WorldWideScience

Sample records for surface adhesive energy

  1. Surface energy and viscoelasticity influence caramel adhesiveness.

    Science.gov (United States)

    Wagoner, Ty B; Foegeding, Edward Allen

    2017-08-26

    Adhesion is an important textural attribute that directs consumer eating patterns and behaviors and can be a negative attribute during food processing. The objectives of this study were to modify caramel formulation and compare adhesion to different materials to quantify the influence of surface energetics and viscoelasticity on caramel adhesiveness. Mechanical adhesion was viewed in the context of pressure sensitive tack theory, where adhesion is controlled by viscoelasticity of the adhesive material and the surface energy relationship of material and probe. Caramel samples varied in total amount of fat and protein, and mechanical adhesion was measured using a series of materials with total surface energies of 39.7-53.2 mJ/m 2 . Adhesiveness decreased as fat and protein content increased, with a significant effect of total surface energy. Viscoelasticity was modeled using creep recovery data fit to a four-element Burger mechanistic model. Burger model parameters representing retarded elasticity correlated strongly with adhesiveness. The results suggest two zones of adhesion based on formulation, one driven by both surface energy relationships-most notably dispersive and total surface energy-and viscoelasticity, and the other driven solely by viscoelasticity. Relationships between mechanical properties and adhesion have been explored but are still not well understood, and could aid in the design of food products with a controlled level of adhesion. The results of this study indicate the importance of considering material surface energy when measuring mechanical adhesion or texture profile analysis. Understanding the relationships between viscoelastic behavior and adhesion can be used to make inferences on perceived texture. © 2017 Wiley Periodicals, Inc.

  2. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    Abstract. We calculated the adhesion energy, the surface traction and the surface energy of liquid xenon using molecular dynamics (MD) simulation. The value of the adhesion energy for liquid xenon at a reduced density of 0.630 was found to be 0.591 J/m2 and the surface traction has a peak at z = 3.32 Å. It was observed ...

  3. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    We calculated the adhesion energy, the surface traction and the surface energy of liquid xenon using molecular dynamics (MD) simulation. The value of the adhesion energy for liquid xenon at a reduced density of 0.630 was found to be 0.591 J/m2 and the surface traction has a peak at = 3.32 Å. It was observed that the ...

  4. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... Home; Journals; Pramana – Journal of Physics; Volume 77; Issue 6. Adhesion energy, surface ... 2 G A Adebayo1. Department of Physics, University of Agriculture, Abeokuta, Nigeria; Department of Pure and Applied Physics, College of Pure and Applied Science, Caleb University, Imota, Lagos, Nigeria ...

  5. Relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives.

    Science.gov (United States)

    Nagura, Yuko; Tsujimoto, Akimasa; Barkmeier, Wayne W; Watanabe, Hidehiko; Johnson, William W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2018-04-01

    The relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives was investigated. The initial shear bond strengths and shear fatigue strengths of five universal adhesives to enamel were determined with and without phosphoric acid pre-etching. The surface free-energy characteristics of adhesive-treated enamel with and without pre-etching were also determined. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were higher than those to ground enamel. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were material dependent, unlike those to ground enamel. The surface free-energy of the solid (γ S ) and the hydrogen-bonding force (γSh) of universal adhesive-treated enamel were different depending on the adhesive, regardless of the presence or absence of pre-etching. The bond fatigue durability of universal adhesives was higher to pre-etched enamel than to ground enamel. In addition, the bond fatigue durability to pre-etched enamel was material dependent, unlike that to ground enamel. The surface free-energy characteristics of universal adhesive-treated enamel were influenced by the adhesive type, regardless of the presence or absence of pre-etching. The surface free-energy characteristics of universal adhesive-treated enamel were related to the results of the bond fatigue durability. © 2018 Eur J Oral Sci.

  6. Nanometer polymer surface features: the influence on surface energy, protein adsorption and endothelial cell adhesion

    Science.gov (United States)

    Carpenter, Joseph; Khang, Dongwoo; Webster, Thomas J.

    2008-12-01

    Current small diameter (lactic-co-glycolic acid) (PLGA) surfaces elevated endothelial cell adhesion, proliferation, and extracellular matrix synthesis when compared to nanosmooth surfaces. Nonetheless, these studies failed to address the importance of lateral and vertical surface feature dimensionality coupled with surface free energy; nor did such studies elicit an optimum specific surface feature size for promoting endothelial cell adhesion. In this study, a series of highly ordered nanometer to submicron structured PLGA surfaces of identical chemistry were created using a technique employing polystyrene nanobeads and poly(dimethylsiloxane) (PDMS) molds. Results demonstrated increased endothelial cell adhesion on PLGA surfaces with vertical surface features of size less than 18.87 nm but greater than 0 nm due to increased surface energy and subsequently protein (fibronectin and collagen type IV) adsorption. Furthermore, this study provided evidence that the vertical dimension of nanometer surface features, rather than the lateral dimension, is largely responsible for these increases. In this manner, this study provides key design parameters that may promote vascular graft efficacy.

  7. Adhesion Evaluation of Asphalt-Aggregate Interface Using Surface Free Energy Method

    Directory of Open Access Journals (Sweden)

    Jie Ji

    2017-02-01

    Full Text Available The influence of organic additives (Sasobit and RH and water on the adhesion of the asphalt-aggregate interface was studied according to the surface free energy theory. Two asphalt binders (SK-70 and SK-90, and two aggregate types (limestone and basalt were used in this study. The sessile drop method was employed to test surface free energy components of asphalt, organic additives and aggregates. The adhesion models of the asphalt-aggregate interface in dry and wet conditions were established, and the adhesion work was calculated subsequently. The energy ratios were built to evaluate the effect of organic additives and water on the adhesiveness of the asphalt-aggregate interface. The results indicate that the addition of organic additives can enhance the adhesion of the asphalt-aggregate interface in dry conditions, because organic additives reduced the surface free energy of asphalt. However, the organic additives have hydrophobic characteristics and are sensitive to water. As a result, the adhesiveness of the asphalt-aggregate interface of the asphalt containing organic additives in wet conditions sharply decreased due to water damage to asphalt and organic additives. Furthermore, the compatibility of asphalt, aggregate with organic additive was noted and discussed.

  8. Measurement of adhesion properties between topcoat paint and metallized/galvanized steel with surface energy measurement equipment.

    Science.gov (United States)

    2013-09-01

    The objectives of this research project are: (1) Compare the adhesion properties of NEPCOAT-approved topcoat paint over : metallized or galvanized steel. Use surface-energy measuring technique to characterize the wetting properties of the liqui...

  9. Influence of an oxygen-inhibited layer on enamel bonding of dental adhesive systems: surface free-energy perspectives.

    Science.gov (United States)

    Ueta, Hirofumi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Oouchi, Hajime; Sai, Keiichi; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The influence of an oxygen-inhibited layer (OIL) on the shear bond strength (SBS) to enamel and surface free-energy (SFE) of adhesive systems was investigated. The adhesive systems tested were Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to bovine enamel surfaces to determine the SBS, with and without an OIL, of adhesives. The SFE of cured adhesives with and without an OIL were determined by measuring the contact angles of three test liquids. There were no significant differences in the mean SBS of SM and CS specimens with or without an OIL; however, the mean SBS of SU specimens with an OIL was significantly higher than that of SU specimens without an OIL. For all three systems, the mean total SFE (γS), polarity force (γSp), and hydrogen bonding force (γSh) values of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The results of this study indicate that the presence of an OIL promotes higher SBS of a single-step self-etch adhesive system, but not of a three-step or a two-step self-etch primer system. The SFE values of cured adhesives with an OIL were significantly higher than those without an OIL. The SFE characteristics of the OIL of adhesives differed depending on the type of adhesive. © 2015 Eur J Oral Sci.

  10. Influence of surface-energy components of Ni-P-TiO2-PTFE nanocomposite coatings on bacterial adhesion.

    Science.gov (United States)

    Liu, Chen; Zhao, Qi

    2011-08-02

    The influence of total surface energy on bacterial adhesion has been investigated intensively with the frequent conclusion that bacterial adhesion is less on low-energy surfaces. However, there are also a number of contrary findings that high-energy surfaces have a smaller biofouling tendency. Recently, it was found that the CQ ratio, which is defined as the ratio of Lifshitz-van der Waals (LW) apolar to electron donor surface-energy components of substrates, has a strong correlation to bacterial adhesion. However, the electron donor surface-energy components of substrates varied over only a very limited range. In this article, a series of Ni-P-TiO(2)-PTFE nanocomposite coatings with wide range of surface-energy components were prepared using an electroless plating technique. The bacterial adhesion and removal on the coatings were evaluated with different bacteria under both static and flow conditions. The experimental results demonstrated that there was a strong correlation between bacterial attachment (or removal) and the CQ ratio. The coatings with the lowest CQ ratio had the lowest bacterial adhesion or the highest bacterial removal, which was explained using the extented DLVO theory.

  11. Adhesive-Bonded Composite Joint Analysis with Delaminated Surface Ply Using Strain-Energy Release Rate

    Science.gov (United States)

    Chadegani, Alireza; Yang, Chihdar; Smeltzer, Stanley S. III

    2012-01-01

    This paper presents an analytical model to determine the strain energy release rate due to an interlaminar crack of the surface ply in adhesively bonded composite joints subjected to axial tension. Single-lap shear-joint standard test specimen geometry with thick bondline is followed for model development. The field equations are formulated by using the first-order shear-deformation theory in laminated plates together with kinematics relations and force equilibrium conditions. The stress distributions for the adherends and adhesive are determined after the appropriate boundary and loading conditions are applied and the equations for the field displacements are solved. The system of second-order differential equations is solved to using the symbolic computation tool Maple 9.52 to provide displacements fields. The equivalent forces at the tip of the prescribed interlaminar crack are obtained based on interlaminar stress distributions. The strain energy release rate of the crack is then determined by using the crack closure method. Finite element analyses using the J integral as well as the crack closure method are performed to verify the developed analytical model. It has been shown that the results using the analytical method correlate well with the results from the finite element analyses. An attempt is made to predict the failure loads of the joints based on limited test data from the literature. The effectiveness of the inclusion of bondline thickness is justified when compared with the results obtained from the previous model in which a thin bondline and uniform adhesive stresses through the bondline thickness are assumed.

  12. Influence of the Oxygen-inhibited Layer on Bonding Performance of Dental Adhesive Systems: Surface Free Energy Perspectives.

    Science.gov (United States)

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-01-01

    To examine the influence of the oxygen inhibited layer (OIL) on shear bond strength (SBS) to dentin and surface free energy (SFE) characteristics of different adhesive systems. Three adhesive systems were used: Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to dentin surfaces to determine SBS with and without OIL of adhesives. The SFE, dispersion force (γSd), polarity force (γSp), and hydrogen bonding force (γSh) of cured adhesives with and without an OIL were measured. Two-way ANOVA and Tukey's honestly significant difference (HSD) test were used for analysis of SBS data, and one-way ANOVA and Tukey's HSD test were used for the SFE and contact angle data. The SBS of SM and CS showed no significant differences between specimens with and without the OIL. However, the SBS of SU with the OIL was significantly higher than without the OIL. The SFE, γSp, and γSh of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The SFE, γSp, and γSh of SM and CS with an OIL were significantly higher than those of SU with an OIL. The results of this study indicate that the presence of an OIL with a single-step self-etching adhesive promotes higher SBS to dentin, unlike in the other types of adhesive systems. The SFE characteristics of the OIL of dental adhesives differed depending on the type of adhesive system.

  13. Influence of application method on surface free-energy and bond strength of universal adhesive systems to enamel.

    Science.gov (United States)

    Imai, Arisa; Takamizawa, Toshiki; Sai, Keiichi; Tsujimoto, Akimasa; Nojiri, Kie; Endo, Hajime; Barkmeier, Wayne W; Latta, Mark A; Miyazaki, Masashi

    2017-10-01

    The aim of the present study was to determine the influence of different adhesive application methods and etching modes on enamel bond effectiveness of universal adhesives using shear bond strength (SBS) testing and surface free-energy (SFE) measurements. The adhesives Scotchbond Universal, All-Bond Universal, Adhese Universal, and G-Premio Bond were used. Prepared bovine enamel specimens were divided into four groups, based on type of adhesive, and subjected to the following surface treatments: (i) total-etch mode with active application; (ii) total-etch mode with inactive application; (iii) self-etch mode with active application; and (iv) self-etch mode with inactive application. Bonded specimens were subjected to SBS testing. The SFE of the enamel surfaces with adhesive was measured after rinsing with acetone and water. The SBS values in total-etch mode were significantly higher than those in self-etch mode. In total-etch mode, significantly lower SBS values were observed with active application compared with inactive application; in contrast, in self-etch mode there were no significant differences in SBS between active and inactive applications. A reduction in total SFE was observed for active application compared with inactive application. The interaction between etching mode and application method was statistically significant, and the application method significantly affected enamel bond strength in total-etch mode. © 2017 Eur J Oral Sci.

  14. Influence of light intensity on surface-free energy and dentin bond strength of single-step self-etch adhesives.

    Science.gov (United States)

    Nojiri, Kie; Tsujimoto, Akimasa; Suzuki, Takayuki; Shibasaki, Syo; Matsuyoshi, Saki; Takamizawa, Toshiki; Miyazaki, Masashi

    2015-01-01

    In this study, we investigated the influence of light intensity on the surface-free energy and dentin bond strength of single-step selfetch adhesives. The adhesives were applied to the dentin surfaces of bovine mandibular incisors and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm(2). Surface-free energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. Dentin bond strengths of the specimens were also measured. Polymerization with a higher light intensity resulted in a lower surface-free energy of the cured adhesives. The greatest bond strength was achieved when a light intensity of 400 mW/cm(2) or greater was used. Our data suggest that the surface-free energy and dentin bond strength of single-step self-etch adhesives are affected by light intensity of the curing unit.

  15. Influence of warm air-drying on enamel bond strength and surface free-energy of self-etch adhesives.

    Science.gov (United States)

    Shiratsuchi, Koji; Tsujimoto, Akimasa; Takamizawa, Toshiki; Furuichi, Tetsuya; Tsubota, Keishi; Kurokawa, Hiroyasu; Miyazaki, Masashi

    2013-08-01

    We examined the effect of warm air-drying on the enamel bond strengths and the surface free-energy of three single-step self-etch adhesives. Bovine mandibular incisors were mounted in self-curing resin and then wet ground with #600 silicon carbide (SiC) paper. The adhesives were applied according to the instructions of the respective manufacturers and then dried in a stream of normal (23°C) or warm (37°C) air for 5, 10, and 20 s. After visible-light irradiation of the adhesives, resin composites were condensed into a mold and polymerized. Ten samples per test group were stored in distilled water at 37°C for 24 h and then the bond strengths were measured. The surface free-energies were determined by measuring the contact angles of three test liquids placed on the cured adhesives. The enamel bond strengths varied according to the air-drying time and ranged from 15.8 to 19.1 MPa. The trends for the bond strengths were different among the materials. The value of the γS⁺ component increased slightly when drying was performed with a stream of warm air, whereas that of the γS⁻ component decreased significantly. These data suggest that warm air-drying is essential to obtain adequate enamel bond strengths, although increasing the drying time did not significantly influence the bond strength. © 2013 Eur J Oral Sci.

  16. Cooptimization of Adhesion and Power Conversion Efficiency of Organic Solar Cells by Controlling Surface Energy of Buffer Layers.

    Science.gov (United States)

    Lee, Inhwa; Noh, Jonghyeon; Lee, Jung-Yong; Kim, Taek-Soo

    2017-10-25

    Here, we demonstrate the cooptimization of the interfacial fracture energy and power conversion efficiency (PCE) of poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT)-based organic solar cells (OSCs) by surface treatments of the buffer layer. The investigated surface treatments of the buffer layer simultaneously changed the crack path and interfacial fracture energy of OSCs under mechanical stress and the work function of the buffer layer. To investigate the effects of surface treatments, the work of adhesion values were calculated and matched with the experimental results based on the Owens-Wendt model. Subsequently, we fabricated OSCs on surface-treated buffer layers. In particular, ZnO layers treated with poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) simultaneously satisfied the high mechanical reliability and PCE of OSCs by achieving high work of adhesion and optimized work function.

  17. Effect of cleaning and storage on quartz substrate adhesion and surface energy

    Science.gov (United States)

    Balachandran, Dave; John, Arun

    2014-04-01

    The force of adhesion of 50 nm diameter diamond-like carbon sphere probes to three quartz substrates was measured using an atomic force microscope. The force of adhesion was measured prior to cleaning, within 10 minutes after cleaning, after storage in an N2-purged cabinet, and after storage in an N2-purged vacuum oven. The evaluated cleaning recipes were SC1-like, SPM-like, and HF-based, each followed by ultra-pure deionized water (UPW) rinse and spin drying. The measurements were conducted in a Class 100 clean room at approximately 50% relative humidity. In addition, contact angle measurements were made on three additional quartz substrates using UPW before cleaning, after cleaning, and throughout N2 storage. The adhesion force increased after cleaning as compared to the pre-cleaned state, continued to increase until reaching a maximum after 5 days of N2 storage, and then decreased after 26 days for all three substrates. One substrate was then stored in a vacuum oven for 3 days, and the adhesion force decreased to 46% of the pre-cleaned state. The contact angle was reduced from over 30° before cleaning to 0° immediately after cleaning. During subsequent N2 storage, the contact angle increased to 5° or greater after 18 hours for the substrate cleaned with the HF-based recipe and after 15 days for the substrates cleaned by the SC1-like and SPM-like recipes.

  18. Influence of duration of phosphoric acid pre-etching on bond durability of universal adhesives and surface free-energy characteristics of enamel.

    Science.gov (United States)

    Tsujimoto, Akimasa; Barkmeier, Wayne W; Takamizawa, Toshiki; Watanabe, Hidehiko; Johnson, William W; Latta, Mark A; Miyazaki, Masashi

    2016-08-01

    The purpose of this study was to evaluate the influence of duration of phosphoric acid pre-etching on the bond durability of universal adhesives and the surface free-energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no-pre-etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre-etching groups were prepared: enamel pre-etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free-energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre-etched showed significantly higher SBS and surface free-energy values than the specimens that had not been pre-etched, regardless of the aging condition and adhesive type. The SBS and surface free-energy values did not increase for pre-etching times of longer than 3 s. There were no significant differences in SBS values and surface free-energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre-etching of enamel improves the bond durability of universal adhesives and the surface free-energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre-etching times of longer than 3 s. © 2016 Eur J Oral Sci.

  19. Influence of Curing Mode on the Surface Energy and Sorption/Solubility of Dental Self-Adhesive Resin Cements

    Directory of Open Access Journals (Sweden)

    Hyun-Jin Kim

    2017-02-01

    Full Text Available This study investigated the influence of curing mode (dual- or self-cure on the surface energy and sorption/solubility of four self-adhesive resin cements (SARCs and one conventional resin cement. The degree of conversion (DC and surface energy parameters including degree of hydrophilicity (DH were determined using Fourier transform infrared spectroscopy and contact angle measurements, respectively (n = 5. Sorption and solubility were assessed by mass gain or loss after storage in distilled water or lactic acid for 60 days (n = 5. A linear regression model was used to correlate between the results (%DC vs. DH and %DC/DH vs. sorption/solubility. For all materials, the dual-curing consistently produced significantly higher %DC values than the self-curing (p < 0.05. Significant negative linear regressions were established between the %DC and DH in both curing modes (p < 0.05. Overall, the SARCs showed higher sorption/solubility values, in particular when immersed in lactic acid, than the conventional resin cement. Linear regression revealed that %DC and DH were negatively and positively correlated with the sorption/solubility values, respectively. Dual-curing of SARCs seems to lower the sorption and/or solubility in comparison with self-curing by increased %DC and occasionally decreased hydrophilicity.

  20. The Effect of Phosphoric Acid Pre-etching Times on Bonding Performance and Surface Free Energy with Single-step Self-etch Adhesives.

    Science.gov (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miyazaki, M

    2016-01-01

    The purpose of this study was to evaluate the effect of phosphoric acid pre-etching times on shear bond strength (SBS) and surface free energy (SFE) with single-step self-etch adhesives. The three single-step self-etch adhesives used were: 1) Scotchbond Universal Adhesive (3M ESPE), 2) Clearfil tri-S Bond (Kuraray Noritake Dental), and 3) G-Bond Plus (GC). Two no pre-etching groups, 1) untreated enamel and 2) enamel surfaces after ultrasonic cleaning with distilled water for 30 seconds to remove the smear layer, were prepared. There were four pre-etching groups: 1) enamel surfaces were pre-etched with phosphoric acid (Etchant, 3M ESPE) for 3 seconds, 2) enamel surfaces were pre-etched for 5 seconds, 3) enamel surfaces were pre-etched for 10 seconds, and 4) enamel surfaces were pre-etched for 15 seconds. Resin composite was bonded to the treated enamel surface to determine SBS. The SFEs of treated enamel surfaces were determined by measuring the contact angles of three test liquids. Scanning electron microscopy was used to examine the enamel surfaces and enamel-adhesive interface. The specimens with phosphoric acid pre-etching showed significantly higher SBS and SFEs than the specimens without phosphoric acid pre-etching regardless of the adhesive system used. SBS and SFEs did not increase for phosphoric acid pre-etching times over 3 seconds. There were no significant differences in SBS and SFEs between the specimens with and without a smear layer. The data suggest that phosphoric acid pre-etching of ground enamel improves the bonding performance of single-step self-etch adhesives, but these bonding properties do not increase for phosphoric acid pre-etching times over 3 seconds.

  1. Characterization of neutrophil adhesion to different titanium surfaces

    Indian Academy of Sciences (India)

    Topographic roughness was demonstrated as higher for SLA treated surfaces, measured by atomic force microscopy and elemental analysis was performed by energy dispersive X-ray, showing a similar composition for both surfaces. The adhesion of neutrophils to the `rough' Ti surface was initially stronger than adhesion ...

  2. Tailoring of the PS surface with low energy ions: Relevance to growth and adhesion of noble metals

    International Nuclear Information System (INIS)

    Zaporojtchenko, V.; Zekonyte, J.; Wille, S.; Schuermann, U.; Faupel, F.

    2005-01-01

    Ion-polymer interaction induces different phenomena in the near surface layer of polymers, and promotes its adhesion to metals. Using XPS, TEM and AFM, polystyrene surface was examined after 1 keV ion-beam treatments with oxygen, nitrogen and argon ions in the ion fluence range from 10 12 to 10 16 cm -2 to clarify the following points: chemical reaction after treatment in vacuum and after exposure to air, identification of adsorption-relevant species for metal atoms, formation of cross-links in the outermost polymer layer. The early stages of metal-polymer interface formation during metallization play a crucial role in the metal-polymer adhesion. Therefore, the influence of the ion fluence and ion chemistry on the condensation of noble metals, film growth and peel strength were measured. The peel strength showed a maximum at a certain fluence depending on ion chemistry. For example, the surface treatment with very low fluence of oxygen ions improved the adhesion between copper and polystyrene by two orders of magnitude without significantly increasing the surface roughness measured with AFM. The locus of failure changed at the same time from interfacial failure for untreated polymer surfaces to cohesive failure in the polymer for modified surfaces. A multilayer model of the metal-polymer interface after ion treatment is suggested

  3. Gecko adhesion pad: a smart surface?

    Science.gov (United States)

    Pesika, Noshir S.; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  4. Gecko adhesion pad: a smart surface?

    Energy Technology Data Exchange (ETDEWEB)

    Pesika, Noshir S [Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118 (United States); Zeng Hongbo [Chemical and Materials Engineering Department, University of Alberta, Edmonton, AB, T6G 2V4 (Canada); Kristiansen, Kai; Israelachvili, Jacob [Chemical Engineering Department, University of California, Santa Barbara, CA 93117 (United States); Zhao, Boxin [Chemical Engineering Department and Waterloo Institute of Nanotechnology, University of Waterloo, Ontario, N2L 3G1 (Canada); Tian Yu [State Key Laboratory of Tribology, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China); Autumn, Kellar, E-mail: npesika@tulane.ed [Department of Biology, Lewis and Clark College, Portland, OR 97219 (United States)

    2009-11-18

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  5. Gecko adhesion pad: a smart surface?

    International Nuclear Information System (INIS)

    Pesika, Noshir S; Zeng Hongbo; Kristiansen, Kai; Israelachvili, Jacob; Zhao, Boxin; Tian Yu; Autumn, Kellar

    2009-01-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  6. Stretchable, Adhesion-Tunable Dry Adhesive by Surface Wrinkling

    KAUST Repository

    Jeong, Hoon Eui

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (∼10.8 N/cm2) and shear adhesion (∼14.7 N/cm2) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of∼3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of ∼0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment. © 2010 American Chemical Society.

  7. Wet adhesion and adhesive locomotion of snails on anti-adhesive non-wetting surfaces.

    Directory of Open Access Journals (Sweden)

    Neil J Shirtcliffe

    Full Text Available Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted, texture (smooth, rough or granular or wetting property (hydrophilic or hydrophobic via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces.

  8. Wet adhesion and adhesive locomotion of snails on anti-adhesive non-wetting surfaces.

    Science.gov (United States)

    Shirtcliffe, Neil J; McHale, Glen; Newton, Michael I

    2012-01-01

    Creating surfaces capable of resisting liquid-mediated adhesion is extremely difficult due to the strong capillary forces that exist between surfaces. Land snails use this to adhere to and traverse across almost any type of solid surface of any orientation (horizontal, vertical or inverted), texture (smooth, rough or granular) or wetting property (hydrophilic or hydrophobic) via a layer of mucus. However, the wetting properties that enable snails to generate strong temporary attachment and the effectiveness of this adhesive locomotion on modern super-slippy superhydrophobic surfaces are unclear. Here we report that snail adhesion overcomes a wide range of these microscale and nanoscale topographically structured non-stick surfaces. For the one surface which we found to be snail resistant, we show that the effect is correlated with the wetting response of the surface to a weak surfactant. Our results elucidate some critical wetting factors for the design of anti-adhesive and bio-adhesion resistant surfaces.

  9. Adhesion force between cyclopentane hydrate and mineral surfaces.

    Science.gov (United States)

    Aman, Zachary M; Leith, William J; Grasso, Giovanny A; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2013-12-17

    Clathrate hydrate adhesion forces play a critical role in describing aggregation and deposition behavior in conventional energy production and transportation. This manuscript uses a unique micromechanical force apparatus to measure the adhesion force between cyclopentane hydrate and heterogeneous quartz and calcite substrates. The latter substrates represent models for coproduced sand and scale often present during conventional energy production and transportation. Micromechanical adhesion force data indicate that clathrate hydrate adhesive forces are 5-10× larger for calcite and quartz minerals than stainless steel. Adhesive forces further increased by 3-15× when increasing surface contact time from 10 to 30 s. In some cases, liquid water from within the hydrate shell contacted the mineral surface and rapidly converted to clathrate hydrate. Further measurements on mineral surfaces with physical control of surface roughness showed a nonlinear dependence of water wetting angle on surface roughness. Existing adhesive force theory correctly predicted the dependence of clathrate hydrate adhesive force on calcite wettability, but did not accurately capture the dependence on quartz wettability. This comparison suggests that the substrate surface may not be inert, and may contribute positively to the strength of the capillary bridge formed between hydrate particles and solid surfaces.

  10. Adhesion control between resist patterns and photomask blank surfaces

    Science.gov (United States)

    Kurihara, Masaaki; Hatakeyama, Sho; Yoshida, Kouji; Nagai, Takaharu; Totsukawa, Daisuke; Fukuda, Masaharu; Morikawa, Yasutaka; Mohri, Hiroshi; Hoga, Morihisa; Hayashi, Naoya; Ohtani, Hiroyuki; Fujihira, Masamichi

    2009-04-01

    Most problems in photomask fabrication such as pattern collapse, haze, and cleaning damage are related to the behavior of surfaces and interfaces of resists, opaque layers, and quartz substrates. Therefore, it is important to control the corresponding surface and interface energies in photomask fabrication processes. In particular, adhesion analysis in microscopic regions is strongly desirable to optimize material and process designs in photomask fabrication. We applied the direct peeling (DP) method with a scanning probe microscope (SPM) tip and measured the adhesion of resist patterns on Cr and quartz surfaces for photomask process optimization. We measured adhesion and frictional forces between the resulting collapsed resist pillar and the Cr or the quartz surface before and after the sliding. We also studied the effect of surface property of the Cr and quartz surfaces to resist adhesion. The adhesion could be controlled by surface modification using silanes and surface roughness on Cr blanks. We also discuss the relationship between the adhesion observed with the DP method and the properties of the modified surfaces including water contact angles and local adhesive forces measured from force-distance curves with an SPM.

  11. The effect of surface roughness and viscoelasticity on rubber adhesion.

    Science.gov (United States)

    Tiwari, A; Dorogin, L; Bennett, A I; Schulze, K D; Sawyer, W G; Tahir, M; Heinrich, G; Persson, B N J

    2017-05-21

    Adhesion between silica glass or acrylic balls and silicone elastomers and various industrial rubbers is investigated. The work of adhesion during pull-off is found to strongly vary depending on the system, which we attribute to the two opposite effects: (1) viscoelastic energy dissipation close to an opening crack tip and (2) surface roughness. Introducing surface roughness on the glass ball is found to increase the work of adhesion for soft elastomers, while for the stiffer elastomers it results in a strong reduction in the work of adhesion. For the soft silicone elastomers a strong increase in the work of adhesion with increasing pull-off velocity is observed, which may result from the non-adiabatic processes associated with molecular chain pull-out. In general, the work of adhesion is decreased after repeated contacts due to the transfer of molecules from the elastomers to the glass ball. Thus, extracting the free chains (oligomers) from the silicone elastomers is shown to make the work of adhesion independent of the number of contacts. The viscoelastic properties (linear and nonlinear) of all of the rubber compounds are measured, and the velocity dependent crack opening propagation energy at the interface is calculated. Silicone elastomers show a good agreement between the measured work of adhesion and the predicted results, but carbon black filled hydrogenated nitrile butadiene rubber compounds reveal that strain softening at the crack tip may play an important role in determining the work of adhesion. Additionally, adhesion measurement under submerged conditions in distilled water and water + soap solutions are also performed: a strong reduction in the work of adhesion is measured for the silicone elastomers submerged in water, and a complete elimination of adhesion is found for the water + soap solution attributed to an osmotic repulsion between the negatively charged surface of the glass and the elastomer.

  12. Tooth surface treatment strategies for adhesive cementation

    OpenAIRE

    Rohr, Nadja; Fischer, Jens

    2017-01-01

    PURPOSE The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one sel...

  13. Cell adhesion and growth on ion-implanted polymer surface

    International Nuclear Information System (INIS)

    Lee, Jae-Suk; Kaibara, M.; Iwaki, M.; Sasabe, H.; Suzuki, Y.; Kusakabe, M.

    1992-01-01

    The adhesion and growth of endothelial cells on ion-implanted polystyrene and segmented polyurethane surface were investigated. Ions of Na + , N 2 + , O 2 + , Ar + and Kr + were implanted to the polymer surface with ion fluences between 1 x 10 15 and 3 x 10 17 ions/cm 2 at energy of 150 KeV at room temperature. Ion-implanted polymers were characterized by FT-IR-ATR an Raman spectroscopies. The adhesion and proliferation of bovine aorta endothelial cells on ion-implanted polymer surface were observed by an optical microscope. The rate of growth of BAECs on ion-implanted PSt was faster than that on non-implanted PSt. Complete cell adhesion and growth were observed on ion-implanted SPU, whereas the adhesion and growth of BAECs on the non-implanted SPU was not observed. It was attempted to control the cell culture on the ion-implanted domain fabricated using a mask. (author)

  14. Enhanced adhesion of bioinspired nanopatterned elastomers via colloidal surface assembly

    Science.gov (United States)

    Akerboom, Sabine; Appel, Jeroen; Labonte, David; Federle, Walter; Sprakel, Joris; Kamperman, Marleen

    2015-01-01

    We describe a scalable method to fabricate nanopatterned bioinspired dry adhesives using colloidal lithography. Close-packed monolayers of polystyrene particles were formed at the air/water interface, on which polydimethylsiloxane (PDMS) was applied. The order of the colloidal monolayer and the immersion depth of the particles were tuned by altering the pH and ionic strength of the water. Initially, PDMS completely wetted the air/water interface outside the monolayer, thereby compressing the monolayer as in a Langmuir trough; further application of PDMS subsequently covered the colloidal monolayers. PDMS curing and particle extraction resulted in elastomers patterned with nanodimples. Adhesion and friction of these nanopatterned surfaces with varying dimple depth were studied using a spherical probe as a counter-surface. Compared with smooth surfaces, adhesion of nanopatterned surfaces was enhanced, which is attributed to an energy-dissipating mechanism during pull-off. All nanopatterned surfaces showed a significant decrease in friction compared with smooth surfaces. PMID:25392404

  15. Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

    International Nuclear Information System (INIS)

    Coulon, J.F.; Tournerie, N.; Maillard, H.

    2013-01-01

    Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m 2 to 70 mJ/m 2 because the plasma pretreatment led to the formation of hydrophilic C-O and C=O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

  16. Surface tension and deformation in soft adhesion

    Science.gov (United States)

    Jensen, Katharine

    Modern contact mechanics was originally developed to account for the competition between adhesion and elasticity for relatively stiff deformable materials like rubber, but much softer sticky materials are ubiquitous in biology, engineering, and everyday consumer products. In such soft materials, the solid surface tension can also play an important role in resisting shape change, and significantly modify the physics of contact with soft matter. We report indentation and pull-off experiments that bring small, rigid spheres into adhesive contact with compliant silicone gel substrates, varying both the surface functionalization of the spheres and the bulk elastic properties of the gels. We map the resulting deformation profiles using optical microscopy and image analysis. We examine the substrate geometry in light of capillary and elastic theories in order to explore the interplay of surface tension and bulk elasticity in governing soft adhesion.

  17. Surface Modifications in Adhesion and Wetting

    Science.gov (United States)

    Longley, Jonathan

    Advances in surface modification are changing the world. Changing surface properties of bulk materials with nanometer scale coatings enables inventions ranging from the familiar non-stick frying pan to advanced composite aircraft. Nanometer or monolayer coatings used to modify a surface affect the macro-scale properties of a system; for example, composite adhesive joints between the fuselage and internal frame of Boeing's 787 Dreamliner play a vital role in the structural stability of the aircraft. This dissertation focuses on a collection of surface modification techniques that are used in the areas of adhesion and wetting. Adhesive joints are rapidly replacing the familiar bolt and rivet assemblies used by the aerospace and automotive industries. This transition is fueled by the incorporation of composite materials into aircraft and high performance road vehicles. Adhesive joints have several advantages over the traditional rivet, including, significant weight reduction and efficient stress transfer between bonded materials. As fuel costs continue to rise, the weight reduction is accelerating this transition. Traditional surface pretreatments designed to improve the adhesion of polymeric materials to metallic surfaces are extremely toxic. Replacement adhesive technologies must be compatible with the environment without sacrificing adhesive performance. Silane-coupling agents have emerged as ideal surface modifications for improving composite joint strength. As these coatings are generally applied as very thin layers (compression of a water drop between two gradient surfaces. This inchworm type motion is studied in detail and offers an alternative method to surface vibration for moving drops in microfluidic devices. The final surface modification considered is the application of a thin layer of rubber to a rigid surface. While this technique has many practical uses, such as easy release coatings in marine environments, it is applied herein to enable spontaneous

  18. Methods to study microbial adhesion on abiotic surfaces

    Directory of Open Access Journals (Sweden)

    Ana Meireles

    2015-09-01

    Full Text Available Microbial biofilms are a matrix of cells and exopolymeric substances attached to a wet and solid surface and are commonly associated to several problems, such as biofouling and corrosion in industries and infectious diseases in urinary catheters and prosthesis. However, these cells may have several benefits in distinct applications, such as wastewater treatment processes, microbial fuel cells for energy production and biosensors. As microbial adhesion is a key step on biofilm formation, it is very important to understand and characterize microbial adhesion to a surface. This study presents an overview of predictive and experimental methods used for the study of bacterial adhesion. Evaluation of surface physicochemical properties have a limited capacity in describing the complex adhesion process. Regarding the experimental methods, there is no standard method or platform available for the study of microbial adhesion and a wide variety of methods, such as colony forming units counting and microscopy techniques, can be applied for quantification and characterization of the adhesion process.

  19. Adhesive contact of randomly rough surfaces

    Science.gov (United States)

    Pastewka, Lars; Robbins, Mark

    2012-02-01

    The contact area, stiffness and adhesion between rigid, randomly rough surfaces and elastic substrates is studied using molecular statics and continuum simulations. The surfaces are self-affine with Hurst exponent 0.3 to 0.8 and different short λs and long λL wavelength cutoffs. The rms surface slope and the range and strength of the adhesive potential are also varied. For parameters typical of most solids, the effect of adhesion decreases as the ratio λL/λs increases. In particular, the pull-off force decreases to zero and the area of contact Ac becomes linear in the applied load L. A simple scaling argument is developed that describes the increase in the ratio Ac/L with increasing adhesion and a corresponding increase in the contact stiffness [1]. The argument also predicts a crossover to finite contact area at zero load when surfaces are exceptionally smooth or the ratio of surface tension to bulk modulus is unusually large, as for elastomers. Results that test this prediction will be presented and related to the Maugis-Dugdale [2] theories for individual asperities and the more recent scaling theory of Persson [3]. [1] Akarapu, Sharp, Robbins, Phys. Rev. Lett. 106, 204301 (2011) [2] Maugis, J. Colloid Interface Sci. 150, 243 (1992) [3] Persson, Phys. Rev. Lett. 74, 75420 (2006)

  20. Adhesion force of staphylococcus aureus on various biomaterial surfaces.

    Science.gov (United States)

    Alam, Fahad; Balani, Kantesh

    2017-01-01

    Staphylococcus comprises of more than half of all pathogens in orthopedic implant infections and they can cause major bone infection which can result in destruction of joint and bone. In the current study, adhesion force of bacteria on the surface of various biomaterial surfaces is measured using atomic force microscope (AFM). Staphylococcus aureus was immobilized on an AFM tipless cantilever as a force probe to measure the adhesion force between bacteria and biomaterials (viz. ultra-high molecular weight poly ethylene (UHMWPE), stainless steel (SS), Ti-6Al-4V alloy, hydroxyapatite (HA)). At the contact time of 10s, UHMWPE shows weak adhesion force (~4nN) whereas SS showed strong adhesion force (~15nN) due to their surface energy and surface roughness. Bacterial retention and viability experiment (3M™ petrifilm test, agar plate) dictates that hydroxyapatite shows the lowest vaibility of bacteria, whereas lowest bacterial retention is observed on UHMWPE surface. Similar results were obtained from live/dead staining test, where HA shows 65% viability, whereas on UHMWPE, SS and Ti-6Al-4V, the bacterial viability is 78%, 94% and 97%, respectively. Lower adhesion forces, constrained pull-off distance (of bacterial) and high antibacterial resistance of bioactive-HA makes it a potential biomaterial for bone-replacement arthroplasty. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Thermomechanical Mechanisms of Reducing Ice Adhesion on Superhydrophobic Surfaces.

    Science.gov (United States)

    Cohen, N; Dotan, A; Dodiuk, H; Kenig, S

    2016-09-20

    Superhydrophobic (SH) coatings have been shown to reduce freezing and ice nucleation rates, by means of low surface energy chemistry tailored with nano/micro roughness. Durability enhancement of SH surfaces is a crucial issue. Consequently, the present research on reducing ice adhesion is based on radiation-induced radical reaction for covalently bonding SiO2 nanoparticles to polymer coatings to obtain durable roughness. Results indicated that the proposed approach resulted in SH surfaces having high contact angles (>155°) and low sliding angles (reduction of shear adhesion to a variety of SH treated substrates having low thermal expansion coefficient (copper and aluminum) and high thermal expansion coefficient (polycarbonate and poly(methyl methacrylate)). It was concluded that the thermal mismatch between the adhering ice and the various substrates and its resultant interfacial thermal stresses affect the adhesion strength of the ice to the respective substrate.

  2. Tooth surface treatment strategies for adhesive cementation.

    Science.gov (United States)

    Rohr, Nadja; Fischer, Jens

    2017-04-01

    The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. The highest bond strength values for all cements were achieved with etching and primer on enamel (25.6 ± 5.3 - 32.3 ± 10.4 MPa). On dentin, etching and priming produced the highest bond strength values for all cements (8.6 ± 2.9 - 11.7 ± 3.5 MPa) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only (15.3 ± 4.1 MPa). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

  3. Surface pretreatments for medical application of adhesion

    Directory of Open Access Journals (Sweden)

    Weber Michael

    2003-09-01

    Full Text Available Abstract Medical implants and prostheses (artificial hips, tendono- and ligament plasties usually are multi-component systems that may be machined from one of three material classes: metals, plastics and ceramics. Typically, the body-sided bonding element is bone. The purpose of this contribution is to describe developments carried out to optimize the techniques , connecting prosthesis to bone, to be joined by an adhesive bone cement at their interface. Although bonding of organic polymers to inorganic or organic surfaces and to bone has a long history, there remains a serious obstacle in realizing long-term high-bonding strengths in the in vivo body environment of ever present high humidity. Therefore, different pretreatments, individually adapted to the actual combination of materials, are needed to assure long term adhesive strength and stability against hydrolysis. This pretreatment for metal alloys may be silica layering; for PE-plastics, a specific plasma activation; and for bone, amphiphilic layering systems such that the hydrophilic properties of bone become better adapted to the hydrophobic properties of the bone cement. Amphiphilic layering systems are related to those developed in dentistry for dentine bonding. Specific pretreatment can significantly increase bond strengths, particularly after long term immersion in water under conditions similar to those in the human body. The bond strength between bone and plastic for example can be increased by a factor approaching 50 (pealing work increasing from 30 N/m to 1500 N/m. This review article summarizes the multi-disciplined subject of adhesion and adhesives, considering the technology involved in the formation and mechanical performance of adhesives joints inside the human body.

  4. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    Science.gov (United States)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  5. Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jared; Bosco, Nick; Dauskardt, Reinhold

    2017-11-01

    Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.

  6. Frictional and elastic energy in gecko adhesive detachment.

    Science.gov (United States)

    Gravish, Nick; Wilkinson, Matt; Autumn, Kellar

    2008-03-06

    Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1 m s(-1). Climbing presents a significant challenge for an adhesive since it requires both strong attachment and easy, rapid removal. Conventional pressure-sensitive adhesives are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). We discovered that the energy required to detach adhering tokay gecko setae (W(d)) is modulated by the angle (theta) of a linear path of detachment. Gecko setae resist detachment when dragged towards the animal during detachment (theta = 30 degrees ) requiring W(d) = 5.0+/-0.86(s.e.) J m(-2) to detach, largely due to frictional losses. This external frictional loss is analogous to viscous internal frictional losses during detachment of pressure-sensitive adhesives. We found that, remarkably, setae possess a built-in release mechanism. Setae acted as springs when loaded in tension during attachment and returned elastic energy when detached along the optimal path (theta=130 degrees ), resulting in W(d) = -0.8+/-0.12 J m(-2). The release of elastic energy from the setal shaft probably causes spontaneous release, suggesting that curved shafts may enable easy detachment in natural, and synthetic, gecko adhesives.

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

    International Nuclear Information System (INIS)

    Huang, Pei-Hsing

    2011-01-01

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

  8. Solid Lubrication Fundamentals and Applications. Properties of Clean Surfaces: Adhesion, Friction, and Wear

    Science.gov (United States)

    Miyoshi, Kazuhisa

    1998-01-01

    This chapter presents the adhesion, friction, and wear behaviors of smooth, atomically clean surfaces of solid-solid couples, such as metal-ceramic couples, in a clean environment. Surface and bulk properties, which determine the adhesion, friction, and wear behaviors of solid-solid couples, are described. The primary emphasis is on the nature and character of the metal, especially its surface energy and ductility. Also, the mechanisms of friction and wear for clean, smooth surfaces are stated.

  9. Enhancement and suppression effects of a nanopatterned surface on bacterial adhesion

    Science.gov (United States)

    Li, Xinlei; Chen, Tongsheng

    2016-05-01

    We present a quantitative thermodynamic model to elucidate the effects of a nanopatterned surface on bacterial adhesion. Based on the established model, we studied the equilibrium state of rodlike bacterial cells adhered to a nanopillar-patterned surface. Theoretical analyses showed the physical origin of bacterial adhesion on a nanopatterned surface is actually determined by the balance between adhesion energy and deformation energy of the cell membrane. We found that there are enhancement effects on bacterial adhesion to the patterned surface with large radius and small spacing of nanopillars, but suppression effects for nanopillars with a radius smaller than a critical value. In addition, according to our model, a phase diagram has been constructed which can clarify the interrelated effects of the radius and the spacing of nanopillars. The broad agreement with experimental observations implies that these studies would provide useful guidance to the design of nanopatterned surfaces for biomedical applications.

  10. Effect of viscoelasticity on adhesion of bioinspired micropatterned epoxy surfaces.

    Science.gov (United States)

    Castellanos, Graciela; Arzt, Eduard; Kamperman, Marleen

    2011-06-21

    The effect of viscoelasticity on adhesion was investigated for micropatterned epoxy surfaces and compared to nonpatterned surfaces. A two-component epoxy system was used to produce epoxy compositions with different viscoelastic properties. Pillar arrays with flat punch tip geometries were fabricated with a two-step soft lithography process. Adhesion properties were measured with a home-built adhesion tester using a spherical sapphire probe as a counter-surface. Compared to flat controls, micropatterned epoxy samples with low viscoelasticity (i.e., low damping factors) showed at least a 20-fold reduction in pull-off force per actual contact area for both low (E' = 2.3 MPa) and high (E' = 2.3 GPa) storage moduli. This antiadhesive behavior may result from poor contact formation and indicates that the adhesion performance of commonly used elastomers for dry adhesives (e.g., polydimethylsiloxane) is governed by the interfacial viscoelasticity. Adhesion significantly increased with increasing viscoelasticity. Micropatterned samples with high viscoelasticity showed a 4-fold reduction in adhesion for aspect ratio (AR) 1.1 patterns but a 2-fold enhancement in adhesion for AR 2.2 patterns. These results indicate that viscoelasticity can enhance the effect of surface patterning on adhesion and should be considered as a significant parameter in the design of artificial patterned adhesives. © 2011 American Chemical Society

  11. Adhesive Force of a Spider Mite, Tetranychus urticae, to a Flat Smooth Surface

    Science.gov (United States)

    Mizutani, Katsumi; Egashira, Kai; Toukai, Tadashi; Ogushi, Jun

    The adhesion of a spider mite to a surface of a flat smooth plate is investigated as a model for micromachine parts to adhere to and move on such surfaces. The measurement of adhesive force is carried out under various conditions in which plate material, surface roughness of a plate and environmental humidity are differed. The adhesion mechanism is also discussed. Of the forces acting between a spider mite and a surface, one from dispersion interaction is the most dominant because (1) there is a high correlation between the adhesive force and the dispersion force component of surface energy with adhesive forces of 8.2µN for glass, 9.7µN for mica, 9.9µN for silicon and 12.1µN for gold, and because (2) high humidity and high surface roughness reduce the adhesive force. For strong adhesion based on work of adhesion, spider mites have tenent hairs with a bell-shaped end.

  12. Hydrate-phobic surfaces: fundamental studies in clathrate hydrate adhesion reduction.

    Science.gov (United States)

    Smith, J David; Meuler, Adam J; Bralower, Harrison L; Venkatesan, Rama; Subramanian, Sivakumar; Cohen, Robert E; McKinley, Gareth H; Varanasi, Kripa K

    2012-05-07

    Clathrate hydrate formation and subsequent plugging of deep-sea oil and gas pipelines represent a significant bottleneck for deep-sea oil and gas operations. Current methods for hydrate mitigation are expensive and energy intensive, comprising chemical, thermal, or flow management techniques. In this paper, we present an alternate approach of using functionalized coatings to reduce hydrate adhesion to surfaces, ideally to a low enough level that hydrodynamic shear stresses can detach deposits and prevent plug formation. Systematic and quantitative studies of hydrate adhesion on smooth substrates with varying solid surface energies reveal a linear trend between hydrate adhesion strength and the practical work of adhesion (γ(total)[1 + cos θ(rec)]) of a suitable probe liquid, that is, one with similar surface energy properties to those of the hydrate. A reduction in hydrate adhesion strength by more than a factor of four when compared to bare steel is achieved on surfaces characterized by low Lewis acid, Lewis base, and van der Waals contributions to surface free energy such that the practical work of adhesion is minimized. These fundamental studies provide a framework for the development of hydrate-phobic surfaces, and could lead to passive enhancement of flow assurance and prevention of blockages in deep-sea oil and gas operations.

  13. Scanning Surface Potential Microscopy of Spore Adhesion on Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ida [University of Tennessee, Knoxville (UTK); Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2012-01-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica.

  14. Scanning surface potential microscopy of spore adhesion on surfaces.

    Science.gov (United States)

    Lee, I; Chung, E; Kweon, H; Yiacoumi, S; Tsouris, C

    2012-04-01

    The adhesion of spores of Bacillus anthracis - the cause of anthrax and a likely biological threat - to solid surfaces is an important consideration in cleanup after an accidental or deliberate release. However, because of safety concerns, directly studying B. anthracis spores with advanced instrumentation is problematic. As a first step, we are examining the electrostatic potential of Bacillus thuringiensis (Bt), which is a closely related species that is often used as a simulant to study B. anthracis. Scanning surface potential microscopy (SSPM), also known as Kelvin probe force microscopy (KPFM), was used to investigate the influence of relative humidity (RH) on the surface electrostatic potential of Bt that had adhered to silica, mica, or gold substrates. AFM/SSPM side-by-side images were obtained separately in air, at various values of RH, after an aqueous droplet with spores was applied on each surface and allowed to dry before measurements. In the SSPM images, a negative potential on the surface of the spores was observed compared with that of the substrates. The surface potential decreased as the humidity increased. Spores were unable to adhere to a surface with an extremely negative potential, such as mica. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Micromechanical and surface adhesive properties of single saccharomyces cerevisiae cells

    Science.gov (United States)

    Farzi, Bahman; Cetinkaya, Cetin

    2017-09-01

    The adhesion and mechanical properties of a biological cell (e.g. cell membrane elasticity and adhesiveness) are often strong indicators for the state of its health. Many existing techniques for determining mechanical properties of cells require direct physical contact with a single cell or a group of cells. Physical contact with the cell can trigger complex mechanotransduction mechanisms, leading to cellular responses, and consequently interfering with measurement accuracy. In the current work, based on ultrasonic excitation and interferometric (optical) motion detection, a non-contact method for characterizing the adhesion and mechanical properties of single cells is presented. It is experimentally demonstrated that the rocking (rigid body) motion and internal vibrational resonance frequencies of a single saccharomyces cerevisiae (SC) (baker’s yeast) cell can be acquired with the current approach, and the Young’s modulus and surface tension of the cell membrane as well as surface adhesion energy can be extracted from the values of these acquired resonance frequencies. The detected resonance frequency ranges for single SC cells include a rocking (rigid body) frequency of 330  ±  70 kHz and two breathing resonance frequencies of 1.53  ±  0.12 and 2.02  ±  0.31 MHz. Based on these values, the average work-of-adhesion of SC cells on a silicon substrate in aqueous medium is extracted, for the first time, as WASC-Si=16.2+/- 3.8 mJ {{m}-2} . Similarly, the surface tension and the Young’s modulus of the SC cell wall are predicted as {{σ }SC}=0.16+/- 0.02 N {{m}-1} and {{E}SC}= 9.20  ±  2.80 MPa, respectively. These results are compared to those reported in the literature by utilizing various methods, and good agreements are found. The current approach eliminates the measurement inaccuracies associated with the physical contact. Exciting and detecting cell dynamics at micro-second time-scales is significantly faster than the

  16. Asperity interaction in adhesive contact of metallic rough surfaces

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    The analysis of adhesive contact of metallic rough surfaces considering the effect of asperity interaction is the subject of this investigation. The micro-contact model of asperity interactions developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64) is combined with the elastic plastic adhesive contact model developed by Chang et al (1988 Trans. ASME: J. Tribol. 110 50-6) to consider the asperity interaction and elastic-plastic deformation in the presence of surface forces simultaneously. The well-established elastic adhesion index and plasticity index are used to consider the different contact conditions. Results show that asperity interaction influences the load-separation behaviour in elastic-plastic adhesive contact of metallic rough surfaces significantly and, in general, adhesion is reduced due to asperity interactions

  17. Experimental and theoretical investigations of the adhesion time of Penicillium spores to cedar wood surface

    International Nuclear Information System (INIS)

    Soumya, Elabed; Saad, Ibnsouda Koraichi; Abdellah, Houari; Hassan, Latrache

    2013-01-01

    In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically. Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface. Highlights: ► Calculation of free energy of adhesion to cedar wood of Penicillium by XDLVO approach ► Adhesion is not favorable for all Penicillium spores–cedar wood combinations. ► Adhesion tests demonstrated the ability of Penicillium spores to adhere to cedar wood. ► XDLVO approach correlated well with the results obtained after 3 h of adhesion. ► Discrepancy between XDLVO predictions and experimental observations at 24 h of adhesion

  18. Experimental and theoretical investigations of the adhesion time of Penicillium spores to cedar wood surface

    Energy Technology Data Exchange (ETDEWEB)

    Soumya, Elabed [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Saad, Ibnsouda Koraichi, E-mail: ibnsouda@hotmail.com [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Université Sidi Mohamed Ben Abdellah, Centre Universitaire Régional d' Interface-Fès (Morocco); Abdellah, Houari [Laboratoire de Biotechnologie Microbienne, Faculté des Sciences et Techniques de Fès-Saïs (Morocco); Hassan, Latrache [Laboratoire de Valorisation et de Sécurité des Produits Agroalimentaires, Faculté des Sciences et Techniques de Beni Mellal (Morocco)

    2013-04-01

    In this study, the adhesion of 4 Penicillium strains (Penicillium granulatum, Penicillium crustosum, Penicillium commune and Penicillium chrysogenum) on cedar wood was examined qualitatively and quantitatively by using the extended DLVO (XDLVO) approach and the environmental scanning electronic microscopy (ESEM) technique. A comparison between the XDLVO theories and the ESEM technique was also investigated. The adhesion tests revealed that P. chrysogenum was not able to adhere on the cedar wood substrata, as predicted by the XDLVO approach. We have also found by ESEM that the three Penicillium strains (P. granulatum, P. crustosum, P. commune) adhered on wood, as not predicted theoretically. Moreover, the time of adhesion (3 h and 24 h) was used not only to compare the capacity of adhesion according to contact time but also to explain the discrepancies between the XDLVO approach prediction and the adhesion experiments. A positive relationship between the XDLVO approach and adhesion experiments has been observed after 3 h of adhesion. In contrast, a contradiction between the XDLVO predictions and the adhesion test results has been noted after 24 h of adhesion of Penicillium strains to the wood surface. Highlights: ► Calculation of free energy of adhesion to cedar wood of Penicillium by XDLVO approach ► Adhesion is not favorable for all Penicillium spores–cedar wood combinations. ► Adhesion tests demonstrated the ability of Penicillium spores to adhere to cedar wood. ► XDLVO approach correlated well with the results obtained after 3 h of adhesion. ► Discrepancy between XDLVO predictions and experimental observations at 24 h of adhesion.

  19. Functionalization of CoCr surfaces with cell adhesive peptides to promote HUVECs adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Castellanos, Maria Isabel, E-mail: maria.isabel.castellanos@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Mas-Moruno, Carlos, E-mail: carles.mas.moruno@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Grau, Anna, E-mail: agraugar@gmail.com [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgical Engineering, Technical University of Catalonia (UPC), ETSEIB, 08028 Barcelona (Spain); Centre for Research in Nanoengineering (CRNE), UPC, 08028 Barcelona (Spain); Serra-Picamal, Xavier, E-mail: xserrapicamal@gmail.com [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Trepat, Xavier, E-mail: xtrepat@ub.edu [Institute for Bioengineering of Catalonia (IBEC), 08028 Barcelona (Spain); University of Barcelona and CIBER-BBN, 08036 Barcelona (Spain); Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona (Spain); Albericio, Fernando, E-mail: fernando.albericio@irbbarcelona.org [Department of Chemistry, University of Barcelona, CIBER-BBN, 08028 Barcelona (Spain); Joner, Michael, E-mail: michaeljoner@me.com [Department of Cardiology, Deutsches Herzzentrum München, 80636 Munich (Germany); CVPath Institute, Gaithersburg, MD 20878 (United States); and others

    2017-01-30

    Highlights: • We immobilized peptides on CoCr alloy through physisorption and covalent bonding. • Surface activation is an essential step prior to silanization to enhance peptide attachment. • Biofunctionalized surface characteristics were discussed. • RGDS, YIGSR and combination peptides display an improved HUVECs adhesion and proliferation. - Abstract: Biomimetic surface modification with peptides that have specific cell-binding moieties is a promising approach to improve endothelialization of metal-based stents. In this study, we functionalized CoCr surfaces with RGDS, REDV, YIGSR peptides and their combinations to promote endothelial cells (ECs) adhesion and proliferation. An extensive characterization of the functionalized surfaces was performed by XPS analysis, surface charge and quartz crystal microbalance with dissipation monitoring (QCM-D), which demonstrated the successful immobilization of the peptides to the surface. Cell studies demonstrated that the covalent functionalization of CoCr surfaces with an equimolar combination of RGDS and YIGSR represents the most powerful strategy to enhance the early stages of ECs adhesion and proliferation, indicating a positive synergistic effect between the two peptide motifs. Although these peptide sequences slightly increased smooth muscle cells (SMCs) adhesion, these values were ten times lower than those observed for ECs. The combination of RGDS with the REDV sequence did not show synergistic effects in promoting the adhesion or proliferation of ECs. The strategy presented in this study holds great potential to overcome clinical limitations of current metal stents by enhancing their capacity to support surface endothelialization.

  20. Adhesion of streptococcus rattus and streptococcus mutans to metal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Branting, C.; Linder, L.E.; Sund, M.-L.; Oden, A.; Wiatr-Adamczak, E.

    1988-01-01

    The adhesion of Streptococcus rattus BHT and Streptococcus mutans IB to metal specimens of amalgam, silver, tin and copper was studied using (6-/sup 3/H) thymidine labeled cells. In the standard assay the metal specimens were suspended by a nylon thread in an adhesion solution containing a chemically defined bacterial growth medium (FMC), sucrose, and radiolabeled bacteria. Maximum amounts of adhering bacteria were obtained after about 100 min of incubation. Saturation of the metal specimens with bacteria was not observed. Both strains also adhered in the absence of sucrose, indicating that glucan formation was not necessary for adhesion. However, in the presence of glucose, adhesion was only 26-45% of that observed in the presence of equimolar sucrose. Sucrose-dependent stimulation of adhesion seemed to be due to increased cell-to-cell adhesion capacity. Isolated radiolabeled water-insoluble and water-soluble polysaccharides produced from sucrose by S. rattus BHT were not adsorbed to the metal surfaces.

  1. Adhesion of streptococcus rattus and streptococcus mutans to metal surfaces

    International Nuclear Information System (INIS)

    Branting, C.; Linder, L.E.; Sund, M.-L.; Oden, A.; Wiatr-Adamczak, E.

