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Sample records for behavior surface properties

  1. 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.

  2. d-α-tocopherol nanoemulsions: Size properties, rheological behavior, surface tension, osmolarity and cytotoxicity

    Directory of Open Access Journals (Sweden)

    M.C. Teixeira

    2017-02-01

    Full Text Available The aim of this study was the assessment of the physicochemical stability of d-α-tocopherol formulated in medium chain triglyceride nanoemulsions, stabilized with Tween®80 and Lipoid®S75 as surfactant and co-surfactant, respectively. d-α-tocopherol was selected as active ingredient because of its well-recognized interesting anti-oxidant properties (such as radical scavenger for food and pharmaceutical industries. A series of nanoemulsions of mean droplet size below 90 nm (polydispersity index < 0.15 have been produced by high-pressure homogenization, and their surface electrical charge (zeta potential, pH, surface tension, osmolarity, and rheological behavior, were characterized as a function of the d-α-tocopherol loading. In vitro studies in Caco-2 cell lines confirmed the safety profile of the developed nanoemulsions with percentage of cell viability above 90% for all formulations.

  3. Mechanical Properties and Tribological Behavior of In Situ NbC/Fe Surface Composites

    Science.gov (United States)

    Cai, Xiaolong; Zhong, Lisheng; Xu, Yunhua

    2016-11-01

    The mechanical properties and tribological behavior of the niobium carbide (NbC)-reinforced gray cast iron surface composites prepared by in situ synthesis have been investigated. Composites are comprised of a thin compound layer and followed by a deep diffusion zone on the surface of gray cast iron. The graded distributions of the hardness and elastic modulus along the depth direction of the cross section of composites form in the ranges of 6.5-20.1 and 159.3-411.2 GPa, respectively. Meanwhile, dry wear tests for composites were implemented on pin-on-disk equipment at sliding speed of 14.7 × 10-2 m/s and under 5 or 20 N, respectively. The result indicates that tribological performances of composites are considerably dependent on the volume fraction and the grain size of the NbC as well as the mechanical properties of the matrices in different areas. The surface compound layer presents the lowest coefficient of friction and wear rate, and exhibits the highest wear resistance, in comparison with diffusion zone and substrate. Furthermore, the worn morphologies observed reveal the dominant wear mechanism is abrasive wear feature in compound layer and diffusion zone.

  4. Mechanical Properties and Tribological Behavior of In Situ NbC/Fe Surface Composites

    Science.gov (United States)

    Cai, Xiaolong; Zhong, Lisheng; Xu, Yunhua

    2017-01-01

    The mechanical properties and tribological behavior of the niobium carbide (NbC)-reinforced gray cast iron surface composites prepared by in situ synthesis have been investigated. Composites are comprised of a thin compound layer and followed by a deep diffusion zone on the surface of gray cast iron. The graded distributions of the hardness and elastic modulus along the depth direction of the cross section of composites form in the ranges of 6.5-20.1 and 159.3-411.2 GPa, respectively. Meanwhile, dry wear tests for composites were implemented on pin-on-disk equipment at sliding speed of 14.7 × 10-2 m/s and under 5 or 20 N, respectively. The result indicates that tribological performances of composites are considerably dependent on the volume fraction and the grain size of the NbC as well as the mechanical properties of the matrices in different areas. The surface compound layer presents the lowest coefficient of friction and wear rate, and exhibits the highest wear resistance, in comparison with diffusion zone and substrate. Furthermore, the worn morphologies observed reveal the dominant wear mechanism is abrasive wear feature in compound layer and diffusion zone.

  5. 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).

  6. 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.

  7. 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

  8. Universal quantifier derived from AFM analysis links cellular mechanical properties and cell-surface integration forces with microbial deposition and transport behavior.

    Science.gov (United States)

    Li, Yueyun; Wang, Xin; Onnis-Hayden, Annalisa; Wan, Kai-tak; Gu, April Z

    2014-01-01

    In this study, we employed AFM analysis combined with mathematical modeling for quantifying cell-surface contact mechanics and magnitude and range of cell-surface interaction forces for seven bacterial strains with a wide range of cell morphology, dimension, and surface characteristics. Comprehensive cell-surface characterization including surface charge, extracellular polymeric substance content, hydrophobicity, and cell-cell aggregation analyses were performed. Flow-through column tests were employed to determine the attachment efficiency and deposition-transport behavior of these bacterial strains. No statistically significant correlation between attachment efficiency and any single-cell surface property was identified. Single-cell characterization by atomic force microscopy (AFM) yielded the mechanical deformation and elastic modulus, penetration resistance to AFM probe penetration by cellular surface substances (CSS), range and magnitude of the repulsive-attractive intersurface forces, and geometry of each strain. We proposed and derived a universal dimensionless modified Tabor's parameter to integrate all these properties that account for their collective behavior. Results showed that the Tabor parameter derived from AFM analysis correlated well with experimentally determined attachment efficiency (α), which therefore is able to link microscale cell-surface properties with macroscale bacterial transport behavior. Results suggested that the AFM tests performed between a single cell and a surface captured the key quantities of the interactions between the cell and the surface that dictate overall cell attachment behavior. Tabor's parameter therefore can be potentially incorporated into the microbial transport model.

  9. Surface properties and wetting behavior of liquid Ag-Sb-Sn alloys

    Directory of Open Access Journals (Sweden)

    Sklyarchuk V.

    2012-01-01

    Full Text Available Surface tension and density measurements of liquid Ag-Sb-Sn alloys were carried out over a wide temperature range by using the sessile drop method. The surface tension experimental data were analyzed by the Butler thermodynamic model in the regular solution approximation. The wetting characteristics of these alloys on Cu and Ni substrates have been also determined. The new experimental results were compared with the calculated values as well as with data available in the literature.

  10. Corrosion performance of reinforced mortar in the presence of polymeric nano-aggregates: electrochemical behavior, surface analysis, and properties of the steel/cement paste interface

    OpenAIRE

    Hu, J; Koleva, D. A.; Breugel, K. van

    2012-01-01

    This study reports on the effect of admixed polyethylene oxide-b-polystyrene (PEO113-b-PS70)micelles on corrosion behavior of reinforced mortar. The electrochemical measurement shows that the corrosion performance of the reinforcing steel was not significantly improved. However, surface analysis and microstructural investigation at the steel/cement paste interface reveal that the admixed micelles lead to a steel surface layer with enhanced barrier properties in terms of morphology and composi...

  11. 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.

  12. Surface electrical properties experiment

    Science.gov (United States)

    Simmons, Gene; Strangway, David; Annan, Peter; Baker, Richard G.; Bannister, Lawrence; Brown, Raymon; Cooper, William; Cubley, Dean; deBettencourt, Joseph; England, Anthony W.; Groener, John; Kong, Jin-Au; LaTorraca, Gerald; Meyer, James; Nanda, Ved; Redman, David; Rossiter, James; Tsang, Leung; Urner, Joseph; Watts, Raymond

    1973-01-01

    The surface electrical properties (SEP) experiment was used to explore the subsurface material of the Apollo 17 landing site by means of electromagnetic radiation. The experiment was designed to detect electrical layering, discrete scattering bodies, and the possible presence of water. From the analysis of the data, it was expected that values of the electrical properties (dielectric constant and loss tangent) of lunar material in situ would be obtained.

  13. 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...

  14. Salt effects on the air/solution interfacial properties of PEO-containing copolymers: equilibrium, adsorption kinetics and surface rheological behavior.

    Science.gov (United States)

    Llamas, Sara; Mendoza, Alma J; Guzmán, Eduardo; Ortega, Francisco; Rubio, Ramón G

    2013-06-15

    Lithium cations are known to form complexes with the oxygen atoms of poly(oxyethylene) chains. The effect of Li(+) on the surface properties of three block-copolymers containing poly(oxyethylene) (PEO) have been studied. Two types of copolymers have been studied, a water soluble one of the pluronic family, PEO-b-PPO-b-PEO, PPO being poly(propyleneoxyde), and two water insoluble ones: PEO-b-PS and PEO-b-PS-b-PEO, PS being polystyrene. In the case of the pluronic the adsorption kinetics, the equilibrium surface tension isotherm and the aqueous/air surface rheology have been measured, while for the two insoluble copolymers only the surface pressure and the surface rheology have been studied. In all the cases two different Li(+) concentrations have been used. As in the absence of lithium ions, the adsorption kinetics of pluronic solutions shows two processes, and becomes faster as [Li(+)] increases. The kinetics is not diffusion controlled. For a given pluronic concentration the equilibrium surface pressure increases with [Li(+)], and the isotherms show two surface phase transitions, though less marked than for [Li(+)]=0. A similar behavior was found for the equilibrium isotherms of PEO-b-PS and PEO-b-PS-b-PEO. The surface elasticity of these two copolymers was found to increase with [Li(+)] over the whole surface concentration and frequency ranges studied. A smaller effect was found in the case of the pluronic solutions. The results of the pluronic solutions were modeled using a recent theory that takes into account that the molecules can be adsorbed at the surface in two different states. The theory gives a good fit for the adsorption kinetics and a reasonably good prediction of the equilibrium isotherms for low and intermediate concentrations of pluronic. However, the theory is not able to reproduce the isotherm for [Li(+)]=0. Only a semi-quantitative prediction of the surface elasticity is obtained for [pluronic]≤1×10(-3) mM.

  15. 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 .

  16. 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.

  17. 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.

  18. Surface properties and dye loading behavior of Zn{sub 2}SnO{sub 4} nanoparticles hydrothermally synthesized using different mineralizers

    Energy Technology Data Exchange (ETDEWEB)

    Annamalai, Alagappan; Eo, Yang Dam [Department of Advanced Technology Fusion, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701 (Korea, Republic of); Im, Chan [Department of Chemistry, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701 (Korea, Republic of); Lee, Man-Jong, E-mail: leemtx@konkuk.ac.kr [Department of Advanced Technology Fusion, Konkuk University, 1 Hwayang-dong, Kwangjin-gu, Seoul 143-701 (Korea, Republic of)

    2011-10-15

    We present for the first time the influence of different mineralizers on the isoelectric point (IEP) of zinc stannate (Zn{sub 2}SnO{sub 4}) nanoparticles hydrothermally prepared using three different mineralizers, viz., Na{sub 2}CO{sub 3}, KOH and tert-butyl amine, and the effect of the IEPs on the dye loading behavior of Zn{sub 2}SnO{sub 4} based photoelectrodes in dye sensitized solar cells (DSSCs). To produce highly crystalline, uniform sized Zn{sub 2}SnO{sub 4} nanoparticles, hydrothermal processing parameters, such as reaction temperature, time, and the mineralizers used have been critically adjusted. The structural and morphological features of the as-synthesized Zn{sub 2}SnO{sub 4} nanoparticles have been observed using both scanning and transmission electron microscopy. For the surface state characterization of shape- and size-controlled Zn{sub 2}SnO{sub 4} nanoparticles, the IEPs of Zn{sub 2}SnO{sub 4} surfaces were determined through zeta potential measurements. The IEPs were found to be 5.7, 7.4 and 8.1 for Zn{sub 2}SnO{sub 4} nanoparticles formed using Na{sub 2}CO{sub 3}, KOH and tert-butyl amine, respectively, suggesting that the surface properties of Zn{sub 2}SnO{sub 4} nanoparticles can be manipulated through the choice of the mineralizers used during the hydrothermal reaction. The amount of N719 dye loading on the surfaces of Zn{sub 2}SnO{sub 4} electrodes having different IEPs was also evaluated. It was revealed that the higher the IEP, the higher the dye loading amount, which means that the IEP mainly affects the dye loading at the dye-metal oxide interface. - Highlights: {yields} The effect of various mineralizers on the isoelectric point of Zn{sub 2}SnO{sub 4} was discussed. {yields} The IEP of Zn{sub 2}SnO{sub 4} can be modified by the choice of mineralizer. {yields} Change in IEP affects the surface properties and the morphology of Zn{sub 2}SnO{sub 4} particles. {yields} Modified surface affects the N719 dye loading behaviour of the Zn{sub 2

  19. Wetting properties of nanostructured surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ramos-Canut, S. [Laboratoire de Physique de la Matiere Condensee et Nanostructures (UMR CNRS 5586), Universite Claude Bernard Lyon 1, 69622 Villeurbanne Cedex (France)]. E-mail: ramos@lpmcn.univ-lyon1.fr

    2006-04-15

    Swift heavy ion irradiation is a powerful tool to tailor surfaces under controlled conditions at a nanometric scale. The growing importance of nanostructured surfaces for a wide variety of applications and fundamental investigations is now well established. In this paper I will mainly discuss the interest of such surfaces for investigations concerning solid-liquid interfaces. The role played by topographical defects on wetting properties of solid surfaces, and both the dissipative and the confinement effects on the interface will be demonstrated by simple examples.

  20. Corrosion performance of reinforced mortar in the presence of polymeric nano-aggregates: electrochemical behavior, surface analysis, and properties of the steel/cement paste interface

    NARCIS (Netherlands)

    Hu, J.; Koleva, D.A.; Van Breugel, K.

    2012-01-01

    This study reports on the effect of admixed polyethylene oxide-b-polystyrene (PEO113-b-PS70)micelles on corrosion behavior of reinforced mortar. The electrochemical measurement shows that the corrosion performance of the reinforcing steel was not significantly improved. However, surface analysis and

  1. Surface properties-vehicle interaction

    Science.gov (United States)

    Huft, D. L.; Her, I.; Agrawal, S. K.; Zimmer, R. A.; Bester, C. J.

    Several topics related to the surface properties of aircraft runways are discussed. The South Dakota profilometer; development of a data acquisition method for noncontact pavement macrotexture measurement; the traction of an aircraft tire on grooved and porous asphaltic concrete; holes in the pavements; the effect of pavement type and condition on the fuel consumption of vehicles; the traction loss of a suspended tire on a sinusoidal road; the effect of vehicle and driver characteristics on the psychological evaluation of road roughness; the correlation of subjective panel ratings of pavement ride quality with profilometer-derived measures of pavement roughness; a microprocessor-based noncontact distance measuring control system, and, the representation of pavement surface topography in predicting runoff depths and hydroplaning potential are discussed.

  2. Role of Steel Object Surface Condition on Behavior During Deformation

    Science.gov (United States)

    D'yachenko, S. S.; Ponomarenko, I. V.; Dub, S. N.

    2015-09-01

    Comparative analysis is provided for specimen mechanical properties of steels 18KhGT and 20Kh with tensile testing in relation to surface treatment: grinding, polishing, nitriding, carburizing, and ion-plasma treatment. It is shown that surface condition has a considerable effect on specimen behavior during deformation. It is established that the most favorable effect applies to ion bombardment with low-energy ions recommended as an effective method for improving component structural strength.

  3. Surface property modification of silicon

    Science.gov (United States)

    Danyluk, S.

    1984-01-01

    The main emphasis of this work has been to determine the wear rate of silicon in fluid environments and the parameters that influence wear. Three tests were carried out on single crystal Czochralski silicon wafers: circular and linear multiple-scratch tests in fluids by a pyramidal diamond simulated fixed-particle abrasion; microhardness and three-point bend tests were used to determine the hardness and fracture toughness of abraded silicon and the extent of damage induced by abrasion. The wear rate of (100) and (111) n and p-type single crystal Cz silicon abraded by a pyramidal diamond in ethanol, methanol, acetone and de-ionized water was determined by measuring the cross-sectional areas of grooves of the circular and linear multiple-scratch tests. The wear rate depends on the loads on the diamond and is highest for ethanol and lowest for de-ionized water. The surface morphology of the grooves showed lateral and median cracks as well as a plastically deformed region. The hardness and fracture toughness are critical parameters that influence the wear rate. Microhardness tests were conducted to determine the hardness as influenced by fluids. Median cracks and the damage zone surrounding the indentations were also related to the fluid properties.

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

    Science.gov (United States)

    Michalski; Saramago

    2000-07-15

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

  5. Sink property of metallic glass free surfaces.

    Science.gov (United States)

    Shao, Lin; Fu, Engang; Price, Lloyd; Chen, Di; Chen, Tianyi; Wang, Yongqiang; Xie, Guoqiang; Lucca, Don A

    2015-03-16

    When heated to a temperature close to glass transition temperature, metallic glasses (MGs) begin to crystallize. Under deformation or particle irradiation, crystallization occurs at even lower temperatures. Hence, phase instability represents an application limit for MGs. Here, we report that MG membranes of a few nanometers thickness exhibit properties different from their bulk MG counterparts. The study uses in situ transmission electron microscopy with concurrent heavy ion irradiation and annealing to observe crystallization behaviors of MGs. For relatively thick membranes, ion irradiations introduce excessive free volumes and thus induce nanocrystal formation at a temperature linearly decreasing with increasing ion fluences. For ultra-thin membranes, however, the critical temperature to initiate crystallization is about 100 K higher than the bulk glass transition temperature. Molecular dynamics simulations indicate that this effect is due to the sink property of the surfaces which can effectively remove excessive free volumes. These findings suggest that nanostructured MGs having a higher surface to volume ratio are expected to have higher crystallization resistance, which could pave new paths for materials applications in harsh environments requiring higher stabilities.

  6. Superoleophobic behavior induced by nanofeatures on oleophilic surfaces.

    Science.gov (United States)

    Ramos, Stella M M; Benyagoub, Abdenacer; Canut, Bruno; Jamois, Cécile

    2010-04-06

    The control of surface wetting properties to produce robust and strong hydrophobic and oleophobic effects on intrinsically oleophilic surfaces is at the heart of many technological applications. In this paper, we explore the conditions to observe such effects when the roughness of the substrate is of fractal nature and consists of nanofeatures obtained by the ion track etching technique. The wetting properties were investigated using eight different liquids with surface tensions gamma varying from 18 to 72 mN m(-1). While it is observed that all the tested oils readily wet the flat substrates, it is found that the contact angles are systematically exalted on the rough surfaces even for the liquids with very low surface tension. For liquids with gamma > or = 25 mN m(-1) an oleophobic behavior is clearly induced by the nanostructuration. For liquids with gamma < 25 mN m(-1), although the contact angle is enhanced on the nanorough surfaces, it conserves its oleophilic character (theta* lower than 90 degrees). Moreover, our experiments show that even in the case of hexane, liquid having the lowest surface tension, the homogeneous wetting (Wenzel state) is never reached. This high resistance to liquid impregnation is discussed within the framework of recent approaches explaining the wetting properties of superoleophobic surfaces.

  7. Wetting properties of molecularly rough surfaces

    Science.gov (United States)

    Svoboda, Martin; Malijevský, Alexandr; Lísal, Martin

    2015-09-01

    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.

  8. Differential surface properties of commercial crystalline telmisartan samples.

    Science.gov (United States)

    Laad, Preksha; Shete, Ganesh; Modi, Sameer R; Bansal, Arvind Kumar

    2013-05-13

    The aim of the present study was to investigate differences in surface chemistry of commercially available telmisartan (TMS) samples in Indian market and to correlate them to the surface molecular environment. Comprehensive characterization of material properties of four TMS samples from different sources showed that all samples exhibited same polymorphic form, but different particle shape, particle size distribution, surface energetics and surface chemistry. Wettability and surface free energy were determined using sessile drop contact angle technique. TMS samples exhibited significant variations in their wetting behavior. The role of crystal shape, particle size distribution, surface energetics and surface chemistry in controlling TMS powder wettability was collectively explored by contact angle experiments. Evaluation of work of adhesion (Wa), immersion (Wi) and spreading (Ws) indicated that samples had differential wetting behavior. The surface chemistry was elucidated by X-ray photoelectron spectroscopy (XPS). The surface polarity index was determined by XPS and expressed as (oxygen+nitrogen)-to-(carbon) atomic concentration ratio. It was found to be different for all four TMS samples. Crystal morphology of TMS polymorph A was predicted using Bravais-Friedel Donnay-Harker (BFDH) method. Molecular lipophilic surface potential (MLSP) data for TMS showed the varied surface lipophilic environment throughout the molecule. Hence it can be concluded that the differential abundance of surface elements play an important role in controlling the biopharmaceutical performance of TMS powder samples.

  9. Tunable surface properties from bioinspired polymers

    Science.gov (United States)

    van Zoelen, Wendy; Rosales, Adrianne; Murnen, Hannah; Zuckermann, Ronald; Segalman, Rachel

    2011-03-01

    Anti-fouling properties can be derived from patterned or ``ambiguous'' surfaces displaying multiple surface properties. Biological polymers with precisely controlled chain shapes and self-assembled structures are attractive materials for these applications, in which tunability is of great importance. We have investigated the surface properties of polypeptoids, a class of non-natural biomimetic polymers based on an N-substituted glycine backbone, that combine many of the advantageous properties of bulk polymers with those of synthetically produced proteins. Polypeptoids are of particular interest as they can be made in a sequence controlled fashion with functionalities already known to impart fouling-resistance (ethers, zwitterions, hydrophobicity, and nanoscale patterning). We demonstrate their surface stability and processibility from the standpoint of coating performance and also discuss controlled self-assembly of these materials. Used strategies include mediation of crystallization by incorporating chain defects and specific interactions.

  10. 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...

  11. Surface properties-vehicle interaction

    Energy Technology Data Exchange (ETDEWEB)

    Huft, D.L.; Her, I.; Agrawal, S.K.; Zimmer, R.A.; Bester, C.J.

    1984-01-01

    The 10 papers in the report deal with the following areas: South Dakota profilometer; development of a data-acquisition method for noncontact pavement macrotexture measurement; traction of an aircraft tire on grooved and porous asphaltic concrete; holes in the pavement-an assessment of their influence on safety; effect of pavement type and condition on the fuel consumption of vehicles; traction loss of a suspended tire on a sinusoidal road; effect of vehicle and driver characteristics on the psychological evaluation of road roughness; correlation of subjective panel ratings of pavement ride quality with profilometer-derived measures of pavement roughness; microprocessor-based noncontact distance measuring control system; and, representation of pavement-surface topography in predicting runoff depths and hydroplaning potential.

  12. The control mechanism of surface traps on surface charge behavior in alumina-filled epoxy composites

    Science.gov (United States)

    Li, Chuanyang; Hu, Jun; Lin, Chuanjie; He, Jinliang

    2016-11-01

    To investigate the role surface traps play in the charge injection and transfer behavior of alumina-filled epoxy composites, surface traps with different trap levels are introduced by different surface modification methods which include dielectric barrier discharges plasma, direct fluorination, and Cr2O3 coating. The resulting surface physicochemical characteristics of experimental samples were observed using atomic force microscopy, scanning electron microscopy and fourier transform infrared spectroscopy. The surface potential under dc voltage was detected and the trap level distribution was measured. The results suggest that the surface morphology of the experimental samples differs dramatically after treatment with different surface modification methods. Different surface trap distributions directly determine the charge injection and transfer property along the surface. Shallow traps with trap level of 1.03–1.11 eV and 1.06–1.13 eV introduced by plasma and fluorination modifications are conducive for charge transport along the insulating surface, and the surface potential can be modified, producing a smoother potential curve. The Cr2O3 coating can introduce a large number of deep traps with energy levels ranging from 1.09 to 1.15 eV. These can prevent charge injection through the reversed electric field formed by intensive trapped charges in the Cr2O3 coatings.

  13. Wetting behavior of lightly sulfonated polystyrene ionomers on silica surfaces.

    Science.gov (United States)

    Zhai, Xiaowen; Weiss, R A

    2008-11-18

    The wetting/dewetting behavior of thin films of lightly sulfonated low molecular weight polystyrene (SPS) ionomers spin-coated onto silica surfaces were studied using atomic force microscopy (AFM), contact angle measurements, and electron microscopy. The effects of the sulfonation level, the choice of the cation, the solvent used to spin-coat the films, and the molecular weight of the ionomer were investigated. Small angle X-ray scattering was used to determine the bulk microstructure of the films. The addition of the sulfonate groups suppressed the dewetting behavior of the PS above its glass transition temperature, e.g. no dewetting occurred even after 240 h of annealing at 120 degrees C. Increasing the sulfonation level led to more homogeneous and smoother surfaces. The choice of the cation used affected the wetting properties, but not in a predictable manner. When tetrahydrofuran (THF) or a THF/methanol mixed solvent was used for spin-casting, a submicron-textured surface morphology was produced, which may be a consequence of spinodal decomposition of the film surface during casting. Upon annealing for long times, the particles coalesced into a coherent, nonwetted film.

  14. Dispersion controlled by permeable surfaces: surface properties and scaling

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Bowen; Tartakovsky, Alexandre M.; Battiato, Ilenia

    2016-07-19

    Permeable and porous surfaces are common in natural and engineered systems. Flow and transport above such surfaces are significantly affected by the surface properties, e.g. matrix porosity and permeability. However, the relationship between such properties and macroscopic solute transport is largely unknown. In this work, we focus on mass transport in a two-dimensional channel with permeable porous walls under fully developed laminar flow conditions. By means of perturbation theory and asymptotic analysis, we derive the set of upscaled equations describing mass transport in the coupled channel–porous-matrix system and an analytical expression relating the dispersion coefficient with the properties of the surface, namely porosity and permeability. Our analysis shows that their impact on the dispersion coefficient strongly depends on the magnitude of the Péclet number, i.e. on the interplay between diffusive and advective mass transport. Additionally, we demonstrate different scaling behaviours of the dispersion coefficient for thin or thick porous matrices. Our analysis shows the possibility of controlling the dispersion coefficient, i.e. transverse mixing, by either active (i.e. changing the operating conditions) or passive mechanisms (i.e. controlling matrix effective properties) for a given Péclet number. By elucidating the impact of matrix porosity and permeability on solute transport, our upscaled model lays the foundation for the improved understanding, control and design of microporous coatings with targeted macroscopic transport features.

  15. Droplet impinging behavior on surfaces: Part II - Water on aluminium and cast iron surfaces

    Science.gov (United States)

    Sangavi, S.; Balaji, S.; Mithran, N.; Venkatesan, M.

    2016-09-01

    Droplet cooling of metal surfaces is an important area of research in industrial applications such as material quenching, nozzle spraying, etc. Fluids (water) act as an excellent agent in heat transfer to remove excess heat in various processes by convection and conduction. Such cooling process varies the material properties. The bubbles formed during droplet impinging on the surface act as heat sink and causes variation of height and spreading radius of the droplet with increase in temperature. In the present work, an experimental study of the droplet impinging behavior on Aluminium and Cast iron surfaces is reported. The water droplets are made to fall on the surface of the specimens from a specific height, which also influences the spreading radius. The effect of temperature on droplet height and droplet spreading radius is detailed.

  16. Surface effects on the mechanical properties of nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Xia Re [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China); Li Xide; Feng Xiqiao [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Qin Qinghua [School of Engineering, Australian National University, Canberra, ACT 0200 (Australia); Liu Jianlin, E-mail: fengxq@tsinghua.edu.cn [Department of Engineering Mechanics, China University of Petroleum, Qingdao 266555 (China)

    2011-07-01

    Using the theory of surface elasticity, we investigate the mechanical properties of nanoporous materials. The classical theory of porous materials is modified to account for surface effects, which become increasingly important as the characteristic sizes of microstructures shrink to nanometers. First, a refined Timoshenko beam model is presented to predict the effective elastic modulus of nanoporous materials. Then the surface effects on the elastic microstructural buckling behavior of nanoporous materials are examined. In particular, nanoporous gold is taken as an example to illustrate the application of the proposed model. The results reveal that both the elastic modulus and the critical buckling behavior of nanoporous materials exhibit a distinct dependence on the characteristic sizes of microstructures, e.g. the average ligament width.

  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. Physico-chemical surface properties of microalgae.

    Science.gov (United States)

    Ozkan, Altan; Berberoglu, Halil

    2013-12-01

    This study reports a comprehensive set of experimentally measured physico-chemical surface properties of 12 different microalgae including fresh and seawater species of green algae, diatoms and cyanobacteria. The surface free energy and its components including the acid-base (AB), van der Waals (LW), electron donor/acceptor parameters were quantified based on contact angle measurements along with the Lifshitz-van der Waals acid-base approach using the probe liquid surface tension parameters proposed by van Oss et al. as well as by Della Volpe and Siboni. Moreover, the zeta and surface potentials of all species were determined using electrophoretic mobility measurements along with using Smoluchowski's model. Finally, the free energy of cohesion of the microalgae was also determined based on the calculated surface energy properties. The results showed that the electron donor parameter correlated well with the free energy of cohesion in all groups of microalgae. Moreover, species known to form colonies and exhibit benthic cultures had distinctly hydrophobic surfaces compared to microalgae prefering planktonic growth. These results indicate the importance of surface hydrophobicity for causing biofouiling or flocculation of cultures. Finally, the zeta potentials did not show a distinctive trend with the types of microalgae but the surface potentials were markedly larger for the salt water species. The reported methods and data are expected to provide critical information for researchers and technology developers concerned with cell to cell and cell to substrata interactions of microalgae in algal biomass cultivation and harvesting, biofouling of membranes and surfaces, as well as cell-surface interactions in photosynthetic microbial fuel cell technologies.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kodali, Padma [Univ. of Maryland, College Park, MD (United States)

    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.

  20. Surface Properties of PEMFC Gas Diffusion Layers

    Energy Technology Data Exchange (ETDEWEB)

    WoodIII, David L [Los Alamos National Laboratory (LANL); Rulison, Christopher [Augustine Scientific; Borup, Rodney [Los Alamos National Laboratory (LANL)

    2010-01-01

    The wetting properties of PEMFC Gas Diffusion Layers (GDLs) were quantified by surface characterization measurements and modeling of material properties. Single-fiber contact-angle and surface energy (both Zisman and Owens-Wendt) data of a wide spectrum of GDL types is presented to delineate the effects of hydrophobic post-processing treatments. Modeling of the basic sessile-drop contact angle demonstrates that this value only gives a fraction of the total picture of interfacial wetting physics. Polar forces are shown to contribute 10-20 less than dispersive forces to the composite wetting of GDLs. Internal water contact angles obtained from Owens-Wendt analysis were measured at 13-19 higher than their single-fiber counterparts. An inverse relationship was found between internal contact angle and both Owens-Wendt surface energy and % polarity of the GDL. The most sophisticated PEMFC mathematical models use either experimentally measured capillary pressures or the standard Young-Laplace capillary-pressure equation. Based on the results of the Owens-Wendt analysis, an advancement to the Young-Laplace equation is proposed for use in these mathematical models, which utilizes only solid surface energies and fractional surface coverage of fluoropolymer. Capillary constants for the spectrum of analyzed GDLs are presented for the same purpose.

  1. Validation of a laboratory method for evaluating dynamic properties of reconstructed equine racetrack surfaces.

    Directory of Open Access Journals (Sweden)

    Jacob J Setterbo

    Full Text Available BACKGROUND: Racetrack surface is a risk factor for racehorse injuries and fatalities. Current research indicates that race surface mechanical properties may be influenced by material composition, moisture content, temperature, and maintenance. Race surface mechanical testing in a controlled laboratory setting would allow for objective evaluation of dynamic properties of surface and factors that affect surface behavior. OBJECTIVE: To develop a method for reconstruction of race surfaces in the laboratory and validate the method by comparison with racetrack measurements of dynamic surface properties. METHODS: Track-testing device (TTD impact tests were conducted to simulate equine hoof impact on dirt and synthetic race surfaces; tests were performed both in situ (racetrack and using laboratory reconstructions of harvested surface materials. Clegg Hammer in situ measurements were used to guide surface reconstruction in the laboratory. Dynamic surface properties were compared between in situ and laboratory settings. Relationships between racetrack TTD and Clegg Hammer measurements were analyzed using stepwise multiple linear regression. RESULTS: Most dynamic surface property setting differences (racetrack-laboratory were small relative to surface material type differences (dirt-synthetic. Clegg Hammer measurements were more strongly correlated with TTD measurements on the synthetic surface than the dirt surface. On the dirt surface, Clegg Hammer decelerations were negatively correlated with TTD forces. CONCLUSIONS: Laboratory reconstruction of racetrack surfaces guided by Clegg Hammer measurements yielded TTD impact measurements similar to in situ values. The negative correlation between TTD and Clegg Hammer measurements confirms the importance of instrument mass when drawing conclusions from testing results. Lighter impact devices may be less appropriate for assessing dynamic surface properties compared to testing equipment designed to simulate hoof

  2. 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.

  3. Study on tribological properties of multi-layer surface texture on Babbitt alloys surface

    Science.gov (United States)

    Zhang, Dongya; Zhao, Feifei; Li, Yan; Li, Pengyang; Zeng, Qunfeng; Dong, Guangneng

    2016-12-01

    To improve tribological properties of Babbitt alloys, multi-layer surface texture consisted of the main grooves and secondary micro-dimples are fabricated on the Babbitt substrate through laser pulse ablation. The tribological behaviors of multi-layer surface texture are investigated using a rotating type pin-on-disc tribo-meter under variation sliding speeds, and the film pressure distributions on the textured surfaces are simulated using computational fluid dynamics (CFD) method for elucidating the possible mechanisms. The results suggest that: (i) the multi-layer surface texture can reduce friction coefficient of Babbitt alloy, which has lowest friction coefficient of 0.03, in case of the groove parameter of 300 μm width and 15% of area density; (ii) the improvement effect may be more sensitive to the groove area density and the siding speed, and the textured surface with lower area density has lower friction coefficient under high sliding speed. Based on the reasons of (i) the secondary micro-dimples on Babbitt alloy possesses a hydrophobicity surface and (ii) the CFD analysis indicates that main grooves enhancing hydrodynamic effect, thus the multi-layer surface texture is regarded as dramatically improve the lubricating properties of the Babbitt alloy.

  4. 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.

  5. 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.

  6. Thermodynamic properties of water solvating biomolecular surfaces

    Science.gov (United States)

    Heyden, Matthias

    Changes in the potential energy and entropy of water molecules hydrating biomolecular interfaces play a significant role for biomolecular solubility and association. Free energy perturbation and thermodynamic integration methods allow calculations of free energy differences between two states from simulations. However, these methods are computationally demanding and do not provide insights into individual thermodynamic contributions, i.e. changes in the solvent energy or entropy. Here, we employ methods to spatially resolve distributions of hydration water thermodynamic properties in the vicinity of biomolecular surfaces. This allows direct insights into thermodynamic signatures of the hydration of hydrophobic and hydrophilic solvent accessible sites of proteins and small molecules and comparisons to ideal model surfaces. We correlate dynamic properties of hydration water molecules, i.e. translational and rotational mobility, to their thermodynamics. The latter can be used as a guide to extract thermodynamic information from experimental measurements of site-resolved water dynamics. Further, we study energy-entropy compensations of water at different hydration sites of biomolecular surfaces. This work is supported by the Cluster of Excellence RESOLV (EXC 1069) funded by the Deutsche Forschungsgemeinschaft.

  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

    Energy Technology Data Exchange (ETDEWEB)

    López-Oyama, A. B.; Silva-Molina, R. A.; Ruíz-García, J.; Guirado-López, R. A., E-mail: guirado@ifisica.uaslp.mx [Instituto de Física “Manuel Sandoval Vallarta,” Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, San Luis Potosí (Mexico); Gámez-Corrales, R. [Departamento de Física, Universidad de Sonora, Apartado Postal 5-088, 83190, Hermosillo, Sonora (Mexico)

    2014-11-07

    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. 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.

  10. 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...

  11. 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.

  12. 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.

  13. Curiosity's Autonomous Surface Safing Behavior Design

    Science.gov (United States)

    Neilson, Tracy A.; Manning, Robert M.

    2013-01-01

    The safing routines on all robotic deep-space vehicles are designed to put the vehicle in a power and thermally safe configuration, enabling communication with the mission operators on Earth. Achieving this goal is made a little more difficult on Curiosity because the power requirements for the core avionics and the telecommunication equipment exceed the capability of the single power source, the Multi-Mission Radioisotope Thermoelectric Generator. This drove the system design to create an operational mode, called "sleep mode", where the vehicle turns off most of the loads in order to charge the two Li-ion batteries. The system must keep the vehicle safe from over-heat and under-heat conditions, battery cell failures, under-voltage conditions, and clock failures, both while the computer is running and while the system is sleeping. The other goal of a safing routine is to communicate. On most spacecraft, this simply involves turning on the receiver and transmitter continuously. For Curiosity, Earth is above the horizon only a part of the day for direct communication to the Earth, and the orbiter overpass opportunities only occur a few times a day. The design must robustly place the Rover in a communicable condition at the correct time. This paper discusses Curiosity's autonomous safing behavior and describes how the vehicle remains power and thermally safe while sleeping, as well as a description of how the Rover communicates with the orbiters and Earth at specific times.

  14. Surface properties and exponential stress relaxations of mammalian meibum films.

    Science.gov (United States)

    Eftimov, Petar; Yokoi, Norihiko; Tonchev, Vesselin; Nencheva, Yana; Georgiev, Georgi As

    2017-03-01

    The surface properties of meibomian secretion (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The interfacial properties of canine, cMGS, and feline, fMGS, meibum films were studied using a Langmuir surface balance. These species were selected because they have blinking frequency and TF stability similar to those of humans. The sample's performance during dynamic area changes was evaluated by surface pressure (π)-area (A) isocycles and the layer structure was monitored with Brewster angle microscopy. The films' dilatational rheology was probed via the stress-relaxation technique. The animal MGS showed similar behavior both between each other and with human MGS (studied previously). They form reversible, non-collapsible, multilayer thick films. The relaxations of canine, feline, and human MGS films were well described by double exponential decay reflecting the presence of two processes: (1) fast elastic process, with characteristic time τ  100 s-emphasizing the meibum layers viscoelasticity. The temperature decrease from 35 to 25 °C resulted in decreased thickness and lateral expansion of all MGS layers accompanied with increase of the π/A hysteresis and of the elastic process contribution to π relaxation transients. Thus, MGS films of mammals with similar blinking frequency and TF stability have similar surface properties and stress relaxations unaltered by the interspecies MGS compositional variations. Such knowledge may impact the selection of animal mimics of human MGS and on a better understanding of lipid classes' impact on meibum functionality.

  15. 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.

  16. 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.

  17. Surfaces. [characterization of surface properties for predicting bond quality

    Science.gov (United States)

    Buckley, D. H.

    1983-01-01

    Techniques for the characterization of surface cleanliness and roughness for predicting the quality of an adhesive bond are outlined. Generally, smooth surfaces are only available from cleavage of crystalline materials along a natural cleavage plane. Films must be deposited on metal surfaces to achieve the same smoothness. Once the surfaces are clean, however, reaction with the ambient atmosphere becomes likely through diffusive and absorption processes, producing asperities. Electron diffraction, Auger electron, and X ray emission spectroscopy are used to characterize surface condition. Once the surface is observed to be clean, the application of an adhesive will usually prohibit separation along the adhesive; separation is then confined to the weaker of the two materials. Finally, the use of polytetrafluorothylene adhesive to test the adhesion between polymers and metal surfaces is described.

  18. Constraining the surface properties of effective Skyrme interactions

    Science.gov (United States)

    Jodon, R.; Bender, M.; Bennaceur, K.; Meyer, J.

    2016-08-01

    Background: Deformation energy surfaces map how the total binding energy of a nuclear system depends on the geometrical properties of intrinsic configurations, thereby providing a powerful tool to interpret nuclear spectroscopy and large-amplitude collective-motion phenomena such as fission. The global behavior of the deformation energy is known to be directly connected to the surface properties of the effective interaction used for its calculation. Purpose: The precise control of surface properties during the parameter adjustment of an effective interaction is key to obtain a reliable and predictive description of nuclear properties. The most relevant indicator is the surface-energy coefficient asurf. There are several possibilities for its definition and estimation, which are not fully equivalent and require a computational effort that can differ by orders of magnitude. The purpose of this study is threefold: first, to identify a scheme for the determination of asurf that offers the best compromise between robustness, precision, and numerical efficiency; second, to analyze the correlation between values for asurf and the characteristic energies of the fission barrier of 240Pu; and third, to lay out an efficient and robust procedure for how the deformation properties of the Skyrme energy density functional (EDF) can be constrained during the parameter fit. Methods: There are several frequently used possibilities to define and calculate the surface energy coefficient asurf of effective interactions built for the purpose of self-consistent mean-field calculations. The most direct access is provided by the model system of semi-infinite nuclear matter, but asurf can also be extracted from the systematics of binding energies of finite nuclei. Calculations can be carried out either self-consistently [Hartree-Fock (HF)], which incorporates quantal shell effects, or in one of the semiclassical extended Thomas-Fermi (ETF) or modified Thomas-Fermi (MTF) approximations. The

  19. 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.

  20. 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.

  1. 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.

  2. Correlation of average hydrophobicity, water/air interface surface rheological properties and foaming properties of proteins.

    Science.gov (United States)

    Medrano, A; Abirached, C; Araujo, A C; Panizzolo, L A; Moyna, P; Añón, M C

    2012-04-01

    A comparative study on the behavior in the air-water interface of β-lactoglobulin, α-lactoalbumin, glycinin and β-conglycinin was performed. The behavior at the interface was evaluated by equilibrium surface tension and surface rheological properties of adsorbed films. There were significant differences (α ≤ 0.05) in the values of the constants of adsorption to the interface of the four proteins. The glycinin had the slowest rate of adsorption, due to its low average hydrophobicity, low molecular flexibility and large molecular size. Smaller proteins like β-lactoglobulin and α-lactoalbumin tended to greater equilibrium pressure values than the larger proteins because of its higher rate of adsorption to the interface. The foam capacity of proteins showed a positive correlation with the average hydrophobicity; the maximal retained liquid volume or the initial rate of passage of liquid to foam were significantly lower (α ≤ 0.05) when protein was glycinin. The dilatational modulus of glycinin was the lowest, which implies lowest resistance to disruption of the film. Glycinin protein has lower proportion of gravitational drainage and higher disproportionation having perhaps a less resistant film. In conclusion, β-conglycinin and whey proteins showed a similar behavior, so β-conglycinin might be the best soybean protein to replace milk proteins in food formulations.

  3. The influence of fault geometry and frictional contact properties on slip surface behavior and off-fault damage: insights from quasi-static modeling of small strike-slip faults from the Sierra Nevada, CA

    Science.gov (United States)

    Ritz, E.; Pollard, D. D.

    2011-12-01

    Geological and geophysical investigations demonstrate that faults are geometrically complex structures, and that the nature and intensity of off-fault damage is spatially correlated with geometric irregularities of the slip surfaces. Geologic observations of exhumed meter-scale strike-slip faults in the Bear Creek drainage, central Sierra Nevada, CA, provide insight into the relationship between non-planar fault geometry and frictional slip at depth. We investigate natural fault geometries in an otherwise homogeneous and isotropic elastic material with a two-dimensional displacement discontinuity method (DDM). Although the DDM is a powerful tool, frictional contact problems are beyond the scope of the elementary implementation because it allows interpenetration of the crack surfaces. By incorporating a complementarity algorithm, we are able to enforce appropriate contact boundary conditions along the model faults and include variable friction and frictional strength. This tool allows us to model quasi-static slip on non-planar faults and the resulting deformation of the surrounding rock. Both field observations and numerical investigations indicate that sliding along geometrically discontinuous or irregular faults may lead to opening of the fault and the formation of new fractures, affecting permeability in the nearby rock mass and consequently impacting pore fluid pressure. Numerical simulations of natural fault geometries provide local stress fields that are correlated to the style and spatial distribution of off-fault damage. We also show how varying the friction and frictional strength along the model faults affects slip surface behavior and consequently influences the stress distributions in the adjacent material.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lollobrigida, V. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Basso, V.; Kuepferling, M.; Coïsson, M.; Olivetti, E. S.; Celegato, F. [Istituto Nazionale di Ricerca Metrologica (INRIM), I-10135 Torino (Italy); Borgatti, F. [CNR, Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), I-40129 Bologna (Italy); Torelli, P.; Panaccione, G. [CNR, Istituto Officina dei Materiali (IOM), Lab. TASC, I-34149 Trieste (Italy); Tortora, L. [Laboratorio di Analisi di Superficie, Dipartimento di Matematica e Fisica, Università Roma Tre, I-00146 Rome (Italy); Dipartimento di Ingegneria Meccanica, Università Tor Vergata, I-00133 Rome (Italy); Stefani, G.; Offi, F. [Dipartimento di Scienze, Università Roma Tre, I-00146 Rome (Italy)

    2014-05-28

    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.

