoquan; Sagis, L.M.C.

    2016-01-01

    When soy glycinin (11S) is heated for a prolonged time at pH 2 (20 h at 85 °C), a mixture is formed consisting of long semiflexible 11S fibrils and small peptides. The surface and foaming properties of this mixture were investigated at different pHs, and compared to the behavior of pure fibrils and

  5. Calculation of structurally related properties of bulk and surface Si

    International Nuclear Information System (INIS)

    The self-consistent pseudopotential method is applied to study the bulk and surface structurally related properties of Si. Equilibrium configurations are determined by minimizing the total energy of the system; the calculated bulk properties and the surface relaxation of Si are found to be in good agreement with experiment. The surface energy and the surface reconstruction of Si are briefly discussed

  6. Collective properties and strong coupling in the near-field of a meta-surface

    Science.gov (United States)

    Felbacq, Didier

    2015-08-01

    Meta{surfaces or 2D metamaterials are generally seen as a device able to control the far-field behavior of light. Several studies have shown the possibility of controlling the polarization state, the directivity, the light-by-light manipulation or the generation of second harmonic signal. However, because of their resonant properties, meta{ surfaces also have interesting properties in the near-field. In the present work, a meta{surface made of a set of parallel line distributed dipoles was studied. The coupling of a quantum emitter with the photonic surface modes supported by the meta{surface is investigated.

  7. Synthetic melanin films: Assembling mechanisms, scaling behavior, and structural properties

    Science.gov (United States)

    Lorite, Gabriela S.; Coluci, Vitor R.; da Silva, Maria Ivonete N.; Dezidério, Shirlei N.; Graeff, Carlos Frederico O.; Galva~O, Douglas S.; Cotta, Mônica A.

    2006-06-01

    In this work we report on the surface characterization of melanin thin films prepared using both water-based and organic solvent-based melanin syntheses. Atomic force microscopy (AFM) analysis of these films suggests that the organic solvent synthesis provides relatively planar basic melanin structures; these basic structures generate surface steps with height in the range of 2-3 nm and small tendency to form larger aggregates. The scaling properties obtained from the AFM data were used to infer the assembling mechanisms of these thin films which depend on the solvent used for melanin synthesis. The behavior observed in organic solvent-based melanin suggests a diffusion-limited aggregation process. Thus films with good adhesion to the substrate and smoother morphologies than water-prepared melanin films are obtained. Electronic structure calculations using a conductorlike screening model were also performed in order to elucidate the microscopic processes of thin film formation. Our results suggest that the agglomerates observed in hydrated samples originate from reaction with water at specific locations on the surface most likely defects on the planar structure.

  8. Electrical properties of surface functionalized silicon nanoparticles

    International Nuclear Information System (INIS)

    The present study relates to the applicability of silicon nanoparticles as basic component in printing inks for the fabrication of printable electronic devices. It is systematically investigated, how the surface functionalization of silicon nanoparticles with 1-alkenes affects the electrical properties of thin films made of them. Therefore, films of as-prepared silicon nanoparticles with a size of 42 nm as well as freshly etched ones, both terminated with hydrogen, are compared with films of silicon nanoparticles functionalized with n-octene, n-dodecene, allylmercaptan, and allylamine, respectively. It is found, that the activation energy of the electron transport through the films is in the range of 0.5 eV and scales with the polarity of the functionalization.

  9. 乙酸乙酯-异丙醇二元系的黏度行为和表面性质%Viscous behavior and surface properties of binary mixture of ethyl acetate and isopropanol

    Institute of Scientific and Technical Information of China (English)

    凌锦龙; 徐敏虹; 俞丽丽

    2012-01-01

    The viscosity (77) and surface tension (σ) of ethyl acetate (EA) + isopropanol (IPA) binary mixture were measured over the entire composition range at 298. 15-323. 15 K and atmospheric pressure using Ubbelohde viscometer and pendant drop method, respectively. Viscosity deviations (Δ η)> excess Gibbs energy of activation of viscous flow (ΔG*E) and surface tension deviations (Δσ) were calculated from the experimental data. The excess thermodynamic properties, A17, AG*E and Act were correlated by the Redlich-Kister equation, and fitted parameters and standard deviations were obtained. The results show that Δη, ΔG*E and Δσ are negative over the whole mole fraction range in the temperature range studied, and all deviations become larger as temperature decreases. The surface tension values were further used to calculate the surface entropies (Ss) and surface enthalpies ( Hs) per unit surface area. The lyophobicity (β) and the surface mole fraction (x2s) of IPA were also derived using the extended Langmuir model. The obtained x2s values indicate that the surface concentration of IPA is always higher than its bulk concentration and consequently confirm that the surface is enriched with IPA.%常压下测定了乙酸乙酯和异丙醇二元系在298.15~323.15 K下的黏度和表面张力,计算了黏度偏差、过量流动活化自由能和表面张力偏差,采用Redlich-Kister方程进行了关联.结果表明,黏度偏差、过量流动活化自由能和表面张力偏差均为负值,且显示了相同的变化趋势,随温度降低而偏差增大.利用表面张力数据进一步考察了混合液表面熵和表面焓,并基于扩展的Langmuir模型,计算了异丙醇的疏液性β及其表面组成.β值表明异丙醇对表面有更大的亲和力,其表面组成始终高于在溶液本体中的组成.

  10. Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water

    Institute of Scientific and Technical Information of China (English)

    LIANG Jin-sheng; MENG Jun-ping; LIANG Guang-chuan; WANG Li-juan; ZHANG Jin; LI Ji-yuan

    2006-01-01

    A super-hydrophilic functional ceramic was prepared by adjusting the chemical components of ceramic glaze. Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water were studied. The results show that water can spread on ceramic surface with high surface free energy,and oil droplet can aggregate rapidly and separate from the ceramic surface in water. For the ceramic with lower surface free energy,the polar shares are dependant on its easy-cleaning property. The higher the polar shares,the better the easy-cleaning property,and the easier the droplet separates from the ceramic surface in water.

  11. Electrodynamics simulations of surface plasmon behavior in metallic nanostructures

    International Nuclear Information System (INIS)

    Realistic finite-difference time-domain simulations are carried to learn how to understand and control localized surface plasmons (LSP's) and traveling surface plasmon polaritons (SPP's) in metallic nanostructures. We show how to control the spatio-temporal behavior of LSP hot spots in cone-shaped metal nanoparticles. We discuss how to intensify and lengthen SPP's in thin metallic films. Finally, we discuss the relative roles of LSP's and SPP's in thin metal films with nanoscale holes and slits.

  12. Stochastic and fractal properties of silicon and porous silicon rough surfaces

    International Nuclear Information System (INIS)

    In this paper, we investigate the stochastic properties and fractal behavior of Si and porous silicon (PS) rough surfaces to characterize the complexity of their morphology. To this end, height fluctuations of these rough surfaces are determined by Atomic Force Microscopy (AFM) and then roughness and correlation length of the surfaces are calculated. The generalized Hurst exponent, h(q) and singularity spectrum, f(α) are obtained by using two dimensional MF-DFA method for both rough surfaces; Our results show that both mentioned surfaces are multifractal and have different scaling exponents. To investigate the reason of the observed multifractality behavior, we determine height distribution, skewness and kurtosis measures and show that the deviation from the Gaussian distribution for the height fluctuations of the surfaces can be a reason for the observed multifractality behavior

  13. Self-propelled droplet behavior during condensation on superhydrophobic surfaces

    Science.gov (United States)

    Chu, Fuqiang; Wu, Xiaomin; Zhu, Bei; Zhang, Xuan

    2016-05-01

    Self-propelled droplet motion has applications in various engineering fields such as self-cleaning surfaces, heat transfer enhancement, and anti-icing methods. A superhydrophobic surface was fabricated using two simultaneous chemical reactions with droplet condensation experiments performed on the horizontal superhydrophobic surface to characterize the droplet behavior. The droplet behavior is classified into three types based on their motion features and leftover marks as immobile droplet coalescence, self-propelled droplet jumping, and self-propelled droplet sweeping. This study focuses on the droplet sweeping that occurs due to the ultra-small rolling angle of the superhydrophobic surface, where the resulting droplet sweeps along the surface, merging with all the droplets it meets and leaving a long, narrow, clear track with a large droplet at the end of the track. An easy method is developed to predict the droplet sweeping direction based on the relative positions of the droplets just before coalescence. The droplet sweeping always absorbs dozens of droplets and is not limited by the surface structures; thus, this sweeping has many useful applications. In addition, the relationships between the droplet behavior and the number of participating droplets are also analyzed statistically.

  14. Effect of Surface Modification on Behaviors of Cerium Oxide Nanopowders

    Institute of Scientific and Technical Information of China (English)

    Li Mei; Shi Zhenxue; Liu Zhaogang; Hu Yanhong; Wang Mitang; Li Hangquan

    2007-01-01

    Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders. A surfactant-sodium dodecyl sulfate(C12H25SO4Na) was used to modify the surface of CeO2 powder particles. The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester, laser particle size analyzer, specific surface area tester, X-ray diffraction tester, and a scanning electron microscope. The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity, and decrease the specific surface area and agglomeration of CeO2 powders. The mechanism of the surface modification of CeO2 powder particles was also discussed.

  15. Surface properties and fatigue limit of metal. Communication 2. Heterogeneity of properties on surface

    International Nuclear Information System (INIS)

    Besides well-known data the structural studies of microhardness variation permit estimating heterogeneity of properties on the surface of specimens of 20Kh13, 15Kh12N2VMF, 08Kh17N16T steel and VT3-1 titanium alloy. Microhardness for these materials varies within the range ±20% of the average value. Cracks under cyclic loading are initiated in the zones with minimal microhardness. Grain size for all materials is 0.001...0.015 mm

  16. Influence of Stimulus Properties and Sensory Task Instructions on Oral Processing Behavior of Liquid Stimuli

    NARCIS (Netherlands)

    Derks, J.A.M.; Wijk, De R.A.; Graaf, de Kees; Stieger, M.

    2016-01-01

    This study determined the influence of texture properties and sensory task instructions on oral processing behavior of liquid stimuli. Oral processing of one sip of water, skimmed milk, thickened skimmed milk, cream and cream with poppy seeds was quantified using Surface Electromyography. Oral be

  17. Systematic model behavior of adsorption on flat surfaces

    OpenAIRE

    Trasca, Raluca A.; Cole, Milton W.; Diehl, Renee D.

    2003-01-01

    A low density film on a flat surface is described by an expansion involving the first four virial coefficients. The first coefficient (alone) yields the Henry's law regime, while the next three correct for the effects of interactions. The results permit exploration of the idea of universal adsorption behavior, which is compared with experimental data for a number of systems.

  18. Influence of microwave irradiation on ilmenite surface properties

    Energy Technology Data Exchange (ETDEWEB)

    Nuri, Omid Salmani; Mehdilo, Akbar; Irannajad, Mehdi, E-mail: iranajad@aut.ac.ir

    2014-08-30

    Graphical abstract: - Highlights: • Microwave irradiation converts Fe{sup 2+} to Fe{sup 3+} ions on ilmenite surface. • Fe{sup 3+} ions react with oleate ions forming Fe(Ol){sub 3} layer more stable than Fe(Ol){sub 2} layer. • The more oleate adsorption after irradiation improves the ilmenite hydrophobicity. • The study of ilmenite surface by XPS, FTIR, zeta and contact angle measurement. - Abstract: In this study, the effect of microwave irradiation on ilmenite surface properties and its flotation behavior was investigated. After microwave irradiation, Fe{sup 2+} ions on the ilmenite surface are oxidized to Fe{sup 3+} ions. XPS analysis indicated that the relative content of Fe{sup 3+} increased from 48.5% to 66% after microwave irradiation for 2.5 min. This conversion decreased the ilmenite surface zeta potential in a wide pH range and resulted in the shift of PZC from a pH of 5.4 to a pH of 2.7. FTIR spectra and zeta potential measurements showed that the microwave irradiation enhances the adsorption of oleate ions on the ilmenite Helmholtz layer. The greater stability of chemisorbed ferric iron oleate than ferrous iron oleate resulted in the increase of contact angle and the decrease of surface zeta potential. Therefore, the microwave irradiation pretreatment improves the ilmenite hydrophobicity and floatability in a wide pH range. The maximum floatability of ilmenite occurring at a pH of 6.3 was 73.5% and 94% for non-irradiated and irradiated ilmenite, respectively.

  19. Droplet impact behavior on heated micro-patterned surfaces

    Science.gov (United States)

    Zhang, Wenbin; Yu, Tongxu; Fan, Jing; Sun, Weijie; Cao, Zexian

    2016-03-01

    Impact behavior of droplets on a surface is an intriguing research topic, and its control should be very useful in diverse industrial applications. We investigated the impact behavior of water droplets on the textured and chemically treated surface of silicon and obtained the impact mode map on the parameter plane subtended by the Weber number (up to 85) and temperature (up to 320 °C). The patterns comprise of micropillars (14 μm in height) in square lattice with a lattice constant of 10 and 20 μm, and the surface was further made superhydrophobic by coating with graphene nanosheets. Six distinct impact modes are identified. It was found that the impact mode map can be dramatically altered by modifying the texture and chemistry of the surface, and the observations are well explained with regard to heat transfer, vapor/bubble generation and vapor flow beneath the droplet. Instability in the droplet arising from the mismatch between vapor generation rate and exhaust conditions is the dominant factor in determining the impact mode. Our results revealed more facts and features of the droplet impact phenomenon and can be very useful for target-oriented surface design towards precise control of droplet impact behavior on heated substrates.

  20. Frictional Behavior of Micro/nanotextured Surfaces Investigated by Atomic Force Microscope: a Review

    Science.gov (United States)

    Zhang, Xiaoliang; Jia, Junhong

    2015-08-01

    Tribological issues between friction pair are fundamental problems for minimized devices because of their higher surface-to-volume ratio. Micro/nanotexturing is an effective technique to reduce actual contact area between contact pair at the nanoscale. Micro/nanotexture made a great impact on the frictional behavior of textured surfaces. This paper summarizes the recent advancements in the field of frictional behavior of micro/nanotextured surfaces, which are based on solid surface contact in atmosphere environment, especially focusing on the factors influencing the frictional behavior: Surface property, texturing density, texturing height, texturing structure and size of contact pair (atomic force microscope (AFM) tip) and texturing structures. Summarizing the effects of these factors on the frictional behavior is helpful for the understanding and designing of the surfaces in sliding micro/nanoelectromechanical systems (MEMS/NEMS). Controlling and reducing the friction force in moving mechanical systems is very important for the performance and reliability of nanosystems, which contribute to a sustainable future.

  1. Geographic, seasonal, and diurnal surface behavior of harbor porpoises

    DEFF Research Database (Denmark)

    Teilmann, Jonas; Christiansen, C.T.; Kjellerup, Sanne;

    2013-01-01

    are essential information on the status and management of the species. Thirty-five free-ranging harbor porpoises (Phocoena phocoena) were tracked in the region between the Baltic and the North Sea for 25-349 d using Argos satellite transmitters. No differences were found in surface behavior between...... geographical areas or the size of the animals. Slight differences were found between the two sexes and time of day. Surface time peaked in April, where 6% was spent with the transmitter above surface and 61.5% between 0 and 2 m depth, while the minimum values occurred in February (3.4% and 42.5%, respectively......). The analyses reveal that individual variation among porpoises is the most important factor in explaining variation in surface rates. However, the large number of animals documented in the present study covering a wide range of age and sex groups justifies the use of the seasonal average surface times...

  2. Ofstatistical and Fractal Properties of Semiconductor Surface Roughness

    Directory of Open Access Journals (Sweden)

    Stanislav Jurecka

    2008-01-01

    Full Text Available Surface morphology evolution is of primary significance for the thin-film growth and modification of surface andinterface states. Surface and interface states substantially influence the electrical and optical properties of the semiconductorstructure. Statistical and fractal properties of semiconductor rough surfaces were determined by analysis of the AFM images.In this paper statistical characteristics of the AFM height function distribution, fractal dimension, lacunarity and granulometric density values are used for the surface morphology of the SiC samples description. The results can be used for solution ofthe microstructural and optical properties of given semiconductor structure.

  3. Osteoblast Behavior on Hierarchical Micro-/Nano-Structured Titanium Surface

    Institute of Scientific and Technical Information of China (English)

    Weiyan Meng; Yanmin Zhou; Yanjing Zhang; Qing Cai; Liming Yang; Jinghui Zhao; Chnnyan Li

    2011-01-01

    In the present work, osteoblast behavior on a hierarchical micro-/nano-structured titanium surface was investigated. A hierarchical hybrid micro-/nano-structured titanium surface topography was produced via Electrolytic Etching (EE). MG-63 cells were cultured on disks for 2 h to 7 days. The osteoblast response to the hierarchical hybrid micro-/nano-structured titanium surface was evaluated through the osteoblast cell morphology, attachment and proliferation. For comparison, MG-63 cells were also cultured on Sandblasted and Acid-etched (SLA) as well as Machined (M) surfaces respectively. The results show significant differences in the adhesion rates and proliferation levels of MG-63 cells on EE, SLA, and M surfaces. Both adhesion rate and proliferation level on EE surface are higher than those on SLA and M surfaces. Therefore, we may expect that, comparing with SLA and M surfaces, bone growth on EE surface could be accelerated and bone formation could be promoted at an early stage, which could be applied in the clinical practices for immediate and early-stage loadings.

  4. Dynamic superhydrophobic behavior in scalable random textured polymeric surfaces

    Science.gov (United States)

    Moreira, David; Park, Sung-hoon; Lee, Sangeui; Verma, Neil; Bandaru, Prabhakar R.

    2016-03-01

    Superhydrophobic (SH) surfaces, created from hydrophobic materials with micro- or nano- roughness, trap air pockets in the interstices of the roughness, leading, in fluid flow conditions, to shear-free regions with finite interfacial fluid velocity and reduced resistance to flow. Significant attention has been given to SH conditions on ordered, periodic surfaces. However, in practical terms, random surfaces are more applicable due to their relative ease of fabrication. We investigate SH behavior on a novel durable polymeric rough surface created through a scalable roll-coating process with varying micro-scale roughness through velocity and pressure drop measurements. We introduce a new method to construct the velocity profile over SH surfaces with significant roughness in microchannels. Slip length was measured as a function of differing roughness and interstitial air conditions, with roughness and air fraction parameters obtained through direct visualization. The slip length was matched to scaling laws with good agreement. Roughness at high air fractions led to a reduced pressure drop and higher velocities, demonstrating the effectiveness of the considered surface in terms of reduced resistance to flow. We conclude that the observed air fraction under flow conditions is the primary factor determining the response in fluid flow. Such behavior correlated well with the hydrophobic or superhydrophobic response, indicating significant potential for practical use in enhancing fluid flow efficiency.

  5. Chemical, electronic, and magnetic structure of LaFeCoSi alloy: Surface and bulk properties

    International Nuclear Information System (INIS)

    We investigate the chemical, electronic, and magnetic structure of the magnetocaloric LaFeCoSi compound with bulk and surface sensitive techniques. We put in evidence that the surface retains a soft ferromagnetic behavior at temperatures higher than the Curie temperature of the bulk due to the presence of Fe clusters at the surface only. This peculiar magnetic surface effect is attributed to the exchange interaction between the ferromagnetic Fe clusters located at the surface and the bulk magnetocaloric alloy, and it is used here to monitor the magnetic properties of the alloy itself.

  6. A Method to Simulate the Observed Surface Properties of Proton Irradiated Silicon Strip Sensors

    CERN Document Server

    Peltola, Timo Hannu Tapani

    2014-01-01

    A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching to measurements of silicon strip detectors. However, the model does not provide the expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detector's...

  7. Nonfouling property of zwitterionic cysteine surface.

    Science.gov (United States)

    Lin, Peter; Ding, Ling; Lin, Chii-Wann; Gu, Frank

    2014-06-10

    Applications of implantable bioelectronics for analytical and curative purposes are currently limited by their poor long-term biofunctionality in physiological media and nonspecific interactions with biomolecules. In an attempt to prolong in vivo functionality, recent advances in surface modifications have demonstrated that zwitterionic coatings can rival the performance of conventional poly(ethylene glycol) polymers in reducing nonspecific protein fouling. Herein, we report the fabrication of a very thin layer of nonfouling zwitterionic cysteine surface capable of protecting implantable bioelectronics from nonspecific adsorption of plasma proteins. This work is the first of its kind to fabricate, through solution chemistry, a cysteine surface exhibiting zwitterionic state as high as 88% and to demonstrate antibiofouling under the exposure of bovine serum albumin (BSA) and human serum. The fabricated surface utilized a minimal amount of gold substrate, approximately 10 nm, and an extremely thin antifouling layer at 1.14 nm verified by ellipsometry. X-ray photoelectron spectroscopy assessment of the nitrogen (N1s) and carbon (C1s) spectra conclude that 87.8% of the fabricated cysteine surface is zwitterionic, 2.5% is positively charged, and 9.6% is noncharged. Antibiofouling performance of the cysteine surface is quantitatively determined by bicinchoninic acid (BCA) protein assay as well as qualitatively confirmed using scanning electron spectroscopy. Cysteine surfaces demonstrated a BSA fouling of 3.9 ± 4.84% μg/cm(2), which is 93.6% and 98.5% lower than stainless steel and gold surfaces, respectively. Surface plasmon resonance imaging analysis returned similar results and suggest that a thinner cysteine coating will enhance performance. Scanning electron microscopy confirmed the results of BCA assay and suggested that the cysteine surface demonstrated a 69% reduction to serum fouling. The results reported in this paper demonstrate that it is possible to achieve

  8. Contribution of Long Fibrils and Peptides to Surface and Foaming Behavior of Soy Protein Fibril System.

    Science.gov (United States)

    Wan, Zhili; Yang, Xiaoquan; Sagis, Leonard M C

    2016-08-16

    When soy glycinin (11S) is heated for a prolonged time at pH 2 (20 h at 85 °C), a mixture is formed consisting of long semiflexible 11S fibrils and small peptides. The surface and foaming properties of this mixture were investigated at different pHs, and compared to the behavior of pure fibrils and pure peptides, to determine the individual contributions of these two factions to the behavior of the mixture. The adsorption of these three systems at air-water interfaces and the resulting surface rheological properties were studied by combining drop shape analysis tensiometry, ellipsometry, and surface large amplitude oscillatory dilatational (LAOD) rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. Our results show that the adsorption kinetics, dilatational rheological properties, and the foaming behavior of the mixture were mainly dominated by the small peptides in the fibril system. Compared to pH 2, the fibril mixture at pH 5 and 7 provides much better foam stability and appears to be a very promising protein material to make stable foams, even at low protein concentration (0.1 wt %). The presence of fibril clusters and peptide aggregates at pH 5 and 7 contributed to foam stability of the mixture. In contrast, pure fibril formed an interface with a highly pH-responsive adsorption and rheological behavior, and the foamability and foam stability of the pure fibrils were very poor. PMID:27452662

  9. Properties modification of nanopatterned surfaces functionalized with photo activated ligands

    OpenAIRE

    Stoianov, Stefan Vladimirov

    2011-01-01

    This dissertation focuses on four research topics: self-assembly of colloidal nanoparticles, surface modifications of the properties of ionically self-assembled multilayer films, surface enhanced Raman spectroscopy of functionalized gold nanoparticles, and two photon uncaging in gel. Those techniques are used for development of novel nanofabrication methods for top-down and bottom-up assembly of nanostructures, by modifying the properties of nanopatterned surfaces with photoactive ligands, an...

  10. Probing Anisotropic Surface Properties of Molybdenite by Direct Force Measurements.

    Science.gov (United States)

    Lu, Zhenzhen; Liu, Qingxia; Xu, Zhenghe; Zeng, Hongbo

    2015-10-27

    Probing anisotropic surface properties of layer-type mineral is fundamentally important in understanding its surface charge and wettability for a variety of applications. In this study, the surface properties of the face and the edge surfaces of natural molybdenite (MoS2) were investigated by direct surface force measurements using atomic force microscope (AFM). The interaction forces between the AFM tip (Si3N4) and face or edge surface of molybdenite were measured in 10 mM NaCl solutions at various pHs. The force profiles were well-fitted with classical DLVO (Derjaguin-Landau-Verwey-Overbeek) theory to determine the surface potentials of the face and the edge surfaces of molybdenite. The surface potentials of both the face and edge surfaces become more negative with increasing pH. At neutral and alkaline conditions, the edge surface exhibits more negative surface potential than the face surface, which is possibly due to molybdate and hydromolybdate ions on the edge surface. The point of zero charge (PZC) of the edge surface was determined around pH 3 while PZC of the face surface was not observed in the range of pH 3-11. The interaction forces between octadecyltrichlorosilane-treated AFM tip (OTS-tip) and face or edge surface of molybdenite were also measured at various pHs to study the wettability of molybdenite surfaces. An attractive force between the OTS-tip and the face surface was detected. The force profiles were well-fitted by considering DLVO forces and additional hydrophobic force. Our results suggest the hydrophobic feature of the face surface of molybdenite. In contrast, no attractive force between the OTS-tip and the edge surface was detected. This is the first study in directly measuring surface charge and wettability of the pristine face and edge surfaces of molybdenite through surface force measurements. PMID:26434695

  11. Dendritic Cell Responses to Surface Properties of Clinical Titanium Surfaces

    OpenAIRE

    Kou, Peng Meng; Schwartz, Zvi; Boyan, Barbara D; Babensee, Julia E.

    2010-01-01

    Dendritic cells (DCs) play pivotal roles in responding to foreign entities during an innate immune response and initiating effective adaptive immunity as well as maintaining immune tolerance. The sensitivity of DCs to foreign stimuli also makes them useful cells to assess the inflammatory response to biomaterials. Elucidating the material property-DC phenotype relationships using a well-defined biomaterial system is expected to provide criteria for immuno-modulatory biomaterial design. Clinic...

  12. Antifouling polymer brushes displaying antithrombogenic surface properties

    Czech Academy of Sciences Publication Activity Database

    de los Santos Pereira, Andres; Sheikh, S.; Blaszykowski, C.; Pop-Georgievski, Ognen; Fedorov, K.; Thompson, M.; Rodriguez-Emmenegger, Cesar

    2016-01-01

    Roč. 17, č. 3 (2016), s. 1179-1185. ISSN 1525-7797 R&D Projects: GA ČR(CZ) GJ15-09368Y; GA MŠk(CZ) ED1.1.00/02.0109 Grant ostatní: OPPK(XE) CZ.2.16/3.1.00/21545 Institutional support: RVO:61389013 Keywords : polymer brushes * surface characterization * antifouling surfaces Subject RIV: BO - Biophysics Impact factor: 5.750, year: 2014

  13. Molecular dynamics for lateral surface adhesion and peeling behavior of single-walled carbon nanotubes on gold surfaces

    International Nuclear Information System (INIS)

    Highlights: ► Adhesion and peeling behaviors of SWCNTs are investigated by detailed, fully atomistic MD simulations. ► Adhesion energy of SWCNTs are discussed. ► Dynamical behaviors of SWCNTs in low temperature adhesion are analyzed. ► Adhesion strengths of SWCNTs obtained from MD simulations are compared with the predictions of Hamaker theory and JKR model. - Abstract: Functional gecko-inspired adhesives have attracted a lot of research attention in the last decade. In this work, the lateral surface adhesion and normal peeling-off behavior of single-walled carbon nanotubes (SWCNTs) on gold substrates are investigated by performing detailed, fully atomistic molecular dynamics (MD) simulations. The effects of the diameter and adhered length of CNTs on the adhesive properties were systematically examined. The simulation results indicate that adhesion energies between the SWCNTs and the Au surface varied from 220 to 320 mJ m−2 over the reported chirality range. The adhesion forces on the lateral surface and the tip of the nanotubes obtained from MD simulations agree very well with the predictions of Hamaker theory and Johnson–Kendall–Roberts (JKR) model. The analyses of covalent bonds indicate that the SWCNTs exhibited excellent flexibility and extensibility when adhering at low temperatures (∼100 K). This mechanism substantially increases adhesion time compared to that obtained at higher temperatures (300–700 K), which makes SWCNTs promising for biomimetic adhesives in ultra-low temperature surroundings.

  14. Molecular dynamics for lateral surface adhesion and peeling behavior of single-walled carbon nanotubes on gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Pei-Hsing, E-mail: phh@mail.npust.edu.tw [Department of Mechanical Engineering, National Pingtung University of Science and Technology, Pingtung 912, Taiwan (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Adhesion and peeling behaviors of SWCNTs are investigated by detailed, fully atomistic MD simulations. Black-Right-Pointing-Pointer Adhesion energy of SWCNTs are discussed. Black-Right-Pointing-Pointer Dynamical behaviors of SWCNTs in low temperature adhesion are analyzed. Black-Right-Pointing-Pointer Adhesion strengths of SWCNTs obtained from MD simulations are compared with the predictions of Hamaker theory and JKR model. - Abstract: Functional gecko-inspired adhesives have attracted a lot of research attention in the last decade. In this work, the lateral surface adhesion and normal peeling-off behavior of single-walled carbon nanotubes (SWCNTs) on gold substrates are investigated by performing detailed, fully atomistic molecular dynamics (MD) simulations. The effects of the diameter and adhered length of CNTs on the adhesive properties were systematically examined. The simulation results indicate that adhesion energies between the SWCNTs and the Au surface varied from 220 to 320 mJ m{sup -2} over the reported chirality range. The adhesion forces on the lateral surface and the tip of the nanotubes obtained from MD simulations agree very well with the predictions of Hamaker theory and Johnson-Kendall-Roberts (JKR) model. The analyses of covalent bonds indicate that the SWCNTs exhibited excellent flexibility and extensibility when adhering at low temperatures ({approx}100 K). This mechanism substantially increases adhesion time compared to that obtained at higher temperatures (300-700 K), which makes SWCNTs promising for biomimetic adhesives in ultra-low temperature surroundings.

  15. Flexural Behavior of HPFRCC Members with Inhomogeneous Material Properties

    Directory of Open Access Journals (Sweden)

    Kyung-Joon Shin

    2015-04-01

    Full Text Available In this paper, the flexural behavior of High-performance Fiber-Reinforced Cementitious Composite (HPFRCC has been investigated, especially focusing on the localization of cracks, which significantly governs the flexural behavior of HPFRCC members. From four points bending tests with HPFRCC members, it was observed that almost evenly distributed cracks formed gradually, followed by a localized crack that determined the failure of the members. In order to investigate the effect of a localized crack on the flexural behavior of HPFRCC members, an analytical procedure has been developed with the consideration of intrinsic inhomogeneous material properties of HPFRCC such as cracking and ultimate tensile strengths. From the comparison, while the predictions with homogeneous material properties overestimated flexural strength and ductility of HPFRCC members, it was found that the analysis results considering localization effect with inhomogeneous material properties showed good agreement with the test results, not only the flexural strength and ductility but also the crack widths. The test results and the developed analysis procedure presented in this paper can be usefully applied for the prediction of flexural behaviors of HPFRCC members by considering the effect of localized cracking behavior.

  16. Pdf modeling for premixed turbulent combustion based on the properties of iso-concentration surfaces

    Science.gov (United States)

    Vervisch, L.; Kollmann, W.; Bray, K. N. C.; Mantel, T.

    1994-01-01

    In premixed turbulent flames the presence of intense mixing zones located in front of and behind the flame surface leads to a requirement to study the behavior of iso-concentration surfaces defined for all values of the progress variable (equal to unity in burnt gases and to zero in fresh mixtures). To support this study, some theoretical and mathematical tools devoted to level surfaces are first developed. Then a database of direct numerical simulations of turbulent premixed flames is generated and used to investigate the internal structure of the flame brush, and a new pdf model based on the properties of iso-surfaces is proposed.

  17. Microstructure and Mechanical Property of Ni Metal Treated by Surface Mechanical Attrition

    Institute of Scientific and Technical Information of China (English)

    Wen Chun-sheng; Rong Yong-hua; T.Y. Hsu (Xu Zu-yao)

    2004-01-01

    A nanostructured surface layer can be formed in Ni metal treated by surface mechanical attrition (SMA). The microstructure was investigated by using optical microscope, X-ray diffractometer and transmission electron microscope,respectively. Mechanical property measurements indicate that the yield strength of the surface layer raises significantly while the tensile strength somewhat changes and the elongation percentage reduces severely compared with that of the inside layer. Meanwhile, yield-drop-like phenomenon occurs in the surface layer after SMA treatment. In order to compare the mechanical behavior of nanostructured materials with two phases, Fe-30Ni nanostructured alloy was also investigated.

  18. Spectrophotometric Properties of Gaspra’s Surface

    Science.gov (United States)

    Domingue, Deborah L.; Vilas, Faith; Stockstill-Cahill, Karen; Cahill, Joshua; Hendrix, Amanda

    2015-11-01

    Using the shape-model derived for Gaspra [1] we calculate the local incidence, emission, and phase angles on a pixel-by-pixel basis for the color image sets (164 m/px spatial resolution) acquired by the Galileo Solid State Imager (SSI) [2]. Using these geometric values, we derive a disk-resolved photometric correction for application to the to the spectral data set for more accurate regional examination of mineralogy and weathering across the surface. We use regional variations in color ratios of Gaspra’s surface to examine the degree of space weathering incurred upon the surface, and find subtle variations across its surface. Using mixing modeling methods that account for submicroscopic components, we examine evidence for space weathering variations correlated to composition and grain size. We note evidence of a young surface, with only moderate modification by space weathering processes. SSI radiometrically-calibrated data combined with shape-model derived incidence, emission, and phase angle backplanes have been archived in the Planetary Data System for broader use by the community [3, 4].[1] P. Thomas et al. 1994, Icarus 107, 23 - 36. [2] M. Belton et al. 1992, Science 257, 1647 - 1652. [3] D. Domingue 2015, Galileo SSI/Gaspra Radiometrically Calibrated Images V1.0. NASA PDS. [4] D. Domingue 2015, Galileo SSI/Gaspra Color and Geometry Image Cubes V1.0. NASA PDS, submitted.

  19. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    Energy Technology Data Exchange (ETDEWEB)

    Ion, Raluca [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Vizireanu, Sorin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Stancu, Claudia Elena [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Leibniz Institute for Plasma Science and Technology (INP Greifswald), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany); Luculescu, Catalin [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania); Cimpean, Anisoara, E-mail: anisoara.cimpean@bio.unibuc.ro [University of Bucharest, Department of Biochemistry and Molecular Biology, 91-95 Spl. Independentei, 050095 Bucharest (Romania); Dinescu, Gheorghe [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor, PO Box MG-36, 077125, Magurele, Bucharest (Romania)

    2015-03-01

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N{sub 2} and O{sub 2} plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O{sub 2} plasma treatment of CNW leads to a more activated macrophage phenotype.

  20. Surface plasma functionalization influences macrophage behavior on carbon nanowalls

    International Nuclear Information System (INIS)

    The surfaces of carbon nanowall samples as scaffolds for tissue engineering applications were treated with oxygen or nitrogen plasma to improve their wettability and to functionalize their surfaces with different functional groups. X-ray photoelectron spectroscopy and water contact angle results illustrated the effective conversion of the carbon nanowall surfaces from hydrophobic to hydrophilic and the incorporation of various amounts of carbon, oxygen and nitrogen functional groups during the treatments. The early inflammatory responses elicited by un-treated and modified carbon nanowall surfaces were investigated by quantifying tumor necrosis factor-alpha and macrophage inflammatory protein-1 alpha released by attached RAW 264.7 macrophage cells. Scanning electron microscopy and fluorescence studies were employed to investigate the changes in macrophage morphology and adhesive properties, while MTT assay was used to quantify cell proliferation. All samples sustained macrophage adhesion and growth. In addition, nitrogen plasma treatment was more beneficial for cell adhesion in comparison with un-modified carbon nanowall surfaces. Instead, oxygen plasma functionalization led to increased macrophage adhesion and spreading suggesting a more activated phenotype, confirmed by elevated cytokine release. Thus, our findings showed that the chemical surface alterations which occur as a result of plasma treatment, independent of surface wettability, affect macrophage response in vitro. - Highlights: • N2 and O2 plasma treatments alter the CNW surface chemistry and wettability. • Cells seeded on CNW scaffolds are viable and metabolically active. • Surface functional groups, independent of surface wettability, affect cell response. • O2 plasma treatment of CNW leads to a more activated macrophage phenotype

  1. Ergodic properties and thermodynamic behavior of elementary reversible cellular automata. I. Basic properties

    International Nuclear Information System (INIS)

    This is the first part of a series devoted to the study of thermodynamic behavior of large dynamical systems with the use of a family of full-discrete and conservative models named elementary reversible cellular automata (ERCAs). In this paper, basic properties such as conservation laws and phase space structure are investigated in preparation for the later studies. ERCAs are a family of one-dimensional reversible cellular automata having two Boolean variables on each site. Reflection and Boolean conjugation symmetries divide them into 88 equivalence classes. For each rule, additive conserved quantities written in a certain form are regarded as a kind of energy, if they exist. By the aid of the discreteness of the variables, every ERCA satisfies the Liouville theorem or the preservation of phase space volume. Thus, if an energy exists in the above sense, statistical mechanics of the model can formally be constructed. If a locally defined quantity is conserved, however, it prevents the realization of statistical mechanics. The existence of such a quantity is examined for each class and a number of rules which have at least one energy but no local conservation laws are selected as hopeful candidates for the realization of thermodynamic behavior. In addition, the phase space structure of ERCAs is analyzed by enumerating cycles exactly in the phase space for systems of comparatively small sizes. As a result, it is revealed that a finite ERCA is not ergodic, that is, a large number of orbits coexist on an energy surface. It is argued that this fact does not necessarily mean the failure of thermodynamic behavior on the basis of an analogy with the ergodic nature of infinite systems

  2. Structural Stability and Optical Properties of Nanomaterials with Reconstructed Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Puzder, A; Williamson, A; Reboredo, F; Galli, G

    2003-10-24

    The authors present density functional and quantum Monte Carlo calculations of the stability and optical properties of semiconductor nanomaterials with reconstructed surfaces. they predict the relative stability of silicon nanostructures with reconstructed and unreconstructed surfaces, and show that surface step geometries unique to highly curved surfaces dramatically reduce the optical gaps and decrease excitonic lifetimes. These predictions provide an explanation of both the variations in the photoluminescence spectra of colloidally synthesized nanoparticles and observed deep gap levels in porous silicon.

  3. Structural and electronic properties of hydrosilylated silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Baumer, A.

    2005-11-15

    The structural and electronic properties of alkyl-terminated Si surfaces prepared by thermallyinduced hydrosilylation have been studied in detail in the preceding chapters. Various surfaces have been used for the functionalization ranging from crystalline Si over amorphous hydrogenated Si to nanoscaled materials such as Si nanowires and nanoparticles. In each case, the alkyl-terminated surfaces have been compared to the native oxidized and H-terminated surfaces. (orig.)

  4. Optical properties of near-surface exciton quantum wells

    OpenAIRE

    N. Atenco Analco; B. Flores Desirena; A. Silva Castillo; F. Pérez Rodríguez

    2001-01-01

    An overview of theoretical investigations on near-surface semiconductor quantum wells, whose optical properties are considerably affected by the interaction of the exciton with the sample surface is given. Near-surface quantum wells with both weak and strong quantum confinement of excitons are considered. When the exciton quantum well is very close to the sample surface, exciton dynamics is determined not only by characteristics of the quantum well, but also by the interaction of the exciton ...

  5. Wetting Properties of Molecularly Rough Surfaces

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Martin; Malijevský, Alexandr; Lísal, Martin

    2015-01-01

    Roč. 143, č. 10 (2015), s. 104701. ISSN 0021-9606 R&D Projects: GA ČR GA13-09914S; GA MŠk LH12020 Institutional support: RVO:67985858 Keywords : contant-angle * solid -surface * dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.952, year: 2014

  6. Diffuse Coplanar Surface Barrier Discharge in Nitrogen: Microdischarges Statistical Behavior

    Directory of Open Access Journals (Sweden)

    Jan Cech

    2013-01-01

    Full Text Available We studied statistical behavior of microdischarges of diffuse coplanar surface barrier discharge (DCSBD operated in nitrogen atmosphere at two input voltage regimes. We measured spectrally unresolved discharge patterns together with discharge electrical parameters using highspeed iCCD camera and digital storage oscilloscope. External synchronization enabled us to measure the discharge pattern during positive and/or negative half-period of input high voltage in the single-shotmode of operation. The comparison of microdischarges behavior during positive, negative and both half periods of input high voltage was performed for two levels of input voltage, i.e. voltage slightly above ignition voltage and high above ignition voltage (“overvoltage”. The number of microchannels crossing discharge gap was counted and compared with number of microdischarge current peaks observed during corresponding half-period of input high voltage. The relations of those incidences was shown and discussed.

  7. Dynamic behavior and microstructural properties of cancellous bone

    CERN Document Server

    Laporte, Sébastien; Bousson, Valérie; Pattofatto, Stephane

    2009-01-01

    The aim of the presented study is to identify some properties of the dynamic behavior of the cancellous bone and to identify the link between this mechanical behavior and the microstructural properties. 7 cylinders of bovine cancellous bone (diameter 41 mm, thickness 14 mm) were tested in quasi static loading (0.001 s-1), 8 in dynamic loading (1000 s-1) and 10 in dynamic loading (1500 s-1) with a confinement system. All the specimens were submitted to imaging before the tests (pQCT) in order to indentify two microstructural properties: Bone Volume / Total Volume ? BV/TV ? and Trabeculae Thickness ? Tb.Th. The behavior of bovine cancellous bone under compression exhibits a foam-type behavior over the whole range of strain rates explored in this study. The results show that for the quasi-static tests only the stresses are correlated with BV/TV. For the unconfined dynamic tests, the yield stress is correlated to BV/TV and the plateau stress to BV/TV and Tb.Th. For the confined tests, only the plateau stress is c...

  8. Antibacterial properties of composite UHMWPE/ surfaces

    Science.gov (United States)

    Delle Side, D.; Nassisi, V.; Giuffreda, E.; Velardi, L.; Alifano, P.; Talà, A.; Tredici, S. M.

    2014-10-01

    Due to the diffusion of severe pathogens, everyday life is exposed to the risks of contracting severe diseases. For this reason, efficient antimicrobial surfaces are of paramount importance. In this work we present the first evidences of a new technique to obtain an antibacterial ultra high molecular weight polyethylene based on a non-stoichiometric, visible light responsive, titanium oxide coating. The coating was obtained through a process in which titanium ions, resulting from laser ablation of a corresponding target, were accelerated and implanted on the samples. The samples were tested against a Staphylococcus aureus strain, in order to assay their antimicrobial efficacy. Results show that this treatment strongly discourages bacterial colonization of the treated surfaces.

  9. Electrochemical behavior of Ni-Ti alloy after surface modification

    Directory of Open Access Journals (Sweden)

    M. Kaczmarek

    2006-08-01

    Full Text Available Purpose: The shape memory effect and superelasticity make the nickel-titanium alloy an interesting material formedical applications. But the biocompatibility has been questioned due to conflicting results in the literature.The latest research has shown that this situation may be caused by a variation in NiTi surface treatment.The appropriate surface treatment increases the corrosion resistance. The paper presents the electrochemicalbehavior of NiTi alloy after surface modification with the use of various techniques.Design/methodology/approach: The evaluation of the electrochemical behavior of NiTi alloy was realizedboth by recording of anodic polarization curves with the use of the potentiodynamic method and by anelectrochemical impedance spectroscopy technique (EIS.Findings: Surface condition of metallic biomaterial determines its corrosion resistance. In the course of thework it was observed that the lowest values of corrosion current were recorded for the sterilized and thethermally passivated samples. The highest values of corrosion current were recorded for the ground samples.These samples obviously had also the highest corrosion rate.Research limitations/implications: The obtained results are the basis for the optimization of physicochemicalproperties of the metallic biomaterial. The future research should be focused on selected specific implantsspecially with respect to their application features.Practical implications: On the basis of the obtained results it can be stated that the suggested surface treatmentcan be applicable for medical implants due to the increase of the corrosion resistance and in consequence theincrease of biocompatibility.Originality/value: The paper presents the influence of various methods of the surface treatment on corrosionresistance of the NiTi alloy. The suggested methods can be applied in treatment of the material intended formedical applications especially in cases where the surface roughness plays important

  10. Sputtering properties of redeposited graphite surfaces

    International Nuclear Information System (INIS)

    Sputtering yields for carbon redeposited films, put down in the presence of high neutral hydrogen and helium background concentrations, have been measured. The data were obtained using the ion-surface interaction system (ISIS) which is an ion beam sputtering system capable of creating redeposited films and measuring sputtering yields. Yields were determined by calibrated collection of a portion of the sputtered material onto a quartz-crystal-microbalance. Incident ion beam energies ranged from 100 eV up to 10 keV. Sputtering yields for hydrogen and helium bombardment of redeposited films created in ISIS from targets of Union Carbide ATJ graphite are reported. In addition, yields obtained from ISIS proton and deuteron bombardment of Poco AXF-5Q graphite surfaces previously modified in PISCES are also presented. Measurements of sputtering yields from pristine, bulk samples are reported for comparison. Hydrogen sputtering yields from redeposited films generated in ISIS are 2.5 times higher than those of pristine ATJ at an incident energy of 100 eV. Above 200 eV, the hydrogen yields are a factor of 1.4 higher for the redeposited material. Helium yields are 34 times greater for redeposited films at 100 eV and remain as much as 10 times greater above 500 eV. Curve-fits to the data, obtained by incorporating an effective surface binding energy for the redeposited film into a semi-empirical yield expression, are also presented. (orig.)

  11. Influence of Surface Tension on Nuclear Collective Properties

    CERN Document Server

    Goncharova, N G

    2016-01-01

    Rigidities of even-even nuclei were estimated and compared with nuclear charge radii. Correlation of maximal nuclear rigidities with minimal values of r0 parameters was revealed. Influence of effective surface tension on nuclear properties was discussed.

  12. Friction behavior of nano-textured polyimide surfaces measured by AFM colloidal probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoliang [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wu, Chunxia; Che, Hongwei; Hou, Junxian [College of Equipment Manufacturing, Hebei University of Engineering, Handan 056038 (China); Jia, Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2014-11-30

    Highlights: • Flat PI film and nano-textured PI film were prepared by spin-coating process. • The nano-textured PI surface has effectively reduced the adhesion and friction. • Friction increased with the increasing of contact area and adhesion. • The growth rate of friction decreased with the increasing of applied load. - Abstract: Flat polyimide (PI) film and silicon dioxide nanoparticle-textured PI film were prepared by means of the spin-coating technique. The adhesion and friction properties of the flat PI surface and nano-textured PI surface were investigated by a series of Atomic force microscope (AFM) colloidal probes. Experimental results revealed that the nano-textured PI surface can significantly reduce the adhesive force and friction force, compared with the flat PI surface. The main reason is that the nano-textures can reduce the contact area between the sample surface and colloidal probe. The effect of colloidal probe size on the friction behavior of the flat and nano-textured PI surfaces was evaluated. The adhesive force and friction force of nano-textured PI surface were increased with the increasing of the size of interacting pairs (AFM colloidal probe) due to the increased contact area. Moreover, the friction forces of flat and nano-textured PI surfaces were increased with applied load and sliding velocity.

  13. Friction behavior of nano-textured polyimide surfaces measured by AFM colloidal probe

    International Nuclear Information System (INIS)

    Highlights: • Flat PI film and nano-textured PI film were prepared by spin-coating process. • The nano-textured PI surface has effectively reduced the adhesion and friction. • Friction increased with the increasing of contact area and adhesion. • The growth rate of friction decreased with the increasing of applied load. - Abstract: Flat polyimide (PI) film and silicon dioxide nanoparticle-textured PI film were prepared by means of the spin-coating technique. The adhesion and friction properties of the flat PI surface and nano-textured PI surface were investigated by a series of Atomic force microscope (AFM) colloidal probes. Experimental results revealed that the nano-textured PI surface can significantly reduce the adhesive force and friction force, compared with the flat PI surface. The main reason is that the nano-textures can reduce the contact area between the sample surface and colloidal probe. The effect of colloidal probe size on the friction behavior of the flat and nano-textured PI surfaces was evaluated. The adhesive force and friction force of nano-textured PI surface were increased with the increasing of the size of interacting pairs (AFM colloidal probe) due to the increased contact area. Moreover, the friction forces of flat and nano-textured PI surfaces were increased with applied load and sliding velocity

  14. High temperature oxidation behavior of AISI 304L stainless steel—Effect of surface working operations

    International Nuclear Information System (INIS)

    Highlights: ► Surface working resulted in thinner oxide on the surface. ► Oxides on machined/ground surfaces richer in Cr, higher in specific resistivity. ► Additional ionic transport process at the metal-oxide for ground sample established. ► Presence of fragmented grains and martensite influenced oxide nature/morphology. - Abstract: The oxidation behavior of grade 304L stainless steel (SS) subjected to different surface finishing (machining and grinding) operations was followed in situ by contact electric resistance (CER) and electrochemical impedance spectroscopy (EIS) measurements using controlled distance electrochemistry (CDE) technique in high purity water (conductivity −1) at 300 °C and 10 MPa in an autoclave connected to a recirculation loop system. The results highlight the distinct differences in the oxidation behavior of surface worked material as compared to solution annealed material in terms of specific resistivity and low frequency Warburg impedance. The resultant oxide layer was characterized for (a) elemental analyses by glow discharge optical emission spectroscopy (GDOES) and (b) morphology by scanning electron microscopy (SEM). Oxide layers with higher specific resistivity and chromium content were formed in case of machined and ground conditions. Presence of an additional ionic transport process has also been identified for the ground condition at the metal/oxide interface. These differences in electrochemical properties and distinct morphological features of the oxide layer as a result of surface working were attributed to the prevalence of heavily fragmented grain structure and presence of martensite.

  15. Antifouling Polymer Brushes Displaying Antithrombogenic Surface Properties.

    Science.gov (United States)

    de Los Santos Pereira, Andres; Sheikh, Sonia; Blaszykowski, Christophe; Pop-Georgievski, Ognen; Fedorov, Kiril; Thompson, Michael; Rodriguez-Emmenegger, Cesar

    2016-03-14

    The contact of blood with artificial materials generally leads to immediate protein adsorption (fouling), which mediates subsequent biological processes such as platelet adhesion and activation leading to thrombosis. Recent progress in the preparation of surfaces able to prevent protein fouling offers a potential avenue to mitigate this undesirable effect. In the present contribution, we have prepared several types of state-of-the-art antifouling polymer brushes on polycarbonate plastic substrate, and investigated their ability to prevent platelet adhesion and thrombus formation under dynamic flow conditions using human blood. Moreover, we compared the ability of such brushes-grafted on quartz via an adlayer analogous to that used on polycarbonate-to prevent protein adsorption from human blood plasma, assessed for the first time by means of an ultrahigh frequency acoustic wave sensor. Results show that the prevention of such a phenomenon constitutes one promising route toward enhanced resistance to thrombus formation, and suggest that antifouling polymer brushes could be of service in biomedical applications requiring extensive blood-material surface contact. PMID:26882214

  16. Mechanical properties and fracture behavior of single-layer phosphorene at finite temperatures

    Science.gov (United States)

    Sha, Zhen-Dong; Pei, Qing-Xiang; Ding, Zhiwei; Jiang, Jin-Wu; Zhang, Yong-Wei

    2015-10-01

    Phosphorene, a new two-dimensional (2D) material beyond graphene, has attracted great attention in recent years due to its superior physical and electrical properties. However, compared to graphene and other 2D materials, phosphorene has a relatively low Young’s modulus and fracture strength, which may limit its applications due to possible structure failures. For the mechanical reliability of future phosphorene-based nanodevices, it is necessary to have a deep understanding of the mechanical properties and fracture behaviors of phosphorene. Previous studies on the mechanical properties of phosphorene were based on first principles calculations at 0 K. In this work, we employ molecular dynamics simulations to explore the mechanical properties and fracture behaviors of phosphorene at finite temperatures. It is found that temperature has a significant effect on the mechanical properties of phosphorene. The fracture strength and strain reduce by more than 65% when the temperature increases from 0 K to 450 K. Moreover, the fracture strength and strain in the zigzag direction is more sensitive to the temperature rise than that in the armchair direction. More interestingly, the failure crack propagates preferably along the groove in the puckered structure when uniaxial tension is applied in the armchair direction. In contrast, when the uniaxial tension is applied in the zigzag direction, multiple cracks are observed with rough fracture surfaces. Our present work provides useful information about the mechanical properties and failure behaviors of phosphorene at finite temperatures.