    1988-01-01

    The adhesion of Streptococcus rattus BHT and Streptococcus mutans IB to metal specimens of amalgam, silver, tin and copper was studied using (6- 3 H) thymidine labeled cells. In the standard assay the metal specimens were suspended by a nylon thread in an adhesion solution containing a chemically defined bacterial growth medium (FMC), sucrose, and radiolabeled bacteria. Maximum amounts of adhering bacteria were obtained after about 100 min of incubation. Saturation of the metal specimens with bacteria was not observed. Both strains also adhered in the absence of sucrose, indicating that glucan formation was not necessary for adhesion. However, in the presence of glucose, adhesion was only 26-45% of that observed in the presence of equimolar sucrose. Sucrose-dependent stimulation of adhesion seemed to be due to increased cell-to-cell adhesion capacity. Isolated radiolabeled water-insoluble and water-soluble polysaccharides produced from sucrose by S. rattus BHT were not adsorbed to the metal surfaces. (author)

  2. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement

    Science.gov (United States)

    Maier, Greg P.; Rapp, Michael V.; Waite, J. Herbert; Israelachvili, Jacob N.; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (Ead ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a “one-two punch,” whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides.

  3. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    Science.gov (United States)

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation.

  4. Adhesion of Chlamydomonas microalgae to surfaces is switchable by light

    Science.gov (United States)

    Kreis, Christian Titus; Le Blay, Marine; Linne, Christine; Makowski, Marcin Michal; Bäumchen, Oliver

    2018-01-01

    Microalgae are photoactive microbes that live in liquid-infused environments, such as soil, temporary pools and rocks, where they encounter and colonize a plethora of surfaces. Their photoactivity manifests itself in a variety of processes, including light-directed motility (phototaxis), the growth of microalgal populations, and their photosynthetic machinery. Although microbial responses to light have been widely recognized, any influence of light on cell-surface interactions remains elusive. Here, we reveal that the unspecific adhesion of microalgae to surfaces can be reversibly switched on and off by light. Using a micropipette force spectroscopy technique, we measured in vivo single-cell adhesion forces and show that the microalga's flagella provide light-switchable adhesive contacts with the surface. This light-induced adhesion to surfaces is an active and completely reversible process that occurs on a timescale of seconds. Our results suggest that light-switchable adhesiveness is a natural functionality of microalgae to regulate the transition between the planktonic and the surface-associated state, which yields an adhesive adaptation to optimize the photosynthetic efficiency in conjunction with phototaxis.

  5. Adhesion, Deformation, Rolling, and Detachment of a Liquid Capsule on An Adhesive Surface In Shear Flow

    Science.gov (United States)

    Pappu, Vijay; Bagchi, Prosenjit

    2008-11-01

    3D computational modeling and simulation are presented on adhesion, deformation, rolling and detachment of a liquid capsule on adhesive surfaces in shear flow with an objective to understand the adhesive rolling motion of biological cells, such as leukocyte and cancel cells, and the coupling between cell deformation and biophysics of the adhesive bonds. The computational model is based on an immersed boundary method for deformable capsules, and a finite difference-Fourier transform technique for solving the complete Navier-Stokes equations. The flow solver is coupled with a Monte Carlo simulation representing random process for bond formation and breakage between the capsule and the adhesive surface. Becuase of the stochastic process of bond formation and breakage, the roling motion is comprised of intermittent ``stops-and-runs'' which is well-known for biological cells such as leukocytes, which is reproduced in our simulations. The major objective of this talk is to present phase diagrams for cell adhesion which are obtained in terms of the critical bond strength as a function of cell deformability and biophysical parameters of the adhesion bonds. Through these phase diagrams, we elucidate the role of the hydrodynamic lift force, that exists on an wall- bounded deformable particle in shear flow, in the process of cell capture. Funded by NSF (BES-0603035 and CTS-0625936).

  6. Stability analysis of rough surfaces in adhesive normal contact

    Science.gov (United States)

    Rey, Valentine; Bleyer, Jeremy

    2018-03-01

    This paper deals with adhesive frictionless normal contact between one elastic flat solid and one stiff solid with rough surface. After computation of the equilibrium solution of the energy minimization principle and respecting the contact constraints, we aim at studying the stability of this equilibrium solution. This study of stability implies solving an eigenvalue problem with inequality constraints. To achieve this goal, we propose a proximal algorithm which enables qualifying the solution as stable or unstable and that gives the instability modes. This method has a low computational cost since no linear system inversion is required and is also suitable for parallel implementation. Illustrations are given for the Hertzian contact and for rough contact.

  7. Motion of Elastic Microcapsules on Compliant Surfaces with Adhesive Ligands

    Science.gov (United States)

    Maresov, Egor; Kolmakov, German; Balazs, Anna

    2011-03-01

    By integrating mesoscale models for hydrodynamics, micromechanics and adhesion, we examine the fluid driven motion of elastic microcapsules on compliant surfaces. The capsules, modeled as three-dimensional fluid-filled elastic shells, represent polymeric microcapsules or biological cells. Our combined integrated Lattice Boltzmann model/Lattice spring model (LBM/LSM) approach allows for a dynamic interaction between the elastic capsule's wall and surrounding fluid. To capture the interaction between the shell and the surface, we adopt the Bell model, used previously to describe the interaction of biological cell like leukocytes rolling on surfaces under the influence of an imposed shear. The surface of the microcapsule contains receptors with an affinity to adhesive ligands of the substrate. We examine how the parameters of adhesion and rigidity of the capsules and the substrate affect movement of the capsules. The findings provide guidelines for creating smart surfaces that could regulate the microcapsules' motion.

  8. Effect of surface cleanliness of aluminium substrates on silicone rubber adhesion

    OpenAIRE

    Petersson, L; Meier, P; Kornmann, X; Hillborg, H

    2011-01-01

    ABSTRACT The aim of the present work was to determine the minimum surface cleanliness of aluminum substrates required for good and reproducible silicone rubber adhesion. Aluminum substrates were prepared, ranging from 'contaminated ' to different degrees of 'cleaned '. The surface energy of the substrates was determined by contact angle measurements. The surfaces were also compared using simplified methods, such as a wettability test or by the use of inks with known surface tension. Silico...

  9. Primary Adhesion in Enteromorpha. Cue Detection and Surface Selection in the Settlement and Adhesion of Enteromorpha Spores

    National Research Council Canada - National Science Library

    Callow, James

    2001-01-01

    .... spore settlement and adhesion. Our results provide the most comprehensive characterisation of the settlement and adhesion processes and the roles of surface-associated cues, of any soft-fouling species to date, We have shown...

  10. Adhesion of Spores of Bacillus thuringiensis on a Planar Surface

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Eunhyea [Georgia Institute of Technology; Kweon, Hyojin [Georgia Institute of Technology; Yiacoumi, Sotira [Georgia Institute of Technology; Lee, Ida [University of Tennessee, Knoxville (UTK); Joy, David Charles [ORNL; Palumbo, Anthony Vito [ORNL; Tsouris, Costas [ORNL

    2010-01-01

    Adhesion of spores of Bacillus thuringiensis (Bt) and spherical silica particles on surfaces was experimentally and theoretically investigated in this study. Topography analysis via atomic force microscopy (AFM) and electron microscopy indicates that Bt spores are rod shaped, {approx}1.3 {mu}m in length and {approx}0.8 {mu}m in diameter. The adhesion force of Bt spores and silica particles on gold-coated glass was measured at various relative humidity (RH) levels by AFM. It was expected that the adhesion force would vary with RH because the individual force components contributing to the adhesion force depend on RH. The adhesion force between a particle and a planar surface in atmospheric environments was modeled as the contribution of three major force components: capillary, van der Waals, and electrostatic interaction forces. Adhesion force measurements for Bt spore (silica particle) and the gold surface system were comparable with calculations. Modeling results show that there is a critical RH value, which depends on the hydrophobicity of the materials involved, below which the water meniscus does not form and the contribution of the capillary force is zero. As RH increases, the van der Waals force decreases while the capillary force increases to a maximum value.

  11. Observation of optimal gecko's adhesion on nanorough surfaces.

    Science.gov (United States)

    Pugno, Nicola M; Lepore, Emiliano

    2008-12-01

    In this letter we report experimental observations on the times of adhesion of living Tokay geckos (Gekko geckos) on polymethylmethacrylate (PMMA) inverted surfaces. Two different geckos (male and female) and three surfaces with different root mean square (RMS) roughness (RMS=42, 618 and 931 nm) have been considered, for a total of 72 observations. The measured data are proved to be statistically significant, following the Weibull Statistics with coefficients of correlation between 0.781 and 0.955. The unexpected result is the observation of a maximal gecko adhesion on the surface with intermediate roughness of RMS=618 nm, that we note has waviness comparable to the seta size.

  12. Electric double layer interactions in bacterial adhesion to surfaces

    NARCIS (Netherlands)

    Poortinga, AT; Norde, W; Busscher, HJ; Bos, R.R.M.

    2002-01-01

    The DLVO (Derjaguin, Landau, Verwey, Overbeek) theory was originally developed to describe interactions between non-biological lyophobic colloids such as polystyrene particles, but is also used to describe bacterial adhesion to surfaces. Despite the differences between the surface of bacteria and

  13. Effect of Viscoelasticity on Adhesion of Bioinspired Micropatterned Epoxy Surfaces

    NARCIS (Netherlands)

    Castellanos, G.; Arzt, E.; Kamperman, M.M.G.

    2011-01-01

    The effect of viscoelasticity on adhesion was investigated for micropatterned epoxy surfaces and compared to nonpatterned surfaces. A two-component epoxy system was used to produce epoxy compositions with different viscoelastic properties. Pillar arrays with flat punch tip geometries were fabricated

  14. Enhancing structural integrity of adhesive bonds through pulsed laser surface micro-machining

    KAUST Repository

    Diaz, Edwin Hernandez

    2015-06-01

    Enhancing the effective peel resistance of plastically deforming adhesive joints through laser-based surface micro-machining Edwin Hernandez Diaz Inspired by adhesion examples commonly found in nature, we reached out to examine the effect of different kinds of heterogeneous surface properties that may replicate this behavior and the mechanisms at work. In order to do this, we used pulsed laser ablation on copper substrates (CuZn40) aiming to increase adhesion for bonding. A Yb-fiber laser was used for surface preparation of the substrates, which were probed with a Scanning Electron Microscope (SEM) and X-ray Photoelectron Spectroscopy (XPS). Heterogeneous surface properties were devised through the use of simplified laser micromachined patterns which may induce sequential events of crack arrest propagation, thereby having a leveraging effect on dissipation. The me- chanical performance of copper/epoxy joints with homogeneous and heterogeneous laser micromachined interfaces was then analyzed using the T-peel test. Fractured surfaces were analyzed using SEM to resolve the mechanism of failure and adhesive penetration within induced surface asperities from the treatment. Results confirm positive modifications of the surface morphology and chemistry from laser ablation that enable mechanical interlocking and cohesive failure within the adhesive layer. Remarkable improvements of apparent peel energy, bond toughness, and effective peel force were appreciated with respect to sanded substrates as control samples.

  15. Work of adhesion of dairy products on stainless steel surface

    Directory of Open Access Journals (Sweden)

    Patrícia Campos Bernardes

    2012-12-01

    Full Text Available The adhesion of the solids presents in food can difficult the process of surface cleaning and promotes the bacterial adhesion process and can trigger health problems. In our study, we used UHT whole milk, chocolate based milk and infant formula to evaluate the adhesion of Enterobacter sakazakii on stainless steel coupons, and we determine the work of adhesion by measuring the contact angle as well as measured the interfacial tension of the samples. Inaddition we evaluated the hydrophobicity of stainless steel after pre-conditioning with milk samples mentioned. E. sakazakii was able to adhere to stainless steel in large numbers in the presence of dairy products. The chocolate based milk obtained the lower contact angle with stainless steel surface, higher interfacial tension and consequently higher adhesion work. It was verified a tendency of decreasing the interfacial tension as a function of the increasing of protein content. The pre-conditioning of the stainless steel coupons with milk samples changed the hydrophobic characteristics of the surfaces and became them hydrophilic. Therefore, variations in the composition of the milk products affect parameters important that can influence the procedure of hygiene in surface used in food industry.

  16. Transience of plasma surface modification as an adhesion promoter for polychlorotrifluorethylene

    CERN Document Server

    Subramanian, S; Love, B J; Romand, M; Charbonnier, M

    2002-01-01

    Poly(chlorotrifluoroethylene) (PCTFE) and other fluoropolymers are increasingly used as inner layer dielectrics. However, these polymers have low surface energies and correspondingly poor adhesive properties. Results are presented on the use of a low-pressure ammonia plasma to enhance the surface bondability of PCTFE. The plasma modified PCTFE film surfaces were characterized by x-ray photoelectron spectroscopy and contact angle measurements. Surface modified films exhibited improved adhesion to electroless copper deposits (180 deg. peel test) compared to coated PCTFE controls and that underwent no plasma exposure. Annealing studies were conducted between 30 and 100 deg. C to examine the stability of the plasma-modified surfaces. For samples annealed below T sub g , contact angle measurements indicated that the plasma-introduced groups remained bound on the surface for four weeks. For specimens annealed above T sub g , the surface functionalities were absorbed within the bulk and surface rearrangement occurre...

  17. IMPLICATIONS OF MICROBIAL ADHESION TO HYDROCARBONS FOR EVALUATING CELL-SURFACE HYDROPHOBICITY .2. ADHESION MECHANISMS

    NARCIS (Netherlands)

    VANDERMEI, HC; VANDEBELTGRITTER, B; BUSSCHER, HJ

    1995-01-01

    Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. Recent observations that the zeta potentials of hydrocarbons can be highly negative in the various solutions commonly used in MATH, have suggested that MATH may measure a

  18. Surface adhesion and its dependence on surface roughness and humidity measured with a flat AFM tip

    NARCIS (Netherlands)

    Colak, A.; Wormeester, Herbert; Zandvliet, Henricus J.W.; Poelsema, Bene

    2012-01-01

    The adhesion force between a surface and the tip of an atomic force microscope cantilever has been determined by recording force–distance curves with an atomic force microscope. Flat tips with a diameter of 2 μm were used to mimic the adhesion between two parallel surfaces. In such a configuration,

  19. Study on surface adhesion of Plasma modified Polytetrafluoroethylene hollow fiber membrane

    Science.gov (United States)

    Chen, Jiangrong; Zhang, Huifeng; Liu, Guochang; Guo, Chungang; Lv, Jinglie; Zhangb, Yushan

    2018-01-01

    Polytetrafluoroethylene (PTFE) is popular membrane material because of its excellent thermal stability, chemical stability and mechanical stability. However, the low surface energy and non-sticky property of PTFE present challenges for modification. In the present study, plasma treatment was performed to improve the surface adhesion of PTFE hollow fiber membrane. The effect of discharge voltage, treatment time on the adhesion of PTFE hollow fiber membrane was symmetrically evaluated. Results showed that the plasma treatment method contributed to improve the surface activity and roughness of PTFE hollow fiber membrane, and the adhesion strength depend significantly on discharge voltage, which was beneficial to seepage pressure of PTFE hollow fiber membrane module. The adhesion strength of PTFE membrane by plasma treated at 220V for 3min reached as high as 86.2 N, far surpassing the adhesion strength 12.7 N of pristine membrane. Furthermore, improvement of content of free radical and composition analysis changes of the plasma modified PTFE membrane were investigated. The seepage pressure of PTFE membrane by plasma treated at 220V for 3min was 0.375 MPa, which means that the plasma treatment is an effective technique to improve the adhesion strength of membrane.

  20. Surface science. Adhesion and friction in mesoscopic graphite contacts.

    Science.gov (United States)

    Koren, Elad; Lörtscher, Emanuel; Rawlings, Colin; Knoll, Armin W; Duerig, Urs

    2015-05-08

    The weak interlayer binding in two-dimensional layered materials such as graphite gives rise to poorly understood low-friction characteristics. Accurate measurements of the adhesion forces governing the overall mechanical stability have also remained elusive. We report on the direct mechanical measurement of line tension and friction forces acting in sheared mesoscale graphite structures. We show that the friction is fundamentally stochastic in nature and is attributable to the interaction between the incommensurate interface lattices. We also measured an adhesion energy of 0.227 ± 0.005 joules per square meter, in excellent agreement with theoretical models. In addition, bistable all-mechanical memory cell structures and rotational bearings have been realized by exploiting position locking, which is provided solely by the adhesion energy. Copyright © 2015, American Association for the Advancement of Science.

  1. Platelet adhesion studies on dipyridamole coated polyurethane surfaces

    Directory of Open Access Journals (Sweden)

    Aldenhoff Y. B.J.

    2003-06-01

    Full Text Available Surface modification of polyurethanes (PUs by covalent attachment of dipyridamole (Persantinregistered is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP. This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exteriour surface.

  2. Laser Surface Preparation for Adhesive Bonding of Aerospace Structural Composites

    Science.gov (United States)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.

    2010-01-01

    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical pre-bonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  3. Shewanella putrefaciens adhesion and biofilm formation on food processing surfaces

    DEFF Research Database (Denmark)

    Bagge, Dorthe; Hjelm, M.; Johansen, C.

    2001-01-01

    of bacteria on the surface must be quantified to evaluate the influence of environmental factors on adhesion and biofilm formation. We used a combination of fluorescence microscopy (4',6'-diamidino-2-phenylindole staining and in situ hybridization, for mixed-culture studies), ultrasonic removal of bacteria...

  4. Characterization of neutrophil adhesion to different titanium surfaces

    Indian Academy of Sciences (India)

    ing blood; however, direct contact between the oxide layer of the implant and neutrophils has not been completely described. The aim of the present study is to compare ... Titanium surfaces; neutrophil morphology; adhesion molecules; inflammatory response; flow cytome- try; scanning electron microscopy. 1. Introduction.

  5. Adhesion of Photoactive Microalgae to Surfaces is Switchable by Light

    Science.gov (United States)

    Bäumchen, Oliver; Kreis, Christian; Le Blay, Marine; Linne, Christine; Makowski, Marcin

    The natural habitats of many microorganisms are confined geometries, such as the interstitial space of rocks and soil, where interactions with interfaces and surfaces are of paramount importance. We performed in vivo force spectroscopy experiments on the unicellular biflagellated microalga Chlamydomonas, a prime model organism in cell- and microbiology, and discovered that the flagella-mediated adhesion to surfaces can be switched on and off by light. Time-resolved micropipette experiments show that the light-switchable adhesiveness of the flagella is a completely reversible process that is based on a redistribution of adhesion-promoting flagella-membrane proteins within seconds. Light-switchable adhesion enables the cell to regulate the transition between planktonic and surface-associated state, which possibly represents a significant biological advantage for photoactive microorganisms. In terms of the colonization of surfaces and the formation of biofilms, the findings might have immediate economic and environmental relevance in biotechnological settings, such as photo-bioreactors for the sustainable production of biofuels.

  6. Effective macroscopic adhesive contact behavior induced by small surface roughness

    Science.gov (United States)

    Kesari, Haneesh; Lew, Adrian J.

    2011-12-01

    In this paper we study a model contact problem involving adhesive elastic frictionless contact between rough surfaces. The problem's most notable feature is that it captures the phenomenon of depth-dependent-hysteresis (DDH) (e.g., see Kesari et al., 2010), which refers to the observation of different contact forces during the loading and unloading stages of a contact experiment. We specifically study contact between a rigid axi-symmetric punch and an elastic half-space. The roughness is represented as arbitrary periodic undulations in the punch's radial profile. These undulations induce multiple equilibrium contact regions between the bodies at each indentation-depth. Assuming that the system evolves so as to minimize its potential energy, we show that different equilibrium contact regions are selected during the loading and unloading stages at each indentation-depth, giving rise to DDH. When the period and amplitude of our model's roughness is reduced, we show that the evolution of the contact force and radius with the indentation-depth can be approximated with simpler curves, the effective macroscopic behavior, which we compute. Remarkably, the effective behavior depends solely on the amplitude and period of the model's roughness. The effective behavior is useful for estimating material properties from contact experiments displaying DDH. We show one such example here. Using the effective behavior for a particular roughness model (sinusoidal) we analyze the energy loss during a loading/unloading cycle, finding that roughness can toughen the interface. We also estimate the energy barriers between the different equilibrium contact regions at a fixed indentation-depth, which can be used to assess the importance of ambient energy fluctuations on DDH.

  7. A kit for the investigation of live Escherichia coli cell adhesion to glycosylated surfaces

    DEFF Research Database (Denmark)

    Hartmann, M.; Horst, A. K.; Klemm, Per

    2010-01-01

    A combination of microtiter plate functionalization techniques and two facile bacterial adhesion inhibition assays form a flexible toolbox for the investigation of bacterial adhesion mechanisms on glycosylated surfaces.......A combination of microtiter plate functionalization techniques and two facile bacterial adhesion inhibition assays form a flexible toolbox for the investigation of bacterial adhesion mechanisms on glycosylated surfaces....

  8. Contact studies of weak adhesive interactions in water with membrane enhanced surface acoustic wave analysis

    Science.gov (United States)

    Brass, David Alan

    The measurement of weak adhesive energies has previously been difficult to obtain. To measure these energies, I designed a technique that uses the combined sensitivities of both a quartz crystal resonator and the inflation of an elastomeric polymer membrane. The surfaces of the quartz crystal and/or the membrane are modified with water swollen polymer brushes, which are used to eliminate nonspecific adhesion. These brushes are then end-modified with adhesive functional groups. An analysis is developed for the frequency response of a quartz crystal resonator as the membrane layer is placed in contact with the surface of these swollen brushes. The shear wave generated at the resonator surface couples into the membrane layer with an efficiency that is strongly dependent on the thickness of the swollen brush layer. The calculated shift decreases substantially for increases in the brush thickness of ten to twenty nanometers, giving a net frequency response that is extremely sensitive to the degree of swelling of the brush. An optimum capping layer thickness is determined by balancing the resonant frequency shift against dissipative effects that weaken the crystal resonance. Detailed calculations are presented for the specific case of poly(ethylene glycol) (PEG) brushes swollen by water and capped by a poly(styrene-ethylene/butene-styrene) (SEBS) elastomeric, water-permeable membrane. These calculations show that the method is sensitive to the properties of the brush layer. This surface acoustic wave technique was coupled with an inflation method that enabled quantification of the adhesion between the membrane and the brush coated surface. This adhesive interaction is obtained from the contact angle made between the quartz and membrane surfaces and the tension on the membrane. An analysis of the membrane profile based on the numerical solution of the axisymmetric Laplace equation is developed and used to investigate both adhesive and non-adhesive situations with both an

  9. Design methodology for nano-engineered surfaces to control adhesion: Application to the anti-adhesion of particles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taekyung [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of); Min, Cheongwan [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); Jung, Myungki; Lee, Jinhyung; Park, Changsu [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of); Kang, Shinill, E-mail: snlkang@yonsei.ac.kr [National Center for Optically-Assisted Ultra-High Precision Mechanical Systems, Yonsei University, Seoul 03722 (Korea, Republic of); School of Mechanical Engineering, Yonsei University, Seoul 03722 (Korea, Republic of)

    2016-12-15

    Highlights: • A design method using the Derjaguin approximation with FEA for low-adhesion surface. • Fabrication of nanostructures with small adhesion forces by presented design method. • Characterization of adhesion force via AFM FD-curve with modified atypical tips. • Verification of low-adhesion of designed surfaces using centrifugal detachment tests. • Investigation of interdependence of hydrophobicity and anti-adhesion force. - Abstract: With increasing demand for means of controlling surface adhesion in various applications, including the semiconductor industry, optics, micro/nanoelectromechanical systems, and the medical industry, nano-engineered surfaces have attracted much attention. This study suggests a design methodology for nanostructures using the Derjaguin approximation in conjunction with finite element analysis for the control of adhesion forces. The suggested design methodology was applied for designing a nano-engineered surface with low-adhesion properties. To verify this, rectangular and sinusoidal nanostructures were fabricated and analyzed using force-distance curve measurements using atomic force microscopy and centrifugal detachment testing. For force-distance curve measurements, modified cantilevers with tips formed with atypical particles were used. Subsequently, centrifugal detachment tests were also conducted. The surface wettability of rectangular and sinusoidal nanostructures was measured and compared with the measured adhesion force and the number of particles remaining after centrifugal detachment tests.

  10. Electrochemical determination of the onset of bacterial surface adhesion

    Science.gov (United States)

    Jones, Akhenaton-Andrew; Buie, Cullen

    2017-11-01

    Microbial biofouling causes economic loss through corrosion and drag losses on ship hulls, and in oil and food distribution. Microorganisms interacting with surfaces under these open channel flows contend with high shear rates and active transport to the surface. The metallic surfaces they interact with carry charge at various potentials that are little addressed in literature. In this study we demonstrate that the Levich curve, chronoamperometry, and cyclic voltammetry in a rotating disk electrode are ideal for studying adhesion of microbes to metallic surfaces. We study the adhesion of Escherichia coli, Bacillus subtilis, and 1 μm silica microspheres over a 0.15 - 37.33 dynes .cm-2 or shear rates of 14.73 - 3727.28 s-1 range. Our results agree with literature on red blood cells in rotating disk electrodes, deposition rates from optical systems, and show that we can quantify changes in active electrode area by bacteria adhesion and protein secretion. These methods measure changes in area instead of mass, are more accurate than fluorescence microscopy, and apply to a larger range of problems than on-chip flow devices.

  11. Effect of surface cleanliness of aluminium substrates on silicone rubber adhesion

    Science.gov (United States)

    Petersson, L.; Meier, P.; Kornmann, X.; Hillborg, H.

    2011-01-01

    The aim of this work was to determine the minimum surface cleanliness of aluminium substrates required for good and reproducible silicone rubber adhesion. Aluminium substrates were prepared, ranging from 'contaminated' to different degrees of 'cleaned'. The surface energy of the substrates was determined by contact angle measurements. The surfaces were also compared using simplified methods, such as a wettability test or by the use of inks with known surface tension. Silicone rubber was then compression moulded onto the cleaned and primed substrates. The silicone rubber adhesion was then evaluated by lap-shear testing, before and after ageing. The ageing step consisted of immersion of samples in boiling water for 100 h to evaluate the hydrolytic stability of the interfaces. The failure modes after lap-shear testing were determined using optical microscopy and scanning electron microscopy and were divided into three different categories: cohesive failure, adhesive failure or a mixture thereof. Energy dispersive x-ray mapping was useful in clarifying the failure modes by determining the position of the primer, which contained Ti. It was concluded that in order to obtain a strong and stable interface, exhibiting mainly cohesive failure between the aluminium substrate and silicone rubber, the surface energy of the substrate before priming should be >45 mJ m-2, including a polar component of >10 mJ m-2. This corresponded to a hydrophobicity class of the substrate of >=6, according to IEC 62073.

  12. Surface adhesion and confinement variation of Staphylococcus aurius on SAM surfaces

    Science.gov (United States)

    Amroski, Alicia; Olsen, Morgan; Calabrese, Joseph; Senevirathne, Reshani; Senevirathne, Indrajith

    2012-02-01

    Controlled surface adhesion of non - pathogenic gram positive strain, Staphylococcus aureus is interesting as a model system due to possible development of respective biosensors for prevention and detection of the pathogenic strain methicillin resistant Staphylococcus aureus (MRSA) and further as a study for bio-machine interfacing. Self Assembled Monolayers (SAM) with engineered surfaces of linear thiols on Au(111) were used as the substrate. Sub cultured S. aureus were used for the analysis. The SAM layered surfaces were dipped in 2 -- 4 Log/ml S. aureus solution. Subsequent surface adhesion at different bacterial dilutions on surfaces will be discussed, and correlated with quantitative and qualitative adhesion properties of bacteria on the engineered SAM surfaces. The bacteria adhered SAM surfaces were investigated using intermittent contact, noncontact, lateral force and contact modes of Atomic Force Microscopy (AFM).

  13. The role of adhesion energy in controlling cell?cell contacts

    OpenAIRE

    Ma?tre, Jean-L?on; Heisenberg, Carl-Philipp

    2011-01-01

    Recent advances in microscopy techniques and biophysical measurements have provided novel insight into the molecular, cellular and biophysical basis of cell adhesion. However, comparably little is known about a core element of cell?cell adhesion?the energy of adhesion at the cell?cell contact. In this review, we discuss approaches to understand the nature and regulation of adhesion energy, and propose strategies to determine adhesion energy between cells in vitro and in vivo.

  14. Effect of Er:YAG laser energy on the morphology of enamel/adhesive system interface

    Science.gov (United States)

    Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Pécora, Jesus Djalma; Palma-Dibb, Regina Guenka

    2006-10-01

    The aim of this study was to evaluate in vitro the influence of Er:YAG laser energy variation to cavity preparation on the morphology of enamel/adhesive system interface, using SEM. Eighteen molars were used and the buccal surfaces were flattened without dentine exposure. The specimens were randomly assigned to two groups, according to the adhesive system (conventional total-etching or self-etching), and each group was divided into three subgroups (bur carbide in turbine of high rotation, Er:YAG laser 250 mJ/4 Hz and Er:YAG laser 300 mJ/4 Hz) containing six teeth each. The enamel/adhesive system interface was serially sectioned and prepared for SEM. The Er:YAG laser, in general, produced a more irregular adhesive interface than the control group. For Er:YAG laser 250 mJ there was formation of a more regular hybrid layer with good tag formation, mainly in the total-etching system. However, Er:YAG laser 300 mJ showed a more irregular interface with amorphous enamel and fused areas, for both adhesive systems. It was concluded that cavity preparation with Er:YAG laser influenced on the morphology of enamel/adhesive system interface and the tissual alterations were more evident when the energy was increased.

  15. Novel Epoxy Particulate Composites for Mitigation of Insect Residue Adhesion on Future Aircraft Surfaces

    Science.gov (United States)

    Wohl, Christopher J.; Smith, Joseph G., Jr.; Gardner, John M.; Penner, Ronald K.; Connell, John W.; Siochi, Emilie J.

    2014-01-01

    Drag is reduced significantly for airflow over surfaces when laminar flow can be maintained over greater chord lengths, the distance from the leading edge of an airfoil.1 However, surface imperfections, such as chipped paint, scratches, and events that change topography on a microscopic scale can introduce airflow instabilities resulting in premature transition to turbulent flow.1 Although many of these surface imperfections can be avoided with proper maintenance, advanced materials, and advanced manufacturing practices, topographical surface anomalies arising during flight from insect impacts cannot be controlled and can influence laminar flow stability. Practical solutions to this operational challenge need to be developed for future aircraft to have full advantage of laminar flow designs that improve fuel efficiency.2 Researchers have investigated various methods to mitigate insect residue adhesion for decades.3 Although several techniques have demonstrated efficacy including mechanical scrapers, active liquid discharge systems, and sacrificial paper coatings, they have not been commercially implemented due to increased manufacturing and operational complexity, environmental impact, and weight penalties. Coatings offer a simple route for passive insect residue adhesion prevention without many of the challenges associated with maintenance of laminar flow.4 In our previous work, we determined that most commercially available materials were not effective at insect residue adhesion.5 We also identified improvements when both surface energy could be controlled by surface modifying agents and the topography could be altered through the use of micron-sized and nanometer-sized filler materials.6 In this work, these general principles were applied to an epoxy system to evaluate the behavior of the surface modifying agent, a fluorinated alkyl ether oligomer, on surface energy and insect residue adhesion properties.

  16. Effects of some chemical surface modifications on resin zirconia adhesion.

    Science.gov (United States)

    Liu, Dan; Tsoi, James Kit-Hon; Matinlinna, Jukka Pekka; Wong, Hai Ming

    2015-06-01

    To evaluate the effects of various chemical surface modifications on adhesion between zirconia and resin adhesive. Pre-sintered zirconia discs were sectioned from commercial cylindrical blocks and polished with abrasive papers under running tap water. All the discs were randomly divided into five study groups according to the methods of surface treatment, including: the control group (fully sintered, without any modification), group S (fully sintered and sandblasted with silica coated alumina particles), group HN (fully sintered and etched with a blend of mineral acid solution at 100 °C for 25 min), group HF (fully sintered and etched with 48% hydrofluoric acid solution at 100 °C for 25 min), and group Si (coated with silica particles and then fully sintered). The mean value of surface roughness was evaluated before further treatment. Resin stubs (3.6mm in diameter and 3mm in height) were adhered and light cured on each zirconia disc after the application of a silane coupling agent. In each group, all the samples were further divided into three subgroups with each n=12, one for the measurement of initial adhesion strength (shear bond) value and the other two were tested after thermal cycling for 10,000 and 20,000 cycles, respectively. The results were analyzed with two-way ANOVA and Turkey HSD (pzirconia surface crystallinity. The morphological appearance of zirconia surface after surface treatment was observed with SEM. The control group showed the lowest initial shear bond strength (SBS) value (16.8 ± 2.4 MPa) and did not survive the aging treatments. All the investigated surface treatments improved resin zirconia bond strength significantly, the group S displaying the highest initial value of 25.1 ± 2.7 MPa. However, the highest resistance to the aging effects of thermal cycling was found in group Si. It was further shown in the XRD examination that only the grit-blasting caused the crystalline transformation from tetragonal phase to monoclinic phase (T

  17. Plasma Electrolytic Oxidation of Titanium Implant Surfaces: Microgroove-Structures Improve Cellular Adhesion and Viability.

    Science.gov (United States)

    Hartjen, Philip; Hoffmann, Alexia; Henningsen, Anders; Barbeck, Mike; Kopp, Alexander; Kluwe, Lan; Precht, Clarissa; Quatela, Olivia; Gaudin, Robert; Heiland, Max; Friedrich, Reinhard E; Knipfer, Christian; Grubeanu, Daniel; Smeets, Ralf; Jung, Ole

    2018-01-01

    Plasma electrolytic oxidation (PEO) is an established electrochemical treatment technique that can be used for surface modifications of metal implants. In this study we to treated titanium implants with PEO, to examine the resulting microstructure and to characterize adhesion and viability of cells on the treated surfaces. Our aim was to identify an optimal surface-modification for titanium implants in order to improve soft-tissue integration. Three surface-variants were generated on titanium alloy Ti6Al4V by PEO-treatment. The elemental composition and the microstructures of the surfaces were characterized using energy dispersive X-ray spectroscopy, scanning electron microscopy and profilometry. In vitro cytocompatibility of the surfaces was assessed by seeding L929 fibroblasts onto them and measuring the adhesion, viability and cytotoxicity of cells by means of live/dead staining, XTT assay and LDH assay. Electron microscopy and profilometry revealed that the PEO-surface variants differed largely in microstructure/topography, porosity and roughness from the untreated control material as well as from one another. Roughness was generally increased after PEO-treatment. In vitro, PEO-treatment led to improved cellular adhesion and viability of cells accompanied by decreased cytotoxicity. PEO-treatment provides a promising strategy to improve the integration of titanium implants with surrounding tissues. Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  18. Clays causing adhesion with tool surfaces during mechanical tunnel driving

    Science.gov (United States)

    Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

    2009-04-01

    During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

  19. Brain surface motion imaging to predict adhesions between meningiomas and the brain surface

    Energy Technology Data Exchange (ETDEWEB)

    Taoka, Toshiaki; Yamatani, Yuya; Akashi, Toshiaki; Miyasaka, Toshiteru; Emura, Tomoko; Kichikawa, Kimihiko [Nara Medical University, Department of Radiology, Nara (Japan); Yamada, Syuichi; Nakase, Hiroyuki [Nara Medical University, Department of Neurosurgery, Nara (Japan)

    2010-11-15

    ''Brain surface motion imaging'' (BSMI) is the subtraction of pulse-gated, 3D, heavily T2-weighted image of two different phases of cerebrospinal fluid (CSF) pulsation, which enables the assessment of the dynamics of brain surface pulsatile motion. The purpose of this study was to evaluate the feasibility of this imaging method for providing presurgical information about adhesions between meningiomas and the brain surface. Eighteen cases with surgically resected meningioma in whom BSMI was presurgically obtained were studied. BSMI consisted of two sets of pulse-gated, 3D, heavily T2-weighted, fast spin echo scans. Images of the systolic phase and the diastolic phase were obtained, and subtraction was performed with 3D motion correction. We analyzed the presence of band-like texture surrounding the tumor and judged the degree of motion discrepancy as ''total,'' ''partial,'' or ''none.'' The correlation between BSMI and surgical findings was evaluated. For cases with partial adhesions, agreements in the locations of the adhesions were also evaluated. On presurgical BSMI, no motion discrepancy was seen in eight cases, partial in six cases, and total in four cases. These presurgical predictions about adhesions and surgical findings agreed in 13 cases (72.2%). The locations of adhesions agreed in five of six cases with partial adhesions. In the current study, BSMI could predict brain and meningioma adhesions correctly in 72.2% of cases, and adhesion location could also be predicted. This imaging method appears to provide presurgical information about brain/meningioma adhesions. (orig.)

  20. Micro-Pattern Guided Adhesion of Osteoblasts on Diamond Surfaces

    Directory of Open Access Journals (Sweden)

    Marie Kalbacova

    2009-05-01

    Full Text Available Microscopic chemical patterning of diamond surfaces by hydrogen and oxygen surface atoms is used for self-assembly of human osteoblastic cells into micro-arrays. The cell adhesion and assembly is further controlled by concentration of cells (2,500-10,000 cells/cm2and fetal bovine serum (0-15%. The cells are characterized by fluorescence microscopy of actin fibers and nuclei. The serum protein adsorption is studied by atomic force microscopy (AFM. The cells are arranged selectively on O-terminated patterns into 30-200 μm wide arrays. Higher cell concentrations allow colonization of unfavorable H-terminated regions due to mutual cell communication. There is no cell selectivity without the proteins in the medium. Based on the AFM, the proteins are present on both H- and O-terminated surfaces. Pronounced differences in their thickness, surface roughness, morphology, and phase imagesindicate different conformation of the proteins and explain the cell selectivity.

  1. Surface polarity of beta-HMX crystal and the related adhesive forces with Estane binder.

    Science.gov (United States)

    Yang, Lu

    2008-12-02

    Here I present the results on the study of surface properties of beta-HMX crystal utilizing molecular dynamics simulations. The surface polarity of three principal crystal surfaces, (011), (010), and (110), is investigated by measuring the water contact angles. The calculated contact angles are in excellent agreement with the values measured by experiment and show that the surface polarity of three crystal surfaces are different. The free energies and forces of detaching an Estane chain (with and without surrounding nitroplasticizer molecules) from the three principal crystal surfaces are also calculated using the umbrella sampling method. I find that the force for Estane detachment increases with the increasing HMX surface polarity. In addition, my results show that the nitroplasticizer also plays an important role in the adhesion between Estane and HMX surfaces.

  2. Engineered Surfaces for Mitigation of Insect Residue Adhesion

    Science.gov (United States)

    Siochi, Emilie J.; Smith, Joseph G.; Wohl, Christopher J.; Gardner, J. M.; Penner, Ronald K.; Connell, John W.

    2013-01-01

    Maintenance of laminar flow under operational flight conditions is being investigated under NASA s Environmentally Responsible Aviation (ERA) Program. Among the challenges with natural laminar flow is the accretion of residues from insect impacts incurred during takeoff or landing. Depending on air speed, temperature, and wing structure, the critical residue height for laminar flow disruption can be as low as 4 microns near the leading edge. In this study, engineered surfaces designed to minimize insect residue adhesion were examined. The coatings studied included chemical compositions containing functional groups typically associated with abhesive (non-stick) surfaces. To reduce surface contact by liquids and enhance abhesion, the engineered surfaces consisted of these coatings doped with particulate additives to generate random surface topography, as well as coatings applied to laser ablated surfaces having precision patterned topographies. Performance evaluation of these surfaces included contact angle goniometry of pristine coatings and profilometry of surfaces after insect impacts were incurred in laboratory scale tests, wind tunnel tests and flight tests. The results illustrate the complexity of designing antifouling surfaces for effective insect contamination mitigation under dynamic conditions and suggest that superhydrophobic surfaces may not be the most effective solution for preventing insect contamination on aircraft wing leading edges.

  3. Tuning the adhesion between polyimide substrate and MWCNTs/epoxy nanocomposite by surface treatment

    Science.gov (United States)

    Bouhamed, Ayda; Kia, Alireza Mohammadian; Naifar, Slim; Dzhagan, Volodymyr; Müller, Christian; Zahn, Dietrich R. T.; Choura, Slim; Kanoun, Olfa

    2017-11-01

    MWCNTs/epoxy nanocomposite thin films are coated on the polyimide (PI) flexible substrate, to be used as a strain sensor. Previous studies showed that the adhesion between polyimide and other materials are very poor. In this work, two approaches, oxygen plasma cleaning and simple solvent cleaning are performed for activation of the polyimide surface. In order to understand the impact of both cleaning techniques, the physicochemical properties of PI are measured and characterized using contact angle measurements (CAMs), X-ray photoelectron spectroscopy(XPS), and atomic force microscopy (AFM). In addition, the adhesion properties of PI/[MWCNTs/epoxy] systems by varying surface treatment time are investigated and evaluated using force-distance measurements by AFM. The results illustrate that the activated surface exhibits higher surface energy for oxygen plasma cleaning in comparison with the solvent cleaning method. The improvement can be related to the increase of oxygen concentration, which is accompanied by the enhancement of the polar component to 53.79 mN/m due to the formation of functional groups on the surface and the change of the substrate surface roughness from 1.72 nm to 15.5 nm. As a result, improved adhesion was observed from force-distance measurement between PI/[MWCNTs/epoxy] systems due to oxygen plasma effects.

  4. Fibroblast adhesion and activation onto micro-machined titanium surfaces.

    Science.gov (United States)

    Guillem-Marti, J; Delgado, L; Godoy-Gallardo, M; Pegueroles, M; Herrero, M; Gil, F J

    2013-07-01

    Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method. An array of titanium surfaces was obtained using a commercial computerized numerical control lathe, modifying the feed rate and the cutting depth. To elucidate the potential ability of the generated surfaces to activate connective tissue cells, a thorough gene (by real time - qPCR) and protein (by western blot or zymography) expression and cellular response characterization (cell morphology, cell adhesion and cell activation by secreting extracellular matrix (ECM) components and their enzyme regulators) was performed. Micro-grooved surfaces have statistically significant differences in the groove's width (approximately 10, 50 and 100 μm) depending on the applied advancing fixed speed. Field emission scanning electron microscopy images showed that fibroblasts oriented along the generated grooves, but they were only entirely accommodated on the wider grooves (≥50 μm). Micro-grooved surfaces exhibited an earlier cell attachment and activation, as seen by collagen Iα1 and fibronectin deposition and activation of ECM remodelling enzymes, compared with the other surfaces. However, fibroblasts could remain in an activated state on narrower surfaces (micro-grooved surfaces could improve implant integration at the gingival site with respect to polished surfaces. Micro-grooved surfaces enhance early fibroblast adhesion and activation, which could be critical for the formation of a biological seal and finally promote tissue integration. Surfaces with wider grooves (≥50 μm) seem to be more

  5. Evaluation of Encapsulant Adhesion to Surface Metallization of Photovoltaic Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Tracy, Jared; Dauskardt, Reinhold; Bosco, Nick

    2017-06-14

    Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of EVA encapsulant to screen printed silver metallization was evaluated. At room temperature, the fracture energy, Gc [J/m2], of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/AR coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 hours of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2, while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and elevated temperature, and may explain the propensity for delamination to occur at metallized surfaces in the field.

  6. Mercapto-based coupling agent for improved thermophotovoltaic device back surface reflector adhesion and reflectance

    Energy Technology Data Exchange (ETDEWEB)

    Wernsman, Bernard; Fiedor, Joseph N.; Irr, Lawrence G.; Palmisiano, Marc N.

    2016-10-04

    A back surface reflector (BSR) is described. The BSR includes a reflecting layer, a substrate and an adhesion layer between the reflecting layer and the substrate. The adhesion layer includes 3-mercaptopropyl (trimethoxy) silane (a.k.a. Merc).

  7. Improved adhesion at titanium surfaces via laser-induced surface oxidation and roughening

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, S. [Fraunhofer-Institut fuer Fertigungstechnik und Angewandte Materialforschung, Wiener Str. 12, 28359 Bremen (Germany); Institut fuer Mikro- und Nanotechnologien, Technische Universitaet Ilmenau, PF 100565, 98684 Ilmenau (Germany); Specht, U., E-mail: uwe.specht@ifam.fraunhofer.de [Fraunhofer-Institut fuer Fertigungstechnik und Angewandte Materialforschung, Wiener Str. 12, 28359 Bremen (Germany); Spiess, L.; Romanus, H.; Krischok, S.; Himmerlich, M. [Institut fuer Mikro- und Nanotechnologien, Technische Universitaet Ilmenau, PF 100565, 98684 Ilmenau (Germany); Ihde, J. [Fraunhofer-Institut fuer Fertigungstechnik und Angewandte Materialforschung, Wiener Str. 12, 28359 Bremen (Germany)

    2012-12-15

    Commercial titanium was treated in ambient atmosphere using pulsed Nd:YAG ({lambda}=1064nm) laser irradiation. Repeated laser treatments induce a removal of surface contaminants as well as the formation of a nanostructured top layer exhibiting a large effective surface and nanometer roughness. The laser induced oxidation leads to the presence of a surface layer with strongly improved, hydrothermally stable adhesion when joined to a one-component, hot-curing epoxy-based adhesive. Changes in the material properties have been characterized with respect to the topography, the chemical composition and the crystal structure using SEM, cross-beam FIB, XPS and XRD analyses in order to correlate the adhesion behavior with the structural and chemical characteristics of the surface.

  8. Effect of surface pattern on the adhesive friction of elastomers.

    Science.gov (United States)

    Wu-Bavouzet, Fanny; Cayer-Barrioz, Juliette; Le Bot, Alain; Brochard-Wyart, Françoise; Buguin, Axel

    2010-09-01

    We present experimental results for the friction of a flat surface against a hexagonally patterned surface, both being made of PolyDiMethylSiloxane. We simultaneously measure forces of range 10 mN and observe the contact under sliding velocities of about 100 μm/s. We observe adhesive friction on three different pattern heights (80, 310, and 2100 nm). Two kinds of contacts have been observed: the flat surface is in close contact with the patterned one (called intimate contact, observed for 80 nm) or only suspended on the tops on the asperities (called laid contact, observed for 2100 nm). In the range of velocities used, the contact during friction is similar to the static one. Furthermore, our experimental system presents a contact transition during friction for h=310 nm.

  9. Multi-functional surfaces with controllable wettability and water adhesion

    Science.gov (United States)

    Anastasiadis, Spiros H.; Frysali, Melani A.; Kenanakis, George; Kaklamani, Georgia; Papoutsakis, Lampros

    The design of multifunctional surfaces based on biomimetic structures has gained the interest of the scientific community. Novel multifunctional surfaces have been developed, able to alter their wetting properties in response to temperature and pH as well as light illumination, by combining proper chemistry and surface micro/nano-structuring using ultrafast (femtosecond) laser irradiation. The combination of the hierarchical surface with a ZnO and/or a responsive polymer coating results in efficient photo-active properties as well as reversible superhydrophobic / superhydrophilic surfaces in response to external stimuli. These surfaces can be optimized to exhibit high or zero water adhesion and/or controllable directionality as well. Moreover, they can be seeded with human fibroblasts to examine the cellular response on both surface roughness and surface chemistry. Acknowledgements: This research has been co-financed by the General Secretariat for Research and Technology (''ARISTEIA II'' Action, SMART-SURF) and the European Union (NFFA Europe -Grant agreement No. 654360).

  10. Surface functionalization of silicone rubber for permanent adhesion improvement.

    Science.gov (United States)

    Roth, Jan; Albrecht, Victoria; Nitschke, Mirko; Bellmann, Cornelia; Simon, Frank; Zschoche, Stefan; Michel, Stefan; Luhmann, Claudia; Grundke, Karina; Voit, Brigitte

    2008-11-04

    The surface properties of poly(dimethyl siloxane) (PDMS) layers screen printed onto silicon wafers were studied after oxygen and ammonia plasma treatments and subsequent grafting of poly(ethylene -alt-maleic anhydride) (PEMA) using X-ray photoelectron spectroscopy (XPS), roughness analysis, and contact angle and electrokinetic measurements. In the case of oxygen-plasma-treated PDMS, a hydrophilic, brittle, silica-like surface layer containing reactive silanol groups was obtained. These surfaces indicate a strong tendency for "hydrophobic recovery" due to the surface segregation of low-molecular-weight PDMS species. The ammonia plasma treatment of PDMS resulted in the generation of amino-functional surface groups and the formation of a weak boundary layer that could be washed off by polar liquids. To avoid the loss of the plasma modification effect and to achieve stabilization of the mechanically instable, functionalized PDMS top layer, PEMA was subsequently grafted directly or after using gamma-APS as a coupling agent on the plasma-activated PDMS surfaces. In this way, long-time stable surface functionalization of PDMS was obtained. The reactivity of the PEMA-coated PDMS surface caused by the availability of anhydride groups could be controlled by the number of amino functional surface groups of the PDMS surface necessary for the covalent binding of PEMA. The higher the number of amino functional surface groups available for the grafting-to procedure, the lower the hydrophilicity and hence the lower the reactivity of the PEMA-coated PDMS surface. Additionally, pull-off tests were applied to estimate the effect of surface modification on the adhesion between the silicone rubber and an epoxy resin.

  11. Low Ice Adhesion on Nano-Textured Superhydrophobic Surfaces under Supersaturated Conditions.

    Science.gov (United States)

    Bengaluru Subramanyam, Srinivas; Kondrashov, Vitaliy; Rühe, Jürgen; Varanasi, Kripa K

    2016-05-25

    Ice adhesion on superhydrophobic surfaces can significantly increase in humid environments because of frost nucleation within the textures. Here, we studied frost formation and ice adhesion on superhydrophobic surfaces with various surface morphologies using direct microscale imaging combined with macroscale adhesion tests. Whereas ice adhesion increases on microtextured surfaces, a 15-fold decrease is observed on nanotextured surfaces. This reduction is because of the inhibition of frost formation within the nanofeatures and the stabilization of vapor pockets. Such "Cassie ice"-promoting textures can be used in the design of anti-icing surfaces.

  12. Effects of surface roughness and dimorphism on the adhesion of Candida albicans to the surface of resins: scanning electron microscope analyses of mode and number of adhesions.

    Science.gov (United States)

    Mayahara, Mitsuori; Kataoka, Ryuta; Arimoto, Takafumi; Tamaki, Yukimichi; Yamaguchi, Nobuaki; Watanabe, Yuki; Yamasaki, Yoshizumi; Miyazaki, Takashi

    2014-11-01

    Candida albicans is a common oral fungus but can cause serious conditions such as Candida stomatitis. We investigated C. albicans adhesion to the surface of denture-base resins at two growth phases. Fungal suspensions of logarithmic (9 h) and stationary phase (24 h) C. albicans (JCM2085) were used. Scanning electron microscopy (SEM) confirmed that yeast and mycelial forms were predominant in 9-h and 24-h cultures, respectively. Resin strips were polished to three surface roughness levels (Ra 3.2 μm, Ra 0.48 μm and Ra 0.06 μm) and were then immersed in C. albicans suspensions for both phases. The SEM images were taken at five sites on each strip. Adhesion of mycelial-form C. albicans on rough surfaces (Ra = 3.2) was 2.2 times higher than on smooth surfaces (Ra = 0.06; 7030 vs 3580 adhesions/mm(2), P < 0.01). The hyphae of these mycelial forms fully penetrated the surface cracks. Fewer adhesions occurred for yeast-form C. albicans, regardless of surface type (440-620 adhesions/mm(2), P = n.s.). Adhesion of yeast-form C. albicans was indifferent to surface roughness. In contrast, mycelial adhesion increased with surface roughness of the resin because mycelia infiltrated the minute protuberances on rough surfaces. © 2013 Wiley Publishing Asia Pty Ltd.

  13. Effects of Surface Treatments on Nylon 6,6 via Non-thermal Atmospheric Plasma for Thermoplastic Adhesives

    Science.gov (United States)

    Wu, Chi-Chin; Bujanda, Andres; Demaree, John; Robinette, Jason; Weerasooriya, Amanda; Flanagan, David; ARL Plasma Group, CCEP, WMRD Team

    2015-03-01

    This work aims to modify the properties of Nylon 6,6 surfaces for attaining improved interfacial adhesion to thermoplastic composites utilizing atmospheric non-thermal plasma treatments followed by silane treatments using 3-aminopropyltriethoxysilane (APS) in some cases. An L-shaped dielectric barrier discharge configuration was employed to expose nylon substrates to oxygen-containing gas plasmas such as He/O2 and He/H2O, respectively, at room temperature. The chemically-modified surface of the substrate after plasma exposure was immediately examined by static water contact angle wettability measurements and X-ray photoelectron spectroscopy. It was found that the surface hydrophilicity was substantially enhanced and the amount of surface oxygen was significantly increased after a three-minute plasma exposure due to the increased surface energy and additional O-H bonds. The enhancements on interfacial adhesion were evaluated with lap shear tests using three types of adhesives: EPON 825/D230, EPON 825/D2000 and sikaflex252, respectively. The results of tensile tests on the adhesive joints showed an almost ~ 300% increase in interfacial adhesive strength for EPON 825/D230 bonds after plasma treatments. Finite element modeling of adhesive joints for bond strength is underway to compare with experimental results and study the quantitative relations between the mechanical properties within the bond and at interfaces.

  14. Cell adhesion on Ti surface with controlled roughness

    Energy Technology Data Exchange (ETDEWEB)

    Burgos-Asperilla, L.; Garcia-Alonso, M. C.; Escudero, M. L.; Alonso, C.

    2015-07-01

    In this report, the in situ interaction between Saos-2 osteoblast cells and a smooth Ti surface was examined over time. The adhesion kinetics and mechanisms of cellular proliferation were monitored by quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). The rate of Saos-2 attachment on Ti surfaces, obtained from the measurements performed with the QCM, is a first-order reaction, with k=2.10{sup -}3 min{sup -}1. The impedance measurements indicate that in the absence of cells, the Ti resistance diminishes over time (7 days), due to the presence of amino acids and proteins from the culture medium that have been adsorbed, while in the presence of osteoblasts, this decrease is much greater because of the compounds generated by the cells that accelerate the dissolution of Ti. (Author)

  15. Temperature-Induced Switchable Adhesion using Nickel-Titanium-Polydimethylsiloxane Hybrid Surfaces.

    Science.gov (United States)

    Frensemeier, Mareike; Kaiser, Jessica S; Frick, Carl P; Schneider, Andreas S; Arzt, Eduard; Fertig, Ray S; Kroner, Elmar

    2015-05-01

    A switchable dry adhesive based on a nickel-titanium (NiTi) shape-memory alloy with an adhesive silicone rubber surface has been developed. Although several studies investigate micropatterned, bioinspired adhesive surfaces, very few focus on reversible adhesion. The system here is based on the indentation-induced two-way shape-memory effect in NiTi alloys. NiTi is trained by mechanical deformation through indentation and grinding to elicit a temperature-induced switchable topography with protrusions at high temperature and a flat surface at low temperature. The trained surfaces are coated with either a smooth or a patterned adhesive polydimethylsiloxane (PDMS) layer, resulting in a temperature-induced switchable surface, used for dry adhesion. Adhesion tests show that the temperature-induced topographical change of the NiTi influences the adhesive performance of the hybrid system. For samples with a smooth PDMS layer the transition from flat to structured state reduces adhesion by 56%, and for samples with a micropatterned PDMS layer adhesion is switchable by nearly 100%. Both hybrid systems reveal strong reversibility related to the NiTi martensitic phase transformation, allowing repeated switching between an adhesive and a nonadhesive state. These effects have been discussed in terms of reversible changes in contact area and varying tilt angles of the pillars with respect to the substrate surface.

  16. Adhesion of Aeromonas hydrophila to Glass Surfaces Modified with Organosilanes

    Directory of Open Access Journals (Sweden)

    Dorota Kregiel

    2013-01-01

    Full Text Available The aim of this research is to study the adhesive properties of Aeromonas hydrophila to glass surfaces modified using four silanes with different reactive groups, namely (3-glycidoxypropyl diethoxysilane, (3-N,N-dimethyl-3-N-n hexadecylammoniopropyltrimethoxysilane chloride, (3-N,N,N-triethanolammoniopropyltrimethoxysilane chloride, and (3-N,N-dimethyl- 3-N-n-octylammoniopropyltrimethoxysilane chloride. The strain used in the study was A. hydrophila LOCK0968, isolated from the unchlorinated communal water distribution system in Poland. The effect of glass modification after chemical treatment was analyzed using surface tension measurement. The adhesive properties of the bacteria were studied in a water environment with a low concentration of organic compounds, using luminometric and microscopic methods. Additionally, the viability of the adherent bacterial cells was evaluated by counting the colony-forming units. The presence of active compounds in the culture medium after incubation with a modified carrier was verified using the Kirby- -Bauer method. Half of the chemically modified glass surfaces exhibited better characteristics in comparison with native glass. Among the examined modifying agents, (3-N,N,N-triethanolammoniopropyl trimethoxysilane chloride and (3-N,N-dimethyl-3-N-n octylammoniopropyl trimethoxysilane chloride showed the best antiadhesive and antibacterial properties. The most effective glass modification, with (3-N,N,N triethanolammoniopropyltrimethoxysilane chloride, was able to reduce the bacterial cell count by more than three orders of magnitude. The carriers had no significant effect on the viability of the free bacterial cells in the culture medium. Therefore, it can be said that the modified glass surface alone accounts for the antibacterial activity of the active organosilanes.

  17. Self-Cleaning Synthetic Adhesive Surfaces Mimicking Tokay Geckos.

    Energy Technology Data Exchange (ETDEWEB)

    Branson, Eric D.; Singh, Seema; Burckel, David Bruce; Fan, Hongyou; Houston, Jack E.; Brinker, C. Jeffrey; Johnson, Patrick

    2006-11-01

    A gecko's extraordinary ability to suspend itself from walls and ceilings of varied surface roughness has interested humans for hundreds of years. Many theories and possible explanations describing this phenomenon have been proposed including sticky secretions, microsuckers, and electrostatic forces; however, today it is widely accepted that van der Waals forces play the most important role in this type of dry adhesion. Inarguably, the vital feature that allows a gecko's suspension is the presence of billions 3 of tiny hairs on the pad of its foot called spatula. These features are small enough to reach within van der Waals distances of any surface (spatula radius %7E100 nm); thus, the combined effect of billions of van der Waals interactions is more than sufficient to hold a gecko's weight to surfaces such as smooth ceilings or wet glass. Two lithographic approaches were used to make hierarchal structures with dimensions similar to the gecko foot dimensions noted above. One approach combined photo-lithography with soft lithography (micro-molding). In this fabrication scheme the fiber feature size, defined by the alumina micromold was 0.2 um in diameter and 60 um in height. The second approach followed more conventional photolithography-based patterning. Patterned features with dimensions %7E0.3 mm in diameter by 0.5 mm tall were produced. We used interfacial force microscopy employing a parabolic diamond tip with a diameter of 200 nm to measure the surface adhesion of these structures. The measured adhesive forces ranged from 0.3 uN - 0.6 uN, yielding an average bonding stress between 50 N/cm2 to 100 N/cm2. By comparison the reported literature value for the average stress of a Tokay gecko foot is 10 N/cm2. Acknowledgements This work was funded by Sandia National Laboratory's Laboratory Directed Research & Development program (LDRD). All coating processes were conducted in the cleanroom facility located at the University of New Mexico

  18. SCANNING ELECTRON-MICROSCOPIC EVALUATION OF THE FRACTURED SURFACES OF CANINE CALCULI FROM SUBSTRATA WITH DIFFERENT SURFACE FREE-ENERGY

    NARCIS (Netherlands)

    UYEN, HMW; JONGEBLOED, WL; BUSSCHER, HJ

    1991-01-01

    The strength of adhesion between dental calculus and enamel or dentin surfaces determines the ease with which the calculus can be removed by brushing or professional dental treatment. In this study, we examined the adhesion of canine calculi formed on substrata with different surface free energies

  19. Enterococcus faecalis surface proteins determine its adhesion mechanism to bile drain materials

    NARCIS (Netherlands)

    Waar, K; van der Mei, HC; Harmsen, HJM; Degener, JE; Busscher, HJ

    An important step in infections associated with biliary drains is adhesion of micro-organisms to the surface. In this study the role of three surface proteins of Enterococcus faecalis (enterococcal surface protein, aggregation substances 1 and 373) in the adhesion to silicone rubber,

  20. Functional adhesive surfaces with “gecko” effect: the concept of contact splitting

    NARCIS (Netherlands)

    Kamperman, M.M.G.; Kroner, E.; Campo, del A.; McMeeking, R.M.; Arzt, E.