  5. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-02-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle ( θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low- k to high- k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  6. Surface Modification of Textured Dielectrics and Their Wetting Behavior

    Science.gov (United States)

    Kumar, Vijay; Dhillon, Ajaypal Singh; Sharma, Niti Nipun

    2017-01-01

    Controlling the wettability on dielectric materials is a classical topic in surface engineering. Surface texturing and deposition of self-assembled monolayers (SAMs) are major approaches to achieve lower or higher water contact angle (θ c) and thereby making surface less or more wettable (more hydrophobic). Dielectric surfaces wetting has been engineered by surface modification and has been shown to achieve θ c to a maximum of 120° ± 5°. Further improvement in θ c to an extent greater than 150° ± 5° is desired to render the surface superhydrophobic. We report in this work an achievement of θ c > 150° ± 5° by combining the plasma-treated surface and octadecyltrichlorosilane (OTS) SAMs deposition on dielectrics, and this had been shown on dielectric ranging from low-k to high-k values. The improvement in wetting behavior and quality of dielectric surface with monolayer on plasma-treated surfaces are (is) investigated and characterized using atomic-force microscope (AFM), scanning electron microscope (SEM), contact angle goniometer, and Raman spectroscopy and x-ray photoelectron spectroscopy (XPS) and are compared with untreated dielectric surface with OTS monolayers.

  7. 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...

  8. Plastron properties of a superhydrophobic surface

    OpenAIRE

    2006-01-01

    Most insects and spiders drown when submerged during flooding or tidal inundation, but some are able to survive and others can remain submerged indefinitely without harm. Many achieve this by natural adaptations to their surface morphology to trap films of air, creating plastrons which fix the water-vapor interface and provide an incompressible oxygen-carbon dioxide exchange surface. Here the authors demonstrate how the surface of an extremely water-repellent foam mimics this mechanism of und...

  9. 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.

  10. Axially astigmatic surfaces: different types and their properties

    Science.gov (United States)

    Malacara-Doblado, Daniel; Malacara-Hernandez, Daniel; Garcia-Marquez, Jorge L.

    1996-12-01

    Axially astigmatic surfaces have different curvatures in orthogonal diameters. Toroidal and spherocylindrical optical surfaces are two mathematically different special cases of axially astigmatic surfaces as noted by Menchaca and Malacara (1986), but they are almost identical in the vicinity of the optical axis. The different between these two surfaces increases when the distance to the optical axis increases. We study the general properties of astigmatic surfaces and some special interesting cases.

  11. FRACTAL PROPERTIES OF ROCK FRACTURE SURFACES

    Institute of Scientific and Technical Information of China (English)

    王金安; 谢和平; MarekA.KWASNIEWSKI

    1996-01-01

    To give a better understanding of the morphological features of rock fracture surfaces within the framework of fractal geometry, the fractal characters of the rough surfaces in" rock are analyzed according to the variogram method. The study elaborates the significance of the geometric parameters-fractal dimension D and the intercept A on a log-log plot to the surface structure. Investigation extends to the anisotropy and heterogeneity of rock fracture surfaces, and the scale effect on the fractal estimation. The present study indicates that fractal dimension alone may not be sufficient to characterize the surface roughness of rock joints. A reliable estimation should take into account the combination of D and A.

  12. Effects of fractal surface on rheological behavior and combustion kinetics of modified brown coal water slurries

    Institute of Scientific and Technical Information of China (English)

    Zhifang Gao; Shuquan Zhu; Mingdong Zheng; Zhaojin Wu; Huihong Lu; Weiming Liu

    2015-01-01

    The paper reports the effects of surface fractal structures on the rheological behavior and combustion kinetics of raw brown coal and three modified coal water slurries (CWSs). The results show that the fractal structures and physicochemical properties of samples are dependent on various modification processes. The apparent viscosities of the coal water slurries increase with increasing surface fractal dimensions (D), especially with decreasing shear rates. Fur-thermore, it has been proved that the ignition temperatures and apparent activation energies of modified CWSs are lower than that of raw coal water slurry. Compared with the traditional qualitative analysis of the effect of pore structures on CWSs properties, D can more efficiently indicate the quantificational effect of pore structures on the rheological behavior and combustion kinetics of CWSs.

  13. Plastron properties of a superhydrophobic surface

    Science.gov (United States)

    Shirtcliffe, Neil J.; McHale, Glen; Newton, Michael I.; Perry, Carole C.; Pyatt, F. Brian

    2006-09-01

    Most insects and spiders drown when submerged during flooding or tidal inundation, but some are able to survive and others can remain submerged indefinitely without harm. Many achieve this by natural adaptations to their surface morphology to trap films of air, creating plastrons which fix the water-vapor interface and provide an incompressible oxygen-carbon dioxide exchange surface. Here the authors demonstrate how the surface of an extremely water-repellent foam mimics this mechanism of underwater respiration and allows direct extraction of oxygen from aerated water. The biomimetic principle demonstrated can be applied to a wide variety of man-made superhydrophobic materials.

  14. Surface structure and electronic properties of materials

    Science.gov (United States)

    Siekhaus, W. J.; Somorjai, G. A.

    1975-01-01

    A surface potential model is developed to explain dopant effects on chemical vapor deposition. Auger analysis of the interaction between allotropic forms of carbon and silicon films has shown Si-C formation for all forms by glassy carbon. LEED intensity measurements have been used to determine the mean square displacement of surface atoms of silicon single crystals, and electron loss spectroscopy has shown the effect of structure and impurities on surface states located within the band gap. A thin film of Al has been used to enhance film crystallinity at low temperature.

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

    Directory of Open Access Journals (Sweden)

    Hyun Hee Ahn

    2014-01-01

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

  16. Spectral properties and conformal type of surfaces

    Directory of Open Access Journals (Sweden)

    PHILIPPE CASTILLON

    2002-12-01

    Full Text Available In this short note, we announce a result relating the geometry of a riemannian surface to the positivity of some operators on this surface (the operators considered here are of the form surface Laplacian plus a scalar multiple of the curvature function. In particular we obtain a theorem "à la Huber'': under a spectral hypothesis we prove that the surface is conformally equivalent to a Riemann surface with a finite number of points removed. This problem has its origin in the study of stable minimal surfaces.Nesta comunicação, anunciamos um resultado que relaciona a geometria de uma superfície riemanniana com a positividade de certos operadores na superfície (os operadores considerados têm forma "Laplaciano mais um múltiplo da curvatura''. Em particular, obtemos um teorema "à la Huber'': usando uma condição espectral, provamos que a superfície é conformemente equivalente a uma superfície de Riemann menos um número finito de pontos. Este problema tem origem no estudo das superfícies mínimas estáveis.

  17. Psychometric Properties of the Brief Autism Mealtime Behaviors Inventory

    OpenAIRE

    2015-01-01

    The purpose of this study was to explore the psychometric properties of the Brief Autism Mealtime Behaviors Inventory (BAMBI). In a sample of 273 well-characterized children with ASD, we explored the factor structure of the BAMBI, determined the internal consistency of a newly derived factor structure and provide an empirically derived cut-off for the BAMBI total score. The new psychometrically identified structure consists of 4 factors: 1) Food Selectivity, 2) Disruptive Mealtime Behaviors, ...

  18. Surface properties of a single perfluoroalkyl group on water surfaces studied by surface potential measurements.

    Science.gov (United States)

    Shimoaka, Takafumi; Tanaka, Yuki; Shioya, Nobutaka; Morita, Kohei; Sonoyama, Masashi; Amii, Hideki; Takagi, Toshiyuki; Kanamori, Toshiyuki; Hasegawa, Takeshi

    2016-12-01

    A discriminative study of a single perfluoroalkyl (Rf) group from a bulk material is recently recognized to be necessary toward the total understanding of Rf compounds based on a primary chemical structure. The single molecule and the bulk matter have an interrelationship via an intrinsic two-dimensional (2D) aggregation property of an Rf group, which is theorized by the stratified dipole-arrays (SDA) theory. Since an Rf group has dipole moments along many C-F bonds, a single Rf group would possess a hydrophilic-like character on the surface. To reveal the hydration character of a single Rf group, in the present study, surface potential (ΔV) measurements are performed for Langmuir monolayers of Rf-containing compounds. From a comparative study with a monolayer of a normal hydrocarbon compound, the hydration/dehydration dynamics of a lying Rf group on water has first been monitored by ΔV measurements, through which a single Rf group has been revealed to have a unique "dipole-interactive" character, which enables the Rf group interacted with the water 'surface.' In addition, the SDA theory proves to be useful to predict the 2D aggregation property across the phase transition temperature of 19°C by use of the ΔV measurements.

  19. Effects of bio-functionalizing surface treatments on the mechanical behavior of open porous titanium biomaterials.

    Science.gov (United States)

    Amin Yavari, S; Ahmadi, S M; van der Stok, J; Wauthle, R; Riemslag, A C; Janssen, M; Schrooten, J; Weinans, H; Zadpoor, A A

    2014-08-01

    Bio-functionalizing surface treatments are often applied for improving the bioactivity of biomaterials that are based on otherwise bioinert titanium alloys. When applied on highly porous titanium alloy structures intended for orthopedic bone regeneration purposes, such surface treatments could significantly change the static and fatigue properties of these structures and, thus, affect the application of the biomaterial as bone substitute. Therefore, the interplay between biofunctionalizing surface treatments and mechanical behavior needs to be controlled. In this paper, we studied the effects of two bio-functionalizing surface treatments, namely alkali-acid heat treatment (AlAcH) and acid-alkali (AcAl), on the static and fatigue properties of three different highly porous titanium alloy implants manufactured using selective laser melting. It was found that AlAcH treatment results in minimal mass loss. The static and fatigue properties of AlAcH specimens were therefore not much different from as-manufactured (AsM) specimens. In contrast, AcAl resulted in substantial mass loss and also in significantly less static and fatigue properties particularly for porous structures with the highest porosity. The ratio of the static mechanical properties of AcAl specimens to that of AsM specimen was in the range of 1.5-6. The fatigue lives of AcAl specimens were much more severely affected by the applied surface treatments with fatigue lives up to 23 times smaller than that of AsM specimens particularly for the porous structures with the highest porosity. In conclusion, the fatigue properties of surface treated porous titanium are dependent not only on the type of applied surface treatment but also on the porosity of the biomaterial.

  20. Effect of calendering on paper surface properties

    Science.gov (United States)

    Vernhes, P.; Dubé, M.; Bloch, J.-F.

    2010-09-01

    Calendering of paper is an industrial finishing process designed to smoothen its surface so as to improve gloss as well as printability. In this article, we describe how calendering affects paper roughness on both microscopic and macroscopic length scales. We also discuss how these modifications relate to the morphology of the fibers composing the paper sheets. The characterization of the surface is carried out using an optical profilometer and two different species of fibers, as well as their mixture, are used. We first show that calendering induces modifications of the surface on all length scales measured and that these modifications are related by straightforward transformations. We also show that these results hold for papers formed from a mixture of fibers.

  1. Simulation and Experiment of Dynamic Properties of Joint Surfaces Based on Fractal Theory

    Directory of Open Access Journals (Sweden)

    Haitao Liu

    2015-01-01

    Full Text Available Dynamic properties of joint surfaces are researched, micro behavior is also analyzed and a mathematical model based on fractal theory is built, and the relationships between normal dynamic characteristics of joints and surface pressure, surface roughness, and real contact area were simulated. The contact pressure in joint, equivalent stiffness, and damping in joint were nonstrict proportional relationship, higher surface quality of the contact joint surface, can increase normal stiffness and reduce normal damping in joint. Experiments are arranged according to the theoretical model in order to analyze the share of every major factor that affects dynamic properties of joint surfaces. Two common materials HT200 and 2Cr13 under different processing methods, surface roughness, and surface areas are used, and law curves were built between the dynamic behavior of fixed joints and preload, processing method of contact surface, surface roughness; the correctness of the theory simulation results was confirmed. A spring-damping element joints finite model was built based on the pressure distribution contours. Based on the experimental data, we simulated the model of HT200 specimen by ANSYS, at the same time, compared our model, traditional model, and experimental result, and proved that the spring-damping distribution model based on pressure has a better simulative precision.

  2. Composition and physical properties of Enceladus' surface

    Science.gov (United States)

    Brown, R.H.; Clark, R.N.; Buratti, B.J.; Cruikshank, D.P.; Barnes, J.W.; Mastrapa, R.M.E.; Bauer, J.; Newman, S.; Momary, T.; Baines, K.H.; Bellucci, G.; Capaccioni, F.; Cerroni, P.; Combes, M.; Coradini, A.; Drossart, P.; Formisano, V.; Jaumann, R.; Langavin, Y.; Matson, D.L.; McCord, T.B.; Nelson, R.M.; Nicholson, P.D.; Sicardy, B.; Sotin, C.

    2006-01-01

    Observations of Saturn's satellite Enceladus using Cassini's Visual and Infrared Mapping Spectrometer instrument were obtained during three flybys of Enceladus in 2005. Enceladus' surface is composed mostly of nearly pure water ice except near its south pole, where there are light organics, CO2, and amorphous and crystalline water ice, particularly in the region dubbed the "tiger stripes." An upper limit of 5 precipitable nanometers is derived for CO in the atmospheric column above Enceladus, and 2% for NH 3 in global surface deposits. Upper limits of 140 kelvin (for a filled pixel) are derived for the temperatures in the tiger stripes.

  3. 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.

  4. 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.)

  5. Organosilane grafted silica: Quantitative correlation of microscopic surface characters and macroscopic surface properties

    Science.gov (United States)

    Ji, Tuo; Ma, Chi; Brisbin, Logan; Mu, Liwen; Robertson, Christopher G.; Dong, Yalin; Zhu, Jiahua

    2017-03-01

    In polymer composites, organosilanes are often used to modify the surface property of silica nanoparticles and improve the interfacial properties. Surface properties of the modified silica, such as grafting density and consequent surface energy, largely depend on the molecular structure of the silane. Achieving maximum interfacial bonding between the filler and polymer requires precise control of silica surface property. In this work, four silanes with similar molecular structure but different alkyl chain lengths, trimethoxy(propyl)silane, trimethoxy(octyl)silane, hexadecyltrimethoxysilane and trimethoxy(octadecyl)silane, are selected as model agents to study their roles in influencing silica surface property. The grafting density of silane on the silica is well controlled by regulating the reaction conditions. Three main surface characters, silane grafting density, surface energy and surface potential, are measured. More importantly, a linear relationship has been correlated when plotting grafting density vs. surface energy and grafting density vs. surface potential. Utilizing these relationships, a linear model has been developed to predict grafting density and surface energy by simply measuring surface potential. This model has been validated by both commercial silica and synthesized silica particles of different sizes.

  6. 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.

  7. Psychometric Properties of the Brief Autism Mealtime Behaviors Inventory

    Science.gov (United States)

    DeMand, Alexandra; Johnson, Cynthia; Foldes, Emily

    2015-01-01

    The purpose of this study was to explore the psychometric properties of the Brief Autism Mealtime Behaviors Inventory (BAMBI). In a sample of 273 well-characterized children with ASD, we explored the factor structure of the BAMBI, determined the internal consistency of a newly derived factor structure and provide an empirically derived cut-off for…

  8. Topographical and Functional Properties of Precursors to Severe Problem Behavior

    Science.gov (United States)

    Fahmie, Tara A.; Iwata, Brian A.

    2011-01-01

    A literature search identified 17 articles reporting data on 34 subjects who engaged in precursors to severe problem behavior, which we examined to identify topographical and functional characteristics. Unintelligible vocalization was the most common precursor to aggression (27%) and property destruction (29%), whereas self- or nondirected…

  9. Structure and surface properties of supported oxides

    Energy Technology Data Exchange (ETDEWEB)

    Leyrer, J.; Vielhaber, B.; Zaki, M.I.; Zhuang Shuxian; Weitkamp, J.; Knoezinger, H.

    1985-09-15

    Supported molybdate catalysts have been prepared on Al/sub 2/O/sub 3/,TiO/sub 2/, CeO/sub 2/, ZrO/sub 2/ and SiO/sub 2/ by impregnation from aqueous solution. The isoelectric point (IEPS) of the support surfaces determines the primary adsorption interaction of the molybdate species with the surface at a given pH. Raman spectroscopy shows monolayer formation on Al/sub 2/O/sub 3/, TiO/sub 2/ and CeO/sub 2/, while high proportions of MoO/sub 3/ are detected on SiO/sub 2/ and ZrO/sub 2/. Strong support effects influence the reducibility of the supported molybdate, which decreases in the sequence Mo/TiO/sub 2/ > Mo/ > CeO/sub 2/ > Mo/Al/sub 2/O/sub 3/ > Mo/ZrO/sub 2/. The dispersion of the monolayer on TiO/sub 2/, CeO/sub 2/ and Al/sub 2/O/sub 3/ seems to be fairly stable under reduction conditions, indicating strong chemical interaction with the supports.

  10. Peculiar surface behavior of some ionic liquids based on active pharmaceutical ingredients.

    Science.gov (United States)

    Restolho, José; Mata, José Luis; Saramago, Benilde

    2011-02-21

    The ionic liquids based on biologically active cations and anions, commonly designated by ionic liquids based on active pharmaceutical ingredients (ILs-APIs), are interesting compounds for use in pharmaceutical applications. Lidocaine docusate, ranitidine docusate, and didecyldimethylammonium ibuprofen are examples of promising ILs-APIs that were recently synthesized. They were submitted to biological testing and calorimetric measurements, but nothing is known about their surface properties. In this work, we measured the surface tension and the contact angles on both hydrophilic and hydrophobic surfaces in a temperature range as wide as possible. Based on the wettability data, the polarity fractions were estimated using the Fowkes theory. The peculiar surface behavior observed was tentatively attributed to the presence of mesophases.

  11. 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.

  12. 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.

  13. Anchoring properties of substrate with a grating surface

    Institute of Scientific and Technical Information of China (English)

    Ye Wen-Jiang; Xing Hong-Yu; Yang Guo-Chen

    2007-01-01

    The anchoring properties of substrate with a grating surface are investigated analytically. The alignment of nematic liquid crystal (NLC) in a grating surface originates from two mechanisms, thus the anchoring energy consists of two parts. One originates from the interaction potential between NLC molecules and the molecules on the substrate surface,and the other stems from the increased elastic strain energy. Based on the two mechanisms, the expression of anchoring energy per unit area of a projected plane of this grating surface is deduced and called the equivalent anchoring energy formula. Both the strength and the easy direction of equivalent anchoring energy are a function of the geometrical parameters (amplitude and pitch) of a grating surface. By using this formula, the grating surface can be replaced by its projected plane and its anchoring properties can be described by the equivalent anchoring energy formula.

  14. Neurocognitive derivation of protein surface property from protein aggregate parameters

    OpenAIRE

    Mishra, Hrishikesh; Lahiri, Tapobrata

    2011-01-01

    Current work targeted to predicate parametric relationship between aggregate and individual property of a protein. In this approach, we considered individual property of a protein as its Surface Roughness Index (SRI) which was shown to have potential to classify SCOP protein families. The bulk property was however considered as Intensity Level based Multi-fractal Dimension (ILMFD) of ordinary microscopic images of heat denatured protein aggregates which was known to have potential to serve as...

  15. Surface properties of solids and surface acoustic waves: Application to chemical sensors and layer characterization

    Science.gov (United States)

    Krylov, V. V.

    1995-09-01

    A general phenomenological approach is given for the description of mechanical surface properties of solids and their influence on surface acoustic wave propogation. Surface properties under consideration may be changes of the stress distribution in subsurface atomic layers, the presence of adsorbed gas molecules, surface degradation as a result of impacts from an aggressive environment, damage due to mechanical manufacturing or polishing, deposition of thin films or liquid layers, surface corrugations, etc. If the characteristic thickness of the affected layers is much less than the wavelengths of the propagating surface waves, then the effects of all these irregularities can be described by means of non-classical boundary conditions incorporating the integral surface parameters such as surface tension, surface moduli of elasticity and surface mass density. The effect of surface properties on the propagation of Rayleigh surface waves is analysed in comparison with the results of traditional approaches, in particular with Auld's energy perturbation method. One of the important implications of the above-mentioned boudnary conditions is that they are adequate for the description of the effect of rarely distributed adsorbed atoms or molecules. This allows, in particular, to obtain a rigorous theoretical description of chemical sensors using surface acoustic waves and to derive analytical expressions for their sensitivity.

  16. 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.

  17. 含氟丙烯酸酯共聚物结晶性与涂膜表面润湿性能研究%CORRELATION BETWEEN CRYSTALLIZATION BEHAVIOR OF FLUORINATED ACRYLATE COPOLYMERS AND THE SURFACE WETTING PROPERTY OF THEIR FILMS

    Institute of Scientific and Technical Information of China (English)

    陈慧琴; 周耿槟; 蔡智奇; 皮丕辉; 文秀芳; 郑大峰; 程江; 杨卓如

    2011-01-01

    以甲基丙烯酸2-全氟辛基乙酯( FOEMA)分别和不同烷烃链长丙烯酸酯(RA,CH2=CHCOOCnH2n+1,n=4,8,12,16,18)为单体,用自由基聚合法合成了一系列的含氟丙烯酸酯共聚物,通过X射线衍射(XRD)和示差扫描量热法(DSC)对共聚物进行了表征,发现结晶性与丙烯酸酯的烷烃链长度密切相关,当n=4,8,12时,在常温下不具有结晶性,当n=16,18时在常温下结晶,以碳氢侧链结晶为主.由DSC谱图测出了各共聚物的结晶焓.通过热力学计算,发现n=16时,恒压熵变值最小,说明该共聚物有序性最好.用多功能光电子能谱仪( XPS)测定了共聚物表面氟碳比(F/C)和官能团组成,并用接触角测试仪测定了与正十六烷和水的静态接触角.氟碳比随着烷烃侧链的增长而增大,从0.39增加到0.71.当n=16和18,表面非极性基团(-CF3和-CF2)明显增加,极性基团(-C=O和—C—O—C=O)明显减少导致了与正十六烷的静态接触角明显增大.结果表明共聚物中的碳氢侧链由于结晶导致全氟链段在成膜时更易于向涂膜-空气界面迁移,从而提高共聚合物表面疏水疏油性.%A series of fluorinated acrylate copolymers were synthesized via free radical copolymerization by using monomers of 2-(perflurooctyl)ethyl methacrylate (FOEMA) and n-alkyl acrylates (Ras) (n = 4, 8, 12, 16, 18) with various lengths of side chains. The crystalline behavior of the copolymers was characterized by X-ray diffraction (XRD) and differential scanning calorimetry ( DSC). It is found that the crystallization of acrylate copolymers is in close connection with the side-chain length of acrylates. The copolymers crystallized at room temperature when the side-chain length number n was 16 or 18, however, no crystallization was observed for the copolymers with n less than 16 under the same condition. The crystallization enthalpy changes of RA-co-FOEMA copolymers were determined from the DSC thermograms. The copolymer with n = 16 has the

  18. Statistical Properties of Fluctuations: A Method to Check Market Behavior

    CERN Document Server

    Panigrahi, Prasanta K; Manimaran, P; Ahalpara, Dilip P

    2009-01-01

    We analyze the Bombay stock exchange (BSE) price index over the period of last 12 years. Keeping in mind the large fluctuations in last few years, we carefully find out the transient, non-statistical and locally structured variations. For that purpose, we make use of Daubechies wavelet and characterize the fractal behavior of the returns using a recently developed wavelet based fluctuation analysis method. the returns show a fat-tail distribution as also weak non-statistical behavior. We have also carried out continuous wavelet as well as Fourier power spectral analysis to characterize the periodic nature and correlation properties of the time series.

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

    Directory of Open Access Journals (Sweden)

    Darija Domazet Jurašin

    2016-02-01

    Full Text Available 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.

  20. Effect of Surface Nanocrystallization on Fatigue Behavior of Pure Titanium

    Science.gov (United States)

    Wang, Qi; Sun, Qiaoyan; Xiao, Lin; Sun, Jun

    2016-01-01

    The high-cycle fatigue behavior was investigated in pure titanium after surface nanocrystallization (SNC Ti). Compared with the coarse-grained titanium (CG Ti) samples, the SNC Ti samples exhibit an improved fatigue life. The SNC has a remarkable influence on the fatigue cracks initiation and growth of pure titanium. The results show that, because the free-surface cracking is suppressed by the surface nanogradient structure in the SNC Ti, the fatigue cracks initiation sites change from the free surface to the subsurface. Meanwhile, the fatigue crack growth rate decreases due to the microstructural feature and residual compressive stress. The deformation twins in the subsurface of SNC Ti have a marked effect on the fatigue crack initiation and the crack growth. The former effect is due to the twin boundaries being preferential sites for crack initiation, while the latter is associated with the barriers that the twin boundaries pose to the propagation of dislocations. Furthermore, microstructural analysis indicates that the dislocation distribution in SNC Ti gradually becomes homogenous as fatigue processes. This homogeneous microstructure is also beneficial to the improvement of fatigue life.

  1. 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.

  2. Physicochemical properties and combustion behavior of duckweed during wet torrefaction.

    Science.gov (United States)

    Zhang, Shuping; Chen, Tao; Li, Wan; Dong, Qing; Xiong, Yuanquan

    2016-10-01

    Wet torrefaction of duckweed was carried out in the temperature range of 130-250°C to evaluate the effects on physicochemical properties and combustion behavior. The physicochemical properties of duckweed samples were investigated by ultimate analysis, proximate analysis, FTIR, XRD and SEM techniques. It was found that wet torrefaction improved the fuel characteristics of duckweed samples resulting from the increase in fixed carbon content, HHVs and the decrease in nitrogen and sulfur content and atomic ratios of O/C and H/C. It can be seen from the results of FTIR, XRD and SEM analyses that the dehydration, decarboxylation, solid-solid conversion, and condensation polymerization reactions were underwent during wet torrefaction. In addition, the results of thermogravimetric analysis (TGA) in air indicated that wet torrefaction resulted in significant changes on combustion behavior and combustion kinetics parameters. Duckweed samples after wet torrefaction behaved more char-like and gave better combustion characteristics than raw sample.

  3. Contact Angle Hysteresis on Graphene Surfaces and Hysteresis-free Behavior on Oil-infused Graphite Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Cyuan-Jhang; Li, Yueh-Feng [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Woon, Wei-Yen [Department of Physics, National Central University, Jhongli 320, Taiwan (China); Sheng, Yu-Jane, E-mail: yjsheng@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan (China); Tsao, Heng-Kwong, E-mail: hktsao@cc.ncu.edu.tw [Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan (China); Department of Physics, National Central University, Jhongli 320, Taiwan (China)

    2016-11-01

    Highlights: • Contact angle hysteresis(CAH) on four graphitic surfacesisinvestigated. • The hysteresis loopof water drops on the polished graphite sheetshowsparticularly small receding contact angle. • The significant CAH observed on CVD graphene and highly oriented pyrolytic graphite is attributed mainly to adhesion hysteresis. • An oil-infused surface of a graphite sheet is produced by imbibition of hexadecane into its porous structure. • The hysteresis-free property for water drops on such a surface is examined and quantitatively explained. - Abstract: Contact angle hysteresis (CAH) on graphitic surfaces, including chemical vapor deposition (CVD) graphene, reduced electrophoretic deposition (EPD) graphene, highly oriented pyrolytic graphite (HOPG), and polished graphite sheet, has been investigated. The hysteresis loops of water drops on the first three samples are similar but the receding contact angle is particularly small for the polished graphite sheet.The significant CAH observed on CVD graphene and HOPG associated with atom-scale roughness has to be attributed mainly to adhesion hysteresis (surface relaxation), instead of roughness or defects.The difference of the wetting behavior among those four graphitic samples has been further demonstrated by hexadecane drops. On the surface of HOPG or CVD graphene,the contact line expands continuously with time, indicating total wetting for which the contact angle does not exist and contact line pinning disappears. In contrast, on the surface of reduced EPD graphene, spontaneous spreading is halted by spikes on it and partial wetting with small contact angle (θ≈4°) is obtained. On the surface of polished graphite sheet, the superlipophilicity and porous structure are demonstrated by imbibition and capillary rise of hexadecane. Consequently, an oil-infused graphite surface can be fabricated and the ultralow CAH of water (∆θ≈2°) is achieved.

  4. Understanding the interfacial properties of nanostructured liquid crystalline materials for surface-specific delivery applications.

    Science.gov (United States)

    Dong, Yao-Da; Larson, Ian; Barnes, Timothy J; Prestidge, Clive A; Allen, Stephanie; Chen, Xinyong; Roberts, Clive J; Boyd, Ben J

    2012-09-18

    Nonlamellar liquid crystalline dispersions such as cubosomes and hexosomes have great potential as novel surface-targeted active delivery systems. In this study, the influence of internal nanostructure, chemical composition, and the presence of Pluronic F127 as a stabilizer, on the surface and interfacial properties of different liquid crystalline particles and surfaces, was investigated. The interfacial properties of the bulk liquid crystalline systems with coexisting excess water were dependent on the internal liquid crystalline nanostructure. In particular, the surfaces of the inverse cubic systems were more hydrophilic than that of the inverse hexagonal phase. The interaction between F127 and the bulk liquid crystalline systems depended on the internal liquid crystalline structure and chemical composition. For example, F127 adsorbed to the surface of the bulk phytantriol cubic phase, while for monoolein cubic phase, F127 was integrated into the liquid crystalline structure. Last, the interfacial adsorption behavior of the dispersed liquid crystalline particles also depended on both the internal nanostructure and the chemical composition, despite the dispersions all being stabilized using F127. The findings highlight the need to understand the specific surface characteristics and the nature of the interaction with colloidal stabilizer for understanding and optimizing the behavior of nonlamellar liquid crystalline systems in surface delivery applications.

  5. BIOPHYSICAL PROPERTIES OF NUCLEIC ACIDS AT SURFACES RELEVANT TO MICROARRAY PERFORMANCE.

    Science.gov (United States)

    Rao, Archana N; Grainger, David W

    2014-04-01

    Both clinical and analytical metrics produced by microarray-based assay technology have recognized problems in reproducibility, reliability and analytical sensitivity. These issues are often attributed to poor understanding and control of nucleic acid behaviors and properties at solid-liquid interfaces. Nucleic acid hybridization, central to DNA and RNA microarray formats, depends on the properties and behaviors of single strand (ss) nucleic acids (e.g., probe oligomeric DNA) bound to surfaces. ssDNA's persistence length, radius of gyration, electrostatics, conformations on different surfaces and under various assay conditions, its chain flexibility and curvature, charging effects in ionic solutions, and fluorescent labeling all influence its physical chemistry and hybridization under assay conditions. Nucleic acid (e.g., both RNA and DNA) target interactions with immobilized ssDNA strands are highly impacted by these biophysical states. Furthermore, the kinetics, thermodynamics, and enthalpic and entropic contributions to DNA hybridization reflect global probe/target structures and interaction dynamics. Here we review several biophysical issues relevant to oligomeric nucleic acid molecular behaviors at surfaces and their influences on duplex formation that influence microarray assay performance. Correlation of biophysical aspects of single and double-stranded nucleic acids with their complexes in bulk solution is common. Such analysis at surfaces is not commonly reported, despite its importance to microarray assays. We seek to provide further insight into nucleic acid-surface challenges facing microarray diagnostic formats that have hindered their clinical adoption and compromise their research quality and value as genomics tools.

  6. Applications of asymmetric nanotextured parylene surface using its wetting and transport properties

    Science.gov (United States)

    Sekeroglu, Koray

    In this thesis, basic digital fluidics devices were introduced using polymeric nanorods (nano-PPX) inspired from nature. Natural inspiration ignited this research by observing butterfly wings, water strider legs, rye grass leaves, and their asymmetric functions. Nano-PPX rods, manufactured by an oblique angle polymerization (OAP) method, are asymmetrically aligned structures that have unidirectional wetting properties. Nano-PPX demonstrates similar functions to the directional textured surfaces of animals and plants in terms of wetting, adhesion, and transport. The water pin-release mechanism on the asymmetric nano-PPX surface with adhesion function provides a great transport property. How the asymmetry causes transport is discussed in terms of hysteresis and interface contact of water droplets. In this study, the transport property of nano-PPX rods is used to guide droplets as well as transporting cargo such as microgels. With the addition of tracks on the nano-PPX rods, the surfaces were transformed into basic digital fluidics devices. The track-assisted nano-PPX has been employed to applications (i.e. sorting, mixing, and carrying cargo particles). Thus, digital fluidics devices fabricated on nano-PPX surface is a promising pathway to assemble microgels in the field of bioengineering. The characterization of the nano textured surface was completed using methods such as Scanning Electron Microscopy, Atomic Force Microscopy, Contact Angle Goniometry, and Fourier Transform Infra-Red Spectroscopy. These methods helped to understand the physical and chemical properties of nano-PPX. Parameters such as advancing and receding contact angles, nanorod tilt angle, and critical drop volumes were utilized to investigate the anisotropic wetting properties of nano-PPX surface. This investigation explained the directional wetting behavior of the surface as well as approaching new design parameters for adjusting surface properties. The nanorod tilt angle was a key parameter

  7. Surface and tribological behaviors of the bioinspired polydopamine thin films under dry and wet conditions.

    Science.gov (United States)

    Zhang, Wei; Yang, Fut K; Han, Yougun; Gaikwad, Ravi; Leonenko, Zoya; Zhao, Boxin

    2013-02-11

    Dopamine is a "sticky" biomolecule containing the typical functional groups of mussel adhesive proteins. It can self-polymerize into a nanoscale thin film on various surfaces. We investigated the surface, adhesion, friction, and cracking properties of polydopamine (PDA) thin films for their effective transfer to functional devices and biocompatible coatings. A series of surface characterizations and mechanical tests were performed to reveal the static and dynamic properties of PDA films coated on glass, polydimethylsiloxane (PDMS), and epoxy. We found that PDA films are highly hydrated under wet conditions because of their porous membrane-like nanostructures and hydrophilic functional groups. Upon dehydration, the films form cracks when they are coated on soft substrates due to internal stresses and the large mismatch in elastic modulus. The adhesive pull-off force or the effective work of adhesion increased with the contact time, suggesting dynamic interactions at the interface. A significant decrease in friction forces in water was observed on all three material surfaces coated with PDA; thus, the film might serve as a water-based lubrication coating. We attributed the different behavior of PDA films in air and in water to its hydration effects. These research findings provide insight into the stability, mechanical, and adhesive properties of the PDA films, which are critical for their applications.

  8. 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.

  9. 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.

  10. Modification of Textile Materials' Surface Properties Using Chemical Softener

    Directory of Open Access Journals (Sweden)

    Jurgita KOŽENIAUSKIENĖ

    2011-03-01

    Full Text Available In the present study the effect of technological treatment involving the processes of washing or washing and softening with chemical cationic softener "Surcase" produced in Great Britain on the surface properties of cellulosic textile materials manufactured from cotton, bamboo and viscose spun yarns was investigated. The changes in textile materials surface properties were evaluated using KTU-Griff-Tester device and FEI Quanta 200 FEG scanning electron microscope (SEM. It was observed that the worst hand properties and the higher surface roughness are observed of cotton materials if compared with those of bamboo and viscose materials. Also, it was shown that depending on the material structure the handle parameters of knitted materials are the better than the ones of woven fabrics.http://dx.doi.org/10.5755/j01.ms.17.1.249

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

    DEFF Research Database (Denmark)

    Genina, Natalja; Räikkönen, Heikki; Heinämäki, Jyrki

    2009-01-01

    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...... 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...... increment in particle size. The changes in thiamine powder flow were mainly due to narrowing in particle size distribution where the tendency for better flow of finer lactose was related to surface and size modifications. The aqueous mist application did not cause any alteration of the crystal structures...

  12. Mineralization behavior and interface properties of BG-PVA/bone composite implants in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Ma Yanxuan; Zheng Yudong; Huang Xiaoshan; Xi Tingfei; Han Dongfei [School of Materials Science and Engineering, Beijing University of Science and Technology, Beijing 100083 (China); Lin Xiaodan [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Song Wenhui, E-mail: zhengyudong@mater.ustb.edu.c, E-mail: wenhui.song@brunel.ac.u [Wolfson Center for Materials Processing, School of Engineering and Design, Brunel University, West London, UB8 3PH (United Kingdom)

    2010-04-15

    Due to the non-bioactivity and poor conjunction performance of present cartilage prostheses, the main work here is to develop the bioactive glass-polyvinyl alcohol hydrogel articular cartilage/bone (BG-PVA/bone) composite implants. The essential criterion for a biomaterial to bond with living bone is well-matched mechanical properties as well as biocompatibility and bioactivity. In vitro studies on the formation of a surface layer of carbonate hydroxyl apatite (HCA) and the corresponding variation of the properties of biomaterials are imperative for their clinical application. In this paper, the mineralization behavior and variation of the interface properties of BG-PVA/bone composites were studied in vitro by using simulated body fluid (SBF). The mineralization and HCA layer formed on the interface between the BG-PVA hydrogel and bone in SBF could provide the composites with bioactivity and firmer combination. The compression property, shear strength and interface morphology of BG-PVA/bone composite implants varying with the immersion time in SBF were characterized. Also, the influence laws of the immersion time, content of BG in the composites and aperture of bones to the mineralization behavior and interface properties were investigated. The good mineralization behavior and enhanced conjunction performance of BG-PVA/bone composites demonstrated that this kind of composite implant might be more appropriate cartilage replacements.

  13. 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.

  14. 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.

  15. Neurocognitive derivation of protein surface property from protein aggregate parameters

    Science.gov (United States)

    Mishra, Hrishikesh; Lahiri, Tapobrata

    2011-01-01

    Current work targeted to predicate parametric relationship between aggregate and individual property of a protein. In this approach, we considered individual property of a protein as its Surface Roughness Index (SRI) which was shown to have potential to classify SCOP protein families. The bulk property was however considered as Intensity Level based Multi-fractal Dimension (ILMFD) of ordinary microscopic images of heat denatured protein aggregates which was known to have potential to serve as protein marker. The protocol used multiple ILMFD inputs obtained for a protein to produce a set of mapped outputs as possible SRI candidates. The outputs were further clustered and largest cluster centre after normalization was found to be a close approximation of expected SRI that was calculated from known PDB structure. The outcome showed that faster derivation of individual protein’s surface property might be possible using its bulk form, heat denatured aggregates. PMID:21572883

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    E. Koyuncu

    2009-12-01

    Full Text Available 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, X-Ray diffraction and Vickers hardness.Findings: Two layers were determined by optic inspection on the samples that were called the compound and diffusion layers. Compound layer contain TiN and Ti2N nitrides, XRD results support in this formations. Maximum hardness was obtained at 10h treatment time and 1000°C treatment temperature. Micro hardness tests showed that hardness properties of the nitrided samples depend on treatment time and temperature.Practical implications: Titanium and its alloys have very attractive properties for many industries. But using of titanium and its alloys is of very low in mechanical engineering applications because of poor tribological properties.Originality/value: The nitriding of titanium alloy surfaces using plasma processes has already reached the industrial application stage in the biomedical field.

  18. Hydrophobic and electrostatic cell surface properties of Cryptosporidium parvum.

    OpenAIRE

    Drozd, C; Schwartzbrod, J

    1996-01-01

    Microbial adhesion to hydrocarbons and microelectrophoresis were investigated in order to characterize the surface properties of Cryptosporidium parvum. Oocysts exhibited low removal rates by octane (only 20% on average), suggesting that the Cryptosporidium sp. does not demonstrate marked hydrophobic properties. A zeta potential close to -25 mV at pH 6 to 6.5 in deionized water was observed for the parasite. Measurements of hydrophobicity and zeta potential were performed as a function of pH ...

  19. Properties of water surface discharge at different pulse repetition rates

    Energy Technology Data Exchange (ETDEWEB)

    Ruma,; Yoshihara, K. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Hosseini, S. H. R., E-mail: hosseini@kumamoto-u.ac.jp; Sakugawa, T.; Akiyama, H. [Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555 (Japan); Institute of Pulsed Power Science, Kumamoto University, Kumamoto 860-8555 (Japan); Akiyama, M. [Department of Electrical and Electronic Engineering, Kagoshima University, Kagoshima 890-0065 (Japan); Lukeš, P. [Institute of Plasma Physics, AS CR, Prague, Prague 18200 (Czech Republic)

    2014-09-28

    The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H₂O₂) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H₂O₂ and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.

  20. Evaporating behaviors of water droplet on superhydrophobic surface

    Science.gov (United States)

    Hao, PengFei; Lv, CunJing; He, Feng

    2012-12-01

    We investigated the dynamic evaporating behaviors of water droplet on superhydrophobic surfaces with micropillars. Our experimental data showed that receding contact angles of the water droplet increased with the decreasing of the scale of the micropillars during evaporation, even though the solid area fractions of the microstructured substrates remained constant. We also experimentally found that the critical contact diameters of the transition between the Cassie-Baxter and Wenzel states are affected not only by the geometrical parameters of the microstructures, but also by the initial volume of the water droplet. The measured critical pressure is consistent with the theoretical model, which validated the pressure-induced impalement mechanism for the wetting state transition.

  1. Positron studies of surfaces, structure and electronic properties of nanocrystals

    OpenAIRE

    Eijt, S. W. H.; Barbiellini, B.; Houtepen, A.J.; Vanmaekelbergh, D.; Mijnarends, P. E.; Bansil, A.

    2007-01-01

    A brief review is given of recent positron studies of metal and semiconductor nanocrystals. The prospects offered by positron annihilation as a sensitive method to access nanocrystal (NC) properties are described and compared with other experimental methods. The tunability of the electronic structure of nanocrystals underlies their great potential for application in many areas. Owing to their large surface-to-volume ratio, the surfaces and interfaces of NCs play a crucial role in determining ...

  2. Atomic arrangements and electronic properties of semiconductor surfaces and interfaces

    Science.gov (United States)

    Chadi, D. J.; Martin, R. M.

    1982-05-01

    The areas of research during the past 12 months have included: step-formation energies and domain orientation at Si(111) surfaces; the electronic structure of the Al-GaAs(110) surface chemisorption system; density-functional calculations of bulk properties of GaAs and of (100)GaAs-Ge interfaces; demonstration of the importance of correlation effects on the atomic and electronic structure of Si(111) surfaces; and derivation of an exact scaling law for the resistance of a thin wire for the one dimensional Anderson model containing Loth diagonal and off-diagonal disorder.

  3. 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.

  4. Properties of surface modes in one dimensional plasma photonic crystals

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, S.; Prasad, S., E-mail: prasad.surendra@gmail.com; Singh, V. [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India)

    2015-02-15

    Properties of surface modes supported at the interface of air and a semi-infinite one dimensional plasma photonic crystal are analyzed. The surface mode equation is obtained by using transfer matrix method and applying continuity conditions of electric fields and its derivatives at the interface. It is observed that with increase in the width of cap layer, frequencies of surface modes are shifted towards lower frequency side, whereas increase in tangential component of wave-vector increases the mode frequency and total energy carried by the surface modes. With increase in plasma frequency, surface modes are found to shift towards higher frequency side. The group velocity along interface is found to control by cap layer thickness.

  5. Effects of microorganisms on surface properties of chalcopyrite and bioleaching

    Institute of Scientific and Technical Information of China (English)

    CHEN Ming-lian; ZHANG Lin; GU Guo-hua; HU Yue-hua; SU Li-jun

    2008-01-01

    The alteration of surface properties of chalcopyrite after biological conditioning with Acidithiobacillus ferrooxidans and Acidithiobacillus caldus was evaluated by Zeta-potential,adsorption studies,FT-IR spectra and contact angle measurement.The Zeta-potential studies show that the iso-electric point(IEP) of chalcopyrite after bacterial treatment moves towards the IEP of pure cells,indicating the adsorption of cells on chalcopyrite surface.The FT-IR spectra of chalcopyrite treated with bacterial cells show the presence of the cell functional groups signifying cells adsorption.Due to the formation of elemental sulfur and intermediate copper sulphides on chalcopyrite surface,the contact angle and surface hydrophobicity of chalcopyrite increase at the initial bioleaching stage.Chalcopyrite bioleaching by Acidithiobacillus ferrooxidans has higher copper extraction,which agrees with the fact that Acidithiobacillus ferrooxidans adsorbed on chalcopyrite surface is much more than Acidithiobacillus caldus.The results support the direct mechanism of sulfide oxidations in bioleaching chalcopyrite.