  17. Surface coating affects behavior of metallic nanoparticles in a biological environment

    Science.gov (United States)

    Jurašin, Darija Domazet; Ćurlin, Marija; Capjak, Ivona; Crnković, Tea; Lovrić, Marija; Babič, Michal; Horák, Daniel; Gajović, Srećko

    2016-01-01

    Summary Silver (AgNPs) and maghemite, i.e., superparamagnetic iron oxide nanoparticles (SPIONs) are promising candidates for new medical applications, which implies the need for strict information regarding their physicochemical characteristics and behavior in a biological environment. The currently developed AgNPs and SPIONs encompass a myriad of sizes and surface coatings, which affect NPs properties and may improve their biocompatibility. This study is aimed to evaluate the effects of surface coating on colloidal stability and behavior of AgNPs and SPIONs in modelled biological environments using dynamic and electrophoretic light scattering techniques, as well as transmission electron microscopy to visualize the behavior of the NP. Three dispersion media were investigated: ultrapure water (UW), biological cell culture medium without addition of protein (BM), and BM supplemented with common serum protein (BMP). The obtained results showed that different coating agents on AgNPs and SPIONs produced different stabilities in the same biological media. The combination of negative charge and high adsorption strength of coating agents proved to be important for achieving good stability of metallic NPs in electrolyte-rich fluids. Most importantly, the presence of proteins provided colloidal stabilization to metallic NPs in biological fluids regardless of their chemical composition, surface structure and surface charge. In addition, an assessment of AgNP and SPION behavior in real biological fluids, rat whole blood (WhBl) and blood plasma (BlPl), revealed that the composition of a biological medium is crucial for the colloidal stability and type of metallic NP transformation. Our results highlight the importance of physicochemical characterization and stability evaluation of metallic NPs in a variety of biological systems including as many NP properties as possible. PMID:26977382

  18. Bio-inspired dual surface modification to improve tribological properties at small-scale

    Science.gov (United States)

    Singh, R. Arvind; Pham, Duc-Cuong; Kim, Jinseok; Yang, Sungwook; Yoon, Eui-Sung

    2009-02-01

    In miniaturized devices like micro/nano-electro-mechanical systems (MEMS/NEMS), the critical forces, namely adhesion and friction restrict the smooth operation of the elements that are in relative motion. MEMS/NEMS are traditionally made of silicon, whose tribological properties are not good. In this paper, we present an investigation on the approach of dual surface modification of silicon surfaces and their tribological properties at micro-scale. The dual surface modification is a combination of topographical and chemical modifications. As the topographical modification, micro-patterns with varying shapes of pillars and channels were fabricated on Si(1 0 0) wafer surfaces using photolithography method. Chemical modification included the coating of micro-patterns with diamond-like carbon (DLC) and Z-DOL (perfluoropolyether, PFPE) thin films. The surfaces with combined modification were evaluated for their micro-friction behavior in comparison with those of bare Si(1 0 0) flat surfaces and the topographically/chemically modified silicon surfaces. Results showed that the surfaces with dual modification exhibited superior tribological properties. These results indicate that a combination of topographical and chemical modification is very effective in enhancing tribological properties at small-scale. The combined surface treatments such as the ones investigated in the current work could be useful for tribological applications in small-scale devices such as MEMS/NEMS. The motivation for undertaking the dual modification approach comes from an earlier observation made on the significant influence of the surface characteristics of lotus leaf on its micro-friction behavior.

  19. 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.

  20. Surface and electrocatalytic properties of tungsten bronzes

    International Nuclear Information System (INIS)

    Tafel plots have been obtained for the oxygen reaction in acid solution on several alkali tungsten bronzes having different crystal structures. Platinum doped sodium tungsten bronze crystals were studied and the results compared with those of platinum free crystals of the same composition. In both cases sodium tungsten bronzes were found to be poor electrocatalysts for the cathodic reduction of oxygen. Similar results are reported for other alkali tungsten bronzes and for tungsten trioxide. Anodic treatment of the crystals affected the electrocatalytic activity of only the sodium tungsten bronze and the effect was a negative one. Cyclic voltammetry was employed to study the effects of the anodic treatment which created a sodium depletion layer on the sodium tungsten bronze surface. The existence and depth of the sodium depletion layer was determined by an Auger Electron Spectroscopy depth profile

  1. Surface and electrocatalytic properties of tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.F.; Shanks, H.R.

    1977-01-01

    Tafel plots have been obtained for the oxygen reaction in acid solution on several alkali tungsten bronzes having different crystal structures. Platinum doped sodium tungsten bronze crystals were studied and the results compared with those of platinum free crystals of the same composition. In both cases sodium tungsten bronzes were found to be poor electrocatalysts for the cathodic reduction of oxygen. Similar results are reported for other alkali tungsten bronzes and for tungsten trioxide. Anodic treatment of the crystals affected the electrocatalytic activity of only the sodium tungsten bronze and the effect was a negative one. Cyclic voltammetry was employed to study the effects of the anodic treatment which created a sodium depletion layer on the sodium tungsten bronze surface. The existence and depth of the sodium depletion layer was determined by an Auger Electron Spectroscopy depth profile.

  2. Studies on the Surface Properties of MCM-41

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    MCM-41 materials with a well-ordered long-range structure, a large pore size and a high surface area have been synthesized. Their surface properties including the number and the nature of the surface hydroxyl groups and surface hydrophobicity/hydrophilicity have been investigated by means of 29Si MAS NMR and FT-IR spectra and TPD of probe molecules. The results clearly show that the surface of MCM-41 has an abundance of acidic silanol groups, and that the hydrophobicity/hydrophilicity can be modified by the introduction of Al and transition metals Ti, Cr, Ni and Fe into it.

  3. Surface Chemical Properties of Colloids in Main Soils of China

    Institute of Scientific and Technical Information of China (English)

    MAYI-JIE; YUANCHAO-LIANG

    1991-01-01

    Surface chemical properties of soil colloids are the important factor affecting soil fertility and genesis.To provide scientific basis for soil genetic classification,promotion of soil fertility and reasonable fertilizqation,the specific surface area and electric charge of soil colloids in relation to clay minerals and organic matter are further discussed on the basis of the results obtained from the studies on surface chemical properties of soil colloids in five main soils of China.Results from the studies show that the effect of clay minerals and organic matter on the surface chemical properties of soil colloids is very complicated because the siloxane surface,hydrated oxide surface and organic matter surface do not exist separately,but they are always mixed together and influenced each other.The understanding of the relationship among clay minerals,organic matter and surface chemical properties of soil colloids depends upon further study of the relevant disciplines of soil science,especially the study on the mechanisms of organo-mineral complexes.

  4. Surface and mechanical properties of polypropylene/clay nanocomposite

    OpenAIRE

    Dibaei Asl Husein; Abdouss Majid; Torabi Angaji Mahmoud; Haji Aminoddin

    2013-01-01

    Huge consumption of polypropylene in the industries like automotive motivates academic and industrial R&Ds to find new and excellent approaches to improve the mechanical properties of this polymer, which has no degradation effect on other required performance properties like impact resistance, controlled crystallinity, toughness and shrinkage. Nowadays, nanoparticles play a key role in improving the mechanical and surface properties of polypropylene. In this study, three compositions of...

  5. Creep behavior and surface characterization of a laser surface nitrided Ti–6Al–4V alloy

    International Nuclear Information System (INIS)

    Laser surface nitriding of a Ti–6Al–4V alloy is studied with the aim of increasing creep resistance. A detailed characterization of the surface and cross section of the nitrided laser surface was carried out by optical/scanning electron microscopy and X-ray diffraction techniques. The microstructure of the surface-nitrided Ti–6Al–4V consists of TiN dendrites distributed in a martensitic titanium matrix. Finally, the mechanical properties in terms of microindentation hardness and creep resistance were evaluated. Constant load creep tests were conducted on a standard creep machine at different stress levels at 500 °C, 600 °C and 700 °C. Results indicated that the creep rates of the laser nitrided alloy were lower than those of the untreated material and the microhardness of the surface was improved to 1100 VHN compared with the 340 VHN of the substrate

  6. Creep behavior and surface characterization of a laser surface nitrided Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Adriano Gonçalves dos, E-mail: areis@ita.br [Instituto Tecnológico de Aeronáutica—ITA/DCTA, Pr. M. Eduardo Gomes, 50, São José dos Campos—SP 12228-900 (Brazil); Reis, Danieli Aparecida Pereira [Universidade Federal de São Paulo—UNIFESP, R. Talim, 330, São José dos Campos—SP 12231-280 (Brazil); Moura Neto, Carlos de [Instituto Tecnológico de Aeronáutica—ITA/DCTA, Pr. M. Eduardo Gomes, 50, São José dos Campos—SP 12228-900 (Brazil); Barboza, Miguel Justino Ribeiro [Escola de Engenharia de Lorena—EEL/DEMAR/USP, Polo Urbo-Industrial Gleba AI-6 Caixa Postal 116, Lorena–SP 12600-970 (Brazil); Oñoro, Javier [Universidad Politécnica de Madrid—UPM, Plaza Cardenal Cisneros, 3, Madrid 28040 (Spain)

    2013-08-10

    Laser surface nitriding of a Ti–6Al–4V alloy is studied with the aim of increasing creep resistance. A detailed characterization of the surface and cross section of the nitrided laser surface was carried out by optical/scanning electron microscopy and X-ray diffraction techniques. The microstructure of the surface-nitrided Ti–6Al–4V consists of TiN dendrites distributed in a martensitic titanium matrix. Finally, the mechanical properties in terms of microindentation hardness and creep resistance were evaluated. Constant load creep tests were conducted on a standard creep machine at different stress levels at 500 °C, 600 °C and 700 °C. Results indicated that the creep rates of the laser nitrided alloy were lower than those of the untreated material and the microhardness of the surface was improved to 1100 VHN compared with the 340 VHN of the substrate.

  7. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

    OpenAIRE

    Alfred Tcherbi-Narteh; Mahesh V. Hosur; Eldon Triggs; Shaik Jelaani

    2013-01-01

    Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the ep...

  8. Immersed superhydrophobic surfaces: Gas exchange, slip and drag reduction properties

    OpenAIRE

    McHale, Glen; Newton, Michael; Shirtcliffe, Neil

    2010-01-01

    Superhydrophobic surfaces combine high aspect ratio micro- or nano-topography and hydrophobic surface chemistry to create super water-repellent surfaces. Most studies consider their effect on droplets, which ball-up and roll-off. However, their properties are not restricted to modification of the behaviour of droplets, but potentially influence any process occurring at the solid-liquid interface. Here, we highlight three recent developments focused on the theme of immersed superhydrophobic su...

  9. Surface properties and microporosity of polyhydroxybutyrate under scanning electron microscopy

    International Nuclear Information System (INIS)

    This study was designed to investigate the surface properties especially surface porosity of polyhydroxybutyrate (PHB) using scanning electron microscopy. PHB granules were sprinkled on the double-sided sticky tape attached on a SEM aluminium stub and sputtered with gold (10nm thickness) in a Polaron SC515 Coater, following which the samples were placed into the SEM specimen chamber for viewing and recording. Scanning electron micrographs with different magnification of PHB surface revealed multiple pores with different sizes. (Author)

  10. Effect of surface property on electrochemical kinetics in high temperature water

    International Nuclear Information System (INIS)

    The effect of various surface properties on the polarization behavior of hydrogen (H2) oxidation, oxygen (O2) reduction, and electrochemical corrosion potential (ECP) on 304 stainless steel (SS) in high temperature, high purity water was studied. It is evident that the presence of noble metals on the oxide surface dramatically improves the hydrogen oxidation kinetics and thus enhances the catalytic recombination efficiency of H2 to O2 to form H2O. The enhancement in the catalytic nature on 304 SS surface doped with noble metals results in a thermodynamically lowest electrochemical corrosion potential (ECP) value (she in 288 C water without addition of hydrogen (H2). (authors)

  11. Investigation of surface properties of high temperature nitrided titanium alloys

    OpenAIRE

    Koyuncu, E.; F. Kahraman; Ö. Karadeniz

    2009-01-01

    Purpose: The purpose of paper is to investigate surface properties of high temperature nitrided titanium alloys.Design/methodology/approach: In this study, surface modification of Ti6Al4V titanium alloy was made at various temperatures by plasma nitriding process. Plasma nitriding treatment was performed in 80% N2-20% H2 gas mixture, for treatment times of 2-15 h at the temperatures of 700-1000°C. Surface properties of plasma nitrided Ti6Al4V alloy were examined by metallographic inspection, ...

  12. Cloud microphysics and surface properties in climate

    Energy Technology Data Exchange (ETDEWEB)

    Stamnes, K. [Univ. of Alaska, Fairbanks, AK (United States)

    1995-09-01

    Cloud optical thickness is determined from ground-based measurements of broadband incoming solar irradiance using a radiation model in which the cloud optical depth is adjusted until computed irradiance agrees with the measured value. From spectral measurements it would be feasible to determine both optical thickness and mean drop size, which apart from cloud structure and morphology, are the most important climatic parameters of clouds. A radiative convective model is used to study the sensitivity of climate to cloud liquid water amount and cloud drop size. This is illustrated in Figure 21.1 which shows that for medium thick clouds a 10 % increase in drop size yields a surface warming of 1.5{degrees}C, which is the same as that due to a doubling of carbon dioxide. For thick clouds, a 5% decrease in drop size is sufficient to offset the warming due to doubling of carbon dioxide. A radiative transfer model for the coupled atmosphere/sea ice/ocean system is used to study the partitioning of radiative energy between the three strata, and the potential for testing such a model in terms of planned experiments in the Arctic is discussed.

  13. Fermi surface behavior in the ABJM M2-brane theory

    Science.gov (United States)

    DeWolfe, Oliver; Henriksson, Oscar; Rosen, Christopher

    2015-06-01

    We calculate fermionic Green's functions for states of the three-dimensional Aharony-Bergman-Jafferis-Maldacena M2-brane theory at large N using the gauge-gravity correspondence. We embed extremal black brane solutions in four-dimensional maximally supersymmetric gauged supergravity, obtain the linearized Dirac equations for each spin-1 /2 mode that cannot mix with a gravitino, and solve these equations with infalling boundary conditions to calculate retarded Green's functions. For generic values of the chemical potentials, we find Fermi surfaces with universally non-Fermi liquid behavior, matching the situation for four-dimensional N =4 super-Yang-Mills. Fermi surface singularities appear and disappear discontinuously at the point where all chemical potentials are equal, reminiscent of a quantum critical point. One limit of parameter space has zero entropy at zero temperature, and fermionic fluctuations are perfectly stable inside an energy region around the Fermi surface. An ambiguity in the quantization of the fermions is resolved by supersymmetry.

  14. Chitosan/titanium dioxide nanocomposite coatings: Rheological behavior and surface application to cellulosic paper.

    Science.gov (United States)

    Tang, Yanjun; Hu, Xiulan; Zhang, Xinqi; Guo, Daliang; Zhang, Junhua; Kong, Fangong

    2016-10-20

    Incorporation of nanofillers into a polymeric matrix has received much attention as a route to reinforced polymer nanocomposites. In the present work, an environmentally friendly chitosan (CTS)/titanium dioxide (TiO2) nanocomposite coating was designed/prepared and subsequently employed for imparting antibacterium and improved mechanical properties to cellulosic paper via surface coating. Effect of TiO2 nanoparticle loadings on the rheological behavior of nanocomposite coatings was investigated. Surface application of CTS/TiO2 nanocomposite coatings to cellulosic paper was performed, and the antibacterial activity and mechanical properties of surface-coated cellulosic paper were examined. Results showed that the increased TiO2 nanoparticle loadings decreased the viscosity and dynamic viscoelasticity of the as-prepared coatings, and improved the antibacterial activity and mechanical properties of surface-coated cellulosic paper. The optimum loading of TiO2 nanoparticles was identified at 10%. This work suggested that CTS/TiO2 nanocomposite coatings may have the potential to be used as a promising antibacterial protective coating for paper packaging. PMID:27474622

  15. A new model for thermodynamic analysis on wetting behavior of superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Hongyun [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education and Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105 (China); Li Wen, E-mail: liwen@xtu.edu.cn [Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education and Faculty of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan 411105 (China); Fang Guoping [Department of mechanical Engineering, University of Alberta, Edmonton, AB, T6G 2G8 (Canada)

    2012-01-15

    Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces.

  16. A new model for thermodynamic analysis on wetting behavior of superhydrophobic surfaces

    International Nuclear Information System (INIS)

    Superhydrophobic surfaces have shown inspiring applications in microfluidics, and self-cleaning coatings owing to water-repellent and low-friction properties. However, thermodynamic mechanism responsible for contact angle hysteresis (CAH) and free energy barrier (FEB) have not been understood completely yet. In this work, we propose an intuitional 3-dimension (3D) droplet model along with a reasonable thermodynamic approach to gain a thorough insight into the physical nature of CAH. Based on this model, the relationships between radius of three-phase contact line, change in surface free energy (CFE), average or local FEB and contact angle (CA) are established. Moreover, a thorough theoretical consideration is given to explain the experimental phenomena related to the superhydrophobic behavior. The present study can therefore provide some guidances for the practical fabrications of the superhydrophobic surfaces.

  17. Effect of surface treatments on the surface morphology, corrosion property, and antibacterial property of Ti-10Cu sintered alloy.

    Science.gov (United States)

    Zhang, Erlin; Liu, Cong

    2015-08-01

    Ti-10Cu sintered alloy has shown strong antibacterial properties against S. aureus and E. coli and good cell biocompatibility in vitro and in vivo, displaying potential application as an implant material. Surface treatments are always applied to implants to improve the surface biocompatibility. In this paper, several typically used surface treatments, including sandblasting (SB), sandblasted and large-grits acid etching (SLA), and alkaline heat treatment (AH) were chosen to modify the Ti-10Cu. A cp-Ti (commercially pure titanium) sample was used as control sample. The effect of surface treatments on the corrosion properties and antibacterial properties of the Ti-10Cu sintered alloy was investigated. After SB and SLA treatments, a rough surface with a TiO2 layer was formed on the surface, which reduced the corrosion resistance and enhanced the Ti and Cu ion release. After AH treatment, a smooth but microporous surface with a TiO2/titanate layer was formed, which improved slightly the corrosion resistance. However, the Cu ion and Ti ion release from the Ti-10Cu sample was promoted by AH treatment due to the fact that more Ti2Cu phases were exposed on the AH-treated Ti-10Cu sample. It was demonstrated that the Ti-10Cu samples after surface treatments still exhibited good antibacterial properties against S. aureus, which indicated that the surface treatment did not reduce the antibacterial activity. The control mechanism was thought to be related to the high Cu ion release even after surface treatments. It was expected that the surface treatments provided Ti-10Cu sintered alloy with good surface bioactivity without reduction in antibacterial activity. PMID:26201969

  18. Corrosion Behavior of Surface-treated Ferritic/Martensitic Steel in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, JeongHyeon; Lee, Jung Ki; Kim, Ji Hyun [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Shin, Sang Hun [KAERI, Daejeon (Korea, Republic of)

    2015-10-15

    Their compatibility with sodium is one of issues especially dissolution, chemical reaction, and carbon transfer with impurities, which degraded the mechanical properties. The compatibility of cladding and structural materials with sodium has to be carefully investigated, as sodium could promote corrosion of cladding and structural materials in two ways. One is produced by the dissolution of alloy constituents into the sodium, and the other is produced through a chemical reaction with impurities (especially oxygen and carbon) in the sodium environment. Gr.92 is known as compatible in sodium environment because this steel possesses excellent properties. For instance, Gr.92 has high creep and tensile strength, low thermal expansion coefficient. In the Ultra-long Cycle Fast Reactor (UCFR) which is developed in UNIST, however, cladding is exposed long-term in high temperature liquid sodium environment. So, it is very important to investigate the corrosion-related behavior such as surface corrosion rate, carburization, decarburization and mechanical properties for its operation time. In this study, as-received and surface-treated Gr.92 specimen in the oxygen-saturated liquid sodium were examined at high temperature for 300h. The impedance results reveal the information for the corrosion behavior in liquid sodium. Also, microstructure results reveal the information for the maintenance of coating and role of coating.

  19. Properties of Surface Cyclic Oligomers Present on Polyester Fiber

    Institute of Scientific and Technical Information of China (English)

    郑敏; 宋心远

    2003-01-01

    The effects of different treatments, such as dry heat,wet heat, solvent vapor and ultrasonic, on properties of the cyclic oligomers on the surface of polyester fiber are studied. The components of surface oligomers are analyzed through Thin-Layer Chromatograph. The result shows that: all of the treatments, especially solvent vapor treatment, can significantly increase the content of surface cyclic oligomers. The content of cyclic trimer is increased more considerably than other oligomers. Moreover, the morphology and the distribution of surface cyclic oligomers are also different from different treatments: Dry heat and wet heat cause larger polygonal solids distributed evenly on the surface of fiber; solvent vapor makes fiber surface exhibit irregular rodlike crystal shapes randomly; ultrasonic treatment induces some obscure and smaller deposits on the surface of fiber.

  20. Role of surface vibrational properties on cooperative phenomena in spin-crossover nanomaterials

    Science.gov (United States)

    Mikolasek, Mirko; Félix, Gautier; Molnár, Gábor; Terki, Férial; Nicolazzi, William; Bousseksou, Azzedine

    2014-08-01

    The influence of surface/interface on the lattice dynamics of spin crossover nanoparticles has been investigated by a spring-ball model solved by Monte Carlo methods. The bond cohesion energy of the model has been extracted from Mössbauer spectroscopy measurements performed on the model compound Ni3[Fe(CN)6]. We show that the coupling between bulk and surface vibrational properties, which drastically affects the mechanical properties of the whole particle below a characteristic size, has a major impact on the phase stability of the particles. In the case of free surfaces, the Debye temperature decreases with the size and the first-order nature of the spin transition disappears. On the other hand, a hardening of the surface bonds leads to increasing particle stiffness with the size reduction. In this case, a persistence of the hysteretic behavior in the spin transition curve is also predicted in good agreement with previous theoretical and experimental results.

  1. Friction behavior of a microstructured polymer surface inspired by snake skin

    Science.gov (United States)

    Heepe, Lars; Gorb, Stanislav N

    2014-01-01

    Summary The aim of this study was to understand the influence of microstructures found on ventral scales of the biological model, Lampropeltis getula californiae, the California King Snake, on the friction behavior. For this purpose, we compared snake-inspired anisotropic microstructured surfaces to other microstructured surfaces with isotropic and anisotropic geometry. To exclude that the friction measurements were influenced by physico-chemical variations, all friction measurements were performed on the same epoxy polymer. For frictional measurements a microtribometer was used. Original data were processed by fast Fourier transformation (FFT) with a zero frequency related to the average friction and other peaks resulting from periodic stick-slip behavior. The data showed that the specific ventral surface ornamentation of snakes does not only reduce the frictional coefficient and generate anisotropic frictional properties, but also reduces stick-slip vibrations during sliding, which might be an adaptation to reduce wear. Based on this extensive comparative study of different microstructured polymer samples, it was experimentally demonstrated that the friction-induced stick-slip behavior does not solely depend on the frictional coefficient of the contact pair. PMID:24611129

  2. Functional properties of laser modified surface of tool steel

    OpenAIRE

    M. Bonek; L.A. Dobrzański

    2006-01-01

    Purpose: Investigations include alloying the surface of X40CrMoV5-1 hot-work tool steel with tungsten carbide using a high power diode laser (HPDL).Design/methodology/approach: The structural mechanism of surface layer development was determined and the effect of alloying parameters, gas protection method, and thickness of paste layer applied onto the steel surface on structure refinement and influence of these factors on the mechanical properties of surface layer was studied.Findings: The fi...

  3. Manipulation and behavior modeling of one-dimensional nanomaterials on a structured surface

    International Nuclear Information System (INIS)

    Different diameters of multiwall carbon nanotubes (CNTs) are manipulated by a cantilever tip of an atomic force microscope (AFM) to investigate the motion properties of one-dimensional nanomaterials on a structured surface. To describe the mechanical behaviors of this kind of samples, two mechanical models based on continuum mechanics are proposed. Through foreseeable manipulation procedures, we are able to position the tubes onto pre-etched micro trenches, and then measure their Young's moduli by the three-point bending method. Both string-like and beam-like deformation forms are observed on the tested samples. Additionally, we present a reparable 'collapse' phenomenon of the nanotube bridges.

  4. Wettability and antifouling behavior on the surfaces of superhydrophilic polymer brushes.

    Science.gov (United States)

    Kobayashi, Motoyasu; Terayama, Yuki; Yamaguchi, Hiroki; Terada, Masami; Murakami, Daiki; Ishihara, Kazuhiko; Takahara, Atsushi

    2012-05-01

    The surface wettabilities of polymer brushes with hydrophobic and hydrophilic functional groups were discussed on the basis of conventional static and dynamic contact angle measurements of water and hexadecane in air and captive bubble measurements in water. Various types of high-density polymer brushes with nonionic and ionic functional groups were prepared on a silicon wafer by surface-initiated atom-transfer radical polymerization. The surface free energies of the brushes were estimated by Owens-Wendt equation using the contact angles of various probe liquids with different polarities. The decrease in the water contact angle corresponded to the polarity of fluoroalkyl, hydroxy, ethylene oxide, amino, carboxylic acid, ammonium salt, sulfonate, carboxybetaine, sulfobetaine, and phosphobetaine functional groups. The poly(2-perfluorooctylethyl acrylate) brush had a low surface free energy of approximately 8.7 mN/m, but the polyelectrolyte brushes revealed much higher surface free energies of 70-74 mN/m, close to the value for water. Polyelectrolyte brushes repelled both air bubbles and hexadecane in water. Even when the silicone oil was spread on the polyelectrolyte brush surfaces in air, once they were immersed in water, the oil quickly rolled up and detached from the brush surface. The oil detachment behavior observed on the superhydrophilic polyelectrolyte brush in water was explained by the low adhesion force between the brush and the oil, which could contribute to its excellent antifouling and self-cleaning properties. PMID:22500465

  5. Lipophilic phytosterol derivatives: synthesis, thermal property and nanoemulsion behavior

    DEFF Research Database (Denmark)

    Panpipat, Worawan; Xu, Xuebing; Guo, Zheng

    phytosterols into enzyme-liable lipophilic derivatives, such as fatty acid esters was one of the possible strategies. Differences in molecular structures of modified phytosterols may result in the differences in their thermal and micelling behaviors. Therefore, the objectives of this study were to improve the...... productive yield of a series of -sitosteryl fatty acid esters (C2-C18) and to investigate the thermal property and nano-emulsion behaviors of those compounds. This work reported a novel approach to synthesize phytosterol (-sitosterol as a model) fatty acid ester by employing Candida antarctica lipase A...... of -sitosterol fatty acid esters was governed by the carbon chain length of fatty acid incorporated. The nano-emulsions of a series of -sitosteryl fatty acid esters were prepared by probe-sonication method. The particle size distributions, zeta potentials and TEM images of those emulsions were...

  6. Effective modification of particle surface properties using ultrasonic water mist

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki;

    2009-01-01

    properties. It was found that rapid exposition of pharmaceutical materials by water mist resulted in the improvement of powder technical properties. The evident changes in flowability of coarser lactose were obviously due to smoothing of particle surface and decreasing in the level of fines with very slight...... the studied materials. The proposed water mist treatment technique appears to be a robust, rapid, and promising tool for the improvement of the technological properties of pharmaceutical powders.......The goal of the present study was to design a new technique to modify particle surface properties and, through that, to improve flowability of poorly flowing drug thiamine hydrochloride and pharmaceutical sugar lactose monohydrate of two different grades. The powdered particles were supplied by a...

  7. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    L(U) Yongjun; WEI Bingbo

    2006-01-01

    Molecular dynamics simulations were performed to study the surface properties of water in a temperature range from 228 to 293 K by using the extended simple point charge (SPC/E) and four-site TIP4P potentials. The calculated surface tension increases with the decrease of temperature, and moreover the slopes of the surface tension-temperature curves show a weak rise below 273 K, whereas no obvious anomalies appear near 228 K, which accords with the previous experiments. Compared with the measured values, the SPC/E potential shows a good agreement, and the TIP4P potential scription of the surface structure of supercooled water for the SPC/E. When simulating the orientational distributions of water molecules near the surface, the SPC/E potential produces higher ordering and larger surface potentials than the TIP4P potential.

  8. Surface Plasmon's Dispersion Properties of Porous Gold Films.

    Science.gov (United States)

    Stetsenko, M O; Maksimenko, L S; Rudenko, S P; Krishchenko, I M; Korchovyi, A A; Kryvyi, S B; Kaganovich, E B; Serdega, B K

    2016-12-01

    Nanostructure porous films with arrays of gold nanoparticles (Au NPs) have been produced by pulsed laser deposition. Dispersion properties of surface plasmons have been studied by the modulation-polarization spectroscopy technique. The dispersion relations for radiative modes and two types of non-radiative modes of localized and propagating surface plasmons were obtained. The branches of propagating modes were characterized by negative group velocity caused by spatial dispersion of dielectric function. The propagating modes are caused by dipole-dipole interactions between adjacent Au NPs. The frequencies and relaxation parameters of surface plasmon resonances and the plasma frequencies for Αu NPs were obtained. The relation between the surface plasmon's properties and formation conditions of films with arrays of Αu NPs is discussed. PMID:26925864

  9. Anomalous hysteresis properties of iron films deposited on liquid surfaces

    Science.gov (United States)

    Ye, Quan-Lin; Feng, Chun-Mu; Xu, Xiao-Jun; Jin, Jin-Sheng; Xia, A.-Gen; Ye, Gao-Xiang

    2005-07-01

    A nearly free sustained iron film system, deposited on silicone oil surfaces by vapor-phase deposition method, has been fabricated and its crystal structure as well as magnetic properties has been studied. Both the temperature-dependent coercivity Hc(T) and exchange anisotropy field HE(T) of the iron films possess a maximum peak around the critical temperature Tcrit=10-15 and 4K, respectively. Our experimental results show that the anomalous hysteresis properties mainly result from the oxide surfaces of the films with spin-glass-like phase below freezing temperature Tf=30-50K.

  10. Surface delta interaction and properties of medium mass nuclei

    International Nuclear Information System (INIS)

    The idea of Surface Delta Interaction (SDI) is that because of Pauli principle, the interaction between nucleons is peaked near the surface of the nucleus. The delta potential is short ranged like free NN interaction. It has some interesting properties which makes it a quite 'realistic' interaction, to use. SDI gives matrix elements which are quite close to empirical matrix elements found from shell model studies. Also this interaction reproduces deformation properties quite well in complex nuclei. Comparison of SDI matrix elements with two modern interactions, namely, JUN45 and G-f5pg9 interaction has been made and report some applications to finite nuclei

  11. The surface properties of biopolymer-coated fruit: A review

    Directory of Open Access Journals (Sweden)

    Diana Cristina Moncayo Martinez

    2012-10-01

    Full Text Available Environmental conservation concerns have led to research and development regarding biodegradable materials from biopolymers, leading to new formulations for edible films and coatings for preserving the quality of fresh fruit and vegetables. Determining fruit skin surface properties for a given coating solution has led to predicting coating efficiency. Wetting was studied by considering spreading, adhesion and cohesion and measuring the contact angle, thus optimising the coating formulation in terms of biopolymer, plasticiser, surfactant, antimicrobial and antioxidant concentration. This work reviews the equations for determining fruit surface properties by using polar and dispersive interaction calculations and by determining the contact angle.

  12. Division of Icy Bodies into Groups Based on Surface Properties

    Science.gov (United States)

    Schaefer, Bradley E.; Rabinowitz, D. L.; Tourtellottte, S. W.

    2008-09-01

    We propose the division of the icy bodies in the outer Solar System into five groups based on their surface properties. This division can be equivalently made by three definitions involving: size/orbit/color; measured surface properties; the physical mechanisms that reprocess the surfaces. Our first group is the Small/Red bodies (including the red Centaurs, Kuiper Belt Objects, and Scattered Disk Objects) which are 1.5 mag. These surfaces all have albedo history leaving only their original rocky material to cover the surface. Our third group is the Intermediate bodies (Quaoar, Orcus, and Charon) with diameters 800-1400 km. Their surfaces have lost some of the volatile ices (methane and nitrogen in particular) to Jeans escape, while the remaining ices contain ammonia and crystalline water ice with some cryovolcanism. Our fourth group is the Large bodies (Pluto, Eris, Sedna, Triton, and 2005 FY9) with diameters >1400; km. These bodies are large enough to support active cryovolcanism plus seasonal frost formation/sublimation and are large enough so that the methane and nitrogen ices dominate because they have not been lost to Jeans escape. Our fifth group is the Collisional bodies (including the 2003 EL61 collisional family) which all have similar orbits. Their surfaces all have very neutral colors, low opposition surges, and relatively high albedos, because the volatile ices were all lost during the collision leaving a young surface with only water ice.

  13. Effects of short-time heat treatment and subsequent chemical surface treatment on the mechanical properties, low-cycle fatigue behavior and corrosion resistance of a Ni-Ti (50.9 at.% Ni) biomedical alloy wire used for the manufacture of stents

    International Nuclear Information System (INIS)

    Research highlights: → Effect of short-time heat treatments on functional properties of a NiTi alloy. → Negative effect of heat treatments on corrosion resistance. → Positive effect of heat treatments on fatigue life. → Positive influence of chemical treatment on both fatigue and corrosion resistance. - Abstract: Cold-drawn and straight-annealed NiTi wires (50.9% Ni) with a tensile strength of 1650 MPa were subjected to heat treatments at 450, 510 and 600 deg. C for 10 min in air to simulate the shape-setting process in the manufacture of stents. Afterwards, the wires were chemically etched in acidic baths containing HF, HNO3 and H2O, followed by boiling in water. Variations in the internal structure, surface state and chemistry and transformation behavior of the wires due to these treatments were examined in detail by scanning and transmission electron microscopy, energy dispersion spectrometry, glow discharge spectrometry, X-ray photoelectron spectroscopy and differential scanning calorimetry. Mechanical properties were determined by tensile tests, and low-cycle fatigue behavior was measured by bend-type cyclic loading tests. Corrosion behavior was assessed by immersion tests and potentiodynamic measurements. A high tensile strength of the wire was shown to be attributable to a very fine-grained structure and work hardening. Heat treatment at 450-510 deg. C/10 min did not significantly affect the tensile strength of the wire. At 600 deg. C/10 min, the strength decreased by about 600 MPa due to recrystallization. The transformation temperatures first slightly increased after heat treatment at 450 deg. C and then reduced after treatments at higher temperatures due to changes in the composition of the B2 phase. The fatigue life was observed to prolong with both heat treatment and chemical etching. In contrast, the corrosion resistance worsened with heat treatment, but it improved significantly upon chemical etching. The observed behaviors are discussed in

  14. Cesium Eluate Evaporation Solubility and Physical Property Behavior

    International Nuclear Information System (INIS)

    The baseline flowsheet for low activity waste (LAW) in the Hanford River Protection Project (RPP) Waste Treatment Plant (WTP) includes pretreatment of supernatant by removing cesium using ion exchange. When the ion exchange column is loaded, the cesium will be eluted with a 0.5M nitric acid (HNO3) solution to allow the column to be conditioned for re-use. The cesium eluate solution will then be concentrated in a vacuum evaporator to minimize storage volume and recycle HNO3. To prevent the formation of solids during storage of the evaporator bottoms, criteria have been set for limiting the concentration of the evaporator product to 80 percent of saturation at 25 degrees C. A fundamental element of predicting evaporator product solubility is to collect data that can be used to estimate key operating parameters. The data must be able to predict evaporator behavior for a range of eluate concentrations that are evaporated to the point of precipitation. Parameters that were selected for modeling include solubility, density, viscosity, thermal conductivity, and heat capacity. Of central importance is identifying the effect of varying feed components on overall solubility. The point of solubility defines the upper limit for eluate evaporation operations and liquid storage. The solubility point also defines those chemical compounds that have the greatest effects on physical properties. Third, solubility behavior identifies intermediate points where physical property data should be measured for the database. Physical property data (density, viscosity, thermal conductivity, and heat capacity) may be an integral part of tracking evaporator operations as they progress toward their end point. Once the data have been collected, statistical design software can develop mathematical equations that estimate solubility and other physical properties

  15. Derivatization, characterization, and tribological behavior of an amine-terminated polymer surface

    International Nuclear Information System (INIS)

    The derivatization, characterization, and micro-tribological behavior of an amine-terminated polymer surface were investigated. Thus, the heptafluorobutyric anhydride (HFBA) derivatized film was characterized by means of contact-angle measurement and X-ray photoelectron spectroscopy (XPS). It was found that the HFBA-derivatized film was generated on the PEI surface in the presence of a chemical amide bond. The tribological properties were characterized as well. The polymer PEI film had relative high adhesion, friction, and poor anti-wear ability, while the HFBA-derivatized polymer film possessed a very low adhesive force of only about 5.5 nN (a pyramidal Si3N4 tip with radius of curvature about 50 nm was used to measure the adhesion), which was more than an order of magnitude lower than that of the silicon substrate surface. Besides, the HFBA-derivatized film registered good friction-reducing ability and thermal stability. Thus, a good alternative method was presented to improve the tribological properties of polymer film by chemisorbing molecules with low surface energy. This makes it feasible for the derivatized polymer film to find promising application in resolving the tribological problems of micro-electromechanical systems (MEMS)

  16. Fracture behavior of short circumferentially surface-cracked pipe

    Energy Technology Data Exchange (ETDEWEB)

    Krishnaswamy, P.; Scott, P.; Mohan, R. [Battelle, Columbus, OH (United States)] [and others

    1995-11-01

    This topical report summarizes the work performed for the Nuclear Regulatory Comniission`s (NRC) research program entitled ``Short Cracks in Piping and Piping Welds`` that specifically focuses on pipes with short, circumferential surface cracks. The following details are provided in this report: (i) material property deteminations, (ii) pipe fracture experiments, (iii) development, modification and validation of fracture analysis methods, and (iv) impact of this work on the ASME Section XI Flaw Evaluation Procedures. The material properties developed and used in the analysis of the experiments are included in this report and have been implemented into the NRC`s PIFRAC database. Six full-scale pipe experiments were conducted during this program. The analyses methods reported here fall into three categories (i) limit-load approaches, (ii) design criteria, and (iii) elastic-plastic fracture methods. These methods were evaluated by comparing the analytical predictions with experimental data. The results, using 44 pipe experiments from this and other programs, showed that the SC.TNP1 and DPZP analyses were the most accurate in predicting maximum load. New Z-factors were developed using these methods. These are being considered for updating the ASME Section XI criteria.

  17. Fracture behavior of short circumferentially surface-cracked pipe

    International Nuclear Information System (INIS)

    This topical report summarizes the work performed for the Nuclear Regulatory Comniission's (NRC) research program entitled ''Short Cracks in Piping and Piping Welds'' that specifically focuses on pipes with short, circumferential surface cracks. The following details are provided in this report: (i) material property deteminations, (ii) pipe fracture experiments, (iii) development, modification and validation of fracture analysis methods, and (iv) impact of this work on the ASME Section XI Flaw Evaluation Procedures. The material properties developed and used in the analysis of the experiments are included in this report and have been implemented into the NRC's PIFRAC database. Six full-scale pipe experiments were conducted during this program. The analyses methods reported here fall into three categories (i) limit-load approaches, (ii) design criteria, and (iii) elastic-plastic fracture methods. These methods were evaluated by comparing the analytical predictions with experimental data. The results, using 44 pipe experiments from this and other programs, showed that the SC.TNP1 and DPZP analyses were the most accurate in predicting maximum load. New Z-factors were developed using these methods. These are being considered for updating the ASME Section XI criteria

  18. Effect of Sanding on Surface Properties of Medium Density Fiberboard

    OpenAIRE

    Nadir Ayrilmis, Zeki Candan, Turgay Akbulut, Ozgur Balkiz

    2010-01-01

    The objective of this research was to investigate the effects of sanding on the surface properties of the medium density fiberboard (MDF) panels made from Rhododendron ponticum L. wood. The MDF panels were sanded with different sizes of the sand paper grit: 60-, 60+80- or 60+80+120-grit. Surface absorption and surface roughness of the MDF panels were determined based on EN 382-1 standard and ISO 4287 by using a fi ne stylus profi lometer, respectively. Sessile water drop technique was used to...

  19. Enhancement of surface properties for coal beneficiation. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Chander, S.; Aplan, F.F.

    1992-01-30

    This report will focus on means of pyrite removal from coal using surface-based coal cleaning technologies. The major subjects being addressed in this study are the natural and modulated surface properties of coal and pyrite and how they may best be utilized to facilitate their separation using advanced surface-based coal cleaning technology. Emphasis is based on modified flotation and oil agglomerative processes and the basic principles involved. The four areas being addressed are: (1) Collectorless flotation of pyrite; (2) Modulation of pyrite and coal hydrophobicity; (3) Emulsion processes and principles; (4) Evaluation of coal hydrophobicity.

  20. Properties of single organic molecules on crystal surfaces

    CERN Document Server

    Grutter, Peter; Rosei, Federico

    2006-01-01

    Within nanoscience, an emerging discipline is the study of the physics and chemistry of single molecules. Molecules may be considered as the ultimate building blocks, and are therefore interesting for the development of molecular devices and for surface functionalization. Thus, it is interesting to study their properties when adsorbed on a suitable substrate such as a solid or crystal surface, and also for their potential applications in nano- or molecular-electronics and nanosensing. Investigations have been made possible by the advent of high resolution surface imaging and characterization t

  1. Impact of Foliage Surface Properties on Vegetation Reflection and Absorption

    Science.gov (United States)

    Yang, B.; Knyazikhin, Y.; Yan, L.; Zhao, Y.; Jiao, J.

    2013-12-01

    Optical properties of phytoelements and their distribution in the canopy space (i.e., canopy structure) are among key factors that determine light environment in vegetation canopies, which in turn drives various physiological and physical processes required for the functioning of plants. Canopy radiative response is the source of information about ecosystem properties from remote sensing. Understanding of how radiation interacts with foliage and traverses in the 3D vegetation canopy is essential to both modeling and remote sensing communities. Radiation scattered by a leaf includes information from two dissimilar sources - the leaf surface and leaf interior. The first component of scattered radiation emanates from light reflected at the air-cuticle interface. This portion of reflected radiation does not interact with biochemical constituents inside the leaf and depends on the properties of the leaf surface. The leaf cuticle acts as a "barrier" for photons to enter the mesophyll and be absorbed; thus, tending to increase the leaf scattering. The second component mainly results from radiation interactions within the leaf-interior. The canopy radiation regime is sensitive to canopy structure, leaf surface properties and leaf biochemical constituents. Impact of leaf surface properties on canopy reflection and absorption is poorly understood. Radiation scattered at the surface of leaves is partly polarized. Fresnel reflection is the principal cause of light polarization. Polarization measurements provide a means to assess the impact of leaf surface properties on canopy radiation regime. We measured Bidirectional Reflectance Factor (BRF) in the principal plane and its polarized portion of needles and shoots of two coniferous species in the 400 to 1000 nm spectral interval. The needle and shoot BRF spectra were decomposed into polarized (PBRF) and diffuse (DBRF) components: BRF=PBRF+DBRF. Our analyses indicate: 1) PBRF in forward directions can account for up to 70% of

  2. A Method to Simulate the Observed Surface Properties of Proton Irradiated Silicon Strip Sensors

    CERN Document Server

    Peltola, Timo; Dalal, Ranjeet; Eber, Robert; Eichhorn, Thomas; Lalwani, Kavita; Messineo, Alberto; Printz, Martin; Ranjan, Kirti

    2015-01-01

    During the scheduled high luminosity upgrade of LHC, the world's largest particle physics accelerator at CERN, the position sensitive silicon detectors installed in the vertex and tracking part of the CMS experiment will face more intense radiation environment than the present system was designed for. To upgrade the tracker to required performance level, extensive measurements and simulations studies have already been carried out. A defect model of Synopsys Sentaurus TCAD simulation package for the bulk properties of proton irradiated devices has been producing simulations closely matching with measurements of silicon strip detectors. However, the model does not provide expected behavior due to the fluence increased surface damage. The solution requires an approach that does not affect the accurate bulk properties produced by the proton model, but only adds to it the required radiation induced properties close to the surface. These include the observed position dependency of the strip detector's charge collec...

  3. Irradiation effects on the mechanical and thermal properties and surface tension of plasticised PVC

    International Nuclear Information System (INIS)

    Irradiation effects on the mechanical and thermal properties and surface tension of plasticised PVC. The mechanical and thermal behavior of 1 mm thick sheets of plasticised PVC after gamma irradiation at doses of 10 and 70 kGy was studied and compared to untreated PVC. The use of gamma irradiation treatment as plasticised PVC induces better mechanical properties, good thermal stability, with an increase in its wettability as compared to untreated PVC. The results showed that gamma irradiation PVC film improved mechanical properties. Young's modulus and tensile strength increased respectively from 297 MPa to 189 and 24 to 28 MPa, respectively, and the ultimate elongation increased from 124 to 154%. The gamma irradiation of the polyvinyl chloride caused significant increase of the surface tension, from 3 mN/m for the unirradiated to 5 to 11 mN/m up to 10 after irradiation at 70 kGy. (authors)

  4. Metabolic cost of SAB (The Metabolic Cost of Performing Surface Active Behaviors in Delphinids)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Surface active behaviors (SABs), such as tail slaps and breaches, are performed by cetaceans over a range of behavioral contexts. Some cetaceans perform SABs in...

  5. Mechanical Properties and Corrosion Behavior of Low Carbon Steel Weldments

    Directory of Open Access Journals (Sweden)

    Mohamed Mahdy

    2013-01-01

    Full Text Available This research involves studying the mechanical properties and corrosion behavior of “low carbon steel” (0.077wt% C before and after welding using Arc, MIG and TIG welding. The mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of TIG, MIG welding is more than arc welding, while tensile strength in arc welding more than TIG and MIG.The corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mV.sec-1 in 3.5% NaCl to show the polarization resistance and calculate the corrosion rate from data of linear polarization by “Tafel extrapolation method”. The results indicate that the TIG welding increase the corrosion current density and anodic Tafel slop, while decrease the polarization resistance compared with unwelded low carbon steel. Cyclic polarization were measured to show resistance of specimens to pitting corrosion and to calculate the forward and reveres potentials. The results show shifting the forward, reverse and pitting potentials toward active direction for weldments samples compared with unwelded sample.

  6. Understanding the high pressure properties of molecular solids and molecular surfaces deposited on hetrogeneous substrates

    Science.gov (United States)

    Etters, R. D.

    1985-01-01

    Work directed toward understanding the high pressure properties of molecular solids and molecular surfaces deposited on hetrogeneous substrates is reported. The motivation, apart from expanding our basic knowledge about these systems, was to understand and predict the properties of new materials synthesized at high pressure, including pressure induced metallic and superconducting states. As a consequence, information about the states of matter of the Jovian planets and their satellites, which are natural high pressure laboratories was also provided. The work on molecular surfaces and finite two and three dimensional clusters of atoms and molecules was connected with the composition and behavior of planetary atmospheres and on the processes involved in forming surface layers, which is vital to the development of composite materials and microcircuitry.

  7. Observation of modified radiative properties of cold atoms in vacuum near a dielectric surface

    CERN Document Server

    Ivanov, V V; Van den Heuvell, H B L; Spreeuw, R J C

    2004-01-01

    We report on measurements of the radiative properties of cold $^{87}$Rb atoms close to a dielectric-vacuum interface. This is the first observation of a quantum electrodynamic (QED) modification of radiative properties in vacuum near a dielectric surface. A cloud of cold atoms was created using a magneto-optical trap (MOT) and optical molasses cooling. Evanescent waves (EW) were used to observe the behavior of the atoms near the surface. We observed an increase of the natural linewidth with up to 25% with respect to the free-space value. We attribute this to QED broadening and level shifts, as well as local Stark shifts near the surface. By varying the characteristic EW length we have observed a position dependence characteristic for QED.

  8. Effects of substrate properties on the hydraulic and thermal behavior of a green roof

    Science.gov (United States)

    Sandoval, V. P.; Suarez, F. I.; Victorero, F.; Bonilla, C.; Gironas, J. A.; Vera, S.; Bustamante, W.; Rojas, V.; Pasten, P.

    2014-12-01

    Green roofs are a sustainable urban development solution that incorporates a growing media (also known as substrate) and vegetation into infrastructures to reach additional benefits such as the reduction of: rooftop runoff peak flows, roof surface temperatures, energy utilized for cooling/heating buildings, and the heat island effect. The substrate is a key component of the green roof that allows achieving these benefits. It is an artificial soil that has an improved behavior compared to natural soils, facilitating vegetation growth, water storage and typically with smaller densities to reduce the loads over the structures. Therefore, it is important to study the effects of substrate properties on green roof performance. The objective of this study is to investigate the physical properties of four substrates designed to improve the behavior of a green roof, and to study their impact on the efficiency of a green roof. The substrates that were investigated are: organic soil; crushed bricks; a mixture of mineral soil with perlite; and a mixture of crushed bricks and organic soil. The thermal properties (thermal conductivity, volumetric heat capacity and thermal diffusivity) were measured using a dual needle probe (Decagon Devices, Inc.) at different saturation levels, and the hydraulic properties were measured with a constant head permeameter (hydraulic conductivity) and a pressure plate extractor (water retention curve). This characterization, combined with numerical models, allows understanding the effect of these properties on the hydraulic and thermal behavior of a green roof. Results show that substrates composed by crushed bricks improve the thermal insulation of infrastructures and at the same time, retain more water in their pores. Simulation results also show that the hydraulic and thermal behavior of a green roof strongly depends on the moisture content prior to a rainstorm.

  9. Surface properties of polyethylene modified by atmospheric plasma

    Czech Academy of Sciences Publication Activity Database

    Novák, I.; Števiar, M.; Chodák, I.; Kuruc, Š.; Mosnáček, J.; Chehimi, M. M.; Špírková, Milena; Kleinová, A.

    Bratislava: Polymer Institute of the Slovak Academy of Sciences, 2006. s. 38-L1/2. [International Polymer Workshop /2./ From Polymer Modification to Multicomponent System. 26.11.2006-28.11.2006, Bratislava - Smolenice] Institutional research plan: CEZ:AV0Z40500505 Keywords : plasma modification * low-density polyethylene LDPE * surface properties Subject RIV: CF - Physical ; Theoretical Chemistry

  10. Properties of corona discharge plasma near metal surface

    Science.gov (United States)

    Lavrinenko, M.; Biktashev, E.; Kirko, D.

    2016-01-01

    Properties of corona discharge near metallic surface were researched. Electrical oscillations in discharge plasma of 1 kHz - 100 MHz rate were registered. Spectrum of electrical oscillations in this range was obtained. Possible plasma waves for observed electronic oscillations explanation are discussed.

  11. A first-principles study of PuN (0 0 1) surface properties

    International Nuclear Information System (INIS)

    The properties of PuN (0 0 1) surface have been investigated using all-electron full-potential linearized augmented plane wave plus local orbitals basis (FP-LAPW+lo) method at both scalar- and fully- relativistic levels, with and without spin-polarization. The ground state of PuN (0 0 1) surface is found to be ferromagnetic with spin–orbit coupling (FM + SO). At the ground state, the semi-infinite surface energy and average work function for PuN (0 0 1) surface are predicted to be 1.12 J/m2 and 2.62 eV, respectively. At three layers of formula units and beyond, the PuN (0 0 1) surface properties including total energies per N-formula unit, surface energy, work function and magnetic moment converge, indicating that a 3-layer slab can be used to model PuN (0 0 1) surface to a good approximation. The localization of the 5f electron states is pronounced at the top surface layer while bulk-like behavior is exhibited at the second and deeper layers

  12. Radar Reflection and Scattering Properties from Geologic Surfaces

    Science.gov (United States)

    Arcone, S. A.; Finnegan, D.; Yankielun, N. E.; Koh, Y.

    2005-12-01

    Planetary and terrestrial surfaces are commonly examined through the use of various radar imaging techniques, sounders and reflectivity measurements. Through these measurements we can derive a better understanding of specific geologic surface processes both visually and mathematically. Using field and laboratory observations we seek to statistically infer geologic properties of rough surfaces using radar reflectivity measurements and accurate topographic data acquired from airborne LIDAR. Well established radar theory for slightly rough and random surfaces predicts a transition from a highly peaked Gaussian distribution of normal incidence backscatter amplitude for smooth surfaces, to a broader, Rayleigh distribution as roughness approaches a significant fraction of a wavelength. This transition defines changes from reflection to scattering as a surface character alters. However, the RMS height variances of most naturally occurring surfaces are considerably greater than the standard microwave wavelengths used for most contemporary Synthetic Aperture Radar (SAR) imaging systems. Our field work was conducted at a remote watershed within California's Mojave Desert where we utilized an elevated, 1.5-GHz FMCW radar to measure backscatter at normal incidence over a rough boulder surface. In addition, we used NASA's Airborne Topographic Mapper (ATM)-LIDAR and field measurements to characterize surface slopes and height variances, and GPR to measure ground dielectric permittivity. Our lab work utilizes 100-GHz Doppler FMCW radar to measure forward scatter and backscatter at low incidence angles from various surfaces on a rotating table. All of our rough backscatter cases show Rayleigh distributions, while many of our forward scatter cases are Gaussian despite the extreme roughness. In the latter case however, the distributions are not sharp, in contradiction to the specular reflections commonly believed for grazing angle incidence. Our preliminary conclusions show that it

  13. Functional properties of laser modified surface of tool steel

    Directory of Open Access Journals (Sweden)

    M. Bonek

    2006-04-01

    Full Text Available Purpose: Investigations include alloying the surface of X40CrMoV5-1 hot-work tool steel with tungsten carbide using a high power diode laser (HPDL.Design/methodology/approach: The structural mechanism of surface layer development was determined and the effect of alloying parameters, gas protection method, and thickness of paste layer applied onto the steel surface on structure refinement and influence of these factors on the mechanical properties of surface layer was studied.Findings: The fine grained martensite structure is responsible for hardness increase of the alloyed layer. The dependence is presented of micro-hardness change on the laser beam effect on the treated surface, and especially the hardness increase in the alloyed layer. The tribological wear relationships were determined for laser treated surface layers, determining friction coefficient, mass loss, and wear trace shape developed due to the abrasive wear of the investigated surfaces. The X40CrMoV5-1 conventionally heat treated steel was used as reference material.Practical implications: Laser surface modification has the important cognitive significance and gives grounds to the practical employment of these technologies for forming the surfaces of new tools and regeneration of the used ones.Originality/value: The outcome of the research is an investigation showing the structural mechanisms accompanying laser alloying.

  14. Improvement of carbon fiber surface properties using electron beam irradiation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Carbon fiber-reinforced advance composites have been used for struetural applications, mainly on account of their mechanical properties. The main factor for a good mechanical performance of carbon fiber-reinforced composite is the interfacial interaction between its components, which are carbon fiber and polymeric matrix. The aim of this study is to improve the surface properties of the carbon fiber using ionizing radiation from an electron beam to obtain better adhesion properties in the resultant composite. EB radiation was applied on the carbon fiber itself before preparing test specimens for the mechanical tests. Experimental results showed that EB irradiation improved the tensile strength of carbon fiber samples. The maximum value in tensile strength was reached using doses of about 250kGy. After breakage, the morphology aspect of the tensile specimens prepared with irradiated and non-irradiated carbon fibers were evaluated. SEM micrographs showed modifications on the carbon fiber surface.