    2010-01-01

    Nature has developed reversibly adhesive surfaces whose stickiness has attracted much research attention over the last decade. The central lesson from nature is that “patterned” or “fibrillar” surfaces can produce higher adhesion forces to flat and rough substrates than smooth surfaces. This paper

  1. Superhydrophobic surfaces fabricated by femtosecond laser with tunable water adhesion: from lotus leaf to rose petal.

    Science.gov (United States)

    Long, Jiangyou; Fan, Peixun; Gong, Dingwei; Jiang, Dafa; Zhang, Hongjun; Li, Lin; Zhong, Minlin

    2015-05-13

    Superhydrophobic surfaces with tunable water adhesion have attracted much interest in fundamental research and practical applications. In this paper, we used a simple method to fabricate superhydrophobic surfaces with tunable water adhesion. Periodic microstructures with different topographies were fabricated on copper surface via femtosecond (fs) laser irradiation. The topography of these microstructures can be controlled by simply changing the scanning speed of the laser beam. After surface chemical modification, these as-prepared surfaces showed superhydrophobicity combined with different adhesion to water. Surfaces with deep microstructures showed self-cleaning properties with extremely low water adhesion, and the water adhesion increased when the surface microstructures became flat. The changes in surface water adhesion are attributed to the transition from Cassie state to Wenzel state. We also demonstrated that these superhydrophobic surfaces with different adhesion can be used for transferring small water droplets without any loss. We demonstrate that our approach provides a novel but simple way to tune the surface adhesion of superhydrophobic metallic surfaces for good potential applications in related areas.

  2. Effects of surface treatment of aluminium alloy 1050 on the adhesion and anticorrosion properties of the epoxy coating

    Energy Technology Data Exchange (ETDEWEB)

    Sharifi Golru, S., E-mail: samanesharifi@aut.ac.ir [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, P.O. Box 15875-4413 Tehran (Iran, Islamic Republic of); Attar, M.M., E-mail: attar@aut.ac.ir [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, P.O. Box 15875-4413 Tehran (Iran, Islamic Republic of); Ramezanzadeh, B. [Department of Surface Coating and Corrosion, Institute for Color Science and Technology, No. 59,Vafamanesh St, Hosainabad Sq, Lavizan, Tehran (Iran, Islamic Republic of)

    2015-08-01

    Highlights: • Aluminium alloy 1050 was treated by zirconium-based (Zr) conversion coating. • The surface morphology and surface free energy of the samples were obtained. • The adhesion properties of the epoxy coating was studied on the treated samples. • The corrosion resistance of the epoxy coating was enhanced on treated samples. - Abstract: The objective of this work is to investigate the effects of zirconium-based (Zr) conversion coating on the adhesion properties and corrosion resistance of an epoxy/polyamide coating applied on the aluminium alloy 1050 (AA1050). Field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectrum (EDS), atomic force microscope (AFM) and contact angle measuring device were employed in order to characterize the surface characteristics of the Zr treated AA1050 samples. The epoxy/polyamide coating was applied on the untreated and Zr treated samples. The epoxy coating adhesion to the aluminium substrate was evaluated by pull-off test before and after 30 days immersion in 3.5% w/w NaCl solution. In addition, the electrochemical impedance spectroscopy (EIS) and salt spray tests were employed to characterize the corrosion protection properties of the epoxy coating applied on the AA1050 samples. Results revealed that the surface treatment of AA1050 by zirconium conversion coating resulted in the increase of surface free energy and surface roughness. The dry and recovery (adhesion strength after 30 days immersion in the 3.5 wt% NaCl solution) adhesion strengths of the coatings applied on the Zr treated aluminium samples were greater than untreated sample. In addition, the adhesion loss of the coating applied on the Zr treated aluminium substrate was lower than other samples. Also, the results obtained from EIS and salt spray test clearly revealed that the Zr conversion coating could enhance the corrosion protective performance of the epoxy coating significantly.

  3. Effects of surface treatment of aluminium alloy 1050 on the adhesion and anticorrosion properties of the epoxy coating

    International Nuclear Information System (INIS)

    Sharifi Golru, S.; Attar, M.M.; Ramezanzadeh, B.

    2015-01-01

    Highlights: • Aluminium alloy 1050 was treated by zirconium-based (Zr) conversion coating. • The surface morphology and surface free energy of the samples were obtained. • The adhesion properties of the epoxy coating was studied on the treated samples. • The corrosion resistance of the epoxy coating was enhanced on treated samples. - Abstract: The objective of this work is to investigate the effects of zirconium-based (Zr) conversion coating on the adhesion properties and corrosion resistance of an epoxy/polyamide coating applied on the aluminium alloy 1050 (AA1050). Field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectrum (EDS), atomic force microscope (AFM) and contact angle measuring device were employed in order to characterize the surface characteristics of the Zr treated AA1050 samples. The epoxy/polyamide coating was applied on the untreated and Zr treated samples. The epoxy coating adhesion to the aluminium substrate was evaluated by pull-off test before and after 30 days immersion in 3.5% w/w NaCl solution. In addition, the electrochemical impedance spectroscopy (EIS) and salt spray tests were employed to characterize the corrosion protection properties of the epoxy coating applied on the AA1050 samples. Results revealed that the surface treatment of AA1050 by zirconium conversion coating resulted in the increase of surface free energy and surface roughness. The dry and recovery (adhesion strength after 30 days immersion in the 3.5 wt% NaCl solution) adhesion strengths of the coatings applied on the Zr treated aluminium samples were greater than untreated sample. In addition, the adhesion loss of the coating applied on the Zr treated aluminium substrate was lower than other samples. Also, the results obtained from EIS and salt spray test clearly revealed that the Zr conversion coating could enhance the corrosion protective performance of the epoxy coating significantly

  4. Modeling and experiments of the adhesion force distribution between particles and a surface.

    Science.gov (United States)

    You, Siming; Wan, Man Pun

    2014-06-17

    Due to the existence of surface roughness in real surfaces, the adhesion force between particles and the surface where the particles are deposited exhibits certain statistical distributions. Despite the importance of adhesion force distribution in a variety of applications, the current understanding of modeling adhesion force distribution is still limited. In this work, an adhesion force distribution model based on integrating the root-mean-square (RMS) roughness distribution (i.e., the variation of RMS roughness on the surface in terms of location) into recently proposed mean adhesion force models was proposed. The integration was accomplished by statistical analysis and Monte Carlo simulation. A series of centrifuge experiments were conducted to measure the adhesion force distributions between polystyrene particles (146.1 ± 1.99 μm) and various substrates (stainless steel, aluminum and plastic, respectively). The proposed model was validated against the measured adhesion force distributions from this work and another previous study. Based on the proposed model, the effect of RMS roughness distribution on the adhesion force distribution of particles on a rough surface was explored, showing that both the median and standard deviation of adhesion force distribution could be affected by the RMS roughness distribution. The proposed model could predict both van der Waals force and capillary force distributions and consider the multiscale roughness feature, greatly extending the current capability of adhesion force distribution prediction.

  5. Tuning cell adhesion on polymeric and nanocomposite surfaces: Role of topography versus superhydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Zangi, Sepideh [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Hejazi, Iman [Department of Polymer Engineering & Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Seyfi, Javad, E-mail: Jseyfi@gmail.com [Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, P.O. Box 36155-163, Shahrood (Iran, Islamic Republic of); Hejazi, Ehsan [Department of Clinical Nutrition and Dietetics, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran (Iran, Islamic Republic of); Khonakdar, Hossein Ali [Department of Polymer Engineering, Faculty of Engineering, South Tehran Branch, Islamic Azad University, P.O. Box 19585-466, Tehran (Iran, Islamic Republic of); Davachi, Seyed Mohammad [School of Chemical Engineering, University of Tehran, P.O. Box 11155-4563, Tehran (Iran, Islamic Republic of)

    2016-06-01

    Development of surface modification procedures which allow tuning the cell adhesion on the surface of biomaterials and devices is of great importance. In this study, the effects of different topographies and wettabilities on cell adhesion behavior of polymeric surfaces are investigated. To this end, an improved phase separation method was proposed to impart various wettabilities (hydrophobic and superhydrophobic) on polypropylene surfaces. Surface morphologies and compositions were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. Cell culture was conducted to evaluate the adhesion of 4T1 mouse mammary tumor cells. It was found that processing conditions such as drying temperature is highly influential in cell adhesion behavior due to the formation of an utterly different surface topography. It was concluded that surface topography plays a more significant role in cell adhesion behavior rather than superhydrophobicity since the nano-scale topography highly inhibited the cell adhesion as compared to the micro-scale topography. Such cell repellent behavior could be very useful in many biomedical devices such as those in drug delivery and blood contacting applications as well as biosensors. - Highlights: • A novel method is presented for fabrication of superhydrophobic surfaces. • The presence of nanoparticles in non-solvent bath notably promoted phase separation. • Topography had a more notable impact on cell adhesion than superhydrophobicity. • Nano-scale topographical features highly impeded cell adhesion on polymer surfaces.

  6. Laser surface treatment for enhanced titanium to carbon fiber-reinforced polymer adhesion

    NARCIS (Netherlands)

    Palavra, Armin; Coelho, Bruno N.; de Hosson, Jeff Th. M.; Lima, Milton S. F.; Carvalho, Sheila M.; Costa, Adilson R.

    The adhesion between carbon fiber-reinforced polymer (CFRP) and titanium parts can be improved by laser surface texturing before gluing them together. Here, a pulsed Nd:YAG laser was employed before bonding of the textured surfaces using an epoxy paste adhesive. To investigate the influence of the

  7. Influence of surface roughness on streptococcal adhesion forces to composite resins

    NARCIS (Netherlands)

    Mei, Li; Busscher, Henk J; van der Mei, Henny C; Ren, Yijin

    OBJECTIVE: To determine streptococcal adhesion forces with composite resins with different surface roughness. METHODS: Polishing and grinding were applied to obtain smooth (roughness 20 nm), moderately rough (150 nm) and rough (350 nm) surfaces of two orthodontic, light-cured composites. Adhesion

  8. Effect of nano- and micro-roughness on adhesion of bioinspired micropatterned surfaces

    NARCIS (Netherlands)

    Canas, N.; Kamperman, M.M.G.; Volker, B.; Kroner, E.; McMeeking, R.M.; Arzt, E.

    2012-01-01

    In this work, the adhesion of biomimetic polydimethylsiloxane (PDMS) pillar arrays with mushroom-shaped tips was studied on nano- and micro-rough surfaces and compared to unpatterned controls. The adhesion strength on nano-rough surfaces invariably decreased with increasing roughness, but pillar

  9. Focal Adhesion of Osteoblastic Cells on Titanium Surface with Amine Functionalities Formed by Plasma Polymerization

    Science.gov (United States)

    Song, Heesang; Jung, Sang Chul; Kim, Byung Hoon

    2012-08-01

    To enhance the focal adhesion of osteoblastic cells on a titanium surface, plasma polymerized allyl amine (AAm) thin films were deposited by plasma polymerization. This plasma polymer functionalization of titanium is advantageous for osteoblastic focal adhesion formation. Such Ti surfaces are useful for the fabrication of titanium-based dental implants for enhancement of osseointegration.

  10. Friction and adhesion of gecko-inspired PDMS flaps on rough surfaces.

    Science.gov (United States)

    Yu, Jing; Chary, Sathya; Das, Saurabh; Tamelier, John; Turner, Kimberly L; Israelachvili, Jacob N

    2012-08-07

    Geckos have developed a unique hierarchical structure to maintain climbing ability on surfaces with different roughness, one of the extremely important parameters that affect the friction and adhesion forces between two surfaces. Although much attention has been paid on fabricating various structures that mimic the hierarchical structure of a gecko foot, yet no systematic effort, in experiment or theory, has been made to quantify the effect of surface roughness on the performance of the fabricated structures that mimic the hierarchical structure of geckos. Using a modified surface forces apparatus (SFA), we measured the adhesion and friction forces between microfabricated tilted PDMS flaps and optically smooth SiO(2) and rough SiO(2) surfaces created by plasma etching. Anisotropic adhesion and friction forces were measured when sliding the top glass surface along (+y) and against (-y) the tilted direction of the flaps. Increasing the surface roughness first increased the adhesion and friction forces measured between the flaps and the rough surface due to topological matching of the two surfaces but then led to a rapid decrease in both of these forces. Our results demonstrate that the surface roughness significantly affects the performance of gecko mimetic adhesives and that different surface textures can either increase or decrease the adhesion and friction forces of the fabricated adhesives.

  11. The Role of Surface Chemistry in Adhesion and Wetting of Gecko Toe Pads

    Science.gov (United States)

    Badge, Ila; Stark, Alyssa Y.; Paoloni, Eva L.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2014-10-01

    An array of micron-sized setal hairs offers geckos a unique ability to walk on vertical surfaces using van der Waals interactions. Although many studies have focused on the role of surface morphology of the hairs, very little is known about the role of surface chemistry on wetting and adhesion. We expect that both surface chemistry and morphology are important, not only to achieve optimum dry adhesion but also for increased efficiency in self-cleaning of water and adhesion under wet conditions. Here, we used a plasma-based vapor deposition process to coat the hairy patterns on gecko toe pad sheds with polar and non-polar coatings without significantly perturbing the setal morphology. By a comparison of wetting across treatments, we show that the intrinsic surface of gecko setae has a water contact angle between 70-90°. As expected, under wet conditions, adhesion on a hydrophilic surface (glass) was lower than that on a hydrophobic surface (alkyl-silane monolayer on glass). Surprisingly under wet and dry conditions the adhesion was comparable on the hydrophobic surface, independent of the surface chemistry of the setal hairs. This work highlights the need to utilize morphology and surface chemistry in developing successful synthetic adhesives with desirable adhesion and self-cleaning properties.

  12. Effect of sizing on carbon fiber surface properties and fibers/epoxy interfacial adhesion

    International Nuclear Information System (INIS)

    Dai Zhishuang; Shi Fenghui; Zhang Baoyan; Li Min; Zhang Zuoguang

    2011-01-01

    This paper aims to study effect of sizing on surface properties of carbon fiber and the fiber/epoxy interfacial adhesion by comparing sized and desized T300B and T700SC carbon fibers. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the desized carbon fibers present less concentration of activated carbon, especially those connect with the hydroxyl and epoxy groups. Inverse gas chromatography (IGC) analysis reveals that the desized carbon fibers have larger dispersive surface energy γ S D and smaller polar component γ S SP than the commercial sized ones. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the desized carbon fiber/epoxy is higher than those of the T300B and T700SC. Variations of the IFSS for both the sized and desized carbon fibers correspond to γ S D /γ S tendency of the fiber surface, however the work of adhesion does not reveal close correlation with IFSS trend for different fiber/epoxy systems.

  13. Improved adhesion of superhydrophobic layer on metal surfaces via one step spraying method

    Directory of Open Access Journals (Sweden)

    Wael I. El Dessouky

    2017-03-01

    Full Text Available Superhydrophobic metal substrates have been fabricated by a simple spraying method. The processes of decreasing surface free energy and increasing surface roughness have been accomplished in one step via the addition of functionalized silica (silica nano particles with octyltriethoxysilane to adhesive polymer. The method is simple, cost-effective and can be applied on the large industrial scale. Scanning electron microscopy (SEM was used for surface morphology analysis, showing the roughness produced by surface treatment. The wettability of the micro-nano silica film varied from hydrophilicity (water contact angle 88° to superhydrophobicity (water contact angle 156.9°, while sliding contact angles dramatically decreased (<5° by adding Functionalized silica and/or adhesive polymer. Roughness increased with silica increment which improves the wettability. The coatings were electrochemically characterized by electrochemical impedance spectroscopy (EIS and Tafel polarization curves; it was found that both systems had good performance against corrosion in 3.5% sodium chloride solution. Furthermore, the stability of the coated layer on copper substrate was investigated.

  14. Surface Meteorology and Solar Energy

    Data.gov (United States)

    National Aeronautics and Space Administration — Surface Meteorology and Solar Energy data - over 200 satellite-derived meteorology and solar energy parameters, monthly averaged from 22 years of data, global solar...

  15. Surface tension driven shaping of adhesive microfluidic channel walls

    DEFF Research Database (Denmark)

    Janting, Jakob; Storm, Elisabeth K.; Geschke, Oliver

    2005-01-01

    , line height and distance, and temperature. Focus of the work has been on predicting the equilibrium geometries with FEM simulations using as input measured adhesive wetting angles, different adhesive line distances and height. The studied substrates are glass microscope slides, PEEK and PMMA...

  16. Influence of surface features on the adhesion of Staphyloccocus epidermidis to Ag–TiCN thin films

    International Nuclear Information System (INIS)

    Carvalho, Isabel; Almeida Alves, Cristiana Filipa; Carvalho, Sandra; Henriques, Mariana; Oliveira, João Carlos; Piedade, Ana Paula

    2013-01-01

    Staphylococcus epidermidis has emerged as one of the major nosocomial pathogens associated with infections of implanted medical devices. The initial adhesion of these organisms to the surface of biomaterials is assumed to be an important stage in their colonization. The main objective of this work is to assess the influence of surface features on the adhesion of S. epidermidis to Ag–TiCN coatings deposited by dc reactive magnetron sputtering. The structural results obtained by x-ray diffraction show that the coatings crystallize in a B1-NaCl crystal structure typical of TiC 0.3 N 0.7 . The increase of Ag content promoted the formation of Ag crystalline phases. According to the results obtained with atomic force microscopy, a decrease on the surface roughness of the films from 39 to 7 nm is observed as the Ag content increases from 0 to 15 at.%. Surface energy results show that the increase of Ag promotes an increase in hydrophobicity. Bacterial adhesion and biofilm formation on coatings were assessed by the enumeration of the number of viable cells. The results showed that the surface with lower roughness and higher hydrophobicity leads to greater bacterial adhesion and biofilm formation, highlighting that surface morphology and hydrophobicity rule the colonization of materials. (paper)

  17. Adhesion, Proliferation and Migration of NIH/3T3 Cells on Modified Polyaniline Surfaces.

    Science.gov (United States)

    Rejmontová, Petra; Capáková, Zdenka; Mikušová, Nikola; Maráková, Nela; Kašpárková, Věra; Lehocký, Marián; Humpolíček, Petr

    2016-09-15

    Polyaniline shows great potential and promises wide application in the biomedical field thanks to its intrinsic conductivity and material properties, which closely resemble natural tissues. Surface properties are crucial, as these predetermine any interaction with biological fluids, proteins and cells. An advantage of polyaniline is the simple modification of its surface, e.g., by using various dopant acids. An investigation was made into the adhesion, proliferation and migration of mouse embryonic fibroblasts on pristine polyaniline films and films doped with sulfamic and phosphotungstic acids. In addition, polyaniline films supplemented with poly (2-acrylamido-2-methyl-1-propanesulfonic) acid at various ratios were tested. Results showed that the NIH/3T3 cell line was able to adhere, proliferate and migrate on the pristine polyaniline films as well as those films doped with sulfamic and phosphotungstic acids; thus, utilization of said forms in biomedicine appears promising. Nevertheless, incorporating poly (2-acrylamido-2-methyl-1-propanesulfonic) acid altered the surface properties of the polyaniline films and significantly affected cell behavior. In order to reveal the crucial factor influencing the surface/cell interaction, cell behavior is discussed in the context of the surface energy of individual samples. It was clearly demonstrated that the lesser the difference between the surface energy of the sample and cell, the more cyto-compatible the surface is.

  18. Effects of contact cap dimension on dry adhesion of bioinspired mushroom-shaped surfaces

    Science.gov (United States)

    Wang, Yue; Shao, Jinyou; Ding, Yucheng; Li, Xiangming; Tian, Hongmiao; Hu, Hong

    2015-03-01

    Dry adhesion observed in small creatures, such as spiders, insects, and geckos, has many great advantages such as repeatability and strong adhesiveness. In order to mimic these unique performances, fibrillar surface with a mushroom shaped end has drawn lots of attentions because of its advantage in efficiently enhancing adhesion compared with other sphere or simple flat ends. Here, in order to study the effects of contact cap dimension on adhesion strength, patterned surfaces of mushroom-shaped micropillars with differing cap diameters are fabricated based on the conventional photolithography and molding. The normal adhesion strength of these dry adhesives with varying cap diameters is measured with home-built equipment. The strength increases with the rise of cap diameter, and interestingly it becomes strongest when the mushroom caps join together.

  19. Role of Surface Chemistry in Grain Adhesion and Dissipation during Collisions of Silica Nanograins

    Energy Technology Data Exchange (ETDEWEB)

    Quadery, Abrar H.; Tucker, William C.; Dove, Adrienne R.; Schelling, Patrick K. [Department of Physics, University of Central Florida, Orlando, FL 32816-2385 (United States); Doan, Baochi D., E-mail: patrick.schelling@ucf.edu [Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816-2385 (United States)

    2017-08-01

    The accretion of dust grains to form larger objects, including planetesimals, is a central problem in planetary science. It is generally thought that weak van der Waals interactions play a role in accretion at small scales where gravitational attraction is negligible. However, it is likely that in many instances, chemical reactions also play an important role, and the particular chemical environment on the surface could determine the outcomes of dust grain collisions. Using atomic-scale simulations of collisional aggregation of nanometer-sized silica (SiO{sub 2}) grains, we demonstrate that surface hydroxylation can act to weaken adhesive forces and reduce the ability of mineral grains to dissipate kinetic energy during collisions. The results suggest that surface passivation of dangling bonds, which generally is quite complete in an Earth environment, should tend to render mineral grains less likely to adhere during collisions. It is shown that during collisions, interactions scale with interparticle distance in a manner consistent with the formation of strong chemical bonds. Finally, it is demonstrated that in the case of collisions of nanometer-scale grains with no angular momentum, adhesion can occur even for relative velocities of several kilometers per second. These results have significant implications for early planet formation processes, potentially expanding the range of collision velocities over which larger dust grains can form.

  20. Effects of trimethylsilane plasma coating on the hydrophobicity of denture base resin and adhesion of Candida albicans on resin surfaces.

    Science.gov (United States)

    Liu, Tianshuang; Xu, Changqi; Hong, Liang; Garcia-Godoy, Franklin; Hottel, Timothy; Babu, Jegdish; Yu, Qingsong

    2017-12-01

    Candida-associated denture stomatitis is the most common oral mucosal lesion among denture wearers. Trimethylsilane (TMS) plasma coating may inhibit the growth of Candida albicans on denture surfaces. The purpose of this in vitro study was to investigate whether TMS plasma coatings can effectively reduce C albicans adhesion on denture base acrylic resin surfaces. Sixty denture base acrylic resin disks with smooth and rough surfaces were prepared and were either left untreated (control group) or coated with TMS monomer (experimental group) by using plasma. Contact angles were measured immediately after TMS plasma coating. The morphology of C albicans adhesion was observed with scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) was used to characterize the elemental composition of the specimen surface. An adhesion test was performed by incubating the resin disk specimens in C albicans suspensions (1×10 7 cells/mL) at 37°C for 24 hours and further measuring the optical density of the C albicans by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay test. One-way ANOVA and 2-way ANOVA were followed by a post hoc test analysis (α=.05). The group with TMS coating exhibited a more hydrophobic surface than the control group. EDS analysis revealed successful TMS plasma coating. The difference in the mean contact angles between the uncoated group and the TMS-coated group was statistically significant (Pcoating than on the surfaces of the experimental group. In the adhesion test, the amount of C albicans adhering to the surface of denture base resin with the TMS coating was significantly less than that on the surfaces without TMS coating (Pcoating significantly reduced the adhesion of C albicans to the denture base resin and may reduce denture stomatitis. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Laser Surface Preparation for Adhesive Bonding of Ti-6Al-4V

    Science.gov (United States)

    Belcher, Marcus A.; List, Martina S.; Wohl, Christopher J.; Ghose, Sayata; Watson, Kent A.; Hopkins, John W.; Connell, John W.

    2010-01-01

    Adhesively bonded structures are potentially lighter in weight than mechanically fastened ones, but existing surface treatments are often considered unreliable. Two main problems in achieving reproducible and durable adhesive bonds are surface contamination and variability in standard surface preparation techniques. In this work three surface pretreatments were compared: laser etching with and without grit blasting and conventional Pasa-Jell treatment. Ti-6Al-4V surfaces were characterized by contact angle goniometry, optical microscopy, and X-ray photoelectron spectroscopy (XPS). Laser -etching was found to produce clean surfaces with precisely controlled surface topographies and PETI-5 lap shear strengths and durabilities were equivalent to those produced with Pasa-Jell.

  2. Surface Modification of Titanium and Polyimide Sheet for Adhesive Bonding

    NARCIS (Netherlands)

    Akram, M.

    2015-01-01

    Major industrial sectors like automotive, aerospace and others are increasingly using polymer composites in their structural parts. Polyimide sheet and adhesives, are high performance polymers. They are widely used in various engineering applications due to their excellent thermal, mechanical and

  3. Investigating the effects of membrane deformability on artificial capsule adhesion to the functionalized surface.

    Science.gov (United States)

    Balsara, Hiren D; Banton, Rohan J; Eggleton, Charles D

    2016-10-01

    Understanding, manipulating and controlling cellular adhesion processes can be critical in developing biomedical technologies. Adhesive mechanisms can be used to the target, pattern and separate cells such as leukocytes from whole blood for biomedical applications. The deformability response of the cell directly affects the rolling and adhesion behavior under viscous linear shear flow conditions. To that end, the primary objective of the present study was to investigate numerically the influence of capsule membrane's nonlinear material behavior (i.e. elastic-plastic to strain hardening) on the rolling and adhesion behavior of representative artificial capsules. Specifically, spherical capsules with radius of [Formula: see text] were represented using an elastic membrane governed by a Mooney-Rivlin strain energy functions. The surfaces of the capsules were coated with P-selectin glycoprotein-ligand-1 to initiate binding interaction with P-selectin-coated planar surface with density of [Formula: see text] under linear shear flow varying from 100 to [Formula: see text]. The numerical model is based on the Immersed Boundary Method for rolling of deformable capsule in shear flow coupled with Monte Carlo simulation for receptor/ligand interaction modeled using Bell model. The results reveal that the mechanical properties of the capsule play an important role in the rolling behavior and the binding kinetics between the capsule contact surface and the substrate. The rolling behavior of the strain hardening capsules is relatively smoother and slower compared to the elastic-plastic capsules. The strain hardening capsules exhibits higher contact area at any given shear rate compared to elastic-plastic capsules. The increase in contact area leads to decrease in rolling velocity. The capsule contact surface is not in complete contact with the substrate because of thin lubrication film that is trapped between the capsule and substrate. This creates a concave shape on the bottom

  4. Osteopontin adsorption to Gram-positive cells reduces adhesion forces and attachment to surfaces under flow

    DEFF Research Database (Denmark)

    Kristensen, M F; Zeng, G; Neu, T R

    2017-01-01

    The bovine milk protein osteopontin (OPN) may be an efficient means to prevent bacterial adhesion to dental tissues and control biofilm formation. This study sought to determine to what extent OPN impacts adhesion forces and surface attachment of different bacterial strains involved in dental...

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

  6. Superhydrophobic Zr-based metallic glass surface with high adhesive force

    Science.gov (United States)

    Li, Ning; Xia, Ting; Heng, Liping; Liu, Lin

    2013-06-01

    Micro/nano hierarchical structures were constructed on Zr35Ti30Be26.75Cu8.25 metallic glass surface by silicon moulding and subsequently chemical etching. The as-formed surface exhibited both superhydrophobicity and high adhesive force towards water. The superhydrophobicity is rationalized based on the modified Cassie-Baxter model [A. B. D. Cassie and S. Baxter, Trans. Faraday Soc. 40, 546 (1944)]. The origin of the robust adhesion is described in terms of intermolecular capillary forces. The present results not only provide a method to fabricate superhydrophobic metallic glasses surface but also explore an important industrial application as dry adhesives and transport of liquid microdroplets.

  7. The surface energy of metals

    DEFF Research Database (Denmark)

    Vitos, Levente; Ruban, Andrei; Skriver, Hans Lomholt

    1998-01-01

    We have used density functional theory to establish a database of surface energies for low index surfaces of 60 metals in the periodic table. The data may be used as a consistent starting point for models of surface science phenomena. The accuracy of the database is established in a comparison...

  8. A Study of the Effects of Relative Humidity on Small Particle Adhesion to Surfaces

    Science.gov (United States)

    Whitfield, W. J.; David, T.

    1971-01-01

    Ambient dust ranging in size from less than one micron up to 140 microns was used as test particles. Relative humidities of 33% to 100% were used to condition test surfaces after loading with the test particles. A 20 psi nitrogen blowoff was used as the removal mechanism to test for particle adhesion. Particles were counted before and after blowoff to determine retention characteristics. Particle adhesion increased drastically as relative humidity increased above 50%. The greatest adhesion changes occurred within the first hour of conditioning time. Data are presented for total particle adhesion, for particles 10 microns and larger, and 50 microns and larger.

  9. Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

    Science.gov (United States)

    Zhang, Chunming; Zhao, Meihua; Wang, Libing; Qu, Lijun; Men, Yajing

    2017-04-01

    Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(Cdbnd O, Csbnd OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

  10. Effect of flagella expression on adhesion of Achromobacter piechaudii to chalk surfaces.

    Science.gov (United States)

    Nejidat, A; Saadi, I; Ronen, Z

    2008-12-01

    To examine flagella role and cell motility in adhesion of Achromobacter piechaudii to chalk. Transmission electron microscopy revealed that stationary cells have thicker and longer flagella than logarithmic cells. SDS-PAGE analysis showed that flagellin was more abundant in stationary cells than logarithmic ones. Sonication or inhibition of flagellin synthesis caused a 30% reduction in adhesion to chalk. Preincubation of chalk with flagella extracts reduced adhesion, by 50%. Three motility mutants were isolated. Mutants 94 and 153 were nonmotile, expressed normal levels of flagellin, have regular flagella and exhibited reduced adhesion. Mutant 208 expressed low levels of flagellin, no flagella and a spherical cell shape but with normal adhesion capacity. Multiple cell surface factors affect the adhesion efficiency to chalk. Flagella per se through physical interaction and through cell motility contribute to the adhesion process. The adhesion behaviour of mutant 208 suggests that cell shape can compensate for flagellar removal and motility. Physiological status affects bacterial cell surface properties and hence adhesion efficiency to chalk. This interaction is essential to sustain biodegradation activities and thus, remediation of contaminated chalk aquifers.

  11. High-energy ion implantation of polymeric fibers for modification of reinforcement-matrix adhesion

    Science.gov (United States)

    Grummon, D. S.; Schalek, R.; Ozzello, A.; Kalantar, J.; Drzal, L. T.

    1991-07-01

    We have previously reported on the effect of high-energy ion irradiation of ultrahigh molecular weight polyethylene (UHMW-PE), and Kevlar-49 polyaramid fibers, on fiber-matrix adhesion and interfacial shear strength (ISS) in epoxy matrix composites. Irradiation of UHMW-PE fibers produced large improvements in interfacial shear strength, without degrading fiber tensile strength. ISS was not generally affected in irradiated Kevlar-49, and fiber tensile strength decreased. The divergence in response between polyaramid and polyethylene relates both to differences in the mesoscopic structure of the individual fibers, and to the different forms of beam induced structural modification favored by the individual polymer chemistries. Here we report results of surface energy measurements, infrared spectroscopy analysis, and X-ray photoelectron spectroscopy studies on UHMW-PE and polyaramid fibers, irradiated to fluences between 2 × 10 12 and 5 × 10 15 cm -2 with N +, Ar +, Ti +, Na +, and He + at energies between 30 and 400 keV. UHMW-PE fibers showed a pronounced increase in the polar component of surface energy which could be associated with carbonyl, hydroxyl and hydroperoxide groups at the surface. Kevlar, on the other hand, tended toward carbonization and showed a decrease in nitrogen and oxygen concentrations and a sharp drop in polar surface energy.

  12. Effect of heat treatment on carbon fiber surface properties and fibers/epoxy interfacial adhesion

    International Nuclear Information System (INIS)

    Dai Zhishuang; Zhang Baoyan; Shi Fenghui; Li Min; Zhang Zuoguang; Gu Yizhuo

    2011-01-01

    Carbon fiber surface properties are likely to change during the molding process of carbon fiber reinforced matrix composite, and these changes could affect the infiltration and adhesion between carbon fiber and resin. T300B fiber was heat treated referring to the curing process of high-performance carbon fiber reinforced epoxy matrix composites. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the content of activated carbon atoms on treated carbon fiber surface, especially those connect with the hydroxyl decreases with the increasing heat treatment temperature. Inverse gas chromatography (IGC) analysis reveals that the dispersive surface energy γ S d increases and the polar surface energy γ S sp decreases as the heat treatment temperature increases to 200. Contact angle between carbon fiber and epoxy E51 resin, which is studied by dynamic contact angle test (DCAT) increases with the increasing heat treatment temperature, indicating the worse wettability comparing with the untreated fiber. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the treated carbon fiber/epoxy is lower than that of the untreated T300B fiber which is attributed to the decrement of the content of reactive functional groups including hydrogen group and epoxy group.

  13. Control of bacterial adhesion and growth on honeycomb-like patterned surfaces.

    Science.gov (United States)

    Yang, Meng; Ding, Yonghui; Ge, Xiang; Leng, Yang

    2015-11-01

    It is a great challenge to construct a persistent bacteria-resistant surface even though it has been demonstrated that several surface features might be used to control bacterial behavior, including surface topography. In this study, we develop micro-scale honeycomb-like patterns of different sizes (0.5-10 μm) as well as a flat area as the control on a single platform to evaluate the bacterial adhesion and growth. Bacteria strains, Escherichia coli and Staphylococcus aureus with two distinct shapes (rod and sphere) are cultured on the platforms, with the patterned surface-up and surface-down in the culture medium. The results demonstrate that the 1 μm patterns remarkably reduce bacterial adhesion and growth while suppressing bacterial colonization when compared to the flat surface. The selective adhesion of the bacterial cells on the patterns reveals that the bacterial adhesion is cooperatively mediated by maximizing the cell-substrate contact area and minimizing the cell deformation, from a thermodynamic point of view. Moreover, study of bacterial behaviors on the surface-up vs. surface-down samples shows that gravity does not apparently affect the spatial distribution of the adherent cells although it indeed facilitates bacterial adhesion. Furthermore, the experimental results suggest that two major factors, i.e. the availability of energetically favorable adhesion sites and the physical confinements, contribute to the anti-bacterial nature of the honeycomb-like patterns. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Quantification of physical (roughness) and chemical (dielectric constant) leaf surface properties relevant to wettability and adhesion.

    Science.gov (United States)

    Nairn, Justin J; Forster, W Alison; van Leeuwen, Rebecca M

    2011-12-01

    Spray droplet adhesion is dependent not only on formulation and droplet parameters but also on the surface properties (physical and chemical) of the leaf. Quantifying these leaf surface properties would aid understanding and modelling of adhesion, helping to optimise spray formulations. Fractal dimensions (FDs) were used to quantify the relative leaf surface roughness of ten plant species. Static droplet contact angles were measured on each leaf surface, and wetting tension was calculated. Chemical profiles of the leaf surfaces were developed by evaluating contact angle behaviour relative to solution dielectric constants. The FDs of Cryo-SEM micrographs taken at 300× magnification gave the best correlation with adhesion. The wetting tension intercept had a strong relationship with mean adhesion, and successfully accounted for the wettability of the outlier species. The microroughness of the leaf surface, as revealed by Cryo-SEM, can be quantified by fractal dimension analysis. However, the wetting tension intercept is a more useful universal measure of the surface properties of the leaf (including roughness) as they pertain to adhesion. The slope of the wetting tension versus dielectric constant plot allowed preliminary quantification of the chemical contribution of leaf surface dielectric behaviour to adhesion. Copyright © 2011 Society of Chemical Industry.

  15. Effect of Surface Treatment, Silane, and Universal Adhesive on Microshear Bond Strength of Nanofilled Composite Repairs.

    Science.gov (United States)

    Fornazari, I A; Wille, I; Meda, E M; Brum, R T; Souza, E M

     The aim of this study was to evaluate the effect of surface treatment and universal adhesive on the microshear bond strength of nanoparticle composite repairs.  One hundred and forty-four specimens were built with a nanofilled composite (Filtek Supreme Ultra, 3M ESPE). The surfaces of all the specimens were polished with SiC paper and stored in distilled water at 37°C for 14 days. Half of the specimens were then air abraded with Al 2 O 3 particles and cleaned with phosphoric acid. Polished specimens (P) and polished and air-abraded specimens (A), respectively, were randomly divided into two sets of six groups (n=12) according to the following treatments: hydrophobic adhesive only (PH and AH, respectively), silane and hydrophobic adhesive (PCH, ACH), methacryloyloxydecyl dihydrogen phosphate (MDP)-containing silane and hydrophobic adhesive (PMH, AMH), universal adhesive only (PU, AU), silane and universal adhesive (PCU, ACU), and MDP-containing silane and universal adhesive (PMU, AMU). A cylinder with the same composite resin (1.1-mm diameter) was bonded to the treated surfaces to simulate the repair. After 48 hours, the specimens were subjected to microshear testing in a universal testing machine. The failure area was analyzed under an optical microscope at 50× magnification to identify the failure type, and the data were analyzed by three-way analysis of variance and the Games-Howell test (α=0.05).  The variables "surface treatment" and "adhesive" showed statistically significant differences for psilane did not lead to a statistically significant increase in bond strength. Silane-containing universal adhesive on its own was as effective as any combination of silane and adhesive, particularly when applied on air-abraded surfaces.

  16. Cell adhesion on Ti surface with controlled roughness

    Directory of Open Access Journals (Sweden)

    Burgos-Asperilla, Laura

    2015-06-01

    Full Text Available In this report, the in situ interaction between Saos-2 osteoblast cells and a smooth Ti surface was examined over time. The adhesion kinetics and mechanisms of cellular proliferation were monitored by quartz crystal microbalance (QCM and electrochemical impedance spectroscopy (EIS. The rate of Saos-2 attachment on Ti surfaces, obtained from the measurements performed with the QCM, is a first-order reaction, with k=2.10−3 min−1. The impedance measurements indicate that in the absence of cells, the Ti resistance diminishes over time (7 days, due to the presence of amino acids and proteins from the culture medium that have been a dsorbed, while in the presence of osteoblasts, this decrease is much greater because of the compounds generated by the cells that accelerate the dissolution of Ti.En este trabajo, se ha estudiado la interacción in situ entre células osteoblásticas Saos-2 y una superficie de Ti de rugosidad controlada a lo largo del tiempo. El estudio de la cinética y los mecanismos de proliferación celular de adhesión se ha realizado a través de la microbalanza de cristal de cuarzo (QCM y espectroscopía de impedancia electroquímica (EIS. La velocidad de adhesión de los osteoblastos sobre la superficie de Ti obtenida a través de medidas con la QCM, sigue una reacción de primer orden, con k=2×10−3 min−1. Los ensayos de impedancia indican que, en ausencia de las células, la resistencia del Ti disminuye con el tiempo (7 días, debido a la presencia de aminoácidos y proteínas del medio de cultivo que se han adsorbido, mientras que en presencia de células, esta disminución es mucho mayor debido a los productos metabólicos generados por las células que aceleran la disolución del Ti.

  17. Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chunming, E-mail: zcm1229@126.com [College of Textiles and Clothing, Qingdao University, Qingdao 266071 (China); Sunvim Grp Co Ltd, Gaomi 261500 (China); Zhao, Meihua; Wang, Libing; Qu, Lijun [College of Textiles and Clothing, Qingdao University, Qingdao 266071 (China); Men, Yajing [Sunvim Grp Co Ltd, Gaomi 261500 (China)

    2017-04-01

    Highlights: • Air/He plasma gave hydrophilicity on polyester surface and decreased contact angle to 18°. • The roughness of polyester increased and pit-like structures appeared on the surface after plasma treatment. • XPS confirmed the generation of new functional groups on polyester fabric. • The improved pigment color yield and anti-bleeding performance were contributed by the alteration of pigment adhesion. • The air/He plasma was more effective than air plasma at the same treatment time. - Abstract: Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(C=O, C−OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

  18. Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

    International Nuclear Information System (INIS)

    Zhang, Chunming; Zhao, Meihua; Wang, Libing; Qu, Lijun; Men, Yajing

    2017-01-01

    Highlights: • Air/He plasma gave hydrophilicity on polyester surface and decreased contact angle to 18°. • The roughness of polyester increased and pit-like structures appeared on the surface after plasma treatment. • XPS confirmed the generation of new functional groups on polyester fabric. • The improved pigment color yield and anti-bleeding performance were contributed by the alteration of pigment adhesion. • The air/He plasma was more effective than air plasma at the same treatment time. - Abstract: Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(C=O, C−OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

  19. Potential dependent adhesion forces on bare and underpotential deposition modified electrode surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Serafin, J.M.; Hsieh, S.J.; Monahan, J.; Gewirth, A.A. [Univ. of Illinois, Urbana, IL (United States)

    1998-12-03

    Adhesion force measurements are used to determine the potential dependence of the force of adhesion between a Si{sub 3}N{sub 4} cantilever and a Au(111) surface modified by the underpotential deposition (upd) of Bi or Cu in acid solution or by oxide formation. The measured work of adhesion is near zero for most of the potential region examined in Bi upd but rises after the formation of a full Bi monolayer. The work of adhesion is high at positive potentials for Cu upd but then decreases as the Cu partial and full monolayers are formed. The work of adhesion is low in the oxide region on Au(111) but rises following the sulfate disordering transition at 1.1 V vs NHE. These results are interpreted in terms of the degree of solvent order on the electrode surface.

  20. Electrochemical & osteoblast adhesion study of engineered TiO{sub 2} nanotubular surfaces on titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Zia Ur [School of Engineering and Technology, Central Michigan University, Mt. Pleasant, MI (United States); Haider, Waseem, E-mail: haide1w@cmich.edu [School of Engineering and Technology, Central Michigan University, Mt. Pleasant, MI (United States); Pompa, Luis [Department of Mechanical Engineering, University of Texas–Pan American, Edinburg, TX (United States); Deen, K.M. [Department of Metallurgy & Materials Engineering, CEET, University of the Punjab, 54590 Lahore (Pakistan); Department of Materials Engineering, University of British Columbia, Vancouver, BC V6T 1Z4 (Canada)

    2016-01-01

    TiO{sub 2} nanotubes were grafted on the surface of cpTi, Ti6Al4V and Ti6Al4V-ELI with the aim to provide a new podium for human pre-osteoblast cell (MC3T3) adhesion and proliferation. The surface morphology and chemistry of these alloys were examined with scanning electron microscopy and energy dispersive x-ray spectroscopy. TiO{sub 2} nanotubes were further characterized by cyclic potentiodynamic polarization tests and electrochemical impedance spectroscopy. The vertically aligned nanotubes were subjected to pre-osteoblast cell proliferation in order to better understand cell–material interaction. The study demonstrated that these cells interact differently with nanotubes of different titanium alloys. The significant acceleration in the growth rate of pre-osteoblast cell adhesion and proliferation is also witnessed. Additionally, the cytotoxicity of the leached metal ions was evaluated by using a tetrazolium-based bio-assay, MTS. Each group of data was operated for p < 0.05, concluded one way ANOVA to investigate the significance difference. - Highlights: • TiO{sub 2} nanotubes were grafted on cpTi, Ti6Al4V and Ti6Al4V-ELI via anodization. • MC3T3 cells interact differently with nanotubes of different titanium alloys. • TiO{sub 2} nanotubes have a positive impact on the osteoblast cell viability.

  1. Enterococcus faecalis surface proteins determine its adhesion mechanism to bile drain materials.

    Science.gov (United States)

    Waar, Karola; van der Mei, Henny C; Harmsen, Hermie J M; Degener, John E; Busscher, Henk J

    2002-06-01

    An important step in infections associated with biliary drains is adhesion of micro-organisms to the surface. In this study the role of three surface proteins of Enterococcus faecalis (enterococcal surface protein, aggregation substances 1 and 373) in the adhesion to silicone rubber, fluoro-ethylene-propylene and polyethylene was examined. Four isogenic E. faecalis strains with and without aggregation substances and one strain expressing enterococcal surface protein were used. The kinetics of enterococcal adhesion to the materials was measured in situ in a parallel plate flow chamber. Initial deposition rates were similar for all strains, whereas the presence of surface proteins increased the total number of adhering bacteria. Nearest neighbour analysis demonstrated that enterococci expressing the whole sex-pheromone plasmid encoding aggregation substances 1 or 373 adhered in higher numbers through mechanisms of positive cooperativity, which means that adhesion of bacteria enhances the probability of adhesion of other bacteria near these bacteria. Enterococci with the enterococcal surface protein did not adhere through this mechanism. These findings indicate that the surface proteins of E. faecalis play a key role in the adhesion to bile drains and bile drain associated infections.

  2. Biomimetic Fluorocarbon Surfactant Polymers Reduce Platelet Adhesion on PTFE/ePTFE Surfaces

    Science.gov (United States)

    Wang, Shuwu; Gupta, Anirban Sen; Sagnella, Sharon; Barendt, Pamela M.; Kottke-Marchant, Kandice; Marchant, Roger E.

    2010-01-01

    We describe a series of fluorocarbon surfactant polymers designed as surface-modifying agents for improving the thrombogenicity of ePTFE vascular graft materials by the reduction of platelet adhesion. The surfactant polymers consist of a poly(vinyl amine) backbone with pendent dextran and perfluoroundecanoyl branches. Surface modification is accomplished by a simple dip-coating process in which surfactant polymers undergo spontaneous surface-induced adsorption and assembly on PTFE/ePTFE surface. The adhesion stability of the surfactant polymer on PTFE was examined under dynamic shear conditions in PBS and human whole blood with a rotating disk system. Fluorocarbon surfactant polymer coatings with three different dextran to perfluorocarbon ratios (1:0.5, 1:1 and 1:2) were compared in the context of platelet adhesion on PTFE/ePTFE surface under dynamic flow conditions. Suppression of platelet adhesion was achieved for all three coated surfaces over the shear-stress range of 0–75 dyn/cm2 in platelet-rich plasma (PRP) or human whole blood. The effectiveness depended on the surfactant polymer composition such that platelet adhesion on coated surfaces decreased significantly with increasing fluorocarbon branch density at 0 dyn/cm2. Our results suggest that fluorocarbon surfactant polymers can effectively suppress platelet adhesion and demonstrate the potential application of the fluorocarbon surfactant polymers as non-thrombogenic coatings for ePTFE vascular grafts. PMID:19323880

  3. Gecko toe and lamellar shear adhesion on macroscopic, engineered rough surfaces.

    Science.gov (United States)

    Gillies, Andrew G; Henry, Amy; Lin, Hauwen; Ren, Angela; Shiuan, Kevin; Fearing, Ronald S; Full, Robert J

    2014-01-15

    The role in adhesion of the toes and lamellae - intermediate-sized structures - found on the gecko foot remains unclear. Insight into the function of these structures can lead to a more general understanding of the hierarchical nature of the gecko adhesive system, but in particular how environmental topology may relate to gecko foot morphology. We sought to discern the mechanics of the toes and lamellae by examining gecko adhesion on controlled, macroscopically rough surfaces. We used live Tokay geckos, Gekko gecko, to observe the maximum shear force a gecko foot can attain on an engineered substrate constructed with sinusoidal patterns of varying amplitudes and wavelengths in sizes similar to the dimensions of the toes and lamellae structures (0.5 to 6 mm). We found shear adhesion was significantly decreased on surfaces that had amplitudes and wavelengths approaching the lamella length and inter-lamella spacing, losing 95% of shear adhesion over the range tested. We discovered that the toes are capable of adhering to surfaces with amplitudes much larger than their dimensions even without engaging claws, maintaining 60% of shear adhesion on surfaces with amplitudes of 3 mm. Gecko adhesion can be predicted by the ratio of the lamella dimensions to surface feature dimensions. In addition to setae, remarkable macroscopic-scale features of gecko toes and lamellae that include compliance and passive conformation are necessary to maintain contact, and consequently, generate shear adhesion on macroscopically rough surfaces. Findings on the larger scale structures in the hierarchy of gecko foot function could provide the biological inspiration to drive the design of more effective and versatile synthetic fibrillar adhesives.

  4. Femtosecond laser surface texturing of titanium as a method to reduce the adhesion of Staphylococcus aureus and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, Alexandre [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Elie, Anne-Marie [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Plawinski, Laurent [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Serro, Ana Paula [Instituto Superior Técnico, Universidade de Lisboa, CQE-Centro de Química Estrutural, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Botelho do Rego, Ana Maria [Instituto Superior Técnico, Universidade de Lisboa, CQFM-Centro de Química-Física Molecular and Institute of Nanoscience and Nanotechnology - IN, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Almeida, Amélia [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Urdaci, Maria C. [Bordeaux University, CBMN UMR 5248, CNRS, Bordeaux Science Agro, 1 Rue du G. de Gaulle, 33170 Gradignan (France); Durrieu, Marie-Christine [Bordeaux University, Institute of Chemistry & Biology of Membranes & Nanoobjects (CBMN UMR 5248, CNRS), European Institute of Chemistry and Biology, 2 Rue Robert Escarpit, 33607 Pessac (France); Vilar, Rui, E-mail: rui.vilar@tecnico.ulisboa.pt [Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

    2016-01-01

    Graphical abstract: - Highlights: • The short-term adhesion of Staphylococcus aureus onto femtosecond laser textured surfaces of titanium was investigated. • The laser textured surfaces consist of laser-induced periodic surface structures (LIPSS) and nanopillars. • The laser treatment enhances the hydrophilicity and the surface free energy of the material. • The laser treatment reduces significantly the adhesion of S. aureus and biofilm formation. • Femtosecond laser surface texturing of titanium is a simple and promising method for endowing dental and orthopedic implants with antibacterial properties. - Abstract: The aim of the present work was to investigate the possibility of using femtosecond laser surface texturing as a method to reduce the colonization of Grade 2 Titanium alloy surfaces by Staphylococcus aureus and the subsequent formation of biofilm. The laser treatments were carried out with a Yb:KYW chirped-pulse-regenerative amplification laser system with a central wavelength of 1030 nm and a pulse duration of 500 fs. Two types of surface textures, consisting of laser-induced periodic surface structures (LIPSS) and nanopillars, were produced. The topography, chemical composition and phase constitution of these surfaces were investigated by atomic force microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, and X-ray diffraction. Surface wettability was assessed by the sessile drop method using water and diiodomethane as testing liquids. The response of S. aureus put into contact with the laser treated surfaces in controlled conditions was investigated by epifluorescence microscopy and scanning electron microscopy 48 h after cell seeding. The results achieved show that the laser treatment reduces significantly the bacterial adhesion to the surface as well as biofilm formation as compared to a reference polished surfaces and suggest that femtosecond laser texturing is a simple and promising method

  5. Controllable load sharing for soft adhesive interfaces on three-dimensional surfaces

    Science.gov (United States)

    Song, Sukho; Drotlef, Dirk-Michael; Majidi, Carmel; Sitti, Metin

    2017-05-01

    For adhering to three-dimensional (3D) surfaces or objects, current adhesion systems are limited by a fundamental trade-off between 3D surface conformability and high adhesion strength. This limitation arises from the need for a soft, mechanically compliant interface, which enables conformability to nonflat and irregularly shaped surfaces but significantly reduces the interfacial fracture strength. In this work, we overcome this trade-off with an adhesion-based soft-gripping system that exhibits enhanced fracture strength without sacrificing conformability to nonplanar 3D surfaces. Composed of a gecko-inspired elastomeric microfibrillar adhesive membrane supported by a pressure-controlled deformable gripper body, the proposed soft-gripping system controls the bonding strength by changing its internal pressure and exploiting the mechanics of interfacial equal load sharing. The soft adhesion system can use up to ˜26% of the maximum adhesion of the fibrillar membrane, which is 14× higher than the adhering membrane without load sharing. Our proposed load-sharing method suggests a paradigm for soft adhesion-based gripping and transfer-printing systems that achieves area scaling similar to that of a natural gecko footpad.

  6. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Tao [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Liu, Yong [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Zhu, Yan, E-mail: zhuyan@kmust.edu.cn [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Yang, De-Quan, E-mail: dequan.yang@gmail.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, 253 Xuefu Rd, Kunming, Yunnan, 650093 (China); Solmont Technology Wuxi Co., Ltd. 228 Linghu Blvd. Tianan Tech Park, A1-602, Xinwu District, Wuxi, Jiangsu 214135 (China); Sacher, Edward [Regroupement Québécois de Matériaux de Pointe, Department of Engineering Physics, École Polytechnique de Montréal, Case Postale 6079, succursale Centre-Ville, Montréal, Québec H3C 3A7 (Canada)

    2017-07-31

    Highlights: • A two-step process has been developed to enhance the adhesion of immobilized Ag NPs to the PET surface. • The method is simple, easy to use and low-cost for mass production. • The increased density of active sites (−OH, −CH=O and COOH) at the PET surface, after plasma treatment, permits increased reaction with 3-aminopropyltriethoxysilane (APTES). • The presence of APTES with high surface density permits −NH{sub 2}-Ag complex formation, increasing the adhesion of the Ag NPs. - Abstract: Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (−OH, −CH=O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose −NH{sub 2} groups were then able to form a bonding complex with the Ag NPs.

  7. Effect of surface modification of siliconeon Staphylococcus epidermidis adhesion and colonization.

    Science.gov (United States)

    Tang, Haiying; Cao, Ting; Wang, Anfeng; Liang, Xuemei; Salley, Steven O; McAllister, James P; Ng, K Y Simon

    2007-03-15

    Cerebrospinal fluid (CSF) shunts for the treatment of hydrocephalus are generally made of silicone rubber. The growth of bacterial colonies on the silicone surface leads to frequent CSF shunt complications. A systematic study of the effect of the surface modification of silicone on Staphylococcus epidermidis adhesion and colonization was performed for different incubation times by means of colony counting and scanning electron microscopy (SEM). Silicone was modified with different biopolymers and silanes, including heparin, hyaluronan, octadecyltrichlorosilane (OTS), and fluoroalkylsilane (FAS) to provide a stable and biocompatible surface with different surface functional groups and degrees of hydrophobicity. The modified silicone surfaces were studied by using contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). After 4 and 8 h of incubation, the FAS- and OTS-coated silicone and the hyaluronan coated OTS/silicone surfaces showed significantly reduced bacterial adhesion and colonization compared to blank silicone by both quantification methods. However, the heparin coated OTS/silicone showed significantly increased bacterial adhesion. These results indicate that the nature of the surface functional group and surface roughness determine the extent of bacterial adhesion and colonization. However, the degree of hydrophobicity of the surface did not appear to play a determining role in bacterial adhesion and colonization.

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

  10. Adhesion of CO2 on hydrated mineral surfaces and its implications to geologic carbon sequestration

    Science.gov (United States)

    Wang, S.; Clarens, A. F.; Tao, Z.; Persily, S. M.

    2013-12-01

    Most mineral surfaces are water wetting, which has important implications for the transport of non-aqueous phase liquids, such as CO2, through porous media. In this work, contact angle experiments were carried out wherein unusual wetting behavior was observed between mineral surfaces and liquid or supercritical CO2 under certain geochemical conditions. This behavior can be understood in the context of adhesion between the CO2 and the mineral surface. When adhesion occurs, the wettability characteristics of the surfaces are significantly altered. More importantly, the CO2 exhibits a strong affinity for the surface and is highly resistant to shear forces in the aqueous phase. A static pendant drop method was used on a variety of polished mineral surfaces to measure contact angles. The composition of the aqueous phase (e.g., pH, ionic strength) and the characteristics of the mineral surface (e.g., composition, roughness), were evaluated to understand their impact on the prevalence of adhesion. Pressure and temperature conditions were selected to represent those that would be prevalent in geologic carbon sequestration (GCS) or during leakage from target repositories. Adhesion was widely observed on phlogopite mica, silica, and calcite surfaces with roughness on the order of ~10 nanometers. CO2 exhibited no adhesion on mineral surfaces with higher roughness (e.g., quartz). On smoother surfaces, the CO2 is thought to have more effective contact area with the mineral, enabling the weak van der Waals forces that drive most adhesion processes. Brine chemistry also had an important role in controlling CO2 adhesion. Increases in CO2 partial pressure and ionic strength both increased the incidence of adhesion. The addition of strong acid or strong base permanently inhibited the development of adhesion. These results suggest that the development of adhesion between the CO2 and the mineral surface is dependent on the integrity and thickness of the hydration layer between the CO2

  11. Improved adhesion of Ag NPs to the polyethylene terephthalate surface via atmospheric plasma treatment and surface functionalization

    Science.gov (United States)

    Shen, Tao; Liu, Yong; Zhu, Yan; Yang, De-Quan; Sacher, Edward

    2017-07-01

    Ag nanoparticles (NPs) have been widely applied, as important antibacterial materials, on textile and polymer surfaces. However, their adhesion to nonreactive polymer surfaces is generally too weak for many applications. Here, we propose a two-step process, atmospheric plasma treatment followed by a surface chemical modification process, which enhances their adhesion to polyethylene terephthalate (PET) surfaces. We found that, compared to either plasma treatments or surface chemical functionalizations, alone, this combination greatly enhanced their adhesion. The plasma treatment resulted in an increase of active sites (sbnd OH, sbnd CHdbnd O and COOH) at the PET surface, permitting increased bonding to 3-aminopropyltriethoxysilane (APTES), whose sbnd NH2 groups were then able to form a bonding complex with the Ag NPs.

  12. Influence of surface treatments on the surface properties of different zirconia cores and adhesion of zirconia-veneering ceramic systems.

    Science.gov (United States)

    Elsaka, Shaymaa E

    2013-10-01

    The aim of this study was to assess the influence of surface treatments on the surface characteristics of different zirconia cores and the adhesion of the zirconia-veneering ceramic systems by means of strain energy release rate (G-value, J/m(2)). Three types of zirconia cores (NANOZR (NZ), Vita In-Ceram YZ (VZ), and IPS e.max ZirCAD (IZ)) were used. The specimens were divided into four groups in each test according to the surface treatment used; Gr 1 (control; no treatment), Gr 2 (sandblasted), Gr 3 (CH2Cl2 for 60min), and Gr 4 (experimental hot etching solution for 60min). AFM, SEM, EDS, and XRD were carried out. Two types of veneering ceramics (Vita VM9 (V9) and IPS e.max Ceram (IC)) were used for testing the adhesion. The G-value (J/m(2)) was measured with a four-point bending configuration. Following fracture testing specimens were examined with SEM. Data were analyzed using ANOVA and Tukey's test. NZ treated with the experimental hot etching solution showed the highest Ra values (206.06±9.98nm) compared with the other groups (Pveneering ceramic systems. The experimental hot etching solution could be considered as alternative treatment modality to sandblasting for zirconia cores to avoid phase transition at the surface from tetragonal to monoclinic that may be detrimental for the longevity of the zirconia-veneering ceramic restoration. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. Role of lactobacillus cell surface hydrophobicity as probed by AFM in adhesion to surfaces at low and high ionic strength

    NARCIS (Netherlands)

    Vadillo Rodriguez, Virginia; Busscher, Hendrik; van der Mei, Henderina; Norde, Willem; de Vries, Jacob

    2005-01-01

    The S-layer present at the outermost cell surface of some lactobacillus species is known to convey hydrophobicity to the lactobacillus cell surface. Yet, it is commonly found that adhesion of lactobacilli to solid substrata does not proceed according to expectations based on cell surface

  14. Role of lactobacillus cell surface hydrophobicity as probed by AMF in adhesion to surfaces at low and high ionic strength

    NARCIS (Netherlands)

    Vadillo-Rodriguez, V.; Busscher, H.J.; Meij, van der H.C.; Vries, de J.; Norde, W.