  6. Thermodynamics and surface properties of liquid Al-Ga and Al-Ge alloys

    Energy Technology Data Exchange (ETDEWEB)

    Anusionwu, B.C. [Abdus Salam Int. Centre for Theoretical Physics, Trieste (Italy); Federal University of Technology, Department of Physics, Owerri (Nigeria); Adebayo, G.A. [Abdus Salam Int. Centre for Theoretical Physics, Trieste (Italy); University of Agriculture, Department of Physics, Abeokuta (Nigeria); Madu, C.A. [Federal University of Technology, Department of Physics, Owerri (Nigeria)

    2009-11-15

    The surface properties of Al-Ga and Al-Ge liquid alloys have been theoretically investigated at a temperature of 1100 K and 1220 K respectively. For the Al-Ga system, the quasi chemical model for regular alloy and a model for phase segregating alloy systems were applied, while for the Al-Ge system the quasi chemical model for regular and compound forming binary alloys were applied. In the case of Al-Ga, the models for the regular alloys and that for the phase segregating alloys produced the same value of order energy and same values of thermodynamic and surface properties, while for the Al-Ge system, the model for the regular alloy reproduced better the thermodynamic properties of the alloy. The model for the compound forming systems showed a qualitative trend with the measured values of the thermodynamic properties of the Al-Ge alloy and suggests the presence of a weak complex of the form Al{sub 2}Ge{sub 3}. The surface concentrations for the alloys show that Ga manifests some level of surface segregation in Al-Ga liquid alloy while the surface concentration of Ge in Al-Ge liquid alloy showed a near Roultian behavior below 0.8 atomic fraction of Ge. (orig.)

  7. Thermodynamics and surface properties of liquid Al-Ga and Al-Ge alloys

    Science.gov (United States)

    Anusionwu, B. C.; Adebayo, G. A.; Madu, C. A.

    2009-11-01

    The surface properties of Al-Ga and Al-Ge liquid alloys have been theoretically investigated at a temperature of 1100 K and 1220 K respectively. For the Al-Ga system, the quasi chemical model for regular alloy and a model for phase segregating alloy systems were applied, while for the Al-Ge system the quasi chemical model for regular and compound forming binary alloys were applied. In the case of Al-Ga, the models for the regular alloys and that for the phase segregating alloys produced the same value of order energy and same values of thermodynamic and surface properties, while for the Al-Ge system, the model for the regular alloy reproduced better the thermodynamic properties of the alloy. The model for the compound forming systems showed a qualitative trend with the measured values of the thermodynamic properties of the Al-Ge alloy and suggests the presence of a weak complex of the form Al2Ge3. The surface concentrations for the alloys show that Ga manifests some level of surface segregation in Al-Ga liquid alloy while the surface concentration of Ge in Al-Ge liquid alloy showed a near Roultian behavior below 0.8 atomic fraction of Ge.

  8. Hydrophobic and electrostatic cell surface properties of Cryptosporidium parvum.

    Science.gov (United States)

    Drozd, C; Schwartzbrod, J

    1996-04-01

    Microbial adhesion to hydrocarbons and microelectrophoresis were investigated in order to characterize the surface properties of Cryptosporidium parvum. Oocysts exhibited low removal rates by octane (only 20% on average), suggesting that the Cryptosporidium sp. does not demonstrate marked hydrophobic properties. A zeta potential close to -25 mV at pH 6 to 6.5 in deionized water was observed for the parasite. Measurements of hydrophobicity and zeta potential were performed as a function of pH and ionic strength or conductivity. Hydrophobicity maxima were observed at extreme pH values, with 40% of adhesion of oocysts to octane. It also appeared that ionic strength (estimated by conductivity) could influence the hydrophobic properties of oocysts. Cryptosporidium oocysts showed a pH-dependent surface charge, with zeta potentials becoming less negative as pH was reduced, starting at -35 mV for alkaline pH and reaching 0 at isoelectric points for pH 2.5. On the other hand, variation of surface charge with respect to conductivity of the suspension tested in this work was quite small. The knowledge of hydrophobic properties and surface charge of the parasite provides information useful in, for example, the choice of various flocculation treatments, membrane filters, and cleaning agents in connection with oocyst recovery.

  9. 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

    Energy Technology Data Exchange (ETDEWEB)

    Vojtech, D., E-mail: Dalibor.Vojtech@vscht.cz [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Voderova, M.; Kubasek, J.; Novak, P.; Seda, P.; Michalcova, A.; Fojt, J. [Department of Metals and Corrosion Engineering, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic); Hanus, J. [Department of Medical Biophysics, Charles University - Faculty of Medicine in Hradec Kralove, Simkova 870, 500 38 Hradec Kralove (Czech Republic); Mestek, O. [Department of Analytical Chemistry, Institute of Chemical Technology, Prague, Technicka 5, 166 28 Prague 6 (Czech Republic)

    2011-01-25

    Research highlights: {yields} Effect of short-time heat treatments on functional properties of a NiTi alloy. {yields} Negative effect of heat treatments on corrosion resistance. {yields} Positive effect of heat treatments on fatigue life. {yields} 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, HNO{sub 3} and H{sub 2}O, 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

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

    NARCIS (Netherlands)

    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

  11. 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.

  12. Membranes with Surface-Enhanced Antifouling Properties for Water Purification

    Science.gov (United States)

    Shahkaramipour, Nima; Tran, Thien N.; Ramanan, Sankara; Lin, Haiqing

    2017-01-01

    Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted. PMID:28273869

  13. Surface Chemistry and Properties of Oxides as Catalyst Supports

    Energy Technology Data Exchange (ETDEWEB)

    DeBusk, Melanie Moses [ORNL; Narula, Chaitanya Kumar [ORNL; Contescu, Cristian I [ORNL

    2015-01-01

    Heterogeneous catalysis relies on metal-oxides as supports for the catalysts. Catalyst supports are an indispensable component of most heterogeneous catalysts, but the role of the support is often minimized in light of the one played by the catalytically active species it supports. The active species of supported catalysts are located on the surface of the support where their contact with liquid or gas phase reactants will be greatest. Considering that support plays a major role in distribution and stability of active species, the absorption and retention of reactive species, and in some cases in catalytic reaction, the properties and chemistry that can occur at the surface of an oxide support are important for understanding their impact on the activity of a supported catalyst. This chapter examines this rich surface chemistry and properties of oxides used as catalyst supports, and explores the influence of their interaction with the active species.

  14. 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.

  15. Comparative first-principles study of clean-surface properties of metals

    Science.gov (United States)

    Patra, Abhirup; Sun, Jianwei; Perdew, John P.

    Metal surfaces are widely used in different applications from nano-devices to heterogeneous catalysis. Clean-surface properties such as the surface energy, work function and interlayer spacing importantly determine the behavior of metal surfaces. Prior work has been done to understand these properties using high-level methods including the local density approximation (LDA) and the generalized gradient approximation (PBE). In this work, we study (111) (100) and (110) surfaces of Pt, Pd, Cu, Al, Au, Ag, Rh and Ru by extrapolation from a finite number of layers. These surfaces are studied using SCAN, a new member of the computationally-efficient meta-GGA family of density functionals. We have compared the performance of SCAN and three other standard density functionals - LDA, PBE and PBEsol - to available experimental results. We find that the performance of the general-purpose SCAN is at the level of the more-specialized PBEsol, giving accurate metallic properties. Ref: Jianwei Sun, Adrienn Ruzsinszky, John P Perdew, Strongly Constrained and Appropriately Normed Semilocal Density Functional, Physical Review Letters115 (3), 036402 (2015). Supported by NSF under DMR-1305135, CNS-09-5884, and by DOE under DE-SC0012575, DE-AC02-05CH11231.

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

    Energy Technology Data Exchange (ETDEWEB)

    Harnisch, Jennifer Anne [Iowa State Univ., Ames, IA (United States)

    2001-01-01

    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.

  17. 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.

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

    DEFF Research Database (Denmark)

    Panpipat, Worawan; Xu, Xuebing; Guo, Zheng

    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 (CAL A) which showed a superior catalytic activity towards secondary alcohol to another lipases. Series of -sitosteryl fatty acid esters (C2-C18) were successfully prepared and their molecular structures were identified by 1HNMR and Fourier transform-infrared spectroscopy (FTIR). The thermal property...... 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 different...

  19. 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.

  20. On the identification of liquid surface properties using liquid bridges.

    Science.gov (United States)

    Kostoglou, M; Karapantsios, T D

    2015-08-01

    The term liquid bridge refers to the specific silhouette of a liquid volume when it is placed between two solid surfaces. Liquid bridges have been studied extensively both theoretically and experimentally during the last century due to their significance in many technological applications. It is worth noticing that even today new technological applications based on liquid bridges continue to appear. A liquid bridge has a well-defined surface configuration dictated by a rigid theoretical foundation so the potential of its utilization as a tool to study surface properties of liquids is apparent. However, it is very scarce in literature that the use of liquid bridges is suggested as an alternative to the well-established drop techniques (pendant/sessile drop). The present work (i) presents the theoretical background for setting up a liquid-bridge based surface property estimation problem, (ii) describes the required experimental equipment and procedures and (iii) performs a thorough literature review on the subject. A case with particular interest is that of liquid bridges made of electrically conducting liquids forming between two conducting solids; such a liquid bridge presents an integral electrical conductance value which is sensitive to the specific silhouette of the bridge. This enables the use of this integral conductance as shape descriptor instead of the conventional image processing techniques. Several attempts in literature for the estimation of liquid surface tension, liquid-solid contact angle and surfactant induced surface elasticity for conducting or non/conducting liquids are presented and the prospects of the technique are discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Pour-Ali, Sadegh, E-mail: pourali2020@ut.ac.ir; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-15

    Highlights: • Preparing mild steel surface with ultrafine grains by wire brushing process. • Performance of a smart coating on micro- and nano-crystalline surfaces. • Corrosion evaluation, surface analysis and ac/dc electrochemical measurements. • Ultrafine surface grains improve protective behavior of epoxy/PANI-CSA coating. - Abstract: 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.

  2. Examination of Poststroke Alteration in Motor Unit Firing Behavior Using High-Density Surface EMG Decomposition.

    Science.gov (United States)

    Li, Xiaoyan; Holobar, Ales; Gazzoni, Marco; Merletti, Roberto; Rymer, William Zev; Zhou, Ping

    2015-05-01

    Recent advances in high-density surface electromyogram (EMG) decomposition have made it a feasible task to discriminate single motor unit activity from surface EMG interference patterns, thus providing a noninvasive approach for examination of motor unit control properties. In the current study, we applied high-density surface EMG recording and decomposition techniques to assess motor unit firing behavior alterations poststroke. Surface EMG signals were collected using a 64-channel 2-D electrode array from the paretic and contralateral first dorsal interosseous (FDI) muscles of nine hemiparetic stroke subjects at different isometric discrete contraction levels between 2 to 10 N with a 2 N increment step. Motor unit firing rates were extracted through decomposition of the high-density surface EMG signals and compared between paretic and contralateral muscles. Across the nine tested subjects, paretic FDI muscles showed decreased motor unit firing rates compared with contralateral muscles at different contraction levels. Regression analysis indicated a linear relation between the mean motor unit firing rate and the muscle contraction level for both paretic and contralateral muscles (p < 0.001), with the former demonstrating a lower increment rate (0.32 pulses per second (pps)/N) compared with the latter (0.67 pps/N). The coefficient of variation (averaged over the contraction levels) of the motor unit firing rates for the paretic muscles (0.21 ± 0.012) was significantly higher than for the contralateral muscles (0.17 ± 0.014) (p < 0.05). This study provides direct evidence of motor unit firing behavior alterations poststroke using surface EMG, which can be an important factor contributing to hemiparetic muscle weakness.

  3. 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.

  4. Electric arc surfacing on low carbon steel: Structure and properties

    Science.gov (United States)

    Ivanov, Yurii; Gromov, Victor; Kormyshev, Vasilii; Konovalov, Sergey; Kapralov, Evgenii; Semin, Alexander

    2016-11-01

    By the methods of modern materials science, the structure-phase state and microhardness distribution along the cross-section of single and double coatings surfaced on martensite low carbon steel by alloy powder-cored wire were studied. It was established that the increased mechanical properties of surfaced layer are determined by the sub-micro and nanodispersed martensite structure formation, containing iron borides forming the eutectic of lamellar form. The plates of Fe2B are formed mainly in the eutectic of a single-surfaced layer, while FeB is formed in a double-surfaced layer. The existence of bend extinction contours indicating the internal stress fields formation at the boundaries of Fe borides-α-Fe phases were revealed.

  5. Optical properties of molecules chemisorbed on the Ni (111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Robota, H. J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Whitmore, P. M. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Harris, C. B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)

    1982-02-15

    The adsorption of a variety of molecules on Ni(111) is studied by UV/visible spectroscopic ellipsometry. The spectra were analyzed within a simple dielectric model. The absorption spectra of annealed, thin, condensed layers of pyrazine, pyridine, and naphthalene on the Ni(111) surface resemble bulk crystal spectra, indicating minimal perturbations due to the metal substrate. Chemisorption of molecules on the Ni(111) surface produced enhanced absorption between 2800Å and 3100Å. The wide range of adsorbate properties and surface chemistry suggest a modification of the optical response of the metal upon chemisorption. Furthermore, this enhanced optical absorption is attributed to nonvertical interband transitions made possible by loss of translational invariance at the surface.

  6. 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.

  7. 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.

  8. Surface adhesive properties of continuous PBO fiber after air-plasma-grafting-epoxy treatment

    Institute of Scientific and Technical Information of China (English)

    贾彩霞; 王乾; 陈平; 蒲永伟

    2016-01-01

    It was found that air dielectric barrier discharge (DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.

  9. 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.

  10. Surface modification by plasma polymerization: film deposition, tailoring of surface properties and biocompatibility

    OpenAIRE

    Os, van, J.

    2000-01-01

    The work described in this thesis concerns the surface modification of materials by thin film deposition in a plasma reactor. In particular, thin polymeric films bearing amine functionalities were synthesized by plasma polymerization of amino group containing monomers. In addition to the synthesis, attention was directed towards the characterization of these films, and the tailoring of their surface properties on a molecular level. Finally, the amino groups introduced by plasma polymerization...

  11. Microphase separated structure and surface properties of fluorinated polyurethane resin

    Energy Technology Data Exchange (ETDEWEB)

    Sudaryanto; Nishino, T.; Hori, Y.; Nakamae, K. [Dept. Chem. Sci. and Eng., Faculty of Engineering, Kobe University, Kobe (Japan)

    2000-10-01

    The effect of fluorination on microphase separation and surface properties of segmented polyurethane (PU) resin were investigated. A series of fluorinated polyurethane resin (FPU) was synthesized by reacting a fluorinated diol with aromatic diisocyanate. The microphase separated structure of FPU was studied by thermal analysis, and small angle X-ray scattering (SAXS) as well as wide angle X-ray diffraction (WAXD). The surface structure and properties were characterized by X-ray photoelectron spectroscopy (XPS) and dynamic contact angle measurement. The incorporation of fluorine into hard segment brings the FPU to have a higher hard domain cohesion and increase the phase separation, however localization of fluorine on the surface could not be observed. On the other hands, localization of fluorine on the surface could be achieved for soft segment fluorinated PU without any significant change in microphase separated structure. The result from this study give an important basic information for designing PU coating material with a low surface energy and strong adhesion as well as for development of release film on pressure sensitive adhesive tape. (author)

  12. 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.

  13. A simulation study on the thermal and wetting behavior of alkane thiol SAM on gold (111) surface

    Institute of Scientific and Technical Information of China (English)

    J. Meena Devi

    2014-01-01

    Molecular dynamics simulations have been performed to investigate the structural, thermal and wetting properties of self-assembled monolayer (SAM) of alkane thiol on gold surface. The specific heat capacity of the gold SAM surface was found to linearly increase with the temperature in the range 100-300 K. It was found to drop down at 400 K and this decrease might be attributed to the disorder of the SAM chains. Hydration of gold SAM surface for two different terminal groups, namely methyl (hydrophobic), and hydroxy (hydrophilic) was studied at room temperature. The difference in their wetting behavior and the structure of their interfacial water were examined from the estimation of the z density profile, radial distribution function, hydrogen bonds and orientation of water dipoles in the interfacial region. The present simulation results suggest that the wetting behavior of the gold SAM surface can be modified by altering the terminal functional group of the SAM chains.

  14. Enhancement of dynamic wetting properties by direct fabrication on robust micro-micro hierarchical polymer surfaces

    Science.gov (United States)

    Chu, Donghui; Nemoto, Akihiko; Ito, Hiroshi

    2014-05-01

    Understanding evaporation phenomena on hierarchical surfaces is of crucial importance for the design of robust superhydrophobic polymer structures for various applications. This fabrication method enables precise control of the dimensions to elucidate the dynamic wetting behavior affected by geometric parameters. That behavior exhibits three distinct evaporation modes: a constant contact line (CCL), a constant contact angle (CCA), and mixed mode during the droplet evaporation. The droplet evaporation results show that the sticky CCL mode and the Cassie-Wenzel transition can be prevented by engineering hierarchy integration. Moreover, the CCL-CCA transition point time scale exhibits remarkable dependence on surface dimensions such as the area fraction and solid-liquid contact line. Finally, the fabricated hierarchical structures indicate remarkable superhydrophobic properties, static contact angle above 160° and low sliding angle under 10°, with good durability in terms of aging effect and mechanical robustness for 2 months.

  15. Ion plated gold films: Properties, tribological behavior and performance

    Science.gov (United States)

    Spalvins, Talivaldis

    1987-01-01

    The glow discharge energizing favorably modifies and controls the coating/substrate adherence and the nucleation and growth sequence of ion plated gold films. As a result the adherence, coherence, internal stresses, and morphology of the films are significantly improved. Gold ion plated films because of their graded coating/substrate interface and fine uniform densely packed microstructure not only improve the tribological properties but also induce a surface strengthening effect which improves the mechanical properties such as yield, tensile, and fatigue strength. Consequently significant improvements in the tribological performance of ion plated gold films as compared to vapor deposited gold films are shown in terms of decreased friction/wear and prolonged endurance life.

  16. Surface properties of Ti-6Al-4V alloy part I: Surface roughness and apparent surface free energy.

    Science.gov (United States)

    Yan, Yingdi; Chibowski, Emil; Szcześ, Aleksandra

    2017-01-01

    Titanium (Ti) and its alloys are the most often used implants material in dental treatment and orthopedics. Topography and wettability of its surface play important role in film formation, protein adhesion, following osseointegration and even duration of inserted implant. In this paper, we prepared Ti-6Al-4V alloy samples using different smoothing and polishing materials as well the air plasma treatment, on which contact angles of water, formamide and diiodomethane were measured. Then the apparent surface free energy was calculated using four different approaches (CAH, LWAB, O-W and Neumann's Equation of State). From LWAB approach the components of surface free energy were obtained, which shed more light on the wetting properties of samples surface. The surface roughness of the prepared samples was investigated with the help of optical profilometer and AFM. It was interesting whether the surface roughness affects the apparent surface free energy. It was found that both polar interactions the electron donor parameter of the energy and the work of water adhesion increased with decreasing roughness of the surfaces. Moreover, short time plasma treatment (1min) caused decrease in the surface hydrophilic character, while longer time (10min) treatment caused significant increase in the polar interactions and the work of water adhesion. Although Ti-6Al-4V alloy has been investigated many times, to our knowledge, so far no paper has been published in which surface roughness and changes in the surface free energy of the alloy were compared in the quantitative way in such large extent. This novel approach deliver better knowledge about the surface properties of differently smoothed and polished samples which may be helpful to facilitate cell adhesion, proliferation and mineralization. Therefore the results obtained present also potentially practical meaning.

  17. 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.

  18. Surface properties of hydrogenated nanodiamonds: a chemical investigation.

    Science.gov (United States)

    Girard, H A; Petit, T; Perruchas, S; Gacoin, T; Gesset, C; Arnault, J C; Bergonzo, P

    2011-06-28

    Hydrogen terminations (C-H) confer to diamond layers specific surface properties such as a negative electron affinity and a superficial conductive layer, opening the way to specific functionalization routes. For example, efficient covalent bonding of diazonium salts or of alkene moieties can be performed on hydrogenated diamond thin films, owing to electronic exchanges at the interface. Here, we report on the chemical reactivity of fully hydrogenated High Pressure High Temperature (HPHT) nanodiamonds (H-NDs) towards such grafting, with respect to the reactivity of as-received NDs. Chemical characterizations such as FTIR, XPS analysis and Zeta potential measurements reveal a clear selectivity of such couplings on H-NDs, suggesting that C-H related surface properties remain dominant even on particles at the nanoscale. These results on hydrogenated NDs open up the route to a broad range of new functionalizations for innovative NDs applications development.

  19. Properties of laser alloyed surface layers on magnesium base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Galun, R.; Weisheit, A.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). Inst. fuer Werkstoffkunde und Werkstofftechnik)

    1998-01-01

    The investigations have shown that laser surface alloying is a promising process to improve the wear and corrosion properties of magnesium base alloys without affecting the initial bulk properties like the low density. With an alloying element combination of aluminium and nickel the wear rate in the scratch test was reduced by 90% compared to untreated pure magnesium. Additionally the corrosion resistance was improved by laser alloying with this element combination. Because of distortion or crack formation in the case of large area treatments, the laser alloying should be limited to the treatment of smaller areas. In the near future this process could be an interesting alternative to surface coating or to a partially reinforcement with ceramic fibres or particles. (orig.)

  20. 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.

  1. Electrokinetic Properties of TiO2 Nanotubular Surfaces

    Science.gov (United States)

    Lorenzetti, Martina; Gongadze, Ekaterina; Kulkarni, Mukta; Junkar, Ita; Iglič, Aleš

    2016-08-01

    Surface charge is one of the most significant properties for the characterisation of a biomaterial, being a key parameter in the interaction of the body implant with the surrounding living tissues. The present study concerns the systematic assessment of the surface charge of electrochemically anodized TiO2 nanotubular surfaces, proposed as coating material for Ti body implants. Biologically relevant electrolytes (NaCl, PBS, cell medium) were chosen to simulate the physiological conditions. The measurements were accomplished as titration curves at low electrolytic concentration (10-3 M) and as single points at fixed pH but at various electrolytic concentrations (up to 0.1 M). The results showed that all the surfaces were negatively charged at physiological pH. However, the zeta potential values were dependent on the electrolytic conditions (electrolyte ion concentration, multivalence of the electrolyte ions, etc.) and on the surface characteristics (nanotubes top diameter, average porosity, exposed surface area, wettability, affinity to specific ions, etc.). Accordingly, various explanations were proposed to support the different experimental data among the surfaces. Theoretical model of electric double layer which takes into account the asymmetric finite size of ions in electrolyte and orientational ordering of water dipoles was modified according to our specific system in order to interpret the experimental data. Experimental results were in agreement with the theoretical predictions. Overall, our results contribute to enrich the state-of-art on the characterisation of nanostructured implant surfaces at the bio-interface, especially in case of topographically porous and rough surfaces.

  2. 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.

  3. Surface interactions and fouling properties of Micrococcus luteus with microfiltration membranes.

    Science.gov (United States)

    Feng, Lei; Li, Xiufen; Song, Ping; Du, Guocheng; Chen, Jian

    2011-11-01

    This study was conducted to investigate microbial adhesion of Micrococcus luteus to polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes in relation to the variation of the interfacial energies in the membrane-bacteria systems, for revealing effects of short-range surface interactions on filtration behavior. Both the membranes and M. luteus showed typical strong electron donors and hydrophilic properties. The AB component was dominant in the interfacial energies of the two membrane-bacteria systems. M. luteus presented larger negative U(mlb)(XDLVO) to the PP membrane than to the PVDF membrane. The adhesion experiments also proved that M. luteus had higher adhesion percentage to the PP membrane. This study demonstrated that the adhesion potentials of M. luteus to the PP and PVDF membranes might be explained in terms of bacterium, membrane, and intervening medium surface properties, which are mainly determined by the interfacial energies in the systems according to the XDLVO theory.

  4. Synthesis and surface properties of polyurethane modified by polysiloxane

    Institute of Scientific and Technical Information of China (English)

    Linlin FENG; Xingyuan ZHANG; Jiabing DAI; Zhen GE; Jing CHAO; Chenyan BAI

    2008-01-01

    A series of polyurethanes modified by polysiloxane (Si-PU) were synthesized based on 2,4-toluene diisocyanate (TDI), dihydroxybutyl-terminated polydimethylsiloxane (DHPDMS), polytetramethylene glycol (PTMG) and 1,4-butanediol (BDO). Fourier transform infrared spectroscopy analysis showed that DHPDMS had been incorporated into the polyurethane chains. With the increase of DHPDMS content, the water contact angle increased while the surface tension decreased. As the DHPDMS content increases above 5%, both the contact angle and the surface tension tend to approach a constant. The contact angle increases with increasing temperature, and it tends to approach a constant when the temperature is higher than 50℃. The result indicates that Si-PU exhibits good surface and mechanical properties when the DHPDMS content is 5%.

  5. PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

    Institute of Scientific and Technical Information of China (English)

    Tai-jiang Gui; Hao Wei; Ying Zhao; Xiu-lin Wang; Du-jin Wang; Duan-fu Xu

    2006-01-01

    A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray (EDAX) show that the length and content ofperfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.

  6. 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.

  7. 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.

  8. A Theoretical Analysis of Potential Extinction Properties of Behavior-Specific Manual Restraint

    Science.gov (United States)

    Cipani, Ennio; Thomas, Melvin; Martin, Daniel

    2007-01-01

    This paper will examine possible extinction properties of behavior-specific manual restraint. It will analyze the possibility of extinction being produced via restraint with respect to the target behavior's possible environmental functions. The theoretical analysis will involve the analysis of behavioral properties of restraint during two temporal…

  9. 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

  10. Modeling of surface roughness: application to physical properties of paper

    Science.gov (United States)

    Bloch, Jean-Francis; Butel, Marc

    2000-09-01

    Papermaking process consists in a succession of unit operations having for main objective the expression of water out of the wet paper pad. The three main stages are successively, the forming section, the press section and finally the drying section. Furthermore, another operation (calendering) may be used to improve the surface smoothness. Forming, pressing and drying are not on the scope of this paper, but the influence of formation and calendering on surface roughness is analyzed. The main objective is to characterize the materials and specially its superficial structure. The proposed model is described in order to analyze this topographical aspect. Some experimental results are presented in order to illustrate the interest of this method to better understand physical properties. This work is therefore dedicated to the description of the proposed model: the studied surface is measured at a microscopic scale using for example, a classical stylus profilometry method. Then the obtained surface is transformed using a conformal mapping that retains the surface orientations. Due to the anisotropy of the fiber distribution in the plane of the sheet, the resulting surface is often not isotropic. Hence, the micro facets that identify the interfaces between pores and solid (fibers in the studied case) at the micro level are transformed into a macroscopic equivalent structure. Furthermore, an ellipsoid may be fit to the experimental data in order to obtain a simple model. The ellipticities are proved to be linked for paper to both fiber orientation (through other optical methods) and roughness. These parameters (ellipticities) are shown to be very significant for different end-use properties. Indeed, they shown to be correlated to printing or optical properties, such as gloss for example. We present in a first part the method to obtain a macroscopic description from physical microscopic measurements. Then measurements carried on different paper samples, using a classical

  11. The influence of surface reflectance anisotropy on estimation of soil properties

    Science.gov (United States)

    Bartholomeus, Harm; Roosjen, Peter; Clevers, Jan

    2014-05-01

    The spatial variation in soil properties is an important factor for agricultural management. Unmanned airborne vehicles (UAV's) equipped with a hyperspectral mapping system may provide these data, but anisotropic reflectance effects may have an influence on the derived soil properties. Besides influencing the reflectance, angular observations may deliver added information about soil properties. We investigated the anisotropic behavior of 59 soil samples with a large variation in soil composition, by measuring their reflectance (350-2500 nm) over 92 different angles using a robot-based laboratory goniometer system. The results show that the anisotropic behavior of the soils influences the measured reflectance significantly, which limits the accurate prediction of soil properties (OM and clay especially). However, prediction accuracies of OM increase when spectra are measured under specific angles. Prediction accuracies further increase when a combination of observation angles is being used. Apart from that, using UAV's the wavelength range is limited to about 1000 nm. In general, this will decrease the model performance, but our results show that this effect can largely be compensated by combining multiple observation angles. Altogether, we demonstrate that surface anisotropy influences the prediction of soil properties negatively. This effect can be reduced by combining spectra acquired under different angles. Moreover, predictions can be improved if combinations of different observation angles are used.

  12. Chondrocyte behavior on nanostructured micropillar polypropylene and polystyrene surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Prittinen, Juha [Department of Applied Physics, University of Eastern Finland, Kuopio (Finland); Jiang, Yu [Department of Chemistry, University of Eastern Finland, Joensuu (Finland); Ylärinne, Janne H. [Department of Applied Physics, University of Eastern Finland, Kuopio (Finland); Pakkanen, Tapani A. [Department of Chemistry, University of Eastern Finland, Joensuu (Finland); Lammi, Mikko J., E-mail: mikko.lammi@uef.fi [Department of Applied Physics, University of Eastern Finland, Kuopio (Finland); Qu, Chengjuan [Department of Applied Physics, University of Eastern Finland, Kuopio (Finland)

    2014-10-01

    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 α{sub 1}(II), procollagen α{sub 1}(X), and procollagen α{sub 2}(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 α{sub 1}(II) appeared to decrease in passaged chondrocytes. However, the expressions of procollagen α{sub 2}(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

  13. Modulating semiconductor surface electronic properties by inorganic peptide-binders sequence design.

    Science.gov (United States)

    Matmor, Maayan; Ashkenasy, Nurit

    2012-12-19

    The use of proteins and peptides as part of biosensors and electronic devices has been the focus of intense research in recent years. However, despite the fact that the interface between the bioorganic molecules and the inorganic matter plays a significant role in determining the properties of such devices, information on the electronic properties of such interfaces is sparse. In this work, we demonstrate that the identity and position of single amino acid in short inorganic binding protein-segments can significantly modulate the electronic properties of semiconductor surfaces on which they are bound. Specifically, we show that the introduction of tyrosine or tryptophan, both possessing an aromatic side chain which higher occupied molecular orbitals are positioned in proximity to the edge of GaAs valence band, to the sequence of a peptide that binds to GaAs (100) results in changes of both the electron affinity and surface potential of the semiconductor. These effects were found to be more pronounced than the effects induced by the same amino acids once bound on the surface in a head-tail configuration. Furthermore, the relative magnitude of each effect was found to depend on the position of the modification in the sequence. This sequence dependent behavior is induced both indirectly by changes in the peptide surface coverage, and directly, probably, due to changes in the orientation and proximity of the tyrosine/tryptophan side group with respect to the surface due to the preferred conformation the peptide adopts on the surface. These studies reveal that despite the use of short protein oligomers and aiming at a non-natural-electronic task, the well-known relations between the proteins' structure and function is preserved. Combining the ability to tune the electronic properties at the interface with the ability to direct the growth of inorganic materials makes peptides promising building blocks for the construction of novel hybrid electronic devices and biosensors.

  14. Membrane fouling in a submerged membrane bioreactor with focus on surface properties and interactions of cake sludge and bulk sludge.

    Science.gov (United States)

    Yu, Haiying; Lin, Hongjun; Zhang, Meijia; Hong, Huachang; He, Yiming; Wang, Fangyuan; Zhao, Leihong

    2014-10-01

    In this study, the fouling behaviors and surface properties of cake sludge and bulk sludge in a submerged membrane bioreactor (MBR) were investigated and compared. It was found that the specific filtration resistance (SFR) of cake sludge was about 5 times higher than that of bulk sludge. Two types of sludge possessed similar extracellular polymeric substances (EPS) content, particle size distribution (PSD) and zeta potential. However, their surface properties in terms of surface tensions were significantly different. Further analysis showed that cake sludge was more hydrophilic and had worse aggregation ability. Moreover, cake sludge surface possessed more hydrocarbon, less oxygen and nitrogen moieties than bulk sludge surface. It was suggested that, rather than EPS and PSD differences, the differences in the surface composition were the main cause of the great differences in SFR and adhesion ability between cake sludge and bulk sludge.

  15. The vibrational and buckling behaviors of piezoelectric nanobeams with surface effects

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Z; Jiang, L Y, E-mail: lyjiang@eng.uwo.ca [Department of Mechanical and Materials Engineering, University of Western Ontario, London, ON, N6A 5B9 (Canada)

    2011-06-17

    In this work, the influence of surface effects, including residual surface stress, surface elasticity and surface piezoelectricity, on the vibrational and buckling behaviors of piezoelectric nanobeams is investigated by using the Euler-Bernoulli beam theory. The surface effects are incorporated by applying the surface piezoelectricity model and the generalized Young-Laplace equations. The results demonstrate that surface effects play a significant role in predicting these behaviors. It is found that the influence of the residual surface stress and the surface piezoelectricity on the resonant frequencies and the critical electric potential for buckling is more prominent than the surface elasticity. The nanobeam boundary conditions are also found to influence the surface effects on these parameters. This study also shows that the resonant frequencies can be tuned by adjusting the applied electrical load. The present study is envisaged to provide useful insights for the design and applications of piezoelectric-beam-based nanodevices.

  16. Contribution of polarimetric imaging for the characterization of fibrous surface properties at different scales

    Science.gov (United States)

    Tourlonias, Michel; Bigué, Laurent; Bueno, Marie-Ange

    2010-01-01

    The point in using polarimetric imaging for surface characterization is highlighted in this paper. A method for the evaluation of nonwoven surface properties at microscopic and macroscopic scales is described. This method is based on a polarimetric apparatus and various image processing operations are then performed depending on the studied scale. Polarimetric imaging applied to nonwovens, particularly degree of polarization imaging, highlights texture inhomogeneities. At both scales, image processing techniques were designed to analyze surface zones of different textures. At the macroscopic scale, a basic image processing was developed in order to detect the nonwoven manufacturing process defects. Moreover at the microscopic scale, i.e. at the fiber scale, image processing was adapted to evaluate fiber orientation within nonwovens, which is known to be an important information for mechanical behavior prediction.

  17. New insight into surface properties of LB film of an amphiphilic terpolymer

    Institute of Scientific and Technical Information of China (English)

    Xiu Li Yue; Fang Ma; Zhi Fei Dai; Meng Liu; Lei Xing; Hai Yan Fan; Zhan Wen Xing; Shao Qin Liu

    2011-01-01

    Amphiphilic terpolymer (TPR) exhibits good film-forming behavior on pure water observed by means of n-A isotherms. To gain insight into physical properties of TPR, the films have been deposited on silicon substrates at different surface pressure by Langmuir-Blodgett (LB) technique. It was found that the increase in peak intensities of stretching mode was due to orderly packing of the films. The contact angles increased with increasing surface pressure, indicating an increase in hydrophobicity due to dense packing of chains of TPR. The cyclic voltammetric measurements indicated that TPR showed good current shielding effect for electron-transfer. In a word, LB films of TPR can produce a variety of structures with varied topography, enabling us to control not only the functionality of the surface, but also the interfacial transport characteristics.

  18. 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.

  19. 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.

  20. Aggregation Operators Review - Mathematical Properties and Behavioral Measures

    Directory of Open Access Journals (Sweden)

    David L. La Red Martínez

    2016-09-01

    Full Text Available A problem that humans must face very often is that of having to add, melt or synthesize information, that is, combine together a series of data from various sources to reach a certain conclusion or make a certain decision. This involves the use of one or more aggregation operators capable to provide a collective preference relation. These operators must be chosen according to specific criteria taking into account the characteristic properties of each operator. Some conditions to be taken into account to identify them are the following: axiomatic strength, empirical setting, adaptability, numerical efficiency, compensation and compensation range, added behavior and scale level required of the membership functions. It is possible to establish a general list of possible mathematical properties whose verification might be desirable in certain cases: boundary conditions, continuity, not decreasing monotony, symmetry, idempotence, associativity, bisymmetry, self-distributivity, compensation, homogeneity, translativity, stability, ϕ-comparability, sensitivity and locally internal functions. For analyze the attitudinal character of the aggregation operator the following measures are studied: disjunction degree (orness, dispersion, balance and divergence. In this paper, a review of these issues is presented.

  1. 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.

  2. Surface functional groups and redox property of modified activated carbons

    Institute of Scientific and Technical Information of China (English)

    Zhang Xianglan; Deng Shengfu; Liu Qiong; Zhang Yan; Cheng Lei

    2011-01-01

    A series of activated carbons (ACs) were prepared using HNO3, H2O2 and steam as activation agents with the aim to introduce functional groups to carbon surface in the ACs preparation process. The effects of concentration of activation agent, activation time on the surface functional groups and redox property of ACs were characterized by Temperature Program Desorption (TPD) and Cyclic Voitammetry (CV). Results showed that lactone groups of ACs activated by HNO3 increase with activation time, and the carboxyl groups increase with the concentration of HNO3. Carbonyl/quinine groups of ACs activated by H2O2 increase with the activation time and the concentration of H2O2, although the acidic groups decrease with the concentration of H2O2. The redox property reflected by CV at 0 and 0.5 V is different with any kinds of oxygen functional groups characterized by TPD, but it is consistent with the SO2 catalytic oxidization/oxidation properties indicated by TPR.

  3. Influence of surface morphology and surface area on release behavior of hydrogen isotopes in LiNbO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Deqiong, E-mail: zhudeqiong@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Oda, Takuji [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Tanaka, Satoru [Department of Nuclear Engineering and Management, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 Japan (Japan)

    2014-11-15

    Surface processes have profound influence on tritium release behavior in ceramic breeder materials. In this paper, the release behavior of hydrogen isotopes in LiNbO{sub 3} is studied by thermal desorption spectroscopy (TDS) with focusing on the influence of the surface morphology and surface area. It is found that the amount of surface hydroxyl groups is proportional to the specific surface area and can be decreased by smoothing the surface roughness through heating pretreatment at high temperatures. The isotope exchange reaction between the surface hydroxyl groups and water molecules residue in the system is discussed and turns out to proceed fast. The release behavior of hydrogen isotopes in LiNbO{sub 3} is compared with that in Li{sub 2}TiO{sub 3} studied in our previous work. It reveals that LiNbO{sub 3} and Li{sub 2}TiO{sub 3} have similar surface environment and similar concentration of surface hydroxyl groups with the level of 10{sup 20} m{sup −2}. The formation mechanism of hydroxyl groups on the surface is discussed and a model to explain the experimental observations is proposed.

  4. Fabrication, surface properties, and origin of superoleophobicity for a model textured surface.

    Science.gov (United States)

    Zhao, Hong; Law, Kock-Yee; Sambhy, Varun

    2011-05-17

    ) from top to bottom. Comparable textured surfaces with (a) smooth straight side wall pillars and (b) straight side wall pillars with a 500 nm re-entrant structure made of SiO(2) were fabricated and the surfaces were made oleophobic with FOTS analogously. Contact angle data indicate that only the textured surfaces with the re-entrant pillar structure are both superoleophobic and superhydrophobic. The result suggests that the wavy structure at the top of each pillar is the main geometrical contributor to the superoleophobic property observed in the model surface.

  5. A surface wave elastography technique for measuring tissue viscoelastic properties.

    Science.gov (United States)

    Zhang, Xiaoming

    2017-04-01

    A surface wave elastography method is proposed to study the viscoelastic properties of skin by measuring the surface wave speed and attenuation on the skin. Experiments were carried out on porcine skin tissues. The surface wave speed is measured by the change of phase with distance. The wave attenuation is measured by the decay of wave amplitude with distance. The change of viscoelastic properties with temperature was studied at room and body temperatures. The wave speed was 1.83m/s at 22°C but reduced to 1.52m/s at 33°C. The viscoelastic ratio was almost constant from 22°C to 33°C. Fresh and decayed tissues were studied. The wave speed of the decayed tissue increased from 1.83m/s of fresh state to 2.73m/s. The viscoelastic ratio was 0.412/mm at the decayed state compared to 0.215/mm at the fresh state. More tissue samples are needed to study these viscoelastic parameters according to specific applications.

  6. Dynamic behavior of polymer surface and the time dependence of contact angle

    Institute of Scientific and Technical Information of China (English)

    WANG Xinping; CHEN Zhifang; SHEN Zhiquan

    2005-01-01

    Time-dependent contact angles were measured by depositing sessile drops of water on the polymer surfaces and monitoring the drop shape as a function of time. It was found that contact angles decreased sharply with contact time and the equilibrium contact angle was finally attained after a certain time. Values of starting (θs) and equilibrium contact angles (θe) obtained by the sessile drop method depend on polymer properties. The Wilhelmy plate technique was used to measure advancing and receding contact angles. The variations of starting (θs) and equilibrium contact angles (θe), advancing (θa) and receding contact angles (θr) have been studied on the oxidized surface of polymers containing polybutadiene block to explore the cause of time-dependence in contact angle measurement and the meaning of θs and θe. The results showed the linear relationships between starting (θs) and advancing contact angles (θa), the equilibrium (θe) and receding contact angles (θr). The similar relationship was also established between the contact angle hysteresis (θa-θr) and differences (θs-θe) in starting contact angles and equilibrium contact angles. Therefore, time-dependence in contact angle measurement was mainly attributed to the surface reconstruction when water drops were deposited on polymer surfaces. The starting contact angle was contributed by the hydrophobic component on polymer surface and the equilibrium contact angle mainly by the hydrophilic component of polymer. These results not only demonstrated the interdependency between two contact angle measurements, the sessile drop method and the Wilhelmy plate technique, but also provided the experimental evidence to explain the cause of time-dependent contact angle. This may also provide a new method to study dynamic behavior of polymer surface.

  7. Effects of hydroxylation and silanization on the surface properties of ZnO nanowires.

    Science.gov (United States)

    García Núñez, C; Sachsenhauser, M; Blashcke, B; García Marín, A; Garrido, Jose A; Pau, Jose L

    2015-03-11

    Silanization is commonly used to form bonds between inorganic materials and biomolecules as a step in the surface preparation of solid-state biosensors. This work investigates the effects of silanization with amino-propyldiethoxymethylsilane on hydroxylated sidewalls of zinc oxide (ZnO) nanowires (NWs). The surface properties and electrical characteristics of NWs are analyzed by different techniques after their hydroxylation and later silanization. Contact angle measurements reveal a stronger hydrophobic behavior after silanization, and X-ray photoelectron spectroscopy (XPS) results show a reduction of the surface dipole induced by the replacement of the hydroxyl group with the amine terminal group. The lower work function obtained after silanization in contact potential measurements corroborates the attenuation of the surface dipole observed in XPS. Furthermore, the surface band bending of NWs is determined from surface photovoltage measurements upon irradiation with UV light, yielding a 0.5 eV energy in hydroxylated NWs, and 0.18 eV, after silanization. From those results, a reduction in the surface state density of 3.1 × 10(11) cm(-2) is estimated after silanization. The current-voltage (I-V) characteristics measured in a silanized single NW device show a reduction of the resistance, due to the enhancement of the conductive volume inside the NW, which also improves the linearity of the I-V characteristic.

  8. Estimation of the Surface Properties of Styrene-Acrylonitrile Random Copolymers from Contact Angle Measurements.

    Science.gov (United States)

    Adão; Saramago; Fernandes

    1999-09-01

    The surface free energy per unit area of a solid, gamma(S), is a fundamental property of materials and determines their surface and interfacial behavior in processes like wetting and adhesion. In this study the gamma(S) of a series of styrene-acrylonitrile random copolymers is evaluated. Three different approaches are used to determine the components in which the surface free energy can be decomposed. Using the geometric and the harmonic mean approach, the dispersive, gamma(d), and polar, gamma(p), components of the solid surface free energy were determined and compared to the Lifshitz-van der Waals, gamma(LW), and acid-base, gamma(AB), components using the approach developed by C. J. van Oss et al. (1987, Adv. Colloid Interface Sci. 28, 35). The acid-base approach was also used to evaluate the work of adhesion of the test liquids: water, glycerol, and thiodiglycol. It was found that the contact angles of these liquids follow closely the predictions of Cassie equation. The evaluation of the surface free energy components on one hand and the relative magnitude of the work of adhesion components on the other hand, suggest that below 50% of acrylonitrile the polystyrene repeating units are preferentially at the surface. Above 50% of acrylonitrile the segregation of the low-energy homopolymer at the surface decreases. Copyright 1999 Academic Press.