  15. Enhancing the Properties of Carbon and Gold Substrates by Surface Modification

    Energy Technology Data Exchange (ETDEWEB)

    Jennifer Anne Harnisch

    2002-06-27

    The properties of both carbon and gold substrates are easily affected by the judicious choice of a surface modification protocol. Several such processes for altering surface composition have been published in literature. The research presented in this thesis primarily focuses on the development of on-column methods to modify carbon stationary phases used in electrochemically modulated liquid chromatography (EMLC). To this end, both porous graphitic carbon (PGC) and glassy carbon (GC) particles have been modified on-column by the electroreduction of arenediazonium salts and the oxidation of arylacetate anions (the Kolbe reaction). Once modified, the carbon stationary phases show enhanced chromatographic performance both in conventional liquid chromatographic columns and EMLC columns. Additionally, one may also exploit the creation of aryl films to by electroreduction of arenediazonium salts in the creation of nanostructured materials. The formation of mercaptobenzene film on the surface of a GC electrode provides a linking platform for the chemisorption of gold nanoparticles. After deposition of nanoparticles, the surface chemistry of the gold can be further altered by self-assembled monolayer (SAM) formation via the chemisorption of a second thiol species. Finally, the properties of gold films can be altered such that they display carbon-like behavior through the formation of benzenehexathiol (BHT) SAMs. BHT chemisorbs to the gold surface in a previously unprecedented planar fashion. Carbon and gold substrates can be chemically altered by several methodologies resulting in new surface properties. The development of modification protocols and their application in the analytical arena is considered herein.

  16. Oxidative nanopatterning of titanium generates mesoporous surfaces with antimicrobial properties

    OpenAIRE

    Variola F; SF Zalzal; Leduc A; Barbeau J; Nanci A

    2014-01-01

    Fabio Variola,1,2 Sylvia Francis Zalzal,3 Annie Leduc,3 Jean Barbeau,3 Antonio Nanci31Faculty of Engineering, Department of Mechanical Engineering, 2Faculty of Science, Department of Physics, University of Ottawa, Ottawa, ON, 3Faculty of Dental Medicine, Université de Montréal, Montreal, QC, CanadaAbstract: Mesoporous surfaces generated by oxidative nanopatterning have the capacity to selectively regulate cell behavior, but their impact on microorganisms has not yet been explore...

  17. Oxidative nanopatterning of titanium generates mesoporous surfaces with antimicrobial properties

    OpenAIRE

    Variola, Fabio

    2014-01-01

    Fabio Variola,1,2 Sylvia Francis Zalzal,3 Annie Leduc,3 Jean Barbeau,3 Antonio Nanci31Faculty of Engineering, Department of Mechanical Engineering, 2Faculty of Science, Department of Physics, University of Ottawa, Ottawa, ON, 3Faculty of Dental Medicine, Université de Montréal, Montreal, QC, CanadaAbstract: Mesoporous surfaces generated by oxidative nanopatterning have the capacity to selectively regulate cell behavior, but their impact on microorganisms has not yet been...

  18. Bulk metallic glassy surface native oxide: Its atomic structure, growth rate and electrical properties

    International Nuclear Information System (INIS)

    Formation of a native oxide layer on the surface of bulk metallic glasses (BMGs) influences significantly the nanoscale tribological properties and mechanical behavior of the BMGs used in nanodevices. However, our knowledge of the native oxidation process on the BMG surface and structure of the corresponding oxides remains limited because the oxide layer is very thin. Here we conducted a combined state-of-the-art experimental technique study of the atomic structure, oxidations states and electrical conductivity of the native surface oxides on a Cu−Zr−Al BMG formed at ambient conditions by aberration-corrected scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS) and conductive atomic force microscopy (AFM). This allowed shedding light on the atomic structure, metal oxidation state, growth behavior and nanoscale electrical properties of the surface oxide. The conductive AFM measurements reveal that the electrical conductivity of the native oxide layer transits from the initially metallic to a nonlinear one after some air exposure, and finally changes to insulative state. These findings represent a significant step forward in the knowledge of surface oxides and open up the possibility of fabricating nanoscale electrical devices based on BMGs with controllable conductivity

  19. A new approach of tailoring wetting properties of TiO2 nanotubular surfaces

    KAUST Repository

    Isimjan, Tayirjan T.

    2012-11-01

    TiO2 nanotube layers were grown on a Ti surface by electrochemical anodization. As prepared, these layers showed a superhydrophilic wetting behavior. Modified with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES), the layers showed a superhydrophobic behavior. We demonstrate how to change the surface characteristics of the TiO2 nanotube layers in order to achieve any desirable degree of hydrophobicity between 100° to 170°. The treated superhydrophobic TiO2 nanotube layers have an advanced contact angle exceeding 165°, a receding angle more than 155°and a slide angle less than 5°. It is found that the surface morphology of the film which depends on anodization time among other variables, has a great influence on the superhydrophobic properties of the surface after PTES treatment. The hydrodynamic properties of the surface are discussed in terms of both Cassie and Wenzel mechanisms. The layers are characterized with dynamic contact angle measurements, SEM, and XPS analyses. © 2012 American Scientific Publishers.

  20. Effect of surface properties of fibres on some paper properties of mechanical and chemical pulp

    OpenAIRE

    Koljonen, Krista

    2004-01-01

    The overall goal of the thesis was to find correlations between the surface precipitates of pulps and selected strength properties of paper sheets. Special attention was paid to the surface lignin and extractives of fibres. The main surface-characterising techniques employed were electron spectroscopy for chemical analysis (ESCA), atomic force microscopy (AFM) and the polyelectrolyte titration method. In addition, a Wilhelmy balance for single fibres, time-of-flight secondary ion mass spectro...

  1. Growth processes and surface properties of diamondlike carbon films

    International Nuclear Information System (INIS)

    In this study, we compare the deposition processes and surface properties of tetrahedral amorphous carbon (ta-C) films from filtered pulsed cathodic arc discharge (PCAD) and hydrogenated amorphous carbon (a-C:H) films from electron cyclotron resonance (ECR)-plasma source ion implantation. The ion energy distributions (IEDs) of filtered-PCAD at various filter inductances and Ar gas pressures were measured using an ion energy analyzer. The IEDs of the carbon species in the absence of background gas and at low gas pressures are well fitted by shifted Maxwellian distributions. Film hardness and surface properties show a clear dependence on the IEDs. ta-C films with surface roughness at an atomic level and thin (0.3-0.9 nm) graphitelike layers at the film surfaces were deposited at various filter inductances in the highly ionized plasmas with the full width at half maximum ion energy distributions of 9-16 eV. The a-C:H films deposited at higher H/C ratios of reactive gases were covered with hydrogen and sp3 bonded carbon-enriched layers due to the simultaneous interaction of hydrocarbon species and atomic hydrogen. The effects of deposited species and ion energies on film surface properties were analyzed. Some carbon species have insufficient energies to break the delocalized π(nC) bonds at the graphitelike film surface, and they can govern film formation via surface diffusion and coalescence of nuclei. Dangling bonds created by atomic hydrogen lead to uniform chemisorption of hydrocarbon species from the ECR plasmas. The deposition processes of ta-C and a-C:H films are discussed on the basis of the experimental results

  2. Measurement for mechanical behavior and fatigue property of Cu films by nanoscale dynamic load method

    International Nuclear Information System (INIS)

    Highlights: • The Cu thin films with different thickness were prepared by magnetron sputtering. • The hardness and modulus values were measured by quasi-static test and CMX method. • The fatigue damage behaviors of the films were investigated by nanoDMA technique. • The influence factors of fatigue life for the nanoscale Cu films were discussed. - Abstract: Mechanical behavior and fatigue properties greatly influence the reliability and life of film materials. Quantitative testing of film fatigue property under dynamic load is realized on the basis of nanometers thick Cu films deposited on monocrystalline silicon substrates by magnetron sputtering system. Microstructure and surface pattern of copper films are characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Film hardness and modulus are measured by quasi-static test and continuous measurements (CMX) systems of nanomechanical testing instrument. Fatigue damage behaviors are investigated by nanoscale dynamic mechanical analysis (nanoDMA) technique. The results indicate that Cu films prepared by magnetron sputtering system present (1 1 1) preferred orientation and contain a large number of nanoscale grains with uniform texture and low roughness. As is affected by substrate and small scale effect, CMX method is more suitable than quasi-static method for the measurement of micro-mechanical properties of ultra-thin films. Fatigue dominantly happens in thinner films. Factors, like thickness, inner stress, modulus and hardness, can influence fatigue life of nanoscale Cu films

  3. Local thermal properties of the surface of Vesta

    Science.gov (United States)

    Capria, M. T.; Tosi, F.; Capaccioni, F.; De Sanctis, M. C.; Palomba, E.; Ammannito, E.; Carraro, F.; Fonte, S.; Titus, T. N.; Combe, J.-P.; Toplis, M.; Sunshine, J.; Fulchignoni, M.; Russel, C. T.; Raymond, C. A.

    2012-04-01

    Temperature information has been obtained from the Dawn/VIR (Visible InfraRed imaging spectrometer) spectra acquired during the Vesta campaign. When combined with a thermophysical model, these temperatures can be used to derive surface thermal properties. Thermal properties are sensitive to several physical characteristics of the surface that are not all spatially resolved. Thus, the derivation of surface temperatures and thermal inertia can lead to the characterization of surface and sub-surface properties of Vesta and the determination of regolith properties. The model we are using solves the heat conduction equation and provide the temperature as a function of thermal conductivity, albedo, emissivity, density and specific heat. The model is applied to the actual shape of Vesta: for any given location, characterized by a well-defined illumination condition and a given UTC time to compute the thermal inertia that results in model temperatures providing a best-fit to surface temperatures as retrieved by VIR. The model has been already applied to the first Vesta full-disk data to derive the global average thermal inertia of Vesta. The values obtained are typical of fine-grained, unconsolidated materials (i.e. dust) and suggest a surface in which a dust layer is wide-spread on coarser regolith. The model is now being applied on small regions of the surface of Vesta. Specific regions are selected because they are interesting for some reason or appear different from the surroundings, such as, for example, dark and bright spots and other peculiar features. Given a location, the thermophysical code is applied until the obtained temperatures are matching (best-fit techniques are used) the temperatures derived from the VIR spectra. The thermal inertia, thermal conductivity, albedo and roughness values are then assumed to be characterizing the location under analysis. The results of the model must be carefully checked and interpreted by taking into account the context (from

  4. Further studies of the effects of oxidation on the surface properties of coal and coal pyrite

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, M.N.

    1994-12-31

    The objective of this research was to investigate the oxidation behavior of coal and coal pyrite and to correlate the changes in the surface properties induced by oxidation, along with the intrinsic physical and chemical properties of these organic and inorganic materials, with the behavior in physical coal cleaning processes. This provide more fundamental knowledge for understanding the way in which different factors interact in a medium as heterogeneous as coal. Fourteen coal samples of different ranks ranging from high to medium sulfur content were studied by dry oxidation tests at different temperatures and humidities, and by wet oxidation tests using different oxidizing agents. The concentration of surface oxygen functional groups was determined by ion-exchange methods. The changes in the coal composition with oxidation were analyzed by spectroscopic techniques. The wettability of as-received and oxidized coal and coal pyrite samples was assessed by film flotation tests. The electrokinetic behavior of different coals and coal pyrite samples was studied by electrokinetic tests using electrophoresis. Possible oxidation mechanisms have been proposed to explain the changes on the coal surface induced by different oxidation treatments.

  5. Surface phase stability and surfactant behavior of InAsSb alloy surfaces.

    Science.gov (United States)

    Anderson, Evan M.; Lundquist, Adam M.; Pearson, Chris; Millunchick, Joanna M.

    InAsSb has the narrowest bandgap of any of the conventional III-V semiconductors: low enough for long wavelength infrared applications. Such devices are sensitive to point defects, which can be detrimental to performance. To control these defects, all aspects of synthesis must be considered, especially the atomic bonding at the surface. We use an ab initio statistical mechanics approach that combines density functional theory with a cluster expansion formalism to determine the stable surface reconstructions of Sb (As) on InAs (InSb) substrates. The surface phase diagram of Sb on InAs is dominated by Sb-dimer termination α2(2x4) and β2(2x4) and c(4x4). Smaller regions of mixed Sb-As dimers appear for high Sb chemical potentials and intermediate As chemical potential. We propose that InAsSb films could be grown on (2x4), which maintain bulk-like stoichiometry, to eliminate the formation of typically observed n-type defects. Scanning tunneling microscopy and reflection high energy electron diffraction confirm the calculated phase diagram. Based on these calculations, we propose a new mechanism for the surfactant behavior of Sb in these materials. We gratefully acknowledge Chakrapani Varanasi and the support of the Department of Defense, Army Research Office via the Grant Number W911NF-12-1-0338.

  6. Influence of Combined Hard and Fine Machining on the Surface Properties of Cemented Carbides

    Directory of Open Access Journals (Sweden)

    U. Engel

    2012-09-01

    Full Text Available As a result of recent developments in cold forging cemented carbides are increasingly used as tool materials. Due to their high hardness only electrical discharge machining (EDM and grinding are suitable for tool machining. The structure of tool surface has significant influence on dominating failure mechanisms wear and fatigue. For improvement of tribological conditions the surface is polished in a finale processing step. The result of hard and fine machining is a specific combination of coarse and fine structure which is determined by processing parameters. The different surface structures lead to a particular tool behavior in forming process. This paper aims to show the influence of combined hard and fine machining on the surface properties of cemented carbides.

  7. The Change in Surface Area Properties of Blast Furnace

    Directory of Open Access Journals (Sweden)

    Rađenović, A.

    2009-04-01

    Full Text Available Blast furnace sludge-BFS is a by-product and waste material of the iron and steel industry. Recently, the adsorption capabilities of blast furnace sludge have been attracting great interest. It is known that materials with modified surface properties can be obtained by different chemical and thermal treatments.The aim of this work was to investigate the influence of chemical treatment by acetic acid and thermal treatment by heating at 700 °C, on the surface properties of blast furnace sludge. Chemical treatment was performed by acetic acid adsorption on BFS.Microscopic observation was conducted using scanning electron microscopy (SEM method. Changes in examined surface area properties were analyzed by Brunauer-Emmett-Teller (BET and Barrett-Joyner-Halenda (BJH methods.Increasing of specific surface area, decreasing of pore size and better pore size distribution in BFS samples were registered after the applied experimental procedure. The obtained results revealed that the performed chemical and heat treatment presented the activation of blast furnace sludge.

  8. Mechanical and Wear Properties of Nanostructured Surface Layer in Iron Induced by Surface Mechanical Attrition Treatment

    Institute of Scientific and Technical Information of China (English)

    Nairong TAO; Weiping TONG; Zhenbo WANG; Wei WANG; Manling SUI; Jian LU; Ke LU

    2003-01-01

    A porosity-free and contamination-free surface layer with grain sizes ranging from nanometer to micrometer in Fe samples was obtained by surface mechanical attrition treatment (SMAT) technique. Mechanical and wear properties of the surface layer in the SMATed and annealed Fe samples were measured by means of nanoindentation and nanoscratch tests, respectively. Experimental results showed that the hardness of the surface layer in the SMATed Fe sample increased evidently due to the grain refinement. The elastic noduli of the surface layers in the SMATed and annealed Fe samples were unchanged, independent of grain size in the present grain size regime. Compared with the original Fe sample, the wear resistance enhanced and the coefficient of friction decreased in the surface layer of the SMATed Fe sample.

  9. Phase behavior of miscible block copolymer blends and baraplastic property

    International Nuclear Information System (INIS)

    The phase behavior of the multi-component polymer systems such as blends and block copolymers (BCPs) has been studied extensively, as it determines the chemical and physical properties of the polymeric materials in practical applications. Above all, polymer baroplasticity is a desirable property for the recycling and regenerating industries, since it allows the polymers to flow at relatively mild pressure. Particularly, the compressibility issue on the enhanced miscibility with pressure has been an attractive topic, because an ordered state of the baroplastic BCPs becomes a phase-mixed state (or disordered phase) between the two dissimilar blocks upon pressurizing. This is in contrast to the incompressibility that was dictated by the enthalpic effect arising from the increased unfavorable contacts between the two blocks by increasing pressure. The phase behaviors of BCP blends composed of the weakly interacting (with no specific interaction) polystyrene-b-poly(n-butyl methacrylate) (PS-b-PnBMA) and deuterated polystyreneb- poly-(n-hexyl methacrylate) (dPS-b-PnHMA) were investigated by Small-Angle Neutron Scattering(SANS) and Depolarized Light Scattering (DPLS) measurements. Interestingly, pressure dependence of various phase transitions for the miscible BCP blends was significantly changed, in which the blends consist of a PS-b-PnBMA and a deuterated dPS-b-PnHMA. To elucidate the origin and difference in baroplasticity of weakly interacting BCP blends, the pressure dependence of transition temperatures was evaluated using enthalpic and volumetric changes at phase transitions. We also demonstrate that the entropic compressibility for the miscible BCP blends is a baroplastic indicator, which was characterized by the negative volume change on mixing (ΔVmix) at transitions.

  10. Atomistic Simulation of Properties of Ultra-thin Layer of Liquid Argon Compressed Between Diamond Surfaces

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2016-03-01

    Full Text Available Using the method of classical molecular dynamics we investigate the properties of ultrathin film of liquid argon, which consists of one or two layers of molecules and is confined by two atomically smooth crystalline diamond surfaces. The aim of the research is validating the use of rigid surfaces and one of the available models of the argon molecule. We study the behavior of the equilibrium and dynamic characteristics of the system. It is shown that at increasing external load the transition of film in the solid-like state occurs, which is indicated by the behavior of the velocity autocorrelation function of argon molecules, reduction of the magnitude of the diffusion coefficient and the shear viscosity increase. The organization of molecules in layers and the presence of their in-plane ordering are revealed. The dependences of the kinetic friction force on time and load are obtained. The results are compared with experimental data.

  11. Microstructure and properties of cast iron after laser surface hardening

    Directory of Open Access Journals (Sweden)

    Stanislav

    2013-12-01

    Full Text Available Laser surface hardening of cast iron is not trivial due to the material’s heterogeneity and coarse-grained microstructure, particularly in massive castings. Despite that, hardening of heavy moulds for automotive industry is in high demand. The present paper summarises the findings collected over several years of study of materials structure and surface properties. Phase transformations in the vicinity of graphite are described using examples from production of body parts in automotive industry. The description relates to formation of martensite and carbide-based phases, which leads to hardness values above 65 HRC and to excellent abrasion resistance.

  12. Modification of optical properties of copper surfaces by ion bombardment

    International Nuclear Information System (INIS)

    Influence of ion bombardment by N2+, N2+ and D+ ions on optical properties of copper films evaporated on single crystal silicon wafer and samples of balk Cu was studied. Microrelief of surface of the copper samples was studied by optical microscopy. It was found that principal incidence angle and optical conductivity of Cu subsurface layer decrease after nitrogen ion bombardment. Additional irradiation by N2+ ions does not improve corrosion stability of Cu films. It was obtained that interaction of D+ ions with subsurface layer of Cu increases the roughness of surface and essentially changes the spectra of optical conductivity

  13. Structural and dynamical properties of water on chemically modified surfaces: The role of the instantaneous surface

    Science.gov (United States)

    Bekele, Selemon; Tsige, Mesfin

    Surfaces of polymers such as atactic polystyrene (aPS) represent very good model systems for amorphous material surfaces. Such polymer surfaces are usually modified either chemically or physically for a wide range of applications that include friction, lubrication and adhesion. It is thus quite important to understand the structural and dynamical properties of liquids that come in contact with them to achieve the desired functional properties. Using molecular dynamics (MD) simulations, we investigate the structural and dynamical properties of water molecules in a slab of water in contact with atactic polystyrene surfaces of varying polarity. We find that the density of water molecules and the number distribution of hydrogen bonds as a function of distance relative to an instantaneous surface exhibit a structure indicative of a layering of water molecules near the water/PS interface. For the dynamics, we use time correlation functions of hydrogen bonds and the incoherent structure function for the water molecules. Our results indicate that the polarity of the surface dramatically affects the dynamics of the interfacial water molecules with the dynamics slowing down with increasing polarity. This work was supported by NSF Grant DMR1410290.

  14. Fatigue behavior of plain C–Mn steel plates with fine grained ferrite in surface layers

    International Nuclear Information System (INIS)

    Highlights: ► Grain refinement can improve effectively the fatigue properties of C–Mn steel plates. ► The area of fatigue striations in plate with fine grained ferrite is less than that with coarse grained ferrite. ► The ferrite grain refinement in the surface layers of the steel plates can hold back or postpone the formation of surface fatigue cracks. ► The banding pearlite can promote the formation and extension of the secondary cracks. - Abstract: The effect of fine-grained surface layers on the fatigue behavior of plain C–Mn steel plates is investigated. The plain C–Mn steel plates have been manufactured by a special thermo-mechanical controlled process (TMCP). For plates rolled by the special TMCP (designated special plates), the ferrite grain size approaches 5.5 μm in the surface layers and reaches 6.5 μm on average in the whole thickness of the plates, while for usually rolled plates (designated usual plates), the grain size is 15 μm on average in the whole thickness of the plates, without obvious difference between surface and central layers. Significant improvements of fatigue properties have been achieved by the ferrite grain refinement. Under the similar stress condition, the fatigue lifetime of the special plate is more than 10 times as long as that of the usual plate, and the first stage of fatigue crack propagation can be prolonged. With a similar lifetime of the usual plate under a load ratio R (σmin/σmax) approaching zero, the special plate can sustain a load 40 MPa higher than that of the usual plate. Furthermore, fatigue fractographs have been observed and analyzed by a scanning electron microscope (SEM).

  15. The surface modification of stainless steel and the correlation between the surface properties and protein adsorption.

    Science.gov (United States)

    Kang, Chan-Koo; Lee, Yoon-Sik

    2007-07-01

    Protein adsorption on a biomaterial surface is of great importance as it usually induces unfavorable biological cascades, with the result that much surface modification research has had to be performed in an effort to prevent this. In this study, we developed surface modification methods for stainless steel, which is a representative metal for biomedical device. The stainless steels were first smoothened to different extents by electropolishing, in order to obtain a rough or smooth surface. On these two kinds of substrates, we introduced epoxide groups to the metal surface by silanization with 3-glycidoxypropyltrimethoxysilane (GPTS). Then, various polymers such as poly(ethylene glycol) (PEG), poly(tetrahydrofuran glycol) (PTG), poly(propylene glycol) (PPG) and poly(dimethylsiloxane) (PDMS) were grafted on the silanized stainless steels. Each surface modification step was confirmed by various analytical methods. Contact angle measurement revealed that the surface hydrophilicity was controllable by polymer grafting. Root-mean-square (RMS) data of atomic force microscopy showed that surface roughness was dramatically changed by electropolishing. Based on these results, the correlation between surface properties and protein adsorption was investigated. In the protein adsorption study, we observed that all of the polymer-grafted stainless steels exhibited lower protein adsorption, when compared with bare stainless steel. Moreover, a hydrophilic and smooth surface was found to be the best of choice for decreasing the protein adsorption. PMID:17277988

  16. Correlation between surface microstructure and optical properties of porous silicon

    Directory of Open Access Journals (Sweden)

    Saeideh Rhramezani Sani

    2007-12-01

    Full Text Available   We have studied the effect of increasing porosity and its microstructure surface variation on the optical and dielectric properties of porous silicon. It seems that porosity, as the surface roughness within the range of a few microns, shows quantum effect in the absorption and reflection process of porous silicon. Optical constants of porous silicon at normal incidence of light with wavelength in the range of 250-3000 nm have been calculated by Kramers-Kroning method. Our experimental analysis shows that electronic structure and dielectric properties of porous silicon are totally different from silicon. Also, it shows that porous silicon has optical response in the visible region. This difference was also verified by effective media approximation (EMA.

  17. Friction Properties of Surface-Fluorinated Carbon Nanotubes

    Science.gov (United States)

    Wal, R. L. Vander; Miyoshi, K.; Street, K. W.; Tomasek, A. J.; Peng, H.; Liu, Y.; Margrave, J. L.; Khabashesku, V. N.

    2005-01-01

    Surface modification of the tubular or sphere-shaped carbon nanoparticles through chemical treatment, e.g., fluorination, is expected to significantly affect their friction properties. In this study, a direct fluorination of the graphene-built tubular (single-walled carbon nanotubes) structures has been carried out to obtain a series of fluorinated nanotubes (fluoronanotubes) with variable C(n)F (n =2-20) stoichiometries. The friction coefficients for fluoronanotubes, as well as pristine and chemically cut nanotubes, were found to reach values as low as 0.002-0.07, according to evaluation tests run in contact with sapphire in air of about 40% relative humidity on a ball-on-disk tribometer which provided an unidirectional sliding friction motion. These preliminary results demonstrate ultra-low friction properties and show a promise in applications of surface modified nanocarbons as a solid lubricant.

  18. CERMET fuel behavior and properties in ADS reactors

    International Nuclear Information System (INIS)

    Within the EUROTRANS Integrated Project, Forschungszentrum Karlsruhe (FZK) and the Institute for Transuranium Elements (ITU) are joining their efforts to study the behavior of Mo-based CERMET non-uranium fuel for the ADS. Contributions include core safety calculations, and fuel property measurements and irradiation experiments. Safety studies for optimized EFIT core designs have concluded that, for the new low power cores of EFIT with a power class of ∼400 MWth and a fuel power density of ∼250 MW/m3, the CERMET-loaded cores behave favorably and the design limits of the fuels were not violated. Mo-based CERMET fuel pellets and pins loaded with Pu and Am were fabricated for irradiation programmes which will start by mid-2007 in PHENIX (France) and HFR-Petten (The Netherlands). The thermal diffusivity and specific heat of the CERMET fuels (loaded with Pu and Am) were the main properties measured, and the thermal conductivity was deduced. The results were used to prepare the safety report for the irradiation experiments

  19. Chondrocyte behavior on nanostructured micropillar polypropylene and polystyrene surfaces

    International Nuclear Information System (INIS)

    This study was aimed to investigate whether patterned polypropylene (PP) or polystyrene (PS) could enhance the chondrocytes' extracellular matrix (ECM) production and phenotype maintenance. Bovine primary chondrocytes were cultured on smooth PP and PS, as well as on nanostructured micropillar PP (patterned PP) and PS (patterned PS) for 2 weeks. Subsequently, the samples were collected for fluorescein diacetate-based cell viability tests, for immunocytochemical assays of types I and II collagen, actin and vinculin, for scanning electronic microscopic analysis of cell morphology and distribution, and for gene expression assays of Sox9, aggrecan, procollagen α1(II), procollagen α1(X), and procollagen α2(I) using quantitative RT-PCR assays. After two weeks of culture, the bovine primary chondrocytes had attached on both patterned PP and PS, while practically no adhesion was observed on smooth PP. However, the best adhesion of the cells was on smooth PS. The cells, which attached on patterned PP and PS surfaces synthesized types I and II collagen. The chondrocytes' morphology was extended, and an abundant ECM network formed around the attached chondrocytes on both patterned PP and PS. Upon passaging, no significant differences on the chondrocyte-specific gene expression were observed, although the highest expression level of aggrecan was observed on the patterned PS in passage 1 chondrocytes, and the expression level of procollagen α1(II) appeared to decrease in passaged chondrocytes. However, the expressions of procollagen α2(I) were increased in all passaged cell cultures. In conclusion, the bovine primary chondrocytes could be grown on patterned PS and PP surfaces, and they produced extracellular matrix network around the adhered cells. However, neither the patterned PS nor PP could prevent the dedifferentiation of chondrocytes. - Highlights: • Methods to avoid chondrocyte dedifferentiation would be useful for cartilage repair. • Cell culture

  20. Correlation properties of surface and percolation transfer of electrons

    International Nuclear Information System (INIS)

    In this work was received equation, connecting correlatively properties of surface with electrons distribution function. Usually for equilibrium is necessary a large number of collisions. Collisions are 'destroying' correlations. In case rare collisions large importance have correlations and 'memory' effects. Non-Markov's character of emitting particles by surface lead to strongly nonequilibrium condition of 'gas'. Here kinetic equation of diffusive form does not apply. Classical kinetic equation are described only conditions near to equilibrium. This work offers to use ideas anomal diffusion in phase-space. The correlation properties of surface describe by correlations of velocities of emitting electrons: B(t). We offer to use functional equation for probability collision instead of kinetic equation: ∫0ν0WnoncollF(ν) dv = 1 - B(t). This functional allow to consider 'memory' effects. It is important for consideration of electrons and clusters near surfaces. Distribution function become direct connected with correlations. In classical Kubo-Mory theory of transfer is necessary to get nondivergences integral: D ∝ ∫0∞B(t). In considering case we can use even 'power function'. It was used 'slow' correlation function as Kohlraush in calculations. The information about kinetics and correlations properties are containing in one functional equation. It was received solution of this equation in form Levy function: F(ν) ∝ 1/να exp(-1/ν). The solution of this form can not be get with help asymptotic methods of kinetic theory. Asymptotics of solution have scale-invariant character F(V) ∝ 1/Vα. This indicate on fractal properties phase-space. (author)

  1. Distance Measurements and Stellar Population Properties via Surface Brightness Fluctuations

    OpenAIRE

    Fritz, Alexander

    2012-01-01

    Surface Brightness Fluctuations (SBFs) are one of the most powerful techniques to measure the distance and to constrain the unresolved stellar content of extragalactic systems. For a given bandpass, the absolute SBF magnitude \\bar{M} depends on the properties of the underlying stellar population. Multi-band SBFs allow scientists to probe different stages of the stellar evolution: UV and blue wavelength band SBFs are sensitive to the evolution of stars within the hot Horizontal Branch (HB) and...

  2. Plasma modification of HEMA and EOEMA surface properties

    Czech Academy of Sciences Publication Activity Database

    Švorčík, V.; Kolářová, K.; Dvořánková, B.; Michálek, Jiří; Krumbholcová, Eva; Hnatowicz, Vladimír

    2006-01-01

    Roč. 161, č. 1 (2006), s. 15-19. ISSN 1042-0150 R&D Projects: GA ČR GA106/03/0514; GA AV ČR IAA5011301 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z10480505 Keywords : polymer * plasma modification * surface properties Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.497, year: 2006

  3. Properties of axial surface waves along dielectrically coated conducting cylinders

    OpenAIRE

    Siart, U.; Adrian, S.; Eibert, T.

    2012-01-01

    In this paper the fundamental properties of surface waves along conducting cylinders with and without dielectric coating are investigated for cylinder diameters in the centimeter range and frequencies in the gigahertz range and higher. Analytical results for the phase constant and attenuation versus the cylinder radius are derived and cutoff frequencies of various TE, TM, and hybrid waves are computed. The radial power distribution is computed in order to investi...

  4. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    OpenAIRE

    Bashar Issa; Obaidat, Ihab M.; Albiss, Borhan A.; Yousef Haik

    2013-01-01

    Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm), viruses, genes, down to proteins (3–50 nm). The opti...

  5. The surface properties of biopolymer-coated fruit: A review

    OpenAIRE

    Diana Cristina Moncayo Martinez; Gustavo Buitrago Hurtado; Néstor Ariel Algecira Enciso

    2012-01-01

    Environmental conservation concerns have led to research and development regarding biodegradable materials from biopolymers, leading to new formulations for edible films and coatings for preserving the quality of fresh fruit and vegetables. Determining fruit skin surface properties for a given coating solution has led to predicting coating efficiency. Wetting was studied by considering spreading, adhesion and cohesion and measuring the contact angle, thus optimising the coating formulation in...

  6. Influence of the structural properties on the pseudocritical magnetic behavior of single-wall ferromagnetic nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Salazar-Enriquez, C.D. [PCM Computational Applications, Universidad Nacional de Colombia - Sede Manizales, A.A. 127 Manizales (Colombia); Restrepo-Parra, E., E-mail: erestrepopa@unal.edu.co [PCM Computational Applications, Universidad Nacional de Colombia - Sede Manizales, A.A. 127 Manizales (Colombia); Restrepo, J. [Grupo de Magnetismo y Simulacion Gplus, Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia)

    2012-04-15

    In this work we address the influence of the crystalline structure, concretely when the system under study is formed by square or hexagonal unit cells, upon the magnetic properties and pseudocritical behavior of single-wall ferromagnetic nanotubes. We focus not only on the effect of the geometrical shape of the unit cell but also on their dimensions. The model employed is based on the Monte Carlo method, the Metropolis dynamics and a nearest neighbors classical Heisenberg Hamiltonian. Magnetization per magnetic site, magnetic susceptibility, specific heat and magnetic energy were computed. These properties were computed varying the system size, unit cell dimension and temperature. The dependence of the nearest neighbor exchange integral on the nanotubes geometrical characteristics is also discussed. Results revealed a strong influence of the system topology on the magnetic properties caused by the difference in the coordination number between square and hexagonal unit cell. Moreover, the nanotubes diameter influence on magnetic properties is only observed at very low values, when the distance between atoms is less than it, presented by the 2D sheet. On the other hand, it was concluded that the surface-related finite-size effects do not influence the magnetic nanotubes properties, contrary to the case of other nano-systems as thin films and nanoparticles among others. - Highlights: Black-Right-Pointing-Pointer Unit cell geometry has strong influence on the magnetic properties in ferromagnetic nanotubes. Black-Right-Pointing-Pointer The nanotube diameter increase produces a decrease of interaction between nearest neighbor. Black-Right-Pointing-Pointer Surface-related finite-size effects do not influence the magnetic nanotubes properties.

  7. Effect of Surface Treatment on the Properties of Wool Fabric

    Science.gov (United States)

    Kan, C. W.; Yuen, C. W. M.; Chan, C. K.; Lau, M. P.

    Wool fiber is commonly used in textile industry, however, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling, and dyeability. These problems may be attributed mainly in the presence of wool scales on the fiber surface. Recently, chemical treatments such as oxidation and reduction are the commonly used descaling methods in the industry. However, as a result of the pollution caused by various chemical treatments, physical treatment such as low temperature plasma (LTP) treatment has been introduced recently because it is similarly capable of achieving a comparable descaling effect. Most of the discussions on the applications of LTP treatment on wool fiber were focused on applying this technique for improving the surface wettability and shrink resistance. Meanwhile, little discussion has been made on the mechanical properties, thermal properties, and the air permeability. In this paper, wool fabric was treated with LTP treatment with the use of a non-polymerizing gas, namely oxygen. After the LTP treatment, the fabrics low-stress mechanical properties, air permeability, and thermal properties were evaluated and discussed.

  8. Preacclimation alters Salmonella Enteritidis surface properties and its initial attachment to food contact surfaces.

    Science.gov (United States)

    Yang, Yishan; Kumar, Amit; Zheng, Qianwang; Yuk, Hyun-Gyun

    2015-04-01

    Exposure of Salmonella to environmental stress, prior to its adherence to a food contact surface, may change the cell surface properties and consequently affect its initial attachment and biofilm formation. This study investigated the influence of temperature and pH preacclimation on the initial attachment of Salmonella Enteritidis to acrylic and stainless steel. Besides, changes in physicochemical properties of cells were examined; and their surface attachment was modeled by xDLVO theory. Results showed that control cells pre-grown at 37°C had significantly (P0.05) different from control cells pre-grown at pH 7.3, but they were significantly higher compared to cells pre-grown at pH 8.3 and 9.0. No significant difference was observed between cell attachment to acrylic and stainless steel, although they had different physicochemical properties. The xDLVO theory successfully explained higher attachment for cells pre-grown at optimal condition on both contact surfaces. However, the xDLVO theory could not explain the similar attachment of cells to acrylic and stainless steel. This study elucidates that commonly used intervention technologies including cold storage, thermal treatment, and alkaline antimicrobial agents might alter the physicochemical properties of S. Enteritidis cells and result in varied initial attachment levels. PMID:25800356

  9. Hydrodynamics of slip wedge and optimization of surface slip property

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The hydrodynamic load support generated by a slip wedge of a slider bearing was studied. The surface slip property was optimized so that a maximum hydrodynamic load support could be obtained. A multi-linearity method was given for the slip control equation of two-dimensional (2-D) wall slip. We investigated 2-D wall slip and the hydrodynamics of a finite length bearing with any values of the surface limiting shear stress. It was found that the hydrodynamic effect of the slip wedge is greater than the traditional geometrical convergent-wedge. Even though the geo- metrical gap is a parallel or divergent sliding gap, the slip wedge still gives rise to a very big hydrodynamic pressure. The optimized slip wedge can give rise to a hy- drodynamic load support as high as 2.5 times of what the geometrical conver- gent-wedge can produce. Wall slip usually gives a small surface friction.

  10. Hydrodynamics of slip wedge and optimization of surface slip property

    Institute of Scientific and Technical Information of China (English)

    MA GuoJun; WU ChengWei; ZHOU Ping

    2007-01-01

    The hydrodynamic load support generated by a slip wedge of a slider bearing was studied. The surface slip property was optimized so that a maximum hydrodynamic load support could be obtained. A multi-linearity method was given for the slip control equation of two-dimensional (2-D) wall slip. We investigated 2-D wall slip and the hydrodynamics of a finite length bearing with any values of the surface limiting shear stress. It was found that the hydrodynamic effect of the slip wedge is greater than the traditional geometrical convergent-wedge. Even though the geometrical gap is a parallel or divergent sliding gap, the slip wedge still gives rise to a very big hydrodynamic pressure. The optimized slip wedge can give rise to a hydrodynamic load support as high as 2.5 times of what the geometrical convergent-wedge can produce. Wall slip usually gives a small surface friction.

  11. Radiative Properties of Smoke and Aerosol Over Land Surfaces

    Science.gov (United States)

    King, Michael D.

    2000-01-01

    This talk discusses smoke and aerosol's radiative properties with particular attention to distinguishing the measurement over clear sky from clouds over land, sea, snow, etc. surfaces, using MODIS Airborne Simulator data from (Brazil, arctic sea ice and tundra and southern Africa, west Africa, and other ecosystems. This talk also discusses the surface bidirectional reflectance using Cloud Absorption Radiometer, BRDF measurements of Saudi Arabian desert, Persian Gulf, cerrado and rain forests in Brazil, sea ice, tundra, Atlantic Ocean, Great Dismal Swamp, Kuwait oil fire smoke. Recent upgrades to instrument (new TOMS UVA channels at 340 and 380 planned use in Africa (SAFARI 2000) and possibly for MEIDEX will also be discussed. This talk also plans to discuss the spectral variation of surface reflectance over land and the sensitivity of off-nadir view angles to correlation between visible near-infrared reflectance for use in remote sensing of aerosol over land.

  12. Surface Properties of Photo-Oxidized Bituminous Coals: Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-09-01

    Natural weathering has a detrimental effect on the hydrophobic nature of coal, which in turn can influence clean-coal recovery during flotation. Few techniques are available that can establish the quality of coal surfaces and that have a short analysis time to provide input for process control. Luminescence emissions which can be quantified with an optical microscope and photometer system, are measurably influenced by degree of weathering as well as by mild storage deterioration. In addition, it has been shown that when vitrinite is irradiated with a relatively high intensity flux of violet- or ultraviolet- light in the presence of air, photo-oxidation of the surface occurs. The combination of measuring the change in luminescence emission intensity with degree of surface oxidation provided the impetus for the current investigation. The principal aim of this research was to determine whether clear correlations could be established among surface oxygen functionality, hydrophobicity induced by photo-oxidation, and measurements of luminescence intensity and alteration. If successful, the project would result in quantitative luminescence techniques based on optical microscopy that would provide a measure of the changes in surface properties as a function of oxidation and relate them to coal cleanability. Two analytical techniques were designed to achieve these goals. Polished surfaces of vitrain bands or a narrow size fraction of powdered vitrain concentrates were photo-oxidized using violet or ultraviolet light fluxes and then changes in surface properties and chemistry were measured using a variety of near-surface analytical techniques. Results from this investigation demonstrate that quantitative luminescence intensity measurements can be performed on fracture surfaces of bituminous rank coals (vitrains) and that the data obtained do reveal significant variations depending upon the level of surface oxidation. Photo-oxidation induced by violet or ultraviolet light

  13. Au(111) and Pt(111) surface phase behavior

    DEFF Research Database (Denmark)

    Sandy, A.R.; Mochrie, S.G.J.; Zehner, D.M.;

    1993-01-01

    We describe our recent X-ray scattering studies of the structure and phases of the clean Au(111) and Pt(111) surfaces. Below 0.65 of their respective bulk melting temperatures, the Au(111) surface has a well-ordered chevron reconstruction and the Pt(111) surface is unreconstructed. Above these...... temperatures, both surfaces reconstruct to form layers that are isotropically compresses and have only short-range order. Throughout their reconstructed phases, the densities of the Au and Pt(111) surfaces increase with increasing temperature....

  14. Effect of surface roughness on corrosion behavior of Alloy 690TT in simulated primary coolant of PWRs

    International Nuclear Information System (INIS)

    The corrosion products transported into the primary coolant may be activated in the core or re-deposited on the surface of components in primary coolant system including fuel cladding. Nickel cations released from the steam generator tubes cause the serious problems in PWRs, for instance, radiation exposure during maintenance operation, occurrence of axial offset anomaly (AOA) and reduction in plant operation. Some studies have been carried out to characterize the oxide layer grown on a Ni-base alloy in primary water chemical condition, especially on morphology and chemical composition. The oxide layer was deemed to a duplex structure composed to an inner Cr rich layer and an outer spinel layer rich in iron or nickel. The composition and morphology of oxide layer are affected by surface finish, operating condition, and water chemistry. Above all, surface roughness, which is one of the commercial requirements for steam generator tube of PWRs, is extremely important in terms of corrosion degradation and corrosion products. In this study, we report the effect of surface roughness on corrosion behavior in simulated primary water at 330 .deg. C and at 150 bar. The surface roughness was controlled to evaluate its difference in corrosion property using mechanical grinding and polishing method. It was measured using a surface profiler and morphology of oxide layer was investigated with FESEM. The corrosion rate of Alloy 690TT samples was calculated by descale-gravimetric analysis. We investigate the effect of surface roughness on corrosion behavior of Alloy 690TT in the simulated primary coolant environments of a pressurized water reactor. Surface roughness of samples were controlled from 716 nm to 25 nm to evaluate for the effect of surface roughness on corrosion behavior Polyhedral oxide particles were formed on the grounded surfaces, whereas the mixed oxides of polyhedral and needle-like structure formed on the polished surface. The corrosion rate of samples was

  15. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi

    2014-11-11

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  16. Control of cell behavior on PTFE surface using ion beam irradiation

    International Nuclear Information System (INIS)

    A polytetrafluoroethylene (PTFE) surface is smooth and biologically inert, so that cells cannot attach to it. Ion beam irradiation of the PTFE surface forms micropores and a melted layer, and the surface is finally covered with a large number of small protrusions. Recently, we found that cells could adhere to this irradiated PTFE surface and spread over the surface. Because of their peculiar attachment behavior, these surfaces can be used as biological tools. However, the factors regulating cell adhesion are still unclear, although some new functional groups formed by irradiation seem to contribute to this adhesion. To control cell behavior on PTFE surfaces, we must determine the effects of the outermost irradiated surface on cell adhesion. In this study, we removed the thin melted surface layer by postirradiation annealing and investigated cell behavior on the surface. On the surface irradiated with 3 x 1016 ions/cm2, cells spread only on the remaining parts of the melted layer. From these results, it is clear that the melted layer had a capacity for cell attachment. When the surface covered with protrusions was irradiated with a fluence of 1 x 1017 ions/cm2, the distribution of cells changed after the annealing process from 'sheet shaped' into multicellular aggregates with diameters of around 50 μm. These results indicate that we can control cell behavior on PTFE surfaces covered with protrusions using irradiation and subsequent annealing. Multicellular spheroids can be fabricated for tissue engineering using this surface.

  17. Surface Charge and Ion Sorption Properties of Titanium Dioxide

    Science.gov (United States)

    Ridley, M. K.; Machesky, M. L.; Wesolowski, D. J.; Finnegan, M. P.; Palmer, D. A.

    2001-12-01

    The interaction of submicron metal oxide particles with natural aqueous solutions results in the hydroxylation of surface sites, which impart a pH-dependent surface charge. The charged submicron particles influence processes such as nanoparticle assembly and alteration, crystal growth rates and morphologies, colloid flocculation, and contaminant transport. The surface charge and ion sorption properties of metal-oxide particles may be studied by potentiometric titrations, using hydrogen-electrode concentration-cells or traditional glass electrodes and an autotitrator. These techniques have been used to quantify the adsorption of various ions (Na+, Rb+, Ca2+, Sr2+, Cl-) on rutile, at ionic strengths up to 1.0 molality and temperatures to 250° C. The crystalline rutile used in these studies is less than 400 nm in diameter, has a BET surface area of 17 m2/g, and the 110 and 100 faces predominate. The negative surface charge of the rutile was enhanced by increasing temperature, increasing ionic strength, and decreasing the ionic radii of the electrolyte cation. Moreover, the addition of a divalent cation significantly enhances the negative charge of the rutile surface. These data have been rationalized with the MUSIC model of Hiemestra and van Riemsdijk, and a Basic Stern layer description of the electric double layer (EDL). Model fitting of the experimental data provides binding constants for the adsorbed counterions and divalent cations, and capacitance values as well as corresponding electrical potential values of the binding planes. Recently, new studies have been initiated to determine particle size affects on the proton induced surface charge and ion sorption properties of titanium dioxide. In these studies, anatase with a BET surface area of 40 and 100 m2/g (primary particle sizes of 40 and 10 nm, respectively) is being investigated. The complexity of both the experimental and modeling procedures increases with decreasing particle size. For example, the fine

  18. Osteoblast growth behavior on porous-structure titanium surface

    Energy Technology Data Exchange (ETDEWEB)

    Tian Yuan; Ding Siyang; Peng Hui; Lu Shanming; Wang Guoping [Research Institute of Stomatology, Nanjing Medical University, Nanjing 210029 (China); Xia Lu, E-mail: shelueia@yahoo.com.cn [Research Institute of Stomatology, Nanjing Medical University, Nanjing 210029 (China); Wang Peizhi, E-mail: wangpzi@sina.com [Research Institute of Stomatology, Nanjing Medical University, Nanjing 210029 (China)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer Micro-arc oxidation technology formed a porous feature on titanium surface. Black-Right-Pointing-Pointer This porous surface accelerated adhesion, proliferation and differentiation compared with smooth surface. Black-Right-Pointing-Pointer Osteogenesis-related proteins and genes were up regulated by this porous surface. Black-Right-Pointing-Pointer It is anticipated that micro-arc oxidation surface could enhance osteoblastic activity and bone regeneration. - Abstract: A bioavailable surface generated by nano-technology could accelerate implant osteointegration, reduce healing time and enable implants to bear early loading. In this study, a nano-porous surface of titanium wafers was modified using micro-arc oxidation technique; surface of smooth titanium was used as control group. Surface characteristic was evaluated by investigating morphology, roughness and hydrophilicity of titanium wafers. In vitro studies, osteoblastic adhesion, proliferation and ALP activity, as well as gene and protein expressions relative to mineralization were assayed. Our results showed that a crater-liked nano-porous surface with greater roughness and better hydrophilicity were fabricated by micro-arc oxidation. It was further indicated that nano-porous surface could enhance adhesion, proliferation and ALP activity of osteoblasts compared with smooth surfaces. In addition, gene and protein expression of collagen-I, osteocalcin and osteopontin were also obviously increased. In summary, micro-arc oxidized techniques could form an irregular nano-porous morphology on implant surface which is favorable to improve osteoblastic function and prospected to be a potent modification of dental implant.

  19. Behavior of the surface layer magnetic system of the single crystals FeBO3 near Neel point

    International Nuclear Information System (INIS)

    The behavior of the surface and boundary layers of FeBO3 macrocrystals in the Neel point area is studied through the selective in depth Moessbauer conversion electron spectroscopy. Smooth change in the magnetic properties of the monocrystal boundary area is identified. Three characteristic magnetic layers: one located in depth from the surface, the surface one and the transition layer dividing these two layers, were selected for describing this area. It is determined that the critical index β, equal to 0.348(4) for the sample volume, grows up to the 0.51)2) value as for as it approaches the surface but it does not reach the value β = 0.8 for the surface of the Heisenberg semiinfinite model

  20. Surface properties and interaction forces of biopolymer-doped conductive polypyrrole surfaces by atomic force microscopy.

    Science.gov (United States)

    Pelto, Jani M; Haimi, Suvi P; Siljander, Aliisa S; Miettinen, Susanna S; Tappura, Kirsi M; Higgins, Michael J; Wallace, Gordon G

    2013-05-21

    Surface properties and electrical charges are critical factors elucidating cell interactions on biomaterial surfaces. The surface potential distribution and the nanoscopic and microscopic surface elasticity of organic polypyrrole-hyaluronic acid (PPy-HA) were studied by atomic force microscopy (AFM) in a fluid environment in order to explain the observed enhancement in the attachment of human adipose stem cells on positively charged PPy-HA films. The electrostatic force between the AFM tip and a charged PPy-HA surface, the tip-sample adhesion force, and elastic moduli were estimated from the AFM force curves, and the data were fitted to electrostatic double-layer and elastic contact models. The surface potential of the charged and dried PPy-HA films was assessed with Kelvin probe force microscopy (KPFM), and the KPFM data were correlated to the fluid AFM data. The surface charge distribution and elasticity were both found to correlate well with the nodular morphology of PPy-HA and to be sensitive to the electrochemical charging conditions. Furthermore, a significant change in the adhesion was detected when the surface was electrochemically charged positive. The results highlight the potential of positively charged PPy-HA as a coating material to enhance the stem cell response in tissue-engineering scaffolds. PMID:23621360

  1. Effects of Surface Modification on the Dispersion Property of VGCF

    Institute of Scientific and Technical Information of China (English)

    FU Yaqin; HAN Chunshao; NI Qingqing

    2009-01-01

    In view of the easy agglomeration issue of vapor grown carbon fiber (VGCF) and the poor interfacial adhesion between VGCF and matrix resin, two-step surface modification with hydrogen peroxide and concentrated nitric acid was performed on VGCF. The surface structure and dispersion of VGCF before and after modification were tested and analyzed by XRD, TGA, FTIR, UV-visible spectrum and SEM. Moreover, VGCF/SMPU composites were prepared via a solution mixing method taking shape memory polyurethane (SMPU) as matrix, and the mechanical properties of the composites were also tested. The graphite crystal structure of VGCF showed very little change af-ter modification, the concentration of oxygen-containing functional groups on the surface of VGCF was visibly in-creased, and the dispersion and dispersion stability of VGCF in organic solvent were also clearly improved. In the cross section of the VGCF/SMPU composites, the dispersion of VGCF in matrix and the VGCF-matrix interfacial adhesion observed through SEM were both enhanced to a certain extent after surface modification. The two-step surface modified VGCF had more obvious mechanical reinforcement effects on the composites than that of the pris-tine VGCF.

  2. Unravelling merging behaviors and electrostatic properties of CVD-grown monolayer MoS2 domains.

    Science.gov (United States)

    Hao, Song; Yang, Bingchu; Gao, Yongli

    2016-08-28

    The presence of grain boundaries is inevitable for chemical vapor deposition (CVD)-grown MoS2 domains owing to various merging behaviors, which greatly limits its potential applications in novel electronic and optoelectronic devices. It is therefore of great significance to unravel the merging behaviors of the synthesized polygon shape MoS2 domains. Here we provide systematic investigations of merging behaviors and electrostatic properties of CVD-grown polycrystalline MoS2 crystals by multiple means. Morphological results exhibit various polygon shape features, ascribed to polycrystalline crystals merged with triangle shape MoS2 single crystals. The thickness of triangle and polygon shape MoS2 crystals is identical manifested by Raman intensity and peak position mappings. Three merging behaviors are proposed to illustrate the formation mechanisms of observed various polygon shaped MoS2 crystals. The combined photoemission electron microscopy and kelvin probe force microscopy results reveal that the surface potential of perfect merged crystals is identical, which has an important implication for fabricating MoS2-based devices. PMID:27586938

  3. Flavin Derivatives with Tailored Redox Properties: Synthesis, Characterization, and Electrochemical Behavior.

    Science.gov (United States)

    Kormányos, Attila; Hossain, Mohammad S; Ghadimkhani, Ghazaleh; Johnson, Joe J; Janáky, Csaba; de Tacconi, Norma R; Foss, Frank W; Paz, Yaron; Rajeshwar, Krishnan

    2016-06-27

    This study establishes structure-property relationships for four synthetic flavin molecules as bioinspired redox mediators in electro- and photocatalysis applications. The studied flavin compounds were disubstituted with polar substituents at the N1 and N3 positions (alloxazine) or at the N3 and N10 positions (isoalloxazines). The electrochemical behavior of one such synthetic flavin analogue was examined in detail in aqueous solutions of varying pH in the range from 1 to 10. Cyclic voltammetry, used in conjunction with hydrodynamic (rotating disk electrode) voltammetry, showed quasi-reversible behavior consistent with freely diffusing molecules and an overall global 2e(-) , 2H(+) proton-coupled electron transfer scheme. UV/Vis spectroelectrochemical data was also employed to study the pH-dependent electrochemical behavior of this derivative. Substituent effects on the redox behavior were compared and contrasted for all the four compounds, and visualized within a scatter plot framework to afford comparison with prior knowledge on mostly natural flavins in aqueous media. Finally, a preliminary assessment of one of the synthetic flavins was performed of its electrocatalytic activity toward dioxygen reduction as a prelude to further (quantitative) studies of both freely diffusing and tethered molecules on various electrode surfaces. PMID:27243969

  4. Chain length dependence of non-surface activity and micellization behavior of cationic amphiphilic diblock copolymers.