    2005-01-01

    The S-layer present at the outermost cell surface of some lactobacillus species is known to convey hydrophobicity to the lactobacillus cell surface. Yet, it is commonly found that adhesion of lactobacilli to solid substrata does not proceed according to expectations based on cell surface

  15. Effects of surface roughness and film thickness on the adhesion of a bioinspired nanofilm

    Science.gov (United States)

    Peng, Z. L.; Chen, S. H.

    2011-05-01

    Inspired by the gecko's climbing ability, adhesion between an elastic nanofilm with finite length and a rough substrate with sinusoidal roughness is studied in the present paper, considering the effects of substrate roughness and film thickness. It demonstrates that the normal adhesion force of the nanofilm on a rough substrate depends significantly on the geometrical parameters of the substrate. When the film length is larger than the wavelength of the sinusoidal roughness of the substrate, the normal adhesion force decreases with increasing surface roughness, while the normal adhesion force initially decreases then increases if the wavelength of roughness is larger than the film length. This finding is qualitatively consistent with a previously interesting experimental observation in which the adhesion force of the gecko spatula is found to reduce significantly at an intermediate roughness. Furthermore, it is inferred that the gecko may achieve an optimal spatula thickness not only to follow rough surfaces, but also to saturate the adhesion force. The results in this paper may be helpful for understanding how geckos overcome the influence of natural surface roughness and possess such adhesion to support their weights.

  16. Studies on polyurethane adhesives and surface modification of hydrophobic substrates

    Science.gov (United States)

    Krishnamoorthy, Jayaraman

    This thesis work deals with (a) Curing of reactive, hot-melt polyurethane adhesives and (b) Adsorption studies using different interactions. Research on polyurethanes involves characterization of polyurethane prepolymers and a novel mechanism to cure isocyanate-terminated polyurethane prepolymer by a "trigger" mechanism. Curing of isocyanate-terminated polyurethane prepolymers has been shown to be influenced by morphology and environmental conditions such as temperature and relative humidity. Although the initial composition, final morphology and curing kinetics are known, information regarding the intermediate prepolymer mixture is yet to be established. Polyurethane prepolymers prepared by the reaction of diisocyanates with the primary hydroxyls of polyester diol (PHMA) and secondary hydroxyls of polyether diol (PPG) were characterized. The morphology and crystallization kinetics of a polyurethane prepolymer was compared with a blend of PPG prepolymer (the product obtained by the reaction of PPG with diisocyanate) and a PHMA prepolymer (the product obtained by the reaction of PHMA with diisocyanate) to study the effect of copolymer formed in the polyurethane prepolymer on the above-mentioned properties. Although the morphology of the polyurethane prepolymer is determined in the first few minutes of application, the chemical curing of isocyanate-terminated prepolymer occurs over hours to days. In the literature, different techniques are described to follow the curing kinetics. But there is no established technique to control the curing of polyurethane prepolymer. To make the curing process independent of environmental factors, a novel approach using a trigger mechanism was designed and implemented by using ammonium salts as curing agents. Ammonium salts that are stable at room temperature but decompose on heating to yield active hydrogen-containing compounds, NH3 and H2O, were used as 'Trojan horses' to cure the prepolymer chemically. Research on adsorption

  17. In vitro study of Streptococcus mutans adhesion on composite resin coated with three surface sealants

    Directory of Open Access Journals (Sweden)

    Da Hye Kim

    2017-02-01

    Full Text Available Objectives Although the coating of surface sealants to dental composite resin may potentially reduce bacterial adhesion, there seems to be little information regarding this issue. This preliminary in vitro study investigated the adhesion of Streptococcus mutans (S. mutans on the dental composite resins coated with three commercial surface sealants. Materials and Methods Composite resin (Filtek Z250 discs (8 mm in diameter, 1 mm in thickness were fabricated in a mold covered with a Mylar strip (control. In group PoGo, the surfaces were polished with PoGo. In groups PS, OG, and FP, the surfaces polished with PoGo were coated with the corresponding surface sealants (PermaSeal, PS; OptiGuard, OG; Fortify Plus, FP. The surfaces of the materials and S. mutans cells were characterized by various methods. S. mutans adhesion to the surfaces was quantitatively evaluated using flow cytometry (n = 9. Results Group OG achieved the lowest water contact angle among all groups tested (p 0.05 or significantly lower (group OG, p < 0.001 bacterial adhesion when compared with the control group. Conclusions The application of the surface sealants significantly reduced S. mutans adhesion to the composite resin polished with the PoGo.

  18. Low Pressure DC Glow Discharge Air Plasma Surface Treatment of Polyethylene (PE) Film for Improvement of Adhesive Properties

    International Nuclear Information System (INIS)

    Pandiyaraj, Krishnasamy Navaneetha; Yoganand, Paramasivam; Selvarajan, Vengatasamy; Deshmukh, Rajendrasing R.; Balasubramanian, Suresh; Maruthamuthu, Sundaram

    2013-01-01

    The present work deals with the change in surface properties of polyethylene (PE) film using DC low pressure glow discharge air plasma and makes it useful for technical applications. The change in hydrophilicity of the modified PE film surface was investigated by measuring contact angle and surface energy as a function of exposure time. Changes in the morphological and chemical composition of PE films were analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The improvement in adhesion was studied by measuring T-peel and lap-shear strength. The results show that the wettability and surface energy of the PE film has been improved due to the introduction of oxygen-containing polar groups and an increase in surface roughness. The XPS result clearly shows the increase in concentration of oxygen content and the formation of polar groups on the polymer surface. The AFM observation on PE film shows that the roughness of the surface increased due to plasma treatment. The above morphological and chemical changes enhanced the adhesive properties of the PE film surfaces, which was confirmed by T-peel and lap-shear tests.

  19. From petal effect to lotus effect: a facile solution immersion process for the fabrication of super-hydrophobic surfaces with controlled adhesion

    Science.gov (United States)

    Cheng, Zhongjun; Du, Ming; Lai, Hua; Zhang, Naiqing; Sun, Kening

    2013-03-01

    In this paper, a convenient approach based on the reaction between an alkyl thiol and hierarchical structured Cu(OH)2 substrates is reported for the fabrication of super-hydrophobic surfaces with controlled adhesion. This reaction can etch the Cu(OH)2 microstructures and simultaneously introduce a coating with low surface energy. By simply controlling the reaction time or the chain length of the thiol, super-hydrophobic surfaces with controlled adhesion can be achieved, and the adhesive force between the surface and the water droplet can be adjusted from extreme low (~14 μN) to very high (~65 μN). The tunable effect of the adhesion is ascribed to the different wetting states for the droplet on the surface that results from the change of the morphology and microstructure scale after the thiolate reaction. Noticeably, the as-prepared surfaces are acid/alkali-resisting; the acidic and basic water droplets have similar contact angles and adhesive forces to that of the neutral water droplet. Moreover, we demonstrate a proof of water droplet transportation for application in droplet-based microreactors via our surfaces. We believe that the results reported here would be helpful for the further understanding of the effect of wetting states on the surface adhesion and the fabrication principle for a super-hydrophobic surface with controlled adhesion.In this paper, a convenient approach based on the reaction between an alkyl thiol and hierarchical structured Cu(OH)2 substrates is reported for the fabrication of super-hydrophobic surfaces with controlled adhesion. This reaction can etch the Cu(OH)2 microstructures and simultaneously introduce a coating with low surface energy. By simply controlling the reaction time or the chain length of the thiol, super-hydrophobic surfaces with controlled adhesion can be achieved, and the adhesive force between the surface and the water droplet can be adjusted from extreme low (~14 μN) to very high (~65 μN). The tunable effect of the

  20. Template assisted surface microstructuring of flowable dental composites and its effect on microbial adhesion properties.

    Science.gov (United States)

    Frenzel, Nadja; Maenz, Stefan; Sanz Beltrán, Vanesa; Völpel, Andrea; Heyder, Markus; Sigusch, Bernd W; Lüdecke, Claudia; Jandt, Klaus D

    2016-03-01

    Despite their various advantages, such as good esthetic properties, absence of mercury and adhesive bonding to teeth, modern dental composites still have some drawbacks, e.g., a relatively high rate of secondary caries on teeth filled with composite materials. Recent research suggests that microstructured biomaterials surfaces may reduce microbial adhesion to materials due to unfavorable physical material-microbe interactions. The objectives of this study were, therefore, to test the hypotheses that (i) different surface microstructures can be created on composites by a novel straightforward approach potentially suitable for clinical application and (ii) that these surface structures have a statistically significant effect on microbial adhesion properties. Six different dental composites were initially tested for their suitability for microstructuring by polydimethylsiloxane (PDMS) templates. Each composite was light-cured between a glass slide and a microstructured PDMS template. The nano-hybrid composite Grandio Flow was the only tested composite with satisfying structurability, and was therefore used for the bacterial adhesion tests. Composites samples were structured with four different microstructures (flat, cubes, linear trapezoid structures, flat pyramids) and incubated for 4h in centrifuged saliva. The bacterial adherence was then characterized by colony forming units (CFUs) and scanning electron microscopy (SEM). All four microstructures were successfully transferred from the PDMS templates to the composite Grandio Flow. The CFU-test as well as the quantitative analysis of the SEM images showed the lowest bacterial adhesion on the flat composite samples. The highest bacterial adhesion was observed on the composite samples with linear trapezoid structures, followed by flat pyramids and cubes. The microstructure of dental composite surfaces statistically significantly influenced the adhesion of oral bacteria. Modifying the composite surface structure may be

  1. Regulation of body weight and energy homeostasis by neuronal cell adhesion molecule 1

    NARCIS (Netherlands)

    Rathjen, Thomas; Yan, Xin; Kononenko, Natalia L.; Ku, Min-Chi; Song, Kun; Ferrarese, Leiron; Tarallo, Valentina; Puchkov, Dmytro; Kochlamazashvili, Gaga; Brachs, Sebastian; Varela, Luis; Szigeti-Buck, Klara; Yi, Chun-Xia; Schriever, Sonja C.; Tattikota, Sudhir Gopal; Carlo, Anne Sophie; Moroni, Mirko; Siemens, Jan; Heuser, Arnd; van der Weyden, Louise; Birkenfeld, Andreas L.; Niendorf, Thoralf; Poulet, James F. A.; Horvath, Tamas L.; Tschöp, Matthias H.; Heinig, Matthias; Trajkovski, Mirko; Haucke, Volker; Poy, Matthew N.

    2017-01-01

    Susceptibility to obesity is linked to genes regulating neurotransmission, pancreatic beta-cell function and energy homeostasis. Genome-wide association studies have identified associations between body mass index and two loci near cell adhesion molecule 1 (CADM1) and cell adhesion molecule 2

  2. Determination of adhesive specific energy of erythrocyte agglutination by laser retrodiffusion

    Science.gov (United States)

    Rasia, R. J.; de Isla, N.; Altube, L.; Stoltz, J. F.; Valverde, J.

    2003-05-01

    The quality of an antibody is related to its affinity expressed by the equilibrium constant. The biological activity of an antibody can be estimated by the strength of antigen-antibody bridges. An optical method is proposed to estimate the specific binding energy using the dissociation behavior of suspended RBC agglutinates in a shear flow and measuring laser backscattering. A constant increase of intensity was observed when the shear stress raises, pointing to a progressive dissociation of RBC agglutinates into smaller ones. The final break-up of two-cell rouleaux is produced at critical shear stress ( τc), which reflects the mechanical action required to dissociate the molecular bridges between cells. The critical shear stress permitted to define the specific surface adhesive energy ( Γ) by using the Derjaguin relation. The determination of τc provides a good way to assess the functional characterization of specific immunoglobulins, which could be very useful for antibody quality control.

  3. Laser surface modification of silicone rubber to reduce platelet adhesion in vitro.

    Science.gov (United States)

    Khorasani, M T; Mirzadeh, H

    2004-01-01

    To improve the blood compatibility, the surface of polydimethylsiloxane (PDMS) films were irradiated using a CO2-pulsed laser. Acrylamide (AAm) was grafted onto a pre-irradiated surface. The AAm-grafted and laser-treated films were characterized using different techniques. Platelet adhesion and activation onto the AAm-grafted PDMS, laser-treated (ungrafted) and unmodified PDMS film surfaces were compared. Data from in vitro assays indicated that the platelet adhesion was reduced on the AAm-grafted PDMS and laser treated PDMS films in comparison with the unmodified PDMS. The laser-irradiated sample showed the minimum platelet adhesion. It seems that laser irradiation onto a silicone rubber surface is a versatile technique to produce anti-thrombogenic surface for biomaterial applications.

  4. Effects of mechanical and chemical surface treatments on the resin-glass ceramic adhesion properties.

    Science.gov (United States)

    Sattabanasuk, Vanthana; Charnchairerk, Paleenee; Punsukumtana, Lada; Burrow, Michael F

    2017-08-01

    Intraoral repair of fractured ceramic restorations using resin composite is practical for dental treatment. In the present study, we investigated whether differences in surface treatments for glass ceramic would affect resin adhesion. Leucite-reinforced glass ceramic plates (IPS Empress Esthetic) were ground with 320-grit silicon carbide paper, cleaned using phosphoric acid, and then etched with hydrofluoric acid (IPS Ceramic Etching Gel) or left unetched, and silanized using silane coupling agent (RelyX Ceramic Primer) or kept unsilanized. Either conventional (Adper Scotchbond Multi-Purpose) or universal (Scotchbond Universal) adhesive was used to bond the resin composite to ceramic surfaces. Specimens were subjected to microshear test after 37°C water storage for 24 h, and fractured surfaces were examined. Ceramic surface hydrophobicity after treatments was verified with contact angle measurements. Data were analyzed using anova and Tukey's tests. Regardless of the adhesive tested, hydrofluoric acid-etched ceramics showed higher bond strengths. Ceramic primer application improved resin bonding, even in non-etched groups, and also influenced fractography (P ceramics treated with ceramic primer were higher than those treated with silane-containing universal adhesive (P resin adhesion to glass ceramic. Universal adhesive seems to not function in the same manner as a silane coupling agent. © 2016 John Wiley & Sons Australia, Ltd.

  5. Nylon-3 copolymers that generate cell-adhesive surfaces identified by library screening.

    Science.gov (United States)

    Lee, Myung-Ryul; Stahl, Shannon S; Gellman, Samuel H; Masters, Kristyn S

    2009-11-25

    Polymers in the nylon-3 family contain subunits derived from beta-amino acids, which are linked to one another via amide bonds. Thus, the nylon-3 backbone is homologous to the alpha-amino acid-based backbone of proteins. This molecular-level homology suggests that nylon-3 materials might be intrinsically protein-mimetic. The experiments described here explore this prospect in the context of cell adhesion, with tissue engineering as a long-range goal. We have evaluated a small library of sequence-random nylon-3 copolymers for the ability to render surfaces attractive to NIH 3T3 fibroblast adhesion and spreading. Library screening was accomplished in a high-throughput, parallel mode via attachment of the copolymers in a two-dimensional array to a modified glass surface. Significant variations in fibroblast adhesion and spreading were observed as a function of nylon-3 subunit identity and proportion. Several of the nylon-3 copolymers supported cell adhesion and morphology that was comparable, or even superior, to that achieved on positive control substrates such as tissue culture polystyrene and collagen-coated glass. Moreover, studies conducted under serum-free conditions demonstrated that specific nylon-3 derivatives supported cell adhesion independently of serum protein adsorption. Although cell adhesion was diminished in the absence of serum, particular copolymers demonstrated an ability to support substantially greater cell adhesion than any of the other conditions, including the positive controls. The nylon-3 copolymers that were most effective at promoting adhesion to a modified glass surface proved also to be effective at promoting adhesion when attached to a PEG-based hydrogel, demonstrating the potential for these copolymers to be used in tissue engineering applications.

  6. Nylon-3 Co-Polymers that Generate Cell-Adhesive Surfaces Identified by Library Screening

    Science.gov (United States)

    Lee, Myung-Ryul; Stahl, Shannon S.; Gellman, Samuel H.; Masters, Kristyn S.

    2010-01-01

    Polymers in the nylon-3 family contain subunits derived from β-amino acids, which are linked to one another via amide bonds. Thus, the nylon-3 backbone is homologous to the α-amino acid-based backbone of proteins. This molecular-level homology suggests that nylon-3 materials might be intrinsically protein-mimetic. The experiments described here explore this prospect in the context of cell adhesion, with tissue engineering as a long-range goal. We have evaluated a small library of sequence-random nylon-3 copolymers for the ability to render surfaces attractive to NIH 3T3 fibroblast adhesion and spreading. Library screening was accomplished in a high-throughput, parallel mode via attachment of the copolymers in a two-dimensional array to a modified glass surface. Significant variations in fibroblast adhesion and spreading were observed as a function of nylon-3 subunit identity and proportion. Several of the nylon-3 copolymers supported cell adhesion and morphology that was comparable, or even superior, to that achieved on positive control substrates such as tissue culture polystyrene and collagen-coated glass. Moreover, studies conducted under serum-free conditions demonstrated that specific nylon-3 derivatives supported cell adhesion independently of serum protein adsorption. Although cell adhesion was diminished in the absence of serum, particular copolymers demonstrated an ability to support substantially greater cell adhesion than any of the other conditions, including the positive controls. The nylon-3 copolymers that were most effective at promoting adhesion to a modified glass surface proved also to be effective at promoting adhesion when attached to a PEG-based hydrogel, demonstrating the potential for these copolymers to be used in tissue engineering applications. PMID:19886604

  7. Covalent and density-controlled surface immobilization of E-cadherin for adhesion force spectroscopy.

    Directory of Open Access Journals (Sweden)

    Dagmar Fichtner

    Full Text Available E-cadherin is a key cell-cell adhesion molecule but the impact of receptor density and the precise contribution of individual cadherin ectodomains in promoting cell adhesion are only incompletely understood. Investigating these mechanisms would benefit from artificial adhesion substrates carrying different cadherin ectodomains at defined surface density. We therefore developed a quantitative E-cadherin surface immobilization protocol based on the SNAP-tag technique. Extracellular (EC fragments of E-cadherin fused to the SNAP-tag were covalently bound to self-assembled monolayers (SAM of thiols carrying benzylguanine (BG head groups. The adhesive functionality of the different E-cadherin surfaces was then assessed using cell spreading assays and single-cell (SCSF and single-molecule (SMSF force spectroscopy. We demonstrate that an E-cadherin construct containing only the first and second outmost EC domain (E1-2 is not sufficient for mediating cell adhesion and yields only low single cadherin-cadherin adhesion forces. In contrast, a construct containing all five EC domains (E1-5 efficiently promotes cell spreading and generates strong single cadherin and cell adhesion forces. By varying the concentration of BG head groups within the SAM we determined a lateral distance of 5-11 nm for optimal E-cadherin functionality. Integrating the results from SCMS and SMSF experiments furthermore demonstrated that the dissolution of E-cadherin adhesion contacts involves a sequential unbinding of individual cadherin receptors rather than the sudden rupture of larger cadherin receptor clusters. Our method of covalent, oriented and density-controlled E-cadherin immobilization thus provides a novel and versatile platform to study molecular mechanisms underlying cadherin-mediated cell adhesion under defined experimental conditions.

  8. Carbohydrate Coating Reduces Adhesion of Biofilm-Forming Bacillus subtilis to Gold Surfaces

    Science.gov (United States)

    Kesel, S.; Mader, A.; Seeberger, P. H.; Lieleg, O.

    2014-01-01

    The growth of bacterial biofilms in pipes and food tanks causes severe problems in industry. Biofilms growing on medical implants or catheters are of great concern, as they can cause serious infections and decrease the functionality of the medical device. The prevention of bacterial adhesion—the first step in colonization and biofilm formation—is therefore very important. Current research comprises alterations in surface properties, the prevention of adhesin biosynthesis, inhibition with receptor analogs, or the development of anti-adhesive vaccines. We present a new approach that allows us to study bacterial adhesion with high sensitivity in real-time while testing several different surfaces in parallel. Using the cantilever-array technique we demonstrate that coating of gold surfaces with mono- or disaccharides results in a reduction of the bacterial adhesion of the biofilm-forming bacterium Bacillus subtilis NCIB 3610 to these gold surfaces. This reduction in bacterial adhesion is independent of the studied carbohydrate. Using several mutant strains, we investigate the underlying molecular interactions, and our results suggest that adhesion to gold surfaces is mediated by thiol groups present in proteins of the bacterial cell membrane or biofilm matrix proteins expressed at low levels by the wild-type strain. Furthermore, our data indicate that the adhesion of B. subtilis NCIB 3610 to carbohydrate-coated gold surfaces is facilitated by interactions between carbohydrates installed on the cantilever gold surface and an exopolysaccharide expressed by this strain. Understanding general and specific contributions of molecular interactions mediating bacterial adhesion will enable its prevention in the future. PMID:25038098

  9. Fabrication of Superhydrophobic Surfaces with Controllable Electrical Conductivity and Water Adhesion.

    Science.gov (United States)

    Ye, Lijun; Guan, Jipeng; Li, Zhixiang; Zhao, Jingxin; Ye, Cuicui; You, Jichun; Li, Yongjin

    2017-02-14

    A facile and versatile strategy for fabricating superhydrophobic surfaces with controllable electrical conductivity and water adhesion is reported. "Vine-on-fence"-structured and cerebral cortex-like superhydrophobic surfaces are constructed by filtering a suspension of multiwalled carbon nanotubes (MWCNTs), using polyoxymethylene nonwovens as the filter paper. The nonwovens with micro- and nanoporous two-tier structures act as the skeleton, introducing a microscale structure. The MWCNTs act as nanoscale structures, creating hierarchical surface roughness. The surface topography and the electrical conductivity of the superhydrophobic surfaces are controlled by varying the MWCNT loading. The vine-on-fence-structured surfaces exhibit "sticky" superhydrophobicity with high water adhesion. The cerebral cortex-like surfaces exhibit self-cleaning properties with low water adhesion. The as-prepared superhydrophobic surfaces are chemically resistant to acidic and alkaline environments of pH 2-12. They therefore have potential in applications such as droplet-based microreactors and thin-film microextraction. These findings aid our understanding of the role that surface topography plays in the design and fabrication of superhydrophobic surfaces with different water-adhesion properties.

  10. Surface modification and adhesion improvement of PTFE film by ion beam irradiation

    International Nuclear Information System (INIS)

    Lee, S.W.; Hong, J.W.; Wye, M.Y.; Kim, J.H.; Kang, H.J.; Lee, Y.S.

    2004-01-01

    The polytetrafluoroethylene (PTFE) surfaces, modified by 1 kV Ar + or O 2 + ion beam irradiation, was investigated with in-situ X-ray photoelectron spectroscopy (XPS), scanning electron micrographs (SEM), atomic force microscopy (AFM) measurements. The surface of PTFE films modified by Ar + ion irradiation was carbonized and the surface roughness increased with increasing ion doses. The surface of PTFE films modified by both Ar + ion in O 2 atmosphere and O 2 + ion irradiation formed the oxygen function group on PTFE surface, and the surface roughness change was relatively small. The adhesion improvement in Ar + ion irradiated PTFE surface is attributed to mechanical interlocking due to the surface roughness and -CF-radical, but that in Ar + ion irradiation in an O 2 atmosphere was contributed by the C-O complex and -CF-radical with mechanical interlocking. The C-O complex and -CF-radical in O 2 + ion irradiated surface contributed to the adhesion

  11. Bottom-up engineering of the surface roughness of nanostructured cubic zirconia to control cell adhesion

    International Nuclear Information System (INIS)

    Singh, A V; Ferri, M; Tamplenizza, M; Borghi, F; Lenardi, C; Piazzoni, C; Podestà, A; Milani, P; Divitini, G; Ducati, C; Merlini, M

    2012-01-01

    Nanostructured cubic zirconia is a strategic material for biomedical applications since it combines superior structural and optical properties with a nanoscale morphology able to control cell adhesion and proliferation. We produced nanostructured cubic zirconia thin films at room temperature by supersonic cluster beam deposition of nanoparticles produced in the gas phase. Precise control of film roughness at the nanoscale is obtained by operating in a ballistic deposition regime. This allows one to study the influence of nanoroughness on cell adhesion, while keeping the surface chemistry constant. We evaluated cell adhesion on nanostructured zirconia with an osteoblast-like cell line using confocal laser scanning microscopy for detailed morphological and cytoskeleton studies. We demonstrated that the organization of cytoskeleton and focal adhesion formation can be controlled by varying the evolution of surface nanoroughness. (paper)

  12. 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.

  13. A probabilistic approach to measure the strength of bone cell adhesion to chemically modified surfaces.

    Science.gov (United States)

    Rezania, A; Thomas, C H; Healy, K E

    1997-01-01

    Patterned surfaces with alternating regions of amino silanes [N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (EDS)] and alkyl silanes [dimethyldichlorosilane (DMS)] have been used to alter the kinetics of spatial distribution of cells in vitro. In particular, we have previously observed the preferential spatial distribution of bone cells on the EDS regions of EDS/ DMS patterned surfaces (10). In this study, we examined whether the mechanism of spatial distribution of cells on the EDS regions was adhesion mediated. Homogeneous layers of EDS and DMS were immobilized on quartz substrates and characterized by contact angle. X-ray photoelectron spectroscopy, and spectroscopic ellipsometry. The strength of bone cell attachment to the modified substrates was examined using a radial flow apparatus, within either 20 min or 2 hr of cell incubation in the presence of serum. A Weibull distribution was chosen to characterize the strength of cell-substratum adhesion. Within 20 min of cell exposure, the strength of adhesion was significantly larger on EDS and clean surfaces, compared with DMS surfaces (p < 0.001). Within 2 hr of cell incubation, there was no statistical difference between the strength of cell adhesion to EDS, DMS, and clean surfaces. The results of this study suggest that the surface chemistry mediates adhesion-based spatial cell arrangement through a layer of adsorbed serum proteins.

  14. Biomimetic surface modification of polypropylene by surface chain transfer reaction based on mussel-inspired adhesion technology and thiol chemistry

    International Nuclear Information System (INIS)

    Niu, Zhijun; Zhao, Yang; Sun, Wei; Shi, Suqing; Gong, Yongkuan

    2016-01-01

    Highlights: • Biomimetic surface modification of PP was successfully conducted by integrating mussel-inspired technology, thiol chemistry and cell outer membranes-like structures. • The resultant biomimetic surface exhibits good interface and surface stability. • The obvious suppression of protein adsorption and platelet adhesion is also achieved. • The residue thoil groups on the surface could be further functionalized. - Abstract: Biomimetic surface modification of polypropylene (PP) is conducted by surface chain transfer reaction based on the mussel-inspired versatile adhesion technology and thiol chemistry, using 2-methacryloyloxyethylphosphorylcholine (MPC) as a hydrophilic monomer mimicking the cell outer membrane structure and 2,2-azobisisobutyronitrile (AIBN) as initiator in ethanol. A layer of polydopamine (PDA) is firstly deposited onto PP surface, which not only offers good interfacial adhesion with PP, but also supplies secondary reaction sites (-NH 2 ) to covalently anchor thiol groups onto PP surface. Then the radical chain transfer to surface-bonded thiol groups and surface re-initiated polymerization of MPC lead to the formation of a thin layer of polymer brush (PMPC) with cell outer membrane mimetic structure on PP surface. X-ray photoelectron spectrophotometer (XPS), atomic force microscopy (AFM) and water contact angle measurements are used to characterize the PP surfaces before and after modification. The protein adsorption and platelet adhesion experiments are also employed to evaluate the interactions of PP surface with biomolecules. The results show that PMPC is successfully grafted onto PP surface. In comparison with bare PP, the resultant PP-PMPC surface exhibits greatly improved protein and platelet resistance performance, which is the contribution of both increased surface hydrophilicity and zwitterionic structure. More importantly, the residue thiol groups on PP-PMPC surface create a new pathway to further functionalize such

  15. Biomimetic surface modification of polypropylene by surface chain transfer reaction based on mussel-inspired adhesion technology and thiol chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Zhijun; Zhao, Yang; Sun, Wei; Shi, Suqing, E-mail: shisq@nwu.edu.cn; Gong, Yongkuan

    2016-11-15

    Highlights: • Biomimetic surface modification of PP was successfully conducted by integrating mussel-inspired technology, thiol chemistry and cell outer membranes-like structures. • The resultant biomimetic surface exhibits good interface and surface stability. • The obvious suppression of protein adsorption and platelet adhesion is also achieved. • The residue thoil groups on the surface could be further functionalized. - Abstract: Biomimetic surface modification of polypropylene (PP) is conducted by surface chain transfer reaction based on the mussel-inspired versatile adhesion technology and thiol chemistry, using 2-methacryloyloxyethylphosphorylcholine (MPC) as a hydrophilic monomer mimicking the cell outer membrane structure and 2,2-azobisisobutyronitrile (AIBN) as initiator in ethanol. A layer of polydopamine (PDA) is firstly deposited onto PP surface, which not only offers good interfacial adhesion with PP, but also supplies secondary reaction sites (-NH{sub 2}) to covalently anchor thiol groups onto PP surface. Then the radical chain transfer to surface-bonded thiol groups and surface re-initiated polymerization of MPC lead to the formation of a thin layer of polymer brush (PMPC) with cell outer membrane mimetic structure on PP surface. X-ray photoelectron spectrophotometer (XPS), atomic force microscopy (AFM) and water contact angle measurements are used to characterize the PP surfaces before and after modification. The protein adsorption and platelet adhesion experiments are also employed to evaluate the interactions of PP surface with biomolecules. The results show that PMPC is successfully grafted onto PP surface. In comparison with bare PP, the resultant PP-PMPC surface exhibits greatly improved protein and platelet resistance performance, which is the contribution of both increased surface hydrophilicity and zwitterionic structure. More importantly, the residue thiol groups on PP-PMPC surface create a new pathway to further functionalize such

  16. Modeling and design optimization of adhesion between surfaces at the microscale.

    Energy Technology Data Exchange (ETDEWEB)

    Sylves, Kevin T. (University of Colorado, Boulder, CO)

    2008-08-01

    This research applies design optimization techniques to structures in adhesive contact where the dominant adhesive mechanism is the van der Waals force. Interface finite elements are developed for domains discretized by beam elements, quadrilateral elements or triangular shell elements. Example analysis problems comparing finite element results to analytical solutions are presented. These examples are then optimized, where the objective is matching a force-displacement relationship and the optimization variables are the interface element energy of adhesion or the width of beam elements in the structure. Several parameter studies are conducted and discussed.

  17. [Effects of Nd: YAG laser irradiation on the root surfaces and adhesion of Streptococcus mutans].

    Science.gov (United States)

    Yuanhong, Li; Zhongcheng, Li; Mengqi, Luo; Daonan, Shen; Shu, Zhang; Shu, Meng

    2016-12-01

    This study aimed to evaluate the effects of treatment with different powers of Nd: YAG laser irradiation on root surfaces and Streptococcus mutans (S. mutans) adhesion. Extracted teeth because of severe periodontal disease were divided into the following four groups: control group, laser group 1, laser group 2, and laser group 3. After scaling and root planning, laser group 1, laser group 2, and laser group 3 were separately treated with Nd: YAG laser irradiation (4/6/8 W, 60 s); however, the control group did not receive the treatment. Scanning electron microscopy (SEM) was used to determine the morphology. S. mutans were cultured with root slices from each group. Colony forming unit per mL (CFU·mL⁻¹) was used to count and compare the amounts of bacteria adhesion among groups. SEM was used to observe the difference of bacteria adhesion to root surfaces between control group (scaling) and laser group 2 (6 W, 60 s), thereby indicating the different bacteria adhesions because of different treatments. Morphology alterations indicated that root surfaces in control group contain obvious smear layer, debris, and biofilm; whereas the root surfaces in laser group contain more cracks with less smear layer and debris. The bacteria counting indicated that S. mutans adhesion to laser group was weaker than that of control group (P0.05) was observed. Morphology alterations also verified that S. mutans adhesion to laser group 2 (6 W, 60 s) was weaker than that of control group (scaling). This study demonstrated that Nd: YAG laser irradiation treatment after scaling can reduce smear layer, debris, and biofilm on the root surfaces as compared with conventional scaling. The laser treatment reduces the adhesion of S. mutans as well. However, Nd: YAG laser irradiation can cause cracks on the root surfaces. In this experiment, the optimum laser power of 6 W can thoroughly remove the smear layer and debris, as well as relatively improve the control of thermal damagee.

  18. Asperity interaction in elastic-plastic contact of rough surfaces in presence of adhesion

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Banerjee, Atanu

    2005-01-01

    This paper presents an analysis of the effect of asperity interaction in elastic-plastic contact of rough surfaces in the presence of adhesion. The micro-contact model of asperity interactions, developed by Zhao and Chang (2001 Trans. ASME: J. Tribol. 123 857-64), is integrated into the elastic-plastic contact model developed by Roy Chowdhury and Ghosh (1994 Wear 174 9-19) to allow the asperity interaction and elastic-plastic deformation in the presence of surface forces to be considered simultaneously. The well-established elastic and plastic adhesion indices are used to consider the different conditions that arise as a result of varying load and material parameters. Results show that asperity interaction influences the loading-unloading behaviour in elastic-plastic adhesive contact of rough surfaces and in general asperity interactions reduce the effect of surface forces

  19. Adhesion of Pathogenic Bacteria to Food Contact Surfaces: Influence of pH of Culture

    Directory of Open Access Journals (Sweden)

    Akier Assanta Mafu

    2011-01-01

    Full Text Available The adhesion of Aeromonas hydrophila, Escherichia coli O157:H7, Salmonella Enteritidis, and Staphylococcus aureus to hydrophobic and hydrophilic surfaces in cultures with different pHs (6, 7, and 8 was studied. The results indicated that the type of material had no effect on the attachment capacity of microorganisms, while environmental pH influenced the adhesion of A. hydrophila, E. coli, and S. aureus to both solid substrates. The attachment of S. Enteritidis (P>.05 was not affected by the type of substrate or the culture pH, whereas E. coli displayed the weakest affinity for both polystyrene and glass surfaces. No correlation was established between the physicochemical properties of the materials, or the bacterial and the rate of bacterial adhesion, except for S. aureus. Photomicrographs have shown that surfaces were contaminated by small clusters of S. Enteritidis while S. aureus invaded the food contact surfaces in the form of small chains or cell aggregates.

  20. Atmospheric-Pressure Plasma Jet Surface Treatment for Use in Improving Adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Kuettner, Lindsey Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-06

    Atmospheric-pressure plasma jets (APPJs) are a method of plasma treatment that plays an important role in material processing and modifying surface properties of materials, especially polymers. Gas plasmas react with polymer surfaces in numerous ways such as oxidation, radical formation, degradation, and promotion of cross-linking. Because of this, gas and plasma conditions can be explored for chosen processes to maximize desired properties. The purpose of this study is to investigate plasma parameters in order to modify surface properties for improved adhesion between aluminum and epoxy substrates using two types of adhesives. The background, results to date, and future work will be discussed.

  1. Adhesion and friction of polymer surfaces studied using scanning probe microscopy

    Science.gov (United States)

    Moon, Seung-Ho

    2003-10-01

    Scanning Probe Microscopy has been utilized to investigate the nanomechanical and nanorheological properties at the surface of polymers and polymer blends. To study the surface behavior in detail, it is critical that the SPM instrument have sufficient flexibility. A temperature stage and environmental chamber have been implemented and measurement automation has been achieved using a high-speed data acquisition system controlled by LabView(TM). Finally, new measurement protocols, "X-modulation" and "Force-Distance with X-modulation", have been developed. First measurements using those techniques have been performed for the study of aged model pressure sensitive adhesives. It has been found that the magnitude of the lateral force is so sensitive to adhesion force that X-modulation can identify qualitative differences in the strength of surface stickiness. Variations in surface adhesiveness with humidity are more obvious when the tackifier is present. A large lateral force and strongly reduced stiffness, measured using F-d with X-modulation, have been observed at high humidity for the homogeneous, hydrophilic surface of the adhesive loaded with 60wt% tackifier. These observations are consistent with a model that envisions a tackifier-enriched region near the surface. A large creep effect has also been observed for this sample, and the creep effect is magnified with temperature. These results are consistent with the hypothesis that at a hydrophilic adhesive surface water molecules may strongly alter the surface-tip interactions or modify the mechanical properties of the material nearest the surface. By changing the Z-loading velocity, dynamic adhesion behavior has been investigated. The mechanism of adhesive failure have been elucidated by comparing the velocity dependence of pull-off force and lateral force. Since this dynamic measurement is sensitive to the material composition at the surface, it has been utilized to study the surface segregation of one component at

  2. Influence of Surface Roughness of Stainless steel on Microbial Adhesion

    DEFF Research Database (Denmark)

    Bagge, D.; Hilbert, Lisbeth Rischel; Gram, L.

    2002-01-01

    status of the surface; it is assumed that microorganisms hide in scratches and cracks. It is also believed that the smoother a surface the better. And a surface with a few microorganisms after cleaning and disinfection is more hygienic and has a lower risk for cross contamination than a surface with many...

  3. Controlling the Adhesion of Superhydrophobic Surfaces Using Electrolyte Jet Machining Techniques.

    Science.gov (United States)

    Yang, Xiaolong; Liu, Xin; Lu, Yao; Zhou, Shining; Gao, Mingqian; Song, Jinlong; Xu, Wenji

    2016-04-05

    Patterns with controllable adhesion on superhydrophobic areas have various biomedical and chemical applications. Electrolyte jet machining technique (EJM), an electrochemical machining method, was firstly exploited in constructing dimples with various profiles on the superhydrophobic Al alloy surface using different processing parameters. Sliding angles of water droplets on those dimples firstly increased and then stabilized at a certain value with the increase of the processing time or the applied voltages of the EJM, indicating that surfaces with different adhesion force could be obtained by regulating the processing parameters. The contact angle hysteresis and the adhesion force that restricts the droplet from sliding off were investigated through experiments. The results show that the adhesion force could be well described using the classical Furmidge equation. On account of this controllable adhesion force, water droplets could either be firmly pinned to the surface, forming various patterns or slide off at designed tilting angles at specified positions on a superhydrophobic surface. Such dimples on superhydrophopbic surfaces can be applied in water harvesting, biochemical analysis and lab-on-chip devices.

  4. Controlling the Adhesion of Superhydrophobic Surfaces Using Electrolyte Jet Machining Techniques

    Science.gov (United States)

    Yang, Xiaolong; Liu, Xin; Lu, Yao; Zhou, Shining; Gao, Mingqian; Song, Jinlong; Xu, Wenji

    2016-01-01

    Patterns with controllable adhesion on superhydrophobic areas have various biomedical and chemical applications. Electrolyte jet machining technique (EJM), an electrochemical machining method, was firstly exploited in constructing dimples with various profiles on the superhydrophobic Al alloy surface using different processing parameters. Sliding angles of water droplets on those dimples firstly increased and then stabilized at a certain value with the increase of the processing time or the applied voltages of the EJM, indicating that surfaces with different adhesion force could be obtained by regulating the processing parameters. The contact angle hysteresis and the adhesion force that restricts the droplet from sliding off were investigated through experiments. The results show that the adhesion force could be well described using the classical Furmidge equation. On account of this controllable adhesion force, water droplets could either be firmly pinned to the surface, forming various patterns or slide off at designed tilting angles at specified positions on a superhydrophobic surface. Such dimples on superhydrophopbic surfaces can be applied in water harvesting, biochemical analysis and lab-on-chip devices. PMID:27046771

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  6. The effect of poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners.

    Science.gov (United States)

    Cavalcanti, Yuri Wanderley; Bertolini, Martinna Mendonça; Cury, Altair Antoninha Del Bel; da Silva, Wander José

    2014-12-01

    Different surface treatment protocols of poly(methyl methacrylate) have been proposed to improve the adhesion of silicone-based resilient denture liners to poly(methyl methacrylate) surfaces. The purpose of this study was to evaluate the effect of different poly(methyl methacrylate) surface treatments on the adhesion of silicone-based resilient denture liners. Poly(methyl methacrylate) specimens were prepared and divided into 4 treatment groups: no treatment (control), methyl methacrylate for 180 seconds, acetone for 30 seconds, and ethyl acetate for 60 seconds. Poly(methyl methacrylate) disks (30.0 × 5.0 mm; n = 10) were evaluated regarding surface roughness and surface free energy. To evaluate tensile bond strength, the resilient material was applied between 2 treated poly(methyl methacrylate) bars (60.0 × 5.0 × 5.0 mm; n = 20 for each group) to form a 2-mm-thick layer. Data were analyzed by 1-way ANOVA and the Tukey honestly significant difference tests (α = .05). A Pearson correlation test verified the influence of surface properties on tensile bond strength. Failure type was assessed, and the poly(methyl methacrylate) surface treatment modifications were visualized with scanning electron microscopy. The surface roughness was increased (P denture liner to poly(methyl methacrylate). Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  7. Impact of ionic strength of growth on the physiochemical properties, structure, and adhesion of Listeria monocytogenes polyelectrolyte brushes to a silicon nitride surface in water.

    Science.gov (United States)

    Gordesli, Fatma Pinar; Abu-Lail, Nehal I

    2012-12-15

    The adhesion energies between pathogenic Listeria monocytogenes EGDe to a model surface of silicon nitride were quantified using atomic force microscopy (AFM) in water for cells grown in pure media (as the control) and in media of four different ionic strengths of added NaCl (IS of 0.05 M, 0.1 M, 0.3 M and 0.5 M NaCl). The physiochemical properties of L. monocytogenes EGDe surface brushes were shown to have a strong influence on the adhesion of the microbe to the silicon nitride surface. The transitions in the adhesion energies, physiochemical properties, and the structure of bacterial surface polyelectrolyte brushes were observed for the cells grown in the media of 0.1M added NaCl. Our results suggested that the highest long-range electrostatic repulsion which was partially balanced by the Liftshitz-van der Waals attraction for the cells grown at 0.1M was responsible for the highest energy barrier to adhesion for these cells as predicted by the soft-particle analysis of DLVO theory and the lower adhesion measured by AFM. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Increased adhesion of polydimethylsiloxane (PDMS) to acrylic adhesive tape for medical use by surface treatment with an atmospheric pressure rotating plasma jet

    Science.gov (United States)

    Jofre-Reche, José Antonio; Pulpytel, Jérôme; Arefi-Khonsari, Farzaneh; Martín-Martínez, José Miguel

    2016-08-01

    The surface properties of polydimethylsiloxane (PDMS) were modified by treatment with an atmospheric pressure rotating plasma jet (APPJ) and the surface modifications were studied to assess its hydrophilicity and adhesion to acrylic adhesive tape intended for medical applications. Furthermore, the extent of hydrophobic recovery under different storage conditions was studied. The surface treatment of PDMS with the APPJ under optimal conditions noticeably increased the oxygen content and most of the surface silicon species were fully oxidized. A brittle silica-like layer on the outermost surface was created showing changes in topography due to the formation of grooves and cracks. A huge improvement in T-peel and the shear adhesive strength of the APPJ-treated PDMS surface/acrylic tape joints was obtained. On the other hand, the hydrophilicity of the PDMS surface increased noticeably after the APPJ treatment, but 24 h after treatment almost 80% hydrophobicity was recovered and the adhesive strength was markedly reduced with time after the APPJ treatment. However, the application of an acrylic adhesive layer on the just-APPJ-treated PDMS surface retained the adhesive strength, limiting the extent of hydrophobic recovery.

  9. Increased adhesion of polydimethylsiloxane (PDMS) to acrylic adhesive tape for medical use by surface treatment with an atmospheric pressure rotating plasma jet

    International Nuclear Information System (INIS)

    Jofre-Reche, José Antonio; Martín-Martínez, José Miguel; Pulpytel, Jérôme; Arefi-Khonsari, Farzaneh

    2016-01-01

    The surface properties of polydimethylsiloxane (PDMS) were modified by treatment with an atmospheric pressure rotating plasma jet (APPJ) and the surface modifications were studied to assess its hydrophilicity and adhesion to acrylic adhesive tape intended for medical applications. Furthermore, the extent of hydrophobic recovery under different storage conditions was studied. The surface treatment of PDMS with the APPJ under optimal conditions noticeably increased the oxygen content and most of the surface silicon species were fully oxidized. A brittle silica-like layer on the outermost surface was created showing changes in topography due to the formation of grooves and cracks. A huge improvement in T-peel and the shear adhesive strength of the APPJ-treated PDMS surface/acrylic tape joints was obtained. On the other hand, the hydrophilicity of the PDMS surface increased noticeably after the APPJ treatment, but 24 h after treatment almost 80% hydrophobicity was recovered and the adhesive strength was markedly reduced with time after the APPJ treatment. However, the application of an acrylic adhesive layer on the just-APPJ-treated PDMS surface retained the adhesive strength, limiting the extent of hydrophobic recovery. (paper)

  10. Atmospheric pressure plasma surface modification of titanium for high temperature adhesive bonding

    NARCIS (Netherlands)

    Akram, M.; Jansen, K.M.B.; Ernst, L.J.; Bhowmik, S.

    2011-01-01

    In this investigation surface treatment of titanium is carried out by plasma ion implantation under atmospheric pressure plasma in order to increase the adhesive bond strength. Prior to the plasma treatment, titanium surfaces were mechanically treated by sand blasting. It is observed that the

  11. 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

    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

  12. Surface thermodynamics and adhesion forces governing bacterial transmission in contact lens related microbial keratitis

    NARCIS (Netherlands)

    Qu, Wenwen; Busscher, Henk J.; Hooymans, Johanna M. M.; van der Mei, Henny C.

    2011-01-01

    Contact lens induced microbial keratitis results from bacterial transmission from one surface to another. We investigated the adhesion forces of Pseudomonas aeruginosa, Staphylococci and Serratia to different contact lenses, lens cases and corneal surfaces using AFM, and applied a Weibull analysis

  13. Elastic–plastic adhesive contact of non-Gaussian rough surfaces

    Indian Academy of Sciences (India)

    on friction and wear of contacting surfaces. A great deal of progress has been made in this aspect both experimentally and analytically. Some of the pioneering work includes that of. Bowden & Rowe (1956), which shows the importance of surface film and released elastic stresses in reducing adhesion. When the smooth ...

  14. Methods for surface treating metals, ceramics, and plastics before adhesive bonding

    International Nuclear Information System (INIS)

    Althouse, L.P.

    1976-01-01

    Methods for pretreating the surfaces of metals, ceramics, and plastics before they are coated with adhesive and used in assembly are described. The treatments recommended have been used successfully in the laboratory at LLL. Many are used in the assembly of nuclear devices. However, an unusual alloy or complex configuration may require trials before a specific surface treatment is chosen

  15. Adhesion of resin composites to biomaterials in dentistry : an evaluation of surface conditioning methods

    NARCIS (Netherlands)

    Özcan, Mutlu

    2003-01-01

    Since previous investigations revealed that most clinical failures in adhesively luted ceramic restorations initiate from the cementation or internal surfaces, the study presented in Chapter II evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA

  16. Adhesion of coagulase-negative staphylococci grouped according to physico-chemical surface properties

    NARCIS (Netherlands)

    van der Mei, HC; van de Belt-Gritter, B; Reid, G; Bialkowska-Hobrzanska, H; Busscher, HJ

    1997-01-01

    Physico-chemical cell surface properties of 23 coagulase-negative staphylococcal strains, including contact angles, zeta potentials and elemental cell surface composition were measured, together with the adhesion of all strains to hexadecane, The data were employed in a hierarchical cluster

  17. Silane adhesion mechanism in dental applications and surface treatments: A review.

    Science.gov (United States)

    Matinlinna, Jukka Pekka; Lung, Christie Ying Kei; Tsoi, James Kit Hon

    2018-01-01

    To give a current review of silane adhesion chemistry, applications of silane coupling agents and related surface pretreatment methods in contemporary dentistry. Silane coupling agents are adhesion promoters to chemically unify dissimilar materials used in dentistry. Silanes are very effective in adhesion promotion between resin composites and silica-based or silica-coated indirect restorative materials. It is generally accepted that for non-silica-based restorations, surface pretreatment is a mandatory preliminary step to increase the silica content and then, with help of silane, improve resin bonding. This review discusses the silane-based adhesion chemistry, silane applications in dentistry, surface pretreatment methods, and presents the recent development of silane coupling agents. A silane coupling agent is considered a reliable, good adhesion promoter to silica-based (or silica-coated) indirect restorations. Surface pre-treatment steps, e.g., acid etching for porcelain and tribo-chemical silica-coating for metal alloys, is used before silanization to attain strong, durable bonding of the substrate to resin composite. In clinical practice, however, the main problem of resin bonding using silanes and other coupling agents is the weakening of the bond (degradation) in the wet oral environment over time. A silane coupling agent is a justified and popular adhesion promoter (adhesive primer) used in dentistry. The commercial available silane coupling agents can fulfil the requirements in clinical practice for durable bonding. Development of new silane coupling agents, their optimization, and surface treatment methods are in progress to address the long term resin bond durability and are highly important. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. The effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base material.

    Science.gov (United States)

    Yodmongkol, Sirasa; Chantarachindawong, Rojcharin; Thaweboon, Sroisiri; Thaweboon, Boonyanit; Amornsakchai, Taweechai; Srikhirin, Toemsak

    2014-12-01

    Polysiloxane has been used as a coupling material in restorative dental materials for several decades. However, few studies are available on the application of polysiloxane in other dental prosthesis functions. The purpose of this study was to investigate the effects of silane-SiO2 nanocomposite films on Candida albicans adhesion and the surface and physical properties of acrylic resin denture base materials. Specimens were separated into 2 groups, uncoated and coated. They were coated with a film by using the dip-coating method. Specimens were incubated with Candida albicans 10(7) cells/mL for 1 hour, and the adherent cells were counted under an optical microscope. The following surface properties were measured: surface chemical composition with Fourier-transform infrared spectrometry, surface roughness with a surface profiler, surface energy with the sessile drop method, and surface hardness with a microhardness tester. The physical properties, including water sorption, water solubility, ultimate flexural strength, and flexural modulus, were evaluated according to International Organization for Standardization 20795-1 requirements. The adhesion of Candida albicans and the surface properties of the specimens were investigated after cleaning with effervescent tablets and brushing. An MTT assay was used to evaluate the coated specimens. The results were statistically analyzed with the Mann-Whitney U test (α=.05). A significant reduction in Candida albicans adhesion (P=.002) was observed before cleaning. In addition, the surface energy was comparable (P=.100), the surface hardness increased significantly (P=.008), and the surface roughness remained unchanged (P=.310). After cleaning with effervescent tablets, a significant decrease in Candida albicans adhesion (P=.002) and in surface roughness (P=.008) was observed; however, similar surface energies were measured (P=.100). After cleaning with a toothbrush, the adhesion of Candida albicans was significantly higher on

  19. Roles of acidic functional groups of carbon fiber surfaces in enhancing interfacial adhesion behavior

    International Nuclear Information System (INIS)

    Park, Soo-Jin; Kim, Byung-Joo

    2005-01-01

    The gas phase ozone treatment was used as a method to bind acidic oxygen functional groups on carbon fiber surfaces. The ozone treatment on carbon fibers was varied with the ozone concentration and treatment time. Surface analyses of the carbon fibers before and after treatments were performed by FT-IR, X-ray photoelectron spectrometer (XPS), and dynamic contact angle measurements. Mechanical interfacial properties of the fibers/polymer composites were investigated by using critical stress intensity factor (K IC ) and critical energy release rate (G IC ) measurements. From the results of FT-IR and XPS, it was observed that the oxygen functional groups, such as -OH, O-C=O, C=O, and C-O, were attached on the carbon fiber surfaces after the ozone treatment. The mechanical interfacial properties of the composites also showed higher values than those of untreated composites. Ozone treatment is attributed to the increase of both the acidic functional groups and the degree of adhesion at interfaces between the fibers and polymeric resin in composites

  20. High efficient and continuous surface modification of carbon fibers with improved tensile strength and interfacial adhesion

    Science.gov (United States)

    Sun, Jingfeng; Zhao, Feng; Yao, Yue; Jin, Zhen; Liu, Xu; Huang, Yudong

    2017-08-01

    Most of the surface modification technologies for carbon fibers, no matter in laboratory scale or for commercial manufacture, are accompanied by a simultaneous decrease in tensile strength. In this paper, a feasible and high efficient strategy for carbon fiber treatment which could obviously improve both tensile strength and interfacial adhesion was proposed. Continuously moving carbon fibers were treated with atmospheric helium plasma for 1 min, followed by a 5 min pyrolytic carbon deposition using ethanol as precursor at 800 °C. The effects of the new approach were characterized by SEM, AFM, nanoindentation, XPS, Raman, wettability analysis, single fiber tensile strength testing and single fiber pull-out testing. After modification, pyrolytic carbon coating was deposited on the fiber surface uniformly, and the roughness and surface energy increased significantly. The single fiber tensile testing results indicate that the resulting fiber strength increased 15.7%, rising from 3.13 to 3.62 GPa. Meanwhile, the interfacial shear strength of its epoxy composites increased from 65.3 to 83.5 MPa. The comparative studies of carbon fibers modified with commercial anodic oxidation and sizing were also carried out. The results demonstrate that the new method can be utilized in the carbon fiber manufacture process and is more efficient than the traditional approaches.

  1. Surface energy of explosive nanoparticles

    Science.gov (United States)

    Pineau, Nicolas; Bidault, Xavier; Soulard, Laurent

    2017-06-01

    Recent experimental studies show that nanostructuration has a substantial impact on the detonation of high explosives: a nanostructured one leads to smaller nanodiamonds than a microstructured one. Whether it comes from a higher surface energy or from porosity, the origin of these different behaviors must be investigated. The surface energy of TATB nanoparticles with a radius from 2 nm upto 60 nm has been determined by means of ReaxFF-based simulations. Then, using the Rankine-Hugoniot relations and the equation of states of the bulk material, the contribution of this excess energy to the heating of a shock-compressed nanostructured (and porous) material is evaluated and compared to the thermal effect due to its porosity collapse. A maximum temperature increase of 50 K is found for 4-nm nanoparticles, which remains negligible when compared to the few hundred degrees induced by the compaction work.

  2. Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

    Energy Technology Data Exchange (ETDEWEB)

    Latifi, Afrooz, E-mail: afroozlatifi@yahoo.com [Department of Biomaterials, Biomedical Engineering Faculty, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Imani, Mohammad [Novel Drug Delivery Systems Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/115, Tehran (Iran, Islamic Republic of); Khorasani, Mohammad Taghi [Biomaterials Dept., Iran Polymer and Petrochemical Institute, P.O. Box 14965/159, Tehran (Iran, Islamic Republic of); Daliri Joupari, Morteza [Animal and Marine Biotechnology Dept., National Institute of Genetic Engineering and Biotechnology, P.O. Box 14965/161, Tehran (Iran, Islamic Republic of)

    2014-11-30

    Highlights: • Stainless steel 316L was surface modified by plasma surface oxidation (PSO) and silicone rubber (SR) coating. • On the PSO substrates, concentration of oxide species was increased ca. 2.5 times comparing to non-PSO substrates. • The surface wettability was improved to 12.5°, in terms of water contact angle, after PSO. • Adhesion strength of SR coating on the PSO substrates was improved by more than two times comparing to non-PSO ones. • After pull-off test, the fractured area patterns for SR coating were dependent on the type of surface modifications received. - Abstract: Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m{sup −1}), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer–metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

  3. On the nature of surface roughness with application to contact mechanics, sealing, rubber friction and adhesion

    International Nuclear Information System (INIS)

    Persson, B N J; Albohr, O; Tartaglino, U; Volokitin, A I; Tosatti, E

    2005-01-01

    Surface roughness has a huge impact on many important phenomena. The most important property of rough surfaces is the surface roughness power spectrum C(q). We present surface roughness power spectra of many surfaces of practical importance, obtained from the surface height profile measured using optical methods and the atomic force microscope. We show how the power spectrum determines the contact area between two solids. We also present applications to sealing, rubber friction and adhesion for rough surfaces, where the power spectrum enters as an important input. (topical review)

  4. Atomic force microscopy studies of bioprocess engineering surfaces - imaging, interactions and mechanical properties mediating bacterial adhesion.

    Science.gov (United States)

    James, Sean A; Hilal, Nidal; Wright, Chris J

    2017-07-01

    The detrimental effect of bacterial biofilms on process engineering surfaces is well documented. Thus, interest in the early stages of bacterial biofilm formation; in particular bacterial adhesion and the production of anti-fouling coatings has grown exponentially as a field. During this time, Atomic force microscopy (AFM) has emerged as a critical tool for the evaluation of bacterial adhesion. Due to its versatility AFM offers not only insight into the topographical landscape and mechanical properties of the engineering surfaces, but elucidates, through direct quantification the topographical and biomechnical properties of the foulants The aim of this review is to collate the current research on bacterial adhesion, both theoretical and practical, and outline how AFM as a technique is uniquely equipped to provide further insight into the nanoscale world at the bioprocess engineering surface. Copyright © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Adhesion defective BHK cell mutant has cell surface heparan sulfate proteoglycan of altered properties

    DEFF Research Database (Denmark)

    Couchman, J R; Austria, R; Woods, A

    1988-01-01

    In the light of accumulating data that implicate cell surface heparan sulfate proteoglycans (HSPGs) with a role in cell interactions with extracellular matrix molecules such as fibronectin, we have compared the properties of these molecules in wild-type BHK cells and an adhesion-defective ricin......-resistant mutant (RicR14). Our results showed that the mutant, unlike BHK cells, cannot form focal adhesions when adherent to planar substrates in the presence of serum. Furthermore, while both cell lines possess similar amounts of cell surface HSPG with hydrophobic properties, that of RicR14 cells had decreased...... sulfation, reduced affinity for fibronectin and decreased half-life on the cell surface when compared to the normal counterpart. Our conclusions based on this data are that these altered properties may, in part, account for the adhesion defect in the ricin-resistant mutant. Whether this results from...

  6. Nanocrystalline diamond surfaces for adhesion and growth of primary neurons, conflicting results and rational explanation

    Directory of Open Access Journals (Sweden)

    Silviya Mikhailovna Ojovan

    2014-06-01

    Full Text Available Using a variety of proliferating cell types, it was shown that the surface of nanocrystalline-diamond (NCD provides a permissive substrate for cell adhesion and development without the need of complex chemical functionalization prior to cell seeding. In an extensive series of experiments we found that, unlike proliferating cells, post-mitotic primary neurons do not adhere to bare NCD surfaces when cultured in defined medium. These observations raise questions on the potential use of bare NCD as an interfacing layer for neuronal devices. Nevertheless, we also found that classical chemical functionalization methods render the hostile bare NCD surfaces with adhesive properties that match those of classically functionalized substrates used extensively in biomedical research and applications. Based on the results, we propose a mechanism that accounts for the conflicting results; which on one hand claim that un-functionalized NCD provides a permissive substrate for cell adhesion and growth, while other reports demonstrate the opposite.