  9. 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

  10. Bending Properties and Fracture Behavior of Ti-23Al-17Nb Alloy Laser Beam Welding Joints

    Institute of Scientific and Technical Information of China (English)

    WANG Guoqing; WU Aiping; ZOU Guisheng; ZHAO Yue; CHEN Qiang; REN Jialie

    2009-01-01

    Ti-23Al-17Nb alloy is an important high temperature structural material used in the space and aerospace fields. Welding of this alloy is an indispensable processing method, so the microstructures and mechanical properties of these welded joints must be studied to improve the welds. Longitudinal three-point bending tests were conducted to measure the bending ductility of laser beam welded joints. The crack dis-tribution and fracture surface were investigated to further analyze the fracture behavior. The results indicate that the bending ductility decreases as the heat input by the laser beam welding increases. The crack in-ducing strain reaches 4.24%, while the fracturing strain exceeds 5% when the heat input is below 316 J/cm. If the columnar crystal grain of the weld metal exhibits a uniform orientation, the bending ductility is worse. The fractography analysis shows that the cracking propagates transgranularly and the fracture surface has a cleavage mode.

  11. Derivation of surface properties from Magellan altimetry data

    Science.gov (United States)

    Lovell, Amy J.; Schloerb, F. Peter; McGill, George E.

    1992-12-01

    The fit of the Hagfors model to the Magellan altimetry data provides a means to characterize the surface properties of Venus. However, the derived surface properties are only meaningful if the model provides a good representation of the data. The Hagfors model provides a good representation of the data. The Hagfors model is generally a realistic fit to surface scattering properties of a nadir-directed antenna such as the Magellan altimeter; however, some regions of the surface of Venus are poorly described by the existing model, according to the goodness of fit parameter provided on the ARCDR CD-ROMs. Poorly characterized regions need to be identified and fit to new models in order to derive more accurate surface properties for use in inferring the geological processes that affect the surface in those regions. We have compared the goodness of fit of the Hagfors model to the distribution of features across the planet, and preliminary results show a correlation between steep topographic slopes and poor fits to the standard model, as has been noticed by others. In this paper, we investigate possible relations between many classes of features and the ability of the Hagfors model to fit the observed echo profiles. In the regions that are not well characterized by existing models, we calculate new models that compensate for topographic relief in order to derive improved estimates of surface properties. Areas investigated to date span from longitude 315 through 45, at all latitudes covered by Magellan. A survey of those areas yields preliminary results that suggest that topographically high regions are well suited to the current implementation of the Hagfors model. Striking examples of such large-scale good fits are Alpha Regio, the northern edges of Lada Terra, and the southern edge of Ishtar Terra. Other features that are typically well fit are the rims of coronae such as Heng-O and the peaks of volcanos such as Gula Mons. Surprisingly, topographically low regions, such

  12. 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

  13. Surface and Electrical Properties of Electro-Coagulated Thermal Waste

    Science.gov (United States)

    Yesilkaya, S. S.; Okutan, M.; Içelli, O.; Yalçın, Z.

    2015-05-01

    The Electro-Coagulated Thermal Waste (ECTW) sample of the impedance spectroscopy investigation for electrical modulus and conductivity are presented. Electrical properties via temperature and frequency dependent impedance spectroscopy were investigated. Real and imaginary parts of electrical modulus were measured at various frequencies and a related Cole-Cole plot was acquired as well. The surface resistivity of the ECTW was measured by the four-point probe measurement technique, yielding a relatively high surface resistivity. As a result of this study, an effective building shielding material, which is a cost effective alternative, is proposed. The activation energy values were calculated from the Arrhenius plots at different frequencies. The transition region in this plot may be attributed to activation of ionic conductivity at lower temperatures.

  14. Molecular dynamics simulations on surface properties of silicon dioxide melts

    CERN Document Server

    Röder, A

    2000-01-01

    In the present thesis the surface properties of a silicon dioxide melt were studied. As first systems drops (i.e. sytems without periodic boundary conditions) of N=432, 1536, as well as 4608 atoms were considered. The second analyzed geometry corresponds to that of a thin film, i. e. periodic boundary conditions in x- and y-direction were present, while in z-direction one had a free surface. In this case a system of N=1152 atoms was considered. As model potential the two-body potential proposed by Beest, Kramer, and van Santen was applied. For both geometries five temperatures were considered, which lied in the range of 3000 K

  15. Surface property modification of coatings via self-stratification

    Science.gov (United States)

    Pieper, Robert Joseph

    Biological fouling occurs everywhere in the marine environment and is a significant problem for marine vessels. Anti-fouling coatings have been used effectively to prevent fouling; however, these coatings harm non-targeted sea-life. Fouling-release coatings (FRC) appear to be an alternative way to combat fouling. FRC do not necessarily prevent the settlement of marine organisms but rather allow their easy removal with application of shear to the coatings surface. These coatings must be non-toxic, non-leaching, have low surface energy, low modulus, and durability to provide easy removal of marine organisms. Here the goal is to develop FRC based on thermosetting siloxane-polyurethane, amphiphilic polyurethane, and zwitterionic/amphiphilic polyurethane systems. A combinatorial high-throughput approach has been taken in order to explore the variables that may affect the performance of the final coatings. Libraries of acrylic polyols were synthesized using combinatorial high-throughput techniques by either batch or semi-batch processes. The design of the experiments for the batch and semi-batch processes were done combinatorially to explore a range of compositions and various reaction process variables that cannot be accomplished or are not suitable for single reaction experiments. Characterization of Rapid-GPC, high-throughput DSC, and gravimetrically calculated percent solids verified the effects of different reaction conditions on the MW, glass transition temperatures, and percent conversion of the different compositions of acrylic polyols. Coatings were characterized for their surface energy, pseudobarnacle pull-off adhesion, and were subjected to bioassays including marine bacteria, algae, and barnacles. From the performance properties results the acrylic polyol containing 20% hydroxyethyl acrylate and 80% butyl acrylate was selected for further siloxane-polyurethane formulations and were subjected to the same physical, mechanical, and performance testing

  16. Surface Characteristics and Adhesion Behavior of Escherichia coli O157:H7: Role of Extracellular Macromolecules

    Science.gov (United States)

    Surface macromolecule cleavage experiments were conducted on enterohaemorrhagic Escherichia coli O157:H7 cells to investigate the influence of these macromolecules on cell surface properties. Electrophoretic mobility, hydrophobicity, and titration experiments were carried out on proteinase K treate...

  17. A Facile Method to Modify the Characteristics and Corrosion Behavior of 304 Stainless Steel by Surface Nanostructuring toward Biomedical Applications.

    Science.gov (United States)

    Thangaraj, Balusamy; Nellaiappan, Sankara Narayanan T S; Kulandaivelu, Ravichandran; Lee, Min Ho; Nishimura, Toshiyasu

    2015-08-19

    The study addresses how surface nanostructuring of AISI 304 stainless steel (SS) by surface mechanical attrition treatment (SMAT) influences its characteristic properties and corrosion behavior in Ringer's solution. SMAT of 304 SS induced plastic deformation, enabled surface nanocrystallization, refined the grain size, transformed the austenite phase to strain induced α'-martensite phase, increased the surface roughness, induced defects/dislocations, imparted compressive residual stresses at the surface, decreased the contact angle, and increased surface energy. The change in properties of 304 SS following treatment using 5 and 8 mm ⌀ balls for 15, 30, 45, and 60 min has caused a deleterious influence on its corrosion resistance in Ringer's solution, while an improvement in corrosion behavior is observed for those treated using 2 mm ⌀ balls. The increase in surface roughness, transformation of the austenite to α'-martensite phase, a higher extent of deformation, and the presence of larger number of defects/dislocations are main factors responsible for the lower corrosion resistance observed for 304 SS treated using 5 and 8 mm ⌀ balls in Ringer's solution. In spite of having these attributes with a relatively lower extent, 304 SS treated using 2 mm ⌀ balls offered a better corrosion resistance and exhibits a better passivity. For those treated using 2 mm ⌀ balls, the ability of the nanocrystalline surface to promote passivation outweighs the deleterious influences caused by the limited amount of deformation and defects/dislocations. Based on the findings of this study, it is recommend that SMAT of 304 SS using 2 mm ⌀ balls for 15-30 min is the optimum condition to achieve the suitable surface profile, surface characteristics with better corrosion resistance.

  18. Antibacterial properties of biomedical surfaces containing micrometric silver islands

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Tanoira, R; Perez-Jorge, C; Endrino, J L; Gomez-Barrena, E; Horwat, D; Pierson, J F; Esteban, J, E-mail: rptanoira@fjd.es

    2010-11-01

    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. 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

  1. 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.

  2. 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.

  3. Probing anisotropic surface properties and interaction forces of chrysotile rods by atomic force microscopy and rheology.

    Science.gov (United States)

    Yang, Dingzheng; Xie, Lei; Bobicki, Erin; Xu, Zhenghe; Liu, Qingxia; Zeng, Hongbo

    2014-09-16

    Understanding the surface properties and interactions of nonspherical particles is of both fundamental and practical importance in the rheology of complex fluids in various engineering applications. In this work, natural chrysotile, a phyllosilicate composed of 1:1 stacked silica and brucite layers which coil into cylindrical structure, was chosen as a model rod-shaped particle. The interactions of chrysotile brucite-like basal or bilayered edge planes and a silicon nitride tip were measured using an atomic force microscope (AFM). The force-distance profiles were fitted using the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, which demonstrates anisotropic and pH-dependent surface charge properties of brucite-like basal plane and bilayered edge surface. The points of zero charge (PZC) of the basal and edge planes were estimated to be around pH 10-11 and 6-7, respectively. Rheology measurements of 7 vol % chrysotile (with an aspect ratio of 14.5) in 10 mM NaCl solution showed pH-dependent yield stress with a local maximum around pH 7-9, which falls between the two PZC values of the edge and basal planes of the rod particles. On the basis of the surface potentials of the edge and basal planes obtained from AFM measurements, theoretical analysis of the surface interactions of edge-edge, basal-edge, and basal-basal planes of the chrysotile rods suggests the yield stress maximum observed could be mainly attributed to the basal-edge attractions. Our results indicate that the anisotropic surface properties (e.g., charges) of chrysotile rods play an important role in the particle-particle interaction and rheological behavior, which also provides insight into the basic understanding of the colloidal interactions and rheology of nonspherical particles.

  4. Surface electrochemical properties of red mud (bauxite residue): zeta potential and surface charge density.

    Science.gov (United States)

    Liu, Yanju; Naidu, Ravendra; Ming, Hui

    2013-03-15

    The surface electrochemical properties of red mud (bauxite residue) from different alumina refineries in Australia and China were studied by electrophoresis and measuring surface charge density obtained from acid/base potentiometric titrations. The electrophoretic properties were measured from zeta potentials obtained in the presence of 0.01 and 0.001 M KNO(3) over a wide pH range (3.5-10) by titration. The isoelectric point (IEP) values were found to vary from 6.35 to 8.70 for the red mud samples. Further investigation into the surface charge density of one sample (RRM) by acid/base potentiometric titration showed similar results for pH(PZC) with pH(IEP) obtained from electrokinetic measurements. The pH(IEP) determined from zeta potential measurements can be used as a characteristic property of red mud. The minerals contained in red mud contributed to the different values of pH(IEP) of samples obtained from different refineries. Different relationships of pH(IEP) with Al/Fe and Al/Si ratios (molar basis) were also found for different red mud samples.

  5. 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

  6. Size dependence of surface thermodynamic properties of nanoparticles and its determination method by reaction rate constant

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenjiao; Xue, Yongqiang, E-mail: xyqlw@126.com; Cui, Zixiang

    2016-08-15

    Surface thermodynamic properties are the fundamental properties of nanomaterials, and these properties depend on the size of nanoparticles. In this paper, relations of molar surface thermodynamic properties and surface heat capacity at constant pressure of nanoparticles with particle size were derived theoretically, and the method of obtaining the surface thermodynamic properties by reaction rate constant was put forward. The reaction of nano-MgO with sodium bisulfate solution was taken as a research system. The influence regularities of the particle size on the surface thermodynamic properties were discussed theoretically and experimentally, which show that the experimental regularities are in accordance with the corresponding theoretical relations. With the decreasing of nanoparticle size, the molar surface thermodynamic properties increase, while the surface heat capacity decreases (the absolute value increases). In addition, the surface thermodynamic properties are linearly related to the reciprocal of nanoparticle diameter, respectively.

  7. Controllable surface morphology and properties via mist polymerization on a plasma-treated polymethyl methacrylate surface.

    Science.gov (United States)

    Wan, S J; Wang, L; Xu, X J; Zhao, C H; Liu, X D

    2014-02-14

    Surface modification by grafting polymers on solid materials is an important strategy used to improve surface properties. This article reports that under appropriate conditions, very thin layers with desired morphologies may be constructed on a plasma-treated substrate by feeding a small quantity of a monomer with a mist stream carrying droplets produced from monomer solutions. We investigate the effects of process parameters that affect layer morphology, including exposure time to the mist stream, concentration of the monomer solution, and solvent selectivity. For a methyl methacrylate solution in ethanol, nanoparticles are uniformly grown with increasing monomer concentration or exposure time and finally form a porous layer at 3.65 mol L(-1) for 30 min. Decreasing solvent polarity not only affects surface morphology, but also increases hydrophobicity of the resulting surface. With 2,2,3,4,4,4-hexafluorobutyl methacrylate as the monomer, SEM and AFM micrographs indicated that mist polymerization results in numerous microspheres on the activated surface. These experimental results were interpreted by a mechanism in terms of an in situ polymerization accompanied by a phase transformation of the resulting polymer. Specifically, plasma treatment provides highly active cations and radicals to initiate very rapid polymerization, and the resulting polymers are consequently deposited from the liquid onto the surface under phase transition mechanisms.

  8. The effects of yttrium on the hydrogenation performance and surface properties of a ruthenium-supported catalyst

    Directory of Open Access Journals (Sweden)

    LAITAO LUO

    2005-12-01

    Full Text Available The effects of yttrium on the hydrogenation performance and surface properties of a Ru/sepiolite catalyst were studied. With CO2 methanation and CS2 poisoning as the testing reactons, TPR, TPD, XRD and CO chemisorption as the characterizations, the results showed that the presence of yttrium can increase the hydrogenation activity and anti-poisoning capacity of the Ru/sepiolite catalyst, which is due to a change of surface properties of the Ru/sepiolite. In the process of the catalytic reaction, the adjusting behavior of yttrium for the Ru/sepiolite catalyst aids in increasing the catalytic activity and anti-poisoning capacity of the catalyst.

  9. 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.

  10. Surface properties of activated carbon from different raw materials

    Institute of Scientific and Technical Information of China (English)

    Zhang XiangLan; Zhang Yan; Liu Qiong; Zhou Wei

    2012-01-01

    Activated carbons (ACs) with different surface properties were prepared from different raw materials.N2 adsorption,pH value,Boehm titration,Temperature-programmed reduction (TPR) and FTIR were employed to characterize the pore structure and surface chemical properties of the ACs.The results show that AC from bituminous coal (AC-B) has more meso-pores,higher pH value,more carboxylic groups and basic site than ACs from coconut shell and hawthorn(AC-C,AC-H).Oxygen in the mixture gas has great effect on SO2 catalytic oxidation/oxidation ability of AC-B.In the absence of oxygen,the adsorbed SO2 on AC-B is 0.16 mmol/g and the conversion ratio of adsorbed SO2 to SO3 is 22,07%; while in the presence of oxygen,the adsorbed amount of SO2 is 0.42 mmol/g,and all of the adsorbed SO2 was totally converted to SO3.This feature of AC-B is consistent with its higher pH value,basic site and the reaction ability with H2 from TPR.The conversion ratios of SO2 absorbed on both AC-C and AC-H were 100%,respectively.

  11. Hyperspectral Remote Sensing of Atmosphere and Surface Properties

    Science.gov (United States)

    Liu, Xu; Zhou, Daniel K.; Larar, Allen M.; Yang, Ping

    2011-01-01

    Atmospheric Infrared Sounder (AIRS), Infrared Atmospheric Sounding Interferometer (IASI), and Cross-track Infrared Sounder (CrIS) are all hyper-spectral satellite sensors with thousands of spectral channels. Top of atmospheric radiance spectra measured by these sensors contain high information content on atmospheric, cloud, and surface properties. Exploring high information content contained in these high spectral resolution spectra is a challenging task due to computation e ort involved in modeling thousands of spectral channels. Usually, only very small fractions (4{10 percent) of the available channels are included in physical retrieval systems or numerical weather forecast (NWP) satellite data assimilations. We will describe a method of simultaneously retrieving atmospheric temperature, moisture, cloud, and surface properties using all available spectral channels without sacrificing computational speed. The essence of the method is to convert channel radiance spectra into super-channels by an Empirical Orthogonal Function (EOF) transformation. Because the EOFs are orthogonal to each other, about 100 super-channels are adequate to capture the information content of the radiance spectra. A Principal Component-based Radiative Transfer Model (PCRTM) developed at NASA Langley Research Center is used to calculate both the super-channel magnitudes and derivatives with respect to atmospheric profiles and other properties. There is no need to perform EOF transformations to convert super channels back to spectral space at each iteration step for a one-dimensional variational retrieval or a NWP data assimilation system. The PCRTM forward model is also capable of calculating radiative contributions due to multiple-layer clouds. The multiple scattering effects of the clouds are efficiently parameterized. A physical retrieval algorithm then performs an inversion of atmospheric, cloud, and surface properties in super channel domain directly therefore both reducing the

  12. Fabrication and anti-icing property of coral-like superhydrophobic aluminum surface

    Science.gov (United States)

    Zuo, Zhiping; Liao, Ruijin; Guo, Chao; Yuan, Yuan; Zhao, Xuetong; Zhuang, Aoyun; Zhang, YiYi

    2015-03-01

    Aluminum is one of the most widely used metals in transmission lines. Accumulation of ice on aluminum may cause serious consequences such as tower collapse and power failure. Here we develop a method to fabricate a coral-like superhydrophobic surface to improve its anti-icing performance via chemical etching and hot-water treatment. The as-prepared surface exhibited superhydrophobicity with a contact angle (CA) of 164.8 ± 1.1° and the sliding angle smaller than 1°. The static and dynamic anti-icing behaviors of the superhydrophobic surface in different conditions were systematically investigated using a self-made device and artificial climate laboratory. Results show that the coral-like superhydrophobic structure displayed excellent anti-icing property. The water droplet remained unfrozen on the as-prepared surface at -6 °C for over 110 min. 71% of the surface was free of ice when exposed in "glaze ice" for 30 min. This investigation proposed a new way to design an anti-icing surface which may have potential future applications in transmission lines against ice accumulation.

  13. Thermal behavior and Rheological Properties of PANI-DBSMPAN Blends

    Institute of Scientific and Technical Information of China (English)

    PAN Wei

    2007-01-01

    Conducting blends of polyacrylonitrile (PAN) copolymer and dodecylbenzene sulfonic acid doped polyaniline (PANI-DBSA) were prepared by solution blending of the two components.By means of various characterization methods including differential scanning calorimetry (DSC),thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and cone-plate rheometry,the effects of PANI-DBSA content on the thermal behavior, morphological and theological properties of the blends were investigated. A single and composition-dependent Tg was found for each of all blends and the thermal stability of PANI-DBSA/PAN was superior to that of both pure Co-PAN and PANI-DBSA. Rheological results show that the apparent viscosity of blend solution decreased at low PANI-DBSA content (2.5 wt%) while increased at high PANI-DBSA content (7.5wt%-10 wt%). Moreover, the shear-thinning appeared more distinctly with the incorporation of PANI-DBSA into the blend solutions especially at a high shear rate.

  14. 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.

  15. 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.

  16. Identification of rheological properties of human body surface tissue.

    Science.gov (United States)

    Benevicius, Vincas; Gaidys, Rimvydas; Ostasevicius, Vytautas; Marozas, Vaidotas

    2014-04-11

    According to World Health Organization obesity is one of the greatest public health challenges of the 21st century. It has tripled since the 1980s and the numbers of those affected continue to rise at an alarming rate, especially among children. There are number of devices that act as a prevention measure to boost person's motivation for physical activity and its levels. The placement of these devices is not restricted thus the measurement errors that appear because of the body rheology, clothes, etc. cannot be eliminated. The main objective of this work is to introduce a tool that can be applied directly to process measured accelerations so human body surface tissue induced errors can be reduced. Both the modeling and experimental techniques are proposed to identify body tissue rheological properties and prelate them to body mass index. Multi-level computational model composed from measurement device model and human body surface tissue rheological model is developed. Human body surface tissue induced inaccuracies can increase the magnitude of measured accelerations up to 34% when accelerations of the magnitude of up to 27 m/s(2) are measured. Although the timeframe of those disruptions are short - up to 0.2 s - they still result in increased overall measurement error.

  17. 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.

  18. Surface Properties of Bifidobacterial Strains of Human Origin

    Science.gov (United States)

    Pérez, Pablo F.; Minnaard, Yessica; Disalvo, Edgardo A.; De Antoni, Graciela L.

    1998-01-01

    The adherence of Bifidobacterium strains isolated from infant feces and commercial fermented dairy products to enterocyte-like cells was correlated with the autoagglutination and hemagglutination properties of these organisms. These results allowed us to define two groups: (i) cell-adherent bacteria showing hemagglutination and autoagglutination and (ii) non-cell-adherent, nonhemagglutinating, nonautoagglutinating bacteria. Glass adherence was shown to be nonspecific and was discarded as a criterion for selection of adherent cells. Hydrophobicity appeared to be necessary for adhesion to enterocyte-like cells and autoagglutination. Adhesive strains were highly hydrophobic, and the degree of adherence was slightly dependent on the surface potential. Cells autoagglutinated more when the electrostatic negative charges on the cell surface were shielded by a decrease in the pH from 7 to 2. However, in some strains negative charges at the cell surface were adjuvant to adhesion, thus suggesting that specific chemical interactions occurred. The present results provide a method for preliminary selection of bacteria potentially adherent to epithelial cells by means of autoagglutination. PMID:9435057

  19. Physico-chemical properties of PDMS surfaces suitable as substrates for cell cultures

    Science.gov (United States)

    Raczkowska, Joanna; Prauzner-Bechcicki, Szymon; Lukes, Jaroslav; Sepitka, Josef; Bernasik, Andrzej; Awsiuk, Kamil; Paluszkiewicz, Czesława; Pabijan, Joanna; Lekka, Małgorzata; Budkowski, Andrzej

    2016-12-01

    Elastic properties of the substrate have profound effect on adhesion and proliferation of cells. Here, we introduce a method to produce polydimethylsiloxane (PDMS) substrates with stiffness tuned monotonically from 1.67 to 0.24 MPa, by the time of UV irradiation adjusted up to 5 h. The Young's modulus (determined by using nanoindenter) scales linearly with stiffness calculated using AFM-based force spectroscopy data. Such a relation enables the determination of the Young modulus from AFM force - distance curves also when the Herz model is not applicable. Our findings demonstrate that surface properties of PDMS substrates are not affected by the applied methodology of tuning substrate elasticity. Finally, the colorimetric proliferation assay (MTT) carried out for non-malignant (HCV29) and cancerous (T24) bladder cancer cells depicted a significant contribution of PDMS substrate elasticity to the behavior of cells. The softer PDMS substrate demonstrated excellent cytocompatibility whereas the stiff one is more cell-repellent.

  20. Enhanced Thermoelectric Properties of In-Doped ZnSb Thin Film with Surface Nanocrystallization

    Science.gov (United States)

    Zheng, Zhuang-hao; Fan, Ping; Luo, Jing-ting; Liang, Guang-xing

    2017-02-01

    This work establishes the high-temperature properties of In-doped ZnSb thin films prepared by a multistep cosputtering method on flexible substrates. The microstructure and thermoelectric properties of the In-doped ZnSb thin films were investigated. X-Ray diffraction results indicated that the main peaks of the In-doped ZnSb thin films were related to ZnSb phase, with some nanocrystallization on the surface after In doping. All samples exhibited p-type conduction behavior, with increased Seebeck coefficient after In doping. The thermal conductivity decreased sharply for the In-doped samples with nanocrystallization, resulting in a ZT value almost six times higher than for undoped ZnSb thin film.

  1. 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.

  2. Combined surface acoustic wave and surface plasmon resonance measurement of collagen and fibrinogen layer physical properties

    Directory of Open Access Journals (Sweden)

    J.-M. Friedt

    2016-12-01

    Full Text Available We use an instrument combining optical (surface plasmon resonance and acoustic (Love mode surface acoustic wave device real-time measurements on a same surface for the identification of water content in collagen and fibrinogen protein layers. After calibration of the surface acoustic wave device sensitivity by copper electrodeposition and surfactant adsorption, the bound mass and its physical properties – density and optical index – are extracted from the complementary measurement techniques and lead to thickness and water ratio values compatible with the observed signal shifts. Such results are especially usefully for protein layers with a high water content as shown here for collagen on an hydrophobic surface. We obtain the following results: collagen layers include 70±20% water and are 16±3 to 19±3 nm thick for bulk concentrations ranging from 30 to 300 μg/ml. Fibrinogen layers include 50±10% water for layer thicknesses in the 6±1.5 to 13±2 nm range when the bulk concentration is in the 46 to 460 μg/ml range.

  3. Monitoring polymer properties using shear horizontal surface acoustic waves.

    Science.gov (United States)

    Gallimore, Dana Y; Millard, Paul J; Pereira da Cunha, Mauricio

    2009-10-01

    Real-time, nondestructive methods for monitoring polymer film properties are increasingly important in the development and fabrication of modern polymer-containing products. Online testing of industrial polymer films during preparation and conditioning is required to minimize material and energy consumption, improve the product quality, increase the production rate, and reduce the number of product rejects. It is well-known that shear horizontal surface acoustic wave (SH-SAW) propagation is sensitive to mass changes as well as to the mechanical properties of attached materials. In this work, the SH-SAW was used to monitor polymer property changes primarily dictated by variations in the viscoelasticity. The viscoelastic properties of a negative photoresist film were monitored throughout the ultraviolet (UV) light-induced polymer cross-linking process using SH-SAW delay line devices. Changes in the polymer film mass and viscoelasticity caused by UV exposure produced variations in the phase velocity and attenuation of the SH-SAW propagating in the structure. Based on measured polymer-coated delay line scattering transmission responses (S(21)) and the measured polymer layer thickness and density, the viscoelastic constants c(44) and eta(44) were extracted. The polymer thickness was found to decrease 0.6% during UV curing, while variations in the polymer density were determined to be insignificant. Changes of 6% in c(44) and 22% in eta(44) during the cross-linking process were observed, showing the sensitivity of the SH-SAW phase velocity and attenuation to changes in the polymer film viscoelasticity. These results indicate the potential for SH-SAW devices as online monitoring sensors for polymer film processing.

  4. Galvanic effects on electrochemical behaviors of bare surface of 304 stainless steel

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The bare surface of 304 stainless steel is produced by the fast fracture method. The influence of the surfacegalvanic cell on the electrochemical behaviors of bare surface of 304 stainless steel has been investigated in H2SO4 solutionswith different concentrations. The results show that the solution corrosivity level and the area ratio influence the surfacegalvanic effects caused by the inhomogeneity between the free-film surface of alloy and the passive surface. The surfacegalvanic effects can speed up the dissolution rate of the bare surface of the alloy and will change the electrochemical behav-ior of bare surface. With the increase of the area ratio between passive surface and fractured surface, the galvanic potentialbecomes more positive and, in the range of passive potential, both galvanic current and the peak fracture current increase

  5. 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.

  6. 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....

  7. Heat-Affected Behavior of the Magnetic Properties of Iron Nano-Particles

    Institute of Scientific and Technical Information of China (English)

    柳刚; 吕楠; 秦伯雄; 范荣焕; 郭院波

    2004-01-01

    The high surface energy makes metal nano-particles reactive and easy to get oxidized or burned in the open air, which results in decreasing or entirely losing their functions and properties. In this paper, the mag netic property behavior of iron nano-particle, which is one kind of the typical magnetic nano-materials, has been investigated. The iron nano-particles were heated to different temperatures in an open-air stove. After that, they were firstly examined by TEM to observe the changes of their outline of shapes and then measured by VSM to trace the changes of their magnetic properties. The test results show that iron nano-particles can keep their magnetic property with saturation magnetic induction intensity B, around 136-161 emu/g, remanent magnetic induction intensity Br around 14.8-17.4 emu/g and coercive force Hc around 290-302 Oe when the temperature goes up to 523 K. The explanation to such outstanding oxidization-proof ability has been given that there exists a single crystal and lattice-shared Gamma-Fe2O3 shell covering the pure iron core, which prevents the spherical iron nano-particles from further oxidization.

  8. 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.

  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.

  10. Effect of heat treatment on structure, surface composition, infrared emission and surface electrical properties of tourmaline

    Science.gov (United States)

    He, Dengliang; Liu, Shuxin

    2017-02-01

    Crystal structure, surface composition, infrared emission properties and surface electrical properties of tourmaline from Guangxi of China, when subjected to heat treatment in air atmosphere had been studied by some methods, including X-ray fluorescence spectrum (XRF), X-ray diffraction (XRD) meter, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), energy dispersion spectroscopy (EDS), scanning electron microscope (SEM) and Zeta potential analyzer, etc. Experimental results show that the unit cell of tourmaline would shrink during heat treatment because Fe2+ were oxidized. Moreover, the Fe3+/Fetotal inside tourmaline can be raised after treatment. Infrared normal total emissivity of tourmaline reaches 0.87, and infrared radiation energy density is 4.56 × 102W/m2. It can maintain excellent infrared emission properties at high temperature. Simultaneously, tourmaline presents negative Zeta potential in the aqueous solution, and its Zeta potential reaches ‑18.04 mV. Zeta potential of tourmaline was increased to ‑24.83 mV after heat treatment at 400∘C, and decrease to ‑11.78 mV after heat treatment at 600∘C. These findings may provide reference data for tourmaline’s application in the field of functional materials.

  11. The Vaporization Behavior of a Fuel Drop on a Hot Surface

    Science.gov (United States)

    1977-11-01

    evaporation behavior of fuel drops 99 Figure 36. Effect of surface cleanliness on drop evaporation lifetime .. ......... . 101 Figure 37. Effect of drop...C, CD 0 C) - -C) -H _______________C_ 100 procedures that were considered during the evaluation included the surface cleanliness , fuel drop size and...evaporating surface heating rate. The effect of the studied variables on the test results was found to be as follow: Surface Cleanliness As indicated

  12. Modeling and analysis of the electromechanical behavior of surface-bonded piezoelectric actuators using finite element method

    CERN Document Server

    Yu, Huangchao

    2016-01-01

    Piezoelectric actuators have been widely used to form a self-monitoring smart system to do Structural health monitoring (SHM). One of the most fundamental issues in using actuators is to determine the actuation effects being transferred from the actuators to the host structure. This report summaries the state of the art of modeling techniques for piezoelectric actuators and provides a numerical analysis of the static and dynamic electromechanical behavior of piezoelectric actuators surface-bonded to an elastic medium under in-plane mechanical and electric loads using finite element method. Also case study is conducted to study the effect of material properties, bonding layer and loading frequency using static and harmonic analysis of ANSYS. Finally, stresses and displacements are determined, and singularity behavior at the tips of the actuator is proved. The results indicate that material properties, bonding layers and frequency have a significant influence on the stresses transferred to the host structure.

  13. 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.

  14. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Leib, Jeffrey Scott [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    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, Hc in cases 1, 3, and 5, and the uniaxial character of the Gd5(Si2Ge2), 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, Ms, 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

  15. 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

  16. Thermophysical Properties of the Lunar Surface from Diviner Observations

    Science.gov (United States)

    Hayne, Paul; Bandfield, Joshua; Vasavada, Ashwin; Ghent, Rebecca; Siegler, Matthew; Williams, Jean-Pierre; Greenhagen, Benjamin; Aharonson, Oded; Paige, David

    2013-04-01

    Orbital thermal infrared measurements are sensitive to a variety of properties of the Moon's surface layer, including rock abundance, regolith cover and porosity, and small-scale surface roughness. With its multiple spectral channels and large dynamic temperature range, the Diviner Lunar Radiometer [1] on NASA's LRO spacecraft has enabled the first global, high-resolution maps of these important thermophysical properties. Here we present a summary of the results of Diviner's thermophysical investigation thus far. Maps of surface rock abundance show low typical values of decrease systematically with crater age, and rocky surfaces are only preserved on the youngest craters (decrease from ~10 kg m-2 yr-1 for crater ages of ~1 Ma to ~1 mg m-2 yr-1 at ~1 Ga [4]. Variations in upper regolith density correlate with the ages of individual mare basalt units, suggesting this layer is actively processed by impacts on geologically short timescales, which may reveal age relationships previously unseen [5]. Vast cold regions surrounding fresh impact craters during lunar night (termed "cold spots") are only apparent in thermal infrared data [2]. These features cannot be explained by the emplacement of ejecta, and instead are well modeled by the in situ decompression of the top ~1-10 cm of regolith. Among a variety of explanations for this phenomenon, a model of grain lifting and turbulent mixing within an expanding vapor cloud best matches observations. The Diviner observations suggest impact vaporization leads to prominent yet ephemeral scars in the upper regolith that may be common on airless bodies in the Solar System. Surface roughness at scales smaller than the ~250 m Diviner footprint affects the measured spectral slope in brightness temperatures. We used Diviner brightness temperature spectra measured at a variety of solar illumination and viewing geometries to constrain and map the RMS slopes of the Moon's surface [6]. Due to the general increase in roughness at smaller

  17. 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.

  18. Dynamic Behaviors of Contact Lines on Micropillared Hydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Chen-chuan Tan

    2016-01-01

    Full Text Available The dynamic characteristics of contact lines on inclined micropillared surfaces were investigated in this paper. It was observed that the contact lines varied gradually to a ladder shape with the droplet sliding on micropillared surfaces under Wenzel state. The dynamic deformation of contact lines would be more obvious under Wenzel state and Cassie impregnating state; however it is negligible when the droplet is in one-dimensional scenario. Droplet layers formed during droplet sliding were left behind and evaporated quickly and disappeared. Based on these characteristics, the comparison of experimental data with theoretical models was discussed. It was found that energy barrier played an important role in analyzing wetting characteristics. Because of ignoring the role of energy barrier, the model of sliding angle cannot predict the sliding angle on micropillared surfaces very well, especially when the area fraction is small. This work is helpful to propose a more accuracy sliding angle model.

  19. E. coli Surface Properties Differ between Stream Water and Sediment Environments

    Directory of Open Access Journals (Sweden)

    Xiao Liang

    2016-11-01

    Full Text Available The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10mM and 22˚C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity and extracellular polymeric substance (EPS composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli. A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli. Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG5 genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli.

  20. 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.

  1. Relevance of glycosylation of S-layer proteins for cell surface properties.

    Science.gov (United States)

    Schuster, Bernhard; Sleytr, Uwe B

    2015-06-01

    Elucidating the building principles and intrinsic features modulating certain water-associated processes (e.g., surface roughness in the nanometer scale, surface hydration and accompanied antifouling property, etc.) of surface structures from (micro)organisms is nowadays a highly challenging task in fields like microbiology, biomimetic engineering and (bio)material sciences. Here, we show for the first time the recrystallization of the wild-type S-layer glycoprotein wtSgsE from Geobacillus stearothermophilus NRS 2004/3a and its recombinantly produced non-glycosylated form, rSgsE, on gold sensor surfaces. Whereas the proteinaceous lattice of the S-layer proteins is forming a rigid layer on the sensor surface, the glycan chains are developing an overall soft, highly dissipative film. Interestingly, to the wtSgsE lattice almost twice the amount of water is bound and/or coupled in comparison with the non-glycosylated rSgsE with the preferred region being the extending glycan residues. The present results are discussed in terms of the effect of the glycan residues on the recrystallization, the adjoining hydration layer, and the nanoscale roughness and fluidic behavior. The latter features may turn out to be one of the most general ones among bacterial and archaeal S-layer lattices.

  2. Surface Behavior of Rhodamin and Tartrazine on Silica-Cellulose Sol-Gel Surfaces by Thin Layer Elution

    Directory of Open Access Journals (Sweden)

    Surjani Wonorahardjo

    2016-05-01

    Full Text Available Physical and chemical interactions are the principles for different types of separation systems as the equillibrium dynamics on surface plays a key-role. Surface modification is a way for selective separation at interfaces. Moreover, synthesis of gel silica by a sol-gel method is preferred due to the homogeneity and surface feature easily controlled. Cellulose can be added in situ to modified the silica features during the process. Further application for to study interaction of rhodamin and tartrazine in its surface and their solubilities in mobile phase explains the possibility for their separation. This paper devoted to evaluate the surface behavior in term of adsorption and desorption of tartrazine and rhodamin on silica-cellulose thin layer in different mobile phase. Some carrier liquids applied such as methanol, acetone, n-hexane and chloroform. The result proves tartrazine and rhodamin is separated and have different behavior in different mobile phase. The retardation factors (Rf of the mixtures suggest complexity behavior on silica-cellulose surface.

  3. Microstructure, Tensile Properties and Work Hardening Behavior of GTA-Welded Dual-Phase Steels

    Science.gov (United States)

    Ashrafi, H.; Shamanian, M.; Emadi, R.; Saeidi, N.

    2017-03-01

    In the present study, microstructure, tensile properties and work hardening behavior of a DP700 steel after gas tungsten arc welding were investigated. Formation of bainite in the fusion zone resulted in a hardness increase compared to that for the base metal (BM), whereas tempering of the pre-existing martensite in the subcritical heat-affected zone (HAZ) led to softening. The GTA-welded joint exhibited a continuous yielding behavior and a yield strength close to that for the BM, while its ultimate tensile strength and total elongation were lower than those for the BM owing to the formation of soft zone in the HAZ. A joint efficiency of about 81% was obtained for the GTA-welded joint, and it failed in the softened HAZ. Analysis of work hardening based on the Kocks-Mecking approach showed one stage of hardening behavior corresponding to the stage III for both the DP700 BM and welded sample. It was also revealed that the DP700 BM has larger values of work hardening exponent and magnitude of work hardening compared with the welded sample. Analysis of fractured surfaces showed that the dominant fracture mode for both the DP700 BM and welded joint was ductile.

  4. 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.

  5. Surface Behavior of Bioactive Glass of Si-Na-Ca-P System in Simulated Body Fluid

    Science.gov (United States)

    Ma, Jie; Chen, Chuanzhong; Wang, Diangang; Dang, Xing; Bao, Ruiliang; Yao, Liang

    Glass of the Si-Na-Ca-P system has been synthesized by normal melting and annealing technique. The obtained glass powders and annealed blocks were showed to be amorphous by X-ray diffraction (XRD). The thermal properties of glasses were analyzed by differential scanning calorimetry (DSC), it showed that the glass transformation temperature (Tg) was 556.3°C. The behavior of annealed glass discs in simulated body fluid solution (SBF) was studied in polyethylene containers at a constant temperature of 37°C for different time up to 14 days. The changes in the surface morphology and composition were observed by electronic probe microanalyzer (EPMA) associated with energy dispersive spectroscopy (EDS). Glass surface changed quickly as soon as immersion took place, and after longer soaking time, it showed different superimposed internal and external layers, which were identified as SiO2-rich and CaO-P2O5-rich layers, and on the external layer, spherical particles were also discovered.

  6. Statistical mechanics study on wetting behaviors of Ne on Mg surface

    Science.gov (United States)

    Zhou, S.; Zhang, M.

    2017-04-01

    Wetting behavior of Ne adsorbed on a Mg surface, first investigated by means of a grand canonical Monte Carlo method in a previous publication (M. J. Bojan, G. Stan, S. Curtarolo, W. A. Steele, and M. W. Cole, Phys. Rev. E, 1999, 59, 864), is again studied by means of classical density functional theory. The Ne-Ne interaction is taken to be of the Lennard-Jones form, while the Ne-surface interaction is derived from an electronic density functional theory. The wetting phase diagram is calculated, and the isotherm shapes, energy and structural properties of the adsorbed films are examined. The present calculations indicate that the system exhibits first-order pre-wetting transition at temperatures above a wetting temperature of Tw≈24 K, and below a critical pre-wetting temperature of Tpwc≈25.09 K. The present findings include (i) in the pre-wetting temperature region, the pre-wetting transition is mixed with many layering transitions; after pre-wetting, the film thickness discontinuously increases (due to frequent occurrences of the layering transitions) and eventually diverges as the chemical potential approaches and eventually equals the saturation value. (ii) Occurrence of the layering transition remains above Tpwc, and the increase of the film thickness with the chemical potential is discontinuous. (iii) Below the wetting temperature, the layering transitions frequently occur and tend to gather together more closely as the saturation is approached.

  7. Substrate texture properties induce triatomine probing on bitten warm surfaces

    Directory of Open Access Journals (Sweden)

    Lorenzo Marcelo G

    2011-06-01

    Full Text Available Abstract Background In this work we initially evaluated whether the biting process of Rhodnius prolixus relies on the detection of mechanical properties of the substrate. A linear thermal source was used to simulate the presence of a blood vessel under the skin of a host. This apparatus consisted of an aluminium plate and a nickel-chrome wire, both thermostatized and presented at 33 and 36°C, respectively. To evaluate whether mechanical properties of the substrate affect the biting behaviour of bugs, this apparatus was covered by a latex membrane. Additionally, we evaluated whether the expression of probing depends on the integration of bilateral thermal inputs from the antennae. Results The presence of a latex cover on a thermal source induced a change in the biting pattern shown by bugs. In fact, with latex covered sources it was possible to observe long bites that were never performed in response to warm metal surfaces. The total number of bites was higher in intact versus unilaterally antennectomized insects. These bites were significantly longer in intact than in unilaterally antennectomized insects. Conclusions Our results suggest that substrate recognition by simultaneous input through thermal and mechanical modalities is required for triggering maxillary probing activity.

  8. Surface molecular aggregation structure and surface physicochemical properties of poly(fluoroalkyl acrylate) thin films

    Science.gov (United States)

    Honda, K.; Yamaguchi, H.; Kobayashi, M.; Morita, M.; Takahara, A.

    2008-03-01

    Effect of side chain length on the molecular aggregation states and surface properties of poly(fluoroalkyl acrylate)s [PFA-Cy, where y is fluoromethylene number in Rf group] thin films were systematically investigated. Spin-coated PFA-Cy thin films were characterized by static and dynamic contact angle measurements, X-ray photoelectron spectroscopy (XPS), and grazing- incidence X-ray diffraction (GIXD). The receding contact angles showed small values for PFA-Cy with short side chain (y=8. GIXD revealed that fluoroalkyl side chain of PFA-Cy with y>=8 was crystallized and formed ordered structures at the surface region as well as bulk one. These results suggest that water repellent mechanism of PFA-Cy can be attributed to the presence of highly ordered fluoroalkyl side chains at the outermost surfaces. The results of XPS in the dry and hydrated states and contact angle measurement in water support the mechanism of lowering contact angle for water by exposure of carbonyl group to the water interface through reorientation of short fluoroalkyl chains. The surface nanotextured PFA-C8 through imprinting of anodic aluminum oxide mold showed extremely high hydrophobicity as well as high oleophobicity.

  9. Surface molecular aggregation structure and surface physicochemical properties of poly(fluoroalkyl acrylate) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Honda, K; Yamaguchi, H; Takahara, A [Graduate School of Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka, 819-0395 (Japan); Kobayashi, M [Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka, 819-0395 (Japan); Morita, M [Fundamental Research Department, Chemical Division, Daikin Industries, Ltd., 1-1 Nishi Hitotsuya, Settsu-shi, Osaka 566-8585 (Japan)], E-mail: takahara@cstf.kyushu-u.ac.jp

    2008-03-15

    Effect of side chain length on the molecular aggregation states and surface properties of poly(fluoroalkyl acrylate)s [PFA-C{sub y}, where y is fluoromethylene number in R{sub f} group] thin films were systematically investigated. Spin-coated PFA-C{sub y} thin films were characterized by static and dynamic contact angle measurements, X-ray photoelectron spectroscopy (XPS), and grazing- incidence X-ray diffraction (GIXD). The receding contact angles showed small values for PFA-C{sub y} with short side chain (y{<=}6) and increased above y{>=}8. GIXD revealed that fluoroalkyl side chain of PFA-C{sub y} with y{>=}8 was crystallized and formed ordered structures at the surface region as well as bulk one. These results suggest that water repellent mechanism of PFA-C{sub y} can be attributed to the presence of highly ordered fluoroalkyl side chains at the outermost surfaces. The results of XPS in the dry and hydrated states and contact angle measurement in water support the mechanism of lowering contact angle for water by exposure of carbonyl group to the water interface through reorientation of short fluoroalkyl chains. The surface nanotextured PFA-C{sub 8} through imprinting of anodic aluminum oxide mold showed extremely high hydrophobicity as well as high oleophobicity.