    Science.gov (United States)

    Ghosh, Arjun; Yusa, Shin-ichi; Matsuoka, Hideki; Saruwatari, Yoshiyuki

    2014-04-01

    The cationic and anionic amphiphilic diblock copolymers with a critical chain length and block ratio do not adsorb at the air/water interface but form micelles in solution, which is a phenomenon called "non-surface activity". This is primarily due to the high charge density of the block copolymer, which creates a strong image charge effect at the air/water interface preventing adsorption. Very stable micelle formation in bulk solution could also play an important role in the non-surface activity. To further confirm these unique properties, we studied the adsorption and micellization behavior of cationic amphiphilic diblock copolymers of poly(n-butyl acrylate)-b-poly(3-(methacryloyloxy)ethyl)trimethylammonium chloride) (PBA-b-PDMC) with different molecular weights of hydrophobic blocks but with the same ionic block length. These block copolymers were successfully prepared via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerization. The block copolymer with the shortest hydrophobic block length was surface-active; the solution showed surface tension reduction and foam formation. However, above the critical block ratio, the surface tension of the solution did not decrease with increasing polymer concentration, and there was no foam formation, indicating lack of surface activity. After addition of 0.1 M NaCl, stable foam formation and slight reduction of surface tension were observed, which is reminiscent of the electrostatic nature of the non-surface activity. Fluorescence and dynamic and static light scattering measurements showed that the copolymer with the shortest hydrophobic block did not form micelles, while the block copolymers formed spherical micelles having radii of 25-30 nm. These observations indicate that micelle formation is also important for non-surface activity. Upon addition of NaCl, cmc did not decrease but rather increased as observed for non-surface-active block copolymers previously studied. The micelles formed were

  5. Bactericidal behavior of Cu-containing stainless steel surfaces

    Science.gov (United States)

    Zhang, Xiangyu; Huang, Xiaobo; Ma, Yong; Lin, Naiming; Fan, Ailan; Tang, Bin

    2012-10-01

    Stainless steels are one of the most common materials used in health care environments. However, the lack of antibacterial advantage has limited their use in practical application. In this paper, antibacterial stainless steel surfaces with different Cu contents have been prepared by plasma surface alloying technology (PSAT). The steel surface with Cu content 90 wt.% (Cu-SS) exhibits strong bactericidal activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 3 h. Although the Cu-containing surface with Cu content 2.5 wt.% (CuNi-SS) can also kill all tested bacteria, this process needs 12 h. SEM observation of the bacterial morphology and an agarose gel electrophoresis were performed to study the antibacterial mechanism of Cu-containing stainless steel surfaces against E. coli. The results indicated that Cu ions are released when the Cu-containing surfaces are in contact with bacterial and disrupt the cell membranes, killing the bacteria. The toxicity of Cu-alloyed surfaces does not cause damage to the bacterial DNA. These results provide a scientific explanation for the antimicrobial applications of Cu-containing stainless steel. The surfaces with different antibacterial abilities could be used as hygienic surfaces in healthcare-associated settings according to the diverse requirement of bactericidal activities.

  6. Investigation of CVD graphene topography and surface electrical properties

    International Nuclear Information System (INIS)

    Combining scanning probe microscopy techniques to characterize samples of graphene, a selfsupporting, single atomic layer hexagonal lattice of carbon atoms, provides far more information than a single technique can. Here we focus on graphene grown by chemical vapour deposition (CVD), grown by passing carbon containing gas over heated copper, which catalyses single atomic layer growth of graphene on its surface. To be useful for applications the graphene must be transferred onto other substrates. Following transfer it is important to characterize the CVD graphene. We combine atomic force microscopy (AFM) and scanning Kelvin probe microscopy (SKPM) to reveal several properties of the transferred film. AFM alone provides topographic information, showing ‘wrinkles’ where the transfer provided incomplete substrate attachment. SKPM measures the surface potential indicating regions with different electronic properties for example graphene layer number. By combining AFM and SKPM local defects and impurities can also be observed. Finally, Raman spectroscopy can confirm the structural properties of the graphene films, such as the number of layers and level of disorder, by observing the peaks present. We report example data on a number of CVD samples from different sources. (paper)

  7. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    Science.gov (United States)

    Issa, Bashar; Obaidat, Ihab M.; Albiss, Borhan A.; Haik, Yousef

    2013-01-01

    Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm), viruses, genes, down to proteins (3–50 nm). The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents. PMID:24232575

  8. Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

    Directory of Open Access Journals (Sweden)

    Bashar Issa

    2013-10-01

    Full Text Available Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm, viruses, genes, down to proteins (3–50 nm. The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents.

  9. Correlation between optical properties surface morphology of porous silicon electrodeposited by Fe3+ ion

    Science.gov (United States)

    Mabrouk, Asma; Lorrain, N.; Haji, M. L.; Oueslati, Meherzi

    2015-01-01

    In this paper, we analyze the photoluminescence spectra (PL) of porous silicon (PS) layer which is elaborated by electrochemical etching and passivated by Fe3+ ions (PSF) via current density, electro-deposition and temperature measurements. We observe unusual surface morphology of PSF surface and anomalous emission behavior. The PSF surface shows regular distribution of cracks, leaving isolated regions or 'platelets' of nearly uniform thickness. These cracks become more pronounced for high current densities. The temperature dependence of the PL peak energy (EPL) presents anomalous behaviors, i.e., the PL peak energy shows a successive red/blue/redshift (S-shaped behavior) with increasing temperature that we attribute to the existence of strong potential fluctuations induced by the electrochemical etching of PS layers. A competition process between localized and delocalized excitons is used to discuss these PL properties. In this case, the potential confinement plays a key role on the enhancement of PL intensity in PSF. To explain the temperature dependence of the PL intensity, we have proposed a recombination model based on the tunneling and dissociation of excitons.

  10. Effect of surface morphology on the oxidation behavior of bulk metallic glass

    International Nuclear Information System (INIS)

    Highlights: • The effect of surface morphology on the oxidation behavior of BMG is investigated. • It is the scratch sharpness, rather than the surface roughness, should account for the acceleration effect on BMG oxidation. • The acceleration mechanism of surface morphology on BMG oxidation is different from that on the oxidation of crystalline materials due to the difference of intrinsic microstructures. - Abstract: The effect of surface morphology on the oxidation behavior of a Zr55Cu30Al10Ni5 bulk metallic glass was investigated. The results revealed that specimens with rougher surfaces oxidized faster than specimens with smoother surfaces, resulting in larger and denser segregated particles, as well as thicker scales. The effect of surface morphology on the oxidation behavior was explained from the aspects of thermodynamics and diffusion kinetics. It was found that it is the scratch sharpness, rather than the roughness, should account for the acceleration effect on BMG, which is different from that of crystalline materials

  11. Properties and Mechanobiological Behavior of Bovine Nasal Septum Cartilage.

    Science.gov (United States)

    Correro-Shahgaldian, Maria Rita; Introvigne, Jasmin; Ghayor, Chafik; Weber, Franz E; Gallo, Luigi M; Colombo, Vera

    2016-05-01

    Bovine nasal septum (BNS) is a source of non-load bearing hyaline cartilage. Little information is available on its mechanical and biological properties. The aim of this work was to assess the characteristics of BNS cartilage and investigate its behavior in in vitro mechanobiological experiments. Mechanical tests, biochemical assays, and microscopic assessment were performed for tissue characterization. Compressions tests showed that the tissue is viscoelastic, although values of elastic moduli differ from the ones of other cartilaginous tissues. Water content was 78 ± 1.4%; glycosaminoglycans and collagen contents-measured by spectrophotometric assay and hydroxyproline assay-were 39 ± 5% and 25 ± 2.5% of dry weight, respectively. Goldner's Trichrome staining and transmission electron microscopy proved isotropic cells distribution and results of earlier cell division. Furthermore, gene expression was measured after uniaxial compression, showing variations depending on compression time as well as trends depending on equilibration time. In conclusion, BNS has been characterized at several levels, revealing that bovine nasal tissue is regionally homogeneous. Results suggest that, under certain conditions, BNS could be used to perform in vitro cartilage loading experiments. PMID:26502171

  12. Wetting behavior of nano-scale dual rough surfaces coated with hydrophobic DLC films

    International Nuclear Information System (INIS)

    Solid surface wettability can be controlled by chemical treatment of the material surface or modification of the surface topology. Superhydrophobic surfaces, having the water contact angle close to 180 degrees, have drawn much attention owing to its potential applications for water-repellent self cleaning surfaces, surface energy induced drop motion, and flow channels of low resistance for microfludics devices, etc. We showed earlier the superhydrophobic wetting behavior of a water droplet on nano-scale dual rough surfaces with hydrophobic DLC films. Here we report the results of systematic experiments of the evaporation of a water droplet on the superhydrophobic dual rough surfaces to measure the time evolution of the contact angle induced by the change of the Laplace pressure. The transition condition from Cassie-Baxter mode to Wenzel mode in the droplet wetting behavior was analyzed and compared with that of other superhydrophobic surfaces. The effectiveness and superhydrophobicity of the dual rough structure was also discussed

  13. Investigation of the surface adsorption and biotribological properties of mucins

    DEFF Research Database (Denmark)

    Madsen, Jan Busk

    Tribology is the study of friction, wear, adhesion and lubrication. Biotribology covers all aspects of tribology that are related to biological systems. Most organisms face tribological challenges where increased friction is often desirable, such as walking, gripping and lifting objects or adhering...... physical barrier that reduces adhesion to, and penetration of, the epithelial cell layer by bacteria. The composition of the mucin macromolecules includes hydrophobic globular terminal domains that are separated by heavily glycosylated (hydrophilic) central domains. The central domains carry an overall...... mucins and their aqueous lubrication properties have led to them being proposed as possible biocompatible lubricants. In this thesis, we investigate the biotribological properties of two commercially available mucins on the soft, elastomeric and hydrophobic surface of PDMS under different conditions. Due...

  14. Nanopatterned antimicrobial enzymatic surfaces combining biocidal and fouling release properties

    Science.gov (United States)

    Yu, Qian; Ista, Linnea K.; López, Gabriel P.

    2014-04-01

    Surfaces incorporating the antimicrobial enzyme, lysozyme, have been previously demonstrated to effectively disrupt bacterial cellular envelopes. As with any surface active antimicrobial, however, lysozyme-expressing surfaces become limited in their utility by the accumulation of dead bacteria and debris. Surfaces modified with environmentally responsive polymers, on the other hand, have been shown to reversibly attach and release both live and dead bacterial cells. In this work, we combine the antimicrobial activity of lysozyme with the fouling release capability of the thermally responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), which has a lower critical solution temperature (LCST) in water at ~32 °C. Nanopatterned PNIPAAm brushes were fabricated using interferometric lithography followed by surface-initiated polymerization. Lysozyme was then adsorbed into the polymer-free regions of the substrate between the brushes to achieve a hybrid surface with switchable antimicrobial activity and fouling-release ability in response to the change of temperature. The temperature triggered hydration and conformational change of the nanopatterned PNIPAAm brushes provide the ability to temporally regulate the spatial concealment and exposure of adsorbed lysozyme. The biocidal efficacy and release properties of the hybrid surface were tested against Escherichia coli K12 and Staphylococcus epidermidis. The hybrid surfaces facilitated the attachment of bacteria at 37 °C for E. coli and 25 °C for S. epidermidis and when the temperature is above the LCST, collapsed and dehydrated PNIPAAm chains expose lysozyme to kill attached bacteria. Changing temperature across the LCST of PNIPAAm (e.g. from 37 °C to 25 °C for E. coli or from 25 °C to 37 °C for S. epidermidis) to induce a hydration transition of PNIPAAm promoted the release of dead bacteria and debris from the surfaces upon mild shearing. These results suggest that nano-engineered surfaces can provide an effective

  15. Critical properties of the dynamical random surface with extrinsic curvature

    International Nuclear Information System (INIS)

    We analyze numerically the critical properties of a two-dimensional discretized random surface with extrinsic curvature embedded in a three-dimensional space. The use of the toroidal topology enables us to enforce the non-zero external extension without the necessity of defining a boundary and allows us to measure directly the string tension. We show that a most probably second-order phase transition from the crumpled phase to the smooth phase observed earlier for a spherical topology appears also for a toroidal surface for the same finite value of the coupling constant of the extrinsic curvature term. The phase transition is characterized by the vanishing of the string tension. We discuss the possible non-trivial continuum limit of the theory, when approaching the critical point. (orig.)

  16. Electrocatalytic activity and surface properties of tungsten bronzes

    International Nuclear Information System (INIS)

    The electrocatalytic activities of sodium tungsten bronzes, including high purity crystals, platinum doped crystals, and platinum plated crystals, have been measured for oxygen reduction in acid solution. In addition, a survey of the electrocatalytic activities and general electrochemical properties of other alkali tungsten bronzes, thalium tungsten bronze, and tungsten trioxide were investigated and compared to sodium tungsten bronze. All measurements were done on single crystals. Pure sodium tungsten bronzes and WO3 have a slight catalytic activity for oxygen reduction. The exchange current density is approximately 10-14 A/cm2. Doping the cubic sodium tungsten bronze with up to 800 ppM of platinum slightly increased the catalytic activity of the crystals, but the effect was noticeable only at very low current densities. Platinum preelectrolysis of the solution was shown to contaminate the crystal surface with significant amounts of platinum. For the platinum plated bronze crystals, no synergistic effect between the platinum and the bronze was observed for oxygen reduction. However, different platinum plating methods gave more than an order of magnitude difference in catalytic activity, with the same amount of platinum. The platinum was deposited on the bronze surface in different forms by the different plating methods. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO3. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO3. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible

  17. Electrocatalytic activity and surface properties of tungsten bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M.F.

    1977-12-01

    The electrocatalytic activities of sodium tungsten bronzes, including high purity crystals, platinum doped crystals, and platinum plated crystals, have been measured for oxygen reduction in acid solution. In addition, a survey of the electrocatalytic activities and general electrochemical properties of other alkali tungsten bronzes, thalium tungsten bronze, and tungsten trioxide were investigated and compared to sodium tungsten bronze. All measurements were done on single crystals. Pure sodium tungsten bronzes and WO/sub 3/ have a slight catalytic activity for oxygen reduction. The exchange current density is approximately 10/sup -14/ A/cm/sup 2/. Doping the cubic sodium tungsten bronze with up to 800 ppM of platinum slightly increased the catalytic activity of the crystals, but the effect was noticeable only at very low current densities. Platinum preelectrolysis of the solution was shown to contaminate the crystal surface with significant amounts of platinum. For the platinum plated bronze crystals, no synergistic effect between the platinum and the bronze was observed for oxygen reduction. However, different platinum plating methods gave more than an order of magnitude difference in catalytic activity, with the same amount of platinum. The platinum was deposited on the bronze surface in different forms by the different plating methods. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO/sub 3/. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible. One possible form of highly dispersed platinum on a bronze surface is the formation of a platinum tungsten bronze, Pt/sub x/WO/sub 3/. Hydrogen tungsten bronze is formed in the surface layers of all the bronzes at potentials below +0.2 V (NHE), and the reaction is completely reversible.

  18. Antibacterial properties of biomedical surfaces containing micrometric silver islands

    International Nuclear Information System (INIS)

    A set of Cu-Mn-O and Ag-Cu-Mn-O films were sputter-deposited onto polished Ti-6Al-4V coupons and the microbiological adherence of Staphylococcus sp. was studied in these biomedical surfaces modified using advanced ternary and quaternary oxides that incorporated micrometric silver islands. The as-deposited ternary and quaternary compounds were amorphous. Upon air annealing the Ag-Cu-Mn-O films, silver-oxygen bonds in the compound destabilize, resulting in the segregation of metallic silver in the form of micrometric layered silver islands with high specific area dispersed at the surface of the remaining oxide. Silver is well known to have a natural biocidal character and its presence in the surface forming large micrometric escalonated islands is, in principle, predicted to enhance the antimicrobial properties of biomedical surfaces. Microbial adhesion tests were performed in triplicates using collection strains of Staphylococcus aureus and Staphylococcus epidermidis. Preliminary results indicate that both strains showed decreased adherence to modified materials, S. epidermidis showed higher adherence these materials than S. aureus, however, there was no statistically significant differences between Cu-Mn-O and Ag-Cu-Mn-O containing silver islands.

  19. Tribological Properties of Nano-dimensional Systems Containing Carbon Surfaces

    Directory of Open Access Journals (Sweden)

    A.V. Khomenko

    2014-04-01

    Full Text Available We review tribological properties of boundary films of hydrocarbons and water confined between atomically smooth and rough surfaces. Both theory and experiment show that ultrathin film of liquid with thickness less than six molecular diameters restricted in small volumes is solid-like. Such a state is characterized by the decrease of mobility of molecules related to the increase of relaxation times and decrease of the diffusion coefficient. Additionally, quasidiscrete layers of molecules appear and in-plane ordering of the layers occurs. Atomic-scale roughness of the walls destroys the order of the molecules. We also describe experimental studies of friction of graphite at the atomic level. The experiments suggest a principal possibility of superlubricity for the tungsten tip of friction force microscope sheared on the surface of graphite. A possible explanation of this phenomenon consists in the existence of the graphite nanoflake attached to the tip. However, reliable confirmation of this hypothesis is absent in the literature. We also review methods of the graphene preparation through exfoliation of a graphite sample and formation of defects in graphene as a result of its irradiation by different particles. We describe the experimental method of measurement of friction of metallic nanoparticles sliding on the surface of graphite. We consider basic advantages of this approach compared to the known methods and friction duality in these systems. The review indicates the necessity of further comprehensive theoretical study of friction of metallic nanoparticles adsorbed on atomically smooth surfaces.

  20. Formation and properties of metallic nanoparticles on compound semiconductor surfaces

    Science.gov (United States)

    Kang, Myungkoo

    When electromagnetic radiation is incident upon metallic nanoparticles (NPs), a collective oscillation, termed a surface plasmon resonance (SPR), is generated. Recently, metallic NPs on semiconductor surfaces have enabled the generation of SPR, promising for enhanced light emission, efficient solar energy harvesting, biosensing, and metamaterials. Metallic NPs have been fabricated by focused ion beam (FIB) which has an advantage of cost-effectiveness over conventional lithography process requiring multi-step processes. Here, we report formation and properties of FIB-induced metallic NPs on compound semiconductor surfaces. Results presented in this thesis study suggest that FIB-induced Ga NPs can be a promising alternative plasmonic material. In particular, using a combined experimental-computational approach, we discovered a universal mechanism for ion-induced NP formation, which is governed by the sputtering yield of semiconductor surfaces. We also discovered a governing mechanism for ion-induced NP motion, which is driven by thermal fluctuation and anisotropic mass transport. Furthermore, we demonstrated Ga NP arrays with plasmon resonances with performance comparable to those of traditionally-used silver and gold NPs. We then finally demonstrated the Ga NP plasmoninduced enhancement of light emission from GaAs, which is the first ever combination of a new plasmonic material (Ga) and a new fabrication method (FIB) for the plasmon-enhanced light emission.

  1. Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

    Science.gov (United States)

    Schoop, Julius Malte

    Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is investigated as a substitutionary process for the current plastic infiltration process. Along with significant reductions in cycle time and resource use, surface quality of cryogenically machined un-infiltrated (as-sintered) porous tungsten has been shown to significantly outperform dry machining. The present study is focused on examining the relationship between machining parameters and cooling condition on the as-machined surface integrity of porous tungsten. The effects of cryogenic pre-cooling, rake angle, cutting speed, depth of cut and feed are all taken into consideration with respect to machining-induced surface morphology. Cermet and Polycrystalline diamond (PCD) cutting tools are used to develop high performance cryogenic machining of porous tungsten. Dry and pre-heated machining were investigated as a means to allow for ductile mode machining, yet severe tool-wear and undesirable smearing limited the feasibility of these approaches. By using modified PCD cutting tools, high speed machining of porous tungsten at cutting speeds up to 400 m/min is achieved for the first time. Beyond a critical speed, brittle fracture and built-up edge are eliminated as the result of a brittle to ductile transition. A model of critical chip thickness ( hc ) effects based on cutting

  2. Anomalous surface states modify the size-dependent mechanical properties and fracture of silica nanowires

    International Nuclear Information System (INIS)

    Molecular dynamics simulations of amorphous silica nanowires under tension were analyzed for size and surface stress effects on mechanical properties and for structural modifications via bond angle distributions. Their fracture behavior was also investigated beyond the elastic limit. The Young’s moduli of silica nanowires were predicted to be about 75–100 GPa, depending on the nanowire size. The ultimate strength was calculated to be ∼10 GPa, depending on the diameter, which is in excellent agreement with the experiments. The dependence of the Young’s modulus on nanowire diameter is explained in terms of surface compressive stress effects. The fracture behavior of nanowires was also found to be influenced by surface compressive stresses. Bond angle distribution analysis of various nanowires reveals significant compressive surface states, as evidenced by the appearance of a secondary peak in the Si-O-Si bond angle distribution at ∼97°, which is absent in bulk silica. The strain rate was found to have a negligible effect on the Young’s modulus of the silica nanowires, but it has a critical role in determining their fracture mode. (paper)

  3. Learning to behave: adaptive behavior for planetary surface rovers

    Science.gov (United States)

    Huntsberger, Terry; Aghazarian, Hrand

    2004-01-01

    Robotic missions to planetary surfaces are becoming more ambitious and of longer duration. The nominal mission timeline for the MER called Spirit currently on the Martian surface is 90 days, with extensions to 180 days depending on rover health. The upcoming 2009 MSL mission is planned to be 300-500 days and will possibly involve traverses on the order of a kilometer or more.

  4. Electronic properties of semiconductor surfaces and metal/semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tallarida, M.

    2005-05-15

    This thesis reports investigations of the electronic properties of a semiconductor surface (silicon carbide), a reactive metal/semiconductor interface (manganese/silicon) and a non-reactive metal/semiconductor interface (aluminum-magnesium alloy/silicon). The (2 x 1) reconstruction of the 6H-SiC(0001) surface has been obtained by cleaving the sample along the (0001) direction. This reconstruction has not been observed up to now for this compound, and has been compared with those of similar elemental semiconductors of the fourth group of the periodic table. This comparison has been carried out by making use of photoemission spectroscopy, analyzing the core level shifts of both Si 2p and C 1s core levels in terms of charge transfer between atoms of both elements and in different chemical environments. From this comparison, a difference between the reconstruction on the Si-terminated and the C-terminated surface was established, due to the ionic nature of the Si-C bond. The growth of manganese films on Si(111) in the 1-5 ML thickness range has been studied by means of LEED, STM and photoemission spectroscopy. By the complementary use of these surface science techniques, two different phases have been observed for two thickness regimes (<1 ML and >1 ML), which exhibit a different electronic character. The two reconstructions, the (1 x 1)-phase and the ({radical}3 x {radical}3)R30 -phase, are due to silicide formation, as observed in core level spectroscopy. The growth proceeds via island formation in the monolayer regime, while the thicker films show flat layers interrupted by deep holes. On the basis of STM investigations, this growth mode has been attributed to strain due to lattice mismatch between the substrate and the silicide. Co-deposition of Al and Mg onto a Si(111) substrate at low temperature (100K) resulted in the formation of thin alloy films. By varying the relative content of both elements, the thin films exhibited different electronic properties

  5. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Scott Leib

    2003-05-31

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, H{sub c} in cases 1, 3, and 5, and the uniaxial character of the Gd{sub 5}(Si{sub 2}Ge{sub 2}), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, M{sub s}, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected from theory and

  6. Ex vivo surface and mechanical properties of coated orthodontic archwires.

    Science.gov (United States)

    Elayyan, Firas; Silikas, Nick; Bearn, David

    2008-12-01

    This study examined the mechanical and physical properties of retrieved coated nickel-titanium (NiTi) archwires compared with unused samples. Ultraesthetic 0.016 inch coated archwires (G&H(R) Wire Company) were investigated. Ten as-received wires were subjected to a three-point bending test using conventional and self-ligating bracket systems. Surface roughness of the coating was measured with a contact stylus profilometer. Optical and scanning electron microscopes were used to assess surface topography. Ten archwires were used in vivo for a period of between 4 and 6 weeks. Retrieved archwires were subjected to the same tests. The percentage of the remaining coating was calculated using digital photography. Coated archwires were used in vivo for a mean period of 33 days. Differences between the mean values of the as-received and retrieved archwires were determined using t-tests. In the three-point bending test, with conventional elastomeric ligation, retrieved wires produced a lower unloading force (P self-ligating bracket system, retrieved and as-received coated archwires produced the same amount of force (P > 0.05). With surface profilometry, all measured roughness parameters (except R(sm)) had greater surface roughness for the retrieved coated archwires (P < 0.05). Under microscopy, retrieved coated archwires showed discolouration, ditching, and delamination. Only 75 per cent of the coating was present in retrieved coated archwires. Retrieved coated archwires produced lower unloading force values than as-received coated archwires with conventional ligation. Surface roughness of coated archwires increased after use. Coated archwires have a low aesthetic value, with 25 per cent of the coating lost within 33 days in vivo. PMID:19011166

  7. Enhancement of surface properties on commercial polymer packaging films using various surface treatment processes (fluorination and plasma)

    Energy Technology Data Exchange (ETDEWEB)

    Peyroux, Jérémy, E-mail: jeremy.peyroux@univ-bpclermont.fr [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Dubois, Marc, E-mail: marc.dubois@univ-bpclermont.fr [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Tomasella, Eric, E-mail: eric.tomasella@univ-bpclermont.fr [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Petit, Elodie, E-mail: elodie.petit@univ-bpclermont.fr [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, Institut de Chimie de Clermont-Ferrand, F-63171 Aubière (France); Flahaut, Delphine, E-mail: delphine.flahaut@univ-pau.fr [Université de Pau et des Pays de l’Adour, IPREM/ECP (UMR 5254), Hélioparc, 2 av. Pierre Angot, 64053 Pau cedex 9 (France)

    2014-10-01

    Graphical abstract: - Highlights: • Two different surface treatment processes were investigated in this work. • Both processes drastically change the composition induced on the surfaces. • Direct fluorination is identified as an efficient way to adjust surface properties. • Plasma processes result in a specific enhancement of the surface properties. • The pristine polymer surface has been successfully improved. - Abstract: Before considering their combination on commercial packaging films, two surface treatments processes were investigated. Indeed, direct fluorination and plasma processes are currently recognized as effective processes to improve polymer surface properties. The aim of this first work is to elucidate mechanisms that occur on the treated surface. The modifications of the surface layer were characterized using various complementary spectroscopy techniques such as Fourier Transform Infrared (FTIR) spectroscopy, high resolution solid state Nuclear Magnetic Resonance (NMR) with {sup 19}F nucleus which are suitable to determine the nature of bonding and specific groups formed during the process. X-ray Photoelectron Spectroscopy (XPS) was also achieved to extract the surface chemical compositions. In addition, surface properties of the treated films were studied by specific measurements of surface energy in order to reveal surface parameters such as rugosity and chemical composition which could be adjusted. All these results underline that the layer induced regardless of the two processes plays a key role in the enhancement of the surface properties.

  8. Enhancement of surface properties on commercial polymer packaging films using various surface treatment processes (fluorination and plasma)

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Two different surface treatment processes were investigated in this work. • Both processes drastically change the composition induced on the surfaces. • Direct fluorination is identified as an efficient way to adjust surface properties. • Plasma processes result in a specific enhancement of the surface properties. • The pristine polymer surface has been successfully improved. - Abstract: Before considering their combination on commercial packaging films, two surface treatments processes were investigated. Indeed, direct fluorination and plasma processes are currently recognized as effective processes to improve polymer surface properties. The aim of this first work is to elucidate mechanisms that occur on the treated surface. The modifications of the surface layer were characterized using various complementary spectroscopy techniques such as Fourier Transform Infrared (FTIR) spectroscopy, high resolution solid state Nuclear Magnetic Resonance (NMR) with 19F nucleus which are suitable to determine the nature of bonding and specific groups formed during the process. X-ray Photoelectron Spectroscopy (XPS) was also achieved to extract the surface chemical compositions. In addition, surface properties of the treated films were studied by specific measurements of surface energy in order to reveal surface parameters such as rugosity and chemical composition which could be adjusted. All these results underline that the layer induced regardless of the two processes plays a key role in the enhancement of the surface properties

  9. Mechanical Behavior of Free-Standing Fuel Cell Electrodes on Water Surface.

    Science.gov (United States)

    Kim, Sanwi; Kim, Jae-Han; Oh, Jong-Gil; Jang, Kyung-Lim; Jeong, Byeong-Heon; Hong, Bo Ki; Kim, Taek-Soo

    2016-06-22

    Fundamental understanding of the mechanical behavior of polymer electrolyte fuel cell electrodes as free-standing materials is essential to develop mechanically robust fuel cells. However, this has been a significant challenge due to critical difficulties, such as separating the pristine electrode from the substrate without damage and precisely measuring the mechanical properties of the very fragile and thin electrodes. We report the mechanical behavior of free-standing fuel cell electrodes on the water surface through adopting an innovative ice-assisted separation method to separate the electrode from decal transfer film. It is found that doubling the ionomer content in electrodes increases not only the tensile stress at the break and the Young's modulus (E) of the electrodes by approximately 2.1-3.5 and 1.7-2.4 times, respectively, but also the elongation at the break by approximately 1.5-1.7 times, which indicates that stronger, stiffer, and tougher electrodes are attained with increasing ionomer content, which have been of significant interest in materials research fields. The scaling law relationship between Young's modulus and density (ρ) has been unveiled as E ∼ ρ(1.6), and it is compared with other materials. These findings can be used to develop mechanically robust electrodes for fuel cell applications. PMID:27183314

  10. Theory of melt polyelectrolyte blends and block copolymers: Phase behavior, surface tension, and microphase periodicity

    Energy Technology Data Exchange (ETDEWEB)

    Sing, Charles E. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States); Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Zwanikken, Jos W.; Olvera de la Cruz, Monica [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-01-21

    Polymer mixtures such as blends or block copolymers are of great interest in energy applications and functional materials, and often, one or more of these species contain charges. The traditional fashion in which such materials are studied uses Self-Consistent Field Theory (SCFT) methods that incorporate electrostatics using Poisson-Boltzmann (PB) theory. We adapt a new and rigorous approach that does not rely on the mean-field assumptions inherent in the PB theory and instead uses Liquid State (LS) integral equation theory to articulate charge correlations that are completely neglected in PB. We use this theory to calculate phase diagrams for both blends and block copolyelectrolytes using SCFT-LS and demonstrate how their phase behavior is highly dependent on chain length, charge fraction, charge size, and the strength of Coulombic interactions. Beyond providing phase behavior of blends and block copolyelectrolytes, we can use this theory to investigate the interfacial properties such as surface tension and block copolyelectrolyte lamellar spacing. Lamellar spacing provides a way to directly compare the SCFT-LS theory to the results of experiments. SCFT-LS will provide conceptual and mathematical clarification of the role of charge correlations in these systems and aid in the design of materials based on charge polymers.

  11. Theory of melt polyelectrolyte blends and block copolymers: Phase behavior, surface tension, and microphase periodicity

    International Nuclear Information System (INIS)

    Polymer mixtures such as blends or block copolymers are of great interest in energy applications and functional materials, and often, one or more of these species contain charges. The traditional fashion in which such materials are studied uses Self-Consistent Field Theory (SCFT) methods that incorporate electrostatics using Poisson-Boltzmann (PB) theory. We adapt a new and rigorous approach that does not rely on the mean-field assumptions inherent in the PB theory and instead uses Liquid State (LS) integral equation theory to articulate charge correlations that are completely neglected in PB. We use this theory to calculate phase diagrams for both blends and block copolyelectrolytes using SCFT-LS and demonstrate how their phase behavior is highly dependent on chain length, charge fraction, charge size, and the strength of Coulombic interactions. Beyond providing phase behavior of blends and block copolyelectrolytes, we can use this theory to investigate the interfacial properties such as surface tension and block copolyelectrolyte lamellar spacing. Lamellar spacing provides a way to directly compare the SCFT-LS theory to the results of experiments. SCFT-LS will provide conceptual and mathematical clarification of the role of charge correlations in these systems and aid in the design of materials based on charge polymers

  12. 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.

  13. Study of tin oxide: Surface properties and palladium adsorption

    Science.gov (United States)

    Katsiev, Khabiboulakh

    Surface properties of various single-crystalline SnO2 surfaces were studied and the growth of palladium was investigated in the low-coverage regime. Metal - oxide structures play an important role in microelectronics and nanotechnology. They are also widely used in catalysis. Small catalytically-active metal particles on metal oxide substrates are key features in the gas sensing mechanism: they dramatically increase the sensitivity and selectivity of solid-state gas sensors towards target gases. Tin Oxide is widely used in solid-state gas sensors for detection of combustible and toxic gases. Its sensitivity and selectivity strongly depends on catalytic dopants, such as Pd or Pt, on the surface of the material. Thus, the characterization of Pd growth on tin oxide may give new insights into the catalytic and gas sensing mechanisms, and also help to understand fundamental steps that lead to various metal-on-oxide growth modes. Upon deposition of Pd onto the reduced (101) surface of a SnO2 single crystal, 1D cluster growth was observed. Starting from very low coverages, one-dimensional Pd clusters grow on the terraces, which indicates that the Pd wets the reduced tin oxide surface. Pd deposition on the oxidized surface results in randomly distributed three-dimensional Pd clusters. The clusters are distributed at step edges and on terraces without any apparent preferential adsorption sites. The one-dimensional clusters are imaged in scanning tunneling microscopy (STM) as straight, parallel nanostructures oriented along the [-101] direction, all with the same characteristic width of 0.5 nm and a height of 1 monolayer (ML). X-ray photoelectron spectroscopy (XPS) experiments show no sign of Pd oxidation; i.e. Pd grows as a metal. There is a 0.5 eV shift in the Pd 3d 5/2 core level peak position to lower binding energy that occurs during the initial stages of the growth on the reduced surface. This is an indication of charge transfer from the Pd clusters to the substrate

  14. Surface modification, microstructure and mechanical properties of investment cast superalloy

    Directory of Open Access Journals (Sweden)

    M. Zielińska

    2009-07-01

    Full Text Available Purpose: The aim of this work is to determine physical and chemical properties of cobalt aluminate (CoAl2O4 modifiers produced by different companies and the influence of different types of modifiers on the grain size, the microstructure and mechanical properties of high temperature creep resisting superalloy René 77.Design/methodology/approach: The first stage of the research work took over the investigations of physical and chemical properties of cobalt aluminate manufactured by three different companies: Remet, Mason Color and Permedia Lublin. There were determined the grain size distribution of cobalt aluminate powder, the average diameter of the powder particles, phase composition, cobalt contamination. In the next step, the ceramic moulds were made with different kind of cobalt aluminate (Mason Color, Remet, Permedia Lublin and its concentration (0.5% in the primary slurry. The samples of stepped and cylindrical shape were poured in the ceramic moulds prepared earlier. The average grain size of the γ phase, was determined on the stepped samples. The microstructure investigations let to examine the influence of the surface modification on the morphology of γ ‘ - phase and carbides precipitations. Samples were turned from cylindrical castings for mechanical properties investigations: creep tests.Findings: Modification of the face coat of ceramic mould results in the reduction of the grains size of γ matrix and disintegration of carbide precipitates. It results in the improvement of mechanical properties of the alloy. On the grounds of the obtained results, it was found that the type of used modifier influenced the grain size of the alloy and its mechanical properties.Research limitations/implications: The established physical and chemical properties of modifier let to get better control of grain size of the castings and their quality what will result in decrease of defective products.Originality/value: It was proved that the

  15. Vacuum chamber surface electronic properties influencing electron cloud phenomena

    International Nuclear Information System (INIS)

    In the vacuum science community, it is now commonly accepted that, for the present and next generation of accelerators, the surface electronic properties of the vacuum chamber material have to be studied in detail. Moreover, such studies are of valuable help to define the cleaning procedures of the chosen materials and to identify the most efficient vacuum commissioning. In the case of the large hadron collider (LHC) the proton beam stability, in the presence of an electron cloud, is analysed using beam induced electron multipacting (BIEM) simulations requiring a number of surface related properties, such as photon reflectivity, electron and photon induced electron emission, heat load, etc. and their modification during machine commissioning and operation. Such simulation codes base their validity on the completeness and reliability of the aforementioned input data. In this work we describe how a surface science approach has been applied to measure, total electron yield (SEY) as well as energy distribution curves excited by a very low-energy electron beam (0-320 eV), from the industrially prepared Cu co-laminated material, the adopted LHC beam-screen material, held at cryogenic temperatures (about 9 K). The data show that the SEY converges to unity at zero primary electron energy and that the ratio of reflected to secondary electrons increases for decreasing energy below about 70 eV, and becomes dominant below electron energies of about 20 eV. These observations lead to the notion of long-lived low-energy electrons in the accelerator vacuum chamber, which could be an issue for the LHC, damping rings and future accelerators

  16. Surface Properties of Cell-treated Polyethylene Terephthalate

    Directory of Open Access Journals (Sweden)

    Bing Shi

    2006-01-01

    Full Text Available The materials used in artificial joints undergo degradation through fatigue and corrosive wear in human body. The lifetime for well-designed artificial joints like hip joints is at most 12 years and a patient will usually have two total joint replacements during his/her lifetime. Tissue engineering, an alternative to total joint implantation, is the replacement of damaged tissue with the tissue that is designed and constructed to meet the needs of the individual patient. In this study, polyethylene terephthalate (PET in the form of overhead transparency films were investigated on their cell interactions and the tribological properties as an alternative tissue-engineering matrix. The base material of the transparency films is PET. Cell culture methods as well as atomic force microscope (AFM, contact angle goniometer, confocal microscope and universal tribotester were used to study the properties of the substrate materials and the interactions between the surface and the substrate materials. Results showed that cells grew on the substrate of the base materials of the PET. The tribological properties of the slides have been changed after being cell-treated.

  17. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Alfred Tcherbi-Narteh

    2013-01-01

    Full Text Available Diglycidyl ether of Bisphenol A (DGEBA based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.

  18. Effects of Surface Treatments of Montmorillonite Nanoclay on Cure Behavior of Diglycidyl Ether of Bisphenol A Epoxy Resin

    International Nuclear Information System (INIS)

    Diglycidyl ether of Bisphenol A (DGEBA) based SC-15 epoxy resin was modified with three different commercially available montmorillonite (MMT) nanoclay: Nanomer I.28E and Cloisite 10A and 30B. Cure behavior of nanocomposites was studied using a variety of techniques. Primary focus of this study was to investigate influence of different surface modifications of MMT nanoclay on rheological properties and cure behavior of SC-15 epoxy resin. By adding MMT to SC-15 epoxy resin, chemistry of the epoxy is altered leading to changes in rheological properties and ultimately enthalpy and activation energy of reactions. Addition of Nanomer I.28E delayed gelation, while Cloisite 10A and 30B accelerated gelation, regardless of the curing temperature. Activation energy of reaction was lower with the addition of Nanomer I.28E and Cloisite 10A and higher for Cloisite 30B compared to neat SC-15 epoxy composite.

  19. Chemical composition and surface charge properties of montmorillonite

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-wen; HU Min; HU Yue-hua

    2008-01-01

    The effects of the cell parameter and chemical composition on the surface charge properties of five kinds of different colour montmorillonites were studied. The results indicate that the surface isoelectric point(IEP) of the montmorillonite shows positive correlation with the mass fractions of Fe2O3 and K20, but it has little relation to the mass fractions of other chemical compositions. At around pH=6.8, the surface zeta potential of the montmorillonite shows the negative relationship with the mass fractions of Fe2O3 and MgO, but it does not linearly correlate to the mass fractions of other chemical compositions. Cell parameter(b0) of the montmofillonite expresses negative linear relationship with mass fractions of K2O and Na2O, so does c0sinβ with mass fractions of SiO2 and Fe2O3. And there is no specific relationship between bo and IEP of different montmori Uonites, but there is positive correlation between c0sinβ and IEP of different montmorillonite samples.

  20. Structure, mechanical properties and friction behavior of UHMWPE/HDPE/carbon nanofibers

    International Nuclear Information System (INIS)

    Effects of untreated and pretreated carbon nanofibers (CNFs) on the crystallization behavior, friction behavior, and mechanical properties of ultra high molecular weight polyethylene (UHMWPE)/high density polyethylene (HDPE) nanocomposites prepared by a twin-screw extrusion were studied. The differential scanning calorimetry and wide angle X-ray diffraction measurements indicated that the addition of CNFs impacted the temperature of crystallization, but had no significant effects on the crystalline structure of the UHMWPE/HDPE blend. The degree of crystallinity, and the tensile strength and modulus of the UHMWPE/HDPE systems exhibited an increasing trend initially with addition of CNFs, followed by a decrease at higher contents. With the increase of untreated CNF content, the friction coefficient of UHMWPE/HDPE was decreasing and displayed less change in the process of friction. The microstructure features on the fracture surfaces and friction surfaces of the polymer blend and the nanocomposites were analyzed in detail by scanning electron microscope observations. The degree of crystallinity of the nanocomposites with the pretreated CNFs exhibited a decrease due to the better interface adhesion compared to that in the nanocomposites with the same loading untreated CNFs. The enhancement in tensile strength of nanocomposites containing 0.5 wt% treated CNFs was four times higher (32%) than that of the nanocomposites containing untreated CNFs (8%) over that of the pure polymer

  1. Anticoagulation and endothelial cell behaviors of heparin-loaded graphene oxide coating on titanium surface.

    Science.gov (United States)

    Pan, Chang-Jiang; Pang, Li-Qun; Gao, Fei; Wang, Ya-Nan; Liu, Tao; Ye, Wei; Hou, Yan-Hua

    2016-06-01

    Owing to its unique physical and chemical properties, graphene oxide (GO) has attracted tremendous interest in many fields including biomaterials and biomedicine. The purpose of the present study is to investigate the endothelial cell behaviors and anticoagulation of heparin-loaded GO coating on the titanium surface. To this end, the titanium surface was firstly covered by the polydopamine coating followed by the deposition of the GO coating. Heparin was finally loaded on the GO coating to improve the blood compatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) indicated that the heparin-loaded GO coating was successfully created on the titanium surface. The scanning electron microscopy (SEM) images indicated that a relative uniform GO coating consisting of multilayer GO sheets was formed on the substrate. The hydrophilicity of the titanium surface was enhanced after the deposition of GO and further improved significantly by the loading heparin. The GO coating can enhance the endothelial cell adhesion and proliferation as compared with polydopamine coating and the blank titanium. Loading heparin on the GO coating can significantly reduce the platelet adhesion and prolong the activated partial thromboplastin time (APTT) while not influence the endothelial cell adhesion and proliferation. Therefore, the heparin-loaded GO coating can simultaneously enhance the cytocompatibility to endothelial cells and blood compatibility of biomaterials. Because the polydopamine coating can be easily prepared on most of biomaterials including polymer, ceramics and metal, thus the approach of the present study may open up a new window of promising an effective and efficient way to promote endothelialization and improve the blood compatibility of blood-contact biomedical devices such as intravascular stents. PMID:27040227

  2. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yucheng [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Xiao, Chengwen, E-mail: emoryxiao@163.com [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Wang, Xu; Yue, Jiajia; Zhu, Qiang [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2015-06-15

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile.

  3. Tensile properties and fracturing behavior of weld joints in the CLAM at high temperatures

    International Nuclear Information System (INIS)

    Highlights: • We use the stress triaxiality theory to explain the plastic deformation and facture behavior of the joints during the short term tensile tests at high temperature. • The tensile strength of CLAM welded joint at high temperature is lower compared with that at room temperature. • We explained the formation of crack and the reason of fracture. - Abstract: The tensile properties and fracturing behavior of weld joints in the Chinese low activation martensitic steel (CLAM) at high temperatures were studied. The result revealed that the cracks of weld joints in the base metal would appear in the heat-affected zone, after post-weld heat treatment for the high-temperature tensile test. The microstructure in the fractured frontier had different deformation and directions, and the fractured surface had different angles, a result associating with the normal faulting and shear fracturing. The tri-axial theory of stress can well explain the deformation and fracturing behavior of weld joints in the high-temperature tensile

  4. Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: application to Gusev Crater and Meridiani Planum

    OpenAIRE

    Fernando, J.; Schmidt, F.; Pilorget, C.; Pinet, P.; X. Ceamanos; Douté, S.; Daydou, Y.; Costard, F.

    2014-01-01

    The analysis of the surface texture from the particle (grain size, shape and internal structure) to its organization (surface roughness) provides information on the geological processes. CRISM multi-angular observations (varied emission angles) allow to characterize the surface scattering behavior which depends on the composition but also the material physical properties (e.g., grain size, shape, internal structure, the surface roughness). After an atmospheric correction by the Multi-angle Ap...

  5. Influence of Different Surface Treatments of H13 Hot Work Die Steel on Its Thermal Fatigue Behaviors

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Thermal fatigue checking is the general failure of hot work die steels, which is relative with the structures and properties of the steels and the stress alternated during the employment. The Uddeholm test method on thermal fatigue is used to compare the behaviors of different samples, which are treated with plasma nitriding、plasma sulfur-carbon-nitriding、 boronizing or not treated. The results show that the nitriding improves the thermal fatigue property of the tool steel, while the plasma sulfur-carbon-nitriding and the boronizing impair the property. The mechanisms are induced as follows. By increasing the hardness and changing the stress distribution in the surface layer, surface treatment can decrease the plastic deformation and the tensile stress during the cycling. Therefore,the generation and growth of the cracks are restrained. On the other hand, as results of surface treating, in the surface layer the toughness declines and the expanding coefficient ascendes; the latter change caused the strengthening of the tensile and compressive stress during the cycling. Thus the resistance to thermal fatigue is weakened. Whether or not the surface treatment is favor to thermal fatigue of tool steels relies on which factor is dominant.

  6. EFFECTS OF BLENDING CHITOSAN WITH PEG ON SURFACE MORPHOLOGY,CRYSTALLIZATION AND THERMAL PROPERTIES

    Institute of Scientific and Technical Information of China (English)

    Ling-hao He; Rui Xue; De-bin Yang; Ying Liu; Rui Song

    2009-01-01

    Biodegradable blend films composed of chitosan and PEG with various composition ratios were prepared. The chemical structure of the blend films was characterized with FTIR and X-ray, which showed no chemical bond formations but certain interactions probably coming from the hydrogen bonds. Morphologies of these blend films were viewed using AFM and SEM, suggesting that pure chitosan film had a smooth surface structure and the blend films surface showed a plenty of holes with varying size. Through the DMA measurement, it was found that there existed differences in the peak area and position of the blend films, and the peak at the glass transition temperature became significantly weaker and was markedly wider with the increasing content of PEG. The obtained results showed that the crystallinity of chitosan was suppressed and partially destroyed; and this should have an influence on the thermal behaviors and dynamic mechanical properties of the blend films.

  7. Corrosion properties of sealing surface material for RPV under abnormal working conditions

    International Nuclear Information System (INIS)

    Based on the corrosion issue of sealing surface material for RPV in some nuclear projects, the corrosion properties of sealing surface material for RPV under abnormal working conditions were investigated. The corrosion behavior of 308L stainless steel were studied by using autoclave in different contents of Cl- solutions, and these samples were observed and analyzed by means of the metalloscope and Scanning electron microscope (SEM). Results show that no pitting, crevice and stress corrosion occurred, when the content of Cl- was lower than 1 mg/L at the temperatures of 270℃ and the pressure of 5.5 MPa. However, with the increase of the content of Cl-, the susceptibility to pitting, crevice and stress corrosion of 308L was enhanced remarkably. (authors)

  8. SURFACE MODIFICATION OF TITANIUM FILMS WITH SODIUM ION IMPLANTATION: SURFACE PROPERTIES AND PROTEIN ADSORPTION

    Institute of Scientific and Technical Information of China (English)

    K. Y. Cai

    2007-01-01

    Sodium implanted titanium films with different ion doses were characterized to correlate their ion implantation parameters. Native titanium films and ion implanted titanium films were characterized with combined techniques of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and light microscopy (LM). The surface presented increased sodium concentration on treated titanium films with ion dose increasing, except for the group with the highest ion dose of 4× 1017 ions/cm2. XPS depth profiling displayed that sodium entered titanium film around 25-50 nm depth depending on its implantation ion dose. AFM characterization showed that sodium ion implantation treatment changed the surface morphology from a relatively smooth titanium film to rough surfaces corresponding to different implantation doses.After sodium implantation, implanted titanium films presented big particles with island structure morphology. The surface morphology and particle growth displayed the corresponding trend.Fibrinogen adsorption on these titanium films was performed to correlate with the surface properties of treated titanium films. The results show that protein adsorption on ion-implanted samples with dose of 2 × 1017 and 4 × 1017 are statistically higher (p < 0. 01) than samples treated with dose of 5×1016 and 1 ×1017, as well as the control samples.

  9. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    International Nuclear Information System (INIS)

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed

  10. Fracture behavior of circumferentially surface-cracked elbows. Technical report, October 1993--March 1996

    Energy Technology Data Exchange (ETDEWEB)

    Kilinski, T.; Mohan, R.; Rudland, D.; Fleming, M. [and others

    1996-12-01

    This report presents the results from Task 2 of the Second International Piping Integrity Research Group (IPIRG-2) program. The focus of the Task 2 work was directed towards furthering the understanding of the fracture behavior of long-radius elbows. This was accomplished through a combined analytical and experimental program. J-estimation schemes were developed for both axial and circumferential surface cracks in elbows. Large-scale, quasi-static and dynamic, pipe-system, elbow fracture experiments under combined pressure and bending loads were performed on elbows containing an internal surface crack at the extrados. In conjunction with the elbow experiments, material property data were developed for the A106-90 carbon steel and WP304L stainless steel elbow materials investigated. A comparison of the experimental data with the maximum stress predictions using existing straight pipe fracture prediction analysis methods, and elbow fracture prediction methods developed in this program was performed. This analysis was directed at addressing the concerns regarding the validity of using analysis predictions developed for straight pipe to predict the fracture stresses of cracked elbows. Finally, a simplified fitting flaw acceptance criteria incorporating ASME B2 stress indices and straight pipe, circumferential-crack analysis was developed.

  11. SURFACE STRUCTURE AND BULK PROPERTIES OF FLUORINATED POLY(ETHER URETHANE)S AND POLY(ETHER URETHANE) BLENDS

    Institute of Scientific and Technical Information of China (English)

    Hong Tan; Min Guo; Rong-ni Du; Xing-yi Xie; Jie-hua Li; Yin-ping Zhong; Qiang Fu

    2004-01-01

    It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.

  12. Influence of the biological conditions in the surface magnetic properties of nanocrystalline CoFeCrSiB ribbons

    International Nuclear Information System (INIS)

    In this paper the result of a study of the influence of the biological conditions on the surface magnetic properties of nanocrystalline Co64.5Fe2.5Cr3B15Si15 ribbons are presented and discussed. After the biological treatment the results show that, in the longitudinal direction, there is a hardening of the magnetic behavior and in the transverse direction the magnetization takes place in two steps. The surface saturation magnetization decreases in the treated samples. These results are explained considering the presence of magnetic oxides and non-conducting oxides on the surface of the treated samples

  13. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    Science.gov (United States)

    Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-01

    An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  14. NOAA Climate Data Record (CDR) of Ocean Near Surface Atmospheric Properties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Ocean Surface Bundle (OSB) Climate Data Record (CDR) consist of three parts: sea surface temperature, near-surface atmospheric properties, and heat fluxes....

  15. Structure and optical properties of water covered Cu(110) surfaces

    International Nuclear Information System (INIS)

    In this thesis structural and optical properties of the water covered Cu(110) surface is studied using density functional theory within independent particle approximation. Several stable adsorption structures are studied such as water clusters (monomer, dimer, trimer, tetramer and pentamer), different hexagonal monolayers, partially dissociated water monolayers and three different types of chains among them a chain that consists of pentagon rings. For a copper surface in contact with water vapor, the energetically stable H2O/OH adsorbed structures are compared thermodynamically using adsorption free energy (change of free energy due to adsorption). Several phase diagrams with respect to temperature and pressure are calculated. It is found that among the large number of energetically stable structures (i.e. structures with positive adsorption energy ) only limited number of them are thermodynamically stable. These thermodynamically stable structures are the class of almost energetically degenerate hexagonal overlayers, one type of partially dissociated water structure that contains Bjerrum defect in the hydrogen bond network and pentagon chain. Since hydrogen atoms are light weight their vibrational effects can be considerable. Zero point vibration decreases the adsorption energy up to 0.1 eV and free energy of adsorbed molecules arising from vibrational degree of freedom can go up to -0.2 eV per adsorbed molecule at 500 Kelvin. However zero point energy and vibrational free energy of adsorbed molecules do not alter relative stability of the adsorbed structures. To account for the long range van der Waals interactions, a semi-empirical scheme is applied. Reflectance Anisotropy Spectroscopy (RAS) is a fast and non destructive optical method that can be used to prob the surface in different conditions such as vacuum and electro-chemical environment. Elasto-optic coeficients of bulk are calculated from first principles and the change of the RA spectrum of the bare Cu

  16. In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

    Institute of Scientific and Technical Information of China (English)

    戴翌龙; 余琨; 陈良建; 陈畅; 乔雪岩; 颜阳

    2015-01-01

    Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope (SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low pH values in simulated body fluid (SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.

  17. Modeling mechanical behaviors of composites with various ratios of matrixeinclusion properties using movable cellular automaton method

    Institute of Scientific and Technical Information of China (English)

    A.Yu. SMOLIN; E.V. SHILKO; S.V. ASTAFUROV; I.S. KONOVALENKO; S.P. BUYAKOVA; S.G. PSAKHIE

    2015-01-01

    Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is used for modeling the mechanical behaviors of such different heterogeneous materials. The method is based on particle approach and may be considered as a kind of discrete element method. The main feature of the method is the use of many-body forces of inter-element interaction within the formalism of simply deformable element approximation. It was shown that the strength of reinforcing particles and the width of particle-binder interphase boundaries had determining influence on the service characteristics of metaleceramic composite. In particular, the increasing of strength of carbide inclusions may lead to significant increase in the strength and ultimate strain of composite material. On the example of porous zirconia ceramics it was shown that the change in the mechanical properties of pore surface leads to the corresponding change in effective elastic modulus and strength limit of the ceramic sample. The less is the pore size, the more is this effect. The increase in the elastic properties of pore surface of ceramics may reduce its fracture energy.

  18. Surface roughness of an asphalt concrete and its mechanical behavior

    OpenAIRE

    MOMM, L; DE LA ROCHE, C; Domingues, A.

    2003-01-01

    The surface roughness of asphalt concrete is studied according to the maximum aggregate size and to the equation of the aggregate graduation curve, on asphalt concrete plates made in laboratory. The macrotexture increases when the maximum aggregate size increases and it decreases when the aggregate fine contents increases. The asphalt concrete structural behaviour is evaluated with rutting, complex modulus and fatigue tests. The study shows stronger mechanical performances on the asphalt conc...