  7. Programming controlled adhesion of E. coli to target surfaces, cells, and tumors with synthetic adhesins.

    Science.gov (United States)

    Piñero-Lambea, Carlos; Bodelón, Gustavo; Fernández-Periáñez, Rodrigo; Cuesta, Angel M; Álvarez-Vallina, Luis; Fernández, Luis Ángel

    2015-04-17

    In this work we report synthetic adhesins (SAs) enabling the rational design of the adhesion properties of E. coli. SAs have a modular structure comprising a stable β-domain for outer membrane anchoring and surface-exposed immunoglobulin domains with high affinity and specificity that can be selected from large repertoires. SAs are constitutively and stably expressed in an E. coli strain lacking a conserved set of natural adhesins, directing a robust, fast, and specific adhesion of bacteria to target antigenic surfaces and cells. We demonstrate the functionality of SAs in vivo, showing that, compared to wild type E. coli, lower doses of engineered E. coli are sufficient to colonize solid tumors expressing an antigen recognized by the SA. In addition, lower levels of engineered bacteria were found in non-target tissues. Therefore, SAs provide stable and specific adhesion capabilities to E. coli against target surfaces of interest for diverse applications using live bacteria.

  8. Surface Morphology and Tooth Adhesion of a Novel Nanostructured Dental Restorative Composite

    Directory of Open Access Journals (Sweden)

    Marco Salerno

    2016-03-01

    Full Text Available Recently, a novel dental restorative composite based on nanostructured micro-fillers of anodic porous alumina has been proposed. While its bulk properties are promising thanks to decreased aging and drug delivery capabilities, its surface properties are still unknown. Here we investigated the surface morphology and the adhesion to tooth dentin of this composite as prepared. For comparison, we used two commercial composites: Tetric EVO Flow (Ivoclar and Enamel HRi Plus (Micerium. The surface morphology was characterized by atomic force microscopy and the adhesion strength by tensile tests. The experimental composite is rougher than the commercial composites, with root mean square roughness of ~549 nm against 170–511 nm, and presents an adhesion strength of ~15 MPa against 19–21 MPa. These results show at the same time some proximity to the commercial composites, but also the need for optimization of the experimental material formulation.

  9. Salinity-Dependent Adhesion Response Properties of Aluminosilicate (K-Feldspar) Surfaces

    DEFF Research Database (Denmark)

    Lorenz, Bärbel; Ceccato, Marcel; Andersson, Martin Peter

    2017-01-01

    Flooding sandstone oil reservoirs with low salinity water can lead to a significant increase in oil recovery, a phenomenon called "the low salinity effect". Although there are many factors that contribute to this response, the surface tension on the pore walls is an important one. Sandstone...... is composed predominantly of quartz with some clay, but feldspar grains are often also present. While the wettability of quartz and clay surfaces has been thoroughly investigated, little is known about the adhesion properties of feldspar. We explored the interaction of model oil compounds, molecules...... in well sorted sandstone. Adhesion forces, measured with the chemical force mapping (CFM) mode of atomic force microscopy (AFM), showed a low salinity effect on the fresh feldspar surfaces. Adhesion force, measured with -COO(H)-functionalized tips, was 60% lower in artificial low salinity seawater (LS...

  10. Nano-materials for adhesive-free adsorbers for bakable extreme high vacuum cryopump surfaces

    Science.gov (United States)

    Stutzman, Marcy; Jordan, Kevin; Whitney, Roy R.

    2016-10-11

    A cryosorber panel having nanomaterials used for the cryosorption material, with nanomaterial either grown directly on the cryopanel or freestanding nanomaterials attached to the cryopanel mechanically without the use of adhesives. Such nanomaterial cryosorber materials can be used in place of conventional charcoals that are attached to cryosorber panels with special low outgassing, low temperature capable adhesives. Carbon nanotubes and other nanomaterials could serve the same purpose as conventional charcoal cryosorbers, providing a large surface area for cryosorption without the need for adhesive since the nanomaterials can be grown directly on a metallic substrate or mechanically attached. The nanomaterials would be capable of being fully baked by heating above 100.degree. C., thereby eliminating water vapor from the system, eliminating adhesives from the system, and allowing a full bake of the system to reduce hydrogen outgassing, with the goal of obtaining extreme high vacuum where the pump can produce pressures below 1.times.10.sup.-12 Torr.

  11. Zinc-ion implanted and deposited titanium surfaces reduce adhesion of Streptococccus mutans

    International Nuclear Information System (INIS)

    Xu Juan; Ding Gang; Li Jinlu; Yang Shenhui; Fang Bisong; Sun Hongchen; Zhou Yanmin

    2010-01-01

    While titanium (Ti) is a commonly used dental implant material with advantageous biocompatible and mechanical properties, native Ti surfaces do not have the ability to prevent bacterial colonization. The objective of this study was to evaluate the chemical composition and bacterial adhesive properties of zinc (Zn) ion implanted and deposited Ti surfaces (Zn-PIIID-Ti) as potential dental implant materials. Surfaces of pure Ti (cp-Ti) were modified with increasing concentrations of Zn using plasma immersion ion implantation and deposition (PIIID), and elemental surface compositions were characterized by X-ray photoelectron spectrometry (XPS). To evaluate bacterial responses, Streptococcus mutans were seeded onto the modifiedTi surfaces for 48 h and subsequently observed by scanning electron microscopy. Relative numbers of bacteria on each surface were assessed by collecting the adhered bacteria, reculturing and counting colony forming units after 48 h on bacterial grade plates. Ti, oxygen and carbon elements were detected on all surfaces by XPS. Increased Zn signals were detected on Zn-PIIID-Ti surfaces, correlating with an increase of Zn-deposition time. Substantial numbers of S. mutans adhered to cp-Ti samples, whereas bacterial adhesion on Zn-PIIID-Ti surfaces signficantly decreased as the Zn concentration increased (p < 0.01). In conclusion, PIIID can successfully introduce Zn onto a Ti surface, forming a modified surface layer bearing Zn ions that consequently deter adhesion of S. mutans, a common bacterium in the oral environment.

  12. Zinc-ion implanted and deposited titanium surfaces reduce adhesion of Streptococccus mutans

    Energy Technology Data Exchange (ETDEWEB)

    Xu Juan, E-mail: doctorxue@126.com [Implant Center, School of Stomatology Jilin University, Changchun, Jilin (China) and Stomatological Hospital, Urumqi, Xinjiang (China); Ding Gang [Department of Stomatology, Yidu Central Hospital, Weifang, Shandong (China); Capital Medical University School of Stomatology, Beijing (China); Li Jinlu; Yang Shenhui; Fang Bisong [Capital Medical University School of Stomatology, Beijing (China); Sun Hongchen, E-mail: hcsun@jlu.edu.cn [Implant Center, School of Stomatology Jilin University, Changchun, Jilin (China); Zhou Yanmin, E-mail: zhouym62@126.com [Implant Center, School of Stomatology Jilin University, Changchun, Jilin (China)

    2010-10-01

    While titanium (Ti) is a commonly used dental implant material with advantageous biocompatible and mechanical properties, native Ti surfaces do not have the ability to prevent bacterial colonization. The objective of this study was to evaluate the chemical composition and bacterial adhesive properties of zinc (Zn) ion implanted and deposited Ti surfaces (Zn-PIIID-Ti) as potential dental implant materials. Surfaces of pure Ti (cp-Ti) were modified with increasing concentrations of Zn using plasma immersion ion implantation and deposition (PIIID), and elemental surface compositions were characterized by X-ray photoelectron spectrometry (XPS). To evaluate bacterial responses, Streptococcus mutans were seeded onto the modifiedTi surfaces for 48 h and subsequently observed by scanning electron microscopy. Relative numbers of bacteria on each surface were assessed by collecting the adhered bacteria, reculturing and counting colony forming units after 48 h on bacterial grade plates. Ti, oxygen and carbon elements were detected on all surfaces by XPS. Increased Zn signals were detected on Zn-PIIID-Ti surfaces, correlating with an increase of Zn-deposition time. Substantial numbers of S. mutans adhered to cp-Ti samples, whereas bacterial adhesion on Zn-PIIID-Ti surfaces signficantly decreased as the Zn concentration increased (p < 0.01). In conclusion, PIIID can successfully introduce Zn onto a Ti surface, forming a modified surface layer bearing Zn ions that consequently deter adhesion of S. mutans, a common bacterium in the oral environment.

  13. Elastic–plastic adhesive impacts of tungsten dust with metal surfaces in plasma environments

    International Nuclear Information System (INIS)

    Ratynskaia, S.; Tolias, P.; Shalpegin, A.; Vignitchouk, L.; De Angeli, M.; Bykov, I.; Bystrov, K.; Bardin, S.; Brochard, F.; Ripamonti, D.; Harder, N. den; De Temmerman, G.

    2015-01-01

    Dust-surface collisions impose size selectivity on the ability of dust grains to migrate in scrape-off layer and divertor plasmas and to adhere to plasma-facing components. Here, we report first experimental evidence of dust impact phenomena in plasma environments concerning low-speed collisions of tungsten dust with tungsten surfaces: re-bouncing, adhesion, sliding and rolling. The results comply with the predictions of the model of elastic-perfectly plastic adhesive spheres employed in the dust dynamics code MIGRAINe for sub- to several meters per second impacts of micrometer-range metal dust

  14. Theoretical Models for Surface Forces and Adhesion and Their Measurement Using Atomic Force Microscopy

    Science.gov (United States)

    Leite, Fabio L.; Bueno, Carolina C.; Da Róz, Alessandra L.; Ziemath, Ervino C.; Oliveira, Osvaldo N.

    2012-01-01

    The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS), it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion. This review provides the theoretical and experimental background of AFS, adhesion forces, intermolecular interactions and surface forces in air, vacuum and in solution. PMID:23202925

  15. Theoretical models for surface forces and adhesion and their measurement using atomic force microscopy.

    Science.gov (United States)

    Leite, Fabio L; Bueno, Carolina C; Da Róz, Alessandra L; Ziemath, Ervino C; Oliveira, Osvaldo N

    2012-10-08

    The increasing importance of studies on soft matter and their impact on new technologies, including those associated with nanotechnology, has brought intermolecular and surface forces to the forefront of physics and materials science, for these are the prevailing forces in micro and nanosystems. With experimental methods such as the atomic force spectroscopy (AFS), it is now possible to measure these forces accurately, in addition to providing information on local material properties such as elasticity, hardness and adhesion. This review provides the theoretical and experimental background of afs, adhesion forces, intermolecular interactions and surface forces in air, vacuum and in solution.

  16. Elastic–plastic adhesive impacts of tungsten dust with metal surfaces in plasma environments

    Energy Technology Data Exchange (ETDEWEB)

    Ratynskaia, S., E-mail: svetlana.ratynskaia@ee.kth.se [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Tolias, P. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Shalpegin, A. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-lès-Nancy (France); Vignitchouk, L. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); De Angeli, M. [Istituto di Fisica del Plasma – Consiglio Nazionale delle Ricerche, Milan (Italy); Bykov, I. [KTH Royal Institute of Technology, Association EUROfusion-VR, Stockholm (Sweden); Bystrov, K.; Bardin, S. [FOM Institute DIFFER, Dutch Institute For Fundamental Energy Research, Edisonbaan 14, 3439MN Nieuwegein (Netherlands); Brochard, F. [Université de Lorraine, Institut Jean Lamour, Vandoeuvre-lès-Nancy (France); Ripamonti, D. [Istituto per l’Energetica e le Interfasi – Consiglio Nazionale delle Ricerche, Milan (Italy); Harder, N. den; De Temmerman, G. [FOM Institute DIFFER, Dutch Institute For Fundamental Energy Research, Edisonbaan 14, 3439MN Nieuwegein (Netherlands)

    2015-08-15

    Dust-surface collisions impose size selectivity on the ability of dust grains to migrate in scrape-off layer and divertor plasmas and to adhere to plasma-facing components. Here, we report first experimental evidence of dust impact phenomena in plasma environments concerning low-speed collisions of tungsten dust with tungsten surfaces: re-bouncing, adhesion, sliding and rolling. The results comply with the predictions of the model of elastic-perfectly plastic adhesive spheres employed in the dust dynamics code MIGRAINe for sub- to several meters per second impacts of micrometer-range metal dust.

  17. Influence of Surface Properties on Adhesion Forces and Attachment of Streptococcus mutans to Zirconia In Vitro

    Science.gov (United States)

    Yu, Pei; Wang, Chuanyong; Zhou, Jinglin; Jiang, Li

    2016-01-01

    Zirconia is becoming a prevalent material in dentistry. However, any foreign bodies inserted may provide new niches for the bacteria in oral cavity. The object of this study was to explore the effect of surface properties including surface roughness and hydrophobicity on the adhesion and biofilm formation of Streptococcus mutans (S. mutans) to zirconia. Atomic force microscopy was employed to determine the zirconia surface morphology and the adhesion forces between the S. mutans and zirconia. The results showed that the surface roughness was nanoscale and significantly different among tested groups (P Medium (17.00 ± 3.81 nm) > Fine (11.89 ± 1.68 nm). The contact angles of the Coarse group were the highest, followed by the Medium and the Fine groups. Increasing the surface roughness and hydrophobicity resulted in an increase of adhesion forces and early attachment (2 h and 4 h) of S. mutans on the zirconia but no influence on the further development of biofilm (6 h~24 h). Our findings suggest that the surface roughness in nanoscale and hydrophobicity of zirconia had influence on the S. mutans initial adhesion force and early attachment instead of whole stages of biofilm formation. PMID:27975061

  18. Enhanced adhesion of osteoblastic cells on polystyrene films by independent control of surface topography and wettability

    International Nuclear Information System (INIS)

    Yang, Seung Yun; Kim, Eung-Sam; Jeon, Gumhye; Choi, Kwan Yong; Kim, Jin Kon

    2013-01-01

    We independently controlled surface topography and wettability of polystyrene (PS) films by CF 4 and oxygen plasma treatments, respectively, to evaluate the adhesion and proliferation of human fetal osteoblastic (hFOB) cells on the films. Among the CF 4 plasma-treated PS films with the average surface roughness ranging from 0.9 to 70 nm, the highest adhesion of hFOB cells was observed on a PS film with roughness of ∼ 11 nm. When this film was additionally treated by oxygen plasma to provide a hydrophilic surface with a contact angle less than 10°, the proliferation of bone-forming cell was further enhanced. Thus, the plasma-based independent modification of PS film into an optimum nanotexture for human osteoblast cells could be appplied to materials used in bone tissue engineering. Highlights: ► New approach based on plasma treatment to independently control the surface topography and wettability ► The adhesion of human fetal osteoblast (hFOB) was enhanced on a surface with an average roughness of ∼ 11 nm. ► The adhesion and proliferation of hFOB was maximized when nanotextured surface became highly hydrophilic

  19. Role of surface layer collagen binding protein from indigenous Lactobacillus plantarum 91 in adhesion and its anti-adhesion potential against gut pathogen.

    Science.gov (United States)

    Yadav, Ashok Kumar; Tyagi, Ashish; Kaushik, Jai Kumar; Saklani, Asha Chandola; Grover, Sunita; Batish, Virender Kumar

    2013-12-14

    Human feacal isolates were ascertain as genus Lactobacillus using specific primer LbLMA1/R16-1 and further identified as Lactobacillus plantarum with species specific primers Lpl-3/Lpl-2. 25 L. plantarum strains were further assessed for hydrophobicity following the microbial adhesion to hydrocarbons (MATH) method and colonization potentials based on their adherence to immobilized human collagen type-1. Surface proteins were isolated from selected L. plantarum 91(Lp91) strain. The purified collagen binding protein (Cbp) protein was assessed for its anti-adhesion activity against enteric Escherichia coli 0157:H7 pathogen on immobilized collagen. Four L. plantarum strains displayed high degree of hydrophobicity and significant adhesion to collagen. A 72 kDa protein was purified which reduced 59.71% adhesion of E. coli 0157:H7 on immobilized collagen as compared to control well during adhesion assay. Cbp protein is the major influencing factor in inhibition of E. coli 0157:H7 adhesion with extracellular matrix (ECM) components. Hydrophobicity and adhesion potential are closely linked attributes precipitating in better colonization potential of the lactobacillus strains. Cbp is substantiated as a crucial surface protein contributing in adhesion of lactobacillus strains. The study can very well be the platform for commercialization of indigenous probiotic strain once their functional attributes are clinically explored. Copyright © 2013 Elsevier GmbH. All rights reserved.

  20. Influence of Surface Properties and Impact Conditions on Adhesion of Insect Residues

    Science.gov (United States)

    Wohl, Christopher J.; Smith, Joseph G.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Shanahan, Michelle H.; Penner, Ronald K.

    2015-01-01

    Insect residues can cause premature transition to turbulent flow on laminar flow airfoils. Engineered surfaces that mitigate the adhesion of insect residues provide, therefore, a route to more efficient aerodynamics and reduced fuel burn rates. Areal coverage and heights of residues depend not only on surface properties, but also on impact conditions. We report high speed photography of fruit fly impacts at different angles of inclination on a rigid aluminum surface, optical microscopy and profilometry, and contact angle goniometry to support the design of engineered surfaces. For the polyurethane and epoxy coatings studied, some of which exhibited superhydrophobicity, it was determined that impact angle and surface compositions play critical roles in the efficacy of these surfaces to reduce insect residue adhesion.

  1. Surface Treatment of Polymeric Materials Controlling the Adhesion of Biomolecules

    Directory of Open Access Journals (Sweden)

    Willy Zorzi

    2012-08-01

    Full Text Available This review describes different strategies of surface elaboration for a better control of biomolecule adsorption. After a brief description of the fundamental interactions between surfaces and biomolecules, various routes of surface elaboration are presented dealing with the attachment of functional groups mostly thanks to plasma techniques, with the grafting to and from methods, and with the adsorption of surfactants. The grafting of stimuli-responsive polymers is also pointed out. Then, the discussion is focused on the protein adsorption phenomena showing how their interactions with solid surfaces are complex. The adsorption mechanism is proved to be dependent on the solid surface physicochemical properties as well as on the surface and conformation properties of the proteins. Different behaviors are also reported for complex multiple protein solutions.

  2. Surface Treatment of Polymeric Materials Controlling the Adhesion of Biomolecules

    Science.gov (United States)

    Poncin-Epaillard, Fabienne; Vrlinic, Tjasa; Debarnot, Dominique; Mozetic, Miran; Coudreuse, Arnaud; Legeay, Gilbert; El Moualij, Benaïssa; Zorzi, Willy

    2012-01-01

    This review describes different strategies of surface elaboration for a better control of biomolecule adsorption. After a brief description of the fundamental interactions between surfaces and biomolecules, various routes of surface elaboration are presented dealing with the attachment of functional groups mostly thanks to plasma techniques, with the grafting to and from methods, and with the adsorption of surfactants. The grafting of stimuli-responsive polymers is also pointed out. Then, the discussion is focused on the protein adsorption phenomena showing how their interactions with solid surfaces are complex. The adsorption mechanism is proved to be dependent on the solid surface physicochemical properties as well as on the surface and conformation properties of the proteins. Different behaviors are also reported for complex multiple protein solutions. PMID:24955631

  3. Adhesion forces in liquid media: effect of surface topography and wettability.

    Science.gov (United States)

    Serro, A P; Colaço, R; Saramago, B

    2008-09-15

    This work was motivated by the unexpected values of adhesion forces measured between an atomic force microscopy tip and the hydrophobic surface of ultra-high-molecular-weight polyethylene. Two types of samples with different roughness but similar wettability were tested. Adhesion forces of similar magnitude were obtained in air and in polar liquids (water and Hank's Balanced Salt Solution, a saline solution) with the rougher sample. In contrast, the adhesion forces measured on the smoother sample in air were much higher than those measured in water or in the aqueous solution. Those experimental results suggested the presence of nanobubbles at the interface between the rough sample and the polar liquids. The existence of the nanobubbles was further confirmed by the images of the interface obtained in noncontact tapping mode. The adhesion forces measured in a nonpolar liquid (hexadecane) were small and of the same order of magnitude for both samples and their values were in good agreement with the predictions of the London-Hamaker approach for the van der Waals interactions. Finally, we correlate the appearance of nanobubbles with surface topography. The conclusion of this work is that adhesion forces measured in aqueous media may be strongly affected by the presence of nanobubbles if the surface presents topographical accidents.

  4. Surface strategies for control of neuronal cell adhesion: A review

    Science.gov (United States)

    Roach, P.; Parker, T.; Gadegaard, N.; Alexander, M. R.

    2010-06-01

    Material engineering methods have been used for many years to develop biomedical devices for use within the body to augment, repair or replace damaged tissues ranging from contact lenses to heart valves. Here we review the findings gathered from the wide and varied surface analytical approaches applied to study the interaction between biology and man-made materials. The key material characteristics identified to be important for biological recognition are surface chemistry, topography and compliance. Model surfaces with controlled chemistry and topography have provided insight into biological response to various types of topographical features over a wide range of length scales from nano to micrometres, along with 3D matrices that have been used as scaffolds to support cells for tissue formation. The cellular response to surfaces with localised areas of patterned chemistry and to those presenting gradually changing chemistry are discussed. Where previous reviews have been structured around specific classes of surface modification, e.g. self-assembly, or have broadly examined the response of various cells to numerous surfaces, we aim in this article to focus in particular on the tissues involved in the nervous system whilst providing a broad overview of key issues from the field of cell and protein surface interactions with surfaces. The goal of repair and treatment of diseases related to the central and peripheral nervous systems rely on understanding the local interfacial environment and controlling responses at the cellular level. The role of the protein layer deposited from serum containing media onto man-made surfaces is discussed. We highlight the particular problems associated with the repair of the nervous system, and review how neuronal attachment and axon guidance can be accomplished using various surface cues when cultured with single and multiple cell types. We include a brief glossary of techniques discussed in the body of this article aimed at the

  5. Reversibility of bacterial adhesion at an electrode surface

    NARCIS (Netherlands)

    Poortinga, AT; Busscher, HJ; Bos, R.R.M.

    2001-01-01

    Deposition of four bacterial strains from a 1 mM potassium phosphate buffer (pH 7) to an indium tin oxide (ITO) electrode surface has been studied in a parallel plate flow chamber at three electrode potentials (-0.2, 0.1, and 0.5 V). Capacitance measurements demonstrated that the ITO surface was

  6. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  7. Surface Characterization and Cell Adhesion of Different Zirconia Treatments: An in vitro Study.

    Science.gov (United States)

    Nassif, Wadih; Rifai, Mohamad

    2018-02-01

    The aim of this study was to characterize the surface of zirconia subjected to different treatments and evaluate its effect on cell adhesion and proliferation. A total of 80 zirconia disks were divided into four groups (n = 20) according to the surface treatments used: group I: as-sintered (AS), no surface treatment applied; group II: abrasion treatment applied using Rocatec (ROC; 3M ESPE) system with silica-coated alumina powder of grit size 110 μm; group III: erbium, chromium:yttrium, scandium, gallium, garnet (Er, Cr:YSGG) laser (LAS; BIOLASE) was used at a frequency of 20 Hz and output power of 3 W; and group IV: specimens were subjected to the selective infiltration etching (SIE) technique. Surface characterization was evaluated for the different groups (roughness, hardness, and morphology), and cell behavior (adhesion and proliferation) was tested (a = 0.05). The ROC group reported a significant increase in surface roughness (2.201 ± 0.352) and Vickers hardness (1758 ± 16.6) compared with the other surface treatments. The SIE surface-treated group reported a significantly higher number of cells (64.5 ± 2.6 and 53.5 ± 2.2 respectively) compared with the other surface-treated groups. The SIE is a promising surface treatment for zirconia that significantly enhances cell adhesion and osseointegration. The SIE treatment of zirconia implants may help in a faster and better osseointegration.

  8. In vivo evaluation of defined polished titanium surfaces to prevent soft tissue adhesion.

    Science.gov (United States)

    Hayes, Jessica S; Welton, Joanne L; Wieling, Ronald; Richards, R Geoff

    2012-04-01

    Soft tissue-implant adhesion is often required for implant integration into the body; however, in some situations, the tissue is required to glide freely over an implant. In the case of distal radius fracture treatment, current literature describes how titanium and its alloys tend to lead to more intra-tendon inflammatory reactions compared with stainless steel. This leads to tendon-implant adhesion and damage possibly causing limited palmar flexion and even tendon rupture. The goal of this study was to analyze the effect of different surface polishings of titanium and titanium molybdenum implants on soft tissue reactions in vivo, with the aim to prevent direct soft tissue adhesion. Using a nonfracture model, to allow for study of the soft-tissue-implant surface interactions only, six surface variants of the same plate design were implanted onto the tibia of 24 New Zealand white rabbits and left in situ for 12 weeks. Results indicate that paste polished commercially pure titanium and titanium molybdenum alloy had the least soft tissue adhesion, with the concomitant development of a soft tissue capsule. Surface topography did not appear influence the thickness of the connective tissue surrounding the plate. Therefore, suitable surface polishing could be applied to plates for clinical use, where free gliding of tissues is required. Copyright © 2012 Wiley Periodicals, Inc.

  9. Bacterial filamentation accelerates colonization of adhesive spots embedded in biopassive surfaces

    International Nuclear Information System (INIS)

    Möller, Jens; Emge, Philippe; Vizcarra, Ima Avalos; Kollmannsberger, Philip; Vogel, Viola

    2013-01-01

    Sessile bacteria adhere to engineered surfaces and host tissues and pose a substantial clinical and economical risk when growing into biofilms. Most engineered and biological interfaces are of chemically heterogeneous nature and provide adhesive islands for bacterial attachment and growth. To mimic either defects in a surface coating of biomedical implants or heterogeneities within mucosal layers (Peyer's patches), we embedded micrometre-sized adhesive islands in a poly(ethylene glycol) biopassive background. We show experimentally and computationally that filamentation of Escherichia coli can significantly accelerate the bacterial surface colonization under physiological flow conditions. Filamentation can thus provide an advantage to a bacterial population to bridge non-adhesive distances exceeding 5 μm. Bacterial filamentation, caused by blocking of bacterial division, is common among bacterial species and can be triggered by environmental conditions or antibiotic treatment. While great awareness exists that the build-up of antibiotic resistance serves as intrinsic survival strategy, we show here that antibiotic treatment can actually promote surface colonization by triggering filamentation, which in turn prevents daughter cells from being washed away. Our combined microfabrication and computational approaches provide quantitative insights into mechanisms that enable biofouling of biopassive surfaces with embedded adhesive spots, even for spot distances that are multiples of the bacterial length. (paper)

  10. Bacterial filamentation accelerates colonization of adhesive spots embedded in biopassive surfaces

    Science.gov (United States)

    Möller, Jens; Emge, Philippe; Avalos Vizcarra, Ima; Kollmannsberger, Philip; Vogel, Viola

    2013-12-01

    Sessile bacteria adhere to engineered surfaces and host tissues and pose a substantial clinical and economical risk when growing into biofilms. Most engineered and biological interfaces are of chemically heterogeneous nature and provide adhesive islands for bacterial attachment and growth. To mimic either defects in a surface coating of biomedical implants or heterogeneities within mucosal layers (Peyer's patches), we embedded micrometre-sized adhesive islands in a poly(ethylene glycol) biopassive background. We show experimentally and computationally that filamentation of Escherichia coli can significantly accelerate the bacterial surface colonization under physiological flow conditions. Filamentation can thus provide an advantage to a bacterial population to bridge non-adhesive distances exceeding 5 μm. Bacterial filamentation, caused by blocking of bacterial division, is common among bacterial species and can be triggered by environmental conditions or antibiotic treatment. While great awareness exists that the build-up of antibiotic resistance serves as intrinsic survival strategy, we show here that antibiotic treatment can actually promote surface colonization by triggering filamentation, which in turn prevents daughter cells from being washed away. Our combined microfabrication and computational approaches provide quantitative insights into mechanisms that enable biofouling of biopassive surfaces with embedded adhesive spots, even for spot distances that are multiples of the bacterial length.

  11. Handling sticky Resin by Stingless Bees: Adhesive Properties of Surface Structures

    Directory of Open Access Journals (Sweden)

    MARKUS GASTAUER

    2013-09-01

    Full Text Available Many Stingless Bees (Hymenoptera: Meliponini like Tetragonisca angustula collect resin to defend their nests against intruders like ants or Robber Bees. Small portions of resin are attached to intruders bodies and extremities causing their immobilization. It has been observed that resin is removed easily from the bee's mandible but adheres strongly to the intruder's cuticle. We tested the hypothesis that resin sticks lesser to the mandibles of Stingless Bees than to the surface of intruders due to special surface structures or adhesive properties of these structures. The surface structures of the mandible of T. angustula and the trochanter of Camponotus sericeiventris were studied by scanning electron microscopy. To measure adhesion properties, selected surfaces were fixed on a fine glass pin and withdrawn from a glass tip covered with resin. The deformation of the glass pin indicates adhesion forces operating between the resin and the selective surface. The absolute value of the forces is computed from the glass pin's stiffness. It has been shown that resin sticks more to the smooth mandible of the bee than to the structured trochanter of the ant. A new hypothesis to be tested says that the bees might lubricate their mandibles with nectar or honey to reduce the resin's adhesion temporarily.

  12. Membrane Surface Nanostructures and Adhesion Property of T Lymphocytes Exploited by AFM

    Directory of Open Access Journals (Sweden)

    Lu Hongsong

    2009-01-01

    Full Text Available Abstract The activation of T lymphocytes plays a very important role in T-cell-mediated immune response. Though there are many related literatures, the changes of membrane surface nanostructures and adhesion property of T lymphocytes at different activation stages have not been reported yet. However, these investigations will help us further understand the biophysical and immunologic function of T lymphocytes in the context of activation. In the present study, the membrane architectures of peripheral blood T lymphocytes were obtained by AFM, and adhesion force of the cell membrane were measured by acquiring force–distance curves. The results indicated that the cell volume increased with the increases of activation time, whereas membrane surface adhesion force decreased, even though the local stiffness for resting and activated cells is similar. The results provided complementary and important data to further understand the variation of biophysical properties of T lymphocytes in the context of in vitro activation.

  13. The influence of surface modification on bacterial adhesion to titanium-based substrates.

    Science.gov (United States)

    Lorenzetti, Martina; Dogša, Iztok; Stošicki, Tjaša; Stopar, David; Kalin, Mitjan; Kobe, Spomenka; Novak, Saša

    2015-01-28

    This study examines bacterial adhesion on titanium-substrates used for bone implants. Adhesion is the most critical phase of bacterial colonization on medical devices. The surface of titanium was modified by hydrothermal treatment (HT) to synthesize nanostructured TiO2-anatase coatings, which were previously proven to improve corrosion resistance, affect the plasma protein adsorption, and enhance osteogenesis. The affinity of the anatase coatings toward bacterial attachment was studied by using a green fluorescent protein-expressing Escherichia coli (gfp-E. coli) strain in connection with surface photoactivation by UV irradiation. We also analyzed the effects of surface topography, roughness, charge, and wettability. The results suggested the dominant effects of the macroscopic surface topography, as well as microasperity at the surface roughness scale, which were produced during titanium machining, HT treatment, or both. Macroscopic grooves provided a preferential site for bacteria deposit within the valleys, while the microscopic roughness of the valleys determined the actual interaction surface between bacterium and substrate, resulting in an "interlocking" effect and undesired high bacterial adhesion on nontreated titanium. In the case of TiO2-coated samples, the nanocrystals reduced the width between the microasperities and thus added nanoroughness features. These factors decreased the contact area between the bacterium and the coating, with consequent lower bacterial adhesion (up to 50% less) in comparison to the nontreated titanium. On the other hand, the pronounced hydrophilicity of one of the HT-coated discs after pre-irradiation seemed to enhance the attachment of bacteria, although the increase was not statistically significant (p > 0.05). This observation may be explained by the acquired similar degree of wetting between gfp-E. coli and the coating. No correlation was found between the bacterial adhesion and the ζ-values of the samples in PBS, so the

  14. Surface meteorology and Solar Energy

    Science.gov (United States)

    Stackhouse, Paul W. (Principal Investigator)

    The Release 5.1 Surface meteorology and Solar Energy (SSE) data contains parameters formulated for assessing and designing renewable energy systems. Parameters fall under 11 categories including: Solar cooking, solar thermal applications, solar geometry, tilted solar panels, energy storage systems, surplus product storage systems, cloud information, temperature, wind, other meteorological factors, and supporting information. This latest release contains new parameters based on recommendations by the renewable energy industry and it is more accurate than previous releases. On-line plotting capabilities allow quick evaluation of potential renewable energy projects for any region of the world. The SSE data set is formulated from NASA satellite- and reanalysis-derived insolation and meteorological data for the 10-year period July 1983 through June 1993. Results are provided for 1 degree latitude by 1 degree longitude grid cells over the globe. Average daily and monthly measurements for 1195 World Radiation Data Centre ground sites are also available. [Mission Objectives] The SSE project contains insolation and meteorology data intended to aid in the development of renewable energy systems. Collaboration between SSE and technology industries such as the Hybrid Optimization Model for Electric Renewables ( HOMER ) may aid in designing electric power systems that employ some combination of wind turbines, photovoltaic panels, or diesel generators to produce electricity. [Temporal_Coverage: Start_Date=1983-07-01; Stop_Date=1993-06-30] [Spatial_Coverage: Southernmost_Latitude=-90; Northernmost_Latitude=90; Westernmost_Longitude=-180; Easternmost_Longitude=180].

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    Some strains of the food borne pathogen Listeria monocytogenes persist in food processing environments. The exact reason behind this phenomenon is not known, but strain differences in the ability to adhere to solid surfaces could offer an explanation. In the present work, initial adhesion of nine...... strains of L. monocytogenes was investigated under liquid flow at two levels of shear stress on six different surfaces using a flow chamber set-up with microscopy measurements. The surfaces tested were glass and PVC, and glass coated with beef extract, casein, and homogenised and unhomogenised milk....... In addition, the effect of prior environmental stress (5% NaCl, low nutrient availability) on initial adhesion was investigated. The hydrophobicity of the investigated surfaces was determined by contact angle measurements and the surface properties of the investigated L. monocytogenes strains were determined...

  16. Effect of surface treatments on the flexural properties and adhesion of glass fiber-reinforced composite post to self-adhesive luting agent and radicular dentin.

    Science.gov (United States)

    Elnaghy, Amr M; Elsaka, Shaymaa E

    2016-01-01

    This study evaluated the effect of different surface treatments on the flexural properties and adhesion of glass fiber post to self-adhesive luting agent and radicular dentin. Seventy-five single-rooted human teeth were prepared to receive a glass fiber post (Reblida). The posts were divided into five groups according to the surface treatment: Gr C (control; no treatment), Gr S (silanization for 60 s), Gr AP (airborne-particle abrasion), Gr HF (etching with 9 % hydrofluoric acid for 1 min), and Gr M10 (etching with CH2Cl2 for 10 min). Dual-cure self-adhesive luting agent (Rely X Unicem) was applied to each group for testing the adhesion using micropush-out test. Failure types were examined with stereomicroscope and surface morphology of the posts was characterized using a scanning electron microscopy (SEM). Flexural properties of posts were assessed using a three-point bending test. Data were analyzed using ANOVA and Tukey's HSD test. Statistical significance was set at the 0.05 probability level. Groups treated with M10 showed significantly higher bond strength than those obtained with other surface treatments (P C > S > AP > HF. Most failure modes were adhesive type of failures between dentin and luting agent (48.2%). SEM analysis revealed that the fiber post surfaces were modified after surface treatments. The surface treatments did not compromise the flexural properties of fiber posts. Application of M10 to the fiber post surfaces enhanced the adhesion to self-adhesive luting agent and radicular dentin.

  17. Biofilm-Forming Staphylococcus epidermidis Expressing Vancomycin Resistance Early after Adhesion to a Metal Surface

    Directory of Open Access Journals (Sweden)

    Toshiyuki Sakimura

    2015-01-01

    Full Text Available We investigated biofilm formation and time of vancomycin (VCM resistance expression after adhesion to a metal surface in Staphylococcus epidermidis. Biofilm-forming Staphylococcus epidermidis with a VCM MIC of 1 μg/mL was used. The bacteria were made to adhere to a stainless steel washer and treated with VCM at different times and concentrations. VCM was administered 0, 2, 4, and 8 hours after adhesion. The amount of biofilm formed was evaluated based on the biofilm coverage rates (BCRs before and after VCM administration, bacterial viability in biofilm was visually observed using the fluorescence staining method, and the viable bacterial count in biofilm was measured. The VCM concentration required to decrease BCR significantly compared with that of VCM-untreated bacteria was 4 μg/mL, even in the 0 hr group. In the 4 and 8 hr groups, VCM could not inhibit biofilm growth even at 1,024 μg/mL. In the 8 hr group, viable bacteria remained in biofilm at a count of 104 CFU even at a high VCM concentration (1,024 μg/mL. It was suggested that biofilm-forming Staphylococcus epidermidis expresses resistance to VCM early after adhesion to a metal surface. Resistance increased over time after adhesion as the biofilm formed, and strong resistance was expressed 4–8 hours after adhesion.

  18. A Maugis-Dugdale cohesive solution for adhesion of a surface with a dimple.

    Science.gov (United States)

    Papangelo, A; Ciavarella, M

    2017-02-01

    We study the adhesion of a surface with a 'dimple' which shows a mechanism for a bi-stable adhesive system in surfaces with spaced patterns of depressions, leading to adhesion enhancement, high dissipation and hysteresis. Recent studies were limited mainly to the very short range of adhesion (the so-called JKR regime), while we generalize the study to a Maugis cohesive model. A 'generalized Tabor parameter', given by the ratio of theoretical strength to elastic modulus, multiplied by the ratio of dimple width to depth has been found. It is shown that bistability disappears for generalized Tabor parameter less than about 2. Introduction of the theoretical strength is needed to have significant results when the system has gone in full contact, unless one postulates alternative limits to full contact, such as air entrapment, contaminants or fine scale roughness. Simple equations are obtained for the pull-off and for the full contact pressure in the entire set of the two governing dimensionless parameters. A qualitative comparison with results of recent experiments with nanopatterned bioinspired dry adhesives is attempted in light of the present model. © 2017 The Author(s).

  19. Relationships between surface coverage ratio and powder mechanics of binary adhesive mixtures for dry powder inhalers.

    Science.gov (United States)

    Rudén, Jonas; Frenning, Göran; Bramer, Tobias; Thalberg, Kyrre; Alderborn, Göran

    2018-04-25

    The aim of this paper was to study relationships between the content of fine particles and the powder mechanics of binary adhesive mixtures and link these relationships to the blend state. Mixtures with increasing amounts of fine particles (increasing surface coverage ratios (SCR)) were prepared using Lactopress SD as carrier and micro particles of lactose as fines (2.7 µm). Indicators of unsettled bulk density, compressibility and flowability were derived and the blend state was visually examined by imaging. The powder properties studied showed relationships to the SCR characterised by stages. At low SCR, the fine particles predominantly gathered in cavities of the carriers, giving increased bulk density and unchanged or improved flow. Thereafter, increased SCR gave a deposition of particles at the enveloped carrier surface with a gradually more irregular adhesion layer leading to a reduced bulk density and a step-wise reduced flowability. The mechanics of the mixtures at a certain stage were dependent on the structure and the dynamics of the adhesion layer and transitions between the stages were controlled by the evolution of the adhesion layer. It is advisable to use techniques based on different types of flow in order to comprehensively study the mechanics of adhesive mixtures. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Elastic–plastic adhesive contact of non-Gaussian rough surfaces

    Indian Academy of Sciences (India)

    Abstract. The paper describes an analysis of adhesion at the contact between non-. Gaussian rough surfaces using the Weibull distribution with skewness as the key parameter to characterize asymmetry. The analysis uses an improved elastic–plastic model of contact deformation that is based on accurate Finite Element ...

  1. Adhesive friction for elastic-plastic contacting rough surfaces considering asperity interaction

    International Nuclear Information System (INIS)

    Sahoo, Prasanta

    2006-01-01

    The paper describes a theoretical study of adhesive friction at the contact between rough surfaces taking asperity interaction into consideration and using an elastic-plastic model of contact deformation that is based on an accurate finite element analysis of an elastic-plastic single asperity contact. The micro-contact model of asperity interactions, developed by Zhao and Chang, is integrated into the improved elastic-plastic rough surface adhesive contact analysis to consider the adhesive friction behaviour of rough surfaces. The model considers a large range of interference values from fully elastic through elastic-plastic to fully plastic regimes of contacting asperities. Two well-established adhesion indices are used to consider different conditions that arise as a result of varying load, surface and material parameters. Results are obtained for the coefficient of friction against applied load for various combinations of these parameters. The results show that the coefficient of friction depends strongly on the applied load for the no-interaction case while it becomes insensitive to the load for interaction consideration. Moreover, the inclusion of elastic-plastic asperities further reduces the friction coefficient

  2. In vitro leukocyte adhesion to modified polyurethane surfaces. II. Effect of wettability

    NARCIS (Netherlands)

    Bruil, Anton; Bruil, A.; Brenneisen, L.M.; Brenneisen, Laura M.; Terlingen, Johannes G.A.; Terlingen, J.G.A.; Beugeling, T.; Beugeling, Tom; van Aken, W.G.; Feijen, Jan

    1994-01-01

    The influence of substrate wettability on leukocyte adhesion was studied using a series of polyurethane films with different surface wettabilities, prepared by a two step gas plasma modification procedure. In the first step the films were made hydrophobic by exposure to a tetrafluoromethane plasma.

  3. Direct observation of adhesion and spreading of emulsion droplets at solid surfaces

    NARCIS (Netherlands)

    Dresselhuis, D.M.; Aken, van G.A.; Hoog, de E.H.A.; Cohen Stuart, M.A.

    2008-01-01

    Sensory perception of fat is related to orally perceived in-mouth friction. From this perspective, we investigate adhesion and spreading of emulsion droplets on solid surfaces and connect it to the ability of food emulsions to lower friction. Furthermore, we study what the contribution is of the

  4. Effect of adhesive resin type for bonding to zirconia using two surface pretreatments

    NARCIS (Netherlands)

    Samimi, P.; Hasankhani, A.; Matinlinna, J.P.; Mirmohammadi, H.

    2015-01-01

    Purpose: This laboratory study evaluated the short-term adhesive properties of one 10-MDP-containing and two MDP-free resin composite cements, using two types of zirconia surface pretreatments. Materials and Methods: Eighteen sintered zirconia disks (Procera, Nobel Biocare) were randomly divided

  5. Titanium Surface Coating with a Laminin-Derived Functional Peptide Promotes Bone Cell Adhesion

    Directory of Open Access Journals (Sweden)

    Seung-Ki Min

    2013-01-01

    Full Text Available Laminin-derived peptide coatings can enhance epithelial cell adhesion to implants, and the positive effect of these peptides on bone cell adhesion has been anticipated. The purpose of this study was to evaluate the improvement in bone cell attachment to and activity on titanium (Ti scaffolds coated with a laminin-derived functional peptide, Ln2-P3 (the DLTIDDSYWYRI motif. Four Ti disc surfaces were prepared, and a human osteosarcoma (HOS cell attachment test was performed to select two candidate surfaces for peptide coating. These two candidates were then coated with Ln2-P3 peptide, a scrambled peptide, or left uncoated to measure cell attachment to each surface, following which one surface was chosen to assess alkaline phosphatase (ALP activity and osteogenic marker gene expression with quantitative real-time PCR. On the commercially pure Ti surface, the Ln2-P3 coating significantly increased cellular ALP activity and the expression levels of ALP and bone sialoprotein mRNA as compared with the scrambled peptide-coated and uncoated surfaces. In conclusion, although further in vivo studies are needed, the findings of this in vitro study indicate that the Ln2-P3-coated implant surface promotes bone cell adhesion, which has clinical implications for reducing the overall treatment time of dental implant therapy.

  6. Effect of Abrasive Waterjet Peening Surface Treatment of Steel Plates on the Strength of Single-Lap Adhesive Joints

    Directory of Open Access Journals (Sweden)

    Kamil Anasiewicz

    2017-09-01

    Full Text Available The paper presents results of comparative study of shear strength of single–lap adhesive joints, depending on the method of surface preparation of steel plates with increased corrosion resistance. The method of preparing adherend surfaces is often one of the most important factors determining the strength of adhesive joints. Appropriate geometric surface development and cleaning of the surface enhances adhesion forces between adherend material and adhesive. One of the methods of shaping engineering materials is waterjet cutting, which in the AWJP – abrasive waterjet peening variant, serves to shape flat surfaces of the material by changing the roughness and introducing stresses into the surface layer. These changes are valuable when preparing adhesive joints. In the study, surface roughness parameters obtained with AWJP treatment, were analyzed in direct relation to the strength of the adhesive joint. As a consequence of the experimental results analysis, the increase in the strength of the adhesive joints was observed in a certain range of parameters used for AWJP treatment. A decrease in shear strength of adhesive joint with the most modified topography of overlap surface was observed.

  7. Facile preparation of superhydrophobic surface with high adhesive ...

    Indian Academy of Sciences (India)

    Glass substrates modified by carbon/silica composites are fabricated through a two-step process for the preparation of a superhydrophobic surface (water contact angle ≥ 150°). Carbon nanoparticles were first prepared through a deposition process on glass using a hydrothermal synthesis route, then the glass was ...

  8. Facile preparation of superhydrophobic surface with high adhesive ...

    Indian Academy of Sciences (India)

    a nearly perfect spherical shape on lotus leaves, which can be rolled off easily, is one of the most beautiful wonders of nature. This natural phenomenon is known as lotus .... by treatment with fluorosilicone, its WCA is 152. ◦. (inset of figure 3(b)), which indicates that the surface of the glass has superhydrophobic property.

  9. Surface effects in adhesion, friction, wear, and lubrication

    National Research Council Canada - National Science Library

    Buckley, Donald H

    1981-01-01

    ... for carbon bodies to improve their wear resistance in high altitude aircraft generator applications. Basic researchers found that moisture in the carbon was critical t o its lubrication. Therefore, the presence of moisture o n the surface of the carbon was important. With it present, the carbon lubricated very effectively and very low wear was ...

  10. Antimicrobial design of titanium surface that kill sessile bacteria but support stem cells adhesion

    Science.gov (United States)

    Zhu, Chen; Bao, Ni-Rong; Chen, Shuo; Zhao, Jian-Ning

    2016-12-01

    Implant-related bacterial infection is one of the most severe postoperative complications in orthopedic or dental surgery. In this context, from the perspective of surface modification, increasing efforts have been made to enhance the antibacterial capability of titanium surface. In this work, a hierarchical hybrid surface architecture was firstly constructed on titanium surface by two-step strategy of acid etching and H2O2 aging. Then silver nanoparticles were firmly immobilized on the hierarchical surface by ion implantation, showing no detectable release of silver ions from surface. The designed titanium surface showed good bioactivity. More importantly, this elaborately designed titanium surface can effectively inactivate the adherent S. aureus on surface by virtue of a contact-killing mode. Meanwhile, the designed titanium surface can significantly facilitate the initial adhesion and spreading behaviors of bone marrow mesenchymal stem cells (MSCs) on titanium. The results suggested that, the elaborately designed titanium surface might own a cell-favoring ability that can help mammalian cells win the initial adhesion race against bacteria. We hope the present study can provide a new insight for the better understanding and designing of antimicrobial titanium surface, and pave the way to satisfying clinical requirements.

  11. Laser-based surface patterning of composite plates for improved secondary adhesive bonding

    KAUST Repository

    Tao, Ran

    2018-03-01

    The effects of laser irradiation surface pretreatments on the mode I fracture toughness of adhesively bonded composite joints were evaluated. First, pulsed CO2 laser irradiation was uniformly deployed on carbon fiber reinforced polymer (CFRP) substrates. Next, double cantilever beam (DCB) tests were performed to assess the effects of surface pretreatments on the mode I fracture toughness of the adhesive joints. Then, a thoughtful combination of the proposed surface pretreatments was deployed to fabricate DCB specimens with patterned interfaces. A wide range of techniques, including X-ray photoelectron spectroscopy (XPS), contact profilometry, and optical and scanning electron microscopy (SEM) were used to ascertain the effects of all investigated surface pretreatments. It is shown that patterning promoted damage mechanisms that were not observed in the uniformly treated interfaces, resulting in an effective fracture toughness well above that predicted by a classical rule of mixture.

  12. Adhesion, invasion and evasion: the many functions of the surface proteins of Staphylococcus aureus

    Science.gov (United States)

    Foster, Timothy J.; Geoghegan, Joan A.; Ganesh, Vannakambadi K.; Höök, Magnus

    2014-01-01

    Staphylococcus aureus is an important opportunistic pathogen and persistently colonizes about 20% of the human population. Its surface is ‘decorated’ with proteins that are covalently anchored to the cell wall peptidoglycan. Structural and functional analysis has identified four distinct classes of surface proteins, of which microbial surface component recognizing adhesive matrix molecules (MSCRAMMs) are the largest class. These surface proteins have numerous functions, including adhesion to and invasion of host cells and tissues, evasion of immune responses and biofilm formation. Thus, cell wall-anchored proteins are essential virulence factors for the survival of S. aureus in the commensal state and during invasive infections, and targeting them with vaccines could combat S. aureus infections. PMID:24336184

  13. Cell surface heparan sulfate proteoglycans control adhesion and invasion of breast carcinoma cells

    DEFF Research Database (Denmark)

    Lim, Hooi Ching; Multhaupt, Hinke A. B.; Couchman, John R.

    2015-01-01

    Background: Cell surface proteoglycans interact with numerous regulators of cell behavior through their glycosaminoglycan chains. The syndecan family of transmembrane proteoglycans are virtually ubiquitous cell surface receptors that are implicated in the progression of some tumors, including bre...... syndecan-2, may be important regulators of breast carcinoma progression through regulation of cytoskeleton, cell adhesion and invasion.......Background: Cell surface proteoglycans interact with numerous regulators of cell behavior through their glycosaminoglycan chains. The syndecan family of transmembrane proteoglycans are virtually ubiquitous cell surface receptors that are implicated in the progression of some tumors, including...... breast carcinoma. This may derive from their regulation of cell adhesion, but roles for specific syndecans are unresolved. Methods: The MDA-MB231 human breast carcinoma cell line was exposed to exogenous glycosaminoglycans and changes in cell behavior monitored by western blotting, immunocytochemistry...

  14. Determination of the attractive force, adhesive force, adhesion energy and Hamaker constant of soot particles generated from a premixed methane/oxygen flame by AFM

    Science.gov (United States)

    Liu, Ye; Song, Chonglin; Lv, Gang; Chen, Nan; Zhou, Hua; Jing, Xiaojun

    2018-03-01

    Atomic force microscopy (AFM) was used to characterize the attractive force, adhesive force and adhesion energy between an AFM probe tip and nanometric soot particle generated by a premixed methane/oxygen flame. Different attractive force distributions were found when increasing the height above burner (HAB), with forces ranging from 1.1-3.5 nN. As the HAB was increased, the average attractive force initially increased, briefly decreased, and then underwent a gradual increase, with a maximum of 2.54 nN observed at HAB = 25 mm. The mean adhesive force was 6.5-7.5 times greater than the mean attractive force at the same HAB, and values were in the range of 13.5-24.5 nN. The adhesion energy was in the range of 2.0-5.6 × 10-17 J. The variations observed in the average adhesion energy with increasing HAB were different from those of the average adhesion force, implying that the stretched length of soot particles is an important factor affecting the average adhesion energy. The Hamaker constants of the soot particles generated at different HABs were determined from AFM force-separation curves. The average Hamaker constant exhibited a clear correlation with the graphitization degree of soot particles as obtained from Raman spectroscopy.

  15. Bacterial Adhesion and Surface Roughness for Different Clinical Techniques for Acrylic Polymethyl Methacrylate.

    Science.gov (United States)

    Dantas, Lucas Costa de Medeiros; da Silva-Neto, João Paulo; Dantas, Talita Souza; Naves, Lucas Zago; das Neves, Flávio Domingues; da Mota, Adérito Soares

    2016-01-01

    This study sought to assess the effect of different surface finishing and polishing protocols on the surface roughness and bacterial adhesion (S. sanguinis) to polymethyl methacrylates (PMMA). Fifty specimens were divided into 5 groups (n = 10) according to their fabrication method and surface finishing protocol: LP (3 : 1 ratio and laboratory polishing), NF (Nealon technique and finishing), NP (Nealon technique and manual polishing), MF (3 : 1 ratio and manual finishing), and MP (3 : 1 ratio and manual polishing). For each group, five specimens were submitted to bacterial adhesion tests and analyzed by scanning electron microscopy (SEM). Two additional specimens were subjected to surface topography analysis by SEM and the remaining three specimens were subjected to surface roughness measurements. Data were compared by one-way ANOVA. The mean bacterial counts were as follows: NF, 19.6 ± 3.05; MP, 5.36 ± 2.08; NP, 4.96 ± 1.93; MF, 7.36 ± 2.45; and LP, 1.56 ± 0.62 (CFU). The mean surface roughness values were as follows: NF, 3.23 ± 0.15; MP, 0.52 ± 0.05; NP, 0.60 ± 0.08; MF, 2.69 ± 0.12; and LP, 0.07 ± 0.02 (μm). A reduction in the surface roughness was observed to be directly related to a decrease in bacterial adhesion. It was verified that the laboratory processing of PMMA might decrease the surface roughness and consequently the adhesion of S. sanguinis to this material.

  16. Cell fitting to adhesive surfaces: A prerequisite to firm attachment and subsequent events

    Directory of Open Access Journals (Sweden)

    Pierres A.

    2002-06-01

    Full Text Available Cell adhesion usually involves extensive shape reorganization. This process is important because i it is required for efficient cross-linking of interacting surfaces by adhesion receptors the length of which does not exceed several tens of nanometers and ii it influences subsequent cell differentiation and activation. This review focuses on the initial phase of cell deformation, preceding the extensive reorganization process known as spreading. This first phase includes local flattening at the micrometer scale and membrane alignment at the nanometer level, resulting in fitting of the cell to an adhesive surface. Three main points are considered. First, experimental methods available to study cell apposition to a surface are described, with an emphasis on interference reflection microscopy. Second, selected experimental evidence is presented to show that there is a quantitative relationship between "adhesiveness" and "contact extension", and some theoretical models aimed at relating these parameters are briefly sketched. Third, experimental data on the kinetics of initial contact extension are described and possible mechanisms for driving this extension are discussed, including nonspecific forces, receptor-mediated interactions, active cell movements or passive membrane fluctuations. It is concluded that both passive physical phenomena and random active cell movements are possible candidates for the initial triggering of contact extension.

  17. Quantitative characterization of the influence of the nanoscale morphology of nanostructured surfaces on bacterial adhesion and biofilm formation.

    Directory of Open Access Journals (Sweden)

    Ajay Vikram Singh

    Full Text Available Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological

  18. Plasma surface oxidation of 316L stainless steel for improving adhesion strength of silicone rubber coating to metal substrate

    Science.gov (United States)

    Latifi, Afrooz; Imani, Mohammad; Khorasani, Mohammad Taghi; Daliri Joupari, Morteza

    2014-11-01

    Stainless steel 316L is one of the most widely used materials for fabricating of biomedical devices hence, improving its surface properties is still of great interest and challenging in biomaterial sciences. Plasma oxidation, in comparison to the conventional chemical or mechanical methods, is one of the most efficient methods recently used for surface treatment of biomaterials. Here, stainless steel specimens were surface oxidized by radio-frequency plasma irradiation operating at 34 MHz under pure oxygen atmosphere. Surface chemical composition of the samples was significantly changed after plasma oxidation by appearance of the chromium and iron oxides on the plasma-oxidized surface. A wettable surface, possessing high surface energy (83.19 mN m-1), was observed after plasma oxidation. Upon completion of the surface modification process, silicone rubber was spray coated on the plasma-treated stainless steel surface. Morphology of the silicone rubber coating was investigated by scanning electron microscopy (SEM). A uniform coating was formed on the oxidized surface with no delamination at polymer-metal interface. Pull-off tests showed the lowest adhesion strength of coating to substrate (0.12 MPa) for untreated specimens and the highest (0.89 MPa) for plasma-oxidized ones.

  19. Comparison of adhesion of the food spoilage bacterium Shewanella putrefaciens to stainless steel and silver surfaces

    DEFF Research Database (Denmark)

    Hjelm, Mette; Hilbert, Lisbeth Rischel; Møller, Per

    2002-01-01

    The aim of this study is to compare the number of attached bacteria, Shewanella putrefaciens, on stainless steel with different silver surfaces. Thus evaluating if silver surfaces could contribute to a higher hygienic status in the food industry. Bacterial adhesion to three types of silver surfaces...... than one log unit in bacterial numbers on the two types of materials was observed, but for most samples the difference was within one log unit. Treating new silver with sulphide to try to reproduce a tarnished silver surface did not result in a similar lowering of adhering cells when compared to steel...

  20. Effect of different finishing techniques for restorative materials on surface roughness and bacterial adhesion.

    Science.gov (United States)

    Aykent, Filiz; Yondem, Isa; Ozyesil, Atilla G; Gunal, Solen K; Avunduk, Mustafa C; Ozkan, Semiha

    2010-04-01

    The formation of biofilm and bacterial accumulation on dental materials may lead to the development of gingival inflammation and secondary caries. The purpose of this study was to examine the effect of different surface finishing and polishing methods on surface roughness and the adhesion of S. mutans bacteria to 2 new-generation indirect composite resins, 1 direct composite resin, and 1 ceramic material. Forty specimens (10 x 10 x 2 mm) of each material, indirect composite resins (SR Adoro, Estenia), direct composite resin (Tetric), and a ceramic material (VITABLOCS Mark II), were fabricated. Specimens were divided into 4 groups (n=10) that were treated with 1 of the following 4 surface finishing techniques: diamond rotary cutting instrument, sandpaper discs (Sof-Lex), silicone-carbide rubber points (Shofu), or a felt wheel with diamond paste. Surface roughness was measured with a profilometer. Test specimens were covered with artificial saliva and mucin to produce pellicle. Bacterial suspension (10(9) CFU/ml) was then added to the pellicle-coated specimens, and bacterial adhesion was determined using a confocal laser microscope and image analyzing program. Data were analyzed with 2-way ANOVA, followed by Tukey HSD test, Pearson correlation, and regression analysis (alpha=.05). The highest surface roughness values were recorded in SR Adoro and diamond rotary cutting instrument groups. The lowest vital S. mutans adhesion was seen in the ceramic group and in SR Adoro indirect composite resin (Padhesion to indirect composite resin materials differed from that to ceramic material after surface treatments. A positive correlation was observed between surface roughness and the vital S. mutans adhesion. Copyright 2010 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  1. The effect of dentine surface preparation and reduced application time of adhesive on bonding strength.

    Science.gov (United States)

    Saikaew, Pipop; Chowdhury, A F M Almas; Fukuyama, Mai; Kakuda, Shinichi; Carvalho, Ricardo M; Sano, Hidehiko

    2016-04-01

    This study evaluated the effects of surface preparation and the application time of adhesives on the resin-dentine bond strengths with universal adhesives. Sixty molars were cut to exposed mid-coronal dentine and divided into 12 groups (n=5) based on three factors; (1) adhesive: G-Premio Bond (GP, GC Corp., Tokyo, Japan), Clearfil Universal Bond (CU, Kuraray Noritake Dental Inc., Okayama, Japan) and Scotchbond Universal Adhesive (SB, 3M ESPE, St. Paul, MN, USA); (2) smear layer preparation: SiC paper ground dentine or bur-cut dentine; (3) application time: shortened time or as manufacturer's instruction. Fifteen resin-dentine sticks per group were processed for microtensile bond strength test (μTBS) according to non-trimming technique (1mm(2)) after storage in distilled water (37 °C) for 24h. Data were analyzed by three-way ANOVA and Dunnett T3 tests (α=0.05). Fractured surfaces were observed under scanning electron microscope (SEM). Another 12 teeth were prepared and cut into slices for SEM examination of bonded interfaces. μTBS were higher when bonded to SiC-ground dentine according to manufacturer's instruction. Bonding to bur-cut dentine resulted in significantly lower μTBS (padhesive resin interface. This was more pronounced when adhesives were bonded with a reduced application time and on bur cut dentine. The performance of universal adhesives can be compromised on bur cut dentine and when applied with a reduced application time. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. In vitro Candida colonization on acrylic resins and denture liners: influence of surface free energy, roughness, saliva, and adhering bacteria.