  10. 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...

  11. Effect of Surface Treated Silicon Dioxide Nanoparticles on Some Mechanical Properties of Maxillofacial Silicone Elastomer

    Directory of Open Access Journals (Sweden)

    Sara M. Zayed

    2014-01-01

    Full Text Available Current materials used for maxillofacial prostheses are far from ideal and there is a need for novel improved materials which mimic as close as possible the natural behavior of facial soft tissues. This study aimed to evaluate the effect of adding different concentrations of surface treated silicon dioxide nanoparticles (SiO2 on clinically important mechanical properties of a maxillofacial silicone elastomer. 147 specimens of the silicone elastomer were prepared and divided into seven groups (n=21. One control group was prepared without nanoparticles and six study groups with different concentrations of nanoparticles, from 0.5% to 3% by weight. Specimens were tested for tear strength (ASTM D624, tensile strength (ASTM D412, percent elongation, and shore A hardness. SEM was used to assess the dispersion of nano-SiO2 within the elastomer matrix. Data were analyzed by one-way ANOVA and Scheffe test (α=0.05. Results revealed significant improvement in all mechanical properties tested, as the concentration of the nanoparticles increased. This was supported by the results of the SEM. Hence, it can be concluded that the incorporation of surface treated SiO2 nanoparticles at concentration of 3% enhanced the overall mechanical properties of A-2186 silicone elastomer.

  12. 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.

  13. 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.

  14. 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.

  15. The effect of the nanosize on surface properties of NiO nanoparticles for the adsorption of Quinolin-65.

    Science.gov (United States)

    Marei, Nedal N; Nassar, Nashaat N; Vitale, Gerardo

    2016-03-07

    Using Quinolin-65 (Q-65) as a model-adsorbing compound for polar heavy hydrocarbons, the nanosize effect of NiO nanoparticles on the adsorption of Q-65 was investigated. Different-sized NiO nanoparticles with sizes between 5 and 80 nm were prepared by the controlled thermal dehydroxylation of Ni(OH)2. The properties of the nanoparticles were characterized using XRD, BET, FTIR, HRTEM and TGA. The effects of the nanosize on the textural properties, the shape and the morphology were studied. The adsorption of Q-65 molecules onto different-sized nanoparticles was tested in toluene-based solutions. On a normalized surface area basis, the number of Q-65 molecules adsorbed per nm(2) of the NiO surface was the highest for NiO nanoparticles of size 80 nm, while that for 5 nm sized NiO nanoparticles was the lowest. Excitingly, the adsorption capacity of other NiO sizes varied from loading suggesting different adsorption behavior, which exhibits the significance of textural properties during the adsorption of Q-65. Computational modeling of the interaction between the Q-65 molecule and the NiO nanoparticle surface was carried out to get more understanding of its adsorption behavior. A number of factors contributing to the enhanced adsorption capacity of nanoscale NiO were determined. These include surface reactivity, topology, morphology and textural properties.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, In Tae; Jung, Chan Hee; Nh, Young Chang; Choi, Jae Hak [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kuk, In Seol [Hanyang University, Seoul (Korea, Republic of); An, Mi Young [Chungnam National University, Daejeon (Korea, Republic of)

    2009-12-15

    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.

  17. Curvature properties of the slowness surface of the system of crystal acoustics for cubic crystals

    OpenAIRE

    LIESS, Otto

    2008-01-01

    In this paper we study geometric properties of the slowness surface of the system of crystal acoustics for cubic crystals. In particular we shall study curvature properties of the surface and the behaviour of the surface near singular points. The main result is that in the generic nearly isotropic case there are no planes which are tangent to the surface along entire curves. This is in contrast with what happens for the slowness surface of the system of crystal optics for...

  18. 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

    2012-10-09

    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

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

    Institute of Scientific and Technical Information of China (English)

    Lü; Yongjun

    2006-01-01

    [1]Basu J K,Hazra S,Sanyal M K.Growth mechanism of Langmuir-Blodgett films.Phys Rev Lett,1999,82:4675-4678[2]Taylor R S,Shields R L.Molecular-dynamics simulations of the ethanol liquid-vapor interface.J Chem Phys,2003,119:12569-12576[3]Velev O D,Gurkov T D,Ivanov I B,et al.Abnormal thickness and stability of nonequilibrium liquid films.Phys Rev Lett,1995,75:264-267[4]Weng J G,Park S,Lukes J R,et al.Molecular dynamics investigation of thickness effect on liquid films.J Chem Phys,2000,113:5917-5923[5]Zakharov V V,Brodskaya E N,Laaksonen A.Surface tension of water droplets:A molecular dynamics study of model and size dependencies.J Chem Phys,1997,107:10675-10683[6]Wang J Z,Chen M,Guo Z Y.A two-dimensional molecular dynamics simulation of liquid-vapor nucleation.Chin Sci Bull,2003,48(7):623-626[7]Guissani Y,Guillot B.A computer simulation study of the liquid-vapor coexistence curve of water.J Chem Phys,1993,98:8221-8235[8]Wilson M A,Pohorille A,Pratt L R.Surface potential of the water liquid-vapor interface.J Chem Phys,1988,88:3281-3285[9]Alejandre J,Tildesley D J,Chapela G A.Molecular dynamics simulation of the orthobaric densities and surface tension of water.J Chem Phys,1995,102:4574-4583[10]Matsumoto M,Kataoka Y.Study on liquid-vapor interface of water (Ⅰ):Simulational results of thermodynamic properties and orientational structure.J Chem Phys,1988,88:3233-3245[11]Floriano M A,Angell C A.Surface tension and molar surface free energy and entropy of water to-27.2℃.J Phys Chem,1990,94:4199-4202[12]Jorgensen W L,Chandrasekhar J,Madura J D.Comparison of simple potential functions for simulating liquid water.J Chem Phys,1993,79:926-935[13]Berendsen H J C,Grigera J R,Straatsma T P.The missing term in effective pair potentials.J Phys Chem,1987,91:6269-6271[14]Arbuckle B W,Clancy P.Effects of the Ewald sum on the free energy of the extended simple point charge model for water.J Chem Phys,2002,116:5090-5098[15]Tarazona P,Chacon E,Reinaldo-Falagan M,et al

  20. The effects of surface functionalization on rheology, structure and transport properties of nanocomposites

    Science.gov (United States)

    Ranka, Moulik A.

    In this thesis, the effects of surface functionalization using hydrophobic silanes on properties of nanocomposites comprising 42 nm silica particles suspended in a melt of polyethylene-glycol (PEG) are studied using rheological, static and dynamic x-ray scattering studies. The nanocomposites are studied in the low molecular weight unentangled (PEG-400) and high molecular weight entangled (PEG-20000) regimes. We find no differences in the properties of the bare and silanized particles in the low volume fraction regime up to where the interparticle separation distance h > 6Rg. In the region of 6Rg > h > 3Rg (5Rg > h > 3Rg, in case of entangled melts), we find substantial differences in the rheological, structure and transport properties when comparing the bare and silanized particles. In the unentangled melts, we observe up to four orders of magnitude drop in the viscosity of the composites at the highest levels of silanization and observe shear thinning behavior that is unlike what is universally seen for hard spheres. For the entangled melts, a yield stress is observed for the silanized particles that is absent in the case of the bare particles and there is a divergence in the elastic modulus in comparison to bare particles. We observe an anomalous speed up in the density relaxations and an associated maxima in structure properties in the case of unentangled melts which has been reported previously for particles experiencing soft repulsive potentials. A clear reentrant behavior in structure and transport properties is observed for bare particles in the entangled melts that have been previously reported for particles interacting with soft repulsive potentials such as square shoulder and ramp potentials. In the silanized systems, the density relaxation times although lower than bare particles, is ii unaffected by increasing volume fraction up to h ~ 3Rg and is decoupled from the structure properties which are non-monotonic similar to bare particles. In the region of

  1. 78 FR 37660 - American Surface Lines, LLC-Acquisition and Operation Exemption-Mikrut Properties, LLLP

    Science.gov (United States)

    2013-06-21

    ... Surface Transportation Board American Surface Lines, LLC--Acquisition and Operation Exemption--Mikrut Properties, LLLP American Surface Lines, LLC (ASL), a noncarrier, has filed a verified notice of exemption under 49 CFR 1150.31 to acquire by assignment from Mikrut Properties, LLLP (MP), and to operate as...

  2. Surface structure and properties of biomedical NiTi shape memory alloy after Fenton's oxidation.

    Science.gov (United States)

    Chu, C L; Hu, T; Wu, S L; Dong, Y S; Yin, L H; Pu, Y P; Lin, P H; Chung, C Y; Yeung, K W K; Chu, Paul K

    2007-09-01

    intrinsic electrical characteristics of the titania film. The titania film produced by Fenton's oxidation has good mechanical stability and does not adversely impact the shape memory behavior of NiTi. Our work suggests that Fenton's oxidation is a promising low-temperature, low-cost surface modification method for improving the surface properties of biomedical NiTi SMA.

  3. Characterization of adhesion associated surface properties of uropathogenic Escherichia coli.

    Science.gov (United States)

    Bartková, G; Ciznár, I; Lehotská, V; Kernová, T

    1994-01-01

    Escherichia coli was isolated from the urine of patients with pyelonephritis, with urinary tract infections other than pyelonephritis and with asymptomatic bacteriuria. Surface properties of the strains were analyzed by the salting-out aggregation test (SAT), hydrophobic interaction chromatography (HIC), Congo red binding (Crb), agglutination of erythrocytes (MRHA) and latex particles covered by digalactoside (PF) and by adherence to tissue culture cells. In addition, a DNA probe for the pap gene was used. The DNA probe detected the highest proportion of strains with pap gene in the group of patients with pyelonephritis, lower in the urinary tract infections other than pyelonephritis and the lowest in the group with asymptomatic bacteriuria. Tests for P-fimbriae (PF, MRHA) showed a similar distribution. Hydrophobicity measured by SAT and by HIC did not show differences among the tested groups of strains. The results suggest that factors other than the P-fimbriae and hydrophobicity may contribute to the persistence of E. coli in the urinary tract.

  4. Determining Engineering Properties of the Shallow Lunar Subsurface using Seismic Surface Wave Techniques

    Science.gov (United States)

    Yeluru, P. M.; Baker, G. S.

    2008-12-01

    The geology of Earth's moon has previously been examined via telescopic observations, orbiting spacecraft readings, lunar sample analysis, and also from some geophysical data. Previous researchers have examined layering of the moon and models exist explaining the velocity variations in the mantle and core. However, no studies (or datasets) currently exist regarding the engineering properties of the shallow (civil engineering works, as they characterize the mechanical behavior of geotechnical materials under various types of loading. Therefore, understanding the physical and engineering properties within the upper 30 m of the lunar subsurface will be critical for lunar exploration if deployment of large structures, large-scale excavation, and/or landing of large spacecraft on the surface is desired. Advances in near-surface geophysical techniques, such as Multi-channel Analysis of Surface Wave (MASW), has greatly increased our ability to map subsurface variations in physical properties. The MASW method involves deployment of multiple seismometers to acquire 1-D or 2-D shear wave velocity profiles that can be directly related to various engineering properties. The advantage of this technique over drilling boreholes or any other geophysical technique is that it is less intensive, non-invasive, more cost- effective, and more robust because strong surface-wave records are almost guaranteed. In addition, data processing and analysis is fairly straightforward, and the MASW method allows for analysis of a large area of interest as compared to drilling boreholes. A new scheme using randomly distributed geophones (likely deployed from a mortar-type device) instead of a conventional linear array will be presented. A random array is necessary for lunar exploration because of the logistical constraints involved in deploying a linear or circular array robotically or by astronaut. Initial results indicate that robust dispersion curves (and thus subsurface models of engineering

  5. Identifying dispersive GPR signals and inverting for surface waveguide properties

    Science.gov (United States)

    van der Kruk, Jan; Jacob, Rob; Steelman, Colby; Endres, Tony; Vereecken, Harry

    2010-05-01

    At locations where a thin surface layer overlies a substrate medium that has a lower permittivity, or a much larger permittivity/conductivity than the surface layer, pronounced dispersion of GPR waves can be observed and the surface layer acts as a waveguide. A low velocity waveguide is present when the substrate has a lower permittivity and total reflection occurs beyond the critical angle on the upper and lower interfaces. A leaky waveguide is present when the substrate medium has a much larger permittivity and/or conductivity. Although the lower interface is a strong reflector, some energy is still transmitted across the interface and total reflection only occurs at the upper waveguide-air interface. In both cases, electromagnetic waves are trapped within the waveguide and the radar energy is internally reflected, resulting in a series of interfering multiples that manifest themselves as shingling reflections that exhibit different phase and group velocities. Normalizing the data on the maximum amplitude for each trace shows that most of the energy is contained within the dispersive waves which propagate over large distances. Phase-velocity spectra calculated from these dispersed GPR data clearly indicate the presence of a frequency-dependent phase velocity that decreases with increasing frequency. The dispersion characteristics depend on the type of waveguide and the source-receiver antenna orientations. For low-velocity waveguides, the transverse electric (TE) modes propagate at lower frequencies compared to transverse magnetic (TM) modes, whereas only uneven TE and even TM modes can propagate through leaky waveguides. The waveguide properties can be obtained by picking dispersion curves from the maxima in the phase-velocity spectra and inverting for a single-layer waveguide model by adjusting the model parameters using a combined global and local minimization algorithm until the difference between the picked dispersion curve and the model-predicted dispersion

  6. 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

  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. Unique surface adsorption behaviors of serum proteins on chemically uniform and alternating surfaces

    Science.gov (United States)

    Song, Sheng

    With increasing interests of studying proteins adsorption on the surfaces with nanoscale features in biomedical field, it is crucial to have fundamental understandings on how the proteins are adsorbed on such a surface and what factors contribute to the driving forces of adsorption. Besides, exploring more available nanoscale templates would greatly offer more possibilities one could design surface bio-detection methods with favorable protein-surface interactions. Thus, to fulfill the purpose, the work in this dissertation has been made into three major sections. First, to probe the intermediate states which possibly exist between stable and unstable phases described in mean-field theory diagram, a solvent vapor annealing method is chosen to slowly induce the copolymer polystyrene-block-polyvinylpyridine (PS-b-PVP)'s both blocks undergoing micro-phase separations from initial spherical nanodomains into terminal cylindrical nanodomains. During this process, real time atomic force microscopy (AFM) has been conducted to capture other six intermediate states with different morphologies on the polymeric film surfaces. Secondly, upon recognizing each intermediate state, the solution of immunoglobulin gamma (IgG) proteins has been deposited on the surface and been rinsed off with buffer solution before the protein-bounded surface is imaged by AFM. It has been found IgG showing a strong adsorption preference on PS over P4VP block. Among all the six intermediate states, the proteins are almost exclusively adsorbed on PS nanodomains regardless the concentration and deposition time. Thirdly, a trinodular shape protein fibrinogen (Fg) is selected for investigating how geometry and surface charge of proteins would interplay with cylindrical nanodomains on a surface developed from Polystyrene -block-Poly-(methyl methacrylate) PS-b-PMMA. Also, Fg adsorptions on chemically homogeneous surfaces are included here to have a better contrast of showing how much difference it can make

  9. Structure and Optical Properties of thin Porous Anodic Alumina Films Synthesized on a Glass Surface

    Science.gov (United States)

    Valeev, R. G.; Petukhov, D. I.; Kriventsov, V. V.

    The structure and luminescent properties of thin nanoporous aluminum oxide films obtained by anodization of aluminum films thermally deposited on glass have been investigated. The pore size and the interpore distance depend on the anodization voltage. For all studied samples the highest emission intensity obtained at the excitation wavelength equal to 330 nm. This behavior of luminescence curves caused by defect F+ luminescent centers (O- oxygen vacancies). The presence of porous alumina films on the glass surface increases the optical absorption in the visible light region. The oscillations on the spectra are caused by Fabry-Perot interference on the anodic alumina oxide film/glass interface. The suggested technique can be used for obtaining porous aluminum oxide films on other substrates, including Indium-Tin-Oxide, and can be applied in the technology of light-emitting devices and infrared-visible-ultraviolet detectors.

  10. Molecular dynamics simulation of atomic-scale frictional behavior of corrugated nano-structured surfaces.

    Science.gov (United States)

    Kim, Hyun-Joon; Kim, Dae-Eun

    2012-07-01

    Surface morphology is one of the critical parameters that affect the frictional behavior of two contacting bodies in relative motion. It is important because the real contact area as well as the contact stiffness is dictated by the micro- and nano-scale geometry of the surface. In this regard, the frictional behavior may be controlled by varying the surface morphology through nano-structuring. In this study, molecular dynamics simulations were conducted to investigate the effects of contact area and structural stiffness of corrugated nano-structures on the fundamental frictional behavior at the atomic-scale. The nano-structured surface was modeled as an array of corrugated carbon atoms with a given periodicity. It was found that the friction coefficient of the nano-structured surface was lower than that of a smooth surface under specific contact conditions. The effect of applied load on the friction coefficient was dependent on the size of the corrugation. Furthermore, stiffness of the nano-structure was identified to be an important variable in dictating the frictional behavior.

  11. 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...

  12. 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.

  13. Solder wetting behavior enhancement via laser-textured surface microcosmic topography

    Science.gov (United States)

    Chen, Haiyan; Peng, Jianke; Fu, Li; Wang, Xincheng; Xie, Yan

    2016-04-01

    In order to reduce or even replace the use of Sn-Pb solder in electronics industry, the laser-textured surface microstructures were used to enhance the wetting behavior of lead free solder during soldering. According to wetting theory and Sn-Ag-Cu lead free solder performance, we calculated and designed four microcosmic structures with the similar shape and different sizes to control the wetting behavior of lead free solder. The micro-structured surfaces with different dimensions were processed on copper plates by fiber femtosecond laser, and the effect of microstructures on wetting behavior was verified experimentally. The results showed that the wetting angle of Sn-Ag-Cu solder on the copper plate with microstructures decreased effectively compared with that on the smooth copper plate. The wetting angles had a sound fit with the theoretical values calculated by wetting model. The novel method provided a feasible route for adjusting the wetting behavior of solders and optimizing solders system.

  14. Surface critical behavior of thin Ising films at the ‘special point’

    Science.gov (United States)

    Moussa, Najem; Bekhechi, Smaine

    2003-03-01

    The critical surface phenomena of a magnetic thin Ising film is studied using numerical Monte-Carlo method based on Wolff cluster algorithm. With varying the surface coupling, js= Js/ J, the phase diagram exhibits a special surface coupling jsp at which all the films have a unique critical temperature Tc for an arbitrary thickness n. In spite of this, the critical exponent of the surface magnetization at the special point is found to increase with n. Moreover, non-universal features as well as dimensionality crossover from two- to three-dimensional behavior are found at this point.

  15. New Possibilities of Shaping the Surface Properties in Austempered Ductile Iron Castings

    OpenAIRE

    D. Myszka

    2013-01-01

    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...

  16. Psychometric properties of a Dutch version of the Behavior Problems Inventory-01 (BPI-01)

    NARCIS (Netherlands)

    Dumont, E.L.M.; Kroes, D.B.H.; Korzilius, H.P.L.M.; Didden, H.C.M.; Rojahn, J.

    2014-01-01

    There are only a limited number of Dutch validated measurement instruments for measuring behavioral problems in people with a moderate to profound intellectual disability. In this study, the psychometric properties of a Dutch version of the behavior Problems Inventory-01 (BPI-01; Rojahn et al., 2001

  17. Flow and thermal behavior of the top surface flux/powder layers in continuous casting molds

    Science.gov (United States)

    McDavid, R. M.; Thomas, B. G.

    1996-08-01

    Steady-state finite-element models have been formulated to investigate the coupled fluid flow and thermal behavior of the top-surface flux layers in continuous casting of steel slabs. The three-dimensional (3-D) FIDAP model includes the shear stresses imposed on the flux/steel interface by flow velocities calculated in the molten steel pool. It also includes different temperature-dependent powder properties for solidification and melting. Good agreement between the 3-D model and experimental measurements was obtained. The shear forces, imposed by the steel surface motion toward the submerged entry nozzle (SEN), create a large recirculation zone in the liquid flux pool. Its depth increases with increasing casting speed, increasing liquid flux conductivity, and decreasing flux viscosity. For typical conditions, this zone contains almost 4 kg of flux, which contributes to an average residence time of about 2 minutes. Additionally, because the shear forces produced by the narrowface consumption and the steel flow oppose each other, the flow in the liquid flux layer separates at a location centered 200 mm from the narrowface wall. This flow separation depletes the liquid flux pool at this location and may contribute to generically poor feeding of the mold-strand gap there. As a further consequence, a relatively cold spot develops at the wideface mold wall near the separation point. This nonuniformity in the temperature distribution may result in nonuniform heat removal, and possibly nonuniform initial shell growth in the meniscus region along the wideface off-corner region. In this way, potential steel quality problems may be linked to flow in the liquid flux pool.

  18. 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.

  19. 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.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stoleru, Elena; Dumitriu, Raluca Petronela [Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley, 41A, 700487 Iasi (Romania); Munteanu, Bogdanel Silvestru [“Al. I. Cuza” University, Faculty of Physics, 11 Carol I Blvd., 700506 Iasi (Romania); Zaharescu, Traian [INCDIE ICPE CA, Bucharest (Romania); Tănase, Elisabeta Elena; Mitelut, Amalia [Industrial Biotechnology Department, Faculty of Biotechnology – USAMV Bucharest (Romania); Ailiesei, Gabriela-Liliana [Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley, 41A, 700487 Iasi (Romania); Vasile, Cornelia, E-mail: cvasile@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, Grigore Ghica Voda Alley, 41A, 700487 Iasi (Romania)

    2016-03-30

    Graphical abstract: - Highlights: • PLA requires functionalization prior to surface attaching chitosan. • Chitosan with different molecular weights was grafted onto PLA surface. • Antibacterial, antifungal, antioxidant PLA-based materials are obtained. • Nano-fibers coatings obtained by electrospinning of high molecular weight chitosan. - Abstract: 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.

  2. Unusual dynamic dewetting behavior of smooth perfluorinated hybrid films: potential advantages over conventional textured and liquid-infused perfluorinated surfaces.

    Science.gov (United States)

    Urata, Chihiro; Masheder, Benjamin; Cheng, Dalton F; Hozumi, Atsushi

    2013-10-08

    From a viewpoint of reducing the burden on the environment and human health, an alternative method for preparing liquid-repellent surfaces without relying on the long perfluorocarbons (C((X-1)/2)F(X), X ≥ 17) has been strongly demanded lately. In this study, we have successfully demonstrated that dynamic dewettability toward various probe liquids (polar and nonpolar liquids with high or low surface tension) can be tuned by not only controlling surface chemistries (surface energies) but also the physical (solid-like or liquid-like) nature of the surface. We prepared smooth and transparent organic-inorganic hybrid films exhibiting unusual dynamic dewetting behavior toward various probe liquids using a simple sol-gel reaction based on the co-hydrolysis and co-condensation of a mixture including a range of perfluoroalkylsilanes (FASX, C((X-1)/2)F(X)CH2CH2Si(OR)3, where X = 3, 9, 13, and 17) and tetramethoxysilane (Si(OCH3)4, TMOS). Dynamic contact angle (CA) and substrate tilt angle (TA) measurements confirmed that our FASX-hybrid films exhibited excellent dynamic dewetting properties and were mostly independent of the length of perfluoroalkyl (Rf) groups. For example, 10 μL droplets of ultralow surface tension liquids (e.g., diethyl ether (γ = 16.26 dyn/cm) and n-pentane (γ = 15.51 dyn/cm)) could move easily on our FAS9-, FAS13-, and FAS17-hybrid film surfaces at low substrate TAs (dynamic dewetting behavior appeared only when TMOS molecules were added to the precursor solutions; we assume this is due to co-condensed TMOS-derived silica species working as spacers between the neighboring Rf chains, enabling them to rotate freely and in doing so provide a surface with liquid-like properties. This led to the distinguished dynamic dewettability of our hybrid films, regardless of the small static CAs. Our FASX-hybrid films also displayed excellent chemical and physical durability against thermal stress (~250 °C), high-temperature (150 °C) oil vapor, and various

  3. Properties of pedestrians walking in line: Stepping behavior

    CERN Document Server

    Jelić, Asja; Lemercier, Samuel; Pettré, Julien

    2012-01-01

    In human crowds, interactions among individuals give rise to a variety of self-organized collective motions that help the group to effectively solve the problem of coordination. However, it is still not known how exactly are the humans adjusting their behavior locally, nor what are the direct consequences on the emergent organization. One of the underlying mechanisms of adjusting individual motions is the stepping dynamics. In this paper, we present first quantitative analysis on the stepping behavior in a one-dimensional pedestrian flow studied under controlled laboratory conditions. We find that the step length is proportional to the velocity of the pedestrian, and is directly related to the space available in front of him, while the variations of the step duration are much weaker. Furthermore, we study the phenomena of synchronization --walking in lock-steps-- and show its dependence on the flow densities. We show that the synchronization of steps is particularly important at high densities, which has dire...

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

    Science.gov (United States)

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

    2007-04-24

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

  5. 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.

  6. 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

  7. Effects of the surface-adsorption of boron-doped diamond electrode on its electrochemical behavior

    Institute of Scientific and Technical Information of China (English)

    LIU Fengbin; LI Xuemin; WANG Jiadao; LIU Bing; CHEN Darong

    2006-01-01

    To elucidate the effects of the hydro- genation and oxygenation of the boron-doped diamond (BDD) electrode on its electrochemical behaviors, the surface morphologies and phases of the two surface-adsorption BDD films have been investigated and the cyclic voltammograms and AC impedance spectra have been measured at these two BDD electrodes. The results indicate that compared with the hydrogen-adsorption BDD film, oxygen-adsor- ption BDD film is less conductive, and has a larger surface roughness and a lower sp3/sp2 ratio. The oxygenated BDD film electrode possesses a wider electrochemical window, larger diamond film resistance and capacitance and a larger polarization resistance than hydrogenated BDD electrode. In addition, the effect mechanism of the surface-adsorption of BDD electrode on its electrochemical behaviors has been discussed.

  8. Properties that influence the specific surface areas of carbon nanotubes and nanofibers.

    Science.gov (United States)

    Birch, M Eileen; Ruda-Eberenz, Toni A; Chai, Ming; Andrews, Ronnee; Hatfield, Randal L

    2013-11-01

    Commercially available carbon nanotubes and nanofibers were analyzed to examine possible relationships between their Brunauer-Emmett-Teller specific surface areas (SSAs) and their physical and chemical properties. Properties found to influence surface area were number of walls/diameter, impurities, and surface functionalization with hydroxyl and carboxyl groups. Characterization by electron microscopy, energy-dispersive X-ray spectrometry, thermogravimetric analysis, and elemental analysis indicates that SSA can provide insight on carbon nanomaterials properties, which can differ vastly depending on synthesis parameters and post-production treatments. In this study, how different properties may influence surface area is discussed. The materials examined have a wide range of surface areas. The measured surface areas differed from product specifications, to varying degrees, and between similar products. Findings emphasize the multiple factors that influence surface area and mark its utility in carbon nanomaterial characterization, a prerequisite to understanding their potential applications and toxicities. Implications for occupational monitoring are discussed.

  9. Method of Monitoring the Corrosion Behavior the Surface Treated FMS and CVD Coated Specimen in Liquid Sodium Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Hyeon; Shin, Sang Hun; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2014-10-15

    Gr.92 and HT9 (Ferritic/martensitic steels) are considered as candidates of cladding materials of Sodium-cooled Fast Reactors (SFRs). HT9 and Gr.92 are known as compatible in sodium environment because the usual refueling time of SFRs is designed about 54 months. 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. The decarburization process where dissolved carbon near the specimen surface diffused in to the liquid sodium. This process can originate from the difference between dissolved carbon activity in the material and liquid sodium. A compatibility test the cladding tube revealed that a decrease of the mechanical property instigated by the aging proves governed the whole mechanical property. SiC and Si3N4 Chemical Vapor Deposition (CVD) coating for decarburization barrier on the surface of FMS is considered in this study. The CVD coated specimens are experiment for compatibility of high temperature liquid sodium. To monitor the corrosion behavior of these candidate materials in sodium environment, Electrochemical Impedance Spectroscopy (EIS) method is first introduced and investigated in this study. The use of the technique of impedance spectroscopy to measure the electrical impedance response of any oxide layers, SiC and Si{sub 3}N{sub 4} that may be present may be a solution to this monitoring problem.

  10. Theoretical Modeling of Mechanical Behavior and Release Properties of Microcapsules

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2015-01-01

    Microcapsules in food often have a shell with a complex microstructure; the mechanical and structural properties of these shells affect the response of the capsules to deforming forces and the release kinetics of encapsulated components. In this chapter we will discuss a number of models which are t

  11. 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.

  12. Contact Angle Hysteresis on Graphene Surfaces and Hysteresis-free Behavior on Oil-infused Graphite Surfaces

    Science.gov (United States)

    Wu, Cyuan-Jhang; Li, Yueh-Feng; Woon, Wei-Yen; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2016-11-01

    Contact angle hysteresis (CAH) on graphitic surfaces, including chemical vapor deposition (CVD) graphene, reduced electrophoretic deposition (EPD) graphene, highly oriented pyrolytic graphite (HOPG), and polished graphite sheet, has been investigated. The hysteresis loops of water drops on the first three samples are similar but the receding contact angle is particularly small for the polished graphite sheet.The significant CAH observed on CVD graphene and HOPG associated with atom-scale roughness has to be attributed mainly to adhesion hysteresis (surface relaxation), instead of roughness or defects.The difference of the wetting behavior among those four graphitic samples has been further demonstrated by hexadecane drops. On the surface of HOPG or CVD graphene,the contact line expands continuously with time, indicating total wetting for which the contact angle does not exist and contact line pinning disappears. In contrast, on the surface of reduced EPD graphene, spontaneous spreading is halted by spikes on it and partial wetting with small contact angle (θ≈4°) is obtained. On the surface of polished graphite sheet, the superlipophilicity and porous structure are demonstrated by imbibition and capillary rise of hexadecane. Consequently, an oil-infused graphite surface can be fabricated and the ultralow CAH of water (∆θ≈2°) is achieved.

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

    OpenAIRE

    M. Zielińska; Kubiak, K.; J. Sieniawski

    2009-01-01

    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 diff...

  14. 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.

  15. Dynamic behavior of a vibrated droplet on a low-temperature micropillared surface

    Science.gov (United States)

    Tan, Chen-chuan; Jia, Zhi-hai; Yang, Hui-nan; Zhang, Zhi-tao

    2017-02-01

    The dynamic behavior of a vibrated droplet on a micropillared hydrophobic surface under low temperature was investigated in this paper. It was observed that solidified time of droplets on the micropillared surface were much larger than on the smooth surface due to the existence of wetting transition at low temperature, without vibration. The solidified time of droplets was longer while vibration was exerted on the surfaces, even though the wetting transition time of droplets at low temperature was shorter than at room temperature. It was found that resonance frequency of droplet increased as surface tension increased due to low temperature. Moreover, when a droplet was in its resonance frequency, the wetting area between the droplet and the micropillared surface increased obviously and its solidified time decreased substantially, and it led to the decline of anti-icing performance. This work is helpful to design a more efficient anti-icing device.

  16. 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

  17. Effect of droplet size on wetting behavior on laser textured SiC surface

    Science.gov (United States)

    Wang, Rong; Bai, Shaoxian

    2015-10-01

    Effect of droplet size on wetting behavior on laser textured SiC surface was studied in this work. The micro-square-convex surface was processed on smooth surface with intrisinc contact angle 101°. Then contact angles were measured on both smooth and textured surface by sessile drop method using deionized water with different droplet volume. It was found that there was significant droplet size effect on wetting behaviors for the textured SiC surface. Contact angles on smooth surface kept stable for different water droplet volume with a variation amplitude 13°. However, contact angles increased significantly from 42.25° to 131.25° with increasing droplet volume from 0.001 μL to 1 μL, then remained unchanged when the droplet volume exceeds 1 μL. The correlation analysis shows that contact angles increase with the increasing ratio of base diameter and groove width, then keep stable when the ratio exceeds 25, which explains the wetting behavior for different droplet volume.

  18. Functionalized titanium oxide surfaces with phosphated carboxymethyl cellulose: characterization and bonelike cell behavior.

    Science.gov (United States)

    Pasqui, Daniela; Rossi, Antonella; Di Cintio, Federica; Barbucci, Rolando

    2007-12-01

    The performance of dental or orthopedic implants is closely dependent on surface properties in terms of topography and chemistry. A phosphated carboxymethylcellulose containing one phosphate group for each disaccharide unit was synthesized and used to functionalize titanium oxide surfaces with the aim to improve osseointegration with the host tissue. The modified surfaces were chemically characterized by means of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The investigation of the surface topography was performed by atomic force microscopy measurements before and after the polysaccharide coating. In vitro biological tests using osteoblastlike cells demonstrated that functionalized TiO(2) surfaces modulated cell response, in terms of adhesion, proliferation,and morphology. Phosphated carboxymethylcellulose promoted better cell adhesion and significantly enhanced their proliferation. The morphology of cells was polygonal and more spread on this type of modified surface.These findings suggest that the presence of a phosphate polysaccharide coating promotes osteoblast growth on the surface potentially improving biomaterial osseointegration.

  19. Dynamic Behaviors and Energy Transition Mechanism of Droplets Impacting on Hydrophobic Surfaces

    Directory of Open Access Journals (Sweden)

    Qiaogao Huang

    2016-01-01

    Full Text Available The wettability of hydrophobic surfaces and the dynamic behaviors of droplets impacting on hydrophobic surfaces are simulated using a lattice Boltzmann method, and the condition for the rebound phenomenon of droplets impacting on solid surfaces is analyzed. The results show that there is a linear relationship between the intrinsic contact angle and the interaction strength of fluid-wall particles. For hydrophobic surfaces with the same intrinsic contact angle, the micromorphology can increase the surface hydrophobicity, especially the hierarchical micromorphology. The dynamic behaviors of droplets impacting on solid surfaces are affected by the wettability. The surface hydrophobicity is stronger, and the rebound phenomenon occurs easier. If the droplet’s kinetic energy is greater than the sum of the surface energy and the minimum conversion gravitational potential energy when the spreading and shrinking finish, the rebound phenomenon will occur. As the hydrophobic surface’s viscous dissipation is much smaller than the hydrophilic surface’s, the droplet still has high kinetic energy after the spreading and shrinking, which is advantageous to rebound for droplets.

  20. 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.

  1. Ultra-fast boriding of metal surfaces for improved properties

    Science.gov (United States)

    Timur, Servet; Kartal, Guldem; Eryilmaz, Osman L.; Erdemir, Ali

    2015-02-10

    A method of ultra-fast boriding of a metal surface. The method includes the step of providing a metal component, providing a molten electrolyte having boron components therein, providing an electrochemical boriding system including an induction furnace, operating the induction furnace to establish a high temperature for the molten electrolyte, and boriding the metal surface to achieve a boride layer on the metal surface.

  2. Elastic Properties of Liquid Surfaces Coated with Colloidal Particles

    Directory of Open Access Journals (Sweden)

    Edward Bormashenko

    2015-01-01

    Full Text Available The physical mechanism of elasticity of liquid surfaces coated with colloidal particles is proposed. It is suggested that particles are separated by water clearings and the capillary interaction between them is negligible. The case is treated when the colloidal layer is deformed normally to its surface. The elasticity arises as an interfacial effect. The effective Young modulus of a surface depends on the interfacial tension, equilibrium contact angle, radius of colloidal particles, and their surface density. For the nanometrically scaled particles the line tension becomes essential and has an influence on the effective Young modulus.

  3. Macroscopic behavior and microscopic magnetic properties of nanocarbon

    Energy Technology Data Exchange (ETDEWEB)

    Lähderanta, E., E-mail: Erkki.Lahderanta@lut.fi [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Ryzhov, V.A. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Coppice, Gatchina, Leningrad province 188300 (Russian Federation); Lashkul, A.V. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Galimov, D.M. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); South Ural State University, 454080 Chelyabinsk (Russian Federation); Titkov, A.N. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); A. F. Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Matveev, V.V. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Saint-Petersburg State University, Saint-Petersburg 198504 (Russian Federation); Mokeev, M.V. [Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg (Russian Federation); Kurbakov, A.I. [Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Coppice, Gatchina, Leningrad province 188300 (Russian Federation); Lisunov, K.G. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Institute of Applied Physics ASM, Academiei Str., 5, MD 2028 Kishinev (Moldova, Republic of)

    2015-06-01

    Here are presented investigations of powder and glass-like samples containing carbon nanoparticles, not intentionally doped and doped with Ag, Au and Co. The neutron diffraction study reveals an amorphous structure of the samples doped with Au and Co, as well as the magnetic scattering due to a long-range FM order in the Co-doped sample. The composition and molecular structure of the sample doped with Au is clarified with the NMR investigations. The temperature dependence of the magnetization, M (T), exhibits large irreversibility in low fields of B=1–7 mT. M (B) saturates already above 2 T at high temperatures, but deviates from the saturation behavior below ~50 (150 K). Magnetic hysteresis is observed already at 300 K and exhibits a power-law temperature decay of the coercive field, B{sub c} (T). The macroscopic behavior above is typical of an assembly of partially blocked magnetic nanoparticles. The values of the saturation magnetization, M{sub s}, and the blocking temperature, T{sub b}, are obtained as well. However, the hysteresis loop in the Co-doped sample differs from that in other samples, and the values of B{sub c} and M{sub s} are noticeably increased. - Highlights: • We have investigated powder and glassy samples with carbon nanoparticles. • They include an undoped sample and those doped with Ag, Au and Co. • Neutron diffraction study reveals amorphous structure of Au- and Co-doped samples. • Composition and molecular structure of Au-doped sample was investigated with NMR. • Magnetic behavior is typical of an assembly of partially blocked magnetic nanoparticles.

  4. 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.

  5. 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

  6. 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.

  7. Influence of Annealing Temperature on CZTS Thin Film Surface Properties

    Science.gov (United States)

    Feng, Wenmei; Han, Junfeng; Ge, Jun; Peng, Xianglin; Liu, Yunong; Jian, Yu; Yuan, Lin; Xiong, Xiaolu; Cha, Limei; Liao, Cheng

    2017-01-01

    In this work, copper zinc tin sulfide (CZTS) films were deposited by direct current sputtering and the samples were annealed in different oven-set temperatures and atmosphere (Ar and H2S). The surface evolution was investigated carefully by using scanning electron microscopy (SEM), Raman spectroscopy and x-ray photoelectron spectroscopy. The surface of the as-sputtered precursor contained little Cu and large amounts of Zn and Sn. The metallic precursor was continuous and compact without pinholes or cracks. With the increase of the temperature from room temperature to 250°C, Cu atoms diffused to the film surface to form Cu1- x S and covered other compounds. Some small platelets were smaller than 500 nm spreading randomly in the holes of the film surfaces. When the temperature reached 350°C, Zn and Sn atoms began to diffuse to the surface and react with S or Cu1- x S. At 400°C, SEM showed the melting of large particles and small particles with a size from 100 nm to 200 nm in the background of the film surface. Excess Zn segregated towards the surface regions and formed ZnS phase on the surface. In addition, the signal of sodium in the CZTS surface was observed above 400°C. At 600°C, a large amount of regular structures with clear edges and corners were observed in the film surface in SEM images. A clear recrystallized process on the surface was assumed from those observations.

  8. Is there an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors? Part II

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huajie, E-mail: wanghuajie972001@163.com; Sun Yuanyuan; Cao Ying, E-mail: caoying1130@sina.com; Wang Kui; Yang Lin [Henan Normal University, College of Chemistry and Environmental Science (China); Zhang Yidong; Zheng Zhi [Xuchang University, Institute of Surface Micro and Nano Materials (China)

    2012-05-15

    Although nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured surfaces, whether there is an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors is still controversial. In this study, porous aluminum oxide membranes with different pore sizes ranging from 25 to 120 nm were prepared by the anodic oxidation technique. The surface morphology, topography and wettability were analyzed by scanning electron microscope, atomic force microscope and water contact angle measurement, respectively. The results indicated that the synergistic action of the nano-topography structure and hydrophilic/hydrophobic properties resulted in a highest protein adsorption on the aluminum oxide membrane with 80 nm pore size. Additionally, the morphological, metabolic and cell counting methods showed that cells had different sensitivity to porous aluminum oxide membranes with different surface features. Furthermore, this sensitivity was cell type dependent. The optimal pore size of aluminum oxide membranes for cell growth was 80 nm for PC12 cells and 50 nm for NIH 3T3 cells.

  9. Exploring Caregiver Behavior and Knowledge about Unsafe Sleep Surfaces in Infant Injury Death Cases

    Science.gov (United States)

    Chu, Tracy; Hackett, Martine; Kaur, Navpreet

    2015-01-01

    Objectives: In the United States, infant deaths due to sleep-related injuries have quadrupled over the past two decades. One of the major risk factors is the placement of an infant to sleep on a surface other than a crib or bassinet. This study examines contextual circumstances and knowledge and behaviors that may contribute to the placement of…

  10. 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 fi...

  11. 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.

  12. Factors affecting surface and release properties of thin PDMS films

    DEFF Research Database (Denmark)

    Vudayagiri, Sindhu; Junker, Michael Daniel; Skov, Anne Ladegaard

    2013-01-01

    of perfluoroether allylamide (PFE) lowered the surface energy which could ease the release. This is further investigated together with an evaluation of the resulting change in actuator performance. The relationship between the adhesive energy, surface energy, Young’s modulus and peel force of the films is analyzed....

  13. The influence of surface effect on vibration behaviors of carbon nanotubes under initial stress

    Science.gov (United States)

    Chen, X.; Fang, C. Q.; Wang, X.

    2017-01-01

    An analytical method is presented to solve the influence of surface effect on non-coaxial resonance of multi-walled carbon nanotubes embedded in matrix utilizing laminated structures model. Due to coupled van der Waals forces between adjacent tubes and surface effect exerted carbon nanotubes, the resonance frequencies and amplitude ratios of multi-walled carbon nanotubes under initial stresses show that the resonant characteristics of the multi-walled carbon nanotubes become complex and the numbers of vibrational modes do not keep increase under identical conditions after considering surface effects. The result obtained can be used as a beneficial reference for investigating the electronic and physical behaviors of carbon nanotubes.

  14. Radiative properties of materials with surface scattering or volume scattering: A review

    Institute of Scientific and Technical Information of China (English)

    Qunzhi ZHU; Hyunjin LEE; Zhuomin M. ZHANG

    2009-01-01

    Radiative properties of rough surfaces, parti-culate media and porous materials are important in thermal engineering and many other applications. These properties are often needed for calculating heat transfer between surfaces and volume elements in participating media, as well as for accurate radiometric temperature measure-ments. In this paper, recent research on scattering of thermal radiation by rough surfaces, fibrous insulation, soot, aerogel, biological materials, and polytetrafluor-oethylene (PTFE) is reviewed. Both theoretical modeling and experimental investigation are discussed. Rigorous solutions and approximation methods for surface scattering and volume scattering are described. The approach of using measured surface roughness statistics in Monte Carlo simulations to predict radiative properties of rough surfaces is emphasized. The effects of various parameters on the radiative properties of particulate media and porous materials are summarized.

  15. Biochar production from coffee residues: Optimization of surface characteristics and sorptive behavior

    Science.gov (United States)

    Fotopoulou, Kalliopi; Manariotis, Ioannis D.; Karapanagioti, Hrissi K.