  19. Effects of sputtering conditions on electrochemical behavior and physical properties of Ni-Mo alloy electrode

    Institute of Scientific and Technical Information of China (English)

    HUANG Jin-zhao; XU Zheng; LI Hai-ling; KANG Guo-hu; WANG Wen-jing

    2006-01-01

    Sputtering method was used to prepare Ni-Mo alloy electrodes for hydrogen production in alkaline solution. The influences of the working pressure during deposition and the substrate temperature on the electrochemical behavior of electrode were characterized by steady-state polarization plot and Tafel polarization curve measurements. And the physical properties of electrodes were characterized by XRD, SEM, AFM and EDS. It is found that the overpotential is significantly influenced by the working pressure which affects critically the electrode surface morphology, and two Tafel regions are observed for each sample. The overpotential value does not change very much with the substrate temperature. The XRD results indicates that the electrodes should be considered nanocrystalline. Thornton model for the microstructure of sputter-deposited electrodes is referred to explain the observed microstructure change.

  20. Optical properties of diamond-machined metal surfaces and their relationship to physical and chemical surface perfection

    International Nuclear Information System (INIS)

    It has been demonstrated that copper and other metal surfaces can be diamond single point machined (DSPM) to a surface quality which will result in nearly intrinsic optical properties. Especially interesting is the observation of the interrelationship of laser induced melt and slip thresholds for DSPM copper for different surface preparation methods. Particularly important parameters are the machining fluid and the tool geometry. Both of these factors influence the degree of cold work introduced into the surface. In a companion paper at this conference, the nature of the surface damage is correlated with machining conditions. In this paper, the same surfaces are described optically. Significant variation in optical and mechanical properties can be demonstrated. The ability to change the characteristics including laser damage properties of the machined surface can be used in some cases to advantage, to actually tailor the surface to the requirements of a specific application

  1. Surface Nb-ALLOYING on 0.4C-13Cr Stainless Steel: Microstructure and Tribological Behavior

    Science.gov (United States)

    Yu, Shengwang; You, Kai; Liu, Xiaozhen; Zhang, Yihui; Wang, Zhenxia; Liu, Xiaoping

    2016-02-01

    0.4C-13Cr stainless steel was alloyed with niobium using double glow plasma surface alloying and tribological properties of Nb-alloyed steel such as hardness, friction and wear were measured. Effects of the alloying temperature on microstructure and the tribological behavior of the alloyed steel were investigated compared with untreated steel. Formation mechanisms of Nb-alloyed layers and increased wear resistance were also studied. The result shows that after surface Nb-alloying treatment, the 0.4C-13Cr steel exhibits a diffusion adhesion at the alloyed layer/substrate interface and improved tribological property. The friction coefficient of Nb-alloyed steel is decreased by about 0.3-0.45 and the wear rate after Nb-alloying is only 2-5% of untreated steel.

  2. Nanomechanical properties of a Ni nanodot-patterned surface

    International Nuclear Information System (INIS)

    Nanomechanical properties of a Ni nanodot-patterned surface (NDPS) on a Si substrate were investigated using nanoindentation. The Ni NDPS was fabricated by thermal evaporation of Ni through a porous anodized aluminum oxide template onto a Si substrate. Plan-view transmission electron microscopy and nanobeam diffraction were used to characterize the Ni nanodot crystal structure. Scanning electron microscopy and atomic force microscopy were used to characterize the morphology and deformation of the Ni nanodots before and after nanoindentation. The elastic modulus and hardness of the Ni nanodots were found to be 159 ± 22 and 7.7 ± 1.0 GPa, respectively. The critical shear stress for initiating plastic deformation in the Ni nanodot was estimated to be 8.3 ± 1.0 GPa, which is close to the theoretical shear strength of 7.6 GPa in dislocation-free single crystal Ni

  3. Catalytic behaviour and surface properties of supported lanthana

    Energy Technology Data Exchange (ETDEWEB)

    Castiglioni, J.; Kieffer, R. (Lab. de Chimie Organique Appliquee, EHICS, 67 - Strasbourg (France)); Botana, F.J.; Calvino, J.J.; Rodriguez-Izquierdo, J.M.; Vidal, H. (Dept. de Quimica Inorganica, Univ. de Cadiz, Puerto Real (Spain))

    1992-03-25

    This paper deals with the role of dispersed lanthana as an active phase in several catalytic reactions: CO hydrogenation, CO oxidation, and oxidative dimerization of methane. Characterization of the prepared catalysts indicates that lanthana can be effectively dispersed on silica and on ceria. While in the case of silica-supported catalysts lanthana appears at the surface, leading to an almost full coverage for loadings higher than 40%, in the case of ceria-based systems, lanthana forms a solid solution with the support. In all the reactions studied, the presence of lanthana can be related to significant changes in the catalytic properties of the bare supports. Thus, the selectivity towards the total oxidation products observed on pure ceria is decreased, and the low activity shown by silica is enhanced. For the CO + H{sub 2} reaction, the addition of lanthana also generates upgraded products. (orig.).

  4. Correlation between surface properties and wettability of multi-scale structured biocompatible surfaces

    Science.gov (United States)

    Gorodzha, S. N.; Surmeneva, M. A.; Prymak, O.; Wittmar, A.; Ulbricht, M.; Epple, M.; Teresov, A.; Koval, N.; Surmenev, R. A.

    2015-11-01

    The influence of surface properties of radio-frequency (RF) magnetron deposited hydroxyapatite (HA) and Si-containing HA coatings on wettability was studied. The composition and morphology of the coatings fabricated on titanium (Ti) were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface wettability was studied using contact angle analysis. Different geometric parameters of acid-etched (AE) and pulse electron beam (PEB)-treated Ti substrates and silicate content in the HA films resulted in the different morphology of the coatings at micro- and nano- length scales. Water contact angles for the HA coated Ti samples were evaluated as a combined effect of micro roughness of the substrate and nano-roughness of the HA films resulting in higher water contact angles compared with acid-etched (AE) or pulse electron beam (PEB) treated Ti substrates.

  5. Synthesis and surface properties of a pH-regulated and pH-reversible anionic gemini surfactant.

    Science.gov (United States)

    Lv, Jing; Qiao, Weihong; Xiong, Chongqiao

    2014-07-22

    A new series of N,N'-dialkyl-N,N'-diacetate ethylenediamine, differing by the length of the carbon tails (8, 10, and 12), was synthesized in two steps. Their surface properties and aggregation behavior were studied in aqueous solution using pH titration, surface tension, zeta potential, dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescence measurements. On the basis of the pKa values obtained, surface tension was measured, as well as key surface property parameters. Combined with the zeta potential and DLS results, the experiments produced vesicles and reflected their pH-controllability through subsequent TEM and fluorescence measurements. pH-switchability was found to be reversible by light transmittance. Emulsion stability of dodecane-in-water in different pH showed that emulsion type was reversed between "on" for the O/W emulsion type and "off" for the W/O. PMID:24972329

  6. Mapping surface properties of sinusoidal roughness standards by TPM

    International Nuclear Information System (INIS)

    We report our investigation on the surface properties of sinusoidal roughness standards made from pure electroformed nickel. Two specimens having a sinusoidal profile with nominal Raof 0.36 μm and a peak spacing of 25 μm are chosen for this investigation. One specimen is further treated with a hard protective coating of nickel-boron. The surface topography, friction, hardness and Young's modulus of the specimens were measured by a novel instrument, the multi-function Tribological Probe Microscope (TPM). The results show that hardness of these two specimens is 14.1 GPa for uncoated specimen and 25.7 GPa for the coated one, while the Young's modulus is 188 GPa and 225 GPa, respectively. The ramping force was set to 3mN for both the specimens and the effect of the tip penetration was investigated by comparing the topography measurements before and after hardness mapping. It has been found out that there is no significant change in the averaged profiles over the scanned area, which indicates the topography distortion seen in the multi-function mapping, is recoverable. Cross correlation between topography and its corresponding hardness/Young's modulus has been carried out and the result will be discussed in the paper

  7. Constraining the surface properties of effective Skyrme interactions

    CERN Document Server

    Jodon, R; Bennaceur, K; Meyer, J

    2016-01-01

    The purpose of this study is threefold: first, to identify a scheme for the determination of the surface energy coefficient a_surf that offers the best compromise between robustness, precision, and numerical efficiency; second, to analyze the correlation between values for a_surf and the characteristic energies of the fission barrier of Pu240; and third, to lay out a procedure how the deformation properties of the Skyrme energy density functional (EDF) can be constrained during the parameter fit. There are several frequently used possibilities to define and calculate the surface energy coefficient a_surf of effective interactions. The most direct access is provided by the model system of semi-infinite nuclear matter, but a_surf can also be extracted from the systematics of binding energies of finite nuclei. Calculations can be carried out either self-consistently (HF), which incorporates quantal shell effects, or in one of the semi-classical Extended Thomas-Fermi (ETF) or Modified Thomas-Fermi (MTF) approxima...

  8. Behavior of plasma facing surfaces in the large helical device

    International Nuclear Information System (INIS)

    Material probes have been installed at the inner walls along the poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was thoroughly cleaned by helium glow discharge conditioning. For the 3rd and 4th campaigns, graphite tiles were installed over the entire divertor strike region, and then the wall condition was significantly changed compared to the case of a stainless steel wall. Graphite erosion took place during the main discharges and the eroded carbon was deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, the amount of retained discharge gases such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristic of the LHD wall is a large retention of helium gas since the wall temperature is limited to below 368 K. In order to reduce the recycling of discharge gas, wall heating before the experimental campaign and surface heating between the main discharge shots are planned. (author)

  9. Behavior of plasma facing surface in the large helical device

    International Nuclear Information System (INIS)

    Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned. (author)

  10. Behavior of plasma facing surface in the large helical device

    Energy Technology Data Exchange (ETDEWEB)

    Hino, T.; Nobuta, Y. [Hokkaido Univ., Dept. of Nuclear Engineering, Sapporo, Hokkaido (Japan); Sagara, A. [National Inst. for Fusion Science, Toki, Gifu (Japan)] [and others

    2002-11-01

    Material probes have been installed at the inner walls along poloidal direction in LHD from the first experimental campaign. After each campaign, the impurity deposition and the gas retention have been examined to clarify the plasma surface interaction and the degree of wall cleaning. In the 2nd campaign, the entire wall was considerably cleaned by helium glow discharge conditionings. For the 3rd and 4th campaigns, graphite tiles were installed at entire divertor strike region, and then the wall condition significantly changed compared to the case of stainless steel wall. The erosion of graphite took place during the main discharges and the eroded carbon deposited on the entire wall. In particular, the deposition thickness was large at the wall far from the plasma. Since the entire wall was well carbonized, amount of retained discharge gas such as H and He became large. In particular, the helium retention was large at the position close to the anodes used for helium glow discharge cleanings. One characteristics of the LHD wall is a large retention of helium gas since the wall temperature is limited below 368 K. In order to reduce the recycling of discharge gas, the wall heating before the experimental campaign and the surface heating between the main discharge shots are planned. (author)

  11. Cell adhesion behavior on the silicone rubber surface modified by using ion beam irradiation

    International Nuclear Information System (INIS)

    In this study we studied cell adhesion and proliferation on the surface of a silicone rubber modified by ion beam irradiation. The surface property of the irradiated silicone rubber was characterized by water contact angle and FT-IR analyses. It was observed that human (HEK293) fibroblast cells exhibit strong adhesion to the irradiated silicone surface. This enhanced adhesion of mammalian cells can be attributed to the increase in the hydrophilicity of the silicone surface by ion beam irradiation

  12. Phase behavior, structure, and properties of colloidal microsphere-nanoparticle mixtures

    Science.gov (United States)

    Tohver, Valeria

    2001-10-01

    We have studied the phase behavior, structure and properties of binary mixtures of negligibly charged colloidal microspheres and highly repulsive nanoparticles. The interactions between such species were investigated via scanning angle reflectometry, zeta potential measurements, and sedimentation studies. At pH zeta potential of 65 mV and the colloidal microspheres are negligibly charged with a measured zeta potential of roughly 1 mV. Under these conditions, scanning angle reflectometry measurements indicated no nanoparticle adsorption occurs on model silica surfaces (i.e., oxidized silicon wafers). However, zeta potential measurements carried out on dilute microsphere suspensions revealed that these microspheres exhibited an effective charge buildup as a function of nanoparticle volume fraction at pH = 1.5. This behavior which we refer to as nanoparticle haloing can stem solely from their repulsive interactions in solution and has a profound effect on the phase behavior, structure and properties of these binary mixtures. The phase behavior, structure, and properties of binary mixtures of negligibly charged colloidal microspheres were studied for two size ratios of 95 and 197 at pH = 1.5. In the absence of nanoparticle additions, the system spontaneously assembled into a colloidal gel whose strength increased with microsphere volume fraction. Between a lower and upper critical nanoparticle volume fraction, such binary mixtures formed a stable fluid phase due to nanoparticle haloing. In this concentration regime, colloidal microsphere crystals could be assembled under gravity-driven sedimentation. Confocal microscopy revealed that such crystals exhibited a center-to-center microsphere separation distance of 2 amusphere, where amusphere is the microsphere radius. Above the upper critical nanoparticle volume fraction, depletion flocculation induced by the presence of highly charged nanoparticles in solution led to the reformation of a colloidal gel phase. The

  13. Enzyme behavior at surfaces. Site-specific variants of subtilisin BPN' with enhanced surface stability.

    Science.gov (United States)

    Brode, P F; Erwin, C R; Rauch, D S; Lucas, D S; Rubingh, D N

    1994-09-23

    Enzyme adsorption and inactivation at the solid/liquid interface for subtilisin BPN' show a strong dependence on the nature of the solid surface. Adsorption of BPN' at the solid/liquid interface is considerably greater for a hydrophobic surface than for a hydrophilic one. Likewise, the rate of inactivation of the wild-type BPN' is over five times greater when equilibrated with a hydrophobic surface than with a hydrophilic surface. The rate data from these enzyme inactivation experiments performed at 50 degrees C are best fit by a second-order kinetic equation, suggesting a bimolecular pathway to inactivation. The role of increased surface adsorption on this bimolecular inactivation is discussed in terms of two different mechanisms. Several site-specific variants of subtilisin BPN' have been made in an attempt to alter the surface-inactivation of the wild-type enzyme. The extent of adsorption on the model surfaces is significantly lowered by certain lysine to phenylalanine changes in BPN'. Consequently, the surface autolytic stability shows a 4-fold improvement. The change in surface autolytic stability is achieved even though the basic kinetic parameters (kcat and KM) of the variant enzymes are not significantly different on a soluble substrate. The results provide insights into the use of mutagenesis to probe the mechanism of protein interactions with surfaces. PMID:8089121

  14. Experimental and numerical studies on free surface behavior of windowless target

    International Nuclear Information System (INIS)

    The formation and control method of coolant free surface is one of the key technology for the design of windowless target in Accelerator Driven System (ADS). In recent study, experimental and CFD investigations on free surface behavior are performed in a scaled windowless target model by using water as test fluid. The method of laser light sheet is applied for visualization of the flow field. Experiments are carried out at various Reynolds numbers. The structure and features of the flow vortex are investigated. In addition, CFD simulation is performed by using both Fluent and OpenFOAM platform. The effect of different turbulence models, such as k-ω model, Reynolds stress model and LES model, on the velocity profile and free surface behavior are tested. The numerical results of LES model agree qualitatively well with the experimental data related to both flow field and free surface behavior. (authors)

  15. Investigation of Surface Properties for Gallium- and Nitrogen-polar Gallium Nitride using Scanning Probe Microscopy Techniques

    Science.gov (United States)

    Ferguson, Josephus Daniel, III

    Because the surface plays an important role in the electrical and optical properties of GaN devices, an improved understanding of surface effects should help optimize device performance. In this work, atomic force microscopy (AFM) and related techniques have been used to characterize three unique sets of n-type GaN samples. The sample sets comprised freestanding bulk GaN with Ga-polar and N-polar surfaces, epitaxial GaN films with laterally patterned Ga- and N-polar regions on a common surface, and truncated, hexagonal GaN microstructures containing Ga-polar mesas and semipolar facets. Morphology studies revealed that bulk Ga-polar surfaces treated with a chemical-mechanical polish (CMP) were the flattest of the entire set, with rms values of only 0.4 nm. Conducting AFM (CAFM) indicated unexpected insulating behavior for N-polar GaN bulk samples, but showed expected forward and reverse-bias conduction for periodically patterned GaN samples. Using scanning Kelvin probe microscopy, these same patterned samples demonstrated surface potential differences between the two polarities of up to 0.5 eV, where N-polar showed the expected higher surface potential. An HCl cleaning procedure used to remove the surface oxide decreased this difference between the two regions by 0.2 eV. It is possible to locally inject surface charge and measure the resulting change in surface potential using CAFM in conjunction with SKPM. After injecting electrons using a 10 V applied voltage between sample and tip, the patterned polarity samples reveal that the N-polar regions become significantly more negatively charged as compared to Ga-polar regions, with up to a 2 eV difference between charged and uncharged N-polar regions. This result suggests that the N-polar regions have a thicker surface oxide that effectively stores charge. Removal of this oxide layer using HCl results in significantly decreased surface charging behavior. A phenomenological model was then developed to fit the discharging

  16. Study of surface tension and surface properties of binary systems of DMSO with long chain alcohols at various temperatures

    International Nuclear Information System (INIS)

    Highlights: • Surface tension of binary mixtures of alcohol/DMSO determined. • Surface mole fraction and surface thermodynamic parameters were calculated. • The surface tension data of binary mixtures were correlated with FLW, LWW and MS models. -- Abstract: Surface tensions of binary mixtures of DMSO (dimethyl sulphoxide) with a series of long chain aliphatic alcohols (1-propanol, 1-butanol, and 1-hexanol) were measured as a function of composition using the ring detachment method in the temperature range between (288.15 and 328.15) K. The surface tension results are used to describe quantitatively the nature, properties, and compositions of surface layers in binary liquid mixtures. The temperature influence on the behaviour of surface tensions and surface properties of binary mixtures has often been used to obtain information about solute structural effects on DMSO. The surface tension of the above mentioned binary systems were correlated with empirical and thermodynamic based models. The average relative error obtained from the comparison of experimental and calculated surface tension values for 15 binary systems with three models is less than 1%. In addition to finding more information about the surface structure of binary mixtures, surface mole fraction was calculated using an extended Langmuir model (EL). The temperature dependence of σ at fixed composition of solutions was used to estimate surface enthalpy, Hs, and surface entropy, Ss. The results provide information on the molecular interactions between the unlike molecules that exist at the surface and the bulk

  17. Superhydrophobic and adhesive properties of surfaces: testing the quality by an elaborated scanning electron microscopy method.

    Science.gov (United States)

    Ensikat, Hans J; Mayser, Matthias; Barthlott, Wilhelm

    2012-10-01

    In contrast to advancements in the fabrication of new superhydrophobic materials, the characterization of their water repellency and quality is often coarse and unsatisfactory. In view of the problems and inaccuracies, particularly in the measurement of very high contact angles, we developed alternative methods for the characterization of superhydrophobic surfaces. It was found that adhering water remnants after immersion are a useful criterion in determining the repellency quality. In this study, we introduce microscopy methods to detect traces of water-resembling test liquids on superhydrophobic surfaces by scanning electron microscopy (SEM) or fluorescence light microscopy (FLM). Diverse plant surfaces and some artificial superhydrophobic samples were examined. Instead of pure water, we used aqueous solutions containing a detectable stain and glycerol in order to prevent immediate evaporation of the microdroplets. For the SEM examinations, aqueous solutions of lead acetate were used, which could be detected in a frozen state at -90 °C with high sensitivity using a backscattered electron detector. For fluorescence microscopy, aqueous solutions of auramine were used. On different species of superhydrophobic plants, varying patterns of remaining microdroplets were found on their leaves. On some species, drop remnants occurred only on surface defects such as damaged epicuticular waxes. On others, microdroplets regularly decorated the locations of increased adhesion, particularly on hierarchically structured surfaces. Furthermore, it is demonstrated that the method is suitable for testing the limits of repellency under harsh conditions, such as drop impact or long-enduring contact. The supplementation of the visualization method by the measurement of the pull-off force between a water drop and the sample allowed us to determine the adhesive properties of superhydrophobic surfaces quantitatively. The results were in good agreement with former studies of the water

  18. Effect of surface property on electrochemical kinetics in high temperature water

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.J.; Andresen, P.L. [GE Corporate Research and Development, Schenectady, NY (United States)

    2002-07-01

    The effect of various surface properties on the polarization behavior of hydrogen (H{sub 2}) oxidation, oxygen (O{sub 2}) reduction, and electrochemical corrosion potential (ECP) on 304 stainless steel (SS) in high temperature, high purity water was studied. It is evident that the presence of noble metals on the oxide surface dramatically improves the hydrogen oxidation kinetics and thus enhances the catalytic recombination efficiency of H{sub 2} to O{sub 2} to form H{sub 2}O. The enhancement in the catalytic nature on 304 SS surface doped with noble metals results in a thermodynamically lowest electrochemical corrosion potential (ECP) value (<-500 mV vs. standard hydrogen electrode, SHE) when a stoichiometric or higher amount of hydrogen is present in the water. It is also observed that the insulated protective coating (IPC) layer created with a powder of yttria-stabilized zirconia (YSZ) by the thermal spray restricted the oxidant transport rate to the metal surface, and the ECP remained at <-500 mV{sub she} in 288 C water without addition of hydrogen (H{sub 2}). (authors)

  19. Initial oxidation behaviors of nitride surfaces of uranium by XPS analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kezhao, E-mail: liukz@hotmail.com [Department of Materials Science and Engineering, Zhejiang University, No. 38 Zheda Road, Hangzhou 310027 (China); Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Luo, Lizu; Luo, Lili [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China); Long, Zhong [China Academy of Engineering Physics, P.O. Box 919-71, Mianyang 621907 (China); Hong, Zhanglian, E-mail: hong_zhanglian@zju.edu.cn [Department of Materials Science and Engineering, Zhejiang University, No. 38 Zheda Road, Hangzhou 310027 (China); Yang, Hui [Department of Materials Science and Engineering, Zhejiang University, No. 38 Zheda Road, Hangzhou 310027 (China); Wu, Sheng [Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, Mianyang 621907 (China)

    2013-09-01

    The nitride surfaces of uranium were prepared by the surface glow plasma nitriding (SGPN) and plasma immersion ion implantation (PIII) methods. The initial oxidation behaviors of modified surfaces were studied by X-ray photoelectron spectroscopy (XPS). The SGPN on the uranium surface led to a single layer of uranium sesquinitride (U{sub 2}N{sub 3}), while the PIII on the surface resulted in a compound layer composed of U{sub 2}N{sub 3} and uranium dioxide (UO{sub 2}). The oxygen covered on these modified layers led to the formation of UO{sub 2} from U{sub 2}N{sub 3} and U{sub 2}N{sub 3} from UN. The oxidized nitrogen species were also observed on the two types of nitriding layers, with the discussion of the N–O coaction behaviors.

  20. Non-universal behavior of leaky surface waves in a one dimensional asymmetric plasmonic grating

    Science.gov (United States)

    Vempati, Sesha; Iqbal, Tahir; Afsheen, Sumera

    2015-07-01

    We report on a non-universal behavior of leaky surface plasmon waves on asymmetric (Si/Au/analyte of different height) 1D grating through numerical modelling. The occurrence of the leaky surface wave was maximized (suppressing the Fabry-Perot cavity mode), which can be identified in a reflection spectrum through characteristic minimum. Beyond a specific analyte height (h), new sets of surface waves emerge, each bearing a unique reflection minimum. Furthermore, all of these minima depicted a red-shift before saturating at higher h values. This saturation is found to be non-universal despite the close association with their origin (being leaky surface waves). This behavior is attributed to the fundamental nature and the origin of the each set. Additionally, all of the surface wave modes co-exit at relatively higher h values.

  1. Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel

    International Nuclear Information System (INIS)

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polymer was dispersed in polyvinylacetate and coated on carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating on carbon steel in 3% NaCl were investigated using open-circuit potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating a certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel throughout the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel

  2. Reinforcements affect mechanical properties and wear behaviors of WC clad layer by gas tungsten arc welding

    International Nuclear Information System (INIS)

    Highlights: ► WC particles react completely with the steel matrix during the GTAW process. ► The same specimen has different morphologies under the SEM and OM. ► The evolution of this microstructure is proposed. ► Fe3W3C and M7C3 phases clearly affected the hardness and wear performance. -- Abstract: This work deals with the surface analysis, mechanical properties and wear performances of the clad layer, which is made from tungsten carbide (WC) powders on SKD61 die steel by the gas tungsten arc welding method. According to the experimental results, due to the high hardness and elastic modulus reinforcements (Fe3W3C and M7C3) existing in the WC clad layer, the WC clad specimen has excellent wear performance at different sliding speeds. According to the wear analysis, wear behaviors of the WC clad layer are two-body abrasion and oxidation wear. In addition, oxidation wear dominates the wear behaviors of the SKD61 die steel specimen at different sliding speeds.

  3. Behavioral Properties of Correlated Equilibrium; Social Group Structures with Conformity and Stereotyping

    OpenAIRE

    Edward Cartwright; Myrna Wooders

    2008-01-01

    We explore the potential for correlated equilibrium to capture conformity to norms and the coordination of behavior within social groups. Given a partition of players into social groups we propose properties that one may expect of a correlated equilibrium: within-group anonymity, group independence, predictable group behavior and stereotyped beliefs. We then demonstrate that (a) a correlated equilibrium satisfying these properties exists in games with many players (b) a player who stereotypes...

  4. Comparison of waxy and normal potato starch remaining granules after chemical surface gelatinization: Pasting behavior and surface morphology

    NARCIS (Netherlands)

    Huang, J.; Chen Zenghong,; Xu, Yalun; Li, Hongliang; Liu, Shuxing; Yang, Daqing; Schols, H.A.

    2014-01-01

    o understand the contribution of granule inner portion to the pasting property of starch, waxy potato starch and two normal potato starches and their acetylated starch samples were subjected to chemical surface gelatinization by 3.8 mol/L CaCl2 to obtain remaining granules. Native and acetylated, or

  5. Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots.

    Directory of Open Access Journals (Sweden)

    Miguel Duarte

    Full Text Available Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers.

  6. Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface Robots.

    Science.gov (United States)

    Duarte, Miguel; Costa, Vasco; Gomes, Jorge; Rodrigues, Tiago; Silva, Fernando; Oliveira, Sancho Moura; Christensen, Anders Lyhne

    2016-01-01

    Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most studies have been conducted in simulation, and the few that have been conducted on real robots have been confined to laboratory environments. In this paper, we demonstrate for the first time a swarm robotics system with evolved control successfully operating in a real and uncontrolled environment. We evolve neural network-based controllers in simulation for canonical swarm robotics tasks, namely homing, dispersion, clustering, and monitoring. We then assess the performance of the controllers on a real swarm of up to ten aquatic surface robots. Our results show that the evolved controllers transfer successfully to real robots and achieve a performance similar to the performance obtained in simulation. We validate that the evolved controllers display key properties of swarm intelligence-based control, namely scalability, flexibility, and robustness on the real swarm. We conclude with a proof-of-concept experiment in which the swarm performs a complete environmental monitoring task by combining multiple evolved controllers. PMID:26999614

  7. The effect of surfaces type on vibration behavior of piezoelectric micro-cantilever close to sample surface in a humid environment based on MCS theory

    Science.gov (United States)

    Korayem, M. H.; Korayem, A. H.

    2016-08-01

    Atomic force microscopy (AFM) has been known as an innovative tool in the fields of surface topography, determination of different mechanical properties and manipulation of particles at the micro- and nanoscales. This paper has been concerned with advanced modeling and dynamic simulation of AFM micro-cantilever (MC) in the amplitude mode in the air environment. To increase the accuracy of the governing equations, modified couple stress theory appropriate in micro- and nanoscales has been utilized based on Timoshenko beam theory in the air environment near the sample surface. Also, to discretize the equations, differential quadrature method has been recommended. In modeling, geometric discontinuities due to the presence of a piezoelectric layer enclosed between two electrode layers and the change in MC cross section when connected to the MC have been considered. In addition to the effect of MC modeling on the accuracy of modeling and vibration amplitude during surface topography, understanding and modeling the environmental forces in the air environment, including van der Waals, capillary and contact forces, are important. This paper has been provided more accurate environmental forces modeling and has been investigated the vibration behavior of piezoelectric MC in the humid environment. Moreover, this paper has been examined the maximum and minimum MC amplitude in the air environment close to the surface with different kinds of topography. The results illustrate that kind of surfaces has effect on the maximum and minimum amplitude due to the decrease or increase in equilibrium MC distance.

  8. Impact of surface porosity and topography on the mechanical behavior of high strength biomedical polymers.

    Science.gov (United States)

    Evans, Nathan T; Irvin, Cameron W; Safranski, David L; Gall, Ken

    2016-06-01

    The ability to control the surface topography of orthopedic implant materials is desired to improve osseointegration but is often at the expense of mechanical performance in load bearing environments. Here we investigate the effects of surface modifications, roughness and porosity, on the mechanical properties of a set of polymers with diverse chemistry and structure. Both roughness and surface porosity resulted in samples with lower strength, failure strain and fatigue life due to stress concentrations at the surface; however, the decrease in ductility and fatigue strength were greater than the decrease in monotonic strength. The fatigue properties of the injection molded polymers did not correlate with yield strength as would be traditionally observed in metals. Rather, the fatigue properties and the capacity to maintain properties with the introduction of surface porosity correlated with the fracture toughness of the polymers. Polymer structure impacted the materials relative capacity to maintain monotonic and cyclic properties in the face of surface texture and porosity. Generally, amorphous polymers with large ratios of upper to lower yield points demonstrated a more significant drop in ductility and fatigue strength with the introduction of porosity compared to crystalline polymers with smaller ratios in their upper to lower yield strength. The latter materials have more effective dissipation mechanisms to minimize the impact of surface porosity on both monotonic and cyclic damage. PMID:26986085

  9. Electrostatic Properties of N-Acetyl-Cysteine-Coated Gold Surfaces Interacting with ZrO{sub 2} Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jinwon [Seoul National Univ. of Science and Technology, Seoul (Korea, Republic of)

    2012-09-15

    The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the ZrO{sub 2} surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the ZrO{sub 2} surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.

  10. Electrostatic Properties of N-Acetyl-Cysteine-Coated Gold Surfaces Interacting with ZrO2 Surfaces

    International Nuclear Information System (INIS)

    The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the ZrO2 surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the ZrO2 surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface

  11. Distance Measurements and Stellar Population Properties via Surface Brightness Fluctuations

    CERN Document Server

    Fritz, Alexander

    2012-01-01

    Surface Brightness Fluctuations (SBFs) are one of the most powerful techniques to measure the distance and to constrain the unresolved stellar content of extragalactic systems. For a given bandpass, the absolute SBF magnitude \\bar{M} depends on the properties of the underlying stellar population. Multi-band SBFs allow scientists to probe different stages of the stellar evolution: UV and blue wavelength band SBFs are sensitive to the evolution of stars within the hot Horizontal Branch (HB) and post-Asymptotic Giant Branch (post-AGB) phase, whereas optical SBF magnitudes explore the stars within the Red Giant Branch (RGB) and HB regime. Near- and Far-infrared SBF luminosities probe the important stellar evolution stage within the AGB and Thermally-Pulsating Asymptotic Giant Branch (TP-AGB) phase. Since the first successful application by Tonry and Schneider, a multiplicity of works have used this method to expand the distance scale up to 150 Mpc and beyond. This article gives a historical background of distance...

  12. Standard Fire Behavior Fuel Models : A Comprehensive Set for Use with Rothermel's Surface Fire Spread Model

    OpenAIRE

    Scott, Joe H; Burgan, Robert E

    2005-01-01

    This report describes a new set of standard fire behavior fuel models for use with Rothermel’s surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

  13. Fire Behavior Modeling - Experiment on Surface Fire Transition to the Elevated Live Fuel

    OpenAIRE

    Omodan, Sunday

    2015-01-01

    ABSTRCT OF THE THESISFire Behavior Modeling - Experiment on Surface Fire Transition to the Elevated Live Fuelby Sunday OmodanMaster of Science, Graduate Program in Mechanical EngineeringUniversity of California, Riverside, June 2015Dr. Marko Princevac, ChairpersonRecent increase in the number of wildfires globally over the last decade has made fire behavior modelling a major subject of scientific concern. Although, there have been wildfire studies since the beginning of 19th century, and thi...

  14. Tailoring Novel PTFE Surface Properties: Promoting Cell Adhesion and Antifouling Properties via a Wet Chemical Approach.

    Science.gov (United States)

    Gabriel, Matthias; Niederer, Kerstin; Becker, Marc; Raynaud, Christophe Michel; Vahl, Christian-Friedrich; Frey, Holger

    2016-05-18

    Many biomaterials used for tissue engineering applications lack cell-adhesiveness and, in addition, are prone to nonspecific adsorption of proteins. This is especially important for blood-contacting devices such as vascular grafts and valves where appropriate surface properties should inhibit the initial attachment of platelets and promote endothelial cell colonization. As a consequence, the long-term outcome of the implants would be improved and the need for anticoagulation therapy could be reduced or even abolished. Polytetrafluoroethylene (PTFE), a frequently used polymer for various medical applications, was wet-chemically activated and subsequently modified by grafting the endothelial cell (EC) specific peptide arginine-glutamic acid-aspartic acid-valine (REDV) using a bifunctional polyethylene glycol (PEG)-spacer (known to reduce platelet and nonspecific protein adhesion). Modified and control surfaces were both evaluated in terms of EC adhesion, colonization, and the attachment of platelets. In addition, samples underwent bacterial challenges. The results strongly suggested that PEG-mediated peptide immobilization renders PTFE an excellent substrate for cellular growth while simultaneously endowing the material with antifouling properties. PMID:27041509

  15. A study on the dynamic behaviors of water droplets impacting nanostructured surfaces

    Directory of Open Access Journals (Sweden)

    Geunjae Kwak

    2011-12-01

    Full Text Available We have investigated the influence of impact velocity and intrinsic surface wettability of nanostructures on the impact dynamic behaviors of water droplets on nanostructure surfaces. Nanowires array surfaces with tunable wettabilities ranging from superhydrophilic to superhydrophobic were fabricated by the deposition of surface modifiers differing in alkyl chain length. The transition criteria of rebound/wetting state and rebound/splashing state based on the relationship between the Webber (We number and the surface free energy were determined. We have confirmed that the critical We number that determines the transition of the rebound/wetting increased as surface energy decreased. Additionally, the We number at which fragmentation occurred on our superhydrophobic surface was relatively low compared to previously reported values.

  16. Surface Damage Behavior of Galvanized Steel Sheets in Forming Process Under Tension-Bending

    Science.gov (United States)

    Yu, Z. Q.; Hou, Y. K.; Li, S. H.; Lin, Z. Q.; Zhang, W. G.

    The surface damage behaviors of different galvanized steel sheets were investigated under the condition of tension-bending. The U-channel forming tests were performed for HDGI (hot-dip galvanized) and HDGA (hot-dip galvannealed) steels. Experimental results indicate that HDGI steel shows better damage resistance than HDGA steel in sheet metal forming. Scratching is the main surface damage in the forming of HDGI steel while exfoliating and scratching of coating are two types of surface damage for HDGA steel. And tool hardness and surface topography have crucial effects on part surface damage in the forming of the two kinds of galvanized steels. Different surface treatments should be applied to the forming tools in the forming of HDGI and HDGA steels for better surface qualities of products.

  17. Effects of heating rate on slow pyrolysis behavior, kinetic parameters and products properties of moso bamboo.

    Science.gov (United States)

    Chen, Dengyu; Zhou, Jianbin; Zhang, Qisheng

    2014-10-01

    Effects of heating rate on slow pyrolysis behaviors, kinetic parameters, and products properties of moso bamboo were investigated in this study. Pyrolysis experiments were performed up to 700 °C at heating rates of 5, 10, 20, and 30 °C/min using thermogravimetric analysis (TGA) and a lab-scale fixed bed pyrolysis reactor. The results show that the onset and offset temperatures of the main devolatilization stage of thermogravimetry/derivative thermogravimetry (TG/DTG) curves obviously shift toward the high-temperature range, and the activation energy values increase with increasing heating rate. The heating rate has different effects on the pyrolysis products properties, including biochar (element content, proximate analysis, specific surface area, heating value), bio-oil (water content, chemical composition), and non-condensable gas. The solid yields from the fixed bed pyrolysis reactor are noticeably different from those of TGA mainly because the thermal hysteresis of the sample in the fixed bed pyrolysis reactor is more thorough. PMID:25063973

  18. Effect of gamma irradiation on the behavioral properties of crotoxin

    Directory of Open Access Journals (Sweden)

    E.G. Moreira

    1997-02-01

    Full Text Available Crotoxin has been detoxified with gamma radiation in order to improve crotalic antiserum production. Nevertheless, present knowledge of the biological characteristics of irradiated crotoxin is insufficient to propose it as an immunizing agent. Crotoxin is known to increase the emotional state of rats and to decrease their exploratory behavior (Moreira EG, Nascimento N, Rosa GJM, Rogero JR and Vassilieff VS (1996 Brazilian Journal of Medical and Biological Research, 29: 629-632. Therefore, we decided 1 to evaluate the effects of crotoxin in the social interaction test, which has been widely used for the evaluation of anxiogenic drugs, and 2 to determine if irradiated crotoxin induces behavioral alterations similar to those of crotoxin in the social interaction, open-field and hole-board tests. Male Wistar rats (180-220 g were used. Crotoxin (100, 250, and 500 µg/kg was injected intraperitoneally 2 h before the social interaction test. Similarly, irradiated crotoxin (2000 Gy gamma radiation from a 60Co source was administered at the doses of 100, 250, and 500 µg/kg for the hole-board test, and at the doses of 1000 and 2500 µg/kg for the open-field and social interaction tests. ANOVA complemented with the Dunnett test was used for statistical analysis (P<0.05. Crotoxin decreased the social interaction time (s at the doses of 100, 250 and 500 µg/kg (means ± SEM from 51.6 ± 4.4 to 32.6 ± 3.7, 28.0 ± 3.6 and 31.6 ± 4.4, respectively. Irradiated crotoxin did not induce behavioral alterations. These results indicate that 1 crotoxin may be an anxiogenic compound, and 2 in contrast to crotoxin, irradiated crotoxin was unable to induce behavioral alterations, which makes it a promising compound for the production of crotalic antiserum

  19. Influence of Temperature on the Frictional Properties of Water-Lubricated Surfaces

    Directory of Open Access Journals (Sweden)

    Troels Røn

    2014-10-01

    Full Text Available The influence of temperature on the lubricating properties of neat water for tribopairs with varying bulk elasticity moduli and surface hydrophilicity, namely hard-hydrophobic interface (h-HB, hard-hydrophilic interface (h-HL, soft-hydrophobic interface (s-HB, and soft-hydrophilic interface (s-HL, has been investigated. With increasing temperature, the coefficients of friction generally increased due to the decreasing viscosity of water. This change was more clearly manifested from soft interfaces for more feasible formation of lubricating films. Nevertheless, dominant lubrication mechanism appears to be boundary and mixed lubrication even for soft interfaces at all speeds (up to 1200 mm/s and temperatures (1 to 90 °C investigated. The results from this study are expected to provide a reference to explore the temperature-dependent tribological behavior of more complex aqueous lubricants, e.g., those involving various additives, for a variety of tribosystems.

  20. Surface chemical and morphological properties of mechanical pulps, fibers and fines

    OpenAIRE

    Kangas, Heli

    2007-01-01

    The aim of this work was to study the surface chemical and morphological properties of different mechanical pulps with special focus on the effects of refining, bleaching and enzymatic modification on the surface properties of the isolated pulp fractions, namely fibers, fibrillar fines and flake-like fines. Special emphasis was placed on evaluating the suitability of time-of-flight secondary ion mass spectroscopy (ToF-SIMS) for studying the surface chemical properties of pulps and pulp fracti...

  1. Characterization and mapping of surface physical properties of Mars from CRISM multi-angular data: application to Gusev Crater and Meridiani Planum

    CERN Document Server

    Fernando, J; Pilorget, C; Pinet, P; Ceamanos, X; Douté, S; Daydou, Y; Costard, F

    2014-01-01

    The analysis of the surface texture from the particle (grain size, shape and internal structure) to its organization (surface roughness) provides information on the geological processes. CRISM multi-angular observations (varied emission angles) allow to characterize the surface scattering behavior which depends on the composition but also the material physical properties (e.g., grain size, shape, internal structure, the surface roughness). After an atmospheric correction by the Multi-angle Approach for Retrieval of the Surface Reflectance from CRISM Observations, the surface reflectances at different geometries are analyzed by inverting the Hapke photometric model depending on the single scattering albedo, the 2-term phase function, the macroscopic roughness and the 2-term opposition effects. Surface photometric maps are created to observe the spatial variations of surface scattering properties as a function of geological units at the CRISM spatial resolution (200m/pixel). An application at the Mars Explorati...

  2. Reflection properties of road surfaces. Contribution to OECD Scientific Expert Group AC4 on Road Surface Characteristics.

    OpenAIRE

    Schreuder, D.A.

    1983-01-01

    Photometric characteristics of road surfaces are dealt with. Representation of reflection properties in public lighting; quality criteria of road lighting installations; classification of road surfaces; the relation between reflection characteristics and other properties of road pavements in public lighting; lighting with vehicle lights, daylight conditions; lighting with vehicle lights; daylight; and road markings are described in part I. Part II presents the measurement of reflection proper...

  3. Behavior of rod-like polyelectrolytes near an oppositely charged surface

    OpenAIRE

    Messina, Rene

    2005-01-01

    The behavior of highly charged short rod-like polyelectrolytes near oppositely charged planar surfaces is investigated by means of Monte Carlo simulations. A detailed microstructural study, including monomer and fluid charge distribution, and chain orientation, is provided. The influence of chain length, substrate's surface-charge-density and image forces is considered. Due to the lower chain-entropy (compared to flexible chains), our simulation data show that rod-like polyelectrolytes can, i...

  4. Influence of surface silica impurities on the sintering behavior of alumina powders

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J.S.; Pask, J.A.

    1980-02-01

    The filtering, pressing and sintering behavior of an alumina powder with and without silica impurity on surface has been studied. When silica is removed from surface by HF-treatment and compactibility is considerably enhanced due to the different acidity/basicity nature of the OH of the hydroxyl layers. The silica impurity decreases the activation energy of the initial stage of sintering and grain boundary energy, improves the densification process and exerts a moderate inhibitor effect on the grain growth.

  5. A means to an interface: investigating monoethanolamine behavior at an aqueous surface.

    Science.gov (United States)

    McWilliams, Laura E; Valley, Nicholas A; Wren, Sumi N; Richmond, Geraldine L

    2015-09-01

    The use of amine scrubbers to trap carbon dioxide from flue gas streams is one of the most promising avenues for atmospheric carbon dioxide reduction. However, modifications are necessary to efficiently scale these scrubbers for use in fossil fuel plants. Current advances in tailoring amines for CO2 capture involve improvements of bulk kinetic and thermodynamic parameters, with little consideration to surface chemistry and behavior. Aqueous alkanolamine solutions, such as monoethanolamine (MEA), are currently highly favored sorbents in CO2 post-combustion capture. Although numerous studies have explored MEA-CO2 chemistry at the macroscopic scale, few have investigated the role of the interface in the gas adsorption process. Additionally, as these amines become more industrially ubiquitous, their presence on and the need to understand their behavior at atmospheric and environmental surfaces will increase. This study investigates the surface behavior of monoethanolamine at the vapor/water interface, with particular focus on MEA's surface orientation and footprint. Using vibrational sum frequency spectroscopy, surface tensiometry, and computational techniques, MEA is found to adopt a constrained gauche interfacial conformation with its methylene backbone oriented toward the vapor phase and its functional groups solvated in the bulk solution. Computational and experimental analysis agree well, giving a complete picture with vibrational mode assignments and surface orientation of MEA. These findings can assist in the tailoring of amine structures or to facilitate improvements in engineering design to exploit favorable surface chemistry, as well as to serve as a starting point toward understanding aqueous amine surface behavior relevant to environmental systems. PMID:26220791

  6. Novel procedure to enhance PLA surface properties by chitosan irreversible immobilization

    Science.gov (United States)

    Stoleru, Elena; Dumitriu, Raluca Petronela; Munteanu, Bogdanel Silvestru; Zaharescu, Traian; Tănase, Elisabeta Elena; Mitelut, Amalia; Ailiesei, Gabriela-Liliana; Vasile, Cornelia

    2016-03-01

    A novel two step procedure was applied for poly(lactic acid) (PLA) functionalization consisting in the exposure to cold radiofrequency plasma in nitrogen atmosphere or to gamma irradiation followed by "grafting to" of a chitosan layer using carbodiimide chemistry. The adhesion and stability of the deposited surface layer was assured by plasma/gamma irradiation treatment while the chitosan layer offers antifungal/antibacterial/antioxidant activities. Chitosan with different viscosities/deacetylation degree was deposited by electrospinning or immersion methods. Correlations between rheological behavior of chitosan solutions and chitosan layer deposition conditions are made. The PLA surface properties were investigated by water contact angle measurements, ATR-FTIR spectroscopy, AFM, chemiluminiscence, etc. It has been established that the surface roughness increases direct proportional with cold plasma duration and gamma irradiation dose and further increases by chitosan coating which at its turn depends on chitosan characteristics (viscosity and deacetylation degree) and method of deposition. Nano-fibers with relatively homogeneous and reproducible features are obtained by electrospinning of highly viscous chitosan while with the other two types of chitosan both microparticles and nano-fibers are formed. The chitosan coating obtained by immersion is more homogenous and compact and has a better antibacterial activity than the electrospun layer as fiber meshes.

  7. Impurities and Electronic Property Variations of Natural MoS 2 Crystal Surfaces

    KAUST Repository

    Addou, Rafik

    2015-09-22

    Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 < x < 2.05) at the surface. Thus, the variation in the conductivity, the work function, and stoichiometry across small areas of MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication. © 2015 American Chemical Society.

  8. Investigation of adsorption behavior of bisphenol A on well fabricated organic surfaces using surface plasmon resonance spectroscopy.

    Science.gov (United States)

    Moon, Jungwoo; Oh, Seogil; Kang, Taewook; Hong, Surin; Yi, Jongheop

    2006-11-01

    Molecular adsorption of bisphenol A (BPA) on three types of self-assembled monolayers with different functionalities, such as -CH3, -SH, and -COOH, was examined using surface plasmon resonance (SPR) spectroscopy. BPA molecules in an aqueous solution were easily adsorbed onto a hydrophobic surface compared to a hydrophilic surface. Sorption behavior of BPA into poly(2-methoxyethyl acrylate) (PMEA) layer, which is known as a biocompatible polymer, was also investigated. Sorption and desorption dynamics of BPA into PMEA were found to be very rapid and quite reversible. The swelling of PMEA by sorption of BPA results in the change in SPR angle and allows one to quantify the BPA concentration below 100 ppm. In addition, the transport mechanism of BPA within the membrane of organ can be inferred by the experimental results. PMID:17252807

  9. STUDIES ON THE MECHANICAL PROPERTIES AND CRYSTALLIZATION BEHAVIOR OF POLYETHYLENE COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    ZHU Jin; OU Yuchun; FENG Yupeng

    1995-01-01

    The effects of interfacial modifier on the mechanical, dynamic mechanical properties and crystallization behavior of the polyethylene composites were investigated in the present paper.It was found that the interfacial modifer significantly improved the mechanical properties,influenced the dynamic mechanical spectra and slightly changed the crystallization behavior.The results showed that the interfacial modifier changed the dispersion state of dispersed phase of the composites, resulting in different phase structure, which was the major reason leading to different mechanical and crystallization properties.

  10. Electrochemical behavior of Cu-Zn-Al shape memory alloy after surface modification by electroless plated Ni-P

    Institute of Scientific and Technical Information of China (English)

    LIANG Chenghao; CHEN Bangyi; CHEN Wan; WANG Hua

    2004-01-01

    The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with and without electroless plated Ni-P was investigated by electrochemical methods in artificial Tyrode's solution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode's solution. The anodic active current densities as well as electrochemical dissolution sensitivity of the electroless plated Ni-P Cu-Zn-Al SMA increased with NaCl concentration rising, pH of solution decreasing and environmental temperature uprising. X-ray diffraction analysis indicated that after surface modification by electroless plated Ni-P, an amorphous plated film formed on the surface of Cu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantly improve the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode's solution.

  11. The properties of a large sample of low surface brightness galaxies from SDSS

    CERN Document Server

    Liang, Y C; Chen, X Y; Gao, D; Hammer, F; Liu, F S; Hu, J Y; Deng, L C; Zhang, B

    2009-01-01

    A large sample of low surface brightness (LSB) disk galaxies is selected from SDSS with B-band central surface brightness mu_0(B) from 22 to 24.5 mag arcsec^(-2). Some of their properties are studied, such as magnitudes, surface brightness, scalelengths, colors, metallicities, stellar populations, stellar masses and multiwavelength SEDs from UV to IR etc. These properties of LSB galaxies have been compared with those of the galaxies with higher surface brightnesses. Then we check the variations of these properties following surface brightness.

  12. Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xujie [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng, Qingling, E-mail: biomater@mail.tsinghua.edu.cn [State key laboratory of new ceramics and fine processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Bachhuka, Akash [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); Vasilev, Krasimir [Mawson Institute, University of South Australia, Mawson Lakes 5095 (Australia); School of Advanced Manufacturing, University of South Australia, Mawson Lakes 5095 (Australia)

    2013-04-01

    This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (-NH{sub 2}), carboxyl (-COOH) and methyl (-CH{sub 3}), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (-COOH and -NH{sub 2}) can absorb more proteins than these modified with more hydrophobic functional group (-CH{sub 3}). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the -NH{sub 2} modified surfaces encourage osteogenic differentiation; the -COOH modified surfaces promote cell adhesion and spreading and the -CH{sub 3} modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

  13. Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

    Science.gov (United States)

    Liu, Xujie; Feng, Qingling; Bachhuka, Akash; Vasilev, Krasimir

    2013-04-01

    This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (sbnd NH2), carboxyl (sbnd COOH) and methyl (sbnd CH3), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (sbnd COOH and sbnd NH2) can absorb more proteins than these modified with more hydrophobic functional group (sbnd CH3). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the sbnd NH2 modified surfaces encourage osteogenic differentiation; the sbnd COOH modified surfaces promote cell adhesion and spreading and the sbnd CH3 modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

  14. Surface chemical functionalities affect the behavior of human adipose-derived stem cells in vitro

    International Nuclear Information System (INIS)

    This study examines the effect of surface chemical functionalities on the behavior of human adipose-derived stem cells (hASCs) in vitro. Plasma polymerized films rich in amine (-NH2), carboxyl (-COOH) and methyl (-CH3), were generated on hydroxyapatite (HAp) substrates. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy (XPS). The ability of different substrates to absorb proteins was evaluated. The results showed that substrates modified with hydrophilic functional group (-COOH and -NH2) can absorb more proteins than these modified with more hydrophobic functional group (-CH3). The behavior of human adipose-derived stem cells (hASCs) cultured on different substrates was investigated in vitro: cell counting kit-8 (CCK-8) analysis was used to characterize cell proliferation, scanning electronic microscopy (SEM) analysis was used to characterize cell morphology and alkaline phosphatase (ALP) activity analysis was used to account for differentiation. The results of this study demonstrated that the -NH2 modified surfaces encourage osteogenic differentiation; the -COOH modified surfaces promote cell adhesion and spreading and the -CH3 modified surfaces have the lowest ability to induce osteogenic differentiation. These findings confirmed that the surface chemical states of biomaterials can affect the behavior of hASCs in vitro.

  15. Role of surface stoichiometry on the interfacial electron behavior at Ni/TiO2(0 0 1) interfaces

    International Nuclear Information System (INIS)

    Highlights: ► Surface stoichiometry affects the interfacial charge re-distribution. ► Separation of electron–hole pairs depends on surface stoichiometry. ► Oxidization state of Ni depends on the initial conditions of the TiO2 surface. ► Insulator-to-metal transition affects the binding energies. - Abstract: The interfacial properties of Ni clusters grown on the stoichiometric and reduced rutile TiO2(0 0 1) surfaces were investigated by means of X-ray photoelectron spectroscopy (XPS). The binding energies (BE's) of elements from both overlayers and substrates were found to be affected by the formation of interfacial dipole. Regardless of the TiO2 surface stoichiometry, the Ni 2p3/2 BE's move monotonically toward lower value with the increase of Ni thickness due to the cluster size effect. However, the Ni 2p3/2 BE shift is much smaller on reduced TiO2(0 0 1) surfaces compared to that on the annealed stoichiometric surface. For stoichiometric and lightly reduced TiO2 surfaces, O 1s BE's exhibit an unexpected upward shift with increasing Ni thickness below 2 Å, and then downward shift to lower BE's when the Ni thickness increases further. This opposite tendency is attributed to the insulator-to-metal transition. On heavily reduced surface, only monotonically downward shift of the O 1s BE's was observed with the increase of Ni thickness. The different behaviors are well elucidated by collective contributions of interfacial charge transfer and image charge effect.

  16. Properties and thermal behavior of natural deep eutectic solvents

    OpenAIRE

    Craveiro, R.; Aroso, Ivo Manuel Ascensão; Flammia, V.; Carvalho, T.; Viciosa, M. T.; Dionísio, M.; Barreiros, S.; Reis, R. L.; Duarte, Ana Rita C.; Paiva, A.

    2016-01-01

    Natural deep eutectic solvents (NADES) have shown to be promising sustainable media for a wide range of applications. Nonetheless, very limited data is available on the properties of these solvents. A more comprehensive body of data on NADES is required for a deeper understanding of these solvents at molecular level, which will undoubtedly foster the development of new applications. NADES based on choline chloride, organic acids, amino acids and sugars were prepared, and their density, therma...