    Science.gov (United States)

    Pereira-Cenci, Tatiana; Pereira, Tatiana; Cury, Altair Antoninha Del Bel; Cenci, Maximiliano Sérgio; Rodrigues-Garcia, Renata Cunha Matheus

    2007-01-01

    This study aimed to determine the influence of surface roughness (Ra), surface free energy (SFE), saliva, and bacteria on Candida adhesion to denture materials. The Ra and SFE of 2 acrylic resin specimens and 2 denture liner specimens were measured and assayed in a flow chamber for bacteria culture perfusion plus Candida albicans or C glabrata cultures. Adhesion was determined by counting under light microscopy. Candida adhesion showed significant differences depending on the factors involved. The overall colonization was significantly decreased by saliva and influenced by bacteria. Candida adhesion was strongly affected by Ra, saliva, and bacteria, but not by SFE.

  3. Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Alves, P., E-mail: palves@eq.uc.pt [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Ferreira, P. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Kaiser, Jean-Pierre [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Salk, Natalie [Mikrofertigung – Micro Engineering, Fraunhofer IFAM, Wiener Strasse 12, D-288359 Bremen (Germany); Bruinink, Arie [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Sousa, Hermínio C. de; Gil, M.H. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal)

    2013-10-15

    The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan{sup ®}) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

  4. Divalent cations and the protein surface co-ordinate the intensity of human platelet adhesion and P-selectin surface expression.

    Science.gov (United States)

    Whiss, P A; Andersson, R G G

    2002-07-01

    At sites of blood vessel injury, platelets adhere to exposed vessel components, such as collagen, or immobilized fibrinogen derived from plasma or activated platelets. The divalent cations Mg(2+) and Ca(2+) are essential for platelet adhesion and activation, but Mg(2+) can also inhibit platelet activation. The present study evaluates, by an enzymatic method, the effects of various divalent cations on the adhesion of isolated human platelets to collagen, fibrinogen, albumin or plastic in vitro. By enzyme-linked immunosorbent assay, platelet surface expression of P-selectin was measured to estimate the state of activation on adherence. Mg(2+) increased platelet adhesion exclusively to collagen and fibrinogen at physiologically relevant concentrations. At higher concentrations, the adhesion declined. Ca(2+) induced a weak adhesion only to fibrinogen at physiological doses and a peak of increased adhesion to all protein-coated surfaces at 10 mmol/l. Mn(2+) elicited dose-dependent adhesion only to collagen and fibrinogen. Zn(2+), Ni(2+) and Cu(2+) increased the adhesion of platelets independently of the surface. Ca(2+) dose-dependently inhibited adhesion elicited by Mg(2+) to collagen and fibrinogen. No other combination of divalent cations elicited such an effect. Mg(2+)-dependent platelet adhesion to collagen and Ca(2+)-dependent adhesion to fibrinogen increased P-selectin expression. Thus, the present study shows that the outcome of the platelet adhesion depends on the surface and the access of divalent cations, which co-ordinate the intensity of platelet adhesion and P-selectin surface expression.

  5. Washing-resistant surfactant coated surface is able to inhibit pathogenic bacteria adhesion

    Science.gov (United States)

    Treter, Janine; Bonatto, Fernando; Krug, Cristiano; Soares, Gabriel Vieira; Baumvol, Israel Jacob Rabin; Macedo, Alexandre José

    2014-06-01

    Surface-active substances, which are able to organize themselves spontaneously on surfaces, triggering changes in the nature of the solid-liquid interface, are likely to influence microorganism adhesion and biofilm formation. Therefore, this study aimed to evaluate chemical non-ionic surfactants activity against pathogenic microbial biofilms and to cover biomaterial surfaces in order to obtain an anti-infective surface. After testing 11 different surfactants, Pluronic F127 was selected for further studies due to its non-biocidal properties and capability to inhibit up to 90% of biofilm formation of Gram-positive pathogen and its clinical isolates. The coating technique using direct impregnation on the surface showed important antibiofilm formation characteristics, even after extensive washes. Surface roughness and bacterial surface polarity does not influence the adhesion of Staphylococcus epidermidis, however, the material coated surface became extremely hydrophilic. The phenotype of S. epidermidis does not seem to have been affected by the contact with surfactant, reinforcing the evidence that a physical phenomenon is responsible for the activity. This paper presents a simple method of surface coating employing a synthetic surfactant to prevent S. epidermidis biofilm formation.

  6. Elastic-plastic adhesive contact of rough surfaces using n-point asperity model

    International Nuclear Information System (INIS)

    Sahoo, Prasanta; Mitra, Anirban; Saha, Kashinath

    2009-01-01

    This study considers an analysis of the elastic-plastic contact of rough surfaces in the presence of adhesion using an n-point asperity model. The multiple-point asperity model, developed by Hariri et al (2006 Trans ASME: J. Tribol. 128 505-14) is integrated into the elastic-plastic adhesive contact model developed by Roy Chowdhury and Ghosh (1994 Wear 174 9-19). This n-point asperity model differs from the conventional Greenwood and Williamson model (1966 Proc. R. Soc. Lond. A 295 300-19) in considering the asperities not as fixed entities but as those that change through the contact process, and hence it represents the asperities in a more realistic manner. The newly defined adhesion index and plasticity index defined for the n-point asperity model are used to consider the different conditions that arise because of varying load, surface and material parameters. A comparison between the load-separation behaviour of the new model and the conventional one shows a significant difference between the two depending on combinations of mean separation, adhesion index and plasticity index.

  7. Influence of roughness of machined surface on adhesion of anticorrosion system

    Directory of Open Access Journals (Sweden)

    Jiří Votava

    2013-01-01

    Full Text Available The goal of this experiment is to analyse dependence of roughness of machined surface on adhesion performance of various anticorrosion systems. In order to prepare samples for the experiment, samples were milled on a knee and column type of a horizontal milling machine. Depending on cutting conditions and machining tool, there were set intervals of roughness of machined surface which are commonly achievable on this type of machine. It is a roughness in the interval of 0.4–1.6 µm (finishing, 1.6–6.3 µm (standard milling a 6.3–12.5 µm (roughening. Removable cutting tips were used as a machining tool and for roughening, a shell end milling cutter NAREX 63x40 HSS 90 was used. Three types of anticorrosion systems were used in order to analyse the adhesion, that is a water-thinnable system Eternal, synthetic single layer coating Hostagrund and a duplex system, whose first layer is formed by dipped zinc and a top layer by a single-layer acrylate system Zinorex. Testing of the influence of surface roughness (anchoring system on adhesion of the individual anticorrosion systems were processed in compliance with the norm ČSN EN ISO 4624, a tearing test. The main criterion of adhesion of anticorrosion system is defined as a power which needed for tear-off testing object stuck to a tested sample. This analysis was processed also during the corrosion test in the salt spray environment according to the norm ČSN EN ISO 9227. In order to better identify the adhesion of the individual anticorrosion systems, the analysis of undercorrosion according to the norm ISO 4628-8 was processed.

  8. Energy conservation potential of surface modification technologies

    Energy Technology Data Exchange (ETDEWEB)

    Le, H.K.; Horne, D.M.; Silberglitt, R.S.

    1985-09-01

    This report assesses the energy conservation impact of surface modification technologies on the metalworking industries. The energy conservation impact of surface modification technologies on the metalworking industries is assessed by estimating their friction and wear tribological sinks and the subsequent reduction in these sinks when surface modified tools are used. Ion implantation, coatings, and laser and electron beam surface modifications are considered.

  9. Effect of growth time on the surface and adhesion properties of Lactobacillus rhamnosus GG.

    Science.gov (United States)

    Deepika, G; Green, R J; Frazier, R A; Charalampopoulos, D

    2009-10-01

    To investigate the changes in the surface properties of Lactobacillus rhamnosus GG during growth, and relate them with the ability of the Lactobacillus cells to adhere to Caco-2 cells. Lactobacillus rhamnosus GG was grown in complex medium, and cell samples taken at four time points and freeze dried. Untreated and trypsin treated freeze dried samples were analysed for their composition using SDS-PAGE analysis and Fourier transform infrared spectroscopy (FTIR), hydrophobicity and zeta potential, and for their ability to adhere to Caco-2 cells. The results suggested that in the case of early exponential phase samples (4 and 8 h), the net surface properties, i.e. hydrophobicity and charge, were determined to a large extent by anionic hydrophilic components, whereas in the case of stationary phase samples (13 and 26 h), hydrophobic proteins seemed to play the biggest role. Considerable differences were also observed between the ability of the different samples to adhere to Caco-2 cells; maximum adhesion was observed for the early stationary phase sample (13 h). The results suggested that the adhesion to Caco-2 cells was influenced by both proteins and non-proteinaceous compounds present on the surface of the Lactobacillus cells. The surface properties of Lact. rhamnosus GG changed during growth, which in return affected the ability of the Lactobacillus cells to adhere to Caco-2 cells. The levels of adhesion of Lactobacillus cells to Caco-2 cells were influenced by the growth time and reflected changes on the bacterial surface. This study provides critical information on the physicochemical factors that influence bacterial adhesion to intestinal cells.

  10. Surface Coating of Gypsum-Based Molds for Maxillofacial Prosthetic Silicone Elastomeric Material: Evaluating Different Microbial Adhesion.

    Science.gov (United States)

    Khalaf, Salah; Ariffin, Zaihan; Husein, Adam; Reza, Fazal

    2017-12-01

    To compare the adhesion of three microorganisms on modified and unmodified silicone elastomer surfaces with different surface roughnesses and porosities. Candida albicans, Streptococcus mutans, and Staphylococcus aureus were incubated with modified and unmodified silicone groups (N = 35) for 30 days at 37°C. The counts of viable microorganisms in the accumulating biofilm layer were determined and converted to cfu/cm 2 unit surface area. A scanning electron microscope (SEM) was used to evaluate the microbial adhesion. Statistical analysis was performed using t-test, one-way ANOVA, and post hoc tests as indicated. Significant differences in microbial adhesion were observed between modified and unmodified silicone elastomers after the cells were incubated for 30 days (p silicone elastomer compared with unmodified silicone elastomer. Surface modification of silicone elastomer yielding a smoother and less porous surface showed lower adhesion of different microorganisms than observed on unmodified surfaces. © 2017 by the American College of Prosthodontists.

  11. Platelet adhesion and cellular interaction with poly(ethylene oxide) immobilized onto silicone rubber membrane surfaces.

    Science.gov (United States)

    Hsiue, G H; Lee, S D; Chang, P C

    1996-01-01

    Cellular interaction and platelet adsorption were investigated on poly(ethylene oxide) (PEO) immobilized silicone rubber membrane (SR) which has polyacrylic acid grafts on the surfaces. Polyacrylic acid (PAA) had been introduced to the SR surface after Ar plasma treatment of SR surfaces to introduce peroxide groups. Surface characterizations were made using ATR-FTIR, ESCA, SEM, and contact angle measurements. Experimental results obtained by ESCA high resolution curve fitting spectra indicated that the amount of bisamino PEO of different molecular weights immobilized onto SR surfaces were similar, which showed that the influence of the length of molecular chains (-C-C-O-) on the reactivity of terminal amino group is negligible. The wettability of modified SR surfaces increased with an increase in PEO molecular weight. Biological studies such as corneal epithelial cell culture and blood platelet adhesion were performed to understand the biocompatibility of modified SR surfaces. Biological studies using corneal epithelial cells showed that cell migration, attachment and proliferation onto PEO-20000 immobilized SR surface were suppressed, whereas these biological activities on PEO-600 were enhanced. Another study on platelet adhesion revealed that many platelets attached to PEO-600 immobilized SR, while platelet deposition was rarely observed on SR grafted with PEO-3350. The effects of different PEO molecular chains on biological response were discussed.

  12. Biomimetic superhydrophobic surface of high adhesion fabricated with micronano binary structure on aluminum alloy.

    Science.gov (United States)

    Liu, Yan; Liu, Jindan; Li, Shuyi; Liu, Jiaan; Han, Zhiwu; Ren, Luquan

    2013-09-25

    Triggered by the microstructure characteristics of the surfaces of typical plant leaves such as the petals of red roses, a biomimetic superhydrophobic surface with high adhesion is successfully fabricated on aluminum alloy. The essential procedure is that samples were processed by a laser, then immersed and etched in nitric acid and copper nitrate, and finally modified by DTS (CH3(CH2)11Si(OCH3)3). The obtained surfaces exhibit a binary structure consisting of microscale crater-like pits and nanoscale reticula. The superhydrophobicity can be simultaneously affected by the micronano binary structure and chemical composition of the surface. The contact angle of the superhydrophobic surface reaches up to 158.8 ± 2°. Especially, the surface with micronano binary structure is revealed to be an excellent adhesive property with petal-effect. Moreover, the superhydrophobic surfaces show excellent stability in aqueous solution with a large pH range and after being exposed long-term in air. In this way, the multifunctional biomimetic structural surface of the aluminum alloy is fabricated. Furthermore, the preparation technology in this article provides a new route for other metal materials.

  13. Rapid transfer of hierarchical microstructures onto biomimetic polymer surfaces with gradually tunable water adhesion from slippery to sticky superhydrophobicity

    Science.gov (United States)

    Chen, An-Fu; Huang, Han-Xiong

    2016-02-01

    Biomimetic superhydrophobic surfaces are generally limited to extremely high or quite low water droplet adhesion. The present work proposes flexible template replication methods for bio-inspired polypropylene (PP) surfaces with microtopographies and gradually tunable water droplet adhesion in one step using microinjection compression molding (μ-ICM). A dual-level microstructure appears on PP surfaces prepared using a flexible template. The microstructures obtained under low and high mold temperatures exhibit low-aspect-ratio (AR) micropillars with semi-spherical top and high-AR ones with conical top, resulting in the surfaces with high-adhesive hydrophobicity and low-adhesive superhydrophobicity, respectively. Further, silica nanoparticles (SNPs) coated on templates are transferred to viscous state-dominated melt during its filling in μ-ICM, and firmly adhered to the skin of the replicas, forming hierarchical microstructures on PP surfaces. The hydrophilic and hydrophobic SNPs on high-AR micropillared surfaces help achieve extremely high (petal effect) and extremely low (lotus effect) adhesion on superhydrophobic surfaces, respectively. The hybrid SNPs on low-AR micropillars change the Wenzel state-dominated surface to Cassie-Baxter state-dominated surface and preserves medium adhesion with superhydrophobicity. The proposed methods for fast and mass replication of superhydrophobic surfaces with the dual-level or hierarchical microtopography can be excellent candidates for the development of microfluidics, sensors, and labs on chip.

  14. Surface adhesion study of La2O3 thin film on Si and glass substrate for micro-flexography printing

    Science.gov (United States)

    Hassan, S.; Yusof, M. S.; Embong, Z.; Maksud, M. I.

    2017-01-01

    Adhesive property can be described as an interchangeably with some ink and substance which was applied to one surface of two separate items that bonded together. Lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent or printing ink. This metal deposit was embedded on Silica (Si) wafer and glass substrate using Magnetron Sputtering technique. The choose of Lanthanum oxide as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer and glass substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). This research will focus on 3 narrow scan regions which are C 1s, O 1s and La 3d. Further discussion of the spectrum evaluation will be discussed in detail. Here, it is proposed that from the adhesive and surface chemical properties of La is the best on glass substrate which suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal in a practice of micro-flexography printing.

  15. Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law

    Science.gov (United States)

    Zhu, Xinyao; Xu, Wei

    2018-02-01

    The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.

  16. Evaluation of Ti-6Al-4V surface treatments for use with a polyphenylquinoxaline adhesive

    Science.gov (United States)

    Progar, Donald J.

    1987-01-01

    Three surface treatments for Ti-6Al-4V adherends were evaluated using a thermoplastic polymer monoether polyphenylquinoxaline, MEPPQ, which had been shown in previous studies to have good potential as a high temperature adhesive for aerospace applications. Initial results based on long term thermal exposure at 232 C (450 F) using the phosphate-fluoride (PF) and chromic acid anodized (CAA) treatments with MEPPQ adhesive were not encouraging. A significant improvement in strength retention and a change in failure mode (cohesive) at 232 C (450 F) was found for the SHA treated specimens compared to the PF and CAA treatments. Although an improvement in long term thermal durability was obtained with the SHA treatment of Ti-6Al-4V, an improved surface treatment with better long term durability is still required for aerospace applications.

  17. Adhesion of MRC-5 and A549 cells on poly(dimethylsiloxane) surface modified by proteins.

    Science.gov (United States)

    Zuchowska, Agnieszka; Kwiatkowski, Piotr; Jastrzebska, Elzbieta; Chudy, Michal; Dybko, Artur; Brzozka, Zbigniew

    2016-02-01

    PDMS is a very popular material used for fabrication of Lab-on-a-Chip systems for biological applications. Although PDMS has numerous advantages, it is a highly hydrophobic material, which inhibits adhesion and proliferation of the cells. PDMS surface modifications are used to enrich growth of the cells. However, due to the fact that each cell type has specific adhesion, it is necessary to optimize the parameters of these modifications. In this paper, we present an investigation of normal (MRC-5) and carcinoma (A549) human lung cell adhesion and proliferation on modified PDMS surfaces. We have chosen these cell types because often they are used as models for basic cancer research. To the best of our knowledge, this is the first presentation of this type of investigation. The combination of a gas-phase processing (oxygen plasma or ultraviolet irradiation) and wet chemical methods based on proteins' adsorption was used in our experiments. Different proteins such as poly-l-lysine, fibronectin, laminin, gelatin, and collagen were incubated with the activated PDMS samples. To compare with other works, here, we also examined how ratio of prepolymer to curing agent (5:1, 10:1, and 20:1) influences PDMS hydrophilicity during further modifications. The highest adhesion of the tested cells was observed for the usage of collagen, regardless of PDMS ratio. However, the MRC-5 cell line demonstrated better adhesion than A549 cells. This is probably due to the difference in their morphology and type (normal/cancer). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Facile Adhesion-Tuning of Superhydrophobic Surfaces between "Lotus" and "Petal" Effect and Their Influence on Icing and Deicing Properties.

    Science.gov (United States)

    Nine, Md J; Tung, Tran Thanh; Alotaibi, Faisal; Tran, Diana N H; Losic, Dusan

    2017-03-08

    Adhesion behavior of superhydrophobic (SH) surfaces is an active research field related to various engineering applications in controlled microdroplet transportation, self-cleaning, deicing, biochemical separation, tissue engineering, and water harvesting. Herein, we report a facile approach to control droplet adhesion, bouncing and rolling on properties of SH surfaces by tuning their air-gap and roughness-height by altering the concentrations of poly dimethyl-siloxane (PDMS). The optimal use of PDMS (4-16 wt %) in a dual-scale (nano- and microparticles) composite enables control of the specific surface area (SSA), pore volume, and roughness of matrices that result in a well-controlled adhesion between water droplets and SH surfaces. The sliding angles of these surfaces were tuned to be varied between 2 ± 1 and 87 ± 2°, which are attributed to the transformation of the contact type between droplet and surface from "point contact" to "area contact". We further explored the effectiveness of these low and high adhesive SH surfaces in icing and deicing actions, which provides a new insight into design highly efficient and low-cost ice-release surface for cold temperature applications. Low adhesion (lotus effect) surface with higher pore-volume exhibited relatively excellent ice-release properties with significant icing delay ability principally attributed to the large air gap in the coating matrix than SH matrix with high adhesion (petal effect).

  19. Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Ramazani, S.A. Ahmad, E-mail: Ramazani@sharif.ir [Polymer Group, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mousavi, Seyyed Abbas, E-mail: Musavi@che.sharif.ir [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Seyedjafari, Ehsan [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of); Poursalehi, Reza [Department of Physics, University of Shahed, Tehran (Iran, Islamic Republic of); Sareh, Shohreh [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Silakhori, Kaveh [Laser Research Center, Atomic Energy Organization, Tehran (Iran, Islamic Republic of); Poorfatollah, Ali Akbar [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Shamkhali, Amir Nasser [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

    2009-05-05

    Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after treatment. The results obtained from this test showed that after laser treatment, the cells were attached and proliferated extensively on the Nd:YAG laser treated films in comparison with the unmodified PC. Moreover, it was revealed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface. The obtained results also showed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface.

  20. Friction and Adhesion Forces of Bacillus thuringiensis Spores on Planar Surfaces in Atmospheric Systems

    Energy Technology Data Exchange (ETDEWEB)

    Kweon, Hyojin [Georgia Inst. of Technology, Atlanta, GA (United States); Yiacoumi, Sotira [Georgia Inst. of Technology, Atlanta, GA (United States); Tsouris, Costas [Georgia Inst. of Technology, Atlanta, GA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2011-11-07

    The kinetic friction force and the adhesion force of Bacillus thuringiensis spores on planar surfaces in atmospheric systems were studied using atomic force microscopy. The influence of relative humidity (RH) on these forces varied for different surface properties including hydrophobicity, roughness, and surface charge. The friction force of the spore was greater on a rougher surface than on mica, which is atomically flat. As RH increases, the friction force of the spores decreases on mica whereas it increases on rough surfaces. The influence of RH on the interaction forces between hydrophobic surfaces is not as strong as for hydrophilic surfaces. The friction force of the spore is linear to the sum of the adhesion force and normal load on the hydrophobic surface. In conclusion, the poorly defined surface structure of the spore and the adsorption of contaminants from the surrounding atmosphere are believed to cause a discrepancy between the calculated and measured adhesion forces.

  1. Effect of surface modification of fiber post using dopamine polymerization on interfacial adhesion with core resin

    Science.gov (United States)

    Li, Yan; Chen, Qian; Yi, Mi; Zhou, Xuegang; Wang, Xinzhi; Cai, Qing; Yang, Xiaoping

    2013-06-01

    The purpose of this study is to evaluate the effects of surface modification of fiber posts using dopamine polymerization on their interfacial adhesion with core resins. The fiber posts were surface-coated with polydopamine via the oxidization polymerization of dopamine in aqueous solution. Two commercial composite resins (3M ESPE and paracore) were used to build up the cores around the post heads (modified and unmodified). Pull-out tests were conducted, and the maximum failure load (N) and the failure modes were recorded to compare the interfacial adhesion between fiber post and resin core. The results demonstrated that the tensile forces needed to damage the retention of fiber post increased from 228.6 ± 10.9 N to 276.3 ± 14.7 N in the 3M ESPE group, from 216.5 ± 17.4 N to 277.2 ± 14.3 N in the paracore group, when polydopamine-coated fiber posts were applied. No significant difference had been found between the different resin groups. The observation of the surface morphology of both fiber posts and cores after adhesive failure clearly confirmed that the presence of polydopamine interlayer had acted as a binder to bond fiber post and resin together. This study would be valuable for endodontically treatments to reduce the chances of detachment of resin core from the fiber post or dislodgement of fiber posts from the canal.

  2. Green tea polyphenol tailors cell adhesivity of RGD displaying surfaces: multicomponent models monitored optically

    Science.gov (United States)

    Peter, Beatrix; Farkas, Eniko; Forgacs, Eniko; Saftics, Andras; Kovacs, Boglarka; Kurunczi, Sandor; Szekacs, Inna; Csampai, Antal; Bosze, Szilvia; Horvath, Robert

    2017-02-01

    The interaction of the anti-adhesive coating, poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its Arg-Gly-Asp (RGD) functionalized form, PLL-g-PEG-RGD, with the green tea polyphenol, epigallocatechin-gallate (EGCg) was in situ monitored. After, the kinetics of cellular adhesion on the EGCg exposed coatings were recorded in real-time. The employed plate-based waveguide biosensor is applicable to monitor small molecule binding and sensitive to sub-nanometer scale changes in cell membrane position and cell mass distribution; while detecting the signals of thousands of adhering cells. The combination of this remarkable sensitivity and throughput opens up new avenues in testing complicated models of cell-surface interactions. The systematic studies revealed that, despite the reported excellent antifouling properties of the coatings, EGCg strongly interacted with them, and affected their cell adhesivity in a concentration dependent manner. Moreover, the differences between the effects of the fresh and oxidized EGCg solutions were first demonstrated. Using a semiempirical quantumchemical method we showed that EGCg binds to the PEG chains of PLL-g-PEG-RGD and effectively blocks the RGD sites by hydrogen bonds. The calculations supported the experimental finding that the binding is stronger for the oxidative products. Our work lead to a new model of polyphenol action on cell adhesion ligand accessibility and matrix rigidity.

  3. Adsorption of Amorphous Silica Nanoparticles onto Hydroxyapatite Surfaces Differentially Alters Surfaces Properties and Adhesion of Human Osteoblast Cells.

    Directory of Open Access Journals (Sweden)

    Priya Kalia

    Full Text Available Silicon (Si is suggested to be an important/essential nutrient for bone and connective tissue health. Silicon-substituted hydroxyapatite (Si-HA has silicate ions incorporated into its lattice structure and was developed to improve attachment to bone and increase new bone formation. Here we investigated the direct adsorption of silicate species onto an HA coated surface as a cost effective method of incorporating silicon on to HA surfaces for improved implant osseointegration, and determined changes in surface characteristics and osteoblast cell adhesion. Plasma-sprayed HA-coated stainless steel discs were incubated in silica dispersions of different concentrations (0-42 mM Si, at neutral pH for 12 h. Adsorbed Si was confirmed by XPS analysis and quantified by ICP-OES analysis following release from the HA surface. Changes in surface characteristics were determined by AFM and measurement of surface wettability. Osteoblast cell adhesion was determined by vinculin plaque staining. Maximum Si adsorption to the HA coated disc occurred after incubation in the 6 mM silica dispersion and decreased progressively with higher silica concentrations, while no adsorption was observed with dispersions below 6 mM Si. Comparison of the Si dispersions that produced the highest and lowest Si adsorption to the HA surface, by TEM-based analysis, revealed an abundance of small amorphous nanosilica species (NSP of ~1.5 nm in diameter in the 6 mM Si dispersion, with much fewer and larger NSP in the 42 mM Si dispersions. 29Si-NMR confirmed that the NSPs in the 6 mM silica dispersion were polymeric and similar in composition to the larger NSPs in the 42 mM Si dispersion, suggesting that the latter were aggregates of the former. Amorphous NSP adsorbed from the 6 mM dispersion on to a HA-coated disc surface increased the surface's water contact angle by 53°, whereas that adsorbed from the 42 mM dispersion decreased the contact angle by 18°, indicating increased and

  4. How wood adhesives work and where are the areas for improvement

    Science.gov (United States)

    Charles R. Frihart

    2013-01-01

    Invoking normal adhesion theory, bonding of wood would seem to be easy in that the surface has plenty of roughness for mechanical interlocking with high enough surface energy, there is an abundance of hydroxyl groups on the wood for hydrogen bonding to the adhesives, and the aqueous solvent in the adhesive can readily soak into the wood. In fact most adhesives will...

  5. Fabrication of low adhesive superhydrophobic surfaces using nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited electro-brush plating

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tianchi [College of Mechanical & Electrical Engineering, Xu Zhou 221116 (China); Ge, Shirong [College of Mechanical & Electrical Engineering, Xu Zhou 221116 (China); College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China); Liu, Hongtao, E-mail: liuht100@126.com [College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China); Sun, Qinghe; Zhu, Wei; Yan, Wei; Qi, Jianwei [College of Materials Science and Engineering, China University of Mining and Technology, Xu Zhou 221116 (China)

    2015-11-30

    Highlights: • We fabricate a low adhesive superhydrophobic nano Cu/Al{sub 2}O{sub 3} composited Ni–Cr coating via brush plating. • We investigate the influence of process parameters on hydrophobic properties process. • We discuss the formation mechanism of structures on the surface and using water rebound height to explain the low adhesive force mechanism. - Abstract: Superhydrophobic nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited coating with a low adhesive force was deposited onto the Q345 carbon steel via electro-brush plating. Surface morphologies of nano Cu/Al{sub 2}O{sub 3} Ni–Cr composited coating were investigated by scanning electron microscope (SEM). Chemical compositions were characterized by energy dispersive spectroscopy (EDS). First of all, by adjusting different process parameters such as working voltage, relative velocity, Cu particles concentration and plating time, we obtain the most optimal parameters: working voltage is 15 V, relative velocity is 4.8 m/min, Cu particles concentration is 5 g/L and plating time is 60 s. Under the best process parameters, the water contact angle reaches to 156° and a sliding angle is less than 2° on the nano Cu/Al{sub 2}O{sub 3} Ni–Cr coating. Then the mechanism of the superhydrophobic and low adhesion characteristic of this surface were explained by Cassie's model. Low adhesive force can be characterized by max rebound height of water droplet. As a result, to achieve low adhesive surface it is necessary to decrease the fraction of the solid/liquid interface under the water droplet. Finally the coating was proved to have an excellent self-cleaning performance.

  6. Tunable surface wettability and water adhesion of Sb2S3 micro-/nanorod films

    International Nuclear Information System (INIS)

    Zhong, Xin; Zhao, Huiping; Yang, Hao; Liu, Yunling; Yan, Guoping; Chen, Rong

    2014-01-01

    Antimony sulfide (Sb 2 S 3 ) films were successfully prepared by spin coating Sb 2 S 3 micro-/nanorods with different sizes on glass slides, which was synthesized via a facile and rapid microwave irradiation method. The prepared Sb 2 S 3 micro-/nanorods and films were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and water contact angle (CA). The as-prepared Sb 2 S 3 films exhibited different surface wettabilities ranging from superhydrophilicity to superhydrophobicity, which was strongly dependent on the diameter of Sb 2 S 3 micro-/nanorod. Sb 2 S 3 film made by nanorods possessed superhydrophobic surface and high water adhesive property. After surface modification with stearic acid, the superhydrophobic surface exhibited an excellent self-cleaning property owing to its low adhesive force. The clarification of three possible states including Wenzel's state, “Gecko” state and Cassie's state for Sb 2 S 3 film surfaces was also proposed to provide a better understanding of interesting surface phenomena on Sb 2 S 3 films.

  7. Influence of substrate modulus on gecko adhesion

    Science.gov (United States)

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-03-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

  8. Anti-adhesion effects of liquid-infused textured surfaces on high-temperature stainless steel for soft tissue

    Science.gov (United States)

    Zhang, Pengfei; Chen, Huawei; Zhang, Liwen; Zhang, Deyuan

    2016-11-01

    Soft tissue adhesion on the electrosurgical instruments can induce many serious complications, such as failure of hemostasis and damage to the surrounding soft tissue. The soft tissue adhesion is mainly caused by the high temperature on the instrument surface generally made of stainless steel. Nepenthes inspired liquid-infused surfaces (LIS), highly promising for anti-adhesion, have attracted considerable interests. In this paper, we investigated the anti-adhesion effects of LIS on high-temperature stainless steel for soft tissue for the first time, aiming to develop a new approach to solve the soft tissue adhesion problem. The textured surface, acting as the holding structures, was fabricated by photolithography-assisted chemical etching. Silicone oil, with good biocompatibility and high-temperature resistance, was chosen as the infused liquid. The adhesion force measurements for soft tissue on the LIS at high temperatures indicated that the soft tissue adhesion force was decreased by approximately 80% at 250 °C. Besides, the cycle tests of soft tissue adhesion force demonstrated the excellent stability of prepared LIS. We anticipate that LIS will be of great promise for practical applications on the electrosurgical instruments.

  9. Potential energy surfaces for chemical reactions

    International Nuclear Information System (INIS)

    Schaefer, H.F. III.

    1976-01-01

    Research into potential energy surfaces for chemical reactions at Lawrence Berkeley Laboratory during 1976 is described. Topics covered include: the fuzzy interface between surface chemistry catalysis and organometallic chemistry; potential energy surfaces for elementary fluorine hydrogen reactions; structure, energetics, and reactivity of carbenes; and the theory of self-consistent electron pairs

  10. Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane

    Directory of Open Access Journals (Sweden)

    Rogerio Amaral Tupinambá

    Full Text Available ABSTRACT Introduction: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods: Hexamethyldisiloxane (HMDSO polymer films were deposited on conventional (n = 10 and self-ligating (n = 10 stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results: Significant statistical differences (p 0.05. Conclusion: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film.

  11. Bacterial adhesion on conventional and self-ligating metallic brackets after surface treatment with plasma-polymerized hexamethyldisiloxane

    Science.gov (United States)

    Tupinambá, Rogerio Amaral; Claro, Cristiane Aparecida de Assis; Pereira, Cristiane Aparecida; Nobrega, Celestino José Prudente; Claro, Ana Paula Rosifini Alves

    2017-01-01

    ABSTRACT Introduction: Plasma-polymerized film deposition was created to modify metallic orthodontic brackets surface properties in order to inhibit bacterial adhesion. Methods: Hexamethyldisiloxane (HMDSO) polymer films were deposited on conventional (n = 10) and self-ligating (n = 10) stainless steel orthodontic brackets using the Plasma-Enhanced Chemical Vapor Deposition (PECVD) radio frequency technique. The samples were divided into two groups according to the kind of bracket and two subgroups after surface treatment. Scanning Electron Microscopy (SEM) analysis was performed to assess the presence of bacterial adhesion over samples surfaces (slot and wings region) and film layer integrity. Surface roughness was assessed by Confocal Interferometry (CI) and surface wettability, by goniometry. For bacterial adhesion analysis, samples were exposed for 72 hours to a Streptococcus mutans solution for biofilm formation. The values obtained for surface roughness were analyzed using the Mann-Whitney test while biofilm adhesion were assessed by Kruskal-Wallis and SNK test. Results: Significant statistical differences (p 0.05). Conclusion: Plasma-polymerized film deposition was only effective on reducing surface roughness and bacterial adhesion in conventional brackets. It was also noted that conventional brackets showed lower biofilm adhesion than self-ligating brackets despite the absence of film. PMID:28902253

  12. Chemical functionalization of ceramic tile surfaces by silane coupling agents: polymer modified mortar adhesion mechanism implications

    Directory of Open Access Journals (Sweden)

    Alexandra Ancelmo Piscitelli Mansur

    2008-09-01

    Full Text Available Adhesion between tiles and mortars are crucial to the stability of ceramic tile systems. From the chemical point of view, weak forces such as van der Waals forces and hydrophilic interactions are expected to be developed preferably at the tiles and polymer modified Portland cement mortar interface. The main goal of this paper was to use organosilanes as primers to modify ceramic tile hydrophilic properties to improve adhesion between ceramic tiles and polymer modified mortars. Glass tile surfaces were treated with several silane derivatives bearing specific functionalities. Contact angle measurements and Fourier Transform Infrared Spectroscopy (FTIR were used for evaluating the chemical changes on the tile surface. In addition, pull-off tests were conducted to assess the effect on adhesion properties between tile and poly(ethylene-co-vinyl acetate, EVA, modified mortar. The bond strength results have clearly shown the improvement of adherence at the tile-polymer modified mortar interface, reflecting the overall balance of silane, cement and polymer interactions.

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

    Science.gov (United States)

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

    2016-05-18

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

  14. Adhesion and friction in polymer films on solid substrates: conformal sites analysis and corresponding surface measurements.

    Science.gov (United States)

    An, Rong; Huang, Liangliang; Mineart, Kenneth P; Dong, Yihui; Spontak, Richard J; Gubbins, Keith E

    2017-05-21

    In this work, we present a statistical mechanical analysis to elucidate the molecular-level factors responsible for the static and dynamic properties of polymer films. This analysis, which we term conformal sites theory, establishes that three dimensionless parameters play important roles in determining differences from bulk behavior for thin polymer films near to surfaces: a microscopic wetting parameter, α wx , defined as the ratio of polymer-substrate interaction to polymer-polymer interaction; a dimensionless film thickness, H*; and dimensionless temperature, T*. The parameter α wx introduced here provides a more fundamental measure of wetting than previous metrics, since it is defined in terms of intermolecular forces and the atomic structure of the substrate, and so is valid at the nanoscale for gas, liquid or solid films. To test this theoretical analysis, we also report atomic force microscopy measurements of the friction coefficient (μ), adhesion force (F A ) and glass transition temperature (T g ) for thin films of two polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on two planar substrates, graphite and silica. Both the friction coefficient and the glass transition temperature are found to increase as the film thickness decreases, and this increase is more pronounced for the graphite than for the silica surface. The adhesion force is also greater for the graphite surface. The larger effects encountered for the graphite surface are attributed to the fact that the microscopic wetting parameter, α wx , is larger for graphite than for silica, indicating stronger attraction of polymer chains to the graphite surface.

  15. Effect of Enamel and Dentin Surface Treatment on the Self-Adhesive Resin Cement Bond Strength.

    Science.gov (United States)

    Mushashe, Amanda Mahmmad; Gonzaga, Carla Castiglia; Cunha, Leonardo Fernandes da; Furuse, Adilson Yoshio; Moro, Alexandre; Correr, Gisele Maria

    2016-01-01

    The aim of this study was to evaluate the effect of enamel and dentin surface treatment on the micro-shear bond strength of self-adhesive cement. Seventy-two extracted third molars had their crowns embedded in acrylic resin and worn to obtain a flat enamel or dentin surface. The enamel and dentin specimens were randomly assigned to 8 groups (n=12) that were based on surface treatment (11.5% polyacrylic acid solution or no treatment), substrate condition (wet or dry) and storage period (1 day or 90 days), and treated accordingly. Cylinders (1 × 1 mm) were fabricated using self-adhesive resin cement (RelyX U200) following the manufacturer's instructions. The specimens were stored in distilled water at 37 °C for either 1 day or 90 days and subjected to micro-shear bond strength test (EMIC DL 2000 at 0.5 mm/min). After this, the failure type of the specimens was determined. Data were subjected to statistical analysis (a=0.05). According to the results, the 11.5% polyacrylic acid application decreased the bond strength in both enamel and dentin samples. The moist groups showed higher bond strength than the dry ones, regardless of the substrate and surface treatment. Storage period did not influence bond strength. In conclusion, surface treatment with 11.5% polyacrylic acid and absence of moisture decreased the bond strength of the resin-cement (RelyU200), regardless of the storage period.

  16. Mussel-inspired human gelatin nanocoating for creating biologically adhesive surfaces

    Directory of Open Access Journals (Sweden)

    Yang X

    2014-05-01

    Full Text Available Xi Yang,1,2 Liping Zhu,1 Seiichi Tada,1 Di Zhou,3 Takashi Kitajima,1 Takashi Isoshima,1 Yasuhiro Yoshida,1,4 Mariko Nakamura,1,5 Weiqun Yan,2 Yoshihiro Ito1,3 1Nano Medical Engineering Laboratory, RIKEN, Saitama, Japan; 2School of Pharmaceutical Sciences, Jilin University, Jilin, People’s Republic of China; 3Emergent Bioengineering Materials Research Team, RIKEN Center for Emergent Matter Science, Saitama, 4Department of Biomaterials and Bioengineering, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, 5Dental Hygiene Program, Kibi International College, Okayama, Japan Abstract: Recombinant human gelatin was conjugated with dopamine using carbodiimide as a surface modifier. This dopamine-coupled human gelatin (D-rhG was characterized by 1H-nuclear magnetic resonance, mass spectroscopy, and circular dichroism. D-rhG-coated surface properties were analyzed by physicochemical methods. Additionally, cell attachment and growth on the modified surfaces was assessed using human umbilical endothelial cells. Binding of gelatin onto titanium was significantly enhanced by dopamine conjugation. The thickness of the D-rhG coating depended on the treatment pH; thicker layers were formed at higher pH values, with a maximum thickness of 30 nm. D-rhG enhanced the binding of collagen-binding vascular endothelial growth factor and cell adhesion as compared with gelatin alone, even at the same surface concentration. The D-rhG surface modifier enhanced substrate binding by creating an adhesive nanointerface that increased specific protein binding and cell attachment. Keywords: recombinant human gelatin, dopamine, natural catechols, cell adhesion, cell culture, titanium

  17. Cellular automaton simulation of the diffusive motion of bacteria and their adhesion to nanostructures on a solid surface.

    Science.gov (United States)

    Yamamoto, Takehiro; Emura, Chie; Oya, Masashi

    2016-12-01

    The growth of a biofilm begins with the adhesion of bacteria to a solid surface. Consequently, biofilm growth can be managed by the control of bacterial adhesion. Recent experimental studies have suggested that bacterial adhesion can be controlled by modifying a solid surface using nanostructures. Computational prediction and analysis of bacterial adhesion behavior are expected to be useful for the design of effective arrangements of nanostructures for controlling bacterial adhesion. The present study developed a cellular automaton (CA) model for bacterial adhesion simulation that could describe both the diffusive motion of bacteria and dependence of their adhesion patterns on the distance between nanostructures observed in experimental studies. The diffusive motion was analyzed by the moment scaling spectrum theory, and the present model was confirmed to describe subdiffusion behavior due to obstacles. Adhesion patterns observed in experimental studies can be successfully simulated by introducing CA rules to describe a mechanism by which bacteria tend to move to increase the area of contact with nanostructures. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Influence of silane surface modification of veneer on interfacial adhesion of wood-plastic plywood

    Science.gov (United States)

    Fang, Lu; Chang, Liang; Guo, Wen-jing; Chen, Yongping; Wang, Zheng

    2014-01-01

    In this study, wood-plastic plywood was fabricated with high density polyethylene (HDPE) film and poplar veneer by hot-pressing. To improve the interfacial adhesion between the wood veneer and HDPE film, silane A-171 (vinyltrimethoxysilane) was used to treat the surface of poplar veneer by spraying. The effects of silane agent on the veneer surface properties as well as the physical-mechanical performance of wood-plastic plywood were evaluated. The adsorption of several prehydrolyzed alkoxysilanes onto the veneer surface and the existence of a covalent bonding between the wood veneer and silane agent were confirmed using FTIR, XPS and contact angle. Silane surface treatment resulted in enhancement of shear strength and water resistance. When one layer HDPE film was used as adhesive, it caused 293.2% increase in shear strength, 34.6% and 40.8% reduction in water absorption and thickness swelling, respectively. In addition, the wood failure also increased from 5% to 100% due to the silane modification. Dynamic mechanical analysis (DMA) results showed that treated plywood have higher storage modulus, lower tan δ peak value and lagged temperature for tan δ peak value with respect to untreated plywood. Experimental results of interfacial morphology by SEM further revealed better interaction between silane A-171 treated veneer and HDPE film.

  19. Bacterial adhesion to protein-coated surfaces: An AFM and QCM-D study

    Science.gov (United States)

    Strauss, Joshua; Liu, Yatao; Camesano, Terri A.

    2009-09-01

    Bacterial adhesion to biomaterials, mineral surfaces, or other industrial surfaces is strongly controlled by the way bacteria interact with protein layers or organic matter and other biomolecules that coat the materials. Despite this knowledge, many studies of bacterial adhesion are performed under clean conditions, instead of in the presence of proteins or organic molecules. We chose fetal bovine serum (FBS) as a model protein, and prepared FBS films on quartz crystals. The thickness of the FBS layer was characterized using atomic force microscopy (AFM) imaging under liquid and quartz crystal microbalance with dissipation (QCM-D). Next, we characterized how the model biomaterial surface would interact with the nocosomial pathogen Staphylococcus epidermidis. An AFM probe was coated with S. epidermidis cells and used to probe a gold slide that had been coated with FBS or another protein, fibronectin (FN). These experiments show that AFM and QCM-D can be used in complementary ways to study the complex interactions between bacteria, proteins, and surfaces.

  20. Surface Energy and Setting Process of Contacting Surfaces

    Directory of Open Access Journals (Sweden)

    M. V. Musokhranov

    2014-01-01

    Full Text Available The paper deals with a challenge in terms of ensuring an accuracy of the relative position of the conjugated surfaces that is to determine a coefficient of friction. To solve it, there is a proposal to use the surface energy, as a tool that influences the contacting parts nature. Presently, energy of the surface layers at best is only stated, but not used in practice.Analysis of the conditions of interaction between two contacting surfaces, such as seizing and setting cannot be explained only from the position of the roughness parameters. It is found that these phenomena are explained by the appearing gripe (setting bridges, which result from the energy of interaction between two or more adjacent surfaces. The emerging phenomenon such as micro welding, i.e. occurring bonds, is caused by the overflow of energy, according to the theory of physics, from the surface with a high level of energy to the surface with the smaller one to balance the system as a whole.The paper shows that through the use of process, controlling the depth of the surface layer and creating a certain structure, the energy level of the material as a whole can be specified. And this will allow us to provide the necessary performance and mechanical properties. It means to create as many gripe bridges as possible to ensure continuous positioning i.e. a fixed connection of the contacting surfaces.It was determined that to increase a value of the friction coefficient, the physical and mechanical properties of the surface layer of the parts material must be taken into account, namely, in the part body accumulate the energy to be consumed for forming the surface.The paper gives recommendations for including the parts of the surface energy in the qualitative indicators of characteristics. This will make a technologist, when routing a process, to choose such operations and modes to provide the designer-specified parameters not only of the accuracy and surface finish, but also of the

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

    Science.gov (United States)

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

    2016-07-01

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

  2. Surface energy and surface tension of liquid metal nanodrops

    Directory of Open Access Journals (Sweden)

    Shebzukhov A.A.

    2011-05-01

    Full Text Available A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  3. Surface energy and surface tension of liquid metal nanodrops

    Science.gov (United States)

    Shebzukhova, M. A.; Shebzukhov, A. A.

    2011-05-01

    A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  4. Surface energy and surface tension of liquid metal nanodrops

    OpenAIRE

    Shebzukhov A.A.; Shebzukhova M.A.

    2011-01-01

    A unitary approach has been proposed for the calculation of surface energy and surface tension of nanoparticle being in equilibrium with its saturated vapor on both flat and curved surfaces at given temperature. The final equations involve parameters dependent on the type of premelting structure: bcc, fcc or hcp.

  5. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  6. The influence of surface DBD plasma treatment on the adhesion of coatings to high-tech textiles

    NARCIS (Netherlands)

    Šimor, M.; Creyghton, Y.; Wypkema, A.W.; Zemek, J.

    2010-01-01

    The surface of high-performance poly(ethylene terephthalate) (PET) fibers is difficult to wet and impossible to chemically bond to different matrices. Sizing applied on the fiber surface usually improves fiber wetting, but prevents good adhesion between a matrix and the fiber surface. The present

  7. Heparanase facilitates cell adhesion and spreading by clustering of cell surface heparan sulfate proteoglycans.

    Directory of Open Access Journals (Sweden)

    Flonia Levy-Adam

    2008-06-01

    Full Text Available Heparanase is a heparan sulfate (HS degrading endoglycosidase participating in extracellular matrix degradation and remodeling. Apart of its well characterized enzymatic activity, heparanase was noted to exert also enzymatic-independent functions. Non-enzymatic activities of heparanase include enhanced adhesion of tumor-derived cells and primary T-cells. Attempting to identify functional domains of heparanase that would serve as targets for drug development, we have identified heparin binding domains of heparanase. A corresponding peptide (residues Lys(158-Asp(171, termed KKDC was demonstrated to physically associate with heparin and HS, and to inhibit heparanase enzymatic activity. We hypothesized that the pro-adhesive properties of heparanase are mediated by its interaction with cell surface HS proteoglycans, and utilized the KKDC peptide to examine this possibility. We provide evidence that the KKDC peptide interacts with cell membrane HS, resulting in clustering of syndecan-1 and syndecan-4. We applied classical analysis of cell morphology, fluorescent and time-lapse microscopy and demonstrated that the KKDC peptide efficiently stimulates the adhesion and spreading of various cell types, mediated by PKC, Src, and the small GTPase Rac1. These results support, and further substantiate the notion that heparanase function is not limited to its enzymatic activity.

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

    Science.gov (United States)

    Wang, Michael; Sakamoto, Jeff

    2018-02-01

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

  9. Influence of residual stress on the adhesion and surface morphology of PECVD-coated polypropylene

    Science.gov (United States)

    Jaritz, Montgomery; Hopmann, Christian; Behm, Henrik; Kirchheim, Dennis; Wilski, Stefan; Grochla, Dario; Banko, Lars; Ludwig, Alfred; Böke, Marc; Winter, Jörg; Bahre, Hendrik; Dahlmann, Rainer

    2017-11-01

    The properties of plasma-enhanced chemical vapour deposition (PECVD) coatings on polymer materials depend to some extent on the surface and material properties of the substrate. Here, isotactic polypropylene (PP) substrates are coated with silicon oxide (SiO x ) films. Plasmas for the deposition of SiO x are energetic and oxidative due to the high amount of oxygen in the gas mixture. Residual stress measurements using single Si cantilever stress sensors showed that these coatings contain high compressive stress. To investigate the influence of the plasma and the coatings, residual stress, silicon organic (SiOCH) coatings with different thicknesses between the PP and the SiO x coating are used as a means to protect the substrate from the oxidative SiO x coating process. Pull-off tests are performed to analyse differences in the adhesion of these coating systems. It could be shown that the adhesion of the PECVD coatings on PP depends on the coatings’ residual stress. In a PP/SiOCH/SiO x -multilayer system the residual stress can be significantly reduced by increasing the thickness of the SiOCH coating, resulting in enhanced adhesion.

  10. Surface free energy of ultra-high molecular weight polyethylene modified by electron and gamma irradiation

    International Nuclear Information System (INIS)

    Abdul-Kader, A.M.; Turos, A.; Radwan, R.M.; Kelany, A.M.

    2009-01-01

    Surface free energy of biocompatible polymers is important factor which affects the surface properties such as wetting, adhesion and biocompatibility. In the present work, the change in the surface free energy of ultra-high molecular weight polyethylene (UHMWPE) samples, which is produced by electron beam and gamma ray irradiation were, investigated. Mechanism of the changes in surface free energy induced by irradiations of doses ranging from 25 to 500 kGy was studied. FTIR technique was applied for sample analysis. Contact angle measurements showed that wettability and surface free energy of samples have increased with increasing the irradiation dose, where the values of droplet contact angle of the samples decrease gradually with increasing the radiation dose. The increase in the wettability and surface free energy of the irradiated samples are attributed to formation of hydrophilic groups on the polymer surface by the oxidation, which apparently occurs by exposure of irradiated samples to the air.

  11. Wetting, adhesion and friction of superhydrophobic and hydrophilic leaves and fabricated micro/nanopatterned surfaces

    Science.gov (United States)

    Bhushan, Bharat; Jung, Yong Chae

    2008-06-01

    Superhydrophobic surfaces have considerable technological potential for various applications due to their extreme water-repellent properties. When two hydrophilic bodies are brought into contact, any liquid present at the interface forms menisci, which increases adhesion/friction and the magnitude is dependent upon the contact angle. Certain plant leaves are known to be superhydrophobic in nature due to their roughness and the presence of a thin wax film on the leaf surface. Various leaf surfaces on the microscale and nanoscale have been characterized in order to separate out the effects of the microbumps and nanobumps and the wax on the hydrophobicity. The next logical step in realizing superhydrophobic surfaces that can be produced is to design surfaces based on understanding of the leaves. The effect of micropatterning and nanopatterning on the hydrophobicity was investigated for two different polymers with micropatterns and nanopatterns. Scale dependence on adhesion was also studied using atomic force microscope tips of various radii. Studies on silicon surfaces patterned with pillars of varying diameter, height and pitch values and deposited with a hydrophobic coating were performed to demonstrate how the contact angles vary with the pitch. The effect of droplet size on contact angle was studied by droplet evaporation and a transition criterion was developed to predict when air pockets cease to exist. Finally, an environmental scanning electron microscope study on the effect of droplet size of about 20 µm radius on the contact angle of patterned surfaces is presented. The importance of hierarchical roughness structure on destabilization of air pockets is discussed.

  12. An investigation of the effect of scaling-induced surface roughness on bacterial adhesion in common fixed dental restorative materials.

    Science.gov (United States)

    Checketts, Matthew R; Turkyilmaz, Ilser; Asar, Neset Volkan

    2014-11-01

    Bacterial plaque must be routinely removed from teeth, adjacent structures, and prostheses. However, the removal of this plaque can inadvertently increase the risk of future bacterial adhesion. The purpose of this investigation was to assess the change in the surface roughness of 3 different surfaces after dental prophylactic instrumentation and how this influenced bacterial adhesion. Forty specimens each of Type III gold alloy, lithium disilicate, and zirconia were fabricated in the same dimensions. The specimens were divided into 4 groups: ultrasonic scaler, stainless steel curette, prophylaxis cup, and control. Pretreatment surface roughness measurements were made with a profilometer. Surface treatments in each group were performed with a custom mechanical scaler. Posttreatment surface roughness values were measured. In turn, the specimens were inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces viscosus. Bacterial adhesion was assessed by rinsing the specimens with sterile saline to remove unattached cells. The specimens were then placed in sterile tubes with 1 mL of sterile saline. The solution was plated and quantified. Scanning electron microscopy was performed. The statistical analysis of surface roughness was completed by using repeated-measures single-factor ANOVA with a Bonferroni correction. The surface roughness values for gold alloy specimens increased as a result of prophylaxis cup treatment (0.221 to 0.346 Ra) (Pbacterial adhesion to gold alloy proved inconclusive. A quantitative comparison indicated no statistically significant differences in pretreatment and posttreatment surface roughness values for lithium disilicate and zirconia specimens. In spite of these similarities, the overall bacterial adherence values for lithium disilicate were significantly greater than those recorded for gold alloy or zirconia (PInstrumentation of the lithium disilicate and zirconia with the stainless steel curette significantly increased

  13. Surface Proteins of Lactococcus lactis: Bacterial Resources for Muco-adhesion in the Gastrointestinal Tract

    Directory of Open Access Journals (Sweden)

    Muriel Mercier-Bonin

    2017-11-01

    Full Text Available Food and probiotic bacteria, in particular lactic acid bacteria, are ingested in large amounts by humans and are part of the transient microbiota which is increasingly considered to be able to impact the resident microbiota and thus possibly the host health. The lactic acid bacterium Lactococcus lactis is extensively used in starter cultures to produce dairy fermented food. Also because of a generally recognized as safe status, L. lactis has been considered as a possible vehicle to deliver in vivo therapeutic molecules with anti-inflammatory properties in the gastrointestinal tract. One of the key factors that may favor health effects of beneficial bacteria to the host is their capacity to colonize transiently the gut, notably through close interactions with mucus, which covers and protects the intestinal epithelium. Several L. lactis strains have been shown to exhibit mucus-binding properties and bacterial surface proteins have been identified as key determinants of such capacity. In this review, we describe the different types of surface proteins found in L. lactis, with a special focus on mucus-binding proteins and pili. We also review the different approaches used to investigate the adhesion of L. lactis to mucus, and particularly to mucins, one of its major components, and we present how these approaches allowed revealing the role of surface proteins in muco-adhesion.

  14. Coating polypropylene surfaces with protease weakens the adhesion and increases the dispersion of Candida albicans cells.

    Science.gov (United States)

    Andreani, Eugenio Spadoni; Villa, Federica; Cappitelli, Francesca; Krasowska, Anna; Biniarz, Piotr; Łukaszewicz, Marcin; Secundo, Francesco

    2017-03-01

    To investigate the ability of the proteases, subtilisin and α-chymotrypsin (aCT), to inhibit the adhesion of Candida albicans biofilm to a polypropylene surface. The proteases were immobilized on plasma-treated polypropylene by covalently linking them with either glutaraldehyde (GA) or N'-diisopropylcarbodiimide (DIC) and N-hydroxysuccinimide (NHS). The immobilization did not negatively affect the enzyme activity and in the case of subtilisin, the activity was up to 640% higher than that of the free enzyme when using N-acetyl phenylalanine ethyl ester as the substrate. The efficacies against biofilm dispersal for the GA-linked SubC and aCT coatings were 41 and 55% higher than the control (polypropylene coated with only GA), respectively, whereas no effect was observed with enzymes immobilized with DIC and NHS. The higher dispersion efficacy observed for the proteases immobilized with GA could be both steric (proper orientation of the active site) and dynamic (higher protein mobility/flexibility). Proteases immobilized on a polypropylene surface reduced the adhesion of C. albicans biofilms and therefore may be useful in developing anti-biofilm surfaces based on non-toxic molecules and sustainable strategies.

  15. Adhesion of neural cells on silicon wafer with nano-topographic surface

    Science.gov (United States)

    Fan, Y. W.; Cui, F. Z.; Chen, L. N.; Zhai, Y.; Xu, Q. Y.; Lee, I.-S.

    2002-02-01

    The adherence and subsequent viability of central neural cells (substantia nigra) on silicon wafers with different surface roughness conditions were investigated. Various roughness conditions of the silicon wafer were achieved by etching at different times. The topography was evaluated by AFM. Primary neurons were obtained from Wistar rats. The adherence and subsequent viability of the cells on the wafer were examined by scanning electronic microscopy and fluorescence immunostaining of tyrosine hydroxylase. It is found that the surface roughness affects significantly cell adhesion and viability. Cells can survive for over 5 days on the surface with average roughness in the range 20-70 nm. Such a treatment may provide a new method to make a mild interface of silicon-based electronic devices and neurons as well as other living tissues.

  16. Surface physicochemical properties at the micro and nano length scales: role on bacterial adhesion and Xylella fastidiosa biofilm development.

    Science.gov (United States)

    Lorite, Gabriela S; Janissen, Richard; Clerici, João H; Rodrigues, Carolina M; Tomaz, Juarez P; Mizaikoff, Boris; Kranz, Christine; de Souza, Alessandra A; Cotta, Mônica A

    2013-01-01

    The phytopathogen Xylella fastidiosa grows as a biofilm causing vascular occlusion and consequently nutrient and water stress in different plant hosts by adhesion on xylem vessel surfaces composed of cellulose, hemicellulose, pectin and proteins. Understanding the factors which influence bacterial adhesion and biofilm development is a key issue in identifying mechanisms for preventing biofilm formation in infected plants. In this study, we show that X. fastidiosa biofilm development and architecture correlate well with physicochemical surface properties after interaction with the culture medium. Different biotic and abiotic substrates such as silicon (Si) and derivatized cellulose films were studied. Both biofilms and substrates were characterized at the micro- and nanoscale, which corresponds to the actual bacterial cell and membrane/ protein length scales, respectively. Our experimental results clearly indicate that the presence of surfaces with different chemical composition affect X. fastidiosa behavior from the point of view of gene expression and adhesion functionality. Bacterial adhesion is facilitated on more hydrophilic surfaces with higher surface potentials; XadA1 adhesin reveals different strengths of interaction on these surfaces. Nonetheless, despite different architectural biofilm geometries and rates of development, the colonization process occurs on all investigated surfaces. Our results univocally support the hypothesis that different adhesion mechanisms are active along the biofilm life cycle representing an adaptation mechanism for variations on the specific xylem vessel composition, which the bacterium encounters within the infected plant.

  17. Adhesion and Cohesion

    Directory of Open Access Journals (Sweden)

    J. Anthony von Fraunhofer

    2012-01-01

    Full Text Available The phenomena of adhesion and cohesion are reviewed and discussed with particular reference to dentistry. This review considers the forces involved in cohesion and adhesion together with the mechanisms of adhesion and the underlying molecular processes involved in bonding of dissimilar materials. The forces involved in surface tension, surface wetting, chemical adhesion, dispersive adhesion, diffusive adhesion, and mechanical adhesion are reviewed in detail and examples relevant to adhesive dentistry and bonding are given. Substrate surface chemistry and its influence on adhesion, together with the properties of adhesive materials, are evaluated. The underlying mechanisms involved in adhesion failure are covered. The relevance of the adhesion zone and its importance with regard to adhesive dentistry and bonding to enamel and dentin is discussed.