    2015-04-01

    Biochar with high surface area is a promising sorbent for environmental remediation and is produced by heating biomass in an oxygen-limited environment. Knowing the surface characteristics increases our understanding of biochar interactions with pollutants. The hypothesis of the present study is that by controlling pyrolysis conditions, the surface characteristics and subsequently the sorption behavior of produced biochars can be optimized. Coffee residues were dried overnight at 50oC and then pyrolized into a gradient furnace at 850oC. Different solid/oxygen ratios during pyrolysis were tested as well as the up scaling of the process. The biochars produced were systematically characterized for their surface characteristics such as BET surface area, open surface area, pore and micropore volume, and average pore size. The effect of pyrolysis on the biochar suspension pH was examined with the mass addition technique that involves the addition of increasing amounts of the biochar to bottles containing 0.1 M NaNO3. FTIR analysis was used in order to determine the functional groups of the coffee residue and of the biochars. The macrostructure of the biochars was visualized by Scanning Electron Microscopy (SEM). Total Carbon (TC) in the samples was determined by Carlo Erba Elemental Analyzer CHNS, EO 1108 after calibration with standard samples. The sorption behavior of produced biochars was tested with two different pollutants (Hg(II), phenanthrene) using batch reactors with the same initial single-compound solution and the same mass of coffee residue and different biochars. The biochars produced exhibited a wide range of surface area from 21 to 770 m2/g and open surface area due to macropores from 21 to 65 m2/g. This suggests that the surface area in the biochars with high surface area results from the formation of pores. Actually for the biochar with the highest surface area, it was calculated that up to 90

  16. 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

  17. The surface properties of carbon fibers and their adhesion to organic polymers

    Science.gov (United States)

    Bascom, W. D.; Drzal, L. T.

    1987-01-01

    The state of knowledge of the surface properties of carbon fibers is reviewed, with emphasis on fiber/matrix adhesion in carbon fiber reinforced plastics. Subjects treated include carbon fiber structure and chemistry, techniques for the study of the fiber surface, polymer/fiber bond strength and its measurement, variations in polymer properties in the interphase, and the influence of fiber matrix adhesion on composite mechanical properties. Critical issues are summarized and search recommendations are made.

  18. Patterns and scaling properties of surface soil moisture in an agricultural landscape: An ecohydrological modeling study

    Science.gov (United States)

    Korres, W.; Reichenau, T. G.; Schneider, K.

    2013-08-01

    Soil moisture is a key variable in hydrology, meteorology and agriculture. Soil moisture, and surface soil moisture in particular, is highly variable in space and time. Its spatial and temporal patterns in agricultural landscapes are affected by multiple natural (precipitation, soil, topography, etc.) and agro-economic (soil management, fertilization, etc.) factors, making it difficult to identify unequivocal cause and effect relationships between soil moisture and its driving variables. The goal of this study is to characterize and analyze the spatial and temporal patterns of surface soil moisture (top 20 cm) in an intensively used agricultural landscape (1100 km2 northern part of the Rur catchment, Western Germany) and to determine the dominant factors and underlying processes controlling these patterns. A second goal is to analyze the scaling behavior of surface soil moisture patterns in order to investigate how spatial scale affects spatial patterns. To achieve these goals, a dynamically coupled, process-based and spatially distributed ecohydrological model was used to analyze the key processes as well as their interactions and feedbacks. The model was validated for two growing seasons for the three main crops in the investigation area: Winter wheat, sugar beet, and maize. This yielded RMSE values for surface soil moisture between 1.8 and 7.8 vol.% and average RMSE values for all three crops of 0.27 kg m-2 for total aboveground biomass and 0.93 for green LAI. Large deviations of measured and modeled soil moisture can be explained by a change of the infiltration properties towards the end of the growing season, especially in maize fields. The validated model was used to generate daily surface soil moisture maps, serving as a basis for an autocorrelation analysis of spatial patterns and scale. Outside of the growing season, surface soil moisture patterns at all spatial scales depend mainly upon soil properties. Within the main growing season, larger scale

  19. Manipulation of fluids in three-dimensional porous photonic structures with patterned surface properties

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Effect of Direct Electric Current on the Cell Surface Properties of Phenol-Degrading Bacteria

    OpenAIRE

    Luo, Qishi; Wang, Hui; Zhang, Xihui; Qian, Yi

    2005-01-01

    The change in cell surface properties in the presence of electric currents is of critical concern when the potential to manipulate bacterial movement with electric fields is evaluated. In this study, the effects of different direct electric currents on the cell surface properties involved in bacterial adhesion were investigated by using a mixed phenol-degrading bacterial culture in the exponential growth phase. The traits investigated were surface hydrophobicity (measured by adherence to n-oc...

  1. On the Convergence of the Electronic Structure Properties of the FCC Americium (001) Surface

    OpenAIRE

    Gao, Da; Ray, Asok K.

    2006-01-01

    Electronic and magnetic properties of the fcc Americium (001) surface have been investigated via full-potential all-electron density-functional electronic structure calculations at both scalar and fully relativistic levels. Effects of various theoretical approximations on the fcc Am (001) surface properties have been thoroughly examined. The ground state of fcc Am (001) surface is found to be anti-ferromagnetic with spin-orbit coupling included (AFM-SO). At the ground state, the magnetic mome...

  2. Geotechnical properties of surface sediments in the INDEX area

    Digital Repository Service at National Institute of Oceanography (India)

    Khadge, N.H.

    ,natural water content,specific gravity,wet bulk density,and poros- ity were determined to learn the behavior of the deep-sea sediments from the nodule-bearingarea of the CIB. The sediments were siliceous in nature and showed variation in the parame-ters within... remained almost the same. The sedimentsstudied might have lower values for the parameters described here than those expected in situ.Therefore,even though these data do reveal good information on sediment behavior of the CIB,in situ and continuous...

  3. Surface supramolecular organization of a terbium(III) double-decker complex on graphite and its single molecule magnet behavior.

    Science.gov (United States)

    Gonidec, Mathieu; Biagi, Roberto; Corradini, Valdis; Moro, Fabrizio; De Renzi, Valentina; del Pennino, Umberto; Summa, Domenico; Muccioli, Luca; Zannoni, Claudio; Amabilino, David B; Veciana, Jaume

    2011-05-01

    The two-dimensional self-assembly of a terbium(III) double-decker phthalocyanine on highly oriented pyrolitic graphite (HOPG) was studied by atomic force microscopy (AFM), and it was shown that it forms highly regular rectangular two-dimensional nanocrystals on the surface, that are aligned with the graphite symmetry axes, in which the molecules are organized in a rectangular lattice as shown by scanning tunneling microscopy. Molecular dynamics simulations were run in order to model the behavior of a collection of the double-decker complexes on HOPG. The results were in excellent agreement with the experiment, showing that-after diffusion on the graphite surface-the molecules self-assemble into nanoscopic islands which align preferentially along the three main graphite axes. These low dimension assemblies of independent magnetic centers are only one molecule thick (as shown by AFM) and are therefore very interesting nanoscopic magnetic objects, in which all of the molecules are in interaction with the graphite substrate and might therefore be affected by it. The magnetic properties of these self-assembled bar-shaped islands on HOPG were studied by X-ray magnetic circular dichroism, confirming that the compounds maintain their properties as single-molecule magnets when they are in close interaction with the graphite surface.

  4. Unusual optical properties of graphene on an Rh surface

    Science.gov (United States)

    Rut'kov, E. V.; Gall, N. R.

    2015-01-01

    Single- and multilayer graphene films formed on the surface of a number of metals (Rh, Pt, Ir, and Re) at the thermal decomposition of benzene molecules have been studied. A surprising phenomenon has been revealed: these films with thicknesses up to 15 layers do not absorb light emitted by the surface and affect neither brightness nor true temperatures of the surface, which contradicts the fundamental results obtained by A. Geim and K. Novoselov. At larger thicknesses, absorption occurs in agreement with the commonly accepted concepts.

  5. Electronic and structural properties of the (1010) and (1120) ZnO surfaces.

    Science.gov (United States)

    Marana, N L; Longo, V M; Longo, E; Martins, J B L; Sambrano, J R

    2008-09-25

    The structural and electronic properties of ZnO (1010) and (1120) surfaces were investigated by means of density functional theory applied to periodic calculations at B3LYP level. The stability and relaxation effects for both surfaces were analyzed. The electronic and energy band properties were discussed on the basis of band structure as well as density of states. There is a significant relaxation in the (1010) as compared to the (1120) terminated surfaces. The calculated direct gap is 3.09, 2.85, and 3.09 eV for bulk, (1010), and (1120) surfaces, respectively. The band structures for both surfaces are very similar.

  6. 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.

  7. Analysis of local properties during a scratch test on a polymeric surface using molecular dynamics simulations.

    Science.gov (United States)

    Solar, M; Meyer, H; Gauthier, C

    2013-03-01

    This work demonstrates a possible route to connect a particle (chain) based understanding with continuum mechanical questions about contact mechanics. The bond orientation, chain conformation and stress field of a polymer film were analyzed during scratch tests (tangential contact) using a molecular dynamics (MD) simulation approach. Scratch tests with a conical tip at constant scratching velocity were simulated on linear amorphous polymer surfaces at various temperatures and roughnesses of the tip and for various interactions between the tip and the particles of the polymer chains. The second Legendre polynomial (computed for small domains around the tip) gave the bond orientation inside the polymer film during sliding of the tip. The gyration tensor (layer-resolved in the direction of the polymer film thickness) provided information about the conformation of the polymer chains. These results allowed us to argue in favor of Briscoe's hypothesis (thin film sheared vs. "bulk" compressive behavior) concerning the friction properties of the polymer surfaces. Finally, the first stress measurements of the virial stress tensor (in sub-boxes placed in the MD cell) revealed a complex combination between compressive hydrostatic pressure and shear stress, which may be interpreted as a complex sheared domain at the interface.

  8. 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.

  9. Behavior of GaSb (100) and InSb (100) surfaces in the presence of H2O2 in acidic and basic cleaning solutions

    Science.gov (United States)

    Seo, Dongwan; Na, Jihoon; Lee, Seunghyo; Lim, Sangwoo

    2017-03-01

    Gallium antimonide (GaSb) and indium antimonide (InSb) have attracted strong attention as new channel materials for transistors due to their excellent electrical properties and lattice matches with various group III-V compound semiconductors. In this study, the surface behavior of GaSb (100) and InSb (100) was investigated and compared in hydrochloric acid/hydrogen peroxide mixture (HPM) and ammonium hydroxide/hydrogen peroxide mixture (APM) solutions. In the acidic HPM solution, surface oxidation was greater and the etching rates of the GaSb and InSb surfaces increased when the solution is concentrated, which indicates that H2O2 plays a key role in the surface oxidation of GaSb and InSb in acidic HPM solution. However, the GaSb and InSb surfaces were hardly oxidized in basic APM solution in the presence of H2O2 because gallium and indium are in the thermodynamically stable forms of H2GaO3- and InO2-, respectively. When the APM solution was diluted, however, the Ga on the GaSb surface was oxidized by H2O, increasing the etching rate. However, the effect of dilution of the APM solution on the oxidation of the InSb surface was minimal; thus, the InSb surface was less oxidized than the GaSb surface and the change in the etching rate of InSb with dilution of the APM solution was not significant. Additionally, the oxidation behavior of gallium and indium was more sensitive to the composition of the HPM and APM solutions than that of antimony. Therefore, the surface properties and etching characteristics of GaSb and InSb in HPM and APM solutions are mainly dependent on the behavior of the group III elements rather than the group V elements.

  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. Low energy high current pulsed electron beam treatment for improving surface microstructure and properties

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J; Allain-Bonasso, N; Zhang, X D; Hao, S Z; Grosdider, T; Dong, C [Laboratoire d' Etude des Textures et Applications aux Materiaux (LETAM, UMR-CNRS 3143), Universite Paul Verlaine-Metz, Ile du Saulcy, 57045 Metz (France); Zou, J X, E-mail: jiang.wu@univ-metz.fr, E-mail: thierry.grosdidier@univ-metz.fr [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2010-06-15

    Low energy high current pulsed electron beam (LEHCPEB) is a fairly new technique for surface modifications authorizing improvement in wear and corrosion properties as well as texture changes and hardening. This contribution highlights some microstructure modifications encountered at the surface of HCPEB treated steels and bulk metallic glasses taking into account the effects of surface melting and the effects of the induced stress.

  12. Characterization of surface properties of a solid plate using nonlinear Lamb wave approach.

    Science.gov (United States)

    Deng, Mingxi

    2006-12-22

    A nonlinear Lamb wave approach is presented for characterizing the surface properties of a solid plate. This characterization approach is useful for some practical situations where ultrasonic transducers cannot touch the surfaces to be inspected, e.g. the inside surfaces of sealed vessels. In this paper, the influences of changes in the surface properties of a solid plate on the effect of second-harmonic generation by Lamb wave propagation were analyzed. A surface coating with the different properties was used to simulate changes in the surface properties of a solid plate. When the areas and thicknesses of coatings on the surface of a given solid plate changed, the amplitude-frequency curves both of the fundamental waves and the second harmonics by Lamb wave propagation were measured under the condition that Lamb waves had a strong nonlinearity. It was found that changes in the surface properties might clearly affect the efficiency of second-harmonic generation by Lamb wave propagation. The Stress Wave Factors (SWFs) in acousto-ultrasonic technique were used for reference, and the definitions of the SWFs of Lamb waves were introduced. The preliminary experimental results showed that the second-harmonic SWF of Lamb wave propagation could effectively be used to characterize changes in the surface properties of the given solid plate.

  13. Nonlinear Surface Dilatational Rheology and Foaming Behavior of Protein and Protein Fibrillar Aggregates in the Presence of Natural Surfactant.

    Science.gov (United States)

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

    2016-04-19

    The surface and foaming properties of native soy glycinin (11S) and its heat-induced fibrillar aggregates, in the presence of natural surfactant steviol glycoside (STE), were investigated and compared at pH 7.0 to determine the impact of protein structure modification on protein-surfactant interfacial interactions. The adsorption at, and nonlinear dilatational rheological behavior of, the air-water interface were studied by combining drop shape analysis tensiometry, ellipsometry, and large-amplitude oscillatory dilatational rheology. Lissajous plots of surface pressure versus deformation were used to analyze the surface rheological response in terms of interfacial microstructure. The heat treatment generates a mixture of long fibrils and unconverted peptides. The presence of small peptides in 11S fibril samples resulted in a faster adsorption kinetics than that of native 11S. The addition of STE affected the adsorption of 11S significantly, whereas no apparent effect on the adsorption of the 11S fibril-peptide system was observed. The rheological response of interfaces stabilized by 11S-STE mixtures also differed significantly from the response for 11S fibril-peptide-STE mixtures. For 11S, the STE reduces the degree of strain hardening in extension and increases strain hardening in compression, suggesting the interfacial structure may change from a surface gel to a mixed phase of protein patches and STE domains. The foams generated from the mixtures displayed comparable foam stability to that of pure 11S. For 11S fibril-peptide mixtures STE only significantly affects the response in extension, where the degree of strain softening is decreased compared to the pure fibril-peptide system. The foam stability of the fibril-peptide system was significantly reduced by STE. These findings indicate that fibrillization of globular proteins could be a potential strategy to modify the complex surface and foaming behaviors of protein-surfactant mixtures.

  14. 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°.

  15. 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.

  16. Surface properties of new virginiamycin M(1) derivatives.

    Science.gov (United States)

    Nott, Katherine; Paquot, Michel; Dufour, Samuel; Eeman, Marc; Deleu, Magali

    2009-03-01

    Three kinds of derivatives of the M(1) factor of virginiamycin have been synthesised: esters with long chain fatty acids, oximes with modified polar amino acids and bis-derivatives with both the ester and oxime function. The study of the surface tension time dependence of M(1) and its derivatives has shown that it is necessary to enhance simultaneously the hydrophobicity and the hydrophilicity of M(1) to render M(1) surface-active. A structure/function relationship study of the surface-active bis-derivatives has shown that enhancing the hydrophobicity of the molecule led to slower adsorption kinetics, higher stability of the monolayers formed and a better capacity to penetrate a membrane model. The repulsive electrostatic forces due to the presence of charges on the amino acids linked to M(1) lead to higher surface tensions, a greater molecular area at the interface and lower penetration into a membrane model. This study has demonstrated that modifying systematically the hydrophobicity and hydrophilicity of a non surface-active molecule allows the production of surface-active derivatives.

  17. Antifouling property of highly oleophobic substrates for solar cell surfaces

    Science.gov (United States)

    Fukada, Kenta; Nishizawa, Shingo; Shiratori, Seimei

    2014-03-01

    Reduction of solar cell conversion efficiency by bird spoor or oil smoke is a common issue. Maintaining the surface of solar cells clean to retain the incident light is of utmost importance. In this respect, there has been growing interest in the area of superhydrophobicity for developing water repelling and self-cleaning surfaces. This effect is inspired by lotus leaves that have micro papillae covered with hydrophobic wax nanostructures. Superhydrophobic surfaces on transparent substrates have been developed for removing contaminants from solar cell surfaces. However, oil cannot be removed by superhydrophobic effect. In contrast, to prevent bird spoor, a highly oleophobic surface is required. In a previous study, we reported transparent-type fabrics comprising nanoparticles with a nano/micro hierarchical structure that ensured both oleophobicity and transparency. In the current study, we developed new highly oleophobic stripes that were constructed into semi-transparent oleophobic surfaces for solar cells. Solar cell performance was successfully maintained; the total transmittance was a key factor for determining conversion efficiency.

  18. Relaxor behavior and electrical properties of high dielectric constant materials

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism. It is found that a Lorenz-type law can be used to describe the dielectric permit- tivity of either the normal ferroelectrics with or without diffuse phase transitions (DPT) or the typical ferroelectric relaxors. The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law, while the relaxor ferroelectric transition needs two independent fitting processes. The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition. Above the transition temperature, the dielectric curves of all the studied materials can be well described by a Lorenz-type law.

  19. Relaxor behavior and electrical properties of high dielectric constant materials

    Institute of Scientific and Technical Information of China (English)

    FAN HuiQing; KE ShanMing

    2009-01-01

    Several typical high dielectric constant materials are reviewed to study the electrical properties and relaxation mechanism.It is found that a Lorenz-type law can be used to describe the dielectric permitUvity of either the normal ferroelectrics with or without diffuse phase transitions(DPT)or the typical ferroelectric relaxors.The ferroelectric DPT can be well described by just one fitting process using the Lorenz-type law,while the relaxor ferroelectric transition needs two independent fitting processes.The Lorenz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition.Above the transition temperature,the dielectric curves of all the studied materials can be well described by a Lorenz-type law.

  20. The effects of deposition time on surface morphology, structural, electrical and optical properties of sputtered Ag-Cu thin films

    Science.gov (United States)

    Ahmadpourian, Azin; Luna, Carlos; Boochani, Arash; Arman, Ali; Achour, Amine; Rezaee, Sahare; Naderi, Sirvan

    2016-10-01

    The preparation of designed nanostructured thin films combining nano grains of different compositions and physical properties represents a promising avenue for the exploration of novel collective behaviors with technological potentials. Herein, nanostructured Ag-Cu thin films with different surface morphology properties were grown by magnetron sputtering varying the deposition time (4-24 min) and fixing the other deposition conditions. X-ray diffraction studies corroborated that Cu and Ag tend to appear as separated phases with nanometric sizes due to the fact that these elements are rather immiscible. The deposited Cu tended to be partially oxidized with crystal sizes of several tens of nm, whereas the deposited Ag phase displayed a poor crystallinity with an average crystal size of around 3nm. However, at deposition time of few minutes, the formation of Ag-Cu crystals with a preferable crystallization orientation along the [111] direction was detected. The surface morphology of the obtained thin films was studied by atomic force microscopy determining the surface roughness and average particle sizes of the samples. These parameters were correlated with the plasmon resonance extinction bands of the different Ag-Cu films and their electrical properties, providing a reproducible route to obtain thin films with tuned electrical resistances and optical properties.

  1. 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.

  2. 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.

  3. Mechanical properties and failure behavior of unidirectional porous ceramics.

    Science.gov (United States)

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

    2016-04-14

    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.

  4. Behavioral and neural properties of social reinforcement learning.

    Science.gov (United States)

    Jones, Rebecca M; Somerville, Leah H; Li, Jian; Ruberry, Erika J; Libby, Victoria; Glover, Gary; Voss, Henning U; Ballon, Douglas J; Casey, B J

    2011-09-14

    Social learning is critical for engaging in complex interactions with other individuals. Learning from positive social exchanges, such as acceptance from peers, may be similar to basic reinforcement learning. We formally test this hypothesis by developing a novel paradigm that is based on work in nonhuman primates and human imaging studies of reinforcement learning. The probability of receiving positive social reinforcement from three distinct peers was parametrically manipulated while brain activity was recorded in healthy adults using event-related functional magnetic resonance imaging. Over the course of the experiment, participants responded more quickly to faces of peers who provided more frequent positive social reinforcement, and rated them as more likeable. Modeling trial-by-trial learning showed ventral striatum and orbital frontal cortex activity correlated positively with forming expectations about receiving social reinforcement. Rostral anterior cingulate cortex activity tracked positively with modulations of expected value of the cues (peers). Together, the findings across three levels of analysis--social preferences, response latencies, and modeling neural responses--are consistent with reinforcement learning theory and nonhuman primate electrophysiological studies of reward. This work highlights the fundamental influence of acceptance by one's peers in altering subsequent behavior.

  5. Hydrophobic silver nanoparticles trapped in lipid bilayers: Size distribution, bilayer phase behavior, and optical properties

    Directory of Open Access Journals (Sweden)

    Bothun Geoffrey D

    2008-11-01

    Full Text Available Abstract Background Lipid-based dispersion of nanoparticles provides a biologically inspired route to designing therapeutic agents and a means of reducing nanoparticle toxicity. Little is currently known on how the presence of nanoparticles influences lipid vesicle stability and bilayer phase behavior. In this work, the formation of aqueous lipid/nanoparticle assemblies (LNAs consisting of hydrophobic silver-decanethiol particles (5.7 ± 1.8 nm embedded within 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC bilayers is demonstrated as a function of the DPPC/Ag nanoparticle (AgNP ratio. The effect of nanoparticle loading on the size distribution, bilayer phase behavior, and bilayer fluidity is determined. Concomitantly, the effect of bilayer incorporation on the optical properties of the AgNPs is also examined. Results The dispersions were stable at 50°C where the bilayers existed in a liquid crystalline state, but phase separated at 25°C where the bilayers were in a gel state, consistent with vesicle aggregation below the lipid melting temperature. Formation of bilayer-embedded nanoparticles was confirmed by differential scanning calorimetry and fluorescence anisotropy, where increasing nanoparticle concentration suppressed the lipid pretransition temperature, reduced the melting temperature, and disrupted gel phase bilayers. The characteristic surface plasmon resonance (SPR wavelength of the embedded nanoparticles was independent of the bilayer phase; however, the SPR absorbance was dependent on vesicle aggregation. Conclusion These results suggest that lipid bilayers can distort to accommodate large hydrophobic nanoparticles, relative to the thickness of the bilayer, and may provide insight into nanoparticle/biomembrane interactions and the design of multifunctional liposomal carriers.

  6. 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.

  7. 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

  8. Enhanced slippery behavior and stability of lubricating fluid infused nanostructured surfaces

    Science.gov (United States)

    Pant, Reeta; Ujjain, Sanjeev Kumar; Nagarajan, Arun Kumar; Khare, Krishnacharya

    2016-07-01

    Stability of lubricating fluid infused slippery surfaces is a concern for scientists and engineers and attempts are being made for its improvement. Lubricating oil coated slippery surface for aqueous drops is one of the important candidates in this class and their stability needs be improved to make them useful for practical applications. Cloaking of water drops with thin lubricant layer results in the loss of lubricant leading to deterioration of slippery behavior. Surface roughness or porosity provides larger surface area to the lubricating fluid and would to affect the stability of the lubricating film. Here we report the effect of surface roughness, from tens of nanometer to few microns, on the stability of slippery surface. Samples with small nanoscale roughness show improved performance in terms of contact angle hysteresis, critical tilt angle and slip velocity. Whereas large roughness samples show poorer performance compared to small nanoscale roughness and smooth samples. Small nanoscale roughness samples also show relatively slower deterioration against loss of lubricant during water flow. Once completely lost, the slippery behavior can be restored again simply by coating the sample again by the lubricating fluid.

  9. 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

  10. Properties of Surface Film on X70 Pipeline Steel in CO32-/HCO3- Environment

    Institute of Scientific and Technical Information of China (English)

    胡钢; 许淳淳

    2005-01-01

    The electrochemical behavior of X70 pipeline steel in (0.5 mol·L-1 Na2CO3+lmol·L-1 NaHCO3) solution was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze the composition and microstructure of the surface film. The results showed that there were two anodic peaks at -600 mV and -350 inV.The surface film formed at -600 mV mainly consisted of ferrous carbonates and ferrous hydroxycarbonates. It had a small reaction resistance. It was metastable and possessed poor protective property. Numerous pits and microcracks existed on the film, which could be the active paths for the initiation of stress corrosion cracking. The surface film formed at -350 mV, mainly consisted of ferric oxides. It has high reaction resistance and offered good protection for the substrate.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fal-Miyar, V. [Dpto. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007, Oviedo (Spain); Cerdeira, M.A. [Dpto. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007, Oviedo (Spain); Garcia, J.A. [Dpto. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007, Oviedo (Spain)]. E-mail: joseagd@uniovi.es; Tejedor, M. [Dpto. de Fisica, Universidad de Oviedo, c/ Calvo Sotelo s/n, 33007, Oviedo (Spain); Potatov, A.P. [Institute of Metal Physics, U.D. RAS, Kavalevskaya Str. 18 GSP-170 Ekaterinburg (Russian Federation); Pierna, A.R. [Dpto. de Ingenieria Quimica y Medio Ambiente, Universidad del Pais Vasco, PO Box 1379, 20080 San Sebastian (Spain); Marzo, F.F. [Dpto. de Ingenieria Quimica y Medio Ambiente, Universidad del Pais Vasco, PO Box 1379, 20080 San Sebastian (Spain); Vara, G. [Dpto. de Ingenieria Quimica y Medio Ambiente, Universidad del Pais Vasco, PO Box 1379, 20080 San Sebastian (Spain)

    2007-09-15

    In this paper the result of a study of the influence of the biological conditions on the surface magnetic properties of nanocrystalline Co{sub 64.5}Fe{sub 2.5}Cr{sub 3}B{sub 15}Si{sub 15} 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.

  12. 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.

  13. 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...

  14. Surface properties of liquid In-Zn alloys

    Science.gov (United States)

    Pstruś, J.; Moser, Z.; Gąsior, W.

    2011-02-01

    The measurements of surface tension and density of zinc, indium and liquid In-Zn alloys containing 0.9, 0.85, 0.75, 0.70, 0.60, 0.40, 0.25 and 0.10 mole fraction of In were carried out using the method of maximum pressure in gaseous bubbles (MBP) as well as dilatometric technique. The technique of sessile drop was additionally applied in the measurements of surface tension for pure indium and zinc. The measurements were performed at temperature range 474-1151 K. The isotherms of surface tension calculated based on Butler's equation at 700 and 1100 K corresponded well with the experimental values for zinc content lower than 0.6 mole fraction. The surface tension calculated for alloys of higher zinc concentrations (0.6 < XZn < 0.95) had a positive value of the surface tension temperature coefficient (dσ/dT), which did not coincide with the experimental results. The density as well as molar volume of liquid In-Zn alloys showed almost identical behaviour like the ideal solutions. The observed little deviations were contained within assessed experimental errors.

  15. Surface properties of liquid In-Zn alloys

    Energy Technology Data Exchange (ETDEWEB)

    Pstrus, J., E-mail: nmpstrus@imim-pan.krakow.pl [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Krakow (Poland); Moser, Z.; Gasior, W. [Institute of Metallurgy and Materials Science, Polish Academy of Sciences, 25 Reymonta Str., 30-059 Krakow (Poland)

    2011-02-15

    The measurements of surface tension and density of zinc, indium and liquid In-Zn alloys containing 0.9, 0.85, 0.75, 0.70, 0.60, 0.40, 0.25 and 0.10 mole fraction of In were carried out using the method of maximum pressure in gaseous bubbles (MBP) as well as dilatometric technique. The technique of sessile drop was additionally applied in the measurements of surface tension for pure indium and zinc. The measurements were performed at temperature range 474-1151 K. The isotherms of surface tension calculated based on Butler's equation at 700 and 1100 K corresponded well with the experimental values for zinc content lower than 0.6 mole fraction. The surface tension calculated for alloys of higher zinc concentrations (0.6 < X{sub Zn} < 0.95) had a positive value of the surface tension temperature coefficient (d{sigma}/dT), which did not coincide with the experimental results. The density as well as molar volume of liquid In-Zn alloys showed almost identical behaviour like the ideal solutions. The observed little deviations were contained within assessed experimental errors.

  16. 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.

  17. Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

    Science.gov (United States)

    Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

    2015-01-01

    The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents.

  18. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

    Directory of Open Access Journals (Sweden)

    S. C. Nagaraju

    2014-01-01

    Full Text Available Polyaniline- (PANI praseodymium Oxide (Pr2O3 composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

  19. 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.

  20. 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...... impacts their adsorption- and tribological properties in comparison to either no purification or mildly purifying dialysis treatment. We show that the properties of the mucins are influenced by the presence of other biomolecules. Bovine serum albumin was determined to be the main protein contaminant...

  1. Structural properties of LPV to LFR transformation: minimality, input-output behavior and identifiability

    OpenAIRE

    Alkhoury, Ziad; Petreczky, Mihály; Mercère, Guillaume

    2016-01-01

    In this paper, we introduce and study important properties of the transformation of Affine Linear Parameter-Varying (ALPV) state-space representations into Linear Fractional Representations (LFR). More precisely, we show that $(i)$ state minimal ALPV representations yield minimal LFRs, and vice versa, $(ii)$ the input-output behavior of the ALPV represention determines uniquely the input-output behavior of the resulting LFR, $(iii)$ structurally identifiable ALPVs yield structurally identifia...

  2. Magellan: electrical and physical properties of venus' surface.

    Science.gov (United States)

    Tyler, G L; Ford, P G; Campbell, D B; Elachi, C; Pettengill, G H; Simpson, R A

    1991-04-12

    Magellan probes Venus' surface by 12.6-cm-wavelength vertical and oblique radar scattering and measures microwave thermal emission. Emissivity and root-meansquare slope maps between 330 degrees and 30 degrees E and 90 degrees N and 80 degrees S are dissimilar, although some local features are exceptions. Inferred surface emissivities typically are approximately 0.85, but vary from approximately 0.35 at Maxwell to approximately 0.95 northeast of Gula Mons and other locations. Lowest emissivities appear in topographically high areas; this relation suggests that a phase change or differences in chemical weathering occur at about 6055-kilometer radius. Initial results indicate that there are significant variations in the surface scattering function.

  3. Magellan - Electrical and physical properties of Venus' surface

    Science.gov (United States)

    Tyler, G. L.; Ford, P. G.; Campbell, D. B.; Elachi, C.; Pettengill, G. H.; Simpson, R. A.

    1991-04-01

    Magellan probes Venus'surface by 12.6-cm-wavelength vertical and oblique radar scattering and measures microwave thermal emission. Emissivity and root-mean-square slope maps between 330 deg and 30 deg E and 90 deg N and 80 deg S are dissimilar, although some local features are exceptions. Inferred surface emissivities typically are 0.85, but vary from 0.35 at Maxwell to 0.95 northeast of Gula Mons and other locations. Lowest emissivities appear in topographically high areas; this relation suggests that a phase change or differences in chemical weathering occur at about 6055-kilometer radius. Initial results indicate that there are significant variations in the surface scattering function.

  4. 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.

  5. Plasmonic properties of metal nanoislands: surface integral equations approach

    Science.gov (United States)

    Scherbak, S. A.; Lipovskii, A. A.

    2016-08-01

    The surface integral equations method is used to analyse the surface plasmon resonance position in a metal island film formed by non-interacting axisymmetrical prolate/oblate hemispheroids placed on a dielectric substrate. The approach is verified via the comparison of results obtained for a hemisphere on a substrate with the ones obtained using the multipole expansion method. The preference of the integral equations method is in obtaining a simple final analytical expression for a particle polarizability in which any dielectric function of a metal can be substituted. Such simple formulae for the hemispherical particle on the substrate and calculated dependences of the hemispheroid resonant wavelength on its aspect ratio are presented.

  6. 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.

  7. Study on the Surface Property of Surfactant Ionic Liquids Solutions

    Institute of Scientific and Technical Information of China (English)

    Yan An GAO; Zhong Ni WANG; Jin ZHANG; Wan Guo HOU; Gan Zuo LI; Bu Xing HAN; Feng Feng Lü; Gao Yong ZHANG

    2005-01-01

    The surfactant TX-100 can be dissolved in ionic liquid bmimPF6 and decrease the surface tension of 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) solutions. Here,we confirmed that in this new system, the pure solvents need rearrangement at the air-water interface at the initial stage. The dynamic surface tension (DST) study shows that at the initial adsorption stage, the adsorption model of surfactant accords with the diffusion-controlled adsorption mechanism, and the dilute ionic liquids solutions is further close to the diffusion-controlled adsorption.

  8. 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.

  9. Effect of surface treatment on mechanical properties of glass fiber/stainless steel wire mesh reinforced epoxy hybrid composites

    Energy Technology Data Exchange (ETDEWEB)

    N, Karunagaran [S.K.P Engineering College, Tiruvannamalai (India); A, Rajadurai [Anna University, Chennai (India)

    2016-06-15

    This paper investigates the effect of surface treatment for glass fiber, stainless steel wire mesh on tensile, flexural, inter-laminar shear and impact properties of glass fiber/stainless steel wire mesh reinforced epoxy hybrid composites. The glass fiber fabric is surface treated either by 1 N solution of sulfuric acid or 1 N solution of sodium hydroxide. The stainless steel wire mesh is also surface treated by either electro dissolution or sand blasting. The hybrid composites are fabricated using epoxy resin reinforced with glass fiber and fine stainless steel wire mesh by hand lay-up technique at room temperature. The hybrid composite consisting of acid treated glass fiber and sand blasted stainless steel wire mesh exhibits a good combination of tensile, flexural, inter-laminar shear and impact behavior in comparison with the composites made without any surface treatment. The fine morphological modifications made on the surface of the glass fiber and stainless steel wire mesh enhances the bonding between the resin and reinforcement which inturn improved the tensile, flexural, inter-laminar shear and impact properties.

  10. 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.

  11. 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.

  12. Bulk and surface properties of demixing liquid Al-Sn and Sn-Tl alloys

    Science.gov (United States)

    Odusote, Y. A.; Popoola, A. I.; Oluyamo, S. S.

    2016-02-01

    The energetics of mixing in Al-Sn and Sn-Tl-segregating binary alloys has been explained through the study of surface properties (surface concentrations and surface tension) and various concentration-dependent thermodynamic (free energy of mixing, entropy of mixing and enthalpy of mixing) and transport (chemical diffusion) properties as well as the microscopic functions (concentration fluctuations in the long-wavelength limits and chemical short-range order parameter) using a statistical mechanical theory in conjunction with the self-association model (SAM). The theoretical property values obtained by the SAM were compared to the corresponding experimental values available in literature.

  13. 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.

  14. Tuning Acoustic Wave Properties by Mechanical Resonators on a Surface

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    Vibrations generated by high aspects ratio electrodes are studied by the finite element method. It is found that the modes are combined of a surface wave and vibration in the electrodes. For increasing aspect ratio most of the mechanical energy is confined to the electrodes which act as mechanical...

  15. Hydrophobic and Electrostatic Cell Surface Properties of Thermophilic Dairy Streptococci

    NARCIS (Netherlands)

    Van der Mei, HC; de Vries, Jacob; Busscher, HJ

    1993-01-01

    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 adde

  16. Tyre - Road Noise, Surface Characteristics and Material Properties

    NARCIS (Netherlands)

    Li, M.

    2013-01-01

    Noise levels due to road traffic have reached intolerable high levels in and around many urban areas all around the world. Because of health reasons and reasons of well- being these noise levels have to be reduced. The noise produced from the interaction between the rolling tyre and road surface is

  17. Surface Engineered Polymeric Biomaterials with Improved Biocontact Properties

    Directory of Open Access Journals (Sweden)

    Todorka G. Vladkova

    2010-01-01

    Full Text Available We present many examples of surface engineered polymeric biomaterials with nanosize modified layers, controlled protein adsorption, and cellular interactions potentially applicable for tissue and/or blood contacting devices, scaffolds for cell culture and tissue engineering, biosensors, biological microchips as well as approaches to their preparation.

  18. Surface-bound microgels - From physicochemical properties to biomedical applications

    DEFF Research Database (Denmark)

    Nyström, Lina; Malmsten, Martin

    2016-01-01

    Microgels offer robust and facile approaches for surface modification, as well as opportunities to introduce biological functionality by loading such structures with bioactive agents, e.g., in the context of drug delivery, functional biomaterials, and biosensors. As such, they provide a versatile...

  19. The surface layer of austempered ductile iron investment castings properties

    OpenAIRE

    D. Myszka; M. Kłębczyk; Zych, A.; L. Kwiatkowski

    2009-01-01

    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.

  20. 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.

  1. Scaling behavior of the surface roughness of platinum films grown by oblique angle deposition

    Science.gov (United States)

    Dolatshahi-Pirouz, A.; Hovgaard, M. B.; Rechendorff, K.; Chevallier, J.; Foss, M.; Besenbacher, F.

    2008-03-01

    Thin platinum films with well-controlled rough surface morphologies are grown by e-gun evaporation at an oblique angle of incidence between the deposition flux and the substrate normal. Atomic force microscopy is used to determine the root-mean-square value w of the surface roughness on the respective surfaces. From the scaling behavior of w , we find that while the roughness exponent α remains nearly unchanged at about 0.90, the growth exponent β changes from 0.49±0.04 to 0.26±0.01 as the deposition angle approaches grazing incidence. The values of the growth exponent β indicate that the film growth is influenced by both surface diffusion and shadowing effects, while the observed change from 0.49 to 0.26 can be attributed to differences in the relative importance of diffusion and shadowing with the deposition angle.

  2. 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.

  3. Ni-Zr alloys: relationship between surface characteristics and electrocatalytic behavior

    Science.gov (United States)

    Angelini; Antonione; Baricco; Daolio; Fabrizio; Rosalbino

    2000-01-01

    A relationship between electrocatalytic activity for the hydrogen evolution reaction and the surface composition of the electrode was established for Ni-Zr crystalline and amorphous alloys by means of secondary ion mass spectrometry (SIMS). Electrocatalytic activity was tested by means of cathodic polarization in 1 M KOH at 25 degrees C and the resulting exchange current density has been taken as a measure of catalytic efficiency. Surface activation treatment involved chemical etching in HF solutions; the consequent morphological and compositional surface changes were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical behavior of the pure elements (Ni and Zr) was also considered for comparison. All samples submitted to chemical etching in HF solutions showed an increase in electrocatalytic activity, particularly the alloy with the highest Ni content. The beneficial effect of chemical etching is due to dissolution of the zirconium oxide layer and to the formation of nanocrystalline Ni on the surfaces.

  4. Study for Reduction of Outgassing Property of Adsorbed Water Gas for Improved Surface Finished Titanium Material

    Science.gov (United States)

    Takeda, Masatoshi; Kurisu, Hiroki; Uchida, Takashi; Yamamoto, Setsuo; Ishizawa, Katsunobu; Nomura, Takeru; Eda, Takahiro; Murashige, Nobuyuki

    This paper addresses the development of the surface finishing for a titanium material and the study for the reduction of outgassing property of adsorbed water (H2O) molecules. Developed surface finishing is composed of the buffing for the reduction of the surface roughness and improved chemical polishing for the thick surface oxide layer compared with the chemical polishing so far. The surface roughness of the surface finished titanium material is reduced 35% and the thickness of the surface oxide layer increases by 30%. The total amount of thermal desorbed H2O gas for the new surface finished titanium is reduced 30%. It is considered that the origin for the decrease of the amount of desorption H2O gas is the reduction of the adsorption sites due to the decrease of the surface roughness and the reduction of adsorption energy of H2O gas due to the strong surface oxidation for a titanium material.

  5. How does γ-irradiation affect the properties of a microfiltration membrane constituted of two polymers with different radiolytic behavior?

    Science.gov (United States)

    Fortin, Nicolas; Albela, Belén; Bonneviot, Laurent; Rouif, Sophie; Sanchez, Jean-Yves; Portinha, Daniel; Fleury, Etienne

    2012-03-01

    The objective of this work is to present the behavior of a fluorinated microporous membrane composed of poly(vinylidene fluoride) (PVDF) mechanically reinforced by a polyamide-66 (PA-66) fabric under γ-irradiation with dose ranging between 0 and 100 kGy, in inert atmosphere and at room temperature. Particular attention was paid to the evolution of mechanical properties, the surface morphology and pores size distribution of this membrane, in order to study the filtration capacity and selectivity with increasing radiation dose. Moreover, the repartition of the generated radicals onto the two components of the membrane was achieved by electron spin resonance (ESR) spectroscopy. Two different regimes are observed depending on the dose range, and a correlation between the mechanical behavior of the membrane and the evolution of the concentration of the radicals in the PA fabric is observed. Globally, the porosity of the surface membrane does not vary whatever the dose may be, but the mechanical properties of the membrane as well as the permeability are strongly affected, even for low radiation dose such as 10 kGy. These results are related to chain scissions on the PA fabric, which occurred preferentially, compared to cross-linking, in the investigated dose range.

  6. 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.

  7. 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.

  8. Influence of surface roughness on nonlinear flow behaviors in 3D self-affine rough fractures: Lattice Boltzmann simulations

    Science.gov (United States)

    Wang, Min; Chen, Yi-Feng; Ma, Guo-Wei; Zhou, Jia-Qing; Zhou, Chuang-Bing

    2016-10-01

    This study investigates the impacts of surface roughness on the nonlinear fluid flow through three-dimensional (3D) self-affine rock fractures, whose original surface roughness is decomposed into primary roughness (i.e. the large-scale waviness of the fracture morphology) and secondary roughness (i.e. the small-scale unevenness) with a wavelet analysis technique. A 3D Lattice Boltzmann method (LBM) is adopted to predict the flow physics in rock fractures numerically created with and without consideration of the secondary roughness, respectively. The simulation results show that the primary roughness mostly controls the pressure distribution and fracture flow paths at a large scale, whereas the secondary roughness determines the nonlinear properties of the fluid flow at a local scale. As the pressure gradient increases, the secondary roughness enhances the local complexity of velocity distribution by generating and expanding the eddy flow and back flow regions in the vicinity of asperities. It was found that the Forchheimer's law characterizes well the nonlinear flow behavior in fractures of varying roughness. The inertial effects induced by the primary roughness differ only marginally in fractures with the roughness exponent varying from 0.5 to 0.8, and it is the secondary roughness that significantly enhances the nonlinear flow and leads to earlier onset of nonlinearity. Further examined were the effects of surface roughness on the transmissivity, hydraulic aperture and the tortuosity of flow paths, demonstrating again the dominant role of the secondary roughness, especially for the apparent transmissivity and the equivalent hydraulic aperture at high pressure gradient or high Reynolds number. The results may enhance our understanding of the role of surface roughness in the nonlinear flow behaviors in natural rock fractures.

  9. Mixed-Mode Fracture Behavior and Related Surface Topography Feature of a Typical Sandstone

    Science.gov (United States)

    Ren, L.; Xie, L. Z.; Xie, H. P.; Ai, T.; He, B.

    2016-08-01

    The geo-mechanical properties of reservoirs, especially the morphology of the rock surface and the fracture properties of rocks, are of great importance in the modeling and simulation of hydraulic processes. To better understand these fundamental issues, five groups of mixed-mode fracture tests were conducted on sandstone using edge-cracked semi-circular bend specimens. Accordingly, the fracture loads, growth paths and fracture surfaces for different initial mixities of the mixed-mode loadings from pure mode I to pure mode II were then determined. A surface topography measurement for each rough fracture surface was conducted using a laser profilometer, and the fractal properties of these surfaces were then investigated. The fracture path evolution mechanism was also investigated via optical microscopy. Moreover, the mixed-mode fracture strength envelope and the crack propagation trajectories of sandstone were theoretically modeled using three widely accepted fracture criteria (i.e., the MTS, MSED and MERR criterions). The published test results in Hasanpour and Choupani (World Acad Sci Eng Tech 41:764-769, 2008) for limestone were also theoretically investigated to further examine the effectiveness of the above fracture criteria. However, none of these criteria could accurately predict the fracture envelopes of both sandstone and limestone. To better estimate the fracture strength of mixed-mode fractures, an empirical maximum tensile stress (EMTS) criterion was proposed and found to achieve good agreement with the test results. Finally, a uniformly pressurized fracture model was simulated for low pressurization rates using this criterion.

  10. 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.