  17. Influence of protein bulk properties on membrane surface coverage during immobilization.

    Science.gov (United States)

    Militano, Francesca; Poerio, Teresa; Mazzei, Rosalinda; Piacentini, Emma; Gugliuzza, Annarosa; Giorno, Lidietta

    2016-07-01

    Biomolecules immobilization is a key factor for many biotechnological applications. For this purpose, the covalent immobilization of bovine serum albumin (BSA), lipase from Candida rugosa and protein G on differently functionalized regenerated cellulose membranes was investigated. Dynamic light scattering and electrophoresis measurements carried out on biomolecules in solution indicated the presence of monomers, dimers and trimers for both BSA and protein G, while large aggregates were observed for lipase. The immobilization rate and the surface coverage on functionalized regenerated cellulose membranes were studied as a function of biomolecule concentration. Results indicated that the saturation coverage of BSA and protein G was concentration independent (immobilized protein amount of 2.40±0.03mg/g and 2.65±0.07mg/g, respectively). Otherwise, a different immobilization kinetics trend was obtained for lipase, for which the immobilized amount increases as a function of time without reaching a saturation value. Atomic force microscopy (AFM) micrographs showed the formation of monolayers for both BSA and protein G on the membrane surface, while a multilayer structure is found for lipase, in agreement with the trends observed in the related immobilization kinetics. As a result, the morphology of the proteins layer on the membrane surface seems to be strictly dependent on the proteins behavior in solution. Besides, the surface coverage has been described for BSA and protein G by the pseudo second order models, the results indicating the surface reaction as the controlling step of immobilization kinetics. Finally, enzyme activity and binding capacity studies indicated the preservation of the biomolecule functional properties. PMID:27022871

  18. Properties of surface waves in granular media under gravity

    International Nuclear Information System (INIS)

    Acoustical waves propagating along the free surface of granular media under gravity are investigated in the framework of elasticity theory. The influence of stress on a surface wave is analyzed. The results have shown that two types of surface waves, namely sagittal and transverse modes exist depending on initial stress states, which may have some influence on the dispersion relations of surface waves, but the influence is not great. Considering that the present experimental accuracy is far from distinguishing this detail, the validity of elasticity theory on the surface waves propagating in granular media can still be maintained. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. Anti-wear properties on 20CrMnTi steel surfaces with biomimetic non-smooth units

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In order to gain a sufficient wear resistance for applications, the biomimetic non-smooth units in concave were fabricated on the surfaces of 20CrMnTi steel using a biomimetic laser remelting technology. The diameter and distribution of the concaves were optimized using orthogonal experiment. The microstructures of the biomimetic non-smooth units were examined. The anti-wear behaviors were investigated by the rolling wear test with lubricant. The results of wear tests indicated that the biomimetic surfaces exhibit a higher anti-wear ability than the smooth surfaces. The biomimetic surface with concaves of 250 μm in diameter and transverse distance of 270 μm and longitudinal distance of 400 μm exhibits the best anti-wear property. The enhancement of wear resistance can be mainly attributed to the action of biomimetic non-smooth units and the super fined microstructure and hardness in the biomimetic unit zones.

  20. Specific surface area behavior of a dissolving population of particles. Augmenting Mercer Dissolution Theory

    International Nuclear Information System (INIS)

    Specific surface area (Sp) measurements were made on two uranium oxide aerosol materials before and after in vitro dissolution studies were performed on the materials. The results of these Sp measurements were evaluated relative to predictions made from extending Mercer dissolution theory to describe the Sp behavior of a dissolving population of particles

  1. Influences of chemical aging on the surface morphology and crystallization behavior of basaltic glass fibers

    DEFF Research Database (Denmark)

    Lund, Majbritt Deichgræber; Yue, Yuanzheng

    2008-01-01

    The impact of aging in high humidity and water on the surface morphology and crystallization behavior of basaltic glass fibers has been studied using scanning electron microscopy, transmission electron microscopy, calorimetry and X-ray diffraction. The results show that interaction between the...

  2. Research on the behavior of liquid fluids atop superhydrophobic gas-bubbled surfaces

    CERN Document Server

    Lehmann, Gerrit C; Horsch, Martin; Huang, Yow-Lin; Miroshnichenko, Svetlana; Pflock, Rüdiger; Sonnenrein, Gerrit; Vrabec, Jadran

    2010-01-01

    Superhydrophobic surfaces play an important role in the development of new product coatings such as cars, but also in mechanical engineering, especially design of turbines and compressors. Thus a vital part of the design of these surfaces is the computational simulation of such with a special interest on variation of shape and size of minor pits grooved into plane surfaces. In the present work, the dependence of the contact angle on the fluid-wall dispersive energy is determined by molecular simulation and static as well as dynamic properties of unpolar fluids in contact with extremely rough surfaces are obtained.

  3. Surface modification of Fe2O3 nanoparticles with 3-aminopropyltrimethoxysilane (APTMS): An attempt to investigate surface treatment on surface chemistry and mechanical properties of polyurethane/Fe2O3 nanocomposites

    International Nuclear Information System (INIS)

    Highlights: • Surface treatment of Fe2O3 with amino propyl tri methoxy silane. • The surface chemistry pigments were affected by the chemical treatment. • Surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. • The improvement was most pronounced when the nanoparticles were modified with 3 gr silane/5 g nanoparticles. - Abstract: Fe2O3 nanoparticles were modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Modified and unmodified nanoparticles were introduced into the polyurethane matrix at different concentrations. Fourier transform infrared radiation (FT-IR) and X-ray photoelectron spectrophotometer (XPS) were employed in order to investigate the APTMS grafting on the nanoparticles field emission-scanning electron microscope (FE-SEM) was utilized in order to investigate nanoparticles dispersion in the polyurethane coating matrix as well as the fracture behavior of the nanocomposites. The mechanical properties of the nanocomposites were investigated by dynamic mechanical thermal analysis (DMTA) and tensile test. The FTIR spectra and XPS analysis clearly showed that APTMS was grafted on the surface of nanoparticles successfully and formed chemical bonds with the surface. Also, surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. The improvement was most pronounced when the nanoparticles were modified with 3 gr silane/5 g nanoparticles

  4. Surface modification of Fe{sub 2}O{sub 3} nanoparticles with 3-aminopropyltrimethoxysilane (APTMS): An attempt to investigate surface treatment on surface chemistry and mechanical properties of polyurethane/Fe{sub 2}O{sub 3} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Palimi, M.J. [Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of); Rostami, M., E-mail: rostami-m@icrc.ac.ir [Department of Nanomaterials and Nanocoatings, Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of); Mahdavian, M.; Ramezanzadeh, B. [Department of Surface Coatings and Corrosion, Institute for Color Science and Technology (ICST), PO 16765-654, Tehran (Iran, Islamic Republic of)

    2014-11-30

    Highlights: • Surface treatment of Fe{sub 2}O{sub 3} with amino propyl tri methoxy silane. • The surface chemistry pigments were affected by the chemical treatment. • Surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. • The improvement was most pronounced when the nanoparticles were modified with 3 gr silane/5 g nanoparticles. - Abstract: Fe{sub 2}O{sub 3} nanoparticles were modified with various amounts of 3-amino propyl trimethoxy silane (APTMS). Modified and unmodified nanoparticles were introduced into the polyurethane matrix at different concentrations. Fourier transform infrared radiation (FT-IR) and X-ray photoelectron spectrophotometer (XPS) were employed in order to investigate the APTMS grafting on the nanoparticles field emission-scanning electron microscope (FE-SEM) was utilized in order to investigate nanoparticles dispersion in the polyurethane coating matrix as well as the fracture behavior of the nanocomposites. The mechanical properties of the nanocomposites were investigated by dynamic mechanical thermal analysis (DMTA) and tensile test. The FTIR spectra and XPS analysis clearly showed that APTMS was grafted on the surface of nanoparticles successfully and formed chemical bonds with the surface. Also, surface treatment of the nanoparticles by silane resulted in the significant improvement of the mechanical properties of the polyurethane coating. The improvement was most pronounced when the nanoparticles were modified with 3 gr silane/5 g nanoparticles.

  5. Surface behavior of apolipoprotein A-I and its deletion mutants at model lipoprotein interfaces

    OpenAIRE

    Wang, Libo; Mei, Xiaohu; Atkinson, David; Small, Donald M.

    2014-01-01

    Apolipoprotein A-I (apoA-I) has a great conformational flexibility to exist in lipid-free, lipid-poor, and lipid-bound states during lipid metabolism. To address the lipid binding and the dynamic desorption behavior of apoA-I at lipoprotein surfaces, apoA-I, Δ(185-243)apoA-I, and Δ(1-59)(185-243)apoA-I were studied at triolein/water and phosphatidylcholine/triolein/water interfaces with special attention to surface pressure. All three proteins are surface active to both interfaces lowering th...

  6. Improved Fatigue Behavior of Pipeline Steel Welded Joint by Surface Mechanical Attrition Treatment (SMAT)

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Min Huang; Lei Zhou; Zhixin Cong; Huilin Gao

    2009-01-01

    A pipeline steel X80 with welded joint was subjected to surface mechanical attrition treatment (SMAT). After SMAT, a nanostructure surface layer with an average grain size of about 10 nm was formed in the treated sample, and the fatigue limit of the welded joint was elevated by about 13% relative to the untreated joints. In the low and the high amplitude stress regimes, both fatigue strength and fatigue life were enhanced. Formation of the nanostructured surface layer played more important role in the enhanced fatigue behavior than that of residual stress induced by the SMAT.

  7. Dynamic Surface Properties of Asphaltenes and Resins at the Oil-Air Interface.

    Science.gov (United States)

    Bauget, Fabrice; Langevin, Dominique; Lenormand, Roland

    2001-07-15

    Because of the existence of large reserves, the production of heavy oils is presently the object of much interest. Some heavy oil reservoirs show anomalous behavior in primary production, with rates of production better than predicted. In Canada and Venezuela some heavy oils are produced in the form of "bubbly" oil, which is stable for several hours in open vessels. These crude oils are therefore commonly called "foamy oils". Since the presence of bubbles could be responsible for an enhanced rate of production, a better knowledge of the properties of the gas-oil interface is desirable. We have experimentally studied the effect of concentration of asphaltenes and resins on static and dynamic properties of oil-air interfaces and also on bulk viscosity. The experiments include surface tension measurements using the pendant-drop method, surface viscosity by the oscillating-drop method, foamability by continuous gas injection, and film lifetime. All the experiments were performed using resins and asphaltenes in toluene solutions at 20 degrees C. At first asphaltenes enhance foamability and film lifetime. All the experiments performed showed a change in regime for asphaltene concentrations around 10% by weight, possibly due to clustering. At the studied concentrations, the adsorption process at the air-oil interface is not diffusion controlled but rather involves a reorganization of asphaltene molecules in a network structure. The formation of a solid skin is well identified by the increase of the elastic modulus. This elastic modulus is also an important property for foam stability, since a rigid interface limits bubble rupture. The interface rigidity at long times decreases with increases in resin fraction, which could decrease foam stability as well as emulsion stability. Copyright 2001 Academic Press. PMID:11427016

  8. PROPERTIES AND BEHAVIOR OF 238PU RELEVANT TO DECONTAMINATION OF BUILDING 235-F

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, A.; Kane, M.

    2009-11-24

    This report was prepared to document the physical, chemical and radiological properties of plutonium oxide materials that were processed in the Plutonium Fuel Form Facility (PuFF) in building 235-F at the Savannah River Plant (now known as the Savannah River Site) in the late 1970s and early 1980s. An understanding of these properties is needed to support current project planning for the safe and effective decontamination and deactivation (D&D) of PuFF. The PuFF mission was production of heat sources to power Radioisotope Thermoelectric Generators (RTGs) used in space craft. The specification for the PuO{sub 2} used to fabricate the heat sources required that the isotopic content of the plutonium be 83 {+-} 1% Pu-238 due to its high decay heat of 0.57 W/g. The high specific activity of Pu-238 (17.1 Ci/g) due to alpha decay makes this material very difficult to manage. The production process produced micron-sized particles which proved difficult to contain during operations, creating personnel contamination concerns and resulting in the expenditure of significant resources to decontaminate spaces after loss of material containment. This report examines high {sup 238}Pu-content material properties relevant to the D&D of PuFF. These relevant properties are those that contribute to the mobility of the material. Physical properties which produce or maintain small particle size work to increase particle mobility. Early workers with {sup 238}PuO{sub 2} felt that, unlike most small particles, Pu-238 oxide particles would not naturally agglomerate to form larger, less mobile particles. It was thought that the heat generated by the particles would prevent water molecules from binding to the particle surface. Particles covered with bound water tend to agglomerate more easily. However, it is now understood that the self-heating effect is not sufficient to prevent adsorption of water on particle surfaces and thus would not prevent agglomeration of particles. Operational

  9. Optical properties of single semiconductor nanowires and nanowire ensembles. Probing surface physics by photoluminescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pfueller, Carsten

    2011-06-27

    This thesis presents a detailed investigation of the optical properties of semiconductor nanowires (NWs) in general and single GaN NWs and GaN NW ensembles in particular by photoluminescence (PL) spectroscopy. NWs are often considered as potential building blocks for future nanometer-scaled devices. This vision is based on several attractive features that are generally ascribed to NWs. For instance, they are expected to grow virtually free of strain and defects even on substrates with a large structural mismatch. In the first part of the thesis, some of these expectations are examined using semiconductor NWs of different materials. On the basis of the temperature-dependent PL of Au- and selfassisted GaAs/(Al,Ga)As core-shell NWs, the influence of foreign catalyst particles on the optical properties of NWs is investigated. For the Au-assisted NWs, we find a thermally activated, nonradiative recombination channel, possibly related to Auatoms incorporated from the catalyst. These results indicate the limited suitability of catalyst-assisted NWs for optoelectronic applications. The effect of the substrate choice is studied by comparing the PL of ZnO NWs grown on Si, Al{sub 2}O{sub 3}, and ZnO substrates. Their virtually identical optical characteristics indicate that the synthesis of NWs may indeed overcome the constraints that limit the heteroepitaxial deposition of thin films. The major part of this thesis discusses the optical properties of GaN NWs grown on Si substrates. The investigation of the PL of single GaN NWs and GaN NW ensembles reveals the significance of their large surface-to-volume ratio. Differences in the recombination behavior of GaNNW ensembles and GaN layers are observed. First, the large surface-to-volume ratio is discussed to be responsible for the different recombination mechanisms apparent in NWs. Second, certain optical features are only found in the PL of GaN NWs, but not in that of GaN layers. An unexpected broadening of the donor

  10. Properties and behavior of quartz for the silicon process

    Energy Technology Data Exchange (ETDEWEB)

    Aasly, Kurt

    2008-07-01

    This PhD-thesis is a result of the study on important properties of quartz as a raw material for the metallurgical production of ferrosilicon and silicon metal. This includes defining mechanical properties important for the size reduction experienced during transport and storage and thermo-mechanical properties of quartz that is important for how the quartz reacts to the high temperatures experienced as it is charged on the furnace. Additionally, softening properties of quartz have been briefly discussed in some of the papers. Another important goal has been to test analytical and experimental methods for investigating the various properties. The investigations of important factors for the mechanical properties of ores and industrial minerals have been carried out as a literature study. The mining operation and transport from mine to smelter has been discussed and several factors that are significant for achieving best possible mechanical properties of the quartz have been identified. The most important factors are related to production in the mine and processing plant, which should be carefully planned to minimize the amount of blast-induced damage in the rock and thus achieve the best possible mechanical strength of the raw material. The amount of fines can be minimized by controlling the handling of the raw materials during the transport and storage. It is especially important to avoid high drops, both high single drops and accumulated height of all the drops in total. Investigations of the thermo-mechanical properties of quartz have been carried out by using different experimental and characterization methods. The petrographic investigations of the raw materials by polarized light microscopy have been important. Thermo-mechanical investigations have been high-temperature microthermometry and shock heating of quartz samples in an induction furnace with subsequent investigations of the heated material. The subsequent investigation included polarized- and

  11. Preparation, properties and ion-exchange behavior of stannic silicomolybdate

    International Nuclear Information System (INIS)

    The ion-exchange properties of stannic silicomolybdate were studied using the batch method. Preparation of stannic silicomolybdate is shown. The sorbent is stable in water and diluted mineral acids. X-ray diffraction study shows amorphous structure and chemical analysis was performed. The ion-exchange capacities for alkali metals and strontium cations were determined by using fotometric measurements and chemical analyses of the equilibrated exchangers by atomic absorption. The tow techniques showed similar results which revealed that the capacities was changed in values and orders with the changing of the preparation method of the exchangers. The exchangers showed high selectivity for cesium and strontium cations. The results showed decreasing of Kd with increasing of the concentration of ion-exchanger. Also the effect of nitrate anions was investigated by studying the distribution coefficients in nitrate media. The results showed that nitrate anion from nitric acid or ammonium nitrate, led to decrease the distribution coefficients. The results obtained reveal that the properties of the exchangers is slightly changed with the change of the conditions of preparation but the general behaviour of Cs+ and Sr++ cations almost remain the same. Also nitrate solution can be used to reextract these cations from the exchangers. 4 tabs

  12. Investigations of the Electronic Properties and Surface Structures of Aluminium-Rich Quasicrystalline Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Jason A. Barrow

    2003-08-05

    equations. Transport behavior is described in terms of charge carriers and the mean-free time between carrier collisions. It is concluded that the mean-free time is much longer in the periodic direction than in the aperiodic direction. This difference produces the observed anisotropy in thermal transport. The third study presented a detailed analysis of the reversible, sputter-induced phase transformation which occurs on the 5-fold surface of an icosahedral Al-Cu-Fe quasicrystal. Reflection high-energy electron diffraction (RHEED), x-ray photoemission spectroscopy (XPS), and ultra-violet photoemission spectroscopy (UPS) data were collected as a function of annealing temperature and were used to probe surface structure, surface composition, and electronic structure, respectively. The composition and structure of the sputtered surface are consistent with a transformation to the {beta}-Al-Cu-Fe cubic structure, and shows a sharp metallic cut-off in the spectral intensity of the electronic structure at the Fermi edge. Upon annealing the surface reverts to a quasicrystalline composition and structure. This transformation has been correlated with a reduction in the spectral intensity of the electronic structure at the Fermi level. This data clearly demonstrates that the observed reduction is intrinsic to a quasicrystalline surface. It is concluded that this is due to the opening of a pseudo-gap in the electronic density of states as the surface reverts from {beta}-Al-Cu-Fe to quasicrystalline.

  13. Distinct surface hydration behaviors of boron-rich boride thin film coatings

    International Nuclear Information System (INIS)

    In this work, the surface boron chemical states and surface hydration behaviors of the as-deposited and annealed boron-rich boride thin film coatings, including AlMgB14, TiB2 and AlMgB14–TiB2, were systematically studied by use of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The XPS results indicate that boron at annealed AlMgB14 film surface can be oxidized; surprisingly, such oxidation does not lead to the formation of boric acid in ambient air. Instead, boric acid can be produced at the surface of annealed TiB2 film and AlMgB14–TiB2 film. It is shown, via the water contact angle measurements, that these boride films exhibit distinct surface wettability characteristics, which are believed to result in the observed surface hydration processes. Furthermore, we found anatase TiO2 formation plays a major role in the surface wetting behaviors for these boride films

  14. Distinct surface hydration behaviors of boron-rich boride thin film coatings

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Xinhong [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Liu, Wei [Institute of Crystal Materials, Shandong University, Jinan 250100 (China); Ouyang, Jun [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China); Tian, Yun, E-mail: ytian@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education and School of Materials Science and Engineering, Shandong University, Jinan 250061 (China)

    2014-08-30

    In this work, the surface boron chemical states and surface hydration behaviors of the as-deposited and annealed boron-rich boride thin film coatings, including AlMgB{sub 14}, TiB{sub 2} and AlMgB{sub 14}–TiB{sub 2}, were systematically studied by use of X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The XPS results indicate that boron at annealed AlMgB{sub 14} film surface can be oxidized; surprisingly, such oxidation does not lead to the formation of boric acid in ambient air. Instead, boric acid can be produced at the surface of annealed TiB{sub 2} film and AlMgB{sub 14}–TiB{sub 2} film. It is shown, via the water contact angle measurements, that these boride films exhibit distinct surface wettability characteristics, which are believed to result in the observed surface hydration processes. Furthermore, we found anatase TiO{sub 2} formation plays a major role in the surface wetting behaviors for these boride films.

  15. Intrinsic surface-drying properties of bioadhesive proteins.

    Science.gov (United States)

    Akdogan, Yasar; Wei, Wei; Huang, Kuo-Ying; Kageyama, Yoshiyuki; Danner, Eric W; Miller, Dusty R; Martinez Rodriguez, Nadine R; Waite, J Herbert; Han, Songi

    2014-10-13

    Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-water diffusivity, different mussel foot proteins were found to have different abilities to evict hydration layers from surfaces-a necessary step for adsorption and adhesion. It was anticipated that DOPA would mediate dehydration owing to its efficacy in bioinspired wet adhesion. Instead, hydrophobic side chains were found to be a critical component for protein-surface intimacy. This direct measurement of interfacial water dynamics during force-free adsorptive interactions at solid surfaces offers guidance for the engineering of wet adhesives and coatings. PMID:25168789

  16. Osteoblast behavior on various ultra short pulsed laser deposited surface coatings

    International Nuclear Information System (INIS)

    Ultra short pulsed laser deposition technique was utilized to create amorphous diamond, alumina and carbon nitride, and two different titania coatings on silicon wafers, thus producing five different surface deposited films with variable physico-chemical properties. The surface characterizations, including the roughness, the contact angle and the zeta potential measurements were performed before we tested the growth properties of human osteoblast-like Saos-2 cells on these surfaces (three separate experiments). The average roughness and hydrophobicity were the highest on titania-deposited surfaces, while carbon nitride was the most hydrophilic one. Osteoblasts on all surfaces showed a flattened, spread-out morphology, although on amorphous diamond the cell shape appeared more elongated than on the other surfaces. On rough titania, the area covered by the osteoblasts was smaller than on the other ones. Cell proliferation assay did not show any statistically significant differences. - Highlights: ► Variable coatings were made on silicon by using ultra short pulsed laser deposition. ► Coating character modulated physico-chemical surface properties. ► The osteoblast adhesion was smallest on hydrophobic rough TiO2

  17. Chemical properties of surface peat on forest land in Estonia

    Directory of Open Access Journals (Sweden)

    R. Kõlli

    2010-10-01

    Full Text Available The chemical properties of surface peat cover (SPC were studied in the context of Estonian pedoecological conditions. SPC comprises the superficial layers of fens (Group 1 and transitional bogs (Group 2, together with slightly acid peaty mull / strongly acid peaty moder (Group 3 and very strongly acid peaty mor (Group 4 layers overlying mineral soils. Thus, it spans organic soils, namely Histosols (Groups 1 and 2; together with Histic Gleysols (Group 3 and Histic Podzols (Group 4, which are developmentally intermediate between organic and mineral soils. Moderately acid eutrophic (Group 1 and very strongly acid mesotrophic (Group 2 peats (forest litter layers excluded were uniformly characterised up to 40 cm depth; whereas for Groups 3 and 4 we examined the full thickness of available peat layers, which ranged from 10 to 30 cm. The results show that Al, K and heavy metal contents are significantly higher and organic carbon content is lower in Histic Soils (3, 4 than in Histosols (1, 2. The amounts of Ca, Mg, Mn and Fe are significantly higher and C:N ratio, exchangeable acidity and content of free H+ lower in less acidic (1, 3 than in more acidic (2, 4 soil types. The total concentration of elements (excluding heavy metals extracted by nitro-hydrochloric acid (aqua regia is considerably higher in less acidic soils, at 28–45 g kg-1 (1, 3 versus 10–12 g kg-1 (2, 4; and mean contents of individual elements decrease in the order Ca(51% > Fe(20% > S(10% ≥ Al(10% > Mg(3% ≥ P(3% > K(2% > Mn(1% > Na(<1%. The most abundant heavy metals are Pb (12–33 mg kg-1, Zn (7–41 mg kg-1, Cu (3–12 mg kg-1, Cr (2–23 mg kg-1 and Ni (2–8 mg kg-1; Cd and Hg contents are very low, ranging from 0.2 to 0.5 mg kg-1. The dominant exchangeable basic cations are Ca2+ (78–93% and Mg2+ (7–15%, and the peat contains much smaller amounts of K+ (1–6% and Na+ (<2%. The total exchangeable acidic cations (1–14 cmol kg-1 are dominated by H+ (51–83% and Al3

  18. SURFACE PROPERTIES AND MODELLING POTENTIOMETRIC TITRATION OF AQUEOUS ILLITE SUSPENSIONS

    OpenAIRE

    Kriaa, A.; Hamdi, N.; Srasra, E.

    2008-01-01

    Potentiometric titration behaviour of complex illitic clay minerals, provided from different origins (two Tunisian illite samples and an American illite sample), were investigated and interpreted according to surface complexation theory. In the present investigation, the focus was on the surface charge characteristics. Proton surface charge can be calculated by subtracting supernatant titration curves from those of illite suspension at ambient temperature and aerated medium. The points of zer...

  19. Intrinsic Surface-Drying Properties of Bio-adhesive Proteins

    OpenAIRE

    Akdogan, Yasar; Wei, Wei; Huang, Kuo-Ying; Kageyama, Yoshiyuki; Danner, Eric W.; Miller, Dusty R.; Martinez Rodriguez, Nadine R.; Herbert Waite, J.; Han, Songi

    2014-01-01

    Sessile marine mussels must “dry” underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bio-inspired adhesion have largely been performed under applied compressive forces but these are poor predictors of an adhesive’s ability to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction via the surface water diffusivity, different mussel foot proteins were f...

  20. Intrinsic surface-drying properties of bioadhesive proteins

    OpenAIRE

    Akdogan, Y; Wei, W.; Huang, KY; Kageyama, Y.; Danner, EW; Miller, DR; Martinez Rodriguez, NR; Waite, JH; Han, S.

    2014-01-01

    © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-wat...

  1. Intrinsic surface-drying properties of bioadhesive proteins

    OpenAIRE

    Akdogan, Y; Wei, W.; Huang, KY; Kageyama, Y.; Danner, EW; Miller, DR; Martinez Rodriguez, NR; Waite, JH; Han, S.

    2014-01-01

    Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-water diffusivity, different mussel foot pro...

  2. Effects of engineered nano-titanium dioxide on pore surface properties and phosphorus adsorption of sediment: Its environmental implications

    International Nuclear Information System (INIS)

    Highlights: → The attachment of Enano-TiO2 to surface enhanced markedly sediment BET surface area and t-Plot external surface area. → The fill of Enano-TiO2 into the micropores reduced significantly the sediment t-Plot micropore surface area. → Enano-TiO2 could increase sediment phosphorus (P) adsorption maximum and decrease in sediment P binding energy. → P would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO2. - Abstract: Understanding the environmental safety and human health implications of engineered nanoparticles (ENPs) is of worldwide importance. As an important ENPs, engineered nano-TiO2 (Enano-TiO2) may have been substantially deposited in aquatic sediments because of its widely uses. Sediment pore surface properties would be thus significantly influenced due to the large surface area of Enano-TiO2. In this study, Enano-TiO2 was found to greatly impact on sediment pore surface properties. The attachment of Enano-TiO2 particles to sediment surfaces enhanced markedly BET specific surface area and t-Plot external specific surface area, and thereby increased sediment phosphorus (P) adsorption maximum (Smax). Contrarily, the fill of Enano-TiO2 particles into the micropores of sediments could significantly reduce t-Plot micropore specific surface area, and cause slight decrease in sediment P binding energy (K). Clearly, P sorbed in sediment would be easily released because of the decreasing P binding energy of the sediment with elevated Enano-TiO2. Enano-TiO2 would thus cause aggravated endogenous pollution in water if such sediment was re-suspended on disturbance. The results obtained in this study contribute to our increasing knowledge of how to regulate physicochemical behavior of pollutants in sediments under the influences of Enano-TiO2 and/or similar ENPs.

  3. Effect of Surface Stress Mitigation on the Corrosion Behavior of Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    Fix, D V; Yilmaz, A; Wong, L L; Estill, J C; Rebak, R B

    2004-11-10

    When metallic plates are welded, for example using the Gas Tungsten Arc Welding (GTAW) process, residual tensile stresses may develop in the vicinity of the weld seam. Processes such as Low Plasticity Burnishing (LPB) and Laser Shock Peening (LSP) could be applied locally to eliminate the residual stresses produced by welding. In this study, Alloy 22 (N06022) plates were welded and then the above-mentioned surface treatments were applied to eliminate the residual tensile stresses. The aim of the current study was to comparatively test the corrosion behavior of as-welded (ASW) plates with the corrosion behavior of plates with stress mitigated surfaces. Immersion and electrochemical tests were performed. Results from both general and localized corrosion tests show that the corrosion resistance of the mitigated plates was not affected by the surface treatments applied.

  4. Surface chemistry and friction behavior of the silicon carbide (0001) surface at temperatures to 1500 deg C

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1981-01-01

    X-ray photoelectron and Auger electron spectroscopy analyses and friction studies were conducted with a silicon carbide (0001) surface in contact with iron at various temperatures to 1200 or 1500 C in a vacuum of 10 to the minus 8th power Pa. The results indicate that there is a significant temperature influence on both the surface chemistry and friction properties of silicon carbide. The principal contaminant of adsorbed amorphous carbon on the silicon carbide surface in the as received state is removed by simply heating to 400 C. Above 400 C, graphite and carbide type carbine are the primary species on the silicon carbide surface, in addition to silicon. The coefficients of friction of polycrystalline iron sliding against a single crystal silicon carbide (0001) surface were high at temperatures to 800 C. Similar coefficients of friction were obtained at room temperature after the silicon carbide was preheated at various temperatures up 800 C. When the friction experiments were conducted above 800 C or when the specimens were preheated to above 800 C, the coefficients of friction were dramatically lower. At 800 C the silicon and carbide type carbon are at a maximum intensity in the XPS spectra. With increasing temperature above 800 C, the concentration of the graphite increases rapidly on the surface, whereas those of the carbide type carbon and silicon decrease rapidly.

  5. Effect of surface preparation on corrosion properties and nickel release of a NiTi alloy

    Institute of Scientific and Technical Information of China (English)

    MIAO Weidong; MI Xujun; XU Guodong; LI Huachu

    2006-01-01

    Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys.The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied.Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system.Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed.Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.

  6. Effect of nanocoating with rhamnogalacturonan-I on surface properties and osteoblasts response

    DEFF Research Database (Denmark)

    Gurzawska, Katarzyna Aleksandra; Svava, Rikke; Syberg, Susanne;

    2012-01-01

    -I) on surface properties and osteoblasts response. Three different RG-Is from apple and lupin pectins were modified and coated on amino-functionalized tissue culture polystyrene plates (aminated TCPS). Surface properties were evaluated by scanning electron microscopy, contact angle measurement, atomic force...

  7. Mechanical properties and failure behavior of unidirectional porous ceramics

    Science.gov (United States)

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

    2016-04-01

    We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45–80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

  8. ODMBP: Behavior Forwarding for Multiple Property Destinations in Mobile Social Networks

    Directory of Open Access Journals (Sweden)

    Jia Xu

    2016-01-01

    Full Text Available The smartphones are widely available in recent years. Wireless networks and personalized mobile devices are deeply integrated and embedded in our lives. The behavior based forwarding has become a new transmission paradigm for supporting many novel applications. However, the commodities, services, and individuals usually have multiple properties of their interests and behaviors. In this paper, we profile these multiple properties and propose an Opportunistic Dissemination Protocol based on Multiple Behavior Profile, ODMBP, in mobile social networks. We first map the interest space to the behavior space and extract the multiple behavior profiles from the behavior space. Then, we propose the correlation computing model based on the principle of BM25 to calculate the correlation metric of multiple behavior profiles. The correlation metric is used to forward the message to the users who are more similar to the target in our protocol. ODMBP consists of three stages: user initialization, gradient ascent, and group spread. Through extensive simulations, we demonstrate that the proposed multiple behavior profile and correlation computing model are correct and efficient. Compared to other classical routing protocols, ODMBP can significantly improve the performance in the aspect of delivery ratio, delay, and overhead ratio.

  9. Automated Surface Classification of SRF Cavities for the Investigation of the Influence of Surface Properties onto the Operational Performance

    Energy Technology Data Exchange (ETDEWEB)

    Wenskat, Marc

    2015-07-15

    Superconducting niobium radio-frequency cavities are fundamental for the European XFEL and the International Linear Collider. To use the operational advantages of superconducting cavities, the inner surface has to fulfill quite demanding requirements. The surface roughness and cleanliness improved over the last decades and with them, the achieved maximal accelerating field. Still, limitations of the maximal achieved accelerating field are observed, which are not explained by localized geometrical defects or impurities. The scope of this thesis is a better understanding of these limitations in defect free cavities based on global, rather than local, surface properties. For this goal, more than 30 cavities underwent subsequent surface treatments, cold RF tests and optical inspections within the ILC-HiGrade research program and the XFEL cavity production. An algorithm was developed which allows an automated surface characterization based on an optical inspection robot. This algorithm delivers a set of optical surface properties, which describes the inner cavity surface. These optical surface properties deliver a framework for a quality assurance of the fabrication procedures. Furthermore, they shows promising results for a better understanding of the observed limitations in defect free cavities.

  10. Automated Surface Classification of SRF Cavities for the Investigation of the Influence of Surface Properties onto the Operational Performance

    International Nuclear Information System (INIS)

    Superconducting niobium radio-frequency cavities are fundamental for the European XFEL and the International Linear Collider. To use the operational advantages of superconducting cavities, the inner surface has to fulfill quite demanding requirements. The surface roughness and cleanliness improved over the last decades and with them, the achieved maximal accelerating field. Still, limitations of the maximal achieved accelerating field are observed, which are not explained by localized geometrical defects or impurities. The scope of this thesis is a better understanding of these limitations in defect free cavities based on global, rather than local, surface properties. For this goal, more than 30 cavities underwent subsequent surface treatments, cold RF tests and optical inspections within the ILC-HiGrade research program and the XFEL cavity production. An algorithm was developed which allows an automated surface characterization based on an optical inspection robot. This algorithm delivers a set of optical surface properties, which describes the inner cavity surface. These optical surface properties deliver a framework for a quality assurance of the fabrication procedures. Furthermore, they shows promising results for a better understanding of the observed limitations in defect free cavities.

  11. Basic surface properties of mononuclear cells from Didelphis marsupialis.

    Science.gov (United States)

    Nacife, V P; de Meirelles, M de N; Silva Filho, F C

    1998-01-01

    The electrostatic surface charge and surface tension of mononuclear cells/monocytes obtained from young and adult marsupials (Didelphis marsupialis) were investigated by using cationized ferritin and colloidal iron hydroxyde, whole cell electrophoresis, and measurements of contact angles. Anionic sites were found distributed throughout the entire investigated cell surfaces. The results revealed that the anionic character of the cells is given by electrostatic charges corresponding to -18.8 mV (cells from young animals) and -29.3 mV (cells from adult animals). The surface electrostatic charge decreased from 10 to 65.2% after treatment of the cells with each one of trypsin, neuraminidase and phospholipase C. The hydrophobic nature of the mononuclear cell surfaces studied by using the contact angle method revealed that both young and adult cells possess cell surfaces of high hidrofilicity since the angles formed with drops of saline water were 42.5 degrees and 40.8 degrees, respectively. Treatment of the cells with trypsin or neuraminidase rendered their surfaces more hydrophobic, suggesting that sialic acid-containing glycoproteins are responsible for most of the hydrophilicity observed in the mononuclear cell surfaces from D. marsupialis. PMID:9921307

  12. Basic Surface Properties of Mononuclear Cells from Didelphis marsupialis

    Directory of Open Access Journals (Sweden)

    Nacife Valéria Pereira

    1998-01-01

    Full Text Available The electrostatic surface charge and surface tension of mononuclear cells/monocytes obtained from young and adult marsupials (Didelphis marsupialis were investigated by using cationized ferritin and colloidal iron hydroxyde, whole cell electrophoresis, and measurements of contact angles. Anionic sites were found distributed throughout the entire investigated cell surfaces. The results revealed that the anionic character of the cells is given by electrostatic charges corresponding to -18.8 mV (cells from young animals and -29.3 mV (cells from adult animals. The surface electrostatic charge decreased from 10 to 65.2% after treatment of the cells with each one of trypsin, neuraminidase and phospholipase C. The hydrophobic nature of the mononuclear cell surfaces studied by using the contact angle method revealed that both young and adult cells possess cell surfaces of high hidrofilicity since the angles formed with drops of saline water were 42.5°and 40.8°, respectively. Treatment of the cells with trypsin or neuraminidase rendered their surfaces more hydrophobic, suggesting that sialic acid-containing glycoproteins are responsible for most of the hydrophilicity observed in the mononuclear cell surfaces from D. marsupialis.

  13. Surface properties of aluminum alloy as material for ultrahigh vacuum

    International Nuclear Information System (INIS)

    The characteristics of aluminum alloy (2017 alloy) for the vacuum chambers of TRISTAN were studied. Machining, electric discharge machining and chemical polishing were made successively on the samples of the 2017 alloy. The observation of surface state, the analysis of surface composition and high temperature desorption experiment were performed. The measurement of surface roughness with a probe, the observation with a scanning electron microscope (SEM), and the measurement of surface roughness factor (SRF) were carried out as the study of the surface state. The analysis of surface composition was made by the Auger electron spectrometry. It was found that the surfaces of samples treated by discharge machining were rough and have thick oxide layer. When chemical polishing was applied to these samples, the surfaces became smooth, and the oxide layer became thin. By heating the samples to raise the temperature, the desorption of H2O, CO and CO2 was caused. The amount of desorption was in close relation with the SRF. (Kato, T.)

  14. Prediction of the adhesive behavior of bio-inspired functionally graded materials against rough surfaces

    OpenAIRE

    Chen Peijian; Peng Juan; Zhao Yucheng; Gao Feng

    2014-01-01

    Roughness effect and adhesion properties are important characteristics to be accessed in the development of functionally graded materials for biological and biomimetic applications, particularly for the hierarchical composition in biomimetic gecko robot. A multi-asperities adhesion model to predict the adhesive forces is presented in this work. The effect of surface roughness and graded material properties, which significantly alter the adhesive strength between contact bodies, can be simulta...

  15. Monte Carlo Simulation for Surface Properties of Two-Yukawa Fluids

    Institute of Scientific and Technical Information of China (English)

    刘金晨; 吴畏; 陆九芳; 李以圭

    2002-01-01

    The two-Yukawa (TY) potential is a newly developed potential function for fluids. The Monte Carlo method was used to simulate the potential energy, intermolecular forces, radial distribution function, density profile, surface thickness and surface tension for a TY fluid at different temperatures. The results for a TY fluid are compared to those for a Lennard-Jone fluid, which shows that the surface properties are more sensitive to the intermolecular potential than the bulk properties and the repulsive action with a shore range can also influence the surface properties.

  16. Influence of surface roughness on the corrosion behavior of Alloy 690TT in PWR primary water

    International Nuclear Information System (INIS)

    Highlights: • Surface roughness effect on the corrosion rate of Alloy 690 is provided. • Surface micro-hardness decreased as the roughness value decreased. • Cr-enriched polyhedral oxide particles were formed on the ground surfaces. • Ni-enriched strip-like oxides were formed on the polished surfaces. • Corrosion rate decreased with a decrease in the roughness value. - Abstract: The purpose of this work is to investigate the effect of surface roughness on the corrosion behavior of Alloy 690TT steam generator tube material in simulated primary water at 330 °C. The surface roughness was controlled in the range of 710–25 nm by mechanical grinding and polishing method. Surface hardness gradually decreased with a decrease in the roughness value. Polyhedral oxide particles were formed on the ground surfaces, whereas the mixed oxides of a polyhedral and strip-like type were observed on the polished surface. The corrosion rate decreased by about 64% as the roughness values decreased from 710 to 150 nm. However, no further changes were observed in the range of 150–25 nm

  17. Effects of surface atomistic modification on mechanical properties of gold nanowires

    International Nuclear Information System (INIS)

    Highlights: • Molecular dynamics simulations of surface modification effect of Au nanowires. • Surface modification can greatly affect the mechanical properties of nanowires. • Core–shell model is used to elucidate the effect of residual surface stress. - Abstract: Modulation of the physical and mechanical properties of nanowires is a challenging issue for their technological applications. In this paper, we investigate the effects of surface modification on the mechanical properties of gold nanowires by performing molecular dynamics simulations. It is found that by modifying a small density of silver atoms to the surface of a gold nanowire, the residual surface stress state can be altered, rendering a great improvement of its plastic yield strength. This finding is in good agreement with experimental measurements. The underlying physical mechanisms are analyzed by a core–shell nanowire model. The results are helpful for the design and optimization of advanced nanomaterial with superior mechanical properties

  18. Effects of surface atomistic modification on mechanical properties of gold nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiao-Yu [AML and CNMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072 (China); Xu, Yuanjie [Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072 (China); Wang, Gang-Feng [Department of Engineering Mechanics, Xi' an Jiaotong University, Xi' an 710049 (China); Gu, Yuantong [School of Chemistry, Physics, and Mechanical Engineering, Queensland University of Technology, Brisbane 4001 (Australia); Feng, Xi-Qiao, E-mail: fengxq@tsinghua.edu.cn [AML and CNMM, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China)

    2015-09-18

    Highlights: • Molecular dynamics simulations of surface modification effect of Au nanowires. • Surface modification can greatly affect the mechanical properties of nanowires. • Core–shell model is used to elucidate the effect of residual surface stress. - Abstract: Modulation of the physical and mechanical properties of nanowires is a challenging issue for their technological applications. In this paper, we investigate the effects of surface modification on the mechanical properties of gold nanowires by performing molecular dynamics simulations. It is found that by modifying a small density of silver atoms to the surface of a gold nanowire, the residual surface stress state can be altered, rendering a great improvement of its plastic yield strength. This finding is in good agreement with experimental measurements. The underlying physical mechanisms are analyzed by a core–shell nanowire model. The results are helpful for the design and optimization of advanced nanomaterial with superior mechanical properties.

  19. Miscibility behavior and single chain properties in polymer blends: a bond fluctuation model study

    OpenAIRE

    Mueller, Marcus

    1999-01-01

    Computer simulation studies on the miscibility behavior and single chain properties in binary polymer blends are reviewed. We consider blends of various architectures in order to identify important architectural parameters on a coarse grained level and study their qualitative consequences for the miscibility behavior. The phase diagram, the relation between the exchange chemical potential and the composition, and the intermolecular paircorrelation functions for symmetric blends of linear chai...

  20. Microstructure, tensile properties and fracture behavior of high temperature Al–Si–Mg–Cu cast alloys

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, A.M.A., E-mail: madel@uqac.ca [Center for Advanced Materials, Qatar University, Doha (Qatar); Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez Canal University, Box 43721, Suez (Egypt); Samuel, F.H. [Université du Québec à Chicoutimi, Chicoutimi, QC, Canada G7H 2B1 (Canada); Al Kahtani, Saleh [Industrial Engineering Program, Mechanical Engineering Department, College of Engineering, Salman bin Abdulaziz University, Al Kharj (Saudi Arabia)

    2013-08-10

    The high temperature tensile behavior of 354 aluminum cast alloy was investigated in the presence of Zr and Ni. The cast alloys were given a solutionizing treatment followed by artificial aging at 190 °C for 2 h. High temperature tensile tests were conducted at various temperatures from 25 °C to 300 °C. Optical microscopy and electron probe micro-analyzer were used to study the microstructure of different intermetallic phases formed. The fractographic observations of fracture surface were analyzed by scanning electron microscopy to understand the fracture mechanism. The results revealed that the intermetallics phases of (Al, Si){sub 3}(Zr, Ti), Al{sub 3}CuNi and Al{sub 9}NiFe are the main feature in the microstructures of alloys with Zr and Ni additions. The results also indicated that the tensile strength of alloy decreases with an increase in temperature. The combined addition of 0.2 wt% Zr and 0.2 wt% Ni leads to a 30% increase in the tensile properties at 300 °C compared to the base alloy. Zr and Ni bearing phases played a vital role in the fracture mechanism of the alloys studied.

  1. Scaling behavior and morphological properties of the interfaces obtained by the multilayer deposition process

    International Nuclear Information System (INIS)

    The aim of the present work was to study numerically the scaling behavior and the morphological properties of the interfaces generated by the multilayer deposition process. We have noticed that, in the case where the ratio of the surface diffusion coefficient to the deposition rate reaches high values D/F > > 1, the interface consists of mound structures. By using the dynamic scaling, we have shown that the height–height correlation function scales with time t and length l as G(l,t) ∼ lαf(t/lα/β) with β = 0.25 ± 0.05 and α = 0.51 ± 0.02. These exponent values are equal to the ones predicted by the Edwards–Wilkinson approach. Besides, our results are in agreement with the growth system of Cu/Cu(100) at 300 K which has been characterized in more detail by a combined scanning tunneling microscopy and spot profile analysis — low energy electronic diffusion study. Moreover, by considering two different methods, we have examined the fractal aspect of the obtained interfaces. - Highlights: • The adlayer interfaces present mound morphologies. • The adlayer interfaces scale with the Family–Vicsek law. • The critical exponents (α, β) are in agreement with those of Edwards–Wilkinson approach

  2. Microstructure, tensile properties and fracture behavior of high temperature Al–Si–Mg–Cu cast alloys

    International Nuclear Information System (INIS)

    The high temperature tensile behavior of 354 aluminum cast alloy was investigated in the presence of Zr and Ni. The cast alloys were given a solutionizing treatment followed by artificial aging at 190 °C for 2 h. High temperature tensile tests were conducted at various temperatures from 25 °C to 300 °C. Optical microscopy and electron probe micro-analyzer were used to study the microstructure of different intermetallic phases formed. The fractographic observations of fracture surface were analyzed by scanning electron microscopy to understand the fracture mechanism. The results revealed that the intermetallics phases of (Al, Si)3(Zr, Ti), Al3CuNi and Al9NiFe are the main feature in the microstructures of alloys with Zr and Ni additions. The results also indicated that the tensile strength of alloy decreases with an increase in temperature. The combined addition of 0.2 wt% Zr and 0.2 wt% Ni leads to a 30% increase in the tensile properties at 300 °C compared to the base alloy. Zr and Ni bearing phases played a vital role in the fracture mechanism of the alloys studied

  3. Mesoscale Characterization of Coupled Hydromechanical Behavior of a Fractured Porous Slope in Response to Free Water-Surface Movement

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny; Guglielmi, Y.; Cappa, F.; Rutqvist, J.; Tsang, C.-F.; Thoraval, A.

    2008-05-15

    the high-permeability zones. The periodicity and magnitude of free water-surface movements cause 10 to 20% variations in those local stress/strain accumulations related to the contrasting HM behavior for high and low-permeable elements of the slope. Finally, surface-tilt monitoring coupled with internal localized pressure/deformation measurements appears to be a promising method for characterizing the HM properties and behavior of a slope, and for detecting its progressive destabilization.

  4. Effects of grit blasting on surface properties of steel substrates

    International Nuclear Information System (INIS)

    Low carbon steel substrates have been grit blasted using alumina grits of various sizes under varying pressure, time, angle and standoff distances and the corresponding effect on surface roughness and surface residual stress has been studied. The mechanism of material removal in grit blasting has been analyzed. The effect of blasting process parameters on substrate surface residual stress has been studied using a statistically designed experiment. For this purpose the Barkhausen noise analysis (BNA) of the blasted surface has been undertaken. Then the BNA results have been calibrated against and complemented using the residual stress values measured using X-ray diffraction. The correlation between BN signal and the measured residual stress has been studied. The material removal in blasting takes place by microcutting, indentation or by a mixed mode depending on the blasting angle. During blasting the alumina grits themselves also undergo erosion. The analysis of the experimental results shows that the surface roughness increases with grit size, blasting pressure and to an extent with blasting time and blasting angle as well. The compressive residual stress of the surface and subsurface hardness increases with blasting pressure and blasting angle. The Barkhausen noise signal has a strong correlation with the magnitude of the compressive residual stress on the blasted surface.

  5. Transient Couette flow of a rarefied gas between plane parallel walls with different surface properties

    Science.gov (United States)

    Doi, Toshiyuki

    2016-02-01

    Transient Couette flow of a rarefied gas between plane parallel walls with different surface properties induced by a sudden start-up of one of the walls is studied based on kinetic theory. The linearized Boltzmann equation for a hard sphere molecular gas is analyzed under the assumptions that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary. The initial and boundary value problem is solved numerically by using a modified hybrid scheme of characteristic coordinate and finite difference methods, to describe the discontinuities in the velocity distribution function correctly. The time evolution of the flow and the approach to the final time-independent state are studied over a wide range of the mean free paths and the accommodation coefficient of the boundary. In the transient process, the shear force acting on the moving wall depends on which wall moves. In contrast, the shear force acting on the wall at rest is independent of which wall moves; this property is a consequence of the symmetric relation of the Boltzmann equation [S. Takata, "Symmetry of the unsteady linearized Boltzmann equation in a fixed bounded domain," J. Stat. Phys. 140, 985 (2010)]. The speed of approach to the time-independent state is fastest at an intermediate value of the mean free path. The behavior of the gas in the final time-independent state, including the heat flow in the isothermal gas, is also discussed.

  6. Correlation Between Surface Roughness and Rheological Properties of Liquid Ductile Cast Iron

    Directory of Open Access Journals (Sweden)

    B. Borowiecki

    2012-12-01

    Full Text Available The investigation of filling process of ductile cast iron flow in sand mould was showed the correlation between casting roughness surface and rheological properties of metal. Evidently of castings surface roughness was state of distance, from a few to a dozen diameters of vertical channel inlet. The method of rod fluidity test permit to study of rheological properties of metal and the roughness surface of castings.

  7. Manipulation of fluids in three-dimensional porous photonic structures with patterned surface properties

    Science.gov (United States)

    Aizenberg, Joanna; Burgess, Ian B.; Mishchenko, Lidiya; Hatton, Benjamin; Loncar, Marko

    2016-03-08

    A three-dimensional porous photonic structure, whose internal pore surfaces can be provided with desired surface properties in a spatially selective manner with arbitrary patterns, and methods for making the same are described. When exposed to a fluid (e.g., via immersion or wicking), the fluid can selectively penetrate the regions of the structure with compatible surface properties. Broad applications, for example in security, encryption and document authentication, as well as in areas such as simple microfluidics and diagnostics, are anticipated.

  8. Nanoscale surface properties and interaction with fundamental biomolecules of chlorite and phlogopite

    OpenAIRE

    Moro, Daniele

    2014-01-01

    The surface properties of minerals have important implications in geology, environment, industry and biotechnology and for certain aspects in the research on the origin of life. This research project aims to widen the knowledge on the nanoscale surface properties of chlorite and phlogopite by means of advanced methodologies, and also to investigate the interaction of fundamental biomolecules, such as nucleotides, RNA, DNA and amino acid glycine with the surface of the selected phyllosilica...

  9. Charge behavior on insulating monocrystallic surfaces by Kelvin probe force microscopy

    International Nuclear Information System (INIS)

    Full text: Detailed knowledge on the contact charging behavior of dielectric materials is of great interest for technological applications like tribocharging separation. The underlying mechanisms are still not well understood. The charging of quartz and calcite single crystal surfaces upon contact with an Atomic Force Microscope tip has been investigated using Kelvin Probe Force Microscopy. It turned out that the charging is strongly influenced by the sample history. Especially contact with different forms of water (bulk water or humid air) and sample heat treatment change the charging/discharging behavior significantly. (author)

  10. Impurities and Electronic Property Variations of Natural MoS2 Crystal Surfaces.

    Science.gov (United States)

    Addou, Rafik; McDonnell, Stephen; Barrera, Diego; Guo, Zaibing; Azcatl, Angelica; Wang, Jian; Zhu, Hui; Hinkle, Christopher L; Quevedo-Lopez, Manuel; Alshareef, Husam N; Colombo, Luigi; Hsu, Julia W P; Wallace, Robert M

    2015-09-22

    Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication. PMID:26301428

  11. Dendritic surface functionalization of nanomaterials: controlling properties and functions for biomedical applications

    Directory of Open Access Journals (Sweden)

    Ali Nazemi

    2013-01-01

    Full Text Available A wide variety of nanomaterials have demonstrated promise in medical applications such as drug delivery and imaging. In these applications, the surface chemistry of the materials is critical as it plays an important role in determining the toxicity and biodistribution behavior of the material. We review here the functionalization of nanomaterials with dendrons as an efficient method to alter the surface chemistry of the materials, introducing new properties and functions. Described here is the functionalization of superparamagnetic iron oxide nanoparticles (SPIO with dendritic guanidines to enhance their transport into cells for magnetic resonance imaging applications. The introduction of dendrons bearing peripheral hydroxyls, amines, guanidines, carbohydrates and Gd(III chelates to polymer vesicles (polymersomes is also described. These dendritic moieties allow for modulation of toxicity, cell uptake, protein binding, and contrast agent efficiency, while at the same time allowing the stabilities of the polymersomes to be maintained. Thus, this approach holds promise for the development of a wide range of multifunctional materials for pharmaceutical applications.

  12. Ge Nanoislands Grown by Radio Frequency Magnetron Sputtering: Comprehensive Investigation of Surface Morphology and Optical Properties

    Directory of Open Access Journals (Sweden)

    Alireza Samavati

    2015-01-01

    Full Text Available The comprehensive investigation of the effect of growth parameters on structural and optical properties of Si-based single layer Ge nanoislands grown via Stranski-Krastanov mechanism employing radio frequency magnetron sputtering due to its high deposition rate, easy procedure, economical cost, and safety is carried out. The estimated width and height of Ge nanoislands produced by this technique are in the range of ∼8 to ∼30 and ∼2 to 8 nm, respectively. Varieties parameters are manipulated to optimize the surface morphology and structural and optical behavior of Ge nanoislands. The resulted nanoislands are analyzed using various analytical techniques including atomic force microscope, X-ray diffraction, energy dispersive X-ray spectroscopy, room temperature photoluminescence, and Raman spectroscopy. The optimum parameters for growing high quality samples having high number density and homogenous and small size distribution are found to be 400°C for substrate temperature, 300 sec for deposition time, 10 sccm for Ar flow, and 100 W for radio frequency power. The excellent features of the results suggest that our systematic investigation on the organized growth factors and their effects on surface parameters and photoluminescence emission energy may constitute a basis for the tunable growth of Ge nanoislands (100 nanoislands suitable in nanophotonics.