  18. Expression of cell adhesion and differentiation related genes in MC3T3 osteoblasts plated on titanium alloys: role of surface properties

    International Nuclear Information System (INIS)

    Sista, Subhash; Wen, Cuie; Hodgson, Peter D.; Pande, Gopal

    2013-01-01

    It is important to understand the cellular and molecular events that take place at the cell–material interface of implants used for bone repair. An understanding of the mechanisms involved in the initial stages of osteoblast interactions with the surface of the implant material is fundamental in deciding the fate of the cells that come in contact with it. In this study, we compared the relative gene expression of markers that are known to be associated with cell adhesion and differentiation in MC3T3 osteoblast cells, at various time points after plating the cells on surfaces of titanium (Ti) and its two alloys, titanium–zirconium (TiZr) and titanium–niobium (TiNb) by using Quantitative Real Time Polymerase Chain Reaction (RT-PCR). Our analysis indicated that expression of adhesion supporting genes was higher on TiZr surface as compared to Ti and TiNb. The behavior of these genes is possibly driven by a higher surface energy of TiZr. However no significant difference in the expression of differentiation related genes could be seen between the two alloys, although on both substrates it was higher as compared to unalloyed Ti. We propose that substrate composition of the alloys can influence the adhesion and differentiation related gene expression and that Ti alloys are better substrates for inducing osteogenesis as compared to unalloyed Ti. - Highlights: ► Methodology for comparing gene expression in osteoblasts plated on Ti, TiZr or TiNb ► Alloys with higher surface energy (TiZr) induce cell adhesion genes more efficiently ► Alloyed Ti is superior to unalloyed Ti to induce osteoblast differentiation genes

  19. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    International Nuclear Information System (INIS)

    Brajkovic, Denis; Antonijevic, Djordje; Milovanovic, Petar; Kisic, Danilo; Zelic, Ksenija; Djuric, Marija; Rakocevic, Zlatko

    2014-01-01

    Graphical abstract: - Highlights: • Surface free energy and surface roughness influence bacterial adhesion. • Bacterial colonization causes periimplantitis and implant loss. • Zinc-based, glass-ionomers and resin-cements were investigated. • Glass-ionomers-cements present the lowest values of surface free energy and roughness. • Glass-ionomer-cements surface properties result with reduced bacterial adhesion. - Abstract: Background: Material surface free energy and surface roughness strongly influence the bacterial adhesion in oral cavity. The aim of this study was to analyze these two parameters in various commercial luting agents used for cementation of implant restorations. Materials and methods: Zinc-based, glass-ionomers, resin modified glass-ionomer and resin-cements were investigated. Contact angle and surface free energy were measured by contact angle analyzer using Image J software program. Materials’ average roughness and fractal dimension were calculated based on Atomic Force Microscope topography images. Results: Zinc phosphate cements presented significantly higher total surface free energy and significantly lower dispersive component of surface free energy compared to other groups, while resin-cements showed significantly lower polar component than other groups. The surface roughness and fractal dimension values were statistically the highest in the zinc phosphate cements and the lowest for the glass-ionomers cements. Conclusion: Glass-ionomers-cements presented lower values of surface free energy and surface roughness than zinc phosphate and resin cements, indicating that their surfaces are less prone to biofilm adhesion. Practical implications: Within limitations of an in vitro trial, our results indicate that glass-ionomers-cements could be the cements of choice for fixation of cement retained implant restorations due to superior surface properties compared to zinc phosphate and resin cements, which may result in reduced plaque formation

  20. Surface characterization of the cement for retention of implant supported dental prostheses: In vitro evaluation of cement roughness and surface free energy

    Energy Technology Data Exchange (ETDEWEB)

    Brajkovic, Denis [Clinic for Dentistry, Department of Maxillofacial Surgery, Faculty of Medical Sciences, University of Kragujevac, Svetozara Markovica 69, 34000 Kragujevac (Serbia); Antonijevic, Djordje; Milovanovic, Petar [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Kisic, Danilo [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia); Zelic, Ksenija; Djuric, Marija [Laboratory for Anthropology, Institute of Anatomy, School of Medicine, University of Belgrade, Dr. Subotica 4/2, 11000 Belgrade (Serbia); Rakocevic, Zlatko, E-mail: zlatkora@vinca.rs [Laboratory for Atomic Physics, Institute of Nuclear Sciences “Vinca”, University of Belgrade, Belgrade (Serbia)

    2014-08-30

    Graphical abstract: - Highlights: • Surface free energy and surface roughness influence bacterial adhesion. • Bacterial colonization causes periimplantitis and implant loss. • Zinc-based, glass-ionomers and resin-cements were investigated. • Glass-ionomers-cements present the lowest values of surface free energy and roughness. • Glass-ionomer-cements surface properties result with reduced bacterial adhesion. - Abstract: Background: Material surface free energy and surface roughness strongly influence the bacterial adhesion in oral cavity. The aim of this study was to analyze these two parameters in various commercial luting agents used for cementation of implant restorations. Materials and methods: Zinc-based, glass-ionomers, resin modified glass-ionomer and resin-cements were investigated. Contact angle and surface free energy were measured by contact angle analyzer using Image J software program. Materials’ average roughness and fractal dimension were calculated based on Atomic Force Microscope topography images. Results: Zinc phosphate cements presented significantly higher total surface free energy and significantly lower dispersive component of surface free energy compared to other groups, while resin-cements showed significantly lower polar component than other groups. The surface roughness and fractal dimension values were statistically the highest in the zinc phosphate cements and the lowest for the glass-ionomers cements. Conclusion: Glass-ionomers-cements presented lower values of surface free energy and surface roughness than zinc phosphate and resin cements, indicating that their surfaces are less prone to biofilm adhesion. Practical implications: Within limitations of an in vitro trial, our results indicate that glass-ionomers-cements could be the cements of choice for fixation of cement retained implant restorations due to superior surface properties compared to zinc phosphate and resin cements, which may result in reduced plaque formation

  1. Adhesion of nano-sized particles to the surface of bacteria: mechanistic study with the extended DLVO theory.

    Science.gov (United States)

    Hwang, Geelsu; Ahn, Ik-Sung; Mhin, Byung Jin; Kim, Ju-Young

    2012-09-01

    Due to the increasing production and application of nanoparticles, their release into the environment would be inevitable, which requires a better understanding of their fate in the environment. When considering their toxic behavior or biodegradation as their fate, their adhesion to the cell surface must be the first step to be thoroughly studied. In this study, nano-sized polymeric particles of urethane acrylate with various hydrophobicity and ionic properties were synthesized as model nanoparticles, and their adhesion to Pseudomonas putida strains was monitored. The higher hydrophobicity and positive charge density on the particle surface exhibited the larger adhesion to the bacteria, whereas negative charge density on the particle hindered their adhesion to the bacteria, albeit high hydrophobicity of particle. These observations were successfully explained with the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Copyright © 2012 Elsevier B.V. All rights reserved.

  2. Supersonic Retropulsion Surface Preparation of Carbon Fiber Reinforced Epoxy Composites for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Belcher, Marcus A.; Wohl, Christopher J.; Blohowiak, Kay Y.; Connell, John W.

    2013-01-01

    Surface preparation is widely recognized as a key step to producing robust and predictable bonds in a precise and reproducible manner. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, can lack precision and reproducibility, which can lead to variation in surface properties and subsequent bonding performance. The use of a laser to ablate composite surface resin can provide an efficient, precise, and reproducible means of preparing composite surfaces for adhesive bonding. Advantages include elimination of physical waste (i.e., grit media and sacrificial peel ply layers that ultimately require disposal), reduction in process variability due to increased precision (e.g. increased reproducibility), and automation of surface preparation, all of which improve reliability and process control. This paper describes a Nd:YAG laser surface preparation technique for composite substrates and the mechanical performance and failure modes of bonded laminates thus prepared. Additionally, bonded specimens were aged in a hot, wet environment for approximately one year and subsequently mechanically tested. The results of a one year hygrothermal aging study will be presented.

  3. Fibrin clot adhesion to root surface treated with tetracycline hydrochloride and ethylenediaminetetraacetic acid: A scanning electron microscopic study

    Directory of Open Access Journals (Sweden)

    Chandran Preeja

    2013-01-01

    Full Text Available Background: Connective tissue attachment following periodontal regenerative surgery is directly related to the attachment of fibrin clot on to the root surface during early wound healing events.The adhesion of fibrin clot to the root surface affected by periodontal disease depends on the biologic acceptance of the root surface which can be accomplished by various root conditioning procedures during periodontal therapy. The present in vitro study has been designed to evaluate and compare the degree of fibrin clot adhesion to root surfaces treated with root conditioning agents tetracycline hydrochloride and ethylenediaminetetraacetic acid (EDTA. Materials and Methods: A total of 30 dentin blocks are divided into three groups and treated with tetracycline hydrochloride, EDTA and phosphate buffered saline and a drop of blood is added to each dentin block. The dentin blocks are then prepared for scanning electron microscopic analysis and examined for the degree of fibrin network frmation and entrapped erythrocytes. Results: The degree of fibrin clot adhesion was highest with tetracycline hydrochloride group, then with control group and least with EDTA treated group. Conclusion: According to the results of the present study, root conditioning with tetracycline hydrochloride produces a biologically acceptable root surface with enhanced fibrin clot adhesion, which is a critical step in early wound healing process. EDTA gel appears less effective in producing a root surface necessary for the adhesion of fibrin clot. The control without any root conditioning procedure showed poor fibrin clot adhesion when compared to tetracycline treated group, but when compared to EDTA treated group the fibrin clot adhesion was slightly better.

  4. Adjustment of surface chemical and physical properties with functionalized polymers to control cell adhesion

    Science.gov (United States)

    Zhou, Zhaoli

    Cell-surface interaction is crucial in many cellular functions such as movement, growth, differentiation, proliferation and survival. In the present work, we have developed several strategies to design and prepare synthetic polymeric materials with selected cues to control cell attachment. To promote neuronal cell adhesion on the surfaces, biocompatible, non-adhesive PEG-based materials were modified with neurotransmitter acetylcholine functionalities to produce hydrogels with a range of porous structures, swollen states, and mechanical strengths. Mice hippocampal cells cultured on the hydrogels showed differences in number, length of processes and exhibited different survival rates, thereby highlighting the importance of chemical composition and structure in biomaterials. Similar strategies were used to prepare polymer brushes to assess how topographical cues influence neuronal cell behaviors. The brushes were prepared using the "grown from" method through surface-initiated atom transfer radical polymerization (SI-ATRP) reactions and further patterned via UV photolithography. Protein absorption tests and hippocampal neuronal cell culture of the brush patterns showed that both protein and neuronal cells can adhere to the patterns and therefore can be guided by the patterns at certain length scales. We also prepared functional polymers to discourage attachment of undesirable cells on the surfaces. For example, we synthesized PEG-perfluorinated alkyl amphiphilic surfactants to modify polystyrene-block-poly(ethylene-ran-butylene)- block-polyisoprene (SEBI or K3) triblock copolymers for marine antifouling/fouling release surface coatings. Initial results showed that the polymer coated surfaces can facilitate removal of Ulva sporelings on the surfaces. In addition, we prepared both bioactive and dual functional biopassive/bioactive antimicrobial coatings based on SEBI polymers. Incubating the polymer coated surfaces with gram-positive bacteria (S. aureus), gram

  5. Proteomic Profiling of Neuroblastoma Cells Adhesion on Hyaluronic Acid-Based Surface for Neural Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Ming-Hui Yang

    2016-01-01

    Full Text Available The microenvironment of neuron cells plays a crucial role in regulating neural development and regeneration. Hyaluronic acid (HA biomaterial has been applied in a wide range of medical and biological fields and plays important roles in neural regeneration. PC12 cells have been reported to be capable of endogenous NGF synthesis and secretion. The purpose of this research was to assess the effect of HA biomaterial combining with PC12 cells conditioned media (PC12 CM in neural regeneration. Using SH-SY5Y cells as an experimental model, we found that supporting with PC12 CM enhanced HA function in SH-SY5Y cell proliferation and adhesion. Through RP-nano-UPLC-ESI-MS/MS analyses, we identified increased expression of HSP60 and RanBP2 in SH-SY5Y cells grown on HA-modified surface with cotreatment of PC12 CM. Moreover, we also identified factors that were secreted from PC12 cells and may promote SH-SY5Y cell proliferation and adhesion. Here, we proposed a biomaterial surface enriched with neurotrophic factors for nerve regeneration application.

  6. Nanosecond laser ablated copper superhydrophobic surface with tunable ultrahigh adhesion and its renewability with low temperature annealing

    Science.gov (United States)

    He, An; Liu, Wenwen; Xue, Wei; Yang, Huan; Cao, Yu

    2018-03-01

    Recently, metallic superhydrophobic surfaces with ultrahigh adhesion have got plentiful attention on account of their significance in scientific researches and industrial applications like droplet transport, drug delivery and novel microfluidic devices. However, the long lead time and transience hindered its in-depth development and industrial application. In this work, nanosecond laser ablation was carried out to construct grid of micro-grooves on copper surface, whereafter, by applying fast ethanol assisted low-temperature annealing, we obtained surface with superhydrophobicity and ultrahigh adhesion within hours. And the ultrahigh adhesion force was found tunable by varying the groove spacing. Using ultrasonic cleaning as the simulation of natural wear and tear in service, the renewability of superhydrophobicity was also investigated, and the result shows that the contact angle can rehabilitate promptly by the processing of ethanol assisted low-temperature annealing, which gives a promising fast and cheap circuitous strategy to realize the long wish durable metallic superhydrophobic surfaces in practical applications.

  7. Laser Ablation Surface Preparation of Ti-6A1-4V for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Watson, Kent A.; Morales, Guillermo; Williams, Thomas; Hicks, Robert; Wohl, Christopher J.; Hopkins, John W.; Connell, John W.

    2012-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires certification before it can be incorporated in primary structures for commercial aviation without disbond-arrestment features or redundant load paths. Surface preparation is widely recognized as the key step to producing robust and predictable bonds. Laser ablation imparts both topographical and chemical changes to a surface which can lead to increased bond durability. A laser based process provides an alternative to chemical-dip, manual abrasion and grit blast treatments which are expensive, hazardous, polluting, and less precise. This report documents preliminary testing of a surface preparation technique using laser ablation as a replacement for the chemical etch and abrasive processes currently applied to Ti-6Al-4V alloy adherends. Failure mode, surface roughness, and chemical makeup were analyzed using fluorescence enhanced visualization, microscopy, and X-ray photoelectron spectroscopy, respectively. Single lap shear tests were conducted on bonded and aged specimens to observe bond strength retention and failure mode. Some promising results showed increasing strength and durability of lap shear specimens as laser ablation coverage area and beam intensity increased. Chemical analyses showed trends for surface chemical species which correlated with improved bond strength and durability. Combined, these results suggest that laser ablation is a viable process for inclusion with or/and replacement of one or more currently used titanium surface treatments. On-going work will focus on additional mechanical tests to further demonstrate improved bond durability.

  8. The macrophage CD163 surface glycoprotein is an erythroblast adhesion receptor

    DEFF Research Database (Denmark)

    Fabriek, Babs O; Polfliet, Machteld M J; Vloet, Rianka P M

    2007-01-01

    on the surface of macrophages in erythroblastic islands, in erythroblast binding. In particular, the monoclonal antibody ED2 was found to inhibit erythroblast binding to bone marrow macrophages. Here, we identify the ED2 antigen as the rat CD163 surface glycoprotein, a member of the group B scavenger receptor...... cysteine-rich (SRCR) family that has previously been shown to function as a receptor for hemoglobin-haptoglobin (Hb-Hp) complexes and is believed to contribute to the clearance of free hemoglobin. CD163 transfectants and recombinant protein containing the extracellular domain of CD163 supported...... the adhesion of erythroblastic cells. Furthermore, we identified a 13-amino acid motif (CD163p2) corresponding to a putative interaction site within the second scavenger receptor domain of CD163 that could mediate erythroblast binding. Finally, CD163p2 promoted erythroid expansion in vitro, suggesting...

  9. Solar energy converter using surface plasma waves

    Science.gov (United States)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  10. Chitosan Mediates Germling Adhesion in Magnaporthe oryzae and Is Required for Surface Sensing and Germling Morphogenesis.

    Directory of Open Access Journals (Sweden)

    Ivey A Geoghegan

    2016-06-01

    Full Text Available The fungal cell wall not only plays a critical role in maintaining cellular integrity, but also forms the interface between fungi and their environment. The composition of the cell wall can therefore influence the interactions of fungi with their physical and biological environments. Chitin, one of the main polysaccharide components of the wall, can be chemically modified by deacetylation. This reaction is catalyzed by a family of enzymes known as chitin deacetylases (CDAs, and results in the formation of chitosan, a polymer of β1,4-glucosamine. Chitosan has previously been shown to accumulate in the cell wall of infection structures in phytopathogenic fungi. Here, it has long been hypothesized to act as a 'stealth' molecule, necessary for full pathogenesis. In this study, we used the crop pathogen and model organism Magnaporthe oryzae to test this hypothesis. We first confirmed that chitosan localizes to the germ tube and appressorium, then deleted CDA genes on the basis of their elevated transcript levels during appressorium differentiation. Germlings of the deletion strains showed loss of chitin deacetylation, and were compromised in their ability to adhere and form appressoria on artificial hydrophobic surfaces. Surprisingly, the addition of exogenous chitosan fully restored germling adhesion and appressorium development. Despite the lack of appressorium development on artificial surfaces, pathogenicity was unaffected in the mutant strains. Further analyses demonstrated that cuticular waxes are sufficient to over-ride the requirement for chitosan during appressorium development on the plant surface. Thus, chitosan does not have a role as a 'stealth' molecule, but instead mediates the adhesion of germlings to surfaces, thereby allowing the perception of the physical stimuli necessary to promote appressorium development. This study thus reveals a novel role for chitosan in phytopathogenic fungi, and gives further insight into the mechanisms

  11. Chitosan Mediates Germling Adhesion in Magnaporthe oryzae and Is Required for Surface Sensing and Germling Morphogenesis

    Science.gov (United States)

    Geoghegan, Ivey A.; Gurr, Sarah J.

    2016-01-01

    The fungal cell wall not only plays a critical role in maintaining cellular integrity, but also forms the interface between fungi and their environment. The composition of the cell wall can therefore influence the interactions of fungi with their physical and biological environments. Chitin, one of the main polysaccharide components of the wall, can be chemically modified by deacetylation. This reaction is catalyzed by a family of enzymes known as chitin deacetylases (CDAs), and results in the formation of chitosan, a polymer of β1,4-glucosamine. Chitosan has previously been shown to accumulate in the cell wall of infection structures in phytopathogenic fungi. Here, it has long been hypothesized to act as a 'stealth' molecule, necessary for full pathogenesis. In this study, we used the crop pathogen and model organism Magnaporthe oryzae to test this hypothesis. We first confirmed that chitosan localizes to the germ tube and appressorium, then deleted CDA genes on the basis of their elevated transcript levels during appressorium differentiation. Germlings of the deletion strains showed loss of chitin deacetylation, and were compromised in their ability to adhere and form appressoria on artificial hydrophobic surfaces. Surprisingly, the addition of exogenous chitosan fully restored germling adhesion and appressorium development. Despite the lack of appressorium development on artificial surfaces, pathogenicity was unaffected in the mutant strains. Further analyses demonstrated that cuticular waxes are sufficient to over-ride the requirement for chitosan during appressorium development on the plant surface. Thus, chitosan does not have a role as a 'stealth' molecule, but instead mediates the adhesion of germlings to surfaces, thereby allowing the perception of the physical stimuli necessary to promote appressorium development. This study thus reveals a novel role for chitosan in phytopathogenic fungi, and gives further insight into the mechanisms governing

  12. The influence of surface DBD plasma treatment on the adhesion of coatings to high-tech textiles

    Czech Academy of Sciences Publication Activity Database

    Šimor, M.; Creyghton, Y.; Wypton, A.; Zemek, Josef

    2010-01-01

    Roč. 24, č. 1 (2010), s. 77-97 ISSN 0169-4243 Institutional research plan: CEZ:AV0Z10100521 Keywords : adhesion * plasma treatment * surface DBD * composite * surface modification * XPS * PET Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.980, year: 2010

  13. Platelet adhesion and plasma protein adsorption control of collagen surfaces by He+ ion implantation

    International Nuclear Information System (INIS)

    Kurotobi, K.; Suzuki, Y.; Nakajima, H.; Suzuki, H.; Iwaki, M.

    2003-01-01

    He + ion implanted collagen-coated tubes with a fluence of 1 x 10 14 ions/cm 2 were exhibited antithrombogenicity. To investigate the mechanisms of antithrombogenicity of these samples, plasma protein adsorption assay and platelet adhesion experiments were performed. The adsorption of fibrinogen (Fg) and von Willebrand factor (vWf) was minimum on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 . Platelet adhesion (using platelet rich plasma) was inhibited on the He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was accelerated on the untreated collagen and ion implanted collagen with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Platelet activation with washed platelets was observed on untreated collagen and He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and was inhibited with fluences of 1 x 10 13 , 1 x 10 15 and 1 x 10 16 ions/cm 2 . Generally, platelets can react with a specific ligand inside the collagen (GFOGER sequence). The results of platelets adhesion experiments using washed platelets indicated that there were no ligands such as GFOGER on the He + ion implanted collagen over a fluence of 1 x 10 13 ions/cm 2 . On the 1 x 10 14 ions/cm 2 implanted collagen, no platelet activation was observed due to the influence of plasma proteins. >From the above, it is concluded that the decrease of adsorbed Fg and vWf caused the antithrombogenicity of He + ion implanted collagen with a fluence of 1 x 10 14 ions/cm 2 and that plasma protein adsorption took an important role repairing the graft surface

  14. The relationship between cellular adhesion and surface roughness in polystyrene modified by microwave plasma radiation

    Directory of Open Access Journals (Sweden)

    Biazar E

    2011-03-01

    Full Text Available Esmaeil Biazar1, Majid Heidari2, Azadeh Asefnezhad2, Naser Montazeri11Department of Chemistry, Islamic Azad University, Tonekabon Branch, Mazandaran; 2Department of Biomaterial Engineering, Faculty of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, IranBackground: Surface modification of medical polymers can improve biocompatibility. Pure polystyrene is hydrophobic and cannot provide a suitable environment for cell cultures. The conventional method for surface modification of polystyrene is treatment with plasma. In this study, conventional polystyrene was exposed to microwave plasma treatment with oxygen and argon gases for 30, 60, and 180 seconds.Methods and results: Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated clearly the presence of functional groups. Atomic force microscopic images of samples irradiated with inert and active gases indicated nanometric surface topography. Samples irradiated with oxygen plasma showed more roughness (31 nm compared with those irradiated with inert plasma (16 nm at 180 seconds. Surface roughness increased with increasing duration of exposure, which could be due to reduction of the contact angle of samples irradiated with oxygen plasma. Contact angle analysis showed reduction in samples irradiated with inert plasma. Samples irradiated with oxygen plasma showed a lower contact angle compared with those irradiated by argon plasma.Conclusion: Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation for samples radiated by oxygen plasma with increasing duration of exposure than those of normal samples.Keywords: surface topography, polystyrene, plasma treatment, argon, oxygen

  15. Impact of the surface roughness of AISI 316L stainless steel on biofilm adhesion in a seawater-cooled tubular heat exchanger-condenser.

    Science.gov (United States)

    García, Sergio; Trueba, Alfredo; Vega, Luis M; Madariaga, Ernesto

    2016-11-01

    The present study evaluated biofilm growth in AISI 316L stainless steel tubes for seawater-cooled exchanger-condensers that had four different arithmetic mean surface roughness values ranging from 0.14 μm to 1.2 μm. The results of fluid frictional resistance and heat transfer resistance regarding biofilm formation in the roughest surface showed increases of 28.2% and 19.1% respectively, compared with the smoothest surface. The biofilm thickness taken at the end of the experiment showed variations of up to 74% between the smoothest and roughest surfaces. The thermal efficiency of the heat transfer process in the tube with the roughest surface was 17.4% greater than that in the tube with the smoothest surface. The results suggest that the finish of the inner surfaces of the tubes in heat exchanger-condensers is critical for improving energy efficiency and avoiding biofilm adhesion. This may be utilised to reduce biofilm adhesion and growth in the design of heat exchanger-condensers.

  16. Surface energy of metal alloy nanoparticles

    Science.gov (United States)

    Takrori, Fahed M.; Ayyad, Ahmed

    2017-04-01

    The measurement of surface energy of alloy nanoparticles experimentally is still a challenge therefore theoretical work is necessary to estimate its value. In continuation of our previous work on the calculation of the surface energy of pure metallic nanoparticles we have extended our work to calculate the surface energy of different alloy systems, namely, Co-Ni, Au-Cu, Cu-Al, Cu-Mg and Mo-Cs binary alloys. It is shown that the surface energy of metallic binary alloy decreases with decreasing particle size approaching relatively small values at small sizes. When both metals in the alloy obey the Hume-Rothery rules, the difference in the surface energy is small at the macroscopic as well as in the nano-scale. However when the alloy deviated from these rules the difference in surface energy is large in the macroscopic and in the nano scales. Interestingly when solid solution formation is not possible at the macroscopic scale according to the Hume-Rothery rules, it is shown it may form at the nano-scale. To our knowledge these findings here are presented for the first time and is challenging from fundamental as well as technological point of views.

  17. Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase.

    Directory of Open Access Journals (Sweden)

    Kefeng Ni

    Full Text Available The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS-iron oxide nanoparticles (IONPs composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized.

  18. Adhesion of pineapple-leaf fiber to epoxy matrix: The role of surface treatments

    Directory of Open Access Journals (Sweden)

    Yusran Payae

    2009-07-01

    Full Text Available Natural fibers are considered to have potential use as reinforcing agents in polymer composite materials because of their principle benefits: moderate strength and stiffness, low cost, and be an environmental friendly, degradable, and renewablematerial. Due to their inherently hydrophilic nature, they are prone to absorb moisture, which can plasticise or weaken theadhesion of fibers to the surrounding matrix and by this affect the performance of composites used in atmospheric humidity,particularly at elevated temperatures. The surface treatments are often applied to the fiber to improve the bond strengthbetween the fibers and matrix. This work discussed the effect of sodium hydroxide (NaOH treatment and epoxy resin as acompatibilizing agent on interface properties of pineapple leaf fiber (PALF-epoxy composites. A single-fiber fragmentationtest coupled with data reduction technique was employed to assess interface quality in terms of apparent interfacial shearstrength (IFSS or a of untreated, NaOH, and epoxy resin treated PALFs-epoxy composites. Tensile properties of untreatedand treated PALFs were also examined. It was found that both treatments substantially increase a, corresponding to animproved level of adhesion. The improvement in the level of adhesion for the alkali and epoxy treated fiber composites wasdue to an increase in the physical bonding between the alkali treated fibers and the matrix, and due to a promoted compatibilitybetween the epoxy treated fibers and matrix, respectively.

  19. Cell adhesion and osteogenic differentiation on three-dimensional pillar surfaces.

    Science.gov (United States)

    Kaivosoja, Emilia; Suvanto, Pia; Barreto, Gonçalo; Aura, Susanna; Soininen, Antti; Franssila, Sami; Konttinen, Yrjö T

    2013-03-01

    We hypothesized that when compared with conventional two-dimensional (2D) cultures, substrates containing 3D micropillars would allow cells to grow at levels, activating their cytoskeleton to promote osteogenesis. Fibroblasts, osteoblast-like cells, and mesenchymal stem cells (MSCs) were studied. Planar substrates were compared with 200-nm-, 5-μm-, and 20-μm-high pillars of Ormocomp®, Si, diamond-like carbon, or TiO(2). Scanning electron microscopy and staining of actin cytoskeleton showed 7.5-h adhesion to pillar edges and 5-day stretching between adhesion contacts > 100-μm distances of fibroblast and MSC in 3D networks, whereas SaOS-2 cells adhered flatly and individually on horizontal and vertical surfaces. ERK and ROCK immunostaining at 14 and 21 days confirmed activation of the cytoskeleton. In contrast to expectations, success to induce osteogenesis was dominated by the cytocompatibility of the substrate over the 3D structure. This was shown using early alkaline phosphatase, intermediate osteopontin, and late mineralization markers, together with bone nodule formation, which were seen in planar substrates and low-profile TiO(2) pillars, but were poor in the 20-μm landscape. The lack of intercellular contacts seems to halt the osteogenesis-promoting effects of cytoskeletal organization and tension described earlier. Copyright © 2012 Wiley Periodicals, Inc.

  20. Environment-friendly adhesives for surface bonding of wood-based flooring using natural tannin to reduce formaldehyde and TVOC emission.

    Science.gov (United States)

    Kim, Sumin

    2009-01-01

    The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring using the natural tannin form bark in the wood. The natural wattle tannin adhesive were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. PVAc was added to the natural tannin adhesive to increase viscosity of tannin adhesive for surface bonding. For tannin/PVAc hybrid adhesives, 5%, 10%, 20% and 30% of PVAc to the natural tannin adhesives were added. tannin/PVAc hybrid adhesives showed better bonding than the commercial natural tannin adhesive with a higher level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method), field and laboratory emission cell (FLEC) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial the natural tannin adhesive and tannin/PVAc hybrid adhesives. By desiccator method and FLEC, the formaldehyde emission level of each adhesive showed the similar tendency. All adhesives satisfied the E(1) grade (below 1.5 mg/L) and E(0) grade (below 0.5 mg/L) with UV coating. VOC emission results by FLEC and VOC analyzer were different with the formaldehyde emission results. TVOC emission was slightly increased as adding PVAc.

  1. Bacterial adhesion to orthopaedic implant materials and a novel oxygen plasma modified PEEK surface

    NARCIS (Netherlands)

    Rochford, E. T. J.; Poulsson, A. H. C.; Salavarrieta Varela, J.; Lezuo, P.; Richards, R. G.; Moriarty, T. F.

    2014-01-01

    Despite extensive use of polyetheretherketone (PEEK) in biomedical applications, information about bacterial adhesion to this biomaterial is limited. This study investigated Staphylococcus aureus and Staphylococcus epidermidis adhesion to injection moulded and machined PEEK OPTIMA (R) using a

  2. In vitro and in vivo biofilm adhesion to esthetic coated arch wires and its correlation with surface roughness.

    Science.gov (United States)

    Taha, Mahasen; El-Fallal, Abeer; Degla, Heba

    2016-03-01

    To evaluate the in vitro ability of esthetic coated rectangular arch wires to retain oral biofilms and in vivo biofilm formation on these wires after 4 and 8 weeks of clinical use and to correlate the findings with the surface roughness of these wires. Three brands of esthetic coated nickel-titanium (NiTi) arch wires were selected. Arch wires retrieved after 4 and 8 weeks of intraoral use were obtained from 30 orthodontic patients. Surface roughness (SR) was assessed with an atomic force microscope. In vitro adhesion assays were performed using Streptococcus mutans (MS), Staphylococcus aureus, and Candida albicans. The amount of bacterial adhesion was quantified using the colony-count method. Paired t-test, analysis of variance, post hoc Tukey's test, and Pearson's correlation coefficient test were used for statistical analysis at the .05 level of significance. In vitro bacterial adhesion showed significant differences between wires in terms of MS adhesion (P  =  .01). All wires showed significant increases in SR (P  =  .001 after 4 weeks and .007 after 8 weeks) and biofilm adhesion (P  =  .0001 after 4 weeks and .045 after 8 weeks) after intraoral exposure. A significant positive correlation (P  =  .001 after 4 weeks and .05 after 8 weeks) was observed between these two variables in vivo, but the correlation was not significant for in vitro bacterial adhesion. SR and biofilm adhesion increased after intraoral use at all time intervals. There was a positive correlation between SR and biofilm adhesion in vivo only.

  3. Surface tension of polymer melts - experimental investigations of its effect on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    -polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEl, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies...

  4. Surface tension of polymer melts - experimental investigations of its effects on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Jankova Atanasova, Katja; Hansen, Hans Nørgaard

    -polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEI, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies...

  5. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-01-01

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

  6. Effect of surface energy on dispersion and mechanical properties of polymer/nanocrystalline cellulose nanocomposites.

    Science.gov (United States)

    Khoshkava, V; Kamal, M R

    2013-09-09

    Dispersion quality and polymer-filler interaction are important factors in determining the final properties of polymer nanocomposites. Surface energy of nanocrystalline cellulose (NCC) and some polymers (polypropylene, PP, and polylactic acid, PLA) was measured at room and high temperatures. NCC had higher polarity and surface energy than PP and PLA at room temperature but had a lower surface energy at higher temperatures. The effect of surface modification with alkenyl succinic anhydride (ASA) on NCC surface energy at room and high temperature was studied. Total surface energy of NCC was lowered after surface modification. Thermodynamic work of adhesion for PP/NCC and PLA/NCC was lowered by NCC surface modification. A thermodynamic analysis is proposed to estimate the dispersion energy, based on surface energy measurements at room and high temperatures. Also, a dispersion factor is defined to provide a quantitative indication of the dispersibility of nanoparticles in a polymer matrix under various conditions. The required dispersion energy was reduced by lowering the interfacial tension. On the other hand, it increased as the quality of NCC dispersion (i.e., the nanoparticle surface area) in the system was improved. Surface modification of NCC with ASA had a negative effect on the compatibility between NCC and PLA, whereas it had a positive influence on compatibility between PP and NCC.

  7. Controlling Gel Structure to Modulate Cell Adhesion and Spreading on the Surface of Microcapsules.

    Science.gov (United States)

    Zheng, Huizhen; Gao, Meng; Ren, Ying; Lou, Ruyun; Xie, Hongguo; Yu, Weiting; Liu, Xiudong; Ma, Xiaojun

    2016-08-03

    The surface properties of implanted materials or devices play critical roles in modulating cell behavior. However, the surface properties usually affect cell behaviors synergetically so that it is still difficult to separately investigate the influence of a single property on cell behavior in practical applications. In this study, alginate-chitosan (AC) microcapsules with a dense or loose gel structure were fabricated to understand the effect of gel structure on cell behavior. Cells preferentially adhered and spread on the loose gel structure microcapsules rather than on the dense ones. The two types of microcapsules exhibited nearly identical surface positive charges, roughness, stiffness, and hydrophilicity; thus, the result suggested that the gel structure was the principal factor affecting cell behavior. X-ray photoelectron spectroscopy analyses demonstrated that the overall percentage of positively charged amino groups was similar on both microcapsules. The different gel structures led to different states and distributions of the positively charged amino groups of chitosan, so we conclude that the loose gel structure facilitated greater cell adhesion and spreading mainly because more protonated amino groups remained unbound and exposed on the surface of these microcapsules.

  8. Bioinspired superhydrophobic poly(L-lactic acid) surfaces control bone marrow derived cells adhesion and proliferation.

    Science.gov (United States)

    Alves, Natália M; Shi, Jun; Oramas, Elena; Santos, José L; Tomás, Helena; Mano, João F

    2009-11-01

    The aptitude of a cell to adhere, migrate, and differentiate on a compact substrate or scaffold is important in the field of tissue engineering and biomaterials. It is well known that cell behavior can be controlled and guided through the change in micro- and nano-scale topographic features. In this work, we intend to demonstrate that special topographic features that control wettability may also have an important role in the biological performance of biodegradable substrates. Poly(L-lactic acid) surfaces with superhydrophobic characteristics were produced, based on the so-called Lotus effect, exhibiting dual micro- and nano-scale roughness. The water contact angle could be higher than 150 degrees and a value of that order could be kept even upon immersion in a simulated body fluid solution for more than 20 days. Such water repellent surfaces were found to prevent adhesion and proliferation of bone marrow derived cells previously isolated from the femurs of 6-week-old male Wistar rats, when compared with smoother surfaces prepared by simple solvent casting. Such results demonstrate that these superhydrophobic surfaces may be used to control cell behavior onto biodegradable substrates. (c) 2008 Wiley Periodicals, Inc.

  9. Evaluation of mechanism of non-thermal plasma effect on the surface of polypropylene films for enhancement of adhesive and hemo compatible properties

    Energy Technology Data Exchange (ETDEWEB)

    Navaneetha Pandiyaraj, K., E-mail: dr.knpr@gmail.com [Surface Engineering Laboratory, Department of Physics, Sri Shakthi Institute of Engineering and Technology, L& T by pass, Chinniyam Palayam (post), Coimbatore-641062 (India); Deshmukh, R.R. [Department of Physics, Institute of Chemical Technology, Matunga, Mumbai-400 019 (India); Arunkumar, A.; Ramkumar, M.C. [Surface Engineering Laboratory, Department of Physics, Sri Shakthi Institute of Engineering and Technology, L& T by pass, Chinniyam Palayam (post), Coimbatore-641062 (India); Ruzybayev, I.; Ismat Shah, S. [Department of Physics and Astronomy, Department of Materials Science and Engineering, University of Delaware, 208 Dupont Hall, Newark (United States); Su, Pi-Guey [Department of Chemistry, Chinese Culture University, Taipei 111, Taiwan (China); Periayah, Mercy Halleluyah; Halim, A.S. [School of Medical Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia)

    2015-08-30

    Highlights: • Investigated the mechanism of effect of various gaseous plasma treatments on the surface properties of Polypropylene (PP) films. • The improvement in surface energy is basically due to the incorporation of polar functional groups onto the PP films. • The extent of surface modification and hydrophobic recovery depends upon the type of plasma forming gas. • Due to the significant morphological and chemical changes induced by the gaseous plasma treatment, improved the blood compatibility as well as adhesive strength of the PP films. - Abstract: The hydro-carbon based polymers have attracted attention of scientists for its use in bio-medical field as various implants due to inherent flexibility. However, they have poor surface properties; particularly they have low surface energy (SE). Hence, blood components (platelets, blood proteins, etc.)-polymer surface interaction is the major concern when it comes in contact with blood. Thus, surface modification is required to develop the perfect antithrombogenic property without affecting the materials bulk. The present study describes the improvement in adhesive and blood compatible properties of polypropylene (PP) by low temperature (non-thermal) plasma of various gases such as Ar, O{sub 2}, air and Ar + O{sub 2} for biomedical applications. The changes in surface morphological, chemical and hydrophilic modification induced by the gaseous plasma treatment were analyzed by atomic force microscopy (AFM), X-ray photo electron spectroscopy (XPS), electron spin resonance (ESR) spectroscopy and contact angle measurements, respectively. Moreover, the stability of plasma effect was also studied for the different storage conditions. Variation in adhesive strength of the plasma treated PP film was studied by T-Peel and Lap-Shear strength tests. The blood compatibility of the surface modified PP films was investigated by in vitro analysis. It was found that gaseous plasma treatment improved the blood compatibility

  10. Enhancement of growth and osteogenic differentiation of MC3T3-E1 cells via facile surface functionalization of polylactide membrane with chitooligosaccharide based on polydopamine adhesive coating

    Energy Technology Data Exchange (ETDEWEB)

    Li, Huihua [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Luo, Chuang [Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Luo, Binghong, E-mail: tluobh@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Wen, Wei [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Wang, Xiaoying [Department of Biomedical Engineering, College of Life Science and Technology, Jinan University, Guangzhou 510632 (China); Ding, Shan [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China); Zhou, Changren, E-mail: tcrz9@jnu.edu.cn [Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632 (China)

    2016-01-01

    Graphical abstract: - Highlights: • COS was conveniently immobilized on PDLLA membrane based on PDOPA adhesive layer. • The hydrophilicity of PDLLA membrane was improved by modified with PDOPA and COS. • COS-functionalized PDLLA membrane is favorable to cell adhesion and proliferation. • COS-coated PDLLA membrane notably promote osteogenic differentiation of MC3T3-E1. - Abstract: To develop a chitooligosaccharide(COS)-functionalized poly(D,L-lactide) (PDLLA) membrane to enhance growth and osteogenic differentiation of MC3T3-E1 cells, firstly a thin polydopamine (PDOPA) layer was adhered to the PDLLA membrane via the self-polymerization and strong adhesion behavior of dopamine. Subsequently, COS was immobilized covalently on the resultant PDLLA/PDOPA composite membrane by coupling with PDOPA active coating. The successful immobilization of the PDOPA and COS was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Scanning electronic microscopy (SEM) and atomic force microscopy (AFM) results indicated that the surface topography and roughness of the membranes were changed, and the root mean square increased from 0.613 nm to 6.96 and 7.12 nm, respectively after coating PDOPA and COS. Water contact angle and surface energy measurements revealed that the membrane hydrophilicity was remarkably improved by surface modification. In vitro cells culture results revealed that the PDOPA- and COS-functionalized surfaces showed a significant increase in MC3T3-E1 cells adhesion, proliferation, osteogenic differentiation and alkaline phosphate activity compared to the pristine PDLLA substrate. Furthermore the COS-functionalized PDLLA membrane was more effectively at enhancing osteoblast activity than the PDOPA-functionalized PDLLA membrane.

  11. Adhesive properties and adhesive joints strength of graphite/epoxy composites

    Science.gov (United States)

    Rudawska, Anna; Stančeková, Dana; Cubonova, Nadezda; Vitenko, Tetiana; Müller, Miroslav; Valášek, Petr

    2017-05-01

    The article presents the results of experimental research of the adhesive joints strength of graphite/epoxy composites and the results of the surface free energy of the composite surfaces. Two types of graphite/epoxy composites with different thickness were tested which are used to aircraft structure. The single-lap adhesive joints of epoxy composites were considered. Adhesive properties were described by surface free energy. Owens-Wendt method was used to determine surface free energy. The epoxy two-component adhesive was used to preparing the adhesive joints. Zwick/Roell 100 strength device were used to determination the shear strength of adhesive joints of epoxy composites. The strength test results showed that the highest value was obtained for adhesive joints of graphite-epoxy composite of smaller material thickness (0.48 mm). Statistical analysis of the results obtained, the study showed statistically significant differences between the values of the strength of the confidence level of 0.95. The statistical analysis of the results also showed that there are no statistical significant differences in average values of surface free energy (0.95 confidence level). It was noted that in each of the results the dispersion component of surface free energy was much greater than polar component of surface free energy.

  12. Effects of surface hydration state and application method on the bond strength of self-etching adhesives to cut enamel.

    Science.gov (United States)

    Caneppele, Taciana Marco Ferraz; Torres, Carlos Rocha Carlos; Sassaki, Alan; Valdetaro, Fernanda; Fernandes, Ricardo Silva; Prieto de Freitas, Carolina; Batista, Graziela Ribeiro

    2012-02-01

    To evaluate the effect of surface hydration state and application method on the microtensile bond strength of one-step self-etching adhesives systems to cut enamel. One hundred ninety-five bovine teeth were used. The enamel on the buccal side was flattened with 600-grit SiC paper. For the control group, 15 teeth received Adper Single Bond 2, applied according to manufacturer's recommendations. The other specimens were divided into three groups according to the adhesive system used: Futura Bond M (FM; Voco), Clearfil S3 Bond (CS; Kuraray), and Optibond All in One (OA; Kerr). For each group, two hydration states were tested: D: blown dry with air; W: the excess of water was removed with absorbent paper. Two application methods were tested: P (passive): the adhesive was simply left on the surface; A (active): the adhesive was rubbed with an applicator point. A coat of Grandio composite resin (Voco) was applied on the surface. The teeth were sectioned to obtain enamel-resin sticks (1 x 1 mm), which underwent microtensile bond testing. The data in MPa were submitted to a three-way ANOVA and Tukey's test (α = 5%). The ANOVA showed significant differences for application method and the type of adhesive, but not for hydration state. For the application method, the results of Tukey's test were: P: 31.46 (± 7.09)a; A: 34.04 (± 7.19)b. For the type of adhesive, the results were: OA: 31.29 (± 7.05)a; CS: 32.28 (± 7.14)a; FM: 34.68 (± 7.17)b; different lower-case letters indicate statistically significant differences. Active application improved the bond strength to cut enamel. The adhesive Futurabond M showed the highest bond strength to cut enamel.

  13. Persistence of endodontic methacrylate-based cement residues on dentin adhesive surface treated with different chemical removal protocols.

    Science.gov (United States)

    Kuga, Milton Carlos; Só, Marcus Vinicius Reis; De Campos, Edson Alves; Faria, Gisele; Keine, Kátia Cristina; Dantas, Andrea Abi Rached; Faria, Norberto Batista

    2012-10-01

    The aim of this study was to evaluate the persistence of methacrylate-based cement residues on the dentin, after dentin surface cleaning with ethanol or acetone, with or without previous application of a dentin adhesive. Forty bovine crown fragments were obtained and the dentin surface was washed with 1.0 mL of 2.5% sodium hypochlorite (NaOCl), followed by 0.1 mL of 17% ethylenediaminetetraacetic acid application for 3 min, and final irrigation with 2.5% NaOCl. The specimens were air dried and resin-based cement was rubbed onto the dentine surface with a microbrush applicator. In 20 specimens, previously to cement, a dentin adhesive was applied in all surfaces. After 15 min, the surface was scrubbed with a cotton pellet and moistened with ethanol or acetone, compounding the following groups: G1-99.5% ethanol and G2-acetone, without previous use of dentin adhesive; G3-99.5% ethanol and G4-acetone, with previous use of dentin adhesive. The dentin surface was scrubbed until the cement residues could not be visually detected. Sections were then processed for scanning electron microscopy and evaluated at 500× magnification and scores were attributed to each image according to the area covered by residual sealer, and data were subjected to Kruskal-Wallis at 5% significance. The lower residue presence was observed in G3 (P = 0.005). All surface presented cement residues when acetone was used as cleaning solution (P = 0.0005). The cleaning solutions were unable to completely remove the cement residues from both surfaces. The ethanol used after previous application of the dentin adhesive promoted the lower presence of residues. Copyright © 2012 Wiley Periodicals, Inc.

  14. Improvement of the T-peel Strength of Polypropylene Adhesion Joints by Surface Photografting Pre-Treatment with Methyl Methacrylate

    Science.gov (United States)

    Balart, R.; Sánchez-Nácher, L.; Balart, J.; Fombuena, V.; España, J. M.

    2010-06-01

    Although polypropylene is one of the most used polymers at industrial level due to good balanced properties, it presents some restrictions in applications that require good adhesion properties as well as coating and painting. These restrictions are related to its non polar nature which leads to low wetting properties. So that, in most cases, it is necessary a previous surface pre-treatment in order to improve adhesion properties. These surface treatments could be physical or chemical. Among the wide variety of physical processes, plasma technologies are useful from both technical and environmental points of view. If we take into account economic considerations, chemical processes are interesting due to low cost equipment and procedures. In particular, we have used photografting of methyl methacrylate (MMA) monomer on polypropylene substrates with UV radiation and initiators. This process is useful to promote chemical modification of polypropylene surface by grafting MMA monomers into polypropylene polymer chains. Due to polarity of some groups in MMA monomers, it is possible to increase surface wettability thus promoting a remarkable increase in adhesion properties of polypropylene. In this work, changes in wettability of polypropylene surfaces in terms of the exposure time to UV radiation in presence of MMA monomers and initiators has been investigated. Furthermore, chemical changes have been characterized by FTIR analysis and mechanical performance of adhesion joints has been evaluated by T-peel tests.

  15. The Effects of Laser with Different Parameters and Crosshatching on Fibroblast Adhesion and Proliferation to Implant Surfaces.

    Science.gov (United States)

    Çelebi, Hakki; Arpacı, Pembegül Uyar; Çelik, Ilhami; Akman, Serhan

    To compare the adhesion and proliferation effect of HGF-1 cells on pure titanium disks when the surfaces are unprocessed (machined surfaces after slicing) or modified with a laser. Twenty-eight titanium disks were divided into four groups. Three surface topographies were created using an erbium fiber laser: group 1 (unidirectional application [no crosshatch]), group 2 (crosshatching in two directions), and group 3 (crosshatching in three directions). The samples in group 4 were unprocessed and served as controls. The surface roughness of samples was investigated with scanning electron microscopy (SEM) and measured with a mechanical surface profilometer. HGF-1 cell line was used to analyze the adhesion of fibroblasts on the sample surfaces. The authors used SEM, XTT, and acridine orange tests to determine the adhesion of HGF-1 onto specimen surfaces and the cell morphology after incubation for 72 hours. XTT results and surface roughness values for all specimens were analyzed using the Kruskal-Wallis test. Ra values of group 1 to group 4 (control) were 1.13, 0.26, 0.38, and 0.19, respectively. Crosshatching decreased the surface roughness values compared with unidirectional application (P = .003). Cell morphology observed in SEM showed that the elongation direction of cells resulted in all directions related with additional filopodia extentions within the crosshatch groups. Therefore, the highest cell viability was also detected in the three-directional crosshatch group (group 3) (P = .000) in XTT assay. According to the acridine orange test, higher cell numbers were seen in group 3, similar to the XTT findings (P = .86). Crosshatching significantly increased the cell-covered implant surfaces compared with the unidirectional group. Decreasing the surface Ra values via crosshatching helped spread the fibroblast over the implants in any direction, thus increasing cell proliferation and adhesion.

  16. Platelet adhesion and protein adsorption on silicone rubber surface by ozone-induced grafted polymerization with carboxybetaine monomer.

    Science.gov (United States)

    Zhou, Jun; Yuan, Jiang; Zang, Xiaopeng; Shen, Jian; Lin, Sicong

    2005-03-10

    Platelet adhesion and protein adsorption on the silicone rubber film grafted with N,N'-dimethyl-N-methacryloyloxyethyl-N-(2-carboxyethyl) ammonium (DMMCA) was studied. The grafting was carried out by means of ozone-induced method and was confirmed by ATR-FTIR and XPS investigations. The grafted films possessed relatively hydrophilic surface revealed by contact angle measurement. The blood compatibility of the grafted film was evaluated in vitro by platelet adhesion in platelet-rich plasma (PRP) and protein absorption in bovine fibrinogen (BFG) using silicone film as the reference. No substantial platelet adhesion was observed for the grafted films incubated in PRP for 60 and 180 min. The protein absorption was also significantly reduced after incubated in bovine fibrinogen for 60 min. Both the results indicated that the blood compatibility of silicone rubber was greatly improved by ozone-induced grafting of carboxybetaine zwitterionic polymer onto its surface.

  17. The neuroplastin adhesion molecules are accessory proteins that chaperone the monocarboxylate transporter MCT2 to the neuronal cell surface.

    Directory of Open Access Journals (Sweden)

    Marieangela C Wilson

    Full Text Available The neuroplastins np65 and np55 are two synapse-enriched immunoglobulin (Ig superfamily adhesion molecules that contain 3 and 2 Ig domains respectively. Np65 is implicated in long term, activity dependent synaptic plasticity, including LTP. Np65 regulates the surface expression of GluR1 receptor subunits and the localisation of GABA(A receptor subtypes in hippocampal neurones. The brain is dependent not only on glucose but on monocarboxylates as sources of energy. The. monocarboxylate transporters (MCTs 1-4 are responsible for the rapid proton-linked translocation of monocarboxylates including pyruvate and lactate across the plasma membrane and require association with either embigin or basigin, proteins closely related to neuroplastin, for plasma membrane expression and activity. MCT2 plays a key role in providing lactate as an energy source to neurons.Here we use co-transfection of neuroplastins and monocarboxylate transporters into COS-7 cells to demonstrate that neuroplastins can act as ancillary proteins for MCT2. We also show that Xenopus laevis oocytes contain endogenous neuroplastin and its knockdown with antisense RNA reduces the surface expression of MCT2 and associated lactate transport. Immunocytochemical studies show that MCT2 and the neuroplastins are co-localised in rat cerebellum. Strikingly neuroplastin and MCT2 are enriched in the same parasagittal zebrin II-negative stripes.These data strongly suggest that neuroplastins act as key ancillary proteins for MCT2 cell surface localisation and activity in some neuronal populations, thus playing an important role in facilitating the uptake of lactate for use as a respiratory fuel.

  18. Using QCM-D to study the adhesion of human gingival fibroblasts on implant surfaces.

    Science.gov (United States)

    Westas, Emma; Svanborg, Lory Melin; Wallin, Patric; Bauer, Brigitte; Ericson, Marica B; Wennerberg, Ann; Mustafa, Kamal; Andersson, Martin

    2015-10-01

    Sealing the soft tissue-implant interface is one of the key issues in preventing transcutaneous implant-associated infections. A promising surface modification for improving osseointegration and possibly soft tissue integration is to coat the implant surface with hydroxyapatite (HA) nanoparticles. When new implant materials are developed, their ability to facilitate cell attachment and spreading are commonly investigated in vitro to establish their potential for good in vivo performance. However, commonly used techniques, such as microscopy methods, are time consuming, invasive, and subjective. This is the first study using quartz crystal microbalance with dissipation monitoring, where the real-time adhesion of biopsy-derived human gingival fibroblasts onto titanium and nanostructured HA was investigated. Experiments were performed for at least 16 h, and we found that cellular attachment and spreading kinetics can be followed in situ by observing the change in dissipation and frequency with time. Interestingly, a correlation between cell coverage and the magnitude of dissipation shift reached at the end of the experiment was found, but no such trend was observed for the frequency. Furthermore, the level of cell coverage was found to influence the cellular attachment and spreading behavior. No difference in cell response to the two surface types, Ti and nanostructured HA, was found. © 2015 Wiley Periodicals, Inc.

  19. The effect of surface preparation on the behaviour of double strap adhesive joints with thick steel adherents

    DEFF Research Database (Denmark)

    Anyfantis, K.N.; Tsouvalis, N.G.

    2009-01-01

    One of the major factors determining the integrity of an adhesive bond is the preparation of the bonding surfaces. The present study is an experimental investigation of the effect of the surface preparation procedure on the response of a steel-to-steel double strap adhesive joint. Two procedures...... for preparing the bonding surfaces are investigated, namely grit blasting (GB) and simple sandpaper (SP). The behaviour of the joints, in terms of the force-displacement and strains-displacement responses was monitored and compared for both cases. The joints with SP surface preparation exhibited slightly lower...... stiffness and lower strength than the joints with GB surface preparation, while the latter failed at a lower displacement. In both cases, failure initiated at the free edges of the joints and the dominating failure mode was interfacial. In addition to the above experimental measurements, results are also...

  20. Influence of growth conditions on adhesion of yeast Candida spp. and Pichia spp. to stainless steel surfaces.

    Science.gov (United States)

    Tomičić, Ružica; Raspor, Peter

    2017-08-01

    An understanding of adhesion behavior of Candida and Pichia yeast under different environmental conditions is key to the development of effective preventive measures against biofilm-associated infection. Hence in this study we investigated the impact of growth medium and temperature on Candida and Pichia adherence using stainless steel (AISI 304) discs with different degrees of surface roughness (Ra = 25.20-961.9 nm), material typical for the food processing industry as well as medical devices. The adhesion of the yeast strains to stainless steel surfaces grown in Malt Extract broth (MEB) or YPD broth at three temperatures (7 °C, 37 °C, 43 °C for Candida strains and 7 °C, 27 °C, 32 °C for Pichia strains) was assessed by crystal violet staining. The results showed that the nutrient content of medium significantly influenced the quantity of adhered cells by the tested yeasts. Adhesion of C. albicans and C. glabrata on stainless steel surfaces were significantly higher in MEB, whereas for C. parapsilosis and C. krusei it was YPD broth. In the case with P. pijperi and P. membranifaciens, YPD broth was more effective in promoting adhesion than MEB. On the other hand, our data indicated that temperature is a very important factor which considerably affects the adhesion of these yeast. There was also significant difference in cell adhesion on all types of stainless steel surfaces for all tested yeast. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Comparative study of nJ- and μJ-energy level femtosecond lasers: evaluation of flap adhesion strength, stromal bed quality, and tissue responses.

    Science.gov (United States)

    Riau, Andri K; Liu, Yu-Chi; Lwin, Nyein C; Ang, Heng P; Tan, Neil Y S; Yam, Gary H F; Tan, Donald T; Mehta, Jodhbir S

    2014-04-24

    To compare flap adhesion strength, stromal bed quality, and tissue responses after flap preparation using nJ- and μJ-energy level femtosecond lasers. All corneal flaps were created by either VisuMax laser (μJ-energy level) or femto-LDV (nJ-energy level). Flap adhesion strength in the rabbits was measured with a tension meter 1 and 2 months postoperatively. To investigate tissue responses to laser delivery, immunofluorescence staining and TUNEL assay were performed 4 and 24 hours postoperatively. To assess flap bed smoothness, human donor corneas were used. Surface irregularities were graded based on scanning electron microscopy results. The flap adhesion strength in the VisuMax group at month 1 and 2 was 16.95 ± 1.45 kPa and 18.33 ± 1.81 kPa, respectively; and 12.31 ± 4.15 kPa and 13.85 ± 4.78 kPa in the LDV group, respectively. No significant difference was found between the groups. Fibronectin and apoptotic cells were largely absent at the central incision site in the LDV group, but were present in the VisuMax group. The smoothness of flap beds appeared similar for both groups. An observer scored the VisuMax group 8.00 ± 1.00 and the LDV group 7.33 ± 0.58 (P = 0.387). The flap adhesion strength increased over time after treatment with both lasers. The nJ-energy pulses produced minimal wound healing reaction and apoptotic cells along the incision plane. The application of an nJ-energy laser, which can incise the cornea without inducing significant damage to cells and wound healing reaction, offers great potential at reducing scarring following incisional laser stromal surgery. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  2. Reduction of initial corrosion rate and improvement of cell adhesion through surface modification of biodegradable Mg alloy

    Science.gov (United States)

    Han, Hyung-Seop; Lee, Sun Hee; Kim, Won-Joo; Jeon, Hojeong; Seok, Hyun-Kwang; Ahn, Jae-Pyung; Kim, Yu-Chan

    2015-01-01

    In this study, the surface modification of biodegradable pure Magnesium and Mg-5wt%Ca-1wt%Zn alloy was performed through immersion in HBSS, inorganic salt solution and cell media to reduce initial hydrogen evolution and improve cell adhesion. The formation of different CaP-like coatings from immersion of pure Mg and Mg alloy were observed using Cryo FIB analysis and their performances were measured through cell adhesion, quantification of released Mg ions, and cell cytotoxicity assays. The coating layers displayed significant reduction of initial corrosion rate, and cell adhesion for both pure Mg and Mg alloy appeared to be influenced by the amino acids and proteins in the cell media. In general, Mg alloy showed a denser coating layer with higher Ca contents, resulting in greater reduction of initial corrosion rate and improved cell adhesion, when compared to pure Mg. This is due to saturation of Ca around the corrosion site that provided much favorable environmental condition to produce denser calcium phosphate coating mixture. The result from this study suggests that the surface modification of biodegradable Mg alloy by immersion in alkaline solutions can be utilized to obtain ideal biodegradable orthopedic implant material with reduced initial hydrogen evolution rate and improved cell adhesion.

  3. SURFACE ENERGY BALANCE OVER ORANGE ORCHARD USING SURFACE RENEWAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Salvatore Barbagallo

    2009-12-01

    Full Text Available Reliable estimation of surface sensible and latent heat flux is the most important process to appraise energy and mass exchange among atmosphere and biosphere. In this study the surface energy fluxes were measured over an irrigated orange orchard during 2005-2008 monitoring periods using a Surface Renewal- Energy Balance approach. The experimental area is located in a representative orchard growing area of eastern Sicily (Italy. The performance of Surface Renewal (SR analysis for estimating sensible heat flux (H was analysed and evaluated in terms of correlation with H fluxes from the eddy covariance (EC method. Study revealed that the mean available energy (RN- G and latent heat flux (LE were of about 300 W m-2 and 237 W m-2, respectively, during dry periods and unstable-case atmospheric conditions. The estimated crop coefficient Kc values for the orchard crop averaged close to 0.80, which is considerably higher than previous FAO studies that found the value to be 0.65 for citrus with 70% of ground cover. The intercepted photosynthetically active radiation (LI PAR by the crop was measured and relationships between LAI and crop coefficient (Kc were established.