  11. Microstructural evolution and surface properties of nanostructured Cu-based alloy by ultrasonic nanocrystalline surface modification technique

    Science.gov (United States)

    Amanov, Auezhan; Cho, In-Sik; Pyun, Young-Sik

    2016-12-01

    A nanostructured surface layer with a thickness of about 180 μm was successfully produced in Cu-based alloy using an ultrasonic nanocrystalline surface modification (UNSM) technique. Cu-based alloy was sintered onto low carbon steel using a powder metallurgy (P/M) method. Transmission electron microscope (TEM) characterization revealed that the severe plastic deformation introduced by UNSM technique resulted in nano-sized grains in the topmost surface layer and deformation twins. It was also found by atomic force microscope (AFM) observations that the UNSM technique provides a significant reduction in number of interconnected pores. The effectiveness of nanostructured surface layer on the tribological and micro-scratch properties of Cu-based alloy specimens was investigated using a ball-on-disk tribometer and micro-scratch tester, respectively. Results exhibited that the UNSM-treated specimen led to an improvement in tribological and micro-scratch properties compared to that of the sintered specimen, which may be attributed to the presence of nanostructured surface layer having an increase in surface hardness and reduction in surface roughness. The findings from this study are expected to be implemented to the automotive industry, in particular connected rod bearings and bushings in order to increase the efficiency and performance of internal combustion engines (ICEs).

  12. 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.

  13. 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.

  14. 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.

  15. Asymmetric interference between the perception of shape and the perception of surface properties.

    Science.gov (United States)

    Cant, Jonathan S; Goodale, Melvyn A

    2009-05-14

    We previously showed that the processing of shape and the processing of surface properties linked to material properties engage different regions of the ventral stream (J. S. Cant & M. A. Goodale, 2007). Moreover, we recently used Garner's speeded-classification task to show that varying the surface (material) properties of objects does not interfere with shape judgments and vice versa (J. S. Cant, M. E. Large, L. McCall, & M. A. Goodale, 2008). In the present study, we looked at Garner interference when surface cues contributed to the perception of object shape and hypothesized that this would interfere with judgments about the width and the length of the objects. In contrast, we predicted that varying the width and the length of the objects would not interfere with surface-property judgments. This is precisely what we found. These results suggest that the shape and the surface properties of an object cannot be processed independently when both these sets of cues are linked to the perception of the object's overall shape. These observations, together with our previous findings, suggest that the surface cues that contribute to object shape are processed quite separately from the surface cues that are linked to an object's material properties.

  16. Surface analysis and biocorrosion properties of nanostructured surface sol-gel coatings on Ti6Al4V titanium alloy implants.

    Science.gov (United States)

    Advincula, Maria C; Petersen, Don; Rahemtulla, Firoz; Advincula, Rigoberto; Lemons, Jack E

    2007-01-01

    Surfaces of biocompatible alloys used as implants play a significant role in their osseointegration. Surface sol-gel processing (SSP), a variant of the bulk sol-gel technique, is a relatively new process to prepare bioreactive nanostructured titanium oxide for thin film coatings. The surface topography, roughness, and composition of sol-gel processed Ti6Al4V titanium alloy coatings was investigated by atomic force microscopy (AFM) and X-ray electron spectroscopy (XPS). This was correlated with corrosion properties, adhesive strength, and bioreactivity in simulated body fluids (SBF). Electroimpedance spectroscopy (EIS) and polarization studies indicated similar advantageous corrosion properties between sol-gel coated and uncoated Ti6Al4V, which was attributed to the stable TiO2 composition, topography, and adhesive strength of the sol-gel coating. In addition, inductive coupled plasma (ICP) and scanning electron microscopy with energy dispersive spectrometry (SEM-EDS) analysis of substrates immersed in SBF revealed higher deposition of calcium and phosphate and low release rates of alloying elements from the sol-gel modified alloys. The equivalent corrosion behavior and the definite increase in nucleation of calcium apatite indicate the potential of the sol-gel coating for enhanced bioimplant applications.

  17. 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.

  18. 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...

  19. Surface relaxations as a tool to distinguish the dynamic interfacial properties of films formed by normal and diseased meibomian lipids.

    Science.gov (United States)

    Georgiev, Georgi As; Yokoi, Norihiko; Ivanova, Slavyana; Tonchev, Vesselin; Nencheva, Yana; Krastev, Rumen

    2014-08-14

    The surface properties of human meibomian lipids (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The dynamic interfacial properties of films by MGS from normal eyes (nMGS) and eyes with meibomian gland dysfunction (dMGS) were studied using a Langmuir surface balance. The behavior of the samples during dynamic area changes was evaluated by surface pressure-area isotherms and isocycles. The surface dilatational rheology of the films was examined in the frequency range 10(-5) to 1 Hz by the stress-relaxation method. A significant difference was found, with dMGS showing slow viscosity-dominated relaxation at 10(-4) to 10(-3) Hz, whereas nMGS remained predominantly elastic over the whole range. A Cole-Cole plot revealed two characteristic processes contributing to the relaxation, fast (on the scale of characteristic time τ 100 s), the latter prevailing in dMGS films. Brewster angle microscopy revealed better spreading of nMGS at the air-water interface, whereas dMGS layers were non-uniform and patchy. The distinctions in the interfacial properties of the films in vitro correlated with the accelerated degradation of meibum layer pattern at the air-tear interface and with the decreased stability of TF in vivo. These results, and also recent findings on the modest capability of meibum to suppress the evaporation of the aqueous subphase, suggest the need for a re-evaluation of the role of MGS. The probable key function of meibomian lipids might be to form viscoelastic films capable of opposing dilation of the air-tear interface. The impact of temperature on the meibum surface properties is discussed in terms of its possible effect on the normal structure of the film.

  20. 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.

  1. Sterilisation properties of the Mars surface and atmospheric environment.

    Science.gov (United States)

    Moreau, D; Muller, C

    2003-01-01

    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.

  2. Application of Anodization Process for Cast Aluminium Surface Properties Enhancement

    Directory of Open Access Journals (Sweden)

    Włodarczyk-Fligier A.

    2016-09-01

    Full Text Available An huge interest is observed in last years in metal matrix composite, mostly light metal based, which have found their applications in many industry branches, among others in the aircraft industry, automotive-, and armaments ones, as well as in electrical engineering and electronics, where one of the most important issue is related to the corrosion resistance, especially on the surface layer of the used aluminium alloys. This elaboration presents the influence of ceramic phase on the corrosion resistance, quality of the surface layer its thickness and structure of an anodic layer formed on aluminium alloys. As test materials it was applied the aluminium alloys Al-Si-Cu and Al-Cu-Mg, for which heat treatment processes and corrosion tests were carried out. It was presented herein grindability test results and metallographic examination, as well. Hardness of the treated alloys with those ones subjected to corrosion process were compared.

  3. Tethered polymer chains : surface chemistry and their impact on colloidal and surface properties

    NARCIS (Netherlands)

    Currie, EPK; Norde, W; Stuart, Martien A. Cohen

    2003-01-01

    In this review the grafting of polymer chains to solid supports or interfaces and the subsequent impact on colloidal properties is examined. We start by examining theoretical models for densely grafted polymers (brushes), experimental techniques for their preparation and the properties of the ensuin

  4. Tethered polymer chains: surface chemistry and their impact on colloidal and surface properties

    NARCIS (Netherlands)

    Currie, E.P.K.; Norde, W.; Cohen Stuart, M.A.

    2003-01-01

    In this review the grafting of polymer chains to solid supports or interfaces and the subsequent impact on colloidal properties is examined. We start by examining theoretical models for densely grafted polymers (brushes), experimental techniques for their preparation and the properties of the ensuin

  5. Optical properties of surface plasmon resonances of coupled metallic nanorods.

    Science.gov (United States)

    Smythe, Elizabeth J; Cubukcu, Ertugrul; Capasso, Federico

    2007-06-11

    We present a systematic study of optical antenna arrays, in which the effects of coupling between the antennas, as well as of the antenna length, on the reflection spectra are investigated and compared. Such arrays can be fabricated on the facet of a fiber, and we propose a photonic device, a plasmonic optical antenna fiber probe, that can potentially be used for in-situ chemical and biological detection and surface-enhanced Raman scattering.

  6. Hall-effect Thruster Channel Surface Properties Investigation (PREPRINT)

    Science.gov (United States)

    2011-03-03

    beryllium window separating the specimen vacuum chamber and the Lithium- drifted Silicon detector. Within the detector, the photons pass into a cooled...palladium alloy is applied to the samples. The samples are placed into a vacuum chamber where the gold-palladium is sputtered onto the sample surface in...graphite beam dump used during vacuum chamber testing; this carbon deposition initially has a fairly uniform concentration. The non-uniformity of carbon

  7. 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.

  8. 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.

  9. Investigating Surface Effects on Thermomechanical Behavior of Embedded Circular Curved Nanosize Beams

    Directory of Open Access Journals (Sweden)

    Farzad Ebrahimi

    2016-01-01

    Full Text Available To investigate the surface effects on thermomechanical vibration and buckling of embedded circular curved nanosize beams, nonlocal elasticity model is used in combination with surface properties including surface elasticity, surface tension, and surface density for modeling the nanoscale effect. The governing equations are determined via the energy method. Analytically Navier method is utilized to solve the governing equations for simply supported nanobeam at both ends. Solving these equations enables us to estimate the natural frequency and critical buckling load for circular curved nanobeam including Winkler and Pasternak elastic foundations and under the effect of a uniform temperature change. The results determined are verified by comparing the results with available ones in literature. The effects of various parameters such as nonlocal parameter, surface properties, Winkler and Pasternak elastic foundations, temperature, and opening angle of circular curved nanobeam on the natural frequency and critical buckling load are successfully studied. The results reveal that the natural frequency and critical buckling load of circular curved nanobeam are significantly influenced by these effects.

  10. 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.

  11. Probing the surface profile and friction behavior of heterogeneous polymers: a molecular dynamics study

    Science.gov (United States)

    Dai, L.; Sorkin, V.; Zhang, Y. W.

    2017-04-01

    We perform molecular dynamics simulations to investigate molecular structure alternation and friction behavior of heterogeneous polymer (perfluoropolyether) surfaces using a nanoscale probing tip (tetrahedral amorphous carbon). It is found that depending on the magnitude of the applied normal force, three regimes exist: the shallow depth-sensing (SDS), deep depth-sensing (DDS), and transitional depth-sensing (TDS) regimes; TDS is between SDS and DDS. In SDS, the tip is floating on the polymer surface and there is insignificant permanent alternation in the polymer structure due to largely recoverable atomic deformations, and the surface roughness profile can be accurately measured. In DDS, the tip is plowing through the polymer surface and there is significant permanent alternation in the molecular structure. In this regime, the lateral friction force rises sharply and fluctuates violently when overcoming surface pile-ups. In SDS, the friction can be described by a modified Amonton’s law including the adhesion effect; meanwhile, in DDS, the adhesion effect is negligible but the friction coefficient is significantly higher. The underlying reason for the difference in these regimes rests upon different contributions by the repulsion and attraction forces between the tip and polymer surfaces to the friction force. Our findings here reveal important insights into lateral depth-sensing on heterogeneous polymer surfaces and may help improve the precision of depth-sensing devices.

  12. STRUCTURAL AND PHYSICOCHEMICAL SURFACE-PROPERTIES OF SERRATIA-MARCESCENS STRAINS

    NARCIS (Netherlands)

    VANDERMEI, HC; COWAN, MM; GENET, MJ; ROUXHET, PG; BUSSCHER, HJ

    1992-01-01

    Serratia marcescens is an important pathogen with noteworthy hydrophobicity characteristics as assessed by microbial adhesion to hydrocarbons. However, the present knowledge on the surface characteristics of S. marcescens strains does not include physicochemical properties relevant for adhesion such

  13. Surface electronic and structural properties of nanostructured titanium oxide grown by pulsed laser deposition

    NARCIS (Netherlands)

    Fusi, M.; Maccallini, E.; Caruso, T.; Casari, C. S.; Bassi, A. Li; Bottani, C. E.; Rudolf, P.; Prince, K. C.; Agostino, R. G.

    2011-01-01

    Titanium oxide nanostructured thin films synthesized by pulsed laser deposition (PLD) were here characterized with a multi-technique approach to investigate the relation between surface electronic, structural and morphological properties. Depending on the growth parameters, these films present chara

  14. Dynamic Viscoelasticity and Surface Properties of Porcine Left Anterior Descending Coronary Arteries.

    Science.gov (United States)

    Burton, Hanna E; Freij, Jenny M; Espino, Daniel M

    2017-03-01

    The aim of this study was, for the first time, to measure and compare quantitatively the viscoelastic properties and surface roughness of coronary arteries. Porcine left anterior descending coronary arteries were dissected ex vivo. Viscoelastic properties were measured longitudinally using dynamic mechanical analysis, for a range of frequencies from 0.5 to 10 Hz. Surface roughness was calculated following three-dimensional reconstructed of surface images obtained using an optical microscope. Storage modulus ranged from 14.47 to 25.82 MPa, and was found to be frequency-dependent, decreasing as the frequency increased. Storage was greater than the loss modulus, with the latter found to be frequency-independent with a mean value of 2.10 ± 0.33 MPa. The circumferential surface roughness was significantly greater (p surface roughness, ranging from 0.73 to 2.83 and 0.35 to 0.92 µm, respectively. However, if surface roughness values were corrected for shrinkage during processing, circumferential and longitudinal surface roughness were not significantly different (1.04 ± 0.47, 0.89 ± 0.27 µm, respectively; p > 0.05). No correlation was found between the viscoelastic properties and surface roughness. It is feasible to quantitatively measure the viscoelastic properties of coronary arteries and the roughness of their endothelial surface.

  15. 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)

  16. Surface behavior of amphiphiles in aqueous solution: a comparison between different pentanol isomers.

    Science.gov (United States)

    Walz, M-M; Caleman, C; Werner, J; Ekholm, V; Lundberg, D; Prisle, N L; Öhrwall, G; Björneholm, O

    2015-06-07

    Position isomerism is ubiquitous in atmospheric oxidation reactions. Therefore, we have compared surface-active oxygenated amphiphilic isomers (1- and 3-pentanol) at the aqueous surface with surface- and chemically sensitive X-ray photoelectron spectroscopy (XPS), which reveals information about the surface structure on a molecular level. The experimental data are complemented with molecular dynamics (MD) simulations. A concentration-dependent orientation and solvation of the amphiphiles at the aqueous surface is observed. At bulk concentrations as low as around 100 mM, a monolayer starts to form for both isomers, with the hydroxyl groups pointing towards the bulk water and the alkyl chains pointing towards the vacuum. The monolayer (ML) packing density of 3-pentanol is approx. 70% of the one observed for 1-pentanol, with a molar surface concentration that is approx. 90 times higher than the bulk concentration for both molecules. The molecular area at ML coverage (≈100 mM) was calculated to be around 32 ± 2 Å(2) per molecule for 1-pentanol and around 46 ± 2 Å(2) per molecule for 3-pentanol, which results in a higher surface concentration (molecules per cm(2)) for the linear isomer. In general we conclude therefore that isomers - with comparable surface activities - that have smaller molecular areas will be more abundant at the interface in comparison to isomers with larger molecular areas, which might be of crucial importance for the understanding of key properties of aerosols, such as evaporation and uptake capabilities as well as their reactivity.

  17. Fluorine gas treatment improves surface degradation inhibiting property of alumina-filled epoxy composite

    Directory of Open Access Journals (Sweden)

    Chuanyang Li

    2016-02-01

    Full Text Available Epoxy resins blended with micro-sized alumina show more compact surface condition and exhibit lower light emission after modified in fluorinated atmosphere. Surface morphology reflected by atomic force microscope shows that the fluorinated surface layer can overlap alumina particles inlayed in the original surface and a smoother and more compact surface condition is generated. Thermally stimulated current test exhibits that surface fluorination is able to bring more shallow traps to surface states, and the trap amount increases with the extension of fluorinating time. The photon counting technique illustrates that the fluorinated surface has lower light emission which indicates better aging inhibition properties. Therefore, we believe that the surface fluorination technique may have potential significance in modifying epoxy based insulators used in high voltage applications.

  18. Relation between surface properties of thin composite films and osteoblast behaviour in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Polak, B [Department of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00 664, Warsaw (Poland); Olkowski, R [Department of Biophysics and Human Physiology, Medical University of Warsaw, Chalubinskiego 5, 02 004 Warsaw (Poland); Kobiela, T [Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, 02-668 Warsaw (Poland); Lewandowska-Szumiel, M [Department of Biophysics and Human Physiology, Medical University of Warsaw, Chalubinskiego 5, 02 004 Warsaw (Poland); Fabianowski, W [Department of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00 664, Warsaw (Poland)

    2007-07-18

    Si supports for cell culture were modified using poly(acrylic acid) (PAA) and bentonite in order to obtain 'sandwich'-like structures. A layer of PAA cast from water solution was followed with a bentonite layer also cast from water dispersion, then another PAA layer and so on up to six layers. The prepared surfaces had different physical and chemical properties like thickness, topography and elasticity. Chemical composition was characterized by Raman spectroscopy. The elastic properties and topography of modified sandwich-like surfaces were evaluated using nanoindentation and atomic force microscopy measurements. In the next step bone cells were cultured on such modified surfaces composed of one to six layers. The influence of the substrate surface properties on the growth and behaviour of human bone derived cells (HBDC) was studied. The influence of surface topography, elasticity and chemical composition on cells is discussed.

  19. Experimental studies on the surface and interfacial properties of polysiloxanes and their interaction with blood proteins

    Science.gov (United States)

    Stuart, James Oliver

    1998-12-01

    The research in this thesis is concerned with the surface and interfacial properties of polysiloxanes and their interaction with blood proteins, particularly fibrinogen. Polysiloxane properties at the polymer/air interface were investigated using secondary ion mass spectrometry (SIMS) and contact angle measurements. Polysiloxane properties at the polymer/water interface were studied using a Langmuir film balance. Interaction with blood proteins was investigated by SIMS and by aggregation studies of polysiloxanes emulsified in the presence of various blood components, namely serum, plasma, and fibrinogen solution upon exposure to the enzyme thrombin. Poly(dimethylsiloxane) (PDMS), poly(phenylmethylsiloxane) (PPMS), and poly(trifluoropropylmethylsiloxane) (PTFPMS) homopolymers and diblock copolymers thereof were studied using SIMS and contact angle measurements. Also studied were a newly synthesized series of random copolymers of poly(methyl(methyl undecanoate)siloxane)-co-poly(dimethylsiloxane) (PMMUS). Key findings include the resolution of discrepancies in SIMS mass fragment assignments in PDMS and establishment of mass peak assignments for PPMS, PTFPMS, and PMMUS. Also, it was shown by SIMS that complete surface saturation of the siloxane components of solution casts films of PDMS/PS and PTFPMS/PS diblock copolymers and blends with PS was achieved at siloxane concentrations as low as 2.0 percent by weight. On the other hand, PPMS/PS diblock copolymers show signature peaks of both polymers at siloxane concentrations as high as 51 percent by weight. All results correspond well with contact angle measurements on the same systems. Finally, the detection of trimethylsilyl end-groups was determined through systemic variation of chain termini and polymer molecular weight. The monolayer behavior of the PMMUS copolymer series of the siloxanes containing cholesteryl ester side-groups was examined using a langmuir film balance. The isotherms of the PMMUS polymers showed

  20. 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.

  1. 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.

  2. 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.

  3. Properties and significance of the surface dipole mode

    CERN Document Server

    Papakonstantinou, P

    2014-01-01

    A strong isoscalar dipole resonance is known to be excited in a variety of nuclei, including isospin symmetric ones, at approximately 6-7 MeV. A series of theoretical studies and accumulating experimental evidence support an interpretation of the above dipole resonance as an elementary surface vibration. Obviously, such a mode is potentially as interesting as any collective excitation for a variety of reasons. In addition, though, it is found to account for the observed isoscalar segment of pygmy dipole strength. As discussed here, this has important implications for pygmy-strength interpretations and searches for genuine neutron-skin oscillations.

  4. Mechanical Properties of Glass Surfaces Coated with Tin Oxide

    DEFF Research Database (Denmark)

    Swindlehurst, W. E.; Cantor, B.

    1978-01-01

    of tin tetrachloride on industrial soda glass at ~800K to thicknesses of ~3×10-8 and 3×10 -7 m, commercially by the `titanising' process on industrial soda glass at ~800K to a thickness of ~3.10-9 m, and in the laboratory by radio frequency sputtering from tin oxide powder over a range of glass......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. Psychometric Properties of the Polish Adaptation of the Infant Behavior Questionnaire-Revised (IBQ-R)

    Science.gov (United States)

    Dragan, Wojciech L.; Kmita, Grazyna; Fronczyk, Krzysztof

    2011-01-01

    This paper presents the psychometric properties of the Polish version of the Infant Behavior Questionnaire&-Revised (IBQ-R). A group of 396 pairs of parents was studied, and a 3-factor structure of IBQ-R emerged with differences comparing to the original U.S. sample and a prior replication Russian sample. Analyses demonstrated satisfactory…

  6. Contrasting Roles of Dopamine and Noradrenaline in the Motivational Properties of Social Play Behavior in Rats

    NARCIS (Netherlands)

    Achterberg, E.J.M.; van Kerkhof, L.W.M.; Servadio, Michela; van Swieten, Maaike; Houwing, Danielle J; Aalderink, Mandy; Driel, Nina V; Trezza, Viviana; Vanderschuren, L.J.M.J.

    2016-01-01

    Social play behavior, abundant in the young of many mammalian species, is generally assumed to be important for social and cognitive development. Social play is highly rewarding, and as such, the expression of social play depends on its pleasurable and motivational properties. Since the motivational

  7. 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.

  8. Cell behavior on gallium nitride surfaces: peptide affinity attachment versus covalent functionalization.

    Science.gov (United States)

    Foster, Corey M; Collazo, Ramon; Sitar, Zlatko; Ivanisevic, Albena

    2013-07-02

    Gallium nitride is a wide band gap semiconductor that demonstrates a unique set of optical and electrical properties as well as aqueous stability and biocompatibility. This combination of properties makes gallium nitride a strong candidate for use in chemical and biological applications such as sensors and neural interfaces. Molecular modification can be used to enhance the functionality and properties of the gallium nitride surface. Here, gallium nitride surfaces were functionalized with a PC12 cell adhesion promoting peptide using covalent and affinity driven attachment methods. The covalent scheme proceeded by Grignard reaction and olefin metathesis while the affinity driven scheme utilized the recognition peptide isolated through phage display. This study shows that the method of attaching the adhesion peptide influences PC12 cell adhesion and differentiation as measured by cell density and morphological analysis. Covalent attachment promoted monolayer and dispersed cell adhesion while affinity driven attachment promoted multilayer cell agglomeration. Higher cell density was observed on surfaces modified using the recognition peptide. The results suggest that the covalent and affinity driven attachment methods are both suitable for promoting PC12 cell adhesion to the gallium nitride surface, though each method may be preferentially suited for distinct applications.

  9. Biological properties of Lactobacillus surface proteins 

    Directory of Open Access Journals (Sweden)

    Barbara Buda

    2013-04-01

    Full Text Available Lactobacillus, a genus of Gram-positive bacteria, includes many strains of probiotic microflora. Probiotics, by definition, are living microorganisms that exert beneficial effects on the host organism. The morphology and physiology of the Lactobacillus bacterial genus are described. The structure of the cell wall of Gram-positive bacteria is discussed. The surface S-layer of Lactobacillus composed of proteins (SLP with low molecular mass is presented. Cell surface proteins participating in the regulation of growth and survival of the intestinal epithelium cells are characterized. The influence of stress factors such as increased temperature, pH, and enzymes of gastric and pancreatic juice on SLP expression is described. The ability of binding of heavy metal ions by S-layer proteins is discussed. The characteristics of these structures, including the ability to adhere to epithelial cells, and the inhibition of invasion of pathogenic microflora of type Shigella, Salmonella, Escherichia coli and Clostridium and their toxins, are presented. 

  10. Properties of Galaxies in the Disc Central Surface Brightness Gap

    CERN Document Server

    Sorce, Jenny G; Libeskind, Noam I

    2015-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the S4G survey, complete down to M_B=-16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10% probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbors), the mass and mu_0 are correlated at 2.5 (2) sigma more than for those in sheets. ISBs live in regions where the divergence of the velocity field is sma...

  11. Properties of galaxies in the disc central surface brightness gap

    Science.gov (United States)

    Sorce, Jenny G.; Creasey, Peter; Libeskind, Noam I.

    2016-01-01

    Intermediate surface brightness (ISB) galaxies are less numerous than their counterparts at high and low surface brightness (HSB and LSB). Investigating ISB characteristics from a sample from the Spitzer Survey of Stellar Structure in Galaxies survey, complete down to MB = -16, we find that they have intermediate stellar, gas and baryonic masses and on average as much gas as stars. They lie on the (baryonic) Tully-Fisher relation between HSBs and LSBs, although they present a higher scatter than the latter. Their stellar to baryonic mass ratios have intermediate values unlike their condensed baryonic fractions. By comparing their environments, as classified by the eigenvalues of the velocity shear tensor of local constrained simulations, ISBs have a 5-10 per cent probability higher (smaller) to be in sheets (filaments) with respect to HSBs and LSBs. Additionally, for galaxies in filaments (with close neighbours), the mass and μ0 are correlated at 2.5 (2)σ more than for those in sheets. ISBs live in regions where the divergence of the velocity field is smaller than where HSBs and LSBs live, a result at more than 50 per cent significance. ISBs may exist as an unstable transition state between LSBs and HSBs, the low flow activity environment maximally encouraging their formation. Interaction events altering the central baryon fraction could happen at a lower rate in these less dense environment, whilst in the higher density environments the LSBs are primarily satellite galaxies, whose accretion is sufficiently constrained that it fails to promote them to HSBs.

  12. The impact of surface properties on particle-interface interactions

    Science.gov (United States)

    Wang, Anna; Kaz, David; McGorty, Ryan; Manoharan, Vinothan N.

    2013-03-01

    The propensity for particles to bind to oil-water interfaces was first noted by Ramsden and Pickering over a century ago, and has been attributed to the huge reduction in surface energy when a particle breaches an oil-water interface and straddles it at its equilibrium height. Since then materials on a variety of length scales have been fabricated using particles at interfaces, from Pickering emulsions to Janus particles. In these applications, it is simply assumed that the particle sits at its hugely energetically favourable equilibrium position. However, it was recently shown that the relaxation of particles towards their equilibrium position is logarithmic in time and could take months, much longer than typical experiments. Here we investigate how surface charge and particle 'hairiness' impact the interaction between micron-sized particles and oil-water interfaces, and explore a molecular kinetic theory model to help understand these results. We use digital holographic microscopy to track micron-sized particles as they approach an oil-water interface with a resolution of 2 nm in all three dimensions at up to thousands of frames per second.

  13. Structure and surface properties of praseodymium modified alumina

    Energy Technology Data Exchange (ETDEWEB)

    Tankov, I. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Pawelec, B. [Instituto de Catalisis y Petroleoquimica, CSIC, Cantoblanco, 28049 Madrid (Spain); Arishtirova, K. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Damyanova, S., E-mail: soniad@ic.bas.bg [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2011-10-15

    Mixed PrO{sub 2}-Al{sub 2}O{sub 3} oxides with different PrO{sub 2} content (1-20 wt.%) were prepared by wetness impregnation of {gamma}-alumina with aqueous solution of praseodymium nitrate. The samples were characterized by different techniques, using surface adsorption-desorption of N{sub 2} (S{sub BET}), 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 CO{sub 2} (TPD-CO{sub 2}). 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 Pr{sub 6}O{sub 11}. TPD-CO{sub 2} studies suggested that the deposition of Pr oxide on alumina leaded to increase of the basicity of mixed oxides.

  14. 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.

  15. 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.

  16. Surface properties and phosphate adsorption of binary systems containing goethite and kaolinite

    NARCIS (Netherlands)

    Wei, S.Y.; Tan, W.F.; Liu, F.; Zhao, W.; Weng, L.

    2014-01-01

    In soils goethite and kaolinite are often cemented together as a binary association, which has a significant influence on the physical and chemical properties of soils. In this study, the surface properties and phosphate adsorption of goethite, kaolinite, goethite-kaolinite association (GKA) and goe

  17. AN INFLUENCE OF THE SURFACE ROLLING ON MECHANICAL PROPERTIES OF THE BAND SAW BLADES

    Directory of Open Access Journals (Sweden)

    Daniela Kalincová

    2009-05-01

    Full Text Available The article present the experiment focused on the band saw blade surface mechanical properties analysis after plastic deformation process. The deformation of the band saw blade is caused by rootling in order to increase operating reliability. Mechanical properties were evaluated by hardness measurement and by microstructure analysis.

  18. Evaluating non-stick properties of different surface materials for contact frying

    DEFF Research Database (Denmark)

    Ashokkumar, Saranya; Adler-Nissen, Jens

    2011-01-01

    to evaluate non-stick and cleaning properties of the coatings. In accordance with industry standards pancake was selected as the food model for the non-stick properties. The performance of different frying surfaces (stainless steel, aluminium, PTFE (polytetrafluoroethylene) and three ceramic coatings with two...

  19. Low-temperature oxidizing plasma surface modification and composite polymer thin-film fabrication techniques for tailoring the composition and behavior of polymer surfaces

    Science.gov (United States)

    Tompkins, Brendan D.

    This dissertation examines methods for modifying the composition and behavior of polymer material surfaces. This is accomplished using (1) low-temperature low-density oxidizing plasmas to etch and implant new functionality on polymers, and (2) plasma enhanced chemical vapor deposition (PECVD) techniques to fabricate composite polymer materials. Emphases are placed on the structure of modified polymer surfaces, the evolution of polymer surfaces after treatment, and the species responsible for modifying polymers during plasma processing. H2O vapor plasma modification of high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polycarbonate (PC), and 75A polyurethane (PU) was examined to further our understanding of polymer surface reorganization leading to hydrophobic recovery. Water contact angles (wCA) measurements showed that PP and PS were the most susceptible to hydrophobic recovery, while PC and HDPE were the most stable. X-ray photoelectron spectroscopy (XPS) revealed a significant quantity of polar functional groups on the surface of all treated polymer samples. Shifts in the C1s binding energies (BE) with sample age were measured on PP and PS, revealing that surface reorganization was responsible for hydrophobic recovery on these materials. Differential scanning calorimetry (DSC) was used to rule out the intrinsic thermal properties as the cause of reorganization and hydrophobic recovery on HDPE, LDPE, and PP. The different contributions that polymer cross-linking and chain scission mechanisms make to polymer aging effects are considered. The H2O plasma treatment technique was extended to the modification of 0.2 microm and 3.0 microm track-etched polycarbonate (PC-TE) and track-etched polyethylene terephthalate (PET-TE) membranes with the goal of permanently increasing the hydrophilicity of the membrane surfaces. Contact angle measurements on freshly treated and aged samples confirmed the wettability of the

  20. Surface decomposition and annealing behavior of GaN implanted with Eu

    CERN Document Server

    Liu Hua Ming; Chen Chang Chun; Wang Sen; Zhu De Zhang; Xu Hong Jie

    2002-01-01

    Investigations on surface decomposition of GaN implanted with low energy (80 keV) Eu ion to a low dose (1 x 10 sup 1 sup 4 cm sup - sup 2), and its annealing behavior under high temperature (1050 degree C) in N sub 2 are performed. The as-grown, as-implanted and annealed GaN films are characterized by proton elastic scattering (PES), Rutherford backscattering spectrometry (RBS), photoluminescence (PL) and atomic force microscopy (AFM). The results show that Eu ion implantation induces radiation defects and decomposition of GaN. The GaN surface decomposition is more serious during high temperature annealing. The atomic ratio of N in as-grown, as-implanted and annealed GaN film is 47 at.%, 44 at.% and 40 at.%, respectively. As a result, a rough Ga-rich layer is formed at the surface, though the lattice defects are partly removed after high temperature annealing

  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. 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.

  3. Surface Functionalization of Thin-Film Composite Membranes with Copper Nanoparticles for Antimicrobial Surface Properties

    KAUST Repository

    Ben-Sasson, Moshe

    2014-01-07

    Biofouling is a major operational challenge in reverse osmosis (RO) desalination, motivating a search for improved biofouling control strategies. Copper, long known for its antibacterial activity and relatively low cost, is an attractive potential biocidal agent. In this paper, we present a method for loading copper nanoparticles (Cu-NPs) on the surface of a thin-film composite (TFC) polyamide RO membrane. Cu-NPs were synthesized using polyethyleneimine (PEI) as a capping agent, resulting in particles with an average radius of 34 nm and a copper content between 39 and 49 wt.%. The positive charge of the Cu-NPs imparted by the PEI allowed a simple electrostatic functionalization of the negatively charged RO membrane. We confirmed functionalization and irreversible binding of the Cu-NPs to the membrane surface with SEM and XPS after exposing the membrane to bath sonication. We also demonstrated that Cu-NP functionalization can be repeated after the Cu-NPs dissolve from the membrane surface. The Cu-NP functionalization had minimal impact on the intrinsic membrane transport parameters. Surface hydrophilicity and surface roughness were also maintained, and the membrane surface charge became positive after functionalization. The functionalized membrane exhibited significant antibacterial activity, leading to an 80-95% reduction in the number of attached live bacteria for three different model bacterial strains. Challenges associated with this functionalization method and its implementation in RO desalination are discussed. © 2013 American Chemical Society.

  4. A study of the surface charging properties of a standard strain of Escherichia coli (ATCC 11775) in aqueous solutions.

    Science.gov (United States)

    Li, Xinpeng; Xue, Xinkai; Pashley, Richard M

    2015-11-01

    In this study, the Escherichia coli (E. coli) strain ATCC 11775 was studied to determine its surface charging properties in a range of different aqueous salt solutions, with the aim of evaluating its potential as a monitor organism for water treatment. Zeta potential measurements were carried out in various solutions containing: NaCl, CaCl2, MgSO4, ZnSO4 and C14TAB, at different pH values and concentrations. Interestingly, it was found that the zeta potential of this strain of E. coli remained fairly constant at pH values over about 6, in 1mM NaCl solutions. In order to explain the cell surface charging properties, a simple, mass action surface ionization model was developed. This model indicates that the surface charging of these E. coli cells can be modeled simply using the ionization behavior of the acid groups in the common anionic membrane lipid phosphatidylserine (PS). There appeared to be no specific, strong adsorption of either divalent anions or cations, until high salt concentrations, above about 0.1M. The results suggest that at high concentrations both Ca(2+) and SO4(2-) ions are strongly adsorbed at the cell surface. However reduction of the magnitude of the surface electrostatic potential, due to Ca(2+) ion adsorption, did not appear to cause any cellular binding. In comparison, cationic surfactant was strongly adsorbed by the cell membrane surface, even at concentrations of 0.1mM, and light scattering studies indicated that the adsorption of the surfactant appeared to lyse the cell membrane and release internal cellular materials leading to a significant reduction in cell size.

  5. Surface and bulk dissolution properties, and selectivity of DNA-linked nanoparticle assemblies

    NARCIS (Netherlands)

    Lukatsky, D.B.; Frenkel, D.

    2005-01-01

    Using a simple mean-field model, we analyze the surface and bulk dissolution properties of DNA-linked nanoparticle assemblies. We find that the dissolution temperature and the sharpness of the dissolution profiles increase with the grafting density of the single-stranded DNA "probes" on the surface

  6. 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...

  7. Covalently bound organic monolayers on silicon surfaces : visible light attachment, charaterization, and electrical properties

    NARCIS (Netherlands)

    Smet, de L.C.P.M.

    2006-01-01

    The full control over surface properties is a 'Holy Grail' in material science. A significant step forward in this area includes the modification of silicon surfaces, by the covalent attachment of organic monolayers. In this way receptors than can specifically bind with ions or molecules be attached

  8. 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

    affected the surface properties. All three RG-I induced bone matrix formation and mineralization, which was also supported by the finding that gene expression levels of alkaline phosphatase, osteocalcin, and collagen type-1 were increased in cells cultured on the RG-I coated surface, indicating a more...

  9. Multiple surface properties of worn RGP lenses and adhesion of Pseudomonas aeruginosa

    NARCIS (Netherlands)

    Bruinsma, Gerda; Rustema-Abbing, M; de Vries, Jacob; Busscher, HJ; van der Linden, M.L.; Hooymans, JMM; van der Mei, HC

    2003-01-01

    The aim of this study is to determine rigid gas permeable (RGP) lens surface properties prior to and after wear that are influential on adhesion of Pseudomonas aeruginosa. After 10 and 50 days of wear and after end-stage use, lenses were collected for determination of physico-chemical surface proper

  10. Dispersive surface properties of glass-ionomer cements determined by inverse gas chromatography

    Science.gov (United States)

    Andrzejewska, E.; Voelkel, A.; Andrzejewski, M.; Limanowska-Shaw, H.

    2005-05-01

    The surface properties of several glass-ionomer cements (GIC), restorative dental materials, (GC-Fuji, Chemadent G-J, Ketac Fil and Ketac Molar) were investigated for the first time by means of inverse gas chromatography. This method enables characterization of surface activity in dispersive (non-polar) and acid-base interactions. The ability of the surface of glass-ionomers to participate in dispersive interactions was expressed by the use of the dispersive component of surface free energy γsd. This parameter was determined with satisfactory precision, meaning that the values of γsd can be further used in the discussion of the influence of the type of GIC, its preparation and the storage time on the surface properties. The greatest capacity for dispersive interactions was revealed by Ketac Molar and the lowest by GC-Fuji. Dispersive interactions in the surface activity of glass-ionomers increased with increasing storage time after cement preparation.

  11. Reaction Kinetic Parameters and Surface Thermodynamic Properties of Cu2O Nanocubes

    Directory of Open Access Journals (Sweden)

    Xingxing Li

    2015-07-01

    Full Text Available Cuprous oxide (Cu2O nanocubes were synthesized by reducing Cu(OH2 in the presence of sodium citrate at room temperature. The samples were characterized in detail by field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray powder diffraction, and N2 absorption (BET specific surface area. The equations for acquiring reaction kinetic parameters and surface thermodynamic properties of Cu2O nanocubes were deduced by establishment of the relations between thermodynamic functions of Cu2O nanocubes and these of the bulk Cu2O. Combined with thermochemical cycle, transition state theory, basic theory of chemical thermodynamics, and in situ microcalorimetry, reaction kinetic parameters, specific surface enthalpy, specific surface Gibbs free energy, and specific surface entropy of Cu2O nanocubes were successfully determined. We also introduced a universal route for gaining reaction kinetic parameters and surface thermodynamic properties of nanomaterials.

  12. Radiative properties of magnetic neutron stars with metallic surfaces and thin atmospheres

    CERN Document Server

    Potekhin, A Y; van Adelsberg, M; Werner, K

    2012-01-01

    The goal of this work is to develop a simple analytic description of the emission properties (spectrum and polarization) of the condensed, strongly magnetized surface of neutron stars. We have improved the method of van Adelsberg et al. (2005) (arXiv:astro-ph/0406001) for calculating the spectral properties of condensed magnetized surfaces. Using the improved method, we calculate the reflectivity of an iron surface at magnetic field strengths B \\sim (10^{12} - 10^{14}) G, with various inclinations of the magnetic field lines and radiation beam with respect to the surface and each other. We construct analytic expressions for the emissivity of this surface as functions of the photon energy, magnetic field strength, and the three angles that determine the geometry of the local problem. Using these expressions, we calculate X-ray spectra for neutron stars with condensed iron surfaces covered by thin partially ionized hydrogen atmospheres. We develop simple analytic descriptions of the intensity and polarization o...

  13. IMPROVING THE SURFACE PROPERTY OF TC4 ALLOY BY LASER NITRIDING AND ITS MECHANISM

    Institute of Scientific and Technical Information of China (English)

    Y.L. Yang; G.J. Zhao; D. Zhang; C.S. Liu

    2006-01-01

    The mixing technology of laser and heated nitrogen was applied to improve the surface hardaccelerate the nitriding process. Some interested samples were tested with XRD method (X-ray diffraction) to analyze the composition of nitrides, and the surface hardness of HV was measured.The results show that TiN and Ti2N were formed on the surface of Ti alloy with proper nitriding parameters, but TiN is the main composition. The surface hardness increased by three times, which sidered mainly of the activation of nitrogen by laser power and the pre-heated process which accelerated the nitriding process. The nitridation process can be considered as six steps given in detail. The result by analyzing the mechanism of improving the surface property of TiAl alloy shows the improvement of surface property due to two factors: the first reason is the result of laser annealing, and the second one is the formation of TiN.

  14. Processing and properties of electrodeposited layered surface coatings

    DEFF Research Database (Denmark)

    Horsewell, Andy

    1998-01-01

    clacks and spalls off early on. For thick, non-compliant coatings, much thicker coatings can be formed. Fracture resistance must be considered in relation to both specimen and loading geometries. Since the inherent bending moment causes a maximum tensile stress at the coating surface, the loading......Hard chromium, produced by conventional dir ect curl ent (DC) electrodeposition, cannot be deposited to thicknesses gl enter than about 5 mu m because of the buildup of processing stresses which cause channel cracks in the coating. Much thicker chromium coatings map be produced by depositing...... a layered structure using alternate DC plating and periodic current reversal (PR). Such layering produces a through thickness stepped gradient in residual stresses. Most importantly a bending moment develops in the coating whenever the substrate is compliant. For thin, compliant substrates, the coating...

  15. Optical properties of Si nanoclusters with passivated surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, L.N. [Univ. of California, Davis, CA (United States). Dept. of Applied Science]|[Lawrence Livermore National Lab., CA (United States). Chemistry and Materials Science Dept.; Chase, L.L.; Balooch, M.; Siekhaus, W.J. [Lawrence Livermore National Lab., CA (United States). Chemistry and Material Science Dept.; Wooten, F. [Univ. of California, Davis, CA (United States). Dept. of Applied Science

    1996-12-31

    Si nanoclusters with average size of a few nanometers have been synthesized by thermal vaporization of Si in an Ar buffer gas, and passivated with oxygen or atomic hydrogen. High resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) revealed that these nanoclusters were crystalline. All samples showed strong infrared and/or visible photoluminescence (PL) with varying decay times form nanoseconds to microseconds depending on synthesis conditions. Absorption mainly in the Si cores was observed by photoluminescence excitation (PLE) spectroscopy. The visible components of PL spectra were noted to blue shift and broaden as the size of the Si nanocrystals (nc-Si) was reduced, and there were differences in PL spectra for hydrogen and oxygen passivated nc-Si. This data can be explained best by a model involving absorption between quantum confined states in the Si cores and emission by surface/interface states.

  16. Comparison of near surface and column-integrated atmospheric aerosol optical properties

    Science.gov (United States)

    Aryal, Rudra Prasad

    Optical and chemical properties of size-resolved aerosols in near-surface air at Tudor Hill, Bermuda were measured between July 2006 and June 2009. Vertical distributions of aerosol backscattering and column-averaged aerosol optical properties were characterized with a Micro-pulse lidar (MPL) and a CIMEL automated sun-sky radiometer. The chemical species in size-segregated aerosols in marine air were compared with the surface level aerosol optical properties. The aerosol concentration, along with chemical components, was compared with the surface level wind speed and showed a significant correlation with the sea salt components. The non-sea salt components such as non-sea salt sulfate and ammonium did not show a correlation with the surface level wind speed. A comparison between scattering data at surface level with the extinction coefficient at the lowest altitude bin (75m) from the lidar inversion shows a consistent correlation but is quantitatively different. This quantitative discrepancy was explained based on the hygroscopic growth due to differences in relative humidity in measurement conditions. Aerosol optical properties measured near the surface were often significantly correlated with those averaged over the column. These include scattering by near-surface bulk aerosol at 530 nm versus column aerosol optical depth (AOD), near-surface sub-microm scattering fraction versus column averaged sub-microm scattering fraction, and the average angstrom exponent over column and lidar ratio derived using column integrated size distribution and complex refractive index. We also found that the single scattering albedo (ω o) measured at the surface by combining daily averages of the aerosol absorption and aerosol light scattering were in the same range as the instantaneous ω o retrieved for the column. The relative contribution of submicron aerosol light scattering to total aerosol light scattering is slightly higher in the column relative to the surface. Surface

  17. Transient motion of and heat transfer in a rarefied gas between plane parallel walls with different surface properties

    Science.gov (United States)

    Doi, Toshiyuki

    2016-09-01

    Transient motion of and heat transfer in a rarefied gas between plane parallel walls with different surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary, and the transient behavior of the gas caused by a sudden heating of one of the walls is studied. The linearized Boltzmann equation for a hard-sphere molecular gas is numerically studied using the modified hybrid scheme of the characteristic coordinate and finite difference methods, to correctly describe the discontinuities in the velocity distribution function. The transient motion of the gas from an early time stage to the final time-independent state is studied over a wide range of the mean free path and the accommodation coefficient of the boundary. Between the two transient flows caused by the heating of the respective walls, the values of the heat flow on the heated wall are different, whereas those on the unheated wall coincide identically. This property, which is a consequence of the symmetric relation of the linearized Boltzmann equation, is numerically confirmed over a wide range of the mean free path. The long time behavior of the heat flow on the walls is quite similar to that of the shear stress in the Couette flow problem, whereas a distinct wavy behavior is observed in an early time stage.