  13. Material Properties and Tensile Behaviors of Polypropylene Geogrid and Geonet for Reinforcement of Soil Structures

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The properties and tensile behaviors of polypropylene (PP) geogrids and geonets for reinforcement of soil structures are investigated.Mass per unit area of the geogrids and geonets was weighed using an electronic balance and aperture sizes of the geonets were exactly measured using a computer.Laboratory tests were performed using a small tensile machine capable of monitoring tensile force and displacement.Tensile failure behaviors were described,and tensile index properties such as tensile strength,maximum tensile strain,tensile forces corresponding to different strains in the geogrids and gronets were obtained.The characterization of these indexes is discussed.

  14. Erosion properties and dispersion-flocculation behavior of bentonite particles

    International Nuclear Information System (INIS)

    Experimental and theoretical studies have been performed to clarify the ability of flowing groundwater in contact with bentonite to generate bentonite colloidal particles and disperse such colloids. This information is required to determine (a) the long-term stability of bentonite as a buffer material for borehole disposal of radioactive wastes in deep geologic media and (b) the potential influence of bentonite colloidal particles on radionuclide transport, specifically for use in scenario analyses in the performance assessment of waste disposal. In this study, the minimum groundwater velocity required to erode particles of Na-bentonite or Ca-bentonite from a bentonite surface in contact with groundwater was derived from shear strengths of aqueous bentonite gel suspensions, as determined by viscometer tests. The shear strengths were used to estimate the corresponding shear force on bentonite particle-particle bonds, using an estimated value for the number of initial bentonite particle-particle bonds in the experimental systems studied. The derived shear force was converted to corresponding groundwater velocity by using Stokes' equation and simplifying assumptions. The results indicate that groundwater velocities in a range of about 10-5 to 10-4 m/s would be required to initiate bentonite erosion. This range is higher than the groundwater flow velocity generally found in deep geologic media in Japan. In addition, known groundwater electrolyte concentrations were compared with theoretical estimates of aqueous electrolyte concentrations required to flocculate colloidal bentonite particles (for example 1 x 10-3 mol/l Na+). The comparison indicates that, even if erosion of bentonite occurred, the colloidal bentonite particles formed would flocculate. As a result, this study has shown that the effect of bentonite colloids on radionuclide transport is likely to be negligible in the performance assessment of radioactive waste disposal in deep geologic media

  15. An expert system to characterize the surface morphological properties according to their functionalities

    International Nuclear Information System (INIS)

    In this paper we propose a new methodology to characterize the morphological properties of a surface in relation with its functionality (tribological properties, surface coating adhesion, brightness, wettability...). We create a software based on experimental design and surface profile recording. Using an appropriate database structure, the roughness parameters are automatically computed at different scales. The surface files are saved in a hard disk directory and roughness parameters are computed at different scales. Finally, a statistical analysis system proposes the roughness parameter (or the pair of roughness parameters) that better describe(s) the functionality of the surface and the spatial scales at which the parameter(s) is (are) the more relevant.

  16. Investigation of some properties of Nylon-6 surface treated by corona discharge in helium

    International Nuclear Information System (INIS)

    In this work an easy and less expensive method of treatment has been used by corona discharge. This allows to modify the surface properties and especially to improve the compatibility of polymers with biological tissue. The Nylon-6 as a test material was chosen. A scanning electron microscope to visualize the morphology of the morphology of the surface and an IR spectrophotometer able to identify the amide groups and other as well, have been used. Morphology of the treated surface by corona discharge emphasis an etching an etching and/or a crosslinking of amorphous domains, generally important to improve the properties as wetting, dyeing, adhesion, etc. Over all treated surface there is significant blood compatible properties without the need of heparinization of surface. The treated surface influences the biological behaviour of micro-organisms, respectively, that surface is a favourable medium for division of cells and may increase their lifetime. (authors)

  17. Symmetric scaling properties in global surface air temperature anomalies

    Science.gov (United States)

    Varotsos, Costas A.; Efstathiou, Maria N.

    2015-08-01

    We have recently suggested "long-term memory" or internal long-range correlation within the time-series of land-surface air temperature (LSAT) anomalies in both hemispheres. For example, an increasing trend in the LSAT anomalies is followed by another one at a different time in a power-law fashion. However, our previous research was mainly focused on the overall long-term persistence, while in the present study, the upward and downward scaling dynamics of the LSAT anomalies are analysed, separately. Our results show that no significant fluctuation differences were found between the increments and decrements in LSAT anomalies, over the whole Earth and over each hemisphere, individually. On the contrary, the combination of land-surface air and sea-surface water temperature anomalies seemed to cause a departure from symmetry and the increments in the land and sea surface temperature anomalies appear to be more persistent than the decrements.

  18. Irradiation of poly(tetrafluoroethylene) surfaces by CF{sub 4} plasma to achieve robust superhydrophobic and enhanced oleophilic properties for biological applications

    Energy Technology Data Exchange (ETDEWEB)

    Salapare, Hernando S., E-mail: hssalapare@up.edu.ph [Plasma Physics Laboratory, National Institute of Physics, College of Science, University of the Philippines Diliman, Quezon City 1101 (Philippines); eUP Office and UP Information Technology Development Center, University of the Philippines, Quezon City 1101 (Philippines); Suarez, Beverly Anne T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila (Philippines); Cosiñero, Hannah Shamina O.; Bacaoco, Miguel Y.; Ramos, Henry J. [Plasma Physics Laboratory, National Institute of Physics, College of Science, University of the Philippines Diliman, Quezon City 1101 (Philippines)

    2015-01-01

    Poly(tetrafluoroethylene) (PTFE) was irradiated by CF{sub 4} plasma produced in the gas discharge ion source facility to produce stable and robust superhydrophobic surfaces and to enhance the materials' oleophilic property for biological applications. The characterizations employed on the samples are contact angle measurements, analysis of the surface morphology (scanning electron microscopy), surface roughness measurements (atomic force microscopy) and analysis of the surface chemistry (Fourier transform infrared spectroscopy). Superhydrophobic behavior with water contact angles as high as 156° was observed. The wettability of all the treated samples was found to be stable in time as evidenced by the statistically insignificant differences in the hysteresis contact angles. The level of enhanced hydrophobicity depended on the plasma energies (i.e. irradiation times, discharge current, and discharge voltage); higher plasma energies produced surfaces with high hydrophobicity. The plasma treatment also enhanced the oleophilic property of the materials' surface as evidenced by the decrease in the PDMS-oil contact angle from 33° to as low as 10°. The superhydrophobicity of the modified PTFE and the enhancement of its oleophilic property were due to (1) the changes in the roughness of the surface, (2) the formation of nanoparticles or nanostructures on the surface, and (3) the changes in the surface chemistry. - Highlights: • PTFE surfaces were treated with direct CF{sub 4} using the gas discharge ion source. • Stable superhydrophobic behavior with water contact angles as high as 156° was recorded. • Surface roughness increased as the surface exhibited enhanced hydrophobicity. • Carbon nanoparticles were observed on the superhydrophobic PTFE surface. • Enhanced oleophilic property was observed with change in the PDMS-oil contact angle from 33° to 10°.

  19. Irradiation of poly(tetrafluoroethylene) surfaces by CF4 plasma to achieve robust superhydrophobic and enhanced oleophilic properties for biological applications

    International Nuclear Information System (INIS)

    Poly(tetrafluoroethylene) (PTFE) was irradiated by CF4 plasma produced in the gas discharge ion source facility to produce stable and robust superhydrophobic surfaces and to enhance the materials' oleophilic property for biological applications. The characterizations employed on the samples are contact angle measurements, analysis of the surface morphology (scanning electron microscopy), surface roughness measurements (atomic force microscopy) and analysis of the surface chemistry (Fourier transform infrared spectroscopy). Superhydrophobic behavior with water contact angles as high as 156° was observed. The wettability of all the treated samples was found to be stable in time as evidenced by the statistically insignificant differences in the hysteresis contact angles. The level of enhanced hydrophobicity depended on the plasma energies (i.e. irradiation times, discharge current, and discharge voltage); higher plasma energies produced surfaces with high hydrophobicity. The plasma treatment also enhanced the oleophilic property of the materials' surface as evidenced by the decrease in the PDMS-oil contact angle from 33° to as low as 10°. The superhydrophobicity of the modified PTFE and the enhancement of its oleophilic property were due to (1) the changes in the roughness of the surface, (2) the formation of nanoparticles or nanostructures on the surface, and (3) the changes in the surface chemistry. - Highlights: • PTFE surfaces were treated with direct CF4 using the gas discharge ion source. • Stable superhydrophobic behavior with water contact angles as high as 156° was recorded. • Surface roughness increased as the surface exhibited enhanced hydrophobicity. • Carbon nanoparticles were observed on the superhydrophobic PTFE surface. • Enhanced oleophilic property was observed with change in the PDMS-oil contact angle from 33° to 10°

  20. Improvement of surface properties induced by specific functionalization of polyethylene

    OpenAIRE

    Iguerb, Ourida

    2006-01-01

    In a first step, the surfaces of polyethylene films have been modified by grafting urethane monoacrylate monomer under UV irradiation in ambient air. For native films, this grafting was successfully realized but the grafted surface was heterogeneous. To overcome this drawback and obtain a smooth and homogeneous coating, a wet oxidation method using sodium hypochlorite through two different processes was developed. The oxidation mechanism of the PE films has been established. As a consequence ...

  1. Trends in the chemical properties in early transition metal carbide surfaces: A density functional study

    DEFF Research Database (Denmark)

    Kitchin, J.R.; Nørskov, Jens Kehlet; Barteau, M.A.;

    2005-01-01

    In this paper we present density functional theory (DFT) investigations of the physical, chemical and electronic structure properties of several close-packed surfaces of early transition metal carbides, including beta-Mo2C(0 0 0 1), and the (1 1 1) surfaces of TiC, VC, NbC, and TaC. The results are...... closest-packed pure metal surfaces, due to the tensile strain induced in the carbide surfaces upon incorporation of carbon into the lattice. Hydrogen atoms were found to adsorb more weakly on carbide surfaces than on the corresponding closest-packed pure metal surfaces only when there were surface carbon...

  2. Amino-terminated diamond surfaces: Photoelectron emission and photocatalytic properties

    Science.gov (United States)

    Zhu, Di; Bandy, Jason A.; Li, Shuo; Hamers, Robert J.

    2016-08-01

    We report a new approach to making stable negative electron-affinity diamond surfaces by terminating diamond with amino groups (also known as amine groups, -NH2). Previous studies have shown that negative electron affinity can be induced by terminating diamond surfaces with hydrogen, creating a surface dipole favorable toward electron emission. Here, we demonstrate that covalent tethering of positive charges in the form of protonated amino groups, -NH3+, also leads to negative electron affinity (NEA) and facile electron emission into vacuum and into water. Amino-terminated diamond was prepared using a very mild plasma discharge. Valence-band photoemission studies of the amino-terminated diamond samples show a characteristic "NEA" peak, demonstrating that the amino-terminated surface has NEA. Diamond's ability to emit electrons into water was evaluated using photochemical conversion of N2 to NH3. Time-resolved surface photovoltage studies were used to characterize charge separation at the diamond interface, and Mott-Schottky measurements were performed to characterize band-bending at the diamond-water interface. XPS studies show that the amino-terminated surfaces provide increased chemical resistance to oxidation compared with H-terminated diamond when illuminated with ultraviolet light.

  3. Crack-Growth Behavior of Laser Surface-Alloyed Low-Carbon Steel

    Science.gov (United States)

    Šturm, Roman; Žnidaršič, Matjaž; Grum, Janez

    2013-09-01

    Crack-growth behavior of Nd:YAG laser surface-alloyed as-received low-carbon steel Fe360B was evaluated. Thin surface layer was alloyed with silicon carbide SiC. During laser surface alloying process SiC powder dissolved in the melted pool. The surface-alloyed layer had as-solidified structure composed mainly of dendrites of ferrite, fine martensite needles, and retained austenite. The micro-hardness of the laser surface-alloyed layer was about 850 HV0.1. In laser surface-alloyed layer compressive residual stresses of average amount of σ RS = -100 MPa were obtained. In crack-growth tests comparison between specimens of as-received low-carbon steel Fe360B and the same steel with laser-alloyed surface was made. As the crack propagation was perpendicular to the interface between the laser-alloyed layers and the base metal, laser surface-alloyed specimens exhibited higher crack-growth resistance in the low stress intensity factor range Δ K th than as-received steel specimens.

  4. Behavior of Li on graphene surfaces observed using high-resolution ERDA

    Science.gov (United States)

    Nikko, Masataka; Nakajima, Kaoru; Hasegawa, Masataka; Kimura, Kenji

    2016-03-01

    Behavior of Li atoms deposited on the surfaces of highly oriented pyrolytic graphite (HOPG) and graphene-based thin films were observed at room temperature using high-resolution elastic recoil detection analysis (ERDA). On the HOPG surface, the deposited Li atoms intercalate into the bulk and no Li was observed in the surface region. The Li atoms were found to stay in the surface region (from the surface down to at least 3 nm) when the HOPG was irradiated with 200 keV He ions to a fluence of 5 × 1015 ions/cm2 before Li deposition. This indicates that stable Li sites are produced by the ion irradiation. It was also found that Li atoms are accumulated on the surface due to the oxidation by the residual gas. This oxidation occurs only on the surface and not inside HOPG. Graphene-based thin films were prepared on Cu by microwave plasma chemical vapor deposition. The Li atoms deposited on the graphene-based thin films are found to distribute through the film almost uniformly and no accumulation either on the surface or at the interface was observed.

  5. AeroCom INSITU Project: Comparison of Aerosol Optical Properties from In-situ Surface Measurements and Model Simulations

    Science.gov (United States)

    Schmeisser, L.; Andrews, E.; Schulz, M.; Fiebig, M.; Zhang, K.; Randles, C. A.; Myhre, G.; Chin, M.; Stier, P.; Takemura, T.; Krol, M. C.; Bian, H.; Skeie, R. B.; da Silva, A. M., Jr.; Kokkola, H.; Laakso, A.; Ghan, S.; Easter, R. C.

    2015-12-01

    AeroCom, an open international collaboration of scientists seeking to improve global aerosol models, recently initiated a project comparing model output to in-situ, surface-based measurements of aerosol optical properties. The model/measurement comparison project, called INSITU, aims to evaluate the performance of a suite of AeroCom aerosol models with site-specific observational data in order to inform iterative improvements to model aerosol modules. Surface in-situ data have the unique property of being traceable to physical standards, which is a big asset in accomplishing the overarching goal of bettering the accuracy of aerosol processes and predicative capability of global climate models. The INSITU project looks at how well models reproduce aerosol climatologies on a variety of time scales, aerosol characteristics and behaviors (e.g., aerosol persistence and the systematic relationships between aerosol optical properties), and aerosol trends. Though INSITU is a multi-year endeavor, preliminary phases of the analysis, using GOCART and other models participating in this AeroCom project, show substantial model biases in absorption and scattering coefficients compared to surface measurements, though the sign and magnitude of the bias varies with location and optical property. Spatial patterns in the biases highlight model weaknesses, e.g., the inability of models to properly simulate aerosol characteristics at sites with complex topography (see Figure 1). Additionally, differences in modeled and measured systematic variability of aerosol optical properties suggest that some models are not accurately capturing specific aerosol co-dependencies, for example, the tendency of in-situ surface single scattering albedo to decrease with decreasing aerosol extinction coefficient. This study elucidates specific problems with current aerosol models and suggests additional model runs and perturbations that could further evaluate the discrepancies between measured and modeled

  6. Microstructure and mechanical behavior of pulsed laser surface melted AISI D2 cold work tool steel

    Science.gov (United States)

    Yasavol, N.; Abdollah-zadeh, A.; Ganjali, M.; Alidokht, S. A.

    2013-01-01

    D2 cold work tool steel (CWTS) was subjected to pulse laser surface melting (PLSM) at constant frequency of 20 Hz Nd: YAG laser with different energies, scanning rate and pulse durations radiated to the surface. Characterizing the PLSM, with optical and field emission scanning electron microscopy, electron backscattered diffraction and surface hardness mapping technique was used to evaluate the microhardness and mechanical behavior of different regions of melting pool. Increasing laser energy and reducing the laser scanning rate results in deeper melt pool formation. Moreover, PLSM has led to entirely dissolution of the carbides and re-solidification of cellular/dendritic structure of a fine scale surrounded by a continuous interdendritic network. This caused an increase in surface microhardness, 2-4 times over that of the base metal.

  7. Experimental and numerical study on free surface behavior of windowless target

    International Nuclear Information System (INIS)

    The formation and control method of coolant free surface is one of the key technologies for the design of windowless target in accelerator driven sub-critical system (ADS). Experimental and CFD investigations on free surface behavior were performed in a scaled windowless target model by using water as test fluid. Laser induced fluorescence was applied for flow field visualization. The free surface and flow field visualization were obtained at Re=30000-50000. Under high Re conditions, an unsteady vortex pair was obtained. By decreasing Re, the structure of the vortex becomes more turbulent. CFD simulation was performed using LES and kω-SST turbulence models, separately. The numerical results show that LES model can qualitatively reproduce the characteristics of flow field and free surface. (authors)

  8. Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.; Ghosn, Louis J.; Kalluri, Sreeramesh

    2004-01-01

    The development of advanced high performance constant-volume-combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz) in conjunction with the mechanical fatigue loads (10 Hz). The mechanical high cycle fatigue (HCF) testing of some laser pre-exposed specimens has also been conducted under a frequency of 100 Hz to determine the laser surface damage effect. The test results have indicated that material surface oxidation and creep-enhanced fatigue is an important mechanism for the surface crack initiation and propagation under the simulated CVCCE engine conditions.

  9. Biofouling behavior and performance of forward osmosis membranes with bioinspired surface modification in osmotic membrane bioreactor.

    Science.gov (United States)

    Li, Fang; Cheng, Qianxun; Tian, Qing; Yang, Bo; Chen, Qianyuan

    2016-07-01

    Forward osmosis (FO) has received considerable interest for water and energy related applications in recent years. Biofouling behavior and performance of cellulose triacetate (CTA) forward osmosis membranes with bioinspired surface modification via polydopamine (PD) coating and poly (ethylene glycol) (PEG) grafting (PD-g-PEG) in a submerged osmotic membrane bioreactor (OMBR) were investigated in this work. The modified membranes exhibited lower flux decline than the pristine one in OMBR, confirming that the bioinspired surface modification improved the antifouling ability of the CTA FO membrane. The result showed that the decline of membrane flux related to the increase of the salinity and MLSS concentration of the mixed liquid. It was concluded that the antifouling ability of modified membranes ascribed to the change of surface morphology in addition to the improvement of membrane hydrophilicity. The bioinspired surface modifications might improve the anti-adhesion for the biopolymers and biocake. PMID:27089532

  10. Systematic Surface Phase Transition of Ag Thin Films by Iodine Functionalization at Room Temperature: Evolution of Optoelectronic and Texture Properties.

    Science.gov (United States)

    Bashouti, Muhammad Y; Talebi, Razieh; Kassar, Thaer; Nahal, Arashmid; Ristein, Jürgen; Unruh, Tobias; Christiansen, Silke H

    2016-01-01

    We show a simple room temperature surface functionalization approach using iodine vapour to control a surface phase transition from cubic silver (Ag) of thin films into wurtzite silver-iodid (β-AgI) films. A combination of surface characterization techniques (optical, electronical and structural characterization) reveal distinct physical properties of the new surface phase. We discuss the AgI thin film formation dynamics and related transformation of physical properties by determining the work-function, dielectric constant and pyroelectric behavior together with morphological and structural thin film properties such as layer thickness, grain structure and texture formation. Notable results are: (i) a remarkable increase of the work-function (by 0.9 eV) of the Ag thin layer after short a iodine exposure time (≤60 s), with simultaneous increase of the thin film transparency (by two orders of magnitude), (ii) pinning of the Fermi level at the valance band maximum upon iodine functionalization, (iii) 84% of all crystallites grain were aligned as a result of the evolution of an internal electric field. Realizing a nano-scale layer stack composed of a dielectric AgI layer on top of a metallic thin Ag layer with such a simple method has some technological implications e.g. to realize optical elements such as planar optical waveguides. PMID:26899434

  11. Wetting properties of liquid lithium on select fusion relevant surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Fiflis, P., E-mail: Fiflis1@illinois.edu; Press, A.; Xu, W.; Andruczyk, D.; Curreli, D.; Ruzic, D.N.

    2014-12-15

    Highlights: • Liquid lithium wets W, Mo, 316 SS, Ta, and TZM at sufficiently high temperatures. • Wetting temperatures between 284 °C (TZM) and 353 °C (Ta) for untreated materials. • Argon GDC and lithium evaporation treatments reduce wetting temperature. - Abstract: Research into lithium as a plasma facing component material has illustrated its ability to engender low recycling operation at the plasma edge leading to higher energy confinement times. Introducing lithium into a practical fusion device would almost certainly require the lithium to be flowing to maintain a clean lithium surface for gettering. Several conceptual designs have been proposed, like the LiMIT concept of UIUC (Ruzic, 2011). Critical to the implementation of these devices is understanding the interactions of liquid lithium with various surfaces. For a device that relies on thermoelectric magnetohydrodynamic drive, such as the LiMIT concept, two of the critical interactions are the wetting of materials by lithium, which may be characterized by the contact angle between the lithium and the surface, and the relative thermopower between lithium and potential substrate materials. Experiments have been performed into the contact angle of liquid lithium droplets with various surfaces, as well as methods to decrease the contact angle of lithium with a given surface. The contact angle, as well as its dependence on temperature was measured. For example, at 200 °C, tungsten registers a contact angle of 130°, whereas above its wetting temperature of 350 °C, the contact angle is less than 80°. Glow discharge cleaning of the target surface as well as evaporation of a thin layer of liquid lithium onto the surface prior to performing wetting measurements were both found to decrease the wetting temperature.

  12. Wetting properties of liquid lithium on select fusion relevant surfaces

    International Nuclear Information System (INIS)

    Highlights: • Liquid lithium wets W, Mo, 316 SS, Ta, and TZM at sufficiently high temperatures. • Wetting temperatures between 284 °C (TZM) and 353 °C (Ta) for untreated materials. • Argon GDC and lithium evaporation treatments reduce wetting temperature. - Abstract: Research into lithium as a plasma facing component material has illustrated its ability to engender low recycling operation at the plasma edge leading to higher energy confinement times. Introducing lithium into a practical fusion device would almost certainly require the lithium to be flowing to maintain a clean lithium surface for gettering. Several conceptual designs have been proposed, like the LiMIT concept of UIUC (Ruzic, 2011). Critical to the implementation of these devices is understanding the interactions of liquid lithium with various surfaces. For a device that relies on thermoelectric magnetohydrodynamic drive, such as the LiMIT concept, two of the critical interactions are the wetting of materials by lithium, which may be characterized by the contact angle between the lithium and the surface, and the relative thermopower between lithium and potential substrate materials. Experiments have been performed into the contact angle of liquid lithium droplets with various surfaces, as well as methods to decrease the contact angle of lithium with a given surface. The contact angle, as well as its dependence on temperature was measured. For example, at 200 °C, tungsten registers a contact angle of 130°, whereas above its wetting temperature of 350 °C, the contact angle is less than 80°. Glow discharge cleaning of the target surface as well as evaporation of a thin layer of liquid lithium onto the surface prior to performing wetting measurements were both found to decrease the wetting temperature

  13. The effects of steam on the surface properties of palygorskite: Implications for palygorskite-water interactions

    Science.gov (United States)

    Kadakia, Abhy

    Early studies on the effects of steam on montmorillonite reported a loss of osmotic swelling capacity and gelling ability of montmorillonite (Bish et al., 1997; Couture, 1985; Oscarson and Dixon, 1989; Zhu, 2009). However, the crystal structure, cation-exchange capacity, and hydration/dehydration behavior of montmorillonite were preserved. Similar steaming experiments were conducted in the current studies on palygorskite (PFl-1) at 225°C for six days in Teflon-lined Parr vessels. All untreated and steam-treated materials were examined by X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), ζ-potential, and rheological measurements. XRD and TGA data show that the crystal structure, mineralogy, and dehydration behavior of steamed palygorskites were unchanged after steam treatment. XPS revealed no changes in binding-energy peak positions of the surface Si, Mg, and O ions (XPS provides no information on the chemical state of H atoms). Rheological measurements showed that suspensions of steam-treated palygorskite in deionized H2O (5% w/w) are unstable, and the suspensions are Newtonian in nature. The flow curves also revealed a significant reduction in yield stresses after steam treatment, indicating collapse of the clay particle network in water. The ζ-potential decreased after steam treatment, with untreated palygorskite having a value of -26.1 mV and steam-treated material having a value of -18.3 mV. The reduction of surface charge may be sufficient to reduce the electrostatic repulsion between the clay particles, thereby allowing van der Waal attractive forces to dominate. Hence, steam-treated palygorskite flocculates and settles quickly in water. The decreased ζ-potentials are likely associated with decreased Lewis basicity, which can render the clay particles less hydrophilic or even moderately hydrophobic. Both N 2 (BET) and ethylene glycol monoethyl ether (EGME) adsorption surface areas of palygorskite

  14. Magnetic Behavior of Single La$_{0.67}$Ca$_{0.33}$MnO$_3$ Nanotubes: Surface and Shape Effects

    OpenAIRE

    Dolz, M.; Bast, W.; Antonio, D.; Pastoriza, H.; Curiale, J.; Sanchez, R. D.; Leyva, A. G.

    2007-01-01

    We report magnetization experiments in two magnetically isolated ferromagnetic nanotubes of perovskite La$_{0.67}$Ca$_{0.33}$MnO$_3$. The results show that the magnetic anisotropy is determined by the sample shape although the coercive field is reduced by incoherent magnetization reversal modes. The temperature dependence of the magnetization reveals that the magnetic behavior is dominated by grain surface properties. These measurements were acquired using a Silicon micro-mechanical oscillato...

  15. Tribological Behavior of Gampsocleis Gratiosa Foot Pad Against Vertical Flat Surfaces

    Institute of Scientific and Technical Information of China (English)

    Chen Dong-hui; Tong Jin; Sun Ji-yu; Ren Lu-quan

    2005-01-01

    Some tribological behavior between mature Gampsocleis gratiosa foot pads and vertical flats of different materials were studied in this work. stereomieroscope (SMS) and scanning electron microscope (SEM) were used to measure the morphology of the Gampsocleis gratiosa foot pads. An atomic force microscope (AFM) was used to measure the morphologies of the surfaces of glass and a wall doped with calcium carbonate material. The attaching behavior of Gampsocleis gratiosa feet on the two vertical surfaces was observed. The attaching force (perpendicular to the vertical surface) and the static frictional force (along the direction of gravitation) of Gampsocleis gratiosa foot pads on a vertical glass were measured. It was shown that the average attaching force is 50.59 mN and the static frictional force is 259.10 mN. The physical models of the attaching interface between Gampsocleis gratiosa foot pads and the two vertical surfaces were proposed. It was observed that the foot pads are smooth in macroscale; however, the pad surface is composed by approximate hexagonal units with sizes of 3 μm to 7 μm in microscale; the adjacent units are separated by nanoscale grooves. The Observations showed that the Gampsocleis gratiosa can not climb the vertical calcium carbonate wall; in contrast, they can easily climb the vertical glass surface. Based on the features of the geometrical morphologies of the foot pads and the glass surface, we speculate that the attaching force and strong static frictional force are attributed to the interinlays between the deformable Gampsocleis gratiosa foot pads and the nanoscale sharp tips of the glass surface.

  16. Physical vapor deposited titanium thin films for biomedical applications: Reproducibility of nanoscale surface roughness and microbial adhesion properties

    Energy Technology Data Exchange (ETDEWEB)

    Lüdecke, Claudia [Chair of Materials Science (CMS), Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, D-07743, Jena (Germany); Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Bio Pilot Plant, Beutenbergstraße 11a, D-07745, Jena (Germany); Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Jena (Germany); Bossert, Jörg [Chair of Materials Science (CMS), Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, D-07743, Jena (Germany); Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Jena (Germany); Roth, Martin [Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Bio Pilot Plant, Beutenbergstraße 11a, D-07745, Jena (Germany); Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Jena (Germany); Jandt, Klaus D., E-mail: k.jandt@uni-jena.de [Chair of Materials Science (CMS), Faculty of Physics and Astronomy, Friedrich Schiller University Jena, Löbdergraben 32, D-07743, Jena (Germany); Jena Center for Soft Mater, Friedrich Schiller University Jena, Jena (Germany); Jena School for Microbial Communication (JSMC), Friedrich Schiller University Jena, Jena (Germany)

    2013-09-01

    The surface topography is of great importance for the biological performance of titanium based implants since it may influence the initial adsorption of proteins, cell response, as well as microbial adhesion. A recently described technique for the preparation of titanium thin films with an adjustable surface roughness on the nanometer scale is the physical vapor deposition (PVD). The aims of this study were to statistically evaluate the reproducibility of nanorough titanium thin films prepared by PVD using an atomic force microscopy (AFM) based approach, to test the microbial adhesion in dependence of the nanoscale surface roughness and to critically discuss the parameters used for the characterization of the titanium surfaces with respect to AFM microscope settings. No statistically significant differences were found between the surface nanoroughnesses of the PVD prepared titanium thin films. With increasing surface nanoroughness, the coverage by Escherichia coli decreased and the microbial cells were increasingly patchy distributed. The calculated roughness values significantly increased with increasing AFM scan size, while image resolution and pixel density had no influence on this effect. Our study shows that PVD is a suitable tool to reproducibly prepare titanium thin films with a well-defined surface topography on the nanometer scale. These surfaces are, thus, a suitable 2D model system for studies addressing the interaction between surface nanoroughness and the biological system. First results show that surface roughness even on the very low nanometer scale has an influence on bacterial adhesion behavior. These findings give new momentum to biomaterials research and will support the development of biomaterials surfaces with anti-infectious surface properties.

  17. Investigations of surface structural, dynamical, and magnetic properties of systems exhibiting multiferroicity, and topological phases by helium scattering spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    El-Batanouny, Maged

    2015-08-03

    We propose to investigate the surface structural, dynamics and magnetic properties of the novel class of topological insulator crystals, as well as crystals that exhibit multiferroicity, magnetoelectricity and thermoelectricity. Topological insulators (TIs) are a new class of insulators in which a bulk gap for electronic excitations is generated because of the strong spin-orbit coupling inherent to these systems. These materials are distinguished from ordinary insulators by the presence of gapless metallic surface states, resembling chiral edge modes in quantum Hall systems, but with unconventional spin textures. These exotic metallic states are formed by topological conditions that also render the electrons travelling on such surfaces insensitive to scattering by impurities. The electronic quasi-particles populating the topological surface state are Dirac fermions; they have a linear dispersion and thus are massless just like photons. We propose to investigate the interaction of these massless Dirac fermions with the massive lattice in the newly discovered crystals, Bi2Se3, Bi2Te3 and Sb2Te3. We shall use inelastic helium beam scattering from surfaces to search for related signatures in surface phonon dispersions mappings that cover the entire surface Brillouin zone of these materials. Our recent investigations of the (001) surface of the multiferroic crystals (Li/Na)Cu2O2 revealed an anomalous surface structural behavior where surface Cu$^{2+}$ row rise above the surface plane as the crystal was cooled. Subsequent worming revealed the onset of a thermally activated incommensurate surface phase, driven by the elevated rows. We are currently investigating the structure of the magnetic phases in these quasi-one-dimensional magnetic rows. Multiferroics are excellent candidates for large magnetoelectric response. We propose to extend this investigation to the class of delafossites which are also multiferroics and have been investigated as good candidates for

  18. Generic strong coupling behavior of Cooper pairs in the surface of superfluid nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Pillet, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France); Sandulescu, N. [DPTA/Service de Physique nucleaire, CEA/DAM Ile de France, BP12, F-91680 Bruyeres-le-Chatel (France)]|[Institute of Physics and Nuclear Engineering, 76900 Bucharest (Romania)]|[Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France); Schuck, P. [Institut de Physique Nucleaire, CNRS, UMR 8608, Orsay, F-91406 (France)]|[Universite Paris-Sud, Orsay, F-91505 (France)

    2007-01-15

    With realistic HFB calculations, using the D1S Gogny force, we reveal a generic behavior of concentration of small sized Cooper pairs (2-3 fm) in the surface of superfluid nuclei. This study confirms and extends previous results given in the literature that use more schematic approaches. It is shown that the strong concentration of pair probability of small Cooper pairs in the nuclear surface is a quite general and generic feature and that nuclear pairing is much closer to the strong coupling regime than previously assumed.

  19. Surface characteristics and electrochemical corrosion behavior of NiTi alloy coated with IrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, M.; Wang, Y.B.; Zhang, X.; Li, Q.H.; Liu, Q. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Cheng, Y., E-mail: chengyan@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Biomedical engineering research center, Shenzhen institution of Peking University, Shenzhen 518057 (China); Zheng, Y.F. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Biomedical engineering research center, Shenzhen institution of Peking University, Shenzhen 518057 (China); Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871 (China); Xi, T.F. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Biomedical engineering research center, Shenzhen institution of Peking University, Shenzhen 518057 (China); Wei, S.C. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Biomedical engineering research center, Shenzhen institution of Peking University, Shenzhen 518057 (China); Department of Oral and Maxillofacial Surgery, School and Hospital of Stomatology, Peking University, Beijing 100871 (China)

    2013-01-01

    The aim of this work is to investigate the surface characteristics and corrosion behavior of NiTi (50.6 at.% Ni) shape memory alloy coated by a ceramic-like and highly biocompatible material, iridium oxide (IrO{sub 2}). IrO{sub 2} coatings were prepared by thermal decomposition of H{sub 2}IrCl{sub 6} {center_dot} 6H{sub 2}O precursor solution at the temperature of 300 Degree-Sign C, 400 Degree-Sign C and 500 Degree-Sign C, respectively. The surface morphology and microstructure of the coatings were investigated by scanning electron microscope (SEM) and glancing angle X-ray diffraction (GAXRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the surface elemental composition. Corrosion resistance property of the coated samples was studied in a simulated body fluid at 37 {+-} 1 Degree-Sign C by electrochemical method. It was found that the morphology and microstructure of the coatings were closely related to the oxidizing temperatures. A relatively smooth, intact and amorphous coating was obtained when the H{sub 2}IrCl{sub 6}{center_dot}6H{sub 2}O precursor solution (0.03 mol/L) was thermally decomposed at 300 Degree-Sign C for 0.5 h. Compared with the bare NiTi alloy, IrO{sub 2} coated samples exhibited better corrosion resistance behavior to some extent. - Highlights: Black-Right-Pointing-Pointer First report on the surface coating of NiTi alloy by iridium oxide (IrO{sub 2}). Black-Right-Pointing-Pointer The coatings' microstructure was closely related to the oxidizing temperatures. Black-Right-Pointing-Pointer The corrosion resistance of NiTi alloy was improved by IrO{sub 2} coatings.

  20. Surface characteristics and electrochemical corrosion behavior of NiTi alloy coated with IrO2

    International Nuclear Information System (INIS)

    The aim of this work is to investigate the surface characteristics and corrosion behavior of NiTi (50.6 at.% Ni) shape memory alloy coated by a ceramic-like and highly biocompatible material, iridium oxide (IrO2). IrO2 coatings were prepared by thermal decomposition of H2IrCl6 · 6H2O precursor solution at the temperature of 300 °C, 400 °C and 500 °C, respectively. The surface morphology and microstructure of the coatings were investigated by scanning electron microscope (SEM) and glancing angle X-ray diffraction (GAXRD). X-ray photoelectron spectroscopy (XPS) was employed to determine the surface elemental composition. Corrosion resistance property of the coated samples was studied in a simulated body fluid at 37 ± 1 °C by electrochemical method. It was found that the morphology and microstructure of the coatings were closely related to the oxidizing temperatures. A relatively smooth, intact and amorphous coating was obtained when the H2IrCl6·6H2O precursor solution (0.03 mol/L) was thermally decomposed at 300 °C for 0.5 h. Compared with the bare NiTi alloy, IrO2 coated samples exhibited better corrosion resistance behavior to some extent. - Highlights: ► First report on the surface coating of NiTi alloy by iridium oxide (IrO2). ► The coatings’ microstructure was closely related to the oxidizing temperatures. ► The corrosion resistance of NiTi alloy was improved by IrO2 coatings.

  1. Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Xiaoliang; Wang Xiu; Kong Wen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Graduate University of Chinese Academy of Sciences, Beijing 100049 (China); Yi Gewen [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Jia Junhong, E-mail: jhjia@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2011-10-15

    In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

  2. Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

    Science.gov (United States)

    Zhang, Xiaoliang; Wang, Xiu; Kong, Wen; Yi, Gewen; Jia, Junhong

    2011-10-01

    In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

  3. Indication of insensitivity of planetary weathering behavior and habitable zone to surface land fraction

    CERN Document Server

    Abbot, Dorian S; Ciesla, Fred J

    2012-01-01

    It is likely that unambiguous habitable zone terrestrial planets of unknown water content will soon be discovered. Water content helps determine surface land fraction, which influences planetary weathering behavior. This is important because the silicate weathering feedback determines the width of the habitable zone in space and time. Here a low-order model of weathering and climate, useful for gaining qualitative understanding, is developed to examine climate evolution for planets of various land-ocean fractions. It is pointed out that, if seafloor weathering does not depend directly on surface temperature, there can be no weathering-climate feedback on a waterworld. This would dramatically narrow the habitable zone of a waterworld. Results from our model indicate that weathering behavior does not depend strongly on land fraction for partially ocean-covered planets. This is powerful because it suggests that previous habitable zone theory is robust to changes in land fraction, as long as there is some land. F...

  4. Preparation, anti-biofouling and drag-reduction properties of a biomimetic shark skin surface

    Directory of Open Access Journals (Sweden)

    Xia Pu

    2016-04-01

    Full Text Available Shark skin surfaces show non-smoothness characteristics due to the presence of a riblet structure. In this study, biomimetic shark skin was prepared by using the polydimethylsiloxane (PDMS-embedded elastomeric stamping (PEES method. Scanning electron microscopy (SEM was used to examine the surface microstructure and fine structure of shark skin and biomimetic shark skin. To analyse the hydrophobic mechanism of the shark skin surface microstructure, the effect of biomimetic shark skin surface microstructure on surface wettability was evaluated by recording water contact angle. Additionally, protein adhesion experiments and anti-algae adhesion performance testing experiments were used to investigate and evaluate the anti-biofouling properties of the surface microstructure of biomimetic shark skin. The recorded values of the water contact angle of differently microstructured surfaces revealed that specific microstructures have certain effects on surface wettability. The anti-biofouling properties of the biomimetic shark skin surface with microstructures were superior to a smooth surface using the same polymers as substrates. Moreover, the air layer fixed on the surface of the biomimetic shark skin was found to play a key role in their antibiont adhesion property. An experiment into drag reduction was also conducted. Based on the experimental results, the microstructured surface of the prepared biomimetic shark skin played a significant role in reducing drag. The maximum of drag reduction rate is 12.5%, which is higher than the corresponding maximum drag reduction rate of membrane material with a smooth surface.

  5. High-temperature metal alloy radiant property measurements in conjunction with advanced surface spectroscopy

    International Nuclear Information System (INIS)

    The purpose of this work is to study the radiative and optical properties of pure liquid metal surfaces using both a state-of-the-art radiation property measurement system and the recently developed techniques of surface analysis. These techniques allow detailed analysis of the atomic composition of a metal surface. Research reported to date has not utilized these tools, so sample materials have been impure and of unknown surface composition. An apparatus was fabricated which will allow complete radiative property measurements and surface spectroscopy to be done in the same device. This system employs argon ion sputtering, Auger electron spectroscopy (AES), and ultra high vacuum techniques and makes radiative property measurements as a function of angle, wavelength, and temperature. After assembly and shakedown, the apparatus was used to make two sets of measurements. The data are being analyzed. Theoretical work to compare our data to predictions derived from the Fresnel equations and free electron theory has been initiated

  6. Dielectric Properties of Vesta's Surface as Constrained by Dawn VIR Observations

    CERN Document Server

    Palmer, Elizabeth M; Capria, Maria Teresa; Tosi, Federico

    2015-01-01

    Earth and orbital based radar observations of asteroids provide a unique opportunity to characterize surface roughness and the dielectric properties of their surfaces, as well as potentially explore some of their shallow subsurface physical properties. If the dielectric and topographic properties of asteroid's surfaces are defined, we can constrain their textural characteristics as well as potential subsurface volatile enrichment using the observed radar backscatter. To achieve this objective, we establish the first dielectric model of asteroid Vesta for the case of a dry, volatile-poor regolith -- employing an analogy to the dielectric properties of lunar regolith, and adjusted for the surface densities and temperatures deduced from Dawn's Visible and InfraRed mapping spectrometer (VIR). Our model suggests that the dielectric constant at the surface of Vesta is relatively constant, ranging from 2.0 to 2.1 from the night- to day-side of Vesta, while the loss tangent shows slight variation as a function of diu...

  7. Qualitative behavior of solutions for thermodynamically consistent Stefan problems with surface tension

    OpenAIRE

    Pruess, Jan; Simonett, Gieri; Zacher, Rico

    2011-01-01

    The qualitative behavior of a thermodynamically consistent two-phase Stefan problem with surface tension and with or without kinetic undercooling is studied. It is shown that these problems generate local semiflows in well-defined state manifolds. If a solution does not exhibit singularities in a sense made precise below, it is proved that it exists globally in time and its orbit is relatively compact. In addition, stability and instability of equilibria is studied. In particular, it is shown...

  8. Nanocrystal and surface alloy properties of bimetallic Gold-Platinum nanoparticles

    Directory of Open Access Journals (Sweden)

    Mott Derrick

    2006-01-01

    Full Text Available AbstractWe report on the correlation between the nanocrystal and surface alloy properties with the bimetallic composition of gold-platinum(AuPt nanoparticles. The fundamental understanding of whether the AuPt nanocrystal core is alloyed or phase-segregated and how the surface binding properties are correlated with the nanoscale bimetallic properties is important not only for the exploitation of catalytic activity of the nanoscale bimetallic catalysts, but also to the general exploration of the surface or interfacial reactivities of bimetallic or multimetallic nanoparticles. The AuPt nanoparticles are shown to exhibit not only single-phase alloy character in the nanocrystal, but also bimetallic alloy property on the surface. The nanocrystal and surface alloy properties are directly correlated with the bimetallic composition. The FTIR probing of CO adsorption on the bimetallic nanoparticles supported on silica reveals that the surface binding sites are dependent on the bimetallic composition. The analysis of this dependence further led to the conclusion that the relative Au-atop and Pt-atop sites for the linear CO adsorption on the nanoparticle surface are not only correlated with the bimetallic composition, but also with the electronic effect as a result of the d-band shift of Pt in the bimetallic nanocrystals, which is the first demonstration of the nanoscale core-surface property correlation for the bimetallic nanoparticles over a wide range of bimetallic composition.

  9. Properties of surface arc discharge in a supersonic airflow

    International Nuclear Information System (INIS)

    An experimental study of a direct-current, surface arc discharge in a Mach 2 cold supersonic airflow is presented. The surface arc discharge is generated with cylindrical tungsten electrodes flush-mounted on a boron-nitride ceramic plate embedded in the lower wall of the supersonic test section. In the presence of airflow, gas breakdown voltage increases from 1.5 kV in stationary air to 2 kV due to particle number density augmentation in the flow. The surface arc discharge transforms from a continuous mode in stationary air to a pulsed-repetitive mode in the flow. The mean time interval between discharge pulses is about 4.3 ms. For a single pulse, arc discharge occupies only about 60 μs. The discharge photos taken by a high-speed CCD camera (framing rate 1125 Hz) validate this pulsed-repetitive process and indicate that the plasma channel of the surface arc discharge is blown downstream by the supersonic flow. As the length of the plasma channel increases, the discharge voltage also increases. When the channel length reaches a critical value (∼25 mm), the dc power supply (3 kV-4 kW) cannot sustain the discharge voltage (∼3 kV) and the Joule heating energy cannot balance the dissipation of constrained convection, and hence the discharge quenches immediately. Current and voltage measurements demonstrate that the discharge process in a single pulse can be separated into three distinct phases: strong-pulsed breakdown process, steady discharge process and discharge attenuation process. Finally, the underlying mechanism of the dynamic process of surface arc discharge in supersonic flow is discussed. This paper provides more insights into the mechanism of supersonic flow control (in particular, shock waves) by a surface arc discharge.

  10. Influence of bilirubin on surface tension properties of lung surfactant.

    OpenAIRE

    Amato, M; Schürch, S; Grunder, R; Bachofen, H.; Burri, P H

    1996-01-01

    AIM: To investigate the influence of bilirubin on the surface tension activity of a porcine derived (Curosurf) and synthetic (Exosurf) surfactant. METHODS: The captive bubble surfactometer at phospholipid doses of 0.5 mg/ml (low dose) and 1 mg/ml (high dose) in solutions of increasing bilirubin concentrations (0.25, 0.5, and 1.0 mg/ml) was used. RESULTS: Curosurf (without bilirubin) showed a higher surface f1p4ion activity than Exosurf, as shown by area compression of 30 (SD 0.6)% compared wi...

  11. Control of the morphology and surface properties of nickel ferrite

    International Nuclear Information System (INIS)

    Nickel ferrite powders with particle sizes in the 3-5 μm range have been prepared from coprecipitated nickel-iron oxalate precursors. Firing the nickel-iron oxalate precursor in the range 300-1100oC produced samples of high chemical purity, while introducing significant variations in the distribution of crystallite sizes and surface morphologies. An increase in the powder density from 4.2 to 5.2 g cm-3 and a decrease in the surface area of the nickel ferrite from 120 to 0.2 m2 g-1 were effected by increasing the firing temperature to 1100oC. (author)

  12. Synthesis of Branch Fluorinated Cationic Surfactant and Surface Properties

    Directory of Open Access Journals (Sweden)

    Hongke Wu

    2014-01-01

    Full Text Available A novel fluorinated quaternary ammonium salt cationic surfactant N,N,N-trimethyl-2-[[4-[[3,4,4,4-tetrafluoro-2-[1,2,2,2-tetrafluoro-1-(trifluoromethylethyl]-1,3-bis(tri-fluoromethyl-1-buten-1-yl]oxy]-benzoyl]amino]-iodide (FQAS was synthesized successfully, and its structure was characterized by FTIR, 1H-NMR, 19F-NMR, and MS. The surface activities of FQAS and the effect of temperature, electrolyte, and combination with hydrocarbon surfactant were investigated. The results showed that FQAS exhibited excellent surface activity and combination with hydrocarbon surfactant.

  13. Surface properties of hard protective coatings studied by optical techniques

    Science.gov (United States)

    Jaglarz, Janusz; Wolska, N.; Mitura, K.; Duraj, R.; Marszalek, K. W.; El Kouari, Y.

    2016-06-01

    The paper describes optical study of SiC, C and NiC layers deposited on Si substrates by double beam ion sputtering (DBIS) method. The following optical methods: ellipsometry, bidirectional reflection distribution function (BRDF) and total integrated scattering (TIS) studies have been applied. The obtained results allowed us to determine the refractive indices, extinction coefficients and the roughness parameters of DBIS films. Also surface profiles of optical constants determined from scanning ellipsometric measurements have been presented. The power spectral density functions (PSD) of surface roughness for studied samples have been determined. The influence of the deposition technology on film topography has been discussed.

  14. Properties of distance functions on convex surfaces and Alexandrov spaces

    CERN Document Server

    Rataj, Jan

    2009-01-01

    If $X$ is a convex surface in a Euclidean space, then the squared (intrinsic) distance function $\\dist^2(x,y)$ is d.c. (DC, delta-convex) on $X\\times X$ in the only natural extrinsic sense. For the proof we use semiconcavity (in an intrinsic sense) of $\\dist^2(x,y)$ on $X \\times X$ if $X$ is an Alexandrov space with nonnegative curvature. Applications concerning $r$-boundaries (distance spheres) and the ambiguous locus (exoskeleton) of a closed subset of a convex surface are given.

  15. Characterization of the whistles of Tursiops truncatus (Cetacea: Delphinidae and their association with surface behavior

    Directory of Open Access Journals (Sweden)

    Romero-Mujalli, Daniel

    2014-04-01

    Full Text Available Acoustic communication is common in dolphins and encompasses a variety of sounds, either vocal or not. Among vocalizations, whistles are continuous narrow-band and frequency-modulated sounds, with a frequency range between 2-24 kHz. The aim of this study was to characterize the whistles of a resident group of bottlenose dolphins Tursiops truncatus in the coast of Aragua state (Venezuela and to determine their association with surface behavior. On average, whistle frequency ranged from 7 to 16 kHz. Six types of whistles, according to the contour of frequency modulation, were found: constant, ascending, descending, ascending-descending, descending-ascending and multiple. Only two behavioral states were observed: traveling and socialization. There was significant association between the type of whistle and behavior: whistles of medium complexity (ascending-descending were preferred during traveling and significantly avoided during socialization. Furthermore, whistles emitted during socialization were longer, of broader bandwidth, and spanning over lower frequencies than those emitted during traveling. The variation of whistles according to surface behavior confirms that they have a communicational value. Future research should focus on the causes and consequences of whistle emission to elucidate their referential function.

  16. Mechanical properties of titanium alloys with strengthened surface layers

    Directory of Open Access Journals (Sweden)

    I.M. Pohreliuk

    2011-12-01

    Full Text Available Influence of oxinitriding and boriding on the mechanical properties (ultimate strength to destruction at uniaxial tension, plasticity, tendency to delayed destruction, fatigue resistance at bending with rotation, fatigue life at lowcycle pure bending of titanium alloys is studied.

  17. The effect of surface treatment on the interfacial properties in carbon fibre/epoxy matrix composites

    OpenAIRE

    Bogoeva-Gaceva, Gordana; Janevski, Aco; Dekanski, Aleksandar; D. BUREVSKI

    1995-01-01

    Carbon fibres with different degrees of surface oxidation, as well as epoxy-sized fibres, were used to prepare epoxy composites in order to compare the effects of the fibres surface chemistry on the interfacial properties. X-ray photoelectron spectroscopy, water vapour adsorption measurements and contact angle examination were applied to characterize the carbon fibre surfaces. A correlation was found between the content of primary adsorption sites on the fibre surface and interlaminar shear s...

  18. Effect of cleaning and sterilization on titanium implant surface properties and cellular response

    OpenAIRE

    Park, Jung Hwa; Olivares-Navarrete, Rene; Baier, Robert E.; Meyer, Anne E.; Tannenbaum, Rina; Boyan, Barbara D.; Schwartz, Zvi

    2011-01-01

    Titanium (Ti) has been widely used as an implant material due to the excellent biocompatibility and corrosion resistance of its oxide surface. Biomaterials must be sterile before implantation, but the effects of sterilization on their surface properties have been less well studied. The effects of cleaning and sterilization on surface characteristics were bio-determined using contaminated and pure Ti substrata first manufactured to present two different surface structures: pretreated titanium ...

  19. Effect of cumulative helium bombardments on the surface and structural properties of tungsten

    International Nuclear Information System (INIS)

    The surface and structural properties of tungsten after cumulative helium bombardments have been investigated using molecular dynamics simulations. Helium atoms at 80 eV were injected into tungsten (0 0 1), (1 1 0) and (1 1 1) surfaces. The retention and distribution of helium atoms, the formation and growth of helium clusters and the surface evolution of tungsten substrates are found to be influenced by surface orientations and temperatures

  20. Electronic and Chemical Properties of a Surface-Terminated Screw Dislocation in MgO

    Energy Technology Data Exchange (ETDEWEB)

    Mckenna, Keith P.

    2013-12-18

    Dislocations represent an important and ubiquitous class of topological defect found at the surfaces of metal oxide materials. They are thought to influence processes as diverse as crystal growth, corrosion, charge trapping, luminescence, molecular adsorption and catalytic activity, however, their electronic and chemical properties remain poorly understood. Here, through a detailed first principles investigation into the properties of a surface terminated screw dislocation in MgO we provide atomistic insight into these issues. We show that surface dislocations can exhibit intriguing electron trapping properties which are important for understanding the chemical and electronic characteristics of oxide surfaces. The results presented in this article taken together with recent experimental reports show that surface dislocations can be equally as important as more commonly considered surface defects, such as steps, kinks and vacanies, but are now just beginning to be understood.

  1. Ionic Behavior in Highly Concentrated Aqueous Solutions Nanoconfined between Discretely Charged Silicon Surfaces.

    Science.gov (United States)

    Qiu, Yinghua; Ma, Jian; Chen, Yunfei

    2016-05-17

    Through molecular dynamics simulations considering thermal vibration of surface atoms, ionic behaviors in concentrated NaCl solutions confined between discretely charged silicon surfaces have been investigated. The electric double layer structure was found to be sensitive to the density and distribution of surface charges. Due to the discreteness of the surface charge, a slight charge inversion appeared which depended on the surface charge density, bulk concentration, and confinement. In the nanoconfined NaCl solutions concentrated from 0.2 to 4.0 M, the locations of accumulation layers for Na(+) and Cl(-) ions remained stable, but their peak values increased. The higher the concentration was, the more obvious the charge inversion appeared. In 4.0 M NaCl solution, Na(+) and Cl(-) ions show obvious alternating layered distributions which may correspond to the solidification found in experiments. By changing surface separation, the confinement had a large effect on the ionic distribution. As both surfaces approached each other, many ions and water molecules were squeezed out of the confined space. Two adjacent layers in ion or water distribution profiles can be forced closer to each other and merge together. From ionic hydration analysis, the coordination number of Na(+) ions in highly confined space was much lower than that in the bulk. PMID:27137990

  2. Massive field-theory approach to surface critical behavior in three-dimensional systems

    International Nuclear Information System (INIS)

    The massive field-theory approach for studying critical behavior in fixed space dimensions d4 n-vector model with a boundary term in the action. To make the theory UV finite in bulk dimensions 3≤d0 is required in addition to the standard mass renormalization. Adequate normalization conditions for the renormalized theory are given. This theory involves two mass parameters: the usual bulk 'mass' (inverse correlation length) m, and the renormalized surface enhancement c. Thus the surface renormalization factors depend on the renormalized coupling constant u and the ratio c/m. The special and ordinary surface transitions correspond to the limits m→0 with c/m→0 and c/m→∞, respectively. It is shown that the surface-enhancement renormalization turns into an additive renormalization in the limit c/m→∞. The renormalization factors and exponent functions with c/m=0 and c/m=∞ that are needed to determine the surface critical exponents of the special and ordinary transitions are calculated to two-loop order at d=3. The associated series expansions are analyzed by Pade-Borel summation techniques. The resulting numerical estimates for the surface critical exponents are in good agreement with recent Monte Carlo data. This is also true for the surface crossover exponent Φ, for which we obtain Φ(n=0)≅0.52 and Φ(n=1)≅0.54, values considerably lower than the previous ε-expansion estimates. (orig.)

  3. The surface layer of austempered ductile iron investment castings properties

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2009-01-01

    Full Text Available The article presents a unique process of carbonnitriding and nitriding the precision casting surfaces of austempered ductile iron. The results of the research are pointing that adequate process parameters allow to obtain multiple increase of wear resistance and a significant increase of corrosion resistance. Also, changes of cast microstructure and hardness are presented.

  4. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    The effect of tin oxide coatings on the coefficient of friction and fracture strength of glass surfaces is studied. Experiments were performed partly on commercially treated glass bottles and partly on laboratory prepared microscope slides. Coatings were applied in the laboratory by decomposition...

  5. Surface Tension Determination Using Liquid Sample Micromirror Property

    Czech Academy of Sciences Publication Activity Database

    Hošek, Jan

    Waršava: SPIE Europe, 2007 - (Cheriaux, G.; Hooker, C.; Stupka, M.), S.6584-S.6584 [Optics and Optoelectronics. Praha (CZ), 16.04.2007-19.04.2007] Institutional research plan: CEZ:AV0Z20760514 Keywords : micromirror * surface tension * measurement Subject RIV: BH - Optics, Masers, Lasers

  6. QUANTUM COHOMOLOGY OF BLOWUPS OF SURFACES AND ITS FUNCTORIALITY PROPERTY

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this article, using the WDVV equation, the author first proves that all Gromov-Witten invariants of blowups of surfaces can be computed from the Gromov-Witten invariants of itself by some recursive relations. Furthermore, it may determine the quantum product on blowups. It also proves that there is some degree of functoriality of the big quantum cohomology for a blowup.

  7. Effects of surface atomistic modification on mechanical properties of gold nanowires

    Science.gov (United States)

    Sun, Xiao-Yu; Xu, Yuanjie; Wang, Gang-Feng; Gu, Yuantong; Feng, Xi-Qiao

    2015-09-01

    Modulation of the physical and mechanical properties of nanowires is a challenging issue for their technological applications. In this paper, we investigate the effects of surface modification on the mechanical properties of gold nanowires by performing molecular dynamics simulations. It is found that by modifying a small density of silver atoms to the surface of a gold nanowire, the residual surface stress state can be altered, rendering a great improvement of its plastic yield strength. This finding is in good agreement with experimental measurements. The underlying physical mechanisms are analyzed by a core-shell nanowire model. The results are helpful for the design and optimization of advanced nanomaterial with superior mechanical properties.

  8. Behavior of the Thermodynamic Properties of Binary Mixtures near the Critical Azeotrope

    Directory of Open Access Journals (Sweden)

    Azzedine Abbaci

    2003-12-01

    Full Text Available Abstract: In this work we investigate the critical line of binary azeotropic mixtures of acetone-n-pentane. We pinpoint the abnormal behavior of the critical density line as a function of the mole fraction of one of the component and show its influence on other thermodynamic properties such as the volume, the enthalpy and the entropy.

  9. Psychometric Properties of a Korean Translation of the "Scales of Independent Behavior--Revised"

    Science.gov (United States)

    Cho, Su-Je; Paik, Eunhee; Lee, Byoung-In; Yi, Joonsuk

    2010-01-01

    This study explores the psychometric properties of data drawn from the Korean translation of the full "Scales of Independent Behavior--Revised" (SIB-R). In addition, semantic, content, conceptual, and technical equivalence are examined. The participants include 2,763 typically developing children and 406 children with intellectual disabilities…

  10. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    International Nuclear Information System (INIS)

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37±1 oC in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  11. The effect of surface treatment and position of the dental restoration on amalgam corrosion behavior

    Energy Technology Data Exchange (ETDEWEB)

    Mortazavi, V. [Isfahan Univ. of Medical Sciences, Faculty of Dentistry, Isfahan (Iran, Islamic Republic of); Fathi, M.H. [Isfahan Univ. of Technology, Materials Engineering Dept., Isfahan (Iran, Islamic Republic of)

    2003-07-01

    The aim of this research was to evaluate the effect of surface treatment, clinical operations and the condition and position of the dental restoration on amalgam corrosion behavior. Commercial amalgam alloy namely Oralloy was selected. Twenty-one amalgam samples were prepared. After triturating and condensation, the samples were divided into three groups and each group was finished by using one of three surface clinical procedures; carving, carving-burnishing, carving-burnishing-polishing. A special cylindrical mold was used in order to simulation of the interproximal areas and proximal surfaces of the dental restorations. Stainless steel matrix band was laid on the internal mold surfaces and amalgam paste was compacted in the mold. Electrochemical potentiodynamic tests were performed at a temperature of 37{+-}1 {sup o}C in physiological solution in order to determine and compare the corrosion behavior of dental amalgam samples, as an indication of biocompatibility. The results showed statistically significant differences between the mean corrosion current density values of three different groups of dental amalgam (P<0.05). The polished group possesses the lowest and the carved group shows the highest corrosion current density. The carved group shows more corrosion resistance in compare with the sample near the matrix band as an index of the proximal surfaces of restorations. It was concluded that even a simple clinical operation could effect on dental amalgam corrosion resistance. The proximal surfaces of the class II restorations are not only susceptible to concentration cell corrosion but also possess less corrosion resistance because dentist could perform no clinical surface treatment. (author)

  12. Properties of the Driving Behavior Survey Among Individuals with Motor Vehicle Accident-Related Posttraumatic Stress Disorder

    OpenAIRE

    Clapp, Joshua D.; Baker, Aaron S.; Litwack, Scott D.; Sloan, Denise M.; Beck, J. Gayle

    2013-01-01

    Data suggest anxious drivers may engage in problematic behaviors that place themselves and others at increased risk of negative traffic events. Three domains of problematic behavior – exaggerated safety/caution, performance deficits, and hostile/aggressive behaviors – previously were identified during development of the Driving Behavior Survey (DBS), a novel measure of anxiety-related behavior. Extending this research, the current study examined the psychometric properties of DBS scores among...

  13. Synthesis and surface active properties of cationic surface active agents from crude rice bran oil

    Directory of Open Access Journals (Sweden)

    El-Dougdoug, W. I. A.

    1999-10-01

    Full Text Available Cationic surfactants of 2-hidroxy-3-(2- alkylamidopolyethyl amino propane-1-triethylammonium hydroxides (ix-xuia-d were prepared from fatty acids (ia-d [palmitic, stearic, oleic, linoleic acid] and mixed fatty acids of crude rice bran oil ie [RBO]. The reaction of these acids with ethylenediamine, diethylenetriamine, triethylenetetramine andletraethylenepentamine (iia-d produced (iii-viia-d. The produced amidopolyethylamine (iii-viia-d reacted with 2-epoxypropylenetriethylammonium chloride (viii to give the cationic surfactants (ix-xiiia-d . The produced derivatives were purified and characterized by microanalysis, molecular weight determination, infra-red (IR, and proton nuclear magnetic resonance (1H NMR spectra. The surface active properties and inhibition efficiency of the prepared cationic surfactants were determined.

    Se han preparado tensioactivos catiónicos de hidróxidos de! 2-hidroxi-3-(2-alquilamidopolietilamino propano-1;trietilamonio (ix-xiiia-d a partir de los ácidos grasos (ia-d [ácido palmítico, esteárico, oleico y linoleico] y mezclas de ácidos grasos de aceite de germen de arroz crudo ie [RBO]. La reacción de estos ácidos con etilenodiamina, dietilenotriamina, trietilenotetramina y tetraetilenopentamina (iia-d produjo los compuestos (iv-viia-d . Los amidopolietilaminos producidos (iii-viia-d reaccionaron con el cloruro de 2-epoxipropilenotrietilamonio (viii para dar los tensioactivos catiónicos (ix-xiiia-d. Los derivados producidos se purificaron y caracterizaron por microanálisis, determinación del peso molecular, espectros de infrarrojo (IR y resonancia magnética nuclear de protón (1H NMR. Se determinaron las propiedades tensioactivas y la eficacia de inhibición de los tensioactivos cati

  14. Comparison of mechanical properties of surface layers with use of nanoindentation and microindentation tests

    Directory of Open Access Journals (Sweden)

    M. Zeleňák

    2012-07-01

    Full Text Available The objective of the paper is a mutual comparison of different methods for evaluation of mechanical properties of surface layers. Mechanical properties were tested with the use of nanoindentation and microindentation tests. Different loads and constant deformation speed were used in both cases. For the evaluation of mechanical properties, the AISI 304 type Chromium-Nickel steel commonly used in mechanical engineering industry was tested. Knowledge of relations and differences between nano and micromechanical properties is necessary for understanding of mechanical processes continuously occurring in surface layers during cutting processes.

  15. Modified Surface Having Low Adhesion Properties to Mitigate Insect Residue Adhesion

    Science.gov (United States)

    Wohl, Christopher J., Jr. (Inventor); Smith, Joseph G., Jr. (Inventor); Siochi, Emilie J. (Inventor); Penner, Ronald K. (Inventor)

    2016-01-01

    A process to modify a surface to provide reduced adhesion surface properties to mitigate insect residue adhesion. The surface may include the surface of an article including an aircraft, an automobile, a marine vessel, all-terrain vehicle, wind turbine, helmet, etc. The process includes topographically and chemically modifying the surface by applying a coating comprising a particulate matter, or by applying a coating and also topographically modifying the surface by various methods, including but not limited to, lithographic patterning, laser ablation and chemical etching, physical vapor phase deposition, chemical vapor phase deposition, crystal growth, electrochemical deposition, spin casting, and film casting.

  16. Surface modification of Fe304 nanoparticles and their magnetic properties

    Institute of Scientific and Technical Information of China (English)

    Hao Yan; Jian-cheng Zhang; Chen-xia You; Zhen-wei Song; Ben-wei Yu; Yue Shen

    2009-01-01

    Fe3O4 magnetic nanoparticles were synthesized by the hydrothermal method, and the influences of the surfactant sodium bis(2-ethylhexyl) sulfosuecinate (AOT) on the particles were investigated. The structure, morphology, and magnetic properties of the products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infra-red spectroscopy (FT-IR), and vibrating sample magnetometer (VSM). It is confirmed that the as-prepared nanopartieles have been modified by using the surfactant during the synthesis process. The amount of the surfactant has an effect on the size, the dispersal, and the magnetic properties of the particles. Besides, the mechanisms of the influences were also discussed.

  17. First-principle study on the surface atomic relaxation properties of sphalerite

    Science.gov (United States)

    Liu, Jian; Wen, Shu-ming; Xian, Yong-jun; Bai, Shao-jun; Chen, Xiu-min

    2012-09-01

    The surface properties of sphalerite (ZnS) were theoretically investigated using first principle calculations based on the density functional theory (DFT). DFT results indicate that both the (110) and the (220) surfaces of sphalerite undergo surface atom relaxation after geometry optimization, which results in a considerable distortion of the surface region. In the normal direction, i.e., perpendicular to the surface, S atoms in the first surface layer move outward from the bulk ( d 1), whereas Zn atoms move toward the bulk ( d 2), forming an S-enriched surface. The values of these displacements are 0.003 nm for d 1 and 0.021 nm for d 2 on the (110) surface, and 0.002 nm for d 1 and 0.011 nm for d 2 on the (220) surface. Such a relaxation process is visually interpreted through the qualitative analysis of molecular mechanics. X-ray photoelectron spectroscopic (XPS) analysis provides the evidence for the S-enriched surface. A polysulphide (S{/n 2-}) surface layer with a binding energy of 163.21 eV is formed on the surface of sphalerite after its grinding under ambient atmosphere. This S-enriched surface and the S{/n 2-} surface layer have important influence on the flotation properties of sphalerite.

  18. Mechanical and surface properties of polycarbonate - based polyurethane elastomers

    Czech Academy of Sciences Publication Activity Database

    Poreba, Rafal; Špírková, Milena; Strachota, Adam

    Praha : Institute of Macromolecular Chemistry, 2010. s. 55. ISBN 978-80-85009-63-7. [Prague Meeting on Macromolecules /74./ Contemporary Ways to Tailor-made Polymers: Modern Methods of Polymer Synthesis. 18.07.2010-22.07.2010, Prague] R&D Projects: GA ČR GAP108/10/0195 Institutional research plan: CEZ:AV0Z40500505 Keywords : polyurethane * mechanical properties * atomic force microscopy Subject RIV: CD - Macromolecular Chemistry

  19. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    Directory of Open Access Journals (Sweden)

    D. Myszka

    2013-01-01

    Full Text Available The paper presents recent developments concerning the formation of surface layer in austempered ductile iron castings. It was found thatthe traditional methods used to change the properties of the surface layer, i.e. the effect of protective atmosphere during austenitising or shot peening, are not fully satisfactory to meet the demands of commercial applications. Therefore, new ways to shape the surface layer and the surface properties of austempered ductile iron castings are searched for, to mention only detonation spraying, carbonitriding, CVD methods, etc.

  20. Study on Surface Properties for Non-polar Fluids with Density Functional Theory

    Institute of Scientific and Technical Information of China (English)

    吴畏; 陆九芳; 付东; 刘金晨; 李以圭

    2004-01-01

    The density functional theory, simplified by the local density approximation and mean-field approximation, is applied to study the surface properties of pure non-polar fluids. A reasonable long rang correction is adopted to avoid the truncation of the potential. The perturbation theory is applied to establish the equation for the phase equilibrium, in which the hard-core chain fluid is as the reference fluid and the Yukawa potential is used as the perturbation term. Three parameters, elk, d and ms, are regressed from the vapor-liquid equilibria, and the surface properties, including density profile, surface tension and local surface tension profile are predicted with these parameters.

  1. Influence of surface segregation on magnetic properties of FePt nanoparticles

    International Nuclear Information System (INIS)

    Surface segregation leads to chemical disordering in magnetic alloy nanostructures and thus could have profound impact upon the magnetic properties of these nanostructures. In this study, we used the first-principles density functional theory calculation method to determine how Pt surface segregation (exchanging interior Pt with surface Fe atoms) would affect the magnetic properties of L10 ordered FePt nanoparticles. For both cuboid and cuboctahedral FePt nanoparticles, we predicted that the Pt surface segregation process could cause a decrease in total magnetic moments, a change in (easy and/or hard) magnetization axes, and a reduction in magnetic anisotropy

  2. Nuclear surface properties and spin-orbit potential in modified derivative scalar couplings

    International Nuclear Information System (INIS)

    With the use of modified derivative scalar coupling (MDSC) model, the nuclear surface properties and the spin-orbit potential in semi-infinite nuclear matter have been investigated in the framework of relativistic Thomas-Fermi and Hartree approaches. The results show that the spin-orbit potential has been improved by the tensor coupling. However, the surface tension and the surface thickness are still to small. The effects of σ-meson mass on the surface properties and the spin-orbit potential have also been discussed

  3. Imaging elastic property of surfaces at nanoscale using atomic force microscope

    International Nuclear Information System (INIS)

    We present a simple technique to characterize and image the distribution of local elastic property using ultrasonic atomic force microscope (UAFM). We interpret the UAFM images using simple arguments. We have demonstrated the capability of the UAFM technique to image the distribution of the local elastic property of the sample surface and semi-quantitatively map the local stiffness of the sample surface using a few selected samples. The local stiffness of the sample surface was obtained by measuring the changes in the frequency of contact resonance peak values and could verify the same using force-distance measurement at the same regions on the sample surface.

  4. Intermolecular potential energy surface and thermophysical properties of ethylene oxide.

    Science.gov (United States)

    Crusius, Johann-Philipp; Hellmann, Robert; Hassel, Egon; Bich, Eckard

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C2H4O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide. PMID:25362314

  5. Intermolecular potential energy surface and thermophysical properties of ethylene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Crusius, Johann-Philipp, E-mail: johann-philipp.crusius@uni-rostock.de; Hassel, Egon [Lehrstuhl für Technische Thermodynamik, Universität Rostock, 18059 Rostock (Germany); Hellmann, Robert; Bich, Eckard [Institut für Chemie, Universität Rostock, 18059 Rostock (Germany)

    2014-10-28

    A six-dimensional potential energy hypersurface (PES) for two interacting rigid ethylene oxide (C{sub 2}H{sub 4}O) molecules was determined from high-level quantum-chemical ab initio calculations. The counterpoise-corrected supermolecular approach at the MP2 and CCSD(T) levels of theory was utilized to determine interaction energies for 10178 configurations of two molecules. An analytical site-site potential function with 19 sites per ethylene oxide molecule was fitted to the interaction energies and fine tuned to agree with data for the second acoustic virial coefficient from accurate speed of sound measurements. The PES was validated by computing the second virial coefficient, shear viscosity, and thermal conductivity. The values of these properties are substantiated by the best experimental data as they tend to fall within the uncertainty intervals and also obey the experimental temperature functions, except for viscosity, where experimental data are insufficient. Due to the lack of reliable data, especially for the transport properties, our calculated values are currently the most accurate estimates for these properties of ethylene oxide.

  6. Sustainable Development and Airport Surface Access: The Role of Technological Innovation and Behavioral Change

    Directory of Open Access Journals (Sweden)

    Bilal Qazi

    2013-04-01

    Full Text Available Sustainable development reflects an underlying tension to achieve economic growth whilst addressing environmental challenges, and this is particularly the case for the aviation sector. Although much of the aviation-related focus has fallen on reducing aircraft emissions, airports have also been under increasing pressure to support the vision of a low carbon energy future. One of the main sources of airport-related emissions is passenger journeys to and from airports (the surface access component of air travel, which is the focus of this paper. Two aspects associated with the relationship between sustainable development and airport surface access are considered. Firstly, there is an evaluation of three technological innovation options that will enable sustainable transport solutions for surface access journeys: telepresence systems to reduce drop-off/pick-up trips, techniques to improve public transport and options to encourage the sharing of rides. Secondly, the role of behavioral change for surface access journeys from a theoretical perspective, using empirical data from Manchester airport, is evaluated. Finally, the contribution of technology and behavioral intervention measures to improvements in sustainable development are discussed.

  7. Dynamic behaviors of liquid droplets on a gas diffusion layer surface: Hybrid lattice Boltzmann investigation

    Science.gov (United States)

    Wu, Jie; Huang, Jun-Jie

    2015-07-01

    Water management is one of the key issues in proton exchange membrane fuel cells. Fundamentally, it is related to dynamic behaviors of droplets on a gas diffusion layer (GDL) surface, and consequently they are investigated in this work. A two-dimensional hybrid method is employed to implement numerical simulations, in which the flow field is solved by using the lattice Boltzmann method and the interface between droplet and gas is captured by solving the Cahn-Hilliard equation directly. One or two liquid droplets are initially placed on the GDL surface of a gas channel, which is driven by the fully developed Poiseuille flow. At a fixed channel size, the effects of viscosity ratio of droplet to gas ( μ ∗ ), Capillary number (Ca, ratio of gas viscosity to surface tension), and droplet interaction on the dynamic behaviors of droplets are systematically studied. By decreasing viscosity ratio or increasing Capillary number, the single droplet can detach from the GDL surface easily. On the other hand, when two identical droplets stay close to each other or a larger droplet is placed in front of a smaller droplet, the removal of two droplets is promoted.

  8. Structure and surface properties of praseodymium modified alumina

    International Nuclear Information System (INIS)

    Mixed PrO2-Al2O3 oxides with different PrO2 content (1-20 wt.%) were prepared by wetness impregnation of γ-alumina with aqueous solution of praseodymium nitrate. The samples were characterized by different techniques, using surface adsorption-desorption of N2 (SBET), thermogravimetric analysis (TGA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), temperature-programmed reduction (TPR) and temperature-programmed desorption of CO2 (TPD-CO2). TGA and XRD showed the presence of small praseodymium oxide species on the alumina surface. XPS and DRS detected electron deficient interaction between deposited praseodymium oxide and alumina. It was observed a lower reduction temperature for supported Pr oxide species compared to that of the bulk Pr6O11. TPD-CO2 studies suggested that the deposition of Pr oxide on alumina leaded to increase of the basicity of mixed oxides.

  9. The effect of radiosterilization on surface properties of polyurethane film

    International Nuclear Information System (INIS)

    In this paper the effect of sterilization method by gamma-ray on structure and cytotoxicity of polyurethane film surface has been investigated. For this purpose reactive urethan prepolymer was synthesized by the reaction between Tdi with a mixture of Peg and castro oil (50/50, w/w). The cured prepolymer films were prepared due to the reaction of reactive prepolymer with air moister under ambient conditions. The polyurethane films were sterilized by gamma-ray (25 kGy). The surface of sterilized polyurethane film was observed by Sem and compared to that of the unsterilized film. Also, the in vitro interaction of fibroblast L 929 cells and sterilized polyurethane film was evaluated. Results showed no signs of cell toxicity

  10. Surface and catalytic properties of doped tin oxide nanoparticles

    Science.gov (United States)

    Wang, Chien-Tsung; Lai, De-Lun; Chen, Miao-Ting

    2010-10-01

    Mixed oxides composed of Zn-Sn, Ti-Sn and V-Sn were prepared by a co-precipitation method and evaluated as catalysts for methanol oxidation in an ambient fixed-bed reactor. Surface analysis by X-ray photoelectron spectroscopy (XPS) revealed an electronic interaction between dopant and Sn atoms in the oxide structure and showed the formation of surface states associated with the dopants. Oxygen vacancies were present on the Zn-doped oxide, and the oxidation of methanol to carbon oxides was favored. The Ti-doped oxide exhibited a favorable selectivity to dimethyl ether, related to the oxygen anions near Ti centers. Vanadium dopants not only dramatically increased the catalytic activity but also promoted the partial oxidation of methanol to formaldehyde. Results demonstrate that the bridging dopant-O-Sn bond acts as active sites and influences product distribution.

  11. Sterilisation properties of the Mars surface and atmospheric environment

    Science.gov (United States)

    Moreau, D.; Muller, C.

    The radiative and chemical conditions at the surface and in the lower Martian atmosphere are computed at various latitudes and seasons combining a 2D photochemical model and radiation simulations. In most situations, the solar UV B and C radiations reach the surface however, suspended dust and, in polar cases, ozone can constitute an effective UV shield. The daytime and night time concentrations of the sterilizing oxidants: /OH, H2O2 and O3 are determined, as well as the concentration of the substances which could influence the metabolism of microorganisms. The possible habitats of a remaining Mar's life as well as the possibilities of contamination by resistant earth life forms will be described.

  12. Soil surface properties affected by organic by-products

    OpenAIRE

    Pachepsky Ya.A.; Rawls W.J.; Fournier L.L.; Filgueira R.R.; Sikora L.J.

    2002-01-01

    The beneficial effects of amending soils with organic by-products include improvement of both chemical and physical factors. Very few studies have investigated changes in the soil specific surface area (SSA) after amendments with manures or composts. Soil samples were taken from plots before and after four years� application of manures, composts or nitrogen fertilizer. A corn-wheat-soybean rotation was grown. Soil samples were tested for changes in water retention at �15 bar, bu...

  13. Characterization of textural and surface properties of mesoporous metathesis catalysis

    Czech Academy of Sciences Publication Activity Database

    Balcar, Hynek; Žilková, Naděžda; Bastl, Zdeněk; Dědeček, Jiří; Hamtil, Roman; Brabec, Libor; Zukal, Arnošt; Čejka, Jiří

    Amsterdam : Elsevier B.V./Ltd, 2007 - (Xu, R.; Gao, Z.; Chen, J.; Yan, W.), s. 1145-1152 ISBN 978-0-444-53068-4. - (Studies in surface science and catalysis. Vol. 170) R&D Projects: GA AV ČR IAA4040411; GA MPO FT-TA/042 Institutional research plan: CEZ:AV0Z40400503 Keywords : catalysis * zeolites * metathesis Subject RIV: CF - Physical ; Theoretical Chemistry

  14. A study on the fabrication of superhydrophobic iron surfaces by chemical etching and galvanic replacement methods and their anti-icing properties

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Superhydrophobic iron surfaces were prepared by etching and replacement method. • The fabrication process was simple, time-saving and inexpensive. • Galvanic replacement method was more favorable to create roughness on iron surface. • The superhydrophobic iron surface showed excellent anti-icing properties. - Abstract: Hierarchical structures on iron surfaces were constructed by means of chemical etching by hydrochloric acid (HCl) solution or the galvanic replacement by silver nitrate (AgNO3) solution. The superhydrophobic iron surfaces were successfully prepared by subsequent hydrophobic modification with stearic acid. The superhydrophobic iron surfaces were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and water contact angle (WCA). The effects of reactive concentration and time on the microstructure and the wetting behavior were investigated. In addition, the anti-icing properties of the superhydrophobic iron surfaces were also studied. The FTIR study showed that the stearic acid was chemically bonded onto the iron surface. With the HCl concentration increase from 4 mol/L to 8 mol/L, the iron surface became rougher with a WCA ranging from 127° to 152°. The AgNO3 concentration had little effect on the wetting behavior, but a high AgNO3 concentration caused Ag particle aggregates to transform from flower-like formations into dendritic crystals, owing to the preferential growth direction of the Ag particles. Compared with the etching method, the galvanic replacement method on the iron surface more favorably created roughness required for achieving superhydrophobicity. The superhydrophobic iron surface showed excellent anti-icing properties in comparison with the untreated iron. The icing time of water droplets on the superhydrophobic surface was delayed to 500 s, which was longer than that of 295 s for untreated iron

  15. A study on the fabrication of superhydrophobic iron surfaces by chemical etching and galvanic replacement methods and their anti-icing properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kunquan, E-mail: likunquan1987@gmail.com; Zeng, Xingrong, E-mail: psxrzeng@gmail.com; Li, Hongqiang, E-mail: hqli1979@gmail.com; Lai, Xuejun, E-mail: msxjlai@scut.edu.cn

    2015-08-15

    Graphical abstract: - Highlights: • Superhydrophobic iron surfaces were prepared by etching and replacement method. • The fabrication process was simple, time-saving and inexpensive. • Galvanic replacement method was more favorable to create roughness on iron surface. • The superhydrophobic iron surface showed excellent anti-icing properties. - Abstract: Hierarchical structures on iron surfaces were constructed by means of chemical etching by hydrochloric acid (HCl) solution or the galvanic replacement by silver nitrate (AgNO{sub 3}) solution. The superhydrophobic iron surfaces were successfully prepared by subsequent hydrophobic modification with stearic acid. The superhydrophobic iron surfaces were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and water contact angle (WCA). The effects of reactive concentration and time on the microstructure and the wetting behavior were investigated. In addition, the anti-icing properties of the superhydrophobic iron surfaces were also studied. The FTIR study showed that the stearic acid was chemically bonded onto the iron surface. With the HCl concentration increase from 4 mol/L to 8 mol/L, the iron surface became rougher with a WCA ranging from 127° to 152°. The AgNO{sub 3} concentration had little effect on the wetting behavior, but a high AgNO{sub 3} concentration caused Ag particle aggregates to transform from flower-like formations into dendritic crystals, owing to the preferential growth direction of the Ag particles. Compared with the etching method, the galvanic replacement method on the iron surface more favorably created roughness required for achieving superhydrophobicity. The superhydrophobic iron surface showed excellent anti-icing properties in comparison with the untreated iron. The icing time of water droplets on the superhydrophobic surface was delayed to 500 s, which was longer than that of 295 s for

  16. Physicochemical changes of microbe and solid surface properties during biofilm formation

    Science.gov (United States)

    Sfaelou, Stavroula; Vakros, John; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

    2013-04-01

    .9 for PVA gel and MBBR, respectively. These values differ both from the pzc values found for PVA biocarriers (pzc = 9.4; no pzc value was obtained for MBBR as expected based on its hydrophobic nature and the absence of surface groups with acid-base behavior) and the pzc value of activated sludge (activated sludge mixed liquor: pzc = 8.0 to 8.2, solid activated sludge: pzc = 7.2 to 7.3). These results lead us to the conclusion that the formed biofilms have different acid-base behavior and properties in relation to the activated sludge and the biocarriers. This fact is in accordance to previous studies, where biofilm-associated cells can be differentiated from their suspended counterparts due to the generation of an extracellular polymeric substance (EPS) matrix. One other possible explanation is that the complicated processes of the biofilm formation can alter the distribution of different cells in the sludge compared with the cell distribution in the suspended unsupported sludge.

  17. Fatigue test results of flat plate and pipe specimens containing multiple surface flaws, and comparison with some predicted crack growth behavior

    International Nuclear Information System (INIS)

    In the report are described a series of the pipe fatigue test results, which have been conducted as a part of the pipe safety research of light water reactors. This report includes the results of flat plate test, straight pipe test, bend pipe test, and some material property tests, which have been performed through the pipe fatigue test. In the flat plate test, fatigue test of flat plate specimens with surface defects were performed to study the influence of the front free surface and the interaction of surface cracks. Based on the test results, an evaluation method for the growth of multiple surface flaws were proposed including the influence of the front free surface and interaction of cracks. In the straight pipe and bend pipe tests, fatigue test of pipes with multiple surface cracks were performed to study the behavior of fatigue crack growth in the inner surface of pipes. From the above test results, the growth behavior of surface cracks in the flat plate and in the inner surface of pipes were obtained. These growth behaviors were also compared with those obtained by the method of the ASME Boiler and Pressure Vessel Code Section XI, and the method proposed in this study to examine an applicability of those evaluation method on the problem of surface crack growth in piping components. It is shown by the test results that the method of the ASME Code gives an overconservative estimation as regard the crack coalescence, while crack shapes are incorrectly estimated resulting in an unconservative fatigue life evaluation under a certain load and boundary conditions. On the otherhand, it is shown that the method developed in this study gives a good estimation for the crack coalescence point, change in crack shape, and reasonable fatigue life. (author)

  18. Surface properties of polyaniline/nano-TiO2 composites

    International Nuclear Information System (INIS)

    Polyaniline/nano-TiO2 composite was prepared by polyaniline for the surface modification of nano-TiO2 particles, and was characterized via Fourier-transform infrared spectra, UV-Vis-NIR spectrophotometer, wide-angle X-ray diffraction, thermogravimetric analysis and transmission electron microscope, as well as conductivity. Surface area, total pore volume and pore size distribution of nano-TiO2 particles and polyaniline/nano-TiO2 composite particles were also measured. The results of spectroanalysis illustrate that polyaniline and nano-TiO2 particles are not simply blended or mixed up. There is a strong interaction between polyaniline macromolecule and nano-TiO2 particles. Synthesized polyaniline was deposited on the surface of nano-TiO2 particles, forming a core-shell structure. The dimension of polyaniline/nano-TiO2 composite particles is in the range 25-40 nm. Polyaniline/nano-TiO2 composite contains 38% conducting polyaniline by mass, for which conductivity reaches 0.75 S cm-1 at 25 deg. C

  19. Electroless nickel plated graphite fibers and surface behavior in Gr(Ni)/6061Al composite

    Institute of Scientific and Technical Information of China (English)

    WANG Chun-yu; WU Gao-hui; ZHANG Qiang; ZHANG Yun-he; XIU Zi-yang; CHEN Guo-qin

    2006-01-01

    The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni)/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating were studied. The optimum process of electroless Ni-P plating included: burning to get rid of glue→degreasing→neutralization→acidulating→sensitizing→activation→electroless plating. The surface analysis results show that the electroless nickel plating can diffuse into the graphite fiber surface during the squeeze casting, and the Ni-P coating and aluminum alloys can produce brittle phase NiAl3 or NiAl. The X-ray diffraction(XRD) results indicate that Al4C3 is so little that no Al4C3 peaks are found, and the harmful hl4C3 can be decreased by the electroless plating Ni-P coating. The coating improves the interfacial bonding of continuous graphite fibers reinforced aluminum matrix composites.

  20. Fabrication and tribological behavior of superhydrophobic zinc surface based on oleic acid

    International Nuclear Information System (INIS)

    A zinc substrate was firstly immersed in an aqueous solution of N, N-dimethylformamide (DMF) solution and then chemically modified with oleic acid to generate a superhydrophobic surface. The morphological features, chemical composition and superhydrophobicity of the resultant superhydrophobic surface were analyzed by means of scanning electron microscopy, Fourier transform infrared microscopy and water contact angle (WCA) measurements, respectively, and the tribological behavior of films was evaluated by sliding the superhydrophobic films against a steel ball under 0.5 N normal load using a reciprocating ball-on-plate tribo-tester. It was found that the as-obtained superhydrophobic surface on the roughened (oxidized) zinc substrate had a WCA as high as 155°, and effectively reduced friction and largely increased antiwear life, due to the combined beneficial effects of nanotexturing of DMF treatment and nanolubrication of self-assembled oleic acid overcoat.

  1. Group Theory Analysis of Free Convective Boundary—Layer Behavior at a Stretching Surface

    Institute of Scientific and Technical Information of China (English)

    JunmeiShi; XueziXu; 等

    1995-01-01

    In the present study,free convection and heat transfer behavior of electrically conducting fluid in the boundary layer over a vertical continuously stretching surface is investigated.The effects of free convection,magnetic field,suction/blowing at the surface and the stretching speed of the surface on the flow and heat transfer characteristics are considered.By applying one-parametric group theory to analysis of the problem,a similarity solution is found.The governing equations of continuity,momentum and energy are solved numerically by a fourth-order Runge-Kutta scheme.The numerical results.which are obtained for the flow and heat transfer characteristics,reveal the influences of the parameters.

  2. Hydrogen and oxygen behaviors on Porous-Si surfaces observed using a scanning ESD ion microscope

    International Nuclear Information System (INIS)

    A scanning electron-stimulated desorption (ESD) ion microscope (SESDIM) measured the 2-D images of hydrogen and oxygen distribution on solid surfaces. A primary electron beam at 600 eV, with a pulse width of 220 ns, resulted in ion yields of H+ and O+. This SESDIM is applied to the surface analysis of Porous-Si (Po-Si) partially covered with SiN films. During the heating of a specimen of the Po-Si at 800 deg. C under ultra-high-vacuum (UHV) conditions, the components of the surface materials were moved or diffused by thermal decomposition accompanied by a redistribution of hydrogen and oxygen. After cyclic heating of above 800 deg. C, the dynamic behaviors of H+ and O+ accompanied by the movements of the SiN layers were observed as images of H+ and O+. This was because the H+ and O+ ions have been identified as composite materials by their kinetic energies

  3. Atomic interactions at the (100) diamond surface and the impact of surface and interface changes on the electronic transport properties

    Science.gov (United States)

    Deferme, Wim

    Centuries and centuries already, diamond is a material that speaks to ones imagination. Till the 18th century it was only mined in India, after it was also found in Brazil and South-Africa. But along the fascinating properties of diamond, it is also a very interesting material for industry. After the discovery at the end of the 18th century that diamond consists of carbon, it took until the 50's of the previous century before research groups from Russia, Japan and the USA were able to reproduce the growth process of diamond. In 1989 it was discovered that the surface of intrinsic, insulation diamond can be made conductive by hydrogenating the surface. It was clear that not only hydrogen at the surface but also the so called "adsorbates" were responsible for this conductivity. It was still not completely clear what was the influence of other species (like oxygen) on the mechanism of surface conductivity and therefore in this thesis the influence of oxygen on the electronic transport properties of atomically flat diamond are researched. Besides the growth of atomically flat diamond with the use of CVD (chemical vapour deposition) en the study of the grown surfaces with characterising techniques such as AFM (atomic force microscopy) and STM (scanning tunnelling microscopy), the study of the surface treatment with plasma techniques is the main topic of this thesis. The influence of oxygen on the surface conductivity is studied and with the ToF (Time-of-Flight) technique the transport properties of the freestanding diamond are examined. With a short laserflash, electrons and holes are created at the diamond/aluminium interface and due to an electric field (up to 500V) the charge carriers are translated to the back contact. In this way the influence of the surface and the changes at the aluminum contacts is studied leading to very interesting results.

  4. Comparison of Different Global Information Sources Used in Surface Radiative Flux Calculation: Radiative Properties of the Surface

    Science.gov (United States)

    Zhang, Yuanchong; Rossow, William B.; Stackhouse, Paul W., Jr.

    2007-01-01

    Direct estimates of surface radiative fluxes that resolve regional and weather-scale variabilty over the whole globe with reasonable accuracy have only become possible with the advent of extensive global, mostly satellite, datasets within the past couple of decades. The accuracy of these fluxes, estimated to be about 10-15 W per square meter is largely limited by the accuracy of the input datasets. The leading uncertainties in the surface fluxes are no longer predominantly induced by clouds but are now as much associated with uncertainties in the surface and near-surface atmospheric properties. This study presents a fuller, more quantitative evaluation of the uncertainties for the surface albedo and emissivity and surface skin temperatures by comparing the main available global datasets from the Moderate-Resolution Imaging Spectroradiometer product, the NASA Global Energy and Water Cycle Experiment Surface Radiation Budget project, the European Centre for Medium-Range Weather Forecasts, the National Aeronautics and Space Administration, the National Centers for Environmental Prediction, the International Satellite Cloud Climatology Project (ISCCP), the Laboratoire de Meteorologie Dynamique, NOAA/NASA Pathfinder Advanced Very High Resolution Radiometer project, NOAA Optimum Interpolation Sea Surface Temperature Analysis and the Tropical Rainfall Measuring Mission (TRMM) Microwave Image project. The datasets are, in practice, treated as an ensemble of realizations of the actual climate such that their differences represent an estimate of the uncertainty in their measurements because we do not possess global truth datasets for these quantities. The results are globally representative and may be taken as a generalization of our previous ISCCP-based uncertainty estimates for the input datasets. Surface properties have the primary role in determining the surface upward shortwave (SW) and longwave (LW) flux. From this study, the following conclusions are obtained

  5. The effect of ultrasonic nanocrystalline surface modification on the high-frequency fretting wear behavior of AISI304 steel.

    Science.gov (United States)

    Cho, In-Shik; Lee, Chang-Soon; Amanov, Auezhan; Pyoun, Young-Shik; Park, In-Gyu

    2011-01-01

    The fact that one of fundamental characteristics of fretting is the very small sliding amplitude dictates the unique feature of wear mechanism. Ultrasonic Nanocrystalline Surface Modification (UNSM) technology was applied in order to investigate its effect on the high-frequency fretting wear behavior of AISI304 steel. Its influence on the fretting wear is also reported in this paper with these treated and untreated samples. UNSM delivers force onto the workpiece surface 20,000 times per second with 1,000 to 4,000 contact counts per square millimeter. UNSM creates homogenous nanocrystalline structures as well on the surface. UNSM process is expected to eliminate or significantly retard the formation of fretting wear. Nanocrystalline structure generation after UNSM has been reported to produce its unique structure and to offer a variety of beneficial properties compared to conventionally treated materials. A deformed layer of 220 microm exhibits high dislocation density, where top layer transformed to a nanostructure of the grain size in 23 nm and mechanical twins were observed. Deformation-induced martensite was observed to form at the intersections of mechanical twins, whose volume fraction has increased up to 38.4% and wear loss rate at 800,000 cycles has decreased by 40%. In this paper, experimental results are discussed to elucidate potential mechanism of high-frequency fretting wear. PMID:21446536

  6. Enhanced super-hydrophobic and switching behavior of ZnO nanostructured surfaces prepared by simple solution--immersion successive ionic layer adsorption and reaction process.

    Science.gov (United States)

    Suresh Kumar, P; Sundaramurthy, J; Mangalaraj, D; Nataraj, D; Rajarathnam, D; Srinivasan, M P

    2011-11-01

    A simple and cost-effective successive ionic layer adsorption and reaction (SILAR) method was adopted to fabricate hydrophobic ZnO nanostructured surfaces on transparent indium-tin oxide (ITO), glass and polyethylene terephthalate (PET) substrates. ZnO films deposited on different substrates show hierarchical structures like spindle, flower and spherical shape with diameters ranging from 30 to 300 nm. The photo-induced switching behaviors of ZnO film surfaces between hydrophobic and hydrophilic states were examined by water contact angle and X-ray photoelectron spectroscopy (XPS) analysis. ZnO nanostructured films had contact angles of ~140° and 160°±2 on glass and PET substrates, respectively, exhibiting hydrophobic behavior without any surface modification or treatment. Upon exposure to ultraviolet (UV) illumination, the films showed hydrophilic behavior (contact angle: 15°±2), which upon low thermal stimuli revert back to its original hydrophobic nature. Such reversible and repeatable switching behaviors were observed upon cyclical exposure to ultraviolet radiation. These biomimetic ZnO surfaces exhibit good anti-reflective properties with lower reflectance of 9% for PET substrates. Thus, the present work is significant in terms of its potential application in switching devices, solar coatings and self-cleaning smart windows. PMID:21831394

  7. Electronic surface properties of SrTiO3 derived from a surface photovoltage study

    Science.gov (United States)

    Beyreuther, E.; Becherer, J.; Thiessen, A.; Grafström, S.; Eng, L. M.

    2013-06-01

    In the past, surface photovoltage (SPV) analysis has been successfully applied to derive the electronic defect status of a number of wide-bandgap semiconductor surfaces. Here, the method is applied to the model perovskite strontium titanate, whose SPV phenomena are comprehensively studied over seven decades of excitation-light intensity. The SPV was recorded by a Kelvin probe setup as a function of wavelength in order to extract the energetic positions of electronic surface states within the bandgap. At selected wavelengths addressing distinct surface states, SPV transients were measured as a function of light intensity and temperature. Several models known from the literature were used to estimate and cross check surface state parameters such as surface state densities, capture cross sections for photons and electrons, and the surface band bending in the dark and under illumination. In contrast to other wide-bandgap materials, SPV transients of SrTiO3 exhibit highly complex shapes, i.e. they (i) show signatures of multiple carrier transitions, (ii) mixtures of surface and bulk contributions, as well as (iii) both ex- and intrinsic SPV processes.

  8. Galileo PPR Observations of Europa: Correlations of Thermophysical Properties with Surface Features

    Science.gov (United States)

    Rathbun, J. A.; Spencer, J. R.; Howett, C. J. A.

    2012-03-01

    We will compare Galileo Photopolarimeter-Radiometer (PPR) temperature data to thermal models and a geologic map to determine if there are correlations between thermophysical properties and surface features.

  9. Effect of Surface Pretreatment on Adhesive Properties of Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    Jinsheng ZHANG; Xuhui ZHAO; Yu ZUO; Jinping XIONG; Xiaofeng ZHANG

    2008-01-01

    The lap-shear strength and durability of adhesive bonded AI alloy joints with different pretreatments were studied by the lap-shear test and wedge test. The results indicate that the maximum lap-shear strength and durability of the bonding joints pretreated by different processes are influenced by the grade of abrasive papers and can be obviously improved by phosphoric acid anodizing. Alkali etching can obviously improve the durability of bonding joints although it slightly influences the maximum lap-shear strength. The process which is composed of grit-finishing, acetone degreasing, alkali etching and phosphoric acid anodizing, provides a better adhesive bonding property of AI alloy.

  10. The surface properties of nanoparticles determine the agglomeration state and the size of the particles under physiological conditions

    Directory of Open Access Journals (Sweden)

    Christoph Bantz

    2014-10-01

    Full Text Available Due to the recent widespread application of nanomaterials to biological systems, a careful consideration of their physiological impact is required. This demands an understanding of the complex processes at the bio–nano interface. Therefore, a comprehensive and accurate characterization of the material under physiological conditions is crucial to correlate the observed biological impact with defined colloidal properties. As promising candidates for biomedical applications, two SiO2-based nanomaterial systems were chosen for extensive size characterization to investigate the agglomeration behavior under physiological conditions. To combine the benefits of different characterization techniques and to compensate for their respective drawbacks, transmission electron microscopy, dynamic light scattering and asymmetric flow field-flow fractionation were applied. The investigated particle systems were (i negatively charged silica particles and (ii poly(organosiloxane particles offering variable surface modification opportunities (positively charged, polymer coated. It is shown that the surface properties primarily determine the agglomeration state of the particles and therefore their effective size, especially under physiological conditions. Thus, the biological identity of a nanomaterial is clearly influenced by differentiating surface properties.

  11. Hydrophobic and electrostatic cell surface properties of thermophilic dairy streptococci.

    Science.gov (United States)

    van der Mei, H C; de Vries, J; Busscher, H J

    1993-12-01

    Microbial adhesion to hydrocarbons (MATH) and microelectrophoresis were done in 10 mM potassium phosphate solutions to characterize the surfaces of thermophilic dairy streptococci, isolated from pasteurizers. Regardless of whether they were grown (in M17 broth) with lactose, sucrose, or glucose added, strains were relatively hydrophilic (showing low initial removal rates by hexadecane) and slightly negatively charged. A tendency exists for cells grown with sucrose added to be more hydrophilic than cells grown with glucose or lactose added. Also, the lowest isoelectric points, i.e., the pH values for which the zeta potentials are zero, were measured for strains with glucose added to the growth medium. The isoelectric points for the strains were all rather high, between pH 3 and 5, indicative of protein-rich surfaces, although X-ray photoelectron spectroscopy did not measure excessively large amounts of nitrogen on the cell surfaces. Both MATH and microelectrophoresis were done as a function of pH. Maxima in hydrophobicity were observed at certain pH values. Usually these pH values were in the range of the isoelectric points of the cells. Thus it appears that MATH measures an interplay of hydrophobicity and electrostatic interactions. MATH measures solely hydrophobicity only when electrostatic interactions are absent, i.e., close to the isoelectric points of the cells. Considering that these thermophilic streptococci are all rather hydrophilic, a possible pathway to prevent fouling in the pasteurization process might be to render the heat exchanger plates of the pasteurizer more hydrophobic. PMID:16349127

  12. Microstructure and surface properties of lignocellulosic-based activated carbons

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Garcia, P., E-mail: pegonzal@quim.ucm.es [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040, Madrid (Spain); Centeno, T.A. [Instituto Nacional del Carbon-CSIC, Apartado 73, E-33080 Oviedo (Spain); Urones-Garrote, E. [Centro Nacional de Microscopia Electronica, Universidad Complutense, E-28040, Madrid (Spain); Avila-Brande, D.; Otero-Diaz, L.C. [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, E-28040, Madrid (Spain)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Activated carbons were produced by KOH activation at 700 Degree-Sign C. Black-Right-Pointing-Pointer The observed nanostructure consists of highly disordered graphene-like layers with sp{sup 2} bond content Almost-Equal-To 95%. Black-Right-Pointing-Pointer Textural parameters show high surface area ( Almost-Equal-To 1000 m{sup 2}/g) and pore width of 1.3-1.8 nm. Black-Right-Pointing-Pointer Specific capacitance reaches values as high as 161 F/g. - Abstract: Low cost activated carbons have been produced via chemical activation, by using KOH at 700 Degree-Sign C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp{sup 2} content Almost-Equal-To 95% and average mass density of 1.65 g/cm{sup 3} (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m{sup 2}/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm{sup 2}) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

  13. Properties of water surface discharge at different pulse repetition rates

    Czech Academy of Sciences Publication Activity Database

    Ruma, R.; Hosseini, S.H.R.; Yoshihara, K.; Akiyama, M.; Sakugawa, T.; Lukeš, Petr; Akiyama, H.

    2014-01-01

    Roč. 116, č. 12 (2014), s. 123304-123304. ISSN 0021-8979 Grant ostatní: Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M100431203 Institutional support: RVO:61389021 Keywords : plasma in air * water surface discharge * pulse frequency * hydrogen peroxide * organic dye Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.183, year: 2014 http://dx.doi.org/ 10.1063/1.4896266

  14. On surface properties of two-dimensional percolation clusters

    OpenAIRE

    de Queiroz, S. L. A.

    1995-01-01

    The two-dimensional site percolation problem is studied by transfer-matrix methods on finite-width strips with free boundary conditions. The relationship between correlation-length amplitudes and critical indices, predicted by conformal invariance, allows a very precise determination of the surface decay-of-correlations exponent, $\\eta_s = 0.6664 \\pm 0.0008$, consistent with the analytical value $\\eta_s = 2/3$. It is found that a special transition does not occur in the case, corroborating ea...

  15. Improvement of Mechanical Properties on a Surface of Bulk Ceramics

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Kraus, L.

    Trollhättan : University West, 2009 - (Sudarshan, T.; Nylen, P.), s. 247-254 ISBN 978-0-9817065-1-1. [International Conference on Surface Modification Technologies SMT22/22./. Trollhättan (SE), 22.09.2008-24.09.2008] R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Bulk ceramics * plasma post-treatment * diode laser * wear resistance * mechanical testing Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  16. Physical and mechanical properties of maraging steels and exoemission from their surfaces

    International Nuclear Information System (INIS)

    Certain physicomechanical properties of maraging steel 08Kh15N5D2T (VNS-2), subjected to ageing in the temperature range 100-500 deg C, and exoelectron emission from its surface are investigated. Strength and yield limits, relative narrowing, the value of relaxation effect after tension are determined. Electron properties of the aged specimen surface were evaluated using the methods of exoemission, and changes in chemical composition - by Auger spectroscopy

  17. Permeation Properties and Pore Structure of Surface Layer of Fly Ash Concrete

    OpenAIRE

    Jun Liu; Qiwen Qiu; Feng Xing; Dong Pan

    2014-01-01

    This paper presents an experimental study on the nature of permeation properties and pore structure of concrete surface layers containing fly ash. Concretes containing different dosages of fly ash as a replacement for cement (15% and 30% by weight of total cement materials, respectively) were investigated. Concrete without any fly ash added was also employed as the reference specimen. Laboratory tests were conducted to determine the surface layer properties of concrete including chloride tran...

  18. Surface properties of distinct nanofibrillated celluloses assessed by inverse gas chromatography

    OpenAIRE

    Gamelas, José A.F.; Pedrosa, Jorge; Lourenço, Ana F.; Ferreira, Paulo J.

    2014-01-01

    The adhesion and surface properties of nanocelluloses are an important issue to consider when using this material for composites production, in food packaging or coatings, as well as for determining the influence of added functional groups. In the present work, the surface properties of two nanofibrillated celluloses obtained by mild 2,2,6,6-tetramethylpiperidine-1- oxyl radical (TEMPO)-mediated oxidation with distinct mechanical treatment intensity in a homogenizer (5 and 15 pass...

  19. Effect of activation agents on the surface chemical properties and desulphurization performance of activated carbon

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Flue gas pollution is a serious environmental problem that needs to be solved for the sustainable development of China.The surface chemical properties of carbon have great influence on its desulphurization performance.A series of activated carbons (ACs) were prepared using HNO3,H2O2,NH3·H2O and steam as activation agents with the aim to introduce functional groups to carbon surface in the ACs preparation process.The ACs were physically and chemically characterized by iodine and SO2 adsorption,ultimate analysis,Boehm titration,and temperature-programmed reduction (TPR).Results showed that the iodine number and desulphurization capacity of NH3·H2O activated carbon (AC-NH3) increase with both activation time,and its desulphurization capacity also increases with the concentration of activation agent.However,HNO3 activated carbon (AC-HNO3) and H2O2 activated carbon (AC-H2O2) exhibit more complex behavior.Only their iodine numbers increase monotonously with activation time.Compared with steam activated AC (AC-H2O),the nitrogen content increases 0.232% in AC-NH3 and 0.077% in AC-HNO3.The amount of total basic site on AC-HNO3 is 0.19 mmol·g-1 higher than that on AC-H2O.H2O2 activation introduces an additional 0.08 mmol·g-1 carboxyl groups to AC surface than that introduced by steam activation.The desulphurization capacity of ACs in simulate flue gas desulphurization decreases as follows: AC-NH3 > AC-HNO3 > AC-H2O2 > AC-H2O.This sequence is in accord with the SO2 catalytic oxidation/oxidation ratio in the absence of oxygen and the oxidation property reflected by TPR.In the presence of oxygen,all adsorbed SO2 on ACs can be oxidized into SO3.The desulphurization capacity increases differently according to the activation agents;the desulphurization capacity of AC-NH3 and AC-HNO3 improves by 4.8 times,yet AC-H2O increases only by 2.62 as compared with the desulphurization of corresponding ACs in absence of oxygen.

  20. Structure-property relations and modeling of small crack fatigue behavior of various magnesium alloys

    Science.gov (United States)

    Bernard, Jairus Daniel

    Lightweight structural components are important to the automotive and aerospace industries so that better fuel economy can be realized. Magnesium alloys in particular are being examined to fulfill this need due to their attractive stiffness- and strength-to-weight ratios when compared to other materials. However, when introducing a material into new roles, one needs to properly characterize its mechanical properties. Fatigue behavior is especially important considering aerospace and automotive component applications. Therefore, quantifying the structure-property relationships and accurately predicting the fatigue behavior for these materials are vital. This study has two purposes. The first is to quantify the structure-property relationships for the fatigue behavior in an AM30 magnesium alloy. The second is to use the microstructural-based MultiStage Fatigue (MSF) model in order to accurately predict the fatigue behavior of three magnesium alloys: AM30, Elektron 21, and AZ61. While some studies have previously quantified the MSF material constants for several magnesium alloys, detailed research into the fatigue regimes, notably the microstructurally small crack (MSC) region, is lacking. Hence, the contribution of this work is the first of its kind to experimentally quantify the fatigue crack incubation and MSC regimes that are used for the MultiStage Fatigue model. Using a multi-faceted experimental approach, these regimes were explored with a replica method that used a dual-stage silicone based compound along with previously published in situ fatigue tests. These observations were used in calibrating the MultiStage Fatigue model.