  18. Irradiation of poly(tetrafluoroethylene) surfaces by CF4 plasma to achieve robust superhydrophobic and enhanced oleophilic properties for biological applications.

    Science.gov (United States)

    Salapare, Hernando S; Suarez, Beverly Anne T; Cosiñero, Hannah Shamina O; Bacaoco, Miguel Y; Ramos, Henry J

    2015-01-01

    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.

  19. Corresponding-states principle and its practice thermodynamic, transport and surface properties of fluids

    CERN Document Server

    Xiang, Hong Wei

    2005-01-01

    The corresponding-states principle helps the understanding and calculating of thermodynamic, transport, and surface properties of substances in various states, required by our modern lifestyle. The Corresponding-States Principle and its Practice: Thermodynamic, Transport and Surface Properties of Fluids describes the origins and applications of the principle from a universal point of view with comparisons to experimental data where possible. It uses the universal theory to explain present theories. Emphasis is on the properties of pure systems, and the corresponding-states theory can also be e

  20. Surface and transport properties of Cu-Sn-Ti liquid alloys

    Institute of Scientific and Technical Information of China (English)

    R. Novakovic; E. Ricci; S. Amore; T. Lanata

    2006-01-01

    The lack of experimental data and / or limited experimental information concerning both surface and transport properties of liquid alloys often require the prediction of these quantities. An attempt has been made to link the thermophysical properties of a ternary Cu-Sn-Ti system and its binary Cu-Sn, Cu-Ti and Sn-Ti subsystems with the bulk through the study of the concentration dependence of various thermodynamic, structural, surface and dynamic properties in the frame of the statistical mechanical theory in conjunction with the quasi-lattce theory (QLT). This formalism provides valuable qualitative insight into mixing processes that occur in molten alloys.

  1. Effects of surface wettability and roughness of microchannel on flow behaviors of thermo-responsive microspheres therein during the phase transition.

    Science.gov (United States)

    Zhou, Ming-Yu; Xie, Rui; Yu, Ya-Lan; Chen, Gang; Ju, Xiao-Jie; Yang, Lihua; Liang, Bin; Chu, Liang-Yin

    2009-08-01

    The flow characteristics of monodisperse thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) microspheres during the phase transition in microchannels with different surface wettabilities and roughnesses are investigated systematically. Glass microchannels are modified by hydroxylation treatment to achieve hydrophilic surface, by self-assembly of chlorotrimethylsilane to realize hydrophobic surface, and by coating with silica nanoparticles to generate rough surface. The phase transition of PNIPAM microspheres in microchannels is induced by local heating. The results show that the surface wettability and roughness of microchannel significantly affect the flow behaviors of PNIPAM microspheres during the phase transition. It is much easier for the PNIPAM microspheres in microchannel with hydrophobic surface to stop right after the phase transition than those in microchannel with hydrophilic surface, and it is also much easier for the PNIPAM microspheres in microchannel with rough surface to stop right after the phase transition than those in microchannel with smooth surface. These results indicate that hydrophobic and rough surface properties of the microchannel can enhance the site-specific targeting of PNIPAM microspheres caused by the phase transition. The results in this study provide valuable information for the application of thermo-responsive drug carriers in site-specific targeting therapy.

  2. Effect of surface topographic features on the optical properties of skin: a phantom study

    Science.gov (United States)

    Liu, Guangli; Chen, Jianfeng; Zhao, Zuhua; Zhao, Gang; Dong, Erbao; Chu, Jiaru; Xu, Ronald X.

    2016-10-01

    Tissue-simulating phantoms are used to validate and calibrate optical imaging systems and to understand light transport in biological tissue. Light propagation in a strongly turbid medium such as skin tissue experiences multiple scattering and diffuse reflection from the surface. Surface roughness introduces phase shifts and optical path length differences for light which is scattered within the skin tissue and reflected from the surface. In this paper, we study the effect of mismatched surface roughness on optical measurement and subsequent determination of optical properties of skin tissue. A series of phantoms with controlled surface features and optical properties corresponding to normal human skin are fabricated. The fabrication of polydimethylsiloxane (PDMS) phantoms with known surface roughness follows a standard soft lithography process. Surface roughness of skin-simulating phantoms are measured with Bruker stylus profiler. The diffuse reflectance of the phantom is validated by a UV/VIS spectrophotometer. The results show that surface texture and roughness have considerable influence on the optical characteristics of skin. This study suggests that surface roughness should be considered as an important contributing factor for the determination of tissue optical properties.

  3. Electrical transport properties of graphene on SiO2 with specific surface structures

    OpenAIRE

    Nagashio, K.; Yamashita, T; Nishimura, T.; K. Kita; Toriumi, A.

    2011-01-01

    The mobility of graphene transferred on a SiO2/Si substrate is limited to ~10,000 cm2/Vs. Without understanding the graphene/SiO2 interaction, it is difficult to improve the electrical transport properties. Although surface structures on SiO2 such as silanol and siloxane groups are recognized, the relation between the surface treatment of SiO2 and graphene characteristics has not yet been elucidated. This paper discusses the electrical transport properties of graphene on specific surface stru...

  4. Surface fractal dimensions and textural properties of mesoporous alkaline-earth hydroxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Vilchis-Granados, J. [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico); Granados-Correa, F., E-mail: francisco.granados@inin.gob.mx [Instituto Nacional de Investigaciones Nucleares, Departamento de Química, A.P. 18-1027, Col. Escandón, Delegación Miguel Hidalgo, C.P. 11801, México, DF (Mexico); Barrera-Díaz, C.E. [Universidad Autónoma del Estado de México, Facultad de Química, Av. Paseo Colón esquina con Paseo Tollocan s/n Toluca, México (Mexico)

    2013-08-15

    This work examines the surface fractal dimensions (D{sub f}) and textural properties of three different alkaline-earth hydroxyapatites. Calcium, strontium and barium hydroxyapatite compounds were successfully synthesized via chemical precipitation method and characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy, and N{sub 2}-physisorption measurements. Surface fractal dimensions were determined using single N{sub 2}-adsorption/desorption isotherms method to quantify the irregular surface of as-prepared compounds. The obtained materials were also characterized through their surface hydroxyl group content, determined by the mass titration method. It was found that the D{sub f} values for the three materials covered the range of 0.77 ± 0.04–2.33 ± 0.11; these results indicated that the materials tend to have smooth surfaces, except the irregular surface of barium hydroxyapatite. Moreover, regarding the synthesized calcium hydroxyapatite exhibited better textural properties compared with the synthesized strontium and barium hydroxyapatites for adsorbent purposes. However, barium hydroxyapatite shows irregular surface, indicating a high population of active sites across the surface, in comparison with the others studied hydroxyapatites. Finally, the results showed a linear correlation between the surface hydroxyl group content at the external surface of materials and their surface fractal dimensions.

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

    Directory of Open Access Journals (Sweden)

    Chen Peijian

    2014-06-01

    Full Text Available 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 simultaneously considered in the generalized model. It is found that proper interfacial strength can be controlled by adjusting surface roughness σ / R, graded exponent k and material parameter E*R / Δγ. The results should be helpful in the design of new biomimetic materials and useful in application of micro functional instruments.

  6. Dynamic behavior of water droplets on solid surfaces with pillar-type nanostructures.

    Science.gov (United States)

    Jeong, Woog-Jin; Ha, Man Yeong; Yoon, Hyun Sik; Ambrosia, Matthew

    2012-03-27

    In the present study, we investigated the static and dynamic behavior of water droplets on solid surfaces featuring pillar-type nanostructures by using molecular dynamics simulations. We carried out the computation in two stages. As a result of the first computational stage, an initial water cube reached an equilibrium state at which the water droplet showed different shapes depending on the height and the lateral and gap dimensions of the pillars. In the second computational stage, we applied a constant body force to the static water droplet obtained from the first computational stage and evaluated the dynamic behavior of the water droplet as it slid along the pillar-type surface. The dynamic behavior of the water droplet, which could be classified into three different groups, depended on the static state of the water droplet, the pillar characteristics (e.g., height and the lateral and gap dimensions of the pillars), and the magnitude of the applied body force. We obtained the advancing and receding contact angles and the corresponding contact angle hysteresis of the water droplets, which helped classify the water droplets into the three different groups.

  7. Bioactive titanium metal surfaces with antimicrobial properties prepared by anodic oxidation treatment

    Institute of Scientific and Technical Information of China (English)

    YUE ChongXia; YANG BangCheng; ZHANG XingDong

    2009-01-01

    In order to endow titanium metals with bioactivity and antimicrobial properties,titanium plates were subjected to anodic oxidation treatment in NaCI solutions in this study.The treated titanium metals could induce apatite formation in the fast calcification solution,and osteoblasts on the treated titanium surfaces proliferated well as those on the untreated titanium metal surfaces.The treated metals could inhibit S.aureus growth in the microbial culture experiments.It was assumed that Ti-OH groups and Ti-CI groups formed on the treated titanium surface were responsible for the bioactivity and antimicrobial properties of the metals.The anodic oxidation treatment was an effective way to prepare bioactive titanium surfaces with antimicrobial properties.

  8. Surface radiation properties of ThO/sub 2/ and other reactor materials

    Energy Technology Data Exchange (ETDEWEB)

    Chan, S.H.; Ma, H.H.

    1979-12-01

    This technical report summarizes the results obtained on surface radiation properties of ThO/sub 2/ and other related reactor materials. Specifically, the present study provides surface radiation properties of three nuclear reactor materials; thorium dioxide, sodium and steel (99 Fe + 1 C). First, based on transmission spectra and Kramers-Kronig analysis, the complex refractive index, which is fundamental to surface radiation property calculations, of ThO/sub 2/ is presented over a wide spectral range. Then depending on the contacting media, three types of the surface are considered. They are the interfaces between ThO/sub 2/ and Sodium, ThO/sub 2/ and Steel (99 Fe + 1 C) as well as ThO/sub 2/ and a gas. For each interface, the spectral interface reflectance from one side of the medium to the other side is evaluated for all wavelengths.

  9. Formation and tribology properties of polyfluoroal-kylmethacrylate film on the magnetic head surface

    Institute of Scientific and Technical Information of China (English)

    HU Xiaoli; ZHANG Chenhui; LUO Jianbin; WEN Shizhu

    2005-01-01

    A polyfluoroalkylmethacrylate (PFAM) film has been coated on the surface of the magnetic head by a dipping coating method to modify the surface properties. The films were characterized by means of a time-of-flight secondary ion mass spectrometer (TOF-SIMS), contact angle measurement and atomic force microscopy (AFM). The results indicate that the concentration of the solution is the main factor affecting the thickness, contact angle and surface topography of the film. The magnetic head with the PFAM film at a concentration of 500 ppm exhibits the best tribology properties, and the stiction between the magnetic head and the disk is no more than 2.4 g after 20000 contact start stop (CSS) cycles. Therefore, a fully covered PFAM film with few defects helps improve the tribology properties of the magnetic head, and decrease the adsorbed contaminant on the magnetic head surface.

  10. Synthesis, Surface Active Properties and Cytotoxicity of Sodium N-Acyl Prolines.

    Science.gov (United States)

    Sreenu, Madhumanchi; Narayana Prasad, Rachapudi Badari; Sujitha, Pombala; Kumar, Chityal Ganesh

    2015-01-01

    Sodium N-acyl prolines (NaNAPro) were synthesized using mixture of fatty acids obtained from coconut, palm, karanja, Sterculia foetida and high oleic sunflower oils via Schotten-Baumann reaction in 58-75% yields to study the synergetic effect of mixture of hydrophobic fatty acyl functionalities like saturation, unsaturation and cyclopropene fatty acids with different chain lengths and aliphatic hetero cyclic proline head group on their surface and cytotoxicity activities. The products were characterized by chromatographic and spectral techniques. The synthesized products were evaluated for their surface active properties such as surface tension, wetting power, foaming characteristics, emulsion stability, calcium tolerance, critical micelle concentration (CMC) and thermodynamic properties. The results revealed that all the products exhibited superior surface active properties like CMC, calcium tolerance and emulsion stability as compared to the standard surfactant, sodium lauryl sulphate (SLS). In addition, palm, Sterculia foetida and high oleic sunflower fatty N-acyl prolines exhibited promising cytotoxicity against different tumor cell lines.

  11. Tensile Properties of Surface-Treated Glass Fiber Reinforced PTFE Composite with Rare Earth Elements

    Institute of Scientific and Technical Information of China (English)

    薛玉君; 程先华

    2003-01-01

    The optimum amount of rare earth elements (RE) for treating glass fiber surface and its effect on the tensile properties of glass fiber reinforced polytetrafluoroethylene (GF/PTFE) composites were investigated. The tensile properties of GF/PTFE composites with different surface treatment conditions were measured. The fracture surface morphologies were observed and analyzed by SEM. The results indicate that rare earth elements can effectively promote the interfacial adhesion between the glass fiber and PTFE, owing to the effects of rare earth elements on the compatibility. The tensile properties of GF/PTFE composites can be improved considerably when the content of RE in surface modifier is 0.2%~0.4%, and the optimum performance of GF/PTFE composites is obtained at 0.3%RE content.

  12. Surface structure and properties of plant seed oil bodies.

    Science.gov (United States)

    Tzen, J T; Huang, A H

    1992-04-01

    Storage triacylglycerols (TAG) in plant seeds are present in small discrete intracellular organelles called oil bodies. An oil body has a matrix of TAG, which is surrounded by phospholipids (PL) and alkaline proteins, termed oleosins. Oil bodies isolated from mature maize (Zea mays) embryos maintained their discreteness, but coalesced after treatment with trypsin but not with phospholipase A2 or C. Phospholipase A2 or C exerted its activity on oil bodies only after the exposed portion of oleosins had been removed by trypsin. Attempts were made to reconstitute oil bodies from their constituents. TAG, either extracted from oil bodies or of a 1:2 molar mixture of triolein and trilinolein, in a dilute buffer were sonicated to produce droplets of sizes similar to those of oil bodies; these droplets were unstable and coalesced rapidly. Addition of oil body PL or dioleoyl phosphatidylcholine, with or without charged stearylamine/stearic acid, or oleosins, to the medium before sonication provided limited stabilization effects to the TAG droplets. High stability was achieved only when the TAG were sonicated with both oil body PL (or dioleoyl phosphatidylcholine) and oleosins of proportions similar to or higher than those in the native oil bodies. These stabilized droplets were similar to the isolated oil bodies in chemical properties, and can be considered as reconstituted oil bodies. Reconstituted oil bodies were also produced from TAG of a 1:2 molar mixture of triolein and trilinolein, dioleoyl phosphatidylcholine, and oleosins from rice (Oryza sativa), wheat (Triticum aestivum), rapeseed (Brassica napus), soybean (Glycine max), or jojoba (Simmondsia chinensis). It is concluded that both oleosins and PL are required to stabilize the oil bodies and that oleosins prevent oil bodies from coalescing by providing steric hindrance. A structural model of an oil body is presented. The current findings on seed oil bodies could be extended to the intracellular storage lipid

  13. Chemical and mechanical properties of surfaces on the nanoscale

    Science.gov (United States)

    Broz, Margaret Elizabeth

    This research investigated the chemical and physical properties of materials on the nanoscale. Combinatorial atomic layer deposition was used to deposit conformal films with compositional gradients from 100% aluminum oxide to 100% zinc oxide. The films were characterized using ellipsometry, scanning electron microscopy and Auger electron spectroscopy to determine their thickness and composition, respectively. Atomic layer deposition was confirmed individually for aluminum oxide and zinc oxide. Combinatorial experiments confirmed the etching of ZnO by the trimethyl aluminum precursor, which was compensated for by adjusting the pulse sequence. Thin diamond-like carbon films were studied using scanning probe microscopy techniques (atomic force microscopy, friction force microscopy, digital pulsed force mode atomic force microscopy) and a method for quantifying the friction coefficient of these films was refined. Friction forces and the friction coefficient were measured for diamond-like carbon films over a range of relative humidity values and hysteresis effects were also studied. The adhesion changes due to fluorinated lubricant top coats on the diamond-like carbon were studied using digital pulsed force mode atomic force microscopy over a range of relative humidity values. Special diamond-like carbon coated tips were used in both sets of experiments to simulate the head-disk interaction between the slider and media in hard disk drive systems. Monodisperse oleic acid-capped lead selenide nanocrystals were synthesized using a modified hot injection method. Size-tunable nanocrystals were obtained by adjusting synthetic parameters. Nanocrystals were analyzed using X-ray diffraction, absorbance spectroscopy and UV-Visible spectroscopy. Organic ligands were also synthesized and used in ligand exchange experiments. Drop cast films of the nanocrystals with new ligands showed some change in FTIR peak position.

  14. Surface and Wetting Properties of Embiopteran (Webspinner) Nanofiber Silk.

    Science.gov (United States)

    Osborn Popp, Thomas M; Addison, J Bennett; Jordan, Jacob S; Damle, Viraj G; Rykaczewski, Konrad; Chang, Shery L Y; Stokes, Grace Y; Edgerly, Janice S; Yarger, Jeffery L

    2016-05-10

    Insects of the order Embioptera, known as embiopterans, embiids, or webspinners, weave silk fibers together into sheets to make shelters called galleries. In this study, we show that silk galleries produced by the embiopteran Antipaluria urichi exhibit a highly hydrophobic wetting state with high water adhesion macroscopically equivalent to the rose petal effect. Specifically, the silk sheets have advancing contact angles above 150°, but receding contact angle approaching 0°. The silk sheets consist of layered fiber bundles with single strands spaced by microscale gaps. Scanning and transmission electron microscopy (SEM, TEM) images of silk treated with organic solvent and gas chromatography mass spectrometry (GC-MS) of the organic extract support the presence of a lipid outer layer on the silk fibers. We use cryogenic SEM to demonstrate that water drops reside on only the first layer of the silk fibers. The area fraction of this sparse outer silk layers is 0.1 to 0.3, which according to the Cassie-Baxter equation yields an effective static contact angle of ∼130° even for a mildly hydrophobic lipid coating. Using high magnification optical imaging of the three phase contact line of a water droplet receding from the silk sheet, we show that the high adhesion of the drop stems from water pinning along bundles of multiple silk fibers. The bundles likely form when the drop contact line is pinned on individual fibers and pulls them together as it recedes. The dynamic reorganization of the silk sheets during the droplet movement leads to formation of "super-pinning sites" that give embiopteran silk one of the strongest adhesions to water of any natural hydrophobic surface.

  15. A Study on the Surface Oxidation Behavior of Cube-textured Nickel Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Ji Hyun; Kim, Byeong Joo; Kim, Jae Geun; Kim, Ho Jin; Hong, Gye Won; Lee, Hee Gyoun [Korea Polytechnic University, Siheung (Korea, Republic of); Yoo, Jai Moo [Korea Instititue of Machinery and Matrials, Changwon (Korea, Republic of); Pradeep, Halder [College of Namoscale Science and Engineering, University at Albany, State University of NewYork, Albany (United States)

    2005-10-15

    We investigated the surface oxidation behavior of cube-textured polycrystalline nickel at various oxidation conditions. Cube-textured NiO film was formed on a cube-textured polycrystalline nickel regardless of oxidation conditions but different growth behavior of NiO crystals was observed depending on the oxidation conditions. The introduction of water vapor into O{sub 2} did not affect the texture evolution, but rough and porous microstructure was developed. Microstructure of NiO film tends to be denser as the oxygen partial pressure increases. It is interesting that peak of theta - two theta diffraction pattern started to get stronger in air atmosphere and plane became the major texture in the substrate oxidized in high purity argon gas. Small amount of high index crystallographic plane NiO peak crystal was observed when N{sub 2}Owas used as an oxidant while only plane crystal was formed in dry O{sub 2} atmosphere. Flat and smooth surface was changed into rough faceted one when ramping rate to oxidation temperature was faster. The grain size of NiO was decreased when the oxygen partial pressure was low. It was also observed that the modification of nickel surface suppressed the development of texture.

  16. Colonization of Bacteria on the Surfaces of Cold-Sprayed Copper Coatings Alters Their Electrochemical Behaviors

    Science.gov (United States)

    Suo, Xinkun; Abdoli, Leila; Liu, Yi; Xia, Peng; Yang, Guanjun; Li, Hua

    2017-02-01

    Copper coatings were fabricated on stainless steel plates by cold spraying. Attachment and colonization of Bacillus sp. on their surfaces in artificial seawater were characterized, and their effects on anticorrosion performances of the coatings were examined. Attached bacteria were observed using field emission scanning electron microscopy. Electrochemical behaviors including potentiodynamic polarization and electrochemical impedance spectroscopy with/without bacterial attachment were evaluated using commercial electrochemical analysis station Modulab. Results show that Bacillus sp. opt to settle on low-lying spots of the coating surfaces in early stage, followed by recruitment and attachment of extracellular polymeric substances (EPS) secreted through metabolism of Bacillus sp. The bacteria survive with the protection of EPS. An attachment model is proposed to illustrate the bacterial behaviors on the surfaces of the coatings. Electrochemical data show that current density under Bacillus sp. environment decreases compared to that without the bacteria. Charge-transfer resistance increases markedly in bacteria-containing seawater, suggesting that corrosion resistance increases and corrosion rate decreases. The influencing mechanism of bacteria settlement on corrosion resistance of the cold-sprayed copper coatings was discussed and elucidated.

  17. Influence of thermal and surface effects on vibration behavior of nonlocal rotating Timoshenko nanobeam

    Science.gov (United States)

    Ghadiri, Majid; Shafiei, Navvab; Akbarshahi, Amir

    2016-07-01

    This paper is proposed to study the free vibration of a rotating Timoshenko nanobeam based on the nonlocal theory considering thermal and surface elasticity effects. The governing equations and the related boundary conditions are derived using the Hamilton's principle. In order to solve the problem, generalized differential quadrature method is applied to discretize the governing differential equations corresponding to clamped-simply and clamped-free boundary conditions. In this article, the influences of some parameters such as nonlocal parameter, angular velocity, thickness of the nanobeam, and thermal and surface elasticity effects on the free vibration of the rotating nanobeam are investigated, and the results are compared for different boundary conditions. The results show that the surface effect and the nonlocal parameter and the temperature changes have significant roles, and they should not be ignored in the vibrational study of rotating nanobeams. Also, the angular velocity and the hub radius have more significant roles than temperature change effects on the nondimensional frequency. It is found that the nonlocal parameter behavior and the temperature change behavior on the frequency are different in the first mode for the rotating cantilever nanobeam.

  18. Effect of Surface Densification on the Microstructure and Mechanical Properties of Powder Metallurgical Gears by Using a Surface Rolling Process

    Directory of Open Access Journals (Sweden)

    Jingguang Peng

    2016-10-01

    Full Text Available Powder metallurgy (PM components are widely used in the auto industry due to the advantage of net-shape forming, low cost, and high efficiency. Still, usage of PM components is limited in the auto industry when encountering rigorous situations, like heavy load, due to lower strength, hardness, wear resistance, and other properties compared to wrought components due to the existence of massive pores in the PM components. In this study, through combining the powder metallurgy process and rolling process, the pores in the PM components were decreased and a homogenous densified layer was formed on the surface, which resulted in the enhancement of the strength, hardness, wear resistance, and other properties, which can expand its range of application. In this paper, we study the impact of different rolling feeds on the performance of the components’ surfaces. We found that with the increase of the rolling feed, the depth of the densified layer increased.

  19. Organic fouling behavior of superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membranes functionalized with surface-tailored nanoparticles: Implications for organic fouling in membrane bioreactors

    KAUST Repository

    Liang, Shuai

    2014-08-01

    This study systematically investigates the organic fouling behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly(methacrylic acid)-grafted PVDF membrane surface. Sodium alginate (SA), Suwannee River natural organic matter (SRNOM), and bovine serum albumin (BSA) were used as model organic foulants to investigate the antifouling behavior of the superhydrophilic membrane with combined-fouling (mixture of foulants) and individual-fouling (single foulant) tests. A membrane bioreactor (MBR) plant supernatant was also used to verify the organic antifouling property of the superhydrophilic membrane under realistic conditions. Foulant size distributions and foulant-membrane interfacial forces were measured to interpret the observed membrane fouling behavior. Molecular weight cutoff measurements confirmed that membrane functionalization did not adversely affect the intrinsic membrane selectivity. Both filtration tests with the synthetic foulant-mixture solution (containing SA, SRNOM, and BSA) and MBR plant supernatant demonstrated the reliability and durability of the antifouling property of the superhydrophilic membrane. The conspicuous reduction in foulant-membrane interfacial forces for the functionalized membrane further verified the antifouling properties of the superhydrophilic membrane, suggesting great potential for applications in wastewater treatment. © 2014 Elsevier B.V.

  20. Surface modification by plasma polymerization: film deposition, tailoring of surface properties and biocompatibility

    NARCIS (Netherlands)

    Os, van Menno Thomas

    2000-01-01

    The work described in this thesis concerns the surface modification of materials by thin film deposition in a plasma reactor. In particular, thin polymeric films bearing amine functionalities were synthesized by plasma polymerization of amino group containing monomers. In addition to the synthesis,

  1. A Modeling Study of Land Surface Process Impacts on Inland Behavior of Typhoon Rananim (2004)

    Institute of Scientific and Technical Information of China (English)

    WEI Na; LI Ying

    2013-01-01

    On 12 August 2004,Typhoon Rananim (0414) moved inland over China and stagnated over the Poyang Lake area,resulting in torrential rainfall and severe geologic hazards.The Advanced Weather Research and Forecasting (ARW-WRF) model and its different land surface models (LSMs) were employed to study the impacts of land surface process on the inland behavior of Typhoon Rananim.Results show that simulations,coupled with LSMs or not,have no significant differences in predicting typhoon track,intensity,and largescale circulation.However,the simulations of mesoscale structure,rainfall rate,and rainfall distribution of typhoon are more reasonable with LSMs than without LSMs.Although differences are slight among LSMs,NOAH is better than the others.Based on outputs using the NOAH scheme,the interaction between land surface and typhoon was explored in this study.Notably,typhoon rainfall and cloud cover can cool land surface,but rainfall expands the underlying saturated wetland area,which exacerbates the asymmetric distribution of surface heat fluxes.Accordingly,an energy frontal zone may form in the lower troposphere that enhances ascending motion and local convection,resulting in heavier rainfall.Moreover,the expanded underlying saturated wetlands provide plentiful moisture and unstable energy for the maintenance of Typhoon Rananim and increased rainfall in return.

  2. Observation of adsorption behavior of biomolecules on ferroelectric crystal surfaces with polarization domain patterns

    Science.gov (United States)

    Nakayama, Tomoaki; Isobe, Akiko; Ogino, Toshio

    2016-08-01

    Lithium tantalate (LiTaO3) is one of the ferroelectric crystals that exhibit spontaneous polarization domain patterns on its surface. We observed the polarization-dependent adsorption of avidin molecules, which are positively charged in a buffer solution at pH 7.0, on LiTaO3 surfaces caused by electrostatic interaction at an electrostatic double layer using atomic force microscopy (AFM). Avidin adsorption in the buffer solution was confirmed by scratching the substrate surfaces using the AFM cantilever, and the adsorption patterns were found to depend on the avidin concentration. When KCl was added to the buffer solution to weaken the electrostatic double layer interaction between avidin molecules and LiTaO3 surfaces, adsorption domain patterns disappeared. From the comparison between the adsorption and chemically etched domain patterns, it was found that avidin molecule adsorption is enhanced on negatively polarized domains, indicating that surface polarization should be taken into account in observing biomolecule behaviors on ferroelectric crystals.

  3. The influence of surface functionalisation on the electrical properties and thermal stability of nanodiamonds

    Energy Technology Data Exchange (ETDEWEB)

    Welch, Joseph O; Li, Pei; Chaudhary, Aysha; Edgington, Robert; Jackman, Richard B., E-mail: r.jackman@ucl.ac.uk [London Centre for Nanotechnology and the Department of Electronic and Electrical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH (United Kingdom)

    2014-10-07

    Detonation nanodiamond (ND) has recently emerged as a useful new class of diamond material. However, to date there has been little investigation of the electrical properties of this material. Due to the nanoscale dimensions, the surface functionalisation of the individual ND is of particular importance to the characteristics of ND films. Here, hydrogen and oxygen termination of ND, verified using Fourier transform infrared spectroscopy, are shown to strongly influence the electronic properties of NDs. Hydrogen terminated ND exhibiting a far greater resilience to thermal decomposition when compared to the oxygen terminated NDs. Moreover, H-NDs also displayed so-called “surface conductivity,” a property displayed by hydrogen-terminated bulk diamond films, whilst O-NDs display properties high resistivity. These results indicate that under the correct conditions ND layers can display similar electrical properties to “bulk” diamond thin films.

  4. The influence of surface functionalisation on the electrical properties and thermal stability of nanodiamonds

    Science.gov (United States)

    Welch, Joseph O.; Li, Pei; Chaudhary, Aysha; Edgington, Robert; Jackman, Richard B.

    2014-10-01

    Detonation nanodiamond (ND) has recently emerged as a useful new class of diamond material. However, to date there has been little investigation of the electrical properties of this material. Due to the nanoscale dimensions, the surface functionalisation of the individual ND is of particular importance to the characteristics of ND films. Here, hydrogen and oxygen termination of ND, verified using Fourier transform infrared spectroscopy, are shown to strongly influence the electronic properties of NDs. Hydrogen terminated ND exhibiting a far greater resilience to thermal decomposition when compared to the oxygen terminated NDs. Moreover, H-NDs also displayed so-called "surface conductivity," a property displayed by hydrogen-terminated bulk diamond films, whilst O-NDs display properties high resistivity. These results indicate that under the correct conditions ND layers can display similar electrical properties to "bulk" diamond thin films.

  5. Adsorption behavior of oxidized galactomannans onto amino terminated surfaces and their interaction with bovine serum albumin

    Energy Technology Data Exchange (ETDEWEB)

    Sierakowski, M.-R; Silva, Maria R.V. da [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Quimica. Lab. de Biopolimeros]. E-mail: mrbiopol@quimica.ufpr.br; Freitas, R.A.; Moreira, Jose S.R. [Universidade Federal do Parana, Curitiba, PR (Brazil). Dept. de Bioquimica; Fujimoto, J.; Petri, D.F.S.; Cordeiro, Paulo R.D. [Sao Paulo Univ., SP (Brazil). Inst. de Quimica]. E-mail: dfsp@quim.iq.usp.br; Andrade, Fabiana D

    2001-07-01

    A galactomannan (CF) extracted from Cassia fastuosa seeds was purified and oxidized with (2,2,6,6- tetramethylpiperidine-1-oxyl) to form a uronic acid-containing polysaccharide (CFOX) with a degree of oxidation (DO) of 0.22. The chemical structures of CF and CFOX were characterized. The adsorption behavior of CF and CFOX onto amino-terminated surfaces was studied by means of ellipsometric measurements. The influence of p H and ionic strength on the adsorption was also investigated. At p H 4, there was a maximum in the adsorbed amount caused by strong electrostatic attraction between the substrate and the oxidized galactomannans. There was no ionic strength effect on the adsorption behavior. The immobilization of bovine serum albumin onto CF and CFOX was studied as a function of p H. At the isoelectric point a maximum in the adsorbed amount was found. (author)

  6. Surface effects of electrode-dependent switching behavior of resistive random-access memory

    KAUST Repository

    Ke, Jr Jian

    2016-09-26

    The surface effects of ZnO-based resistive random-access memory (ReRAM) were investigated using various electrodes. Pt electrodes were found to have better performance in terms of the device\\'s switching functionality. A thermodynamic model of the oxygen chemisorption process was proposed to explain this electrode-dependent switching behavior. The temperature-dependent switching voltage demonstrates that the ReRAM devices fabricated with Pt electrodes have a lower activation energy for the chemisorption process, resulting in a better resistive switching performance. These findings provide an in-depth understanding of electrode-dependent switching behaviors and can serve as design guidelines for future ReRAM devices.

  7. The effect of polyether functional polydimethylsiloxane on surface and thermal properties of waterborne polyurethane

    Science.gov (United States)

    Zheng, Guikai; Lu, Ming; Rui, Xiaoping

    2017-03-01

    Waterborne polyurethanes (WPU) modified with polyether functional polydimethylsiloxane (PDMS) were synthesized by pre-polymerization method using isophorone diisocyanate (IPDI) and 1,4-butanediol (BDO) as hard segments and polybutylene adipate glycol (PBA) and polyether functional PDMS as soft segments. The effect of polyether functional PDMS on phase separation, thermal properties, surface properties including surface composition, morphology and wettability were investigated by FTIR, contact angle measurements, ARXPS, SEM-EDS, AFM, TG and DSC. The results showed that the compatibility between urethane hard segment and PDMS modified with polyether was good, and there was no distinct phase separation in both bulk and surface of WPU films. The degradation temperature and low temperature flexibility increased with increasing amounts of polyether functional PDMS. The enrichment of polyether functional PDMS with low surface energy on the surface imparted excellent hydrophobicity to WPU films.

  8. Dual-layered-coated mechanically-durable superomniphobic surfaces with anti-smudge properties.

    Science.gov (United States)

    Muthiah, Palanikkumaran; Bhushan, Bharat; Yun, Kyungsung; Kondo, Hirofumi

    2013-11-01

    Bio-inspired surfaces that exhibit high contact angle and low contact angle hysteresis for various liquids and demonstrate mechanical durability and anti-smudge properties are of interest for various applications. The fabrication of such surfaces has often involved complex or expensive processes, required techniques that may not be suitable for various substrates and particles, may require surface post-treatment, or may lack durability. Dual layered coatings of roughness-induced superomniphobic surfaces that demonstrate good mechanical durability were fabricated on glass substrates using hydrophobic SiO2 nanoparticles and low surface energy fluorobinders using dip coating and spray coating techniques. The particle-to-binder ratio was optimized for contact angles of interest. The mechanical durability of these coatings was examined under mechanical rubbing action. The anti-smudge properties were examined by wiping an artificially contaminated coating using oil-impregnated microfiber cloth.

  9. Effect of chitosan and cationic starch on the surface chemistry properties of bagasse paper.

    Science.gov (United States)

    Ashori, Alireza; Cordeiro, Nereida; Faria, Marisa; Hamzeh, Yahya

    2013-07-01

    The use of non-wood fibers in the paper industry has been an economical and environmental necessity. The application of dry-strength agents has been a successful method to enhance the strength properties of paper. The experimental results evidencing the potential of chitosan and cationic starch utilization in bagasse paper subjected to hot water pre-extraction has been presented in this paper. The research analyzes the surface properties alterations due to these dry-strength agents. Inverse gas chromatography was used to evaluate the properties of surface chemistry of the papers namely the surface energy, active sites, surface area as well as the acidic/basic character. The results of the study revealed that the handsheets process causes surface arrangement and orientation of chemical groups, which induce a more hydrophobic and basic surface. The acid-base surface characteristics after the addition of dry-strength agents were the same as the bagasse handsheets with and without hot water pre-extraction. The results showed that the dry-strength agent acts as a protecting film or glaze on the surfaces of bagasse paper handsheets.

  10. Properties of human dentin surface after ArF excimer laser irradiation.

    Science.gov (United States)

    Ishida, Tomohiro; Tonami, Ken-ichi; Araki, Kouji; Kurosaki, Norimasa

    2008-03-01

    Recently, improvement of the properties of dentin surface using dental lasers to increase bonding strength has been anticipated in the field of adhesive dentistry. The objective of this study was to investigate changes in the surface properties of human dentin after ArF excimer laser irradiation at different irradiation times, pulse repetition rates and energy densities. The SEM images of the irradiated surfaces were observed, and the contact angle and the roughness of the irradiated surface were measured. As a result, SEM demonstrated that the dentin surface became irregular following ArF excimer laser irradiation. When the energy density increased, the irregularity became more minute and dentinal tubules were more easily identified. By contrast, such changes were not observed when the irradiation time and pulse repetition rate were changed. Moreover, as energy densities increased, the contact angle tended to decrease and the surface roughness tended to increase. These results suggested that the area of the irradiated surface and wettability increased after irradiation with the ArF excimer laser. Consequently, irradiation with ArF excimer lasers could improve the surface properties and be potentially useful for adhesive dentistry.

  11. The influence of surface finishing of Paulownia Siebold et Zucc. on the mechanical properties of lacquered surface

    Directory of Open Access Journals (Sweden)

    Jaić Milan

    2010-01-01

    Full Text Available This paper presents the research of influence of sanding, staining and the use of polyurethane and acrylic coating on the adhesion, scratch resistance and abrasion resistance of the coating. Objective was to determine the most important mechanical properties of lacquered surfaces, considering the application of Paulownia elongata and Paulownia fortunei, by using different systems of surface finishing. Cross cut method was used for measurement of adhesion. More accurate view of coating adhesion was obtained by measuring the scratch resistance. Abrasion resistance was tested by the method of free falling of abrasive particles. The applied system of sanding had no effect on the examined mechanical properties. Stained samples lacquered with PU coating showed better adhesion to the non-stained samples. Impact of staining on scratch resistance is not established. Stained samples showed greater resistance to abrasion for both wood species. Samples lacquered with PU coating showed the higher values of mechanical properties compared with samples lacquered with UV acrylic coating. Application of PU coating for surface finishing of Paulownia elongata and Paulownia fortunei is more adequate than the application of UV acrylic coatings, from the point of scratch resistance and abrasion resistance.

  12. Increased surfacing behavior in longnose killifish infected by brain-encysting trematode.

    Science.gov (United States)

    Fredensborg, B L; Longoria, A N

    2012-10-01

    Some parasites modify the behavior of intermediate hosts to increase the probability of transmission to the next host in their life cycle. In habitats where this is common, parasites play an important role in predator-prey links and food web dynamics. In this study we used laboratory observations to investigate the behavior of longnose killifish, Fundulus similis, that were naturally infected with metacercariae of the trematode, Euhaplorchis sp. A, from Laguna Madre, south Texas. In particular, we examined whether there was a relationship between the number of metacercariae lodged on the brain of the infected fish and behaviors that made the fish more conspicuous to avian final hosts. We also quantified the abundance and cercariae production of this parasite in its first intermediate snail host, Cerithidea pliculosa , and examined the seasonal variation of Euhaplorchis sp. A in F. similis . Our data demonstrated that Euhaplorchis sp. A affected the surfacing behavior of F. similis in an intensity-dependent manner. Fish with many infections spent longer time at the surface of the water than fish with few infections. Our data also show that Euhaplorchis sp. A is a common parasite in the first intermediate host and produces close to 4,000 cercariae m(-2) day(-1). Consequently 97% of all fish collected and necropsied were infected, with little seasonal variation in the mean abundance of the parasite. Based on our data, Euhaplorchis sp. A is likely important to predator-prey links in Gulf of Mexico estuary food webs, similar to the closely related Euhaplorchis californiensis in southern California. We expect that other closely related species elsewhere may have similar effects on other fish hosts, emphasizing the need for incorporating trophically transmitted parasites in estuarine food web studies.

  13. Surface charge properties of red mud particles generated from Chinese diaspore bauxite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kun-yu; HU Hui-ping; ZHANG Li-juan; CHEN Qi-yuan

    2008-01-01

    Acid/basic potentiometric titration can be used to quantify the red mud surface charge properties. The amount of surface active -OH groups and surface charge density on the red mud particles generated from Chinese diaspore bauxite were evaluated from the acid/basic potentiometric titration data in 0.1 mol/L or 0.5 molL NaCI solution. The results show that the adsorption of sodium polyacrylate(SPA) on the red mud surface causes the increase of the surface active -OH groups, which makes the point of zero charge(PZC) shift to a lower pH value. However, the adsorption of polyacrylamide(PAM) causes little change. As the concentration of NaCl solution increases, the surface charge becomes more positive in acidic solution and more negative in alkaline solution, which can be attributed to the presence of a porous surface gel coating on the red mud particles.

  14. Effect of Moisture Absorption Behavior on Mechanical Properties of Basalt Fibre Reinforced Polymer Matrix Composites

    Directory of Open Access Journals (Sweden)

    Amuthakkannan Pandian

    2014-01-01

    Full Text Available The study of mechanical properties of fibre reinforced polymeric materials under different environmental conditions is much important. This is because materials with superior ageing resistance can be satisfactorily durable. Moisture effects in fibre reinforced plastic composites have been widely studied. Basalt fibre reinforced unsaturated polyester resin composites were subjected to water immersion tests using both sea and normal water in order to study the effects of water absorption behavior on mechanical properties. Composites specimens containing woven basalt, short basalt, and alkaline and acid treated basalt fibres were prepared. Water absorption tests were conducted by immersing specimens in water at room temperature for different time periods till they reached their saturation state. The tensile, flexural, and impact properties of water immersed specimens were conducted and compared with dry specimens as per the ASTM standard. It is concluded that the water uptake of basalt fibre is considerable loss in the mechanical properties of the composites.

  15. The Silica-Water Interface: How the Silanols Determine the Surface Acidity and Modulate the Water Properties.

    Science.gov (United States)

    Sulpizi, Marialore; Gaigeot, Marie-Pierre; Sprik, Michiel

    2012-03-13

    Silica is the most abundant metal oxide and the main component of the Earth's crust. Its behavior in contact with water plays a critical role in a variety of geochemical and environmental processes. Despite its key role, the details of the aqueous silica interface at the microscopic molecular level are still elusive. Here we provide such a detailed understanding of the molecular behavior of the silica-water interface, using density functional theory based molecular dynamics (DFTMD) simulations, where a consistent treatment of the electronic structure of solvent and surface is provided. We have calculated the acidity of the silanol groups at the interface directly from the DFTMD simulations, without any fitting of parameters to the experimental data. We find two types of silanol groups at the surface of quartz: out-of-plane silanols with a strong acidic character (pKa = 5.6), which consequently results in the formation of strong and short hydrogen bonds with water molecules at the interface, and in-plane silanols with a pKa of 8.5, forming weak hydrogen bonds with the interfacial water molecules. Our estimate of the quartz point of zero charge (1.0) is found in good agreement with the experimental value of 1.9. We have also shown how the silanols orientation and their hydrogen bond properties are responsible for an amphoteric behavior of the surface. A detailed analysis has identified two species of adsorbed water molecules at the solid-liquid interface, which using the language of vibrational spectroscopy can be identified as "liquid-like" and "ice-like" water or, in other words, water molecules forming respectively weak and strong H-bonds with the oxide surface. These two populations of water are in turn responsible for two distinct peaks in the infrared spectrum of interfacial water and thus provide a molecular explanation of the experimental sum frequency generation spectrum recorded in the literature. In the specific case of quartz, we show that the liquid

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

    Science.gov (United States)

    Huang, Junrong; Chen, Zhenghong; Xu, Yalun; Li, Hongliang; Liu, Shuxing; Yang, Daqing; Schols, Henk A

    2014-02-15

    To 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, original and remaining granules of waxy potato starch had similar rapid visco analyzer (RVA) pasting profiles, while those of two normal potato starches behaved obviously different from each other. All remaining granules had lower peak viscosity than the corresponding original granules. Contribution of waxy potato starch granule's inner portion to the peak viscosity was significant more than those of normal potato starches. The shell structure appearing on the remaining granule surface for waxy potato starch was smoother and thinner than that for normal potato starches as observed by scanning electron microscopy, indicating a more regular structure of shell and a more ordered packing of shell for waxy potato starch granules. The blocklet size of waxy potato starch was smaller and more uniform than those of normal potato starches as shown by atomic force microscopy images of original and remaining granules. In general, our results provided the evidence for the spatial structure diversity between waxy and normal potato starch granules: outer layer and inner portion of waxy potato starch granule had similar structure, while outer layer had notably different structure from inner portion for normal potato starch granule.