  4. Ion induced modification of polymers at energies between 100 keV and 1 GeV applied for optical waveguides and improved metal adhesion

    International Nuclear Information System (INIS)

    Rueck, D.M.

    2000-01-01

    Polymers are a class of materials widely used for a broad field of applications. Ion irradiation ranging from several eV to GeV is a quite efficient tool to modify the properties of polymers like wettability, optical properties, adhesion between metal and polymer surfaces. In this paper ion induced chemical changes of polymers will be discussed in relation to the modified macroscopic properties. In the field of optical telecommunication, polymers are discussed as a new class of materials for the fabrication of passive optical devices. Ion irradiation is a promising method to generate structures with a modified index of refraction, which is necessary for the guidance of light with different wavelengths in optical devices. Modified optical properties of different polymers under ion irradiation will be discussed. Analytical investigations like infrared measurements and measurement of the outgassing reaction products during irradiation will be discussed to interpret the chemical changes of the polymers. Metallization of polymers is of interest in several fields of application like for multilayer systems in microtechnology or casings for radiation shielding for example. Ion beam mixing at low energies is a promising method to improve the metal/polymer adhesion. Also ion irradiation at high energies applied to a metal/polymer multilayer can improve the adhesion of a metal layer to a polymer surface, if not sufficient. Different metal/polymer systems will be presented as well as specific applications

  5. Beyond molecular recognition: using a repulsive field to tune interfacial valency and binding specificity between adhesive surfaces.

    Science.gov (United States)

    Santore, Maria M; Zhang, Jun; Srivastava, Sudhanshu; Rotello, Vincent M

    2009-01-06

    Surface-bound biomolecular fragments enable "smart" materials to recognize cells and other particles in applications ranging from tissue engineering and medical diagnostics to colloidal and nanoparticle assembly. Such smart surfaces are, however, limited in their design to biomolecular selectivity. This feature article demonstrates, using a completely nonbiological model system, how specificity can be achieved for particle (and cell) binding, employing surface designs where immobilized nanoscale adhesion elements are entirely nonselective. Fundamental principles are illustrated by a model experimental system where 11 nm cationic nanoparticles on a planar negative silica surface interact with flowing negative silica microspheres having 1.0 and 0.5 microm diameters. In these systems, the interfacial valency, defined as the number of cross-bonds needed to capture flowing particles, is tunable through ionic strength, which alters the range of the background repulsion and therefore the effective binding strength of the adhesive elements themselves. At high ionic strengths where long-range electrostatic repulsions are screened, single surface-bound nanoparticles capture microspheres, defining the univalent regime. At low ionic strengths, competing repulsions weaken the effective nanoparticle adhesion so that multiple nanoparticles are needed for microparticle capture. This article discusses important features of the univalent regime and then illustrates how multivalency produces interfacial-scale selectivity. The arguments are then generalized, providing a possible explanation for highly specific cell binding in nature, despite the degeneracy of adhesion molecules and cell types. The mechanism for the valency-related selectivity is further developed in the context of selective flocculation in the colloidal literature. Finally, results for multivalent binding are contrasted with the current thinking for interfacial design and the presentation of adhesion moieties on

  6. Surface Plasmon-Assisted Solar Energy Conversion.

    Science.gov (United States)

    Dodekatos, Georgios; Schünemann, Stefan; Tüysüz, Harun

    2016-01-01

    The utilization of localized surface plasmon resonance (LSPR) from plasmonic noble metals in combination with semiconductors promises great improvements for visible light-driven photocatalysis, in particular for energy conversion. This review summarizes the basic principles of plasmonic photocatalysis, giving a comprehensive overview about the proposed mechanisms for enhancing the performance of photocatalytically active semiconductors with plasmonic devices and their applications for surface plasmon-assisted solar energy conversion. The main focus is on gold and, to a lesser extent, silver nanoparticles in combination with titania as semiconductor and their usage as active plasmonic photocatalysts. Recent advances in water splitting, hydrogen generation with sacrificial organic compounds, and CO2 reduction to hydrocarbons for solar fuel production are highlighted. Finally, further improvements for plasmonic photocatalysts, regarding performance, stability, and economic feasibility, are discussed for surface plasmon-assisted solar energy conversion.

  7. Surface-modified nanoparticles as a new, versatile, and mechanically robust nonadhesive coating : Suppression of protein adsorption and bacterial adhesion

    NARCIS (Netherlands)

    Holmes, P. F.; Currie, E. P. K.; Thies, J. C.; van der Mei, H. C.; Busscher, H. J.; Norde, W.

    2009-01-01

    The synthesis of surface-modified silica nanoparticles, chemically grafted with acrylate and poly(ethylene glycol) (PEG) groups, and the ability of the resulting crosslinked coatings to inhibit protein adsorption and bacterial adhesion are explored. Water contact angles, nanoindentation, and atomic

  8. Plasma Polymerized Thin Films of Maleic Anhydride and 1,2-methylenedioxybenzene for Improving Adhesion to Carbon Surfaces

    DEFF Research Database (Denmark)

    Drews, Joanna Maria; Goutianos, Stergios; Kingshott, Peter

    2007-01-01

    Low power 2-phase AC plasma polymerization has been used to surface modify glassy carbon substrates that are used as an experimental model for carbon fibers in reinforced composites. In order to probe the role of carboxylic acid density on the interfacial adhesion strength a combination...

  9. Effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhi [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Department of Bone and Joint Surgery, The affiliated hospital of Luzhou Medical College, Luzhou 646000 (China); Qing, Quan [Sichuan College of Traditional Chinese Medicine, Mianyang 621000 (China); Regenerative Medicine Research Center, West China Hospital of Sichuan University, Chengdu 610041 (China); Chen, Xi; Liu, Cheng-Jun; Luo, Jing-Cong [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China); Hu, Jin-Lian [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Qin, Ting-Wu, E-mail: tingwuqin@hotmail.com [State Key Laboratory of Biotherapy, West China Hospital of Sichuan University, Chengdu 610041 (China)

    2016-12-01

    Highlights: • The shapes of tenocytes varied when seeded on different surface of scaffolds. • Tenocytes were flat on smooth surface and spindle on micro-grooved surface. • Tenocytes were ellipse or spindle on porous surface. • Tenocytes got varying adhesion shape and elongation index on varying surfaces. • The tenocyte survival on porous surface was superior to the other two groups. - Abstract: The purpose of this study was to investigate the effects of scaffold surface morphology on cell adhesion and survival rate in vitreous cryopreservation of tenocyte-scaffold constructs. Tenocytes were obtained from tail tendons of rats. Polydimethylsiloxane (PDMS) was used to fabricate three types of scaffolds with varying surface morphological characteristics, i.e., smooth, micro-grooved, and porous surfaces, respectively. The tenocytes were seeded on the surfaces of the scaffolds to form tenocyte-scaffold constructs. The constructs were cryopreserved in a vitreous cryoprotectant (CPA) with a multi-step protocol. The cell adhesion to scaffolds was observed with electronic scanning microscopy (SEM). The elongation index of the living tenocytes and ratio of live/dead cell number were examined based on a live/dead dual fluorescent staining technique, and the survival rate of tenocytes was studied with flow cytometry (FC). The results showed the shapes of tenocytes varied between the different groups: flat or polygonal (on smooth surface), spindle (on micro-grooved surface), and spindle or ellipse (on porous surface). After thawing, the porous surface got the most living tenocytes and a higher survival rate, suggesting its potential application for vitreous cryopreservation of engineered tendon constructs.

  10. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    Energy Technology Data Exchange (ETDEWEB)

    Godoy-Gallardo, Maria, E-mail: maria.godoy.gallardo@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Guillem-Marti, Jordi, E-mail: jordi.guillem.marti@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Sevilla, Pablo, E-mail: psevilla@euss.es [Department of Mechanics, Escola Universitària Salesiana de Sarrià (EUSS), C/ Passeig de Sant Bosco, 42, 08017 Barcelona (Spain); Manero, José M., E-mail: jose.maria.manero@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); Gil, Francisco J., E-mail: francesc.xavier.gil@upc.edu [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Centre for Research in NanoEngineering (CRNE) — UPC, C/ Pascual i Vila 15, 08028 Barcelona (Spain); and others

    2016-02-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  11. Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

    International Nuclear Information System (INIS)

    Godoy-Gallardo, Maria; Guillem-Marti, Jordi; Sevilla, Pablo; Manero, José M.; Gil, Francisco J.

    2016-01-01

    Bacterial infection in dental implants along with osseointegration failure usually leads to loss of the device. Bioactive molecules with antibacterial properties can be attached to titanium surfaces with anchoring molecules such as silanes, preventing biofilm formation and improving osseointegration. Properties of silanes as molecular binders have been thoroughly studied, but research on the biological effects of these coatings is scarce. The aim of the present study was to determine the in vitro cell response and antibacterial effects of triethoxysilypropyl succinic anhydride (TESPSA) silane anchored on titanium surfaces. X-ray photoelectron spectroscopy confirmed a successful silanization. The silanized surfaces showed no cytotoxic effects. Gene expression analyses of Sarcoma Osteogenic (SaOS-2) osteoblast-like cells cultured on TESPSA silanized surfaces reported a remarkable increase of biochemical markers related to induction of osteoblastic cell differentiation. A manifest decrease of bacterial adhesion and biofilm formation at early stages was observed on treated substrates, while favoring cell adhesion and spreading in bacteria–cell co-cultures. Surfaces treated with TESPSA could enhance a biological sealing on implant surfaces against bacteria colonization of underlying tissues. Furthermore, it can be an effective anchoring platform of biomolecules on titanium surfaces with improved osteoblastic differentiation and antibacterial properties. - Highlights: • TESPSA silane induces osteoblast differentiation. • TESPSA reduces bacterial adhesion and biofilm formation. • TESPSA is a promising anchoring platform of biomolecules onto titanium.

  12. Influence of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires

    Science.gov (United States)

    Asiry, Moshabab A.; AlShahrani, Ibrahim; Almoammar, Salem; Durgesh, Bangalore H.; Kheraif, Abdulaziz A. Al; Hashem, Mohamed I.

    2018-02-01

    Aim. To investigate the effect of epoxy, polytetrafluoroethylene (PTFE) and rhodium surface coatings on surface roughness, nano-mechanical properties and biofilm adhesion of nickel titanium (Ni-Ti) archwires Methods. Three different coated (Epoxy, polytetrafluoroethylene (PTFE) and rhodium) and one uncoated Ni-Ti archwires were evaluated in the present study. Surface roughness (Ra) was assessed using a non-contact surface profilometer. The mechanical properties (nano-hardness and elastic modulus) were measured using a nanoindenter. Bacterial adhesion assays were performed using Streptococcus mutans (MS) and streptococcus sobrinus (SS) in an in-vitro set up. The data obtained were analyzed using analyses of variance, Tukey’s post hoc test and Pearson’s correlation coefficient test. Result. The highest Ra values (1.29 ± 0.49) were obtained for epoxy coated wires and lowest Ra values (0.29 ± 0.16) were obtained for the uncoated wires. No significant differences in the Ra values were observed between the rhodium coated and uncoated archwires (P > 0.05). The highest nano-hardness (3.72 ± 0.24) and elastic modulus values (61.15 ± 2.59) were obtained for uncoated archwires and the lowest nano-hardness (0.18 ± 0.10) and elastic modulus values (4.84 ± 0.65) were observed for epoxy coated archwires. No significant differences in nano-hardness and elastic modulus values were observed between the coated archwires (P > 0.05). The adhesion of Streptococcus mutans (MS) to the wires was significantly greater than that of streptococcus sobrinus (SS). The epoxy coated wires demonstrated an increased adhesion of MS and SS and the uncoated wires demonstrated decreased biofilm adhesion. The Spearman correlation test showed that MS and SS adhesion was positively correlated with the surface roughness of the wires. Conclusion. The different surface coatings significantly influence the roughness, nano-mechanical properties and biofilm adhesion parameters of the archwires. The

  13. Cell adhesion over two distinct surfaces varied with chemical and mechanical properties

    International Nuclear Information System (INIS)

    Huang, Chih-Ling; Liao, Jiunn-Der; Yang, Chia-Fen; Chang, Chia-Wei; Ju, Ming-Shaung; Lin, Chou-Ching K.

    2009-01-01

    Chitosan is widely recognized as a natural and proper scaffold material; however, as a base substrate, it shows little promotion effect for the growth of cultured fibroblast cells. In this study, chitosan in a film form was prepared and used as a cell-culturing matrix, followed by patterning the evaporated Au upon it. Micro-scale Au clusters of ∼ 150 μm in diameter and ∼ 20 nm in thickness were then patterned and adhered upon the chitosan matrix. Physical and chemical properties of Au/chitosan were characterized. In particular, nano-indentation with dynamic contact module was applied to measure the nano-hardness of the tailored surfaces on Au/chitosan. Fibroblast cells were thereafter cultured on Au/chitosan. Experimental results demonstrated that as compared with the chitosan matrix, Au clusters and their boundary area exhibited favorable to promote cell adhesion, spreading, and growth. As well, nano-hardness on the boundary area of Au/chitosan significantly enhanced, while the cultured fibroblast cells aggregated upon Au clusters and the boundary area. In combination with the possible chemical and mechanical changes resulted by the evaporation of Au clusters upon the chitosan matrix, a selectively-enhanced Au/chitosan to promote fibroblast cells proliferation was created. Such design is anticipated for enabling a surface for scaffold materials with the cell-guidable function.

  14. Engineering of silicon surfaces at the micro- and nanoscales for cell adhesion and migration control

    Directory of Open Access Journals (Sweden)

    Torres-Costa V

    2012-02-01

    Full Text Available Vicente Torres-Costa1, Gonzalo Martínez-Muñoz2, Vanessa Sánchez-Vaquero3, Álvaro Muñoz-Noval1, Laura González-Méndez3, Esther Punzón-Quijorna1,4, Darío Gallach-Pérez1, Miguel Manso-Silván1, Aurelio Climent-Font1,4, Josefa P García-Ruiz3, Raúl J Martín-Palma11Department of Applied Physics, 2Department of Computer Science, 3Department of Molecular Biology, 4Centre for Micro Analysis of Materials, Universidad Autónoma de Madrid, Madrid, SpainAbstract: The engineering of surface patterns is a powerful tool for analyzing cellular communication factors involved in the processes of adhesion, migration, and expansion, which can have a notable impact on therapeutic applications including tissue engineering. In this regard, the main objective of this research was to fabricate patterned and textured surfaces at micron- and nanoscale levels, respectively, with very different chemical and topographic characteristics to control cell–substrate interactions. For this task, one-dimensional (1-D and two-dimensional (2-D patterns combining silicon and nanostructured porous silicon were engineered by ion beam irradiation and subsequent electrochemical etch. The experimental results show that under the influence of chemical and morphological stimuli, human mesenchymal stem cells polarize and move directionally toward or away from the particular stimulus. Furthermore, a computational model was developed aiming at understanding cell behavior by reproducing the surface distribution and migration of human mesenchymal stem cells observed experimentally.Keywords: surface patterns, silicon, hMSCs, ion-beam patterning

  15. The relationship between cellular adhesion and surface roughness for polyurethane modified by microwave plasma radiation

    Directory of Open Access Journals (Sweden)

    Heidari S

    2011-04-01

    Full Text Available Saeed Heidari Keshel1, S Neda Kh Azhdadi2, Azadeh Asefnezhad2, Mohammad Sadraeian3, Mohamad Montazeri4, Esmaeil Biazar51Stem Cell Preparation Unit, Eye Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences; 2Department of Biomaterial Engineering, Faculty of Biomedical Engineering, Science and Research Branch - Islamic Azad University; 3Young Researchers Club, Islamic Azad University, North Tehran Branch, Tehran; 4Faculty of Medical Sciences, Babol University of Medical Sciences, Babol; 5Department of Chemistry, Islamic Azad University, Tonekabon, IranAbstract: Surface modification of medical polymers is carried out to improve biocompatibility. In this study, conventional polyurethane was exposed to microwave plasma treatment with oxygen and argon gases for 30 seconds and 60 seconds. Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated the presence of functional groups. Atomic force microscope images of samples irradiated with inert and active gases indicated the nanometric topography of the sample surfaces. Samples irradiated by oxygen plasma indicated high roughness compared with those irradiated by inert plasma for the different lengths of time. In addition, surface roughness increased with time, which can be due to a reduction of contact angle of samples irradiated by oxygen plasma. Contact angle analysis indicated a reduction in samples irradiated with both types of plasma. However, samples irradiated with oxygen plasma indicated lower contact angle compared with those irradiated by argon plasma. Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation among samples radiated by oxygen plasma for longer than for normal samples.Keywords: surface topography, polyurethane, plasma treatment, cellular investigation

  16. Fabrication of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using electrolysis plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jianbing, E-mail: jianbingmeng@126.com; Dong, Xiaojuan; Wei, Xiuting; Yin, Zhanmin [School of Mechanical Engineering, Shandong University of Technology, Zibo, 255049 (China)

    2015-04-15

    An anti-adhesion surface with a water contact angle of 167° was fabricated on aluminium samples of rubber plastic moulds by electrolysis plasma treatment using mixed electrolytes of C{sub 6}H{sub 5}O{sub 7}(NH{sub 4}){sub 3} and Na{sub 2}SO{sub 4}, followed by fluorination. To optimise the fabrication conditions, several important processing parameters such as the discharge voltage, discharge time, concentrations of supporting electrolyte and stearic acid ethanol solution were examined systematically. Using scanning electron microscopy (SEM) to analyse surfaces morphology, micrometer scale pits, and protrusions were found on the surface, with numerous nanometer mastoids contained in the protrusions. These binary micro/nano-scale structures, which are similar to the micro-structures of soil-burrowing animals, play a critical role in achieving low adhesion properties. Otherwise, the anti-adhesion behaviours of the resulting samples were analysed by the atomic force microscope (AFM), Fourier-transform infrared spectrophotometer (FTIR), electrons probe micro-analyzer (EPMA), optical contact angle meter, digital Vickers microhardness (Hv) tester, and electronic universal testing. The results show that the electrolysis plasma treatment does not require complex processing parameters, using a simple device, and is an environment-friendly and effective method. Under the optimised conditions, the contact angle (CA) for the modified anti-adhesion surface is up to 167°, the sliding angle (SA) is less than 2°, roughness of the sample surface is only 0.409μm. Moreover, the adhesion force and H{sub v} are 0. 9KN and 385, respectively.

  17. Fabrication of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using electrolysis plasma treatment

    International Nuclear Information System (INIS)

    Meng, Jianbing; Dong, Xiaojuan; Wei, Xiuting; Yin, Zhanmin

    2015-01-01

    An anti-adhesion surface with a water contact angle of 167° was fabricated on aluminium samples of rubber plastic moulds by electrolysis plasma treatment using mixed electrolytes of C 6 H 5 O 7 (NH 4 ) 3 and Na 2 SO 4 , followed by fluorination. To optimise the fabrication conditions, several important processing parameters such as the discharge voltage, discharge time, concentrations of supporting electrolyte and stearic acid ethanol solution were examined systematically. Using scanning electron microscopy (SEM) to analyse surfaces morphology, micrometer scale pits, and protrusions were found on the surface, with numerous nanometer mastoids contained in the protrusions. These binary micro/nano-scale structures, which are similar to the micro-structures of soil-burrowing animals, play a critical role in achieving low adhesion properties. Otherwise, the anti-adhesion behaviours of the resulting samples were analysed by the atomic force microscope (AFM), Fourier-transform infrared spectrophotometer (FTIR), electrons probe micro-analyzer (EPMA), optical contact angle meter, digital Vickers microhardness (Hv) tester, and electronic universal testing. The results show that the electrolysis plasma treatment does not require complex processing parameters, using a simple device, and is an environment-friendly and effective method. Under the optimised conditions, the contact angle (CA) for the modified anti-adhesion surface is up to 167°, the sliding angle (SA) is less than 2°, roughness of the sample surface is only 0.409μm. Moreover, the adhesion force and H v are 0. 9KN and 385, respectively

  18. Fabrication of anti-adhesion surfaces on aluminium substrates of rubber plastic moulds using electrolysis plasma treatment

    Science.gov (United States)

    Meng, Jianbing; Dong, Xiaojuan; Wei, Xiuting; Yin, Zhanmin

    2015-04-01

    An anti-adhesion surface with a water contact angle of 167° was fabricated on aluminium samples of rubber plastic moulds by electrolysis plasma treatment using mixed electrolytes of C6H5O7(NH4)3 and Na2SO4, followed by fluorination. To optimise the fabrication conditions, several important processing parameters such as the discharge voltage, discharge time, concentrations of supporting electrolyte and stearic acid ethanol solution were examined systematically. Using scanning electron microscopy (SEM) to analyse surfaces morphology, micrometer scale pits, and protrusions were found on the surface, with numerous nanometer mastoids contained in the protrusions. These binary micro/nano-scale structures, which are similar to the micro-structures of soil-burrowing animals, play a critical role in achieving low adhesion properties. Otherwise, the anti-adhesion behaviours of the resulting samples were analysed by the atomic force microscope (AFM), Fourier-transform infrared spectrophotometer (FTIR), electrons probe micro-analyzer (EPMA), optical contact angle meter, digital Vickers microhardness (Hv) tester, and electronic universal testing. The results show that the electrolysis plasma treatment does not require complex processing parameters, using a simple device, and is an environment-friendly and effective method. Under the optimised conditions, the contact angle (CA) for the modified anti-adhesion surface is up to 167°, the sliding angle (SA) is less than 2°, roughness of the sample surface is only 0.409μm. Moreover, the adhesion force and Hv are 0. 9KN and 385, respectively.

  19. Multi-functional and redundant roles of Borrelia burgdorferi outer surface proteins in tissue adhesion, colonization, and complement evasion.

    Directory of Open Access Journals (Sweden)

    Jennifer A Caine

    2016-10-01

    Full Text Available Borrelia burgdorferi is the causative agent of Lyme disease in the U.S., with at least 25,000 cases reported to the CDC each year. B. burgdorferi is thought to enter and exit the bloodstream to achieve rapid dissemination to distal tissue sites during infection. Travel through the bloodstream requires evasion of immune surveillance and pathogen clearance in the host, a process at which B. burgdorferi is adept. B. burgdorferi encodes greater than 19 adhesive outer surface proteins many of which have been found to bind to host cells or components of the extracellular matrix. Several others bind to host complement regulatory factors, in vitro. Production of many of these adhesive proteins is tightly regulated by environmental cues, and some have been shown to aid in vascular interactions and tissue colonization, as well as survival in the blood, in vivo. Recent work has described multifaceted and redundant roles of B. burgdorferi outer surface proteins in complement component interactions and tissue targeted adhesion and colonization, distinct from their previously identified in vitro binding capabilities. Recent insights into the multifunctional roles of previously well characterized outer surface proteins such as BBK32, DbpA, CspA, and OspC have changed the way we think about the surface proteome of these organisms during the tick-mammal lifecycle. With the combination of new and old in vivo models and in vitro techniques, the field has identified distinct ligand binding domains on BBK32 and DbpA that afford tissue colonization or blood survival to B. burgdorferi. In this review we describe the multifunctional and redundant roles of many adhesive outer surface proteins of B. burgdorferi in tissue adhesion, colonization, and bloodstream survival that, together, promote the survival of Borrelia spp. throughout maintenance in their multi-host lifestyle.

  20. Adhesion in microelectronics

    CERN Document Server

    Mittal, K L

    2014-01-01

    This comprehensive book will provide both fundamental and applied aspects of adhesion pertaining to microelectronics in a single and easily accessible source. Among the topics to be covered include; Various theories or mechanisms of adhesionSurface (physical or chemical) characterization of materials as it pertains to adhesionSurface cleaning as it pertains to adhesionWays to improve adhesionUnraveling of interfacial interactions using an array of pertinent techniquesCharacterization of interfaces / interphasesPolymer-polymer adhesionMetal-polymer adhesion  (metallized polymers)Polymer adhesi

  1. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.; Levin, Eugene

    1993-01-01

    A new global potential energy surface (PES) is being generated for O(P-3) + H2 yields OH + H. This surface is being fit using the rotated Morse oscillator method, which was used to fit the previous POL-CI surface. The new surface is expected to be more accurate and also includes a much more complete sampling of bent geometries. A new study has been undertaken of the reaction N + O2 yields NO + O. The new studies have focused on the region of the surface near a possible minimum corresponding to the peroxy form of NOO. A large portion of the PES for this second reaction has been mapped out. Since state to state cross sections for the reaction are important in the chemistry of high temperature air, these studies will probably be extended to permit generation of a new global potential for reaction.

  2. Surface modification of SU-8 for metal/SU-8 adhesion using RF plasma treatment for application in thermopile detectors

    Science.gov (United States)

    Ashraf, Shakeel; Mattsson, Claes G.; Fondell, Mattis; Lindblad, Andreas; Thungström, Göran

    2015-08-01

    This article reports on plasma treatment of SU-8 epoxy in order to enhance adhesive strength for metals. Its samples were fabricated on standard silicon wafers and treated with (O2 and Ar) RF plasma at a power of 25 W at a low pressure of (3 × 10-3 Torr) for different time spans (10-70 s). The sample surfaces were characterized in terms of contact angle, surface (roughness and chemistry) and using a tape test. During the contact angle measurement, it was observed that the contact angle was reduced from 73° to 5° (almost wet) and 23° for (O2 and Ar) treated samples, respectively. The root mean square surface roughness was significantly increased by 21.5% and 37.2% for (O2 and Ar) treatment, respectively. A pattern of metal squares was formed on the samples using photolithography for a tape test. An adhesive tape was applied to the samples and peeled off at 180°. The maximum adhesion results, more than 90%, were achieved for the O2-treated samples, whereas the Ar-treated samples showed no change. The XPS study shows the formation of new species in the O2-treated sample compared to the Ar-treated samples. The high adhesive results were due to the formation of hydrophilic groups and new O2 species in the O2-treated samples, which were absent in Ar-treated samples.

  3. Further Investigation Into the Use of Laser Surface Preparation of Ti-6Al-4V Alloy for Adhesive Bonding

    Science.gov (United States)

    Palmieri, Frank L.; Crow, Allison; Zetterberg, Anna; Hopkins, John; Wohl, Christopher J.; Connell, John W.; Belcher, Tony; Blohowiak, Kay Y.

    2014-01-01

    Adhesive bonding offers many advantages over mechanical fastening, but requires robust materials and processing methodologies before it can be incorporated in primary structures for aerospace applications. Surface preparation is widely recognized as one of the key steps to producing robust and predictable bonds. This report documents an ongoing investigation of a surface preparation technique based on Nd:YAG laser ablation as a replacement for the chemical etch and/or abrasive processes currently applied to Ti-6Al-4V alloys. Laser ablation imparts both topographical and chemical changes to a surface that can lead to increased bond durability. A laser based process provides an alternative to chemical-immersion, manual abrasion, and grit blast process steps which are expensive, hazardous, environmentally unfriendly, and less precise. In addition, laser ablation is amenable to process automation, which can improve reproducibility to meet quality standards for surface preparation. An update on work involving adhesive property testing, surface characterization, surface stability, and the effect of laser surface treatment on fatigue behavior is presented. Based on the tests conducted, laser surface treatment is a viable replacement for the immersion chemical surface treatment processes. Testing also showed that the fatigue behavior of the Ti-6Al-4V alloy is comparable for surfaces treated with either laser ablation or chemical surface treatment.

  4. Early gametocytes of the malaria parasite Plasmodium falciparum specifically remodel the adhesive properties of infected erythrocyte surface

    DEFF Research Database (Denmark)

    Tibúrcio, Marta; Silvestrini, Francesco; Bertuccini, Lucia

    2013-01-01

    endothelial cells. In conclusion, these results identify specific differences in molecular and cellular mechanisms of host cell remodelling and in adhesive properties, leading to clearly distinct host parasite interplays in the establishment of sequestration of stage I gametocytes and of asexual trophozoites.......In Plasmodium falciparum infections the parasite transmission stages, the gametocytes, mature in 10 days sequestered in internal organs. Recent studies suggest that cell mechanical properties rather than adhesive interactions play a role in sequestration during gametocyte maturation. It remains...... to ultrastructurally and biochemically analyse parasite-induced modifications on the red blood cell surface and to measure their functional consequences on adhesion to human endothelial cells. This work revealed that stage I gametocytes are able to deform the infected erythrocytes like asexual parasites, but do...

  5. Obtaining evapotranspiration and surface energy fluxes with ...

    African Journals Online (AJOL)

    In this study, SEBAL (Surface Energy Balance Algorithm for Land), a remote sensing based evapotranspiration model, has been applied with Landsat ETM+ sensor for the estimation of actual ... The land uses in this study area consists of irrigated agriculture, rain-fed agriculture and livestock grazing. The obtained results ...

  6. Potential energy surface of alanine polypeptide chains

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.

    2006-01-01

    The multidimensional potential energy surfaces of the peptide chains consisting of three and six alanine (Ala) residues have been studied with respect to the degrees of freedom related to the twist of these molecules relative to the peptide backbone (these degrees of freedom are responsible...

  7. Surface-Segregation-Induced Nanopapillae on FDTS-Blended PDMS Film and Implications in Wettability, Adhesion, and Friction Behaviors.

    Science.gov (United States)

    Pan, Zihe; Peng, Ran; Tang, Juntao; Chen, Li; Cheng, Fangqin; Zhao, Boxin

    2018-02-28

    Polymer composites have been extensively used to tune the surface property (e.g., wettability, friction, and adhesion) for its advantages of cost-effectiveness, high efficiency, and ease of fabrication. In this work, different amount of trichloro(1H,1H,2H,2H-perfluorooctyl)silane (FDTS) was added into poly(dimethylsiloxane) elastomer to prepare polymer composite films and were selected as a model to illustrate the effects of surface segregation on surface topology, wettability, friction, and adhesion. The results show that the added FDTS forms aggregations and increasing the content of FDTS leads to the difficulty of air bubble elimination, increase in viscosity, and drop in transparency. Driven by the differences of chemical potential, FDTS aggregations migrate to the air-polymer interface, resulting in surface enrichment and formation of nanopapillae (1-200 nm). This phenomenon becomes more significant with the increment in FDTS. The change in surface composition and structure generates profound effects on wettability, friction, and adhesion. The addition of FDTS makes the surface relatively oleophobic and further increasing the content of FDTS does not helpful in improving the oleophobicity due to the notable aggregation. Friction forces first grow with the increasing content of FDTS and then decline after the maximum point at 1.0 wt % of FDTS, which is attributed to the generated regular larger nanopappillae at high concentration. However, these larger nanopapillae lead to the increase in adhesion because more interactions are formed. The findings demonstrate the behaviors of FDTS in polymer composites and provide important guidance for controlling the formation of nanostructures via aggregation and phase segregation and exploring their implications on surface properties.

  8. A widely applicable method to fabricate underwater superoleophobic surfaces with low oil-adhesion on different metals by a femtosecond laser

    Science.gov (United States)

    Zhang, Jingzhou; Chen, Feng; Yang, Qing; Yong, Jiale; Huo, Jinglan; Fang, Yao; Hou, Xun

    2017-09-01

    In this paper, a one-step way to realize underwater superoleophobicity and low oil-adhesion on various metals by femtosecond laser ablation was proposed. The laser ablated aluminum surface showed hierarchical rough microstructure composed of abundant micro-holes and nano-particles. The oil contact angle on the as-prepared Al surface reached up to 157° and the oil sliding angle was just 7° to a 1,2-dichloroethane droplet in water. In addition, various oils including chloroform, hexadecane, n-dodecane, decane, liquid paraffin, and petroleum ether also showed underwater superoleophobicity on the structured aluminum surface. What's more, other metals such as iron, copper, molybdenum, and stainless steel were ablated, respectively, through the same method. Due to the formation of rough microstructures and their intrinsic high surface energy, they all exhibited remarkable underwater ultralow oil-adhesive superoleophobicity. Such one-fit-all method with anti-oil-pollution can be a suit for an ocean of metals, which undoubtedly will be used in underwater precise instruments, such as vessels, underwater detectors, and oil-water separation device.

  9. Tensile bond strength of an adhesive resin cement to different alloys having various surface treatments.

    Science.gov (United States)

    Abreu, Amara; Loza, Maria A; Elias, Augusto; Mukhopadhyay, Siuli; Looney, Stephen; Rueggeberg, Frederick A

    2009-02-01

    The ability of a resin cement to bond to a restorative alloy is critical for maximal crown retention to nonideal preparations. Surface treatment and metal type may have an important role in optimizing resin-to-metal strength. The purpose of this study was to examine the effect of surface pretreatment on the tensile strength of base and noble metals bonded using a conventional resin cement. Cylindrical plastic rods (9.5 mm in diameter), cast in base (Rexillium NBF) or noble metal (IPS d.SIGN 53), were divided into rods 10 mm in length (n=10-12). Specimens were heated in a porcelain furnace to create an oxide layer. Test specimens were further subjected to airborne-particle abrasion (50-microm Al(2)O(3) particles) alone or with the application of a metal primer (Alloy Primer). Similarly treated rod ends were joined using resin cement (RelyX ARC), thermocycled (x500, 5 degrees -55 degrees C) and stored (24 hours, 37 degrees C) before debonding using a universal testing machine. Debond strength and failure site were recorded. Rank-based ANOVA for unbalanced designs was used to test for significant interaction (alpha=.050). Each pair of treatments was compared separately for each metal (Bonferroni-adjusted significance level of .0083, overall error rate for comparisons, .05). The 2 metals were compared separately for each of the 3 treatments using an adjusted significance level of .017, maintaining an overall error rate of .05. A multinomial logit model was used to describe the effect of metal type and surface pretreatment on failure site location (alpha=.05). Interaction between metal type and surface pretreatment was significant for stress values (P=.019). Metal type did not significantly affect tensile bond strength for any of the compared surface pretreatments. Metal primer significantly improved tensile bond strength for each metal type. Most failures tended to occur as either adhesive or mixed in nature. Metal primer application significantly enhanced tensile bond

  10. Potential energy surface of triplet O4.

    Science.gov (United States)

    Paukku, Yuliya; Varga, Zoltan; Truhlar, Donald G

    2018-03-28

    We present a global ground-state potential energy surface (PES) for the triplet spin state of O 4 that is suitable for treating high-energy vibrational-rotational energy transfer and collision-induced dissociation in electronically adiabatic spin-conserving O 2 -O 2 collisions. The surface is based on MS-CASPT2/maug-cc-pVTZ electronic structure calculations with scaled external correlation; the active space has 16 electrons in 12 orbitals. The global ground-state potential energy surface was fitted by a many-body approach with an accurate O-O pairwise interaction and a fit of the many-body interaction potential to 10 180 electronic structure data points. The many-body fit is based on permutationally invariant polynomials in terms of bond-order functions of the six interatomic distances; the bond-order functions are mixed exponential-Gaussian functions. The geometries calculated and used for the fit include geometry scans corresponding to dissociative and vibrationally excited diatom-diatom collisions of O 2 , scans corresponding to O 3 interacting with O, additional geometries identified by running trajectories, and geometries along linear synchronous transit paths connecting randomly selected points. The global O 4 PES includes subsurfaces describing the interaction of diatomic molecules with other diatomic molecules or interactions of triatomic molecules and an atom. The interaction of ozone with a ground-state oxygen atom occurs on the triplet O 4 surface, and our surface includes high-energy points with O 3 -O geometries as well as O 2 -O 2 geometries and O 2 -O-O geometries.

  11. Influence of nitriding atmosphere on the modification of surface titanium with focus on the behavior of blood platelets adhesion

    International Nuclear Information System (INIS)

    Vitoriano, J.O.; Alves, C.; Braz, D.C.; Camara, R.B.G.; Rocha, H.A.O.

    2014-01-01

    The present study aimed to analyze the influence of surface modification of titanium on the adhesion of blood platelets, through techniques of adhesion and morphological analyzes. Discs of titanium grade II received different surface treatments with plasma of Ar + N 2 + H 2 and Ar + H 2 , forming two experimental groups including only polished samples used as standard. Before and after treatment the samples were characterized according to topography, crystalline structure and wettability, using atomic force microscopy, X-ray diffraction, Raman spectroscopy and testing of sessile drop, respectively. Platelet rich plasma (PRP) was applied on the modified surfaces in a culture plates. Images obtained by electron microscopy of adhered platelets were analyzed to verify the behavior of platelets in the different experimental conditions. (author)

  12. Surface functionalization of titanium substrates with chitosan-lauric acid conjugate to enhance osteoblasts functions and inhibit bacteria adhesion.

    Science.gov (United States)

    Zhao, Lu; Hu, Yan; Xu, Dawei; Cai, Kaiyong

    2014-07-01

    Orthopedic implants failures are generally related to poor osseointegration and/or bacterial infection in clinical application. Surface functionalization of an implant is one promising alternative for enhancing osseointegration and/or reducing bacterial infection, thus ensuring the long term survival of the implant. In this study, titanium (Ti) substrates were surface functionalized with a polydopamine (PDOP) film as an intermediate layer for post-immobilization of chitosan-lauric acid (Chi-LA) conjugate. Chi-LA conjugate was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and hydrogen proton nuclear magnetic resonance (NMR) spectrometer, respectively. Lauric acid (LA), a natural saturated fatty acid, was used mainly due to its good antibacterial property. Scanning electron microscopy (SEM) and water contact angle measurements were employed to detect the morphology changes and surface wettability of Ti substrates. The results suggested that Chi-LA conjugate was successfully immobilized onto the surfaces of Ti substrates. In vitro tests confirmed that the cell adhesion, cell viability, intracellular alkaline phosphatase activity and mineralization capacity of osteoblasts were remarkably improved when cultured onto Chi-LA surface functionalized Ti substrates. Antibacterial assay against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) showed that the Chi-LA modified Ti substrates efficiently inhibited the adhesion and growth of bacteria. Overall, this study developed a promising approach to fabricate functional Ti-based orthopedic implants, which could enhance the biological functions of osteoblasts and concurrently reduce bacteria adhesion. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Energy Efficienct Processes for Making Tackifier Dispersions used to make Pressure Sensitive Adhesives

    Energy Technology Data Exchange (ETDEWEB)

    Rakesh Gupta

    2006-07-26

    The primary objective of this project was to develop an energy efficient, environmentally friendly and low cost process (compared to the current process) for making tackifier dispersions that are used to make pressure-sensitive adhesives. These adhesives are employed in applications such as self-adhesive postage stamps and disposable diapers and are made by combining the tackifier dispersion with a natural or synthetic rubber latex. The current process for tackifier dispersion manufacture begins by melting a (plastic) resin and adding water to it in order to form a water-in-oil emulsion. This is then converted to an oil-in-water emulsion by phase inversion in the presence of continuous stirring. The resulting emulsion is the tackifier dispersion, but it is not concentrated and the remaining excess water has to be transported and removed. The main barrier that has to be overcome in the development of commercial quality tackifier dispersions is the inability to directly emulsify resin in water due to the very low viscosity of water as compared to the viscosity of the molten resin. In the present research, a number of solutions were proposed to overcome this barrier, and these included use of different mixer types to directly form the emulsion from the molten resin but without going through a phase inversion, the idea of forming a solid resin-in-water suspension having the correct size and size distribution but without melting of the resin, and the development of techniques of making a colloidal powder of the resin that could be dispersed in water just prior to use. Progress was made on each of these approaches, and each was found to be feasible. The most appealing solution, though, is the last one, since it does not require melting of the resin. Also, the powder can be shipped in dry form and then mixed with water in any proportion depending on the needs of the process. This research was conducted at Argonne National Laboratory, and it was determined the new process

  14. Molecular dynamics study on the effects of stamp shape, adhesive energy, and temperature on the nanoimprint lithography process

    International Nuclear Information System (INIS)

    Kang, Ji-Hoon; Kim, Kwang-Seop; Kim, Kyung-Woong

    2010-01-01

    Molecular dynamics simulations of nanoimprint lithography (NIL) were performed to investigate the effects of three critical process parameters in NIL: stamp shape, adhesive energy between the stamp and polymer film, and imprint temperature. The proposed simulation model of the NIL process consists of an amorphous SiO 2 stamp with a line pattern, an amorphous poly(methylmethacrylate) film, and a Si substrate under the periodic boundary condition in the horizontal direction to simulate a real NIL process imprinting periodical line patterns. The behavior of polymer deformation and the effects of adhesion on pattern transfer were investigated by observing the deformation process, calculating the imprint and separation forces, and analyzing the density and stress distribution inside the polymer film. In addition, their dependency on the process parameters is also discussed with reference to the changes in pattern shape, adhesive energy between the stamp and polymer atoms, and imprint temperature of the polymer film. During the imprint process, the rectangular pattern shows inferior cavity filling and higher stress concentration compared to trapezoidal and triangular patterns because it requires much larger flow and deformation of the polymer film. Low imprint temperature also produces high stress concentration and large imprint force due to the lower fluidity of polymer film. In the separation process, the rectangular pattern generates the largest separation force and causes the most serious defects of the transferred pattern and even the polymer film, while the triangular pattern shows the most satisfactory pattern transfer. In addition, the adhesive energy between the stamp and the polymer film also strongly influences the adhesion between the stamp and the polymer film. Low adhesive energy reduces the separation force of the stamp and transferred pattern defects, and therefore enhances the quality of pattern transfer.

  15. Analysis of Self-Adhesive Resin Cement Microshear Bond Strength on Leucite-Reinforced Glass-Ceramic with/without Pure Silane Primer or Universal Adhesive Surface Treatment.

    Science.gov (United States)

    Lee, Yoon; Kim, Jae-Hoon; Woo, Jung-Soo; Yi, Young-Ah; Hwang, Ji-Yun; Seo, Deog-Gyu

    2015-01-01

    To evaluate the microshear bond strength (μSBS) of self-adhesive resin (SA) cement on leucite-reinforced glass-ceramic using silane or universal adhesive. Ceramic blocks were etched with 9.5% hydrofluoric acid and divided into three groups (n = 16): (1) negative control (NC) without treatment; (2) Single Bond Universal (SBU); (3) RelyX Ceramic Primer as positive control (PC). RelyX Unicem resin cement was light-cured, and μSBS was evaluated with/without thermocycling. The μSBS was analyzed using one-way analysis of variance. The fractured surfaces were examined using stereomicroscopy and scanning electron microscopy (SEM). Without thermocycling, μSBS was highest for PC (30.50 MPa ± 3.40), followed by SBU (27.33 MPa ± 2.81) and NC (20.18 MPa ± 2.01) (P 0.05). PC and NC predominantly fractured by cohesive failure within the ceramic and mixed failure, respectively. SBU treatment improves μSBS between SA cement and glass ceramics, but to a lower value than PC, and the improvement is eradicated by thermocycling. NC exhibited the lowest μSBS, which remained unchanged after thermocycling.

  16. Effect of skin surface lipid on the skin permeation of lidocaine from pressure sensitive adhesives.

    Science.gov (United States)

    Cheng, Y H; Hosoya, O; Sugibayashi, K; Morimoto, Y

    1994-12-01

    Pressure sensitive adhesives (PSA) tapes containing different concentrations of lidocaine were prepared by a general casting method using styrene-isoprene-styrene block copolymer, and the in vitro skin permeation of lidocaine from each tape was evaluated using diffusion cell and excised hairless rat skin. The skin permeation was proportionally increased by up to 40% lidocaine in the PSA tape and did not change after this concentration. Although the bending point of the steady-state flux via skin concentration curve was found at 40%, saturated concentration or solubility of lidocaine in the tape was estimated to be about 20% by differential scanning calorimetry (DSC) measurement. In addition, the steady-state flux of lidocaine through skin from water or silicone fluid suspension (92 or 120 micrograms/cm2.h, respectively) was very similar to those of 40, 50 and 60% tapes (105, 101 and 112 micrograms/cm2.h, respectively). Decrease in the concentration in tapes during the permeation experiment explained only part of these phenomena. To analyze them further, the drug free PSA tape with or without (control) skin surface lipid was affixed to 50% lidocaine PSA tape for 48 h, and the amount of lidocaine crystal in the layered tapes was measured by DSC. The amount was found to be lower in the lipid-containing tape than in the lipid-free tape, suggesting that skin surface lipid can dissolve lidocaine crystal or solid in PSA tape to decrease its thermodynamic activity. Thus it is important to follow the concentration and thermodynamic activity of lidocaine in PSA tape, skin and the interface between the two layers to exactly assess its skin permeation flux.

  17. Mechanisms of adhesion in geckos.

    Science.gov (United States)

    Autumn, Kellar; Peattie, Anne M

    2002-12-01

    The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (θ) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (W(GS)) is in fact proportional to (1 + cosθ), and only for θ > 60°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 μm displacement yielded a very large adhesive force of 200 microNewton (μN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.

  18. Surface analysis with low energy ion scattering

    International Nuclear Information System (INIS)

    Taglauer, E.; Heiland, W.

    1976-01-01

    Principles and applications of low energy ion scattering for surface analysis are presented. Basic features are the binary collision concept, the scattering cross-sections and the ion neutralization process. The potential and the limitations of the method are outlined. Some pertinent experimental aspects are considered. In a number of examples the performance of the technique is demonstrated for qualitative composition analysis and for studies of surface structures. Finally a few comparisons are made with other techniques, such as AES, LEED, or SIMS. (orig.) [de

  19. Surface energy and wettability of polymers light-cured by two different systems.

    Science.gov (United States)

    Namen, Fatima Maria; Ferrandini, Eduardo; Galan Junior, João

    2011-10-01

    This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. Filtek Z350 (3M ESPE), Admira (VOCO) and Grandio (VOCO) resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100) using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard) that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

  20. Surface energy-tunable iso decyl acrylate based molds for low pressure-nanoimprint lithography

    Science.gov (United States)

    Tak, Hyowon; Tahk, Dongha; Jeong, Chanho; Lee, Sori; Kim, Tae-il

    2017-10-01

    We presented surface energy-tunable nanoscale molds for unconventional lithography. The mold is highly robust, transparent, has a minimized haze, does not contain additives, and is a non-fluorinated isodecyl acrylate and trimethylolpropane triacrylate based polymer. By changing the mixing ratio of the polymer components, the cross-linking density, mechanical modulus, and surface energy (crucial factors in low pressure ((1-2) × 105 N m-2) low pressure-nanoimprint lithography (LP-NIL)), can be controlled. To verify these properties of the molds, we also characterized the surface energy by measuring the contact angles and calculating the work of adhesion among the wafer, polymer film, and mold for successful demolding in nanoscale structures. Moreover, the molds showed high optical clarity and precisely tunable mechanical and surface properties, capable of replicating sub-100 nm patterns by thermal LP-NIL and UV-NIL.

  1. Various Surface Treatments to Implant Provisional Restorations and Their Effect on Epithelial Cell Adhesion: A Comparative In Vitro Study.

    Science.gov (United States)

    Luchinskaya, Darya; Du, Rong; Owens, David M; Tarnow, Dennis; Bittner, Nurit

    2017-02-01

    The aim of this in vitro study was to investigate the ability of epithelial cells to attach to or proliferate on various mechanical or chemical surface treatments of an implant provisional material. Polyethyl methacrylate discs 10 mm in diameter and ∼0.2 to 0.75 mm in width were used in the study. Experimental discs were treated with either a mechanical (pumice, varnish for shine, or high polishing) or a chemical agent (alcohol, chlorhexidine, or steam) to provide cleaning and/or polishing. Using primary human epidermal keratinocytes, experiments were performed to test the adhesion or proliferation of cells on the discs with various surface treatments. Scanning electron microscope analysis, rhodamine staining, and cell counting using a hemocytometer corroborated all findings and illustrated that the highest cell adhesion was found to be in the smooth surface treatment groups and the poorest adhesion was found to be in the rough surface groups and chemical treatment group. Within the limitations of this study, the following clinical protocol is recommended for finishing, polishing, and disinfecting implant provisional restorations: coarse, medium, fine pumice → high polishing (if desired) → steam. It is recommended to avoid applying varnish in the perimucosal area near the epithelium. This study could establish the most appropriate way to handle provisional restorations in the peri-implant sulcus for improved soft tissue health, esthetics, and long-term stability.

  2. Effect of two different polishing systems on fluoride release, surface roughness and bacterial adhesion of newly developed restorative materials.

    Science.gov (United States)

    Bayrak, Gokcen Deniz; Sandalli, Nuket; Selvi-Kuvvetli, Senem; Topcuoglu, Nursen; Kulekci, Guven

    2017-11-12

    To evaluate the effects of two different polishing systems on fluoride release, surface roughness and bacterial adhesion of five restorative materials MATERIALS AND METHODS: The study groups were comprised of five different restorative materials, Beautifil II (B); GCP Glass Fill (G); Amalgomer CR (A); Dyract XP (D); Fuji IX GP (F) and 21 specimens were prepared from each material. Each group was divided into three subgroups according to the polishing system: Mylar (control) (C), Sof-lex (S), and Enhance-Pogo (EP). The amount of fluoride release was measured using a fluoride ion-selective electrode and surface roughness was investigated with a profilometer. Bacterial adhesion on the materials was evaluated by optical density readouts for S.mutans on a spectrophotometer. The highest amount of fluoride was released from specimens in the S subgroup of group G during all measurement days. Surface roughness values were significantly lower in subgroup C than the other polishing systems in all study groups except group G (P restorative materials especially in glass ionomer-based materials. This article stated that polishing promoted a significant increase of fluoride release on restorative materials especially in glass ionomer-based materials. Further, proper polishing systems must be chosen according to the structure and composition of materials to provide the best clinical benefits in terms of fluoride release, surface roughness and bacterial adhesion. © 2017 Wiley Periodicals, Inc.

  3. Adhesion Control between Resist and Photomask Blank

    Science.gov (United States)

    Kurihara, Masaaki; Hatakeyama, Sho; Yoshida, Kouji; Abe, Makoto; Totsukawa, Daisuke; Morikawa, Yasutaka; Mohri, Hiroshi; Hoga, Morihisa; Hayashi, Naoya; Ohtani, Hiroyuki; Fujihira, Masamichi

    2009-06-01

    Most problems in photomask fabrication such as pattern collapse, haze, and cleaning damage are related to the behavior of surfaces and interfaces of resists, opaque layers, and quartz substrates. Therefore, it is important to control the corresponding surface and interface energies in photomask fabrication processes. In particular, adhesion analysis in microscopic regions is strongly desirable to optimize material and process designs in photomask fabrication. We applied the direct peeling (DP) method with a scanning probe microscope (SPM) tip and measured the adhesion of resist patterns on Cr and quartz surfaces for photomask process optimization. We also studied the effect of tip shape on the reproducibility of adhesion measurements and the dependence of collapse behavior on the resist profile. We measured lateral forces between the resulting collapsed resist pillar and the Cr or the quartz surface before and after the sliding and related these observed lateral forces to the static and kinetic frictional forces, respectively. We also studied the effect of surface modification of the Cr and quartz surfaces with silanization reagents on adhesion measured with the DP method. Resist adhesion could be controlled by surface modification using silanes. We also discuss the relationship between the adhesion observed with the DP method and the properties of the modified surfaces including water contact angles and local adhesive forces measured from force-distance curves with an SPM.

  4. Energy redistribution in diatomic molecules on surfaces

    International Nuclear Information System (INIS)

    Asscher, M.; Somorjai, G.A.

    1984-04-01

    Translational and internal degrees of freedom of a scattered beam of NO molecules from a Pt(111) single crystal surface were measured as a function of scattering angle and crystal temperature in the range 450 to 1250K. None of the three degrees of freedom were found to fully accommodate to the crystal temperature, the translational degree being the most accommodated and the rotational degree of freedom the least. A precursor state model is suggested to account for the incomplete accommodation of translational and vibrational degrees of freedom as a function of crystal temperature and incident beam energy. The vibrational accommodation is further discussed in terms of a competition between desorption and vibrational excitation processes, thus providing valuable information on the interaction between vibrationally excited molecules and surfaces. Energy transfer into rotational degrees of freedom is qualitatively discussed

  5. Computed potential energy surfaces for chemical reactions

    Science.gov (United States)

    Walch, Stephen P.

    1994-01-01

    Quantum mechanical methods have been used to compute potential energy surfaces for chemical reactions. The reactions studied were among those believed to be important to the NASP and HSR programs and included the recombination of two H atoms with several different third bodies; the reactions in the thermal Zeldovich mechanism; the reactions of H atom with O2, N2, and NO; reactions involved in the thermal De-NO(x) process; and the reaction of CH(squared Pi) with N2 (leading to 'prompt NO'). These potential energy surfaces have been used to compute reaction rate constants and rates of unimolecular decomposition. An additional application was the calculation of transport properties of gases using a semiclassical approximation (and in the case of interactions involving hydrogen inclusion of quantum mechanical effects).

  6. Porous titania surfaces on titanium with hierarchical macro- and mesoporosities for enhancing cell adhesion, proliferation and mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Han, Guang [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Müller, Werner E.G.; Wang, Xiaohong [ERC Advanced Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Duesbergweg 6, D-55128 Mainz (Germany); Lilja, Louise [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden); Department of Physics, Chemistry and Biology, Linköping University, SE-581 83 Linköping (Sweden); Shen, Zhijian, E-mail: shen@mmk.su.se [Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)

    2015-02-01

    Titanium received a macroporous titania surface layer by anodization, which contains open pores with average pore diameter around 5 μm. An additional mesoporous titania top layer following the contour of the macropores, of 100–200 nm thickness and with a pore diameter of 10 nm, was formed by using the evaporation-induced self-assembly (EISA) method with titanium (IV) tetraethoxide as the precursor. A coherent laminar titania surface layer was thus obtained, creating a hierarchical macro- and mesoporous surface that was characterized by high-resolution electron microscopy. The interfacial bonding between the surface layers and the titanium matrix was characterized by the scratch test that confirmed a stable and strong bonding of titania surface layers on titanium. The wettability to water and the effects on the osteosarcoma cell line (SaOS-2) proliferation and mineralization of the formed titania surface layers were studied systematically by cell culture and scanning electron microscopy. The results proved that the porous titania surface with hierarchical macro- and mesoporosities was hydrophilic that significantly promoted cell attachment and spreading. A synergistic role of the hierarchical macro- and mesoporosities was revealed in terms of enhancing cell adhesion, proliferation and mineralization, compared with the titania surface with solo scale topography. - Highlights: • We developed a hierarchical macro- and mesoporous surface layer on titanium. • New surface layer was strong enough to sustain on implant surface. • New surface owned better surface wettability. • New surface can promote SaOS-2 cell adhesion, proliferation and mineralization. • Synergistic effects on cell responses occur when two porous structures coexist.

  7. Elaboration of highly hydrophobic polymeric surface — a potential strategy to reduce the adhesion of pathogenic bacteria?

    Energy Technology Data Exchange (ETDEWEB)

    Poncin-Epaillard, F., E-mail: fabienne.poncin-epaillard@univ-lemans.fr [Institut des Molécules et Matériaux du Mans (IMMM), département Polymères, Colloïdes et Interfaces, UMR CNRS 6283 Université LUNAM, av. O. Messiaen, 72085 Le Mans (France); Herry, J.M. [INRA-AgroParisTech, UMR 1319 MICALIS, équipe B2HM, 25 avenue de la République, 91300 Massy (France); Marmey, P.; Legeay, G. [CTTM, 20 rue Thalès de Milet 72000 Le Mans (France); Debarnot, D. [Institut des Molécules et Matériaux du Mans (IMMM), département Polymères, Colloïdes et Interfaces, UMR CNRS 6283 Université LUNAM, av. O. Messiaen, 72085 Le Mans (France); Bellon-Fontaine, M.N. [INRA-AgroParisTech, UMR 1319 MICALIS, équipe B2HM, 25 avenue de la République, 91300 Massy (France)

    2013-04-01

    Different polymeric surfaces have been modified in order to reach a high hydrophobic character, indeed the superhydrophobicity property. For this purpose, polypropylene and polystyrene have been treated by RF or μwaves CF{sub 4} plasma with different volumes, the results were compared according to the density of injected power. The effect of pretreatment such as mechanical abrasion or plasma activation was also studied. The modified surfaces were shown as hydrophobic, or even superhydrophobic depending of defects density. They were characterized by measurement of wettability and roughness at different scales, i.e. macroscopic, mesoscopic and atomic. It has been shown that a homogeneous surface at the macroscopic scale could be heterogeneous at lower mesoscopic scale. This was associated with the crystallinity of the material. The bioadhesion tests were performed with Gram positive and negative pathogenic strains: Listeria monocytogenes, Pseudomonas aeruginosa and Hafnia alvei. They have demonstrated an antibacterial efficiency of very hydrophobic and amorphous PS treated for all strains tested and a strain-dependent efficiency with modified PP surface being very heterogeneous at the mesoscopic scale. Thus, these biological results pointed out not only the respective role of the surface chemistry and topography in bacterial adhesion, but also the dependence on the peaks and valley distribution at bacteria dimension scale. Highlights: ► Simple, eco-friendly modification of polymers leading to highly hydrophobic property ► Plasma treatment inducing surface fluorination and roughness ► Study of non-adhesion of different types of bacteria onto such polymeric surfaces ► Dependence of their non-adhesion on surface topography whatever their characteristics.

  8. Flat friction tests applied to austenic stainless steels with several surface finish. Analysis of adhesion conditions in friction

    International Nuclear Information System (INIS)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatatyd, A.; Martinez, A.

    2008-01-01

    The main purpose of this work is to evaluate the tribological behaviour of austenic stainless steels AISI 304 with bright surface finishing (B). The assays have been carried out in flat faced dies system with mineral oil of 200 cts viscosity, S 2 Mo grease and in dry conditions. The relationship between friction coefficient and pressure and velocity has been established for the mineral oil as lubricant. In these conditions, a strong adhesive tendency has been found in boundary lubrication regime. The results obtained here, show us that S 2 Mo grease leads to lowest values for the friction coefficient. A minor adhesive behaviour tendency for AISI 316 steel, harder than 304 grades, has been found. A relevant plowing phenomena has been observed for the more critical friction conditions tried out. A surface hardener is produced as a consequence of that. (Author) 19 refs

  9. Determination of Energy Fluxes Over Agricultural Surfaces

    Directory of Open Access Journals (Sweden)

    Josefina Argete

    1994-12-01

    Full Text Available An energy budget was conducted over two kinds if surfaces: grass and corn canopy. The net radiative flux and the soil heat flux were directly measured while the latent and sensible heat flux were calculated from the vertical profiles if wet and dry-bulb temperature and wind speed. The crop storage flux was also estimated. Using the gradient or aerodynamic equations, the calculated fluxes when compared to the measured fluxes in the context of an energy budget gave an SEE = 63 Wm-2 over grass and SEE = 81 Wm-2 over corn canopy. The calculated fluxes compared reasonably well with those obtained using the Penman equations.For an energy budget research with limited instrumentation, the aerodynamic method performed satisfactorily in estimating the daytime fluxes, when atmospheric conditions are fully convective, but failed when conditions were stably stratified as during nighttime.

  10. Influence of light intensity on surface free energy and dentin bond strength of core build-up resins.

    Science.gov (United States)

    Shimizu, Y; Tsujimoto, A; Furuichi, T; Suzuki, T; Tsubota, K; Miyazaki, M; Platt, J A

    2015-01-01

    We examined the influence of light intensity on surface free energy characteristics and dentin bond strength of dual-cure direct core build-up resin systems. Two commercially available dual-cure direct core build-up resin systems, Clearfil DC Core Automix with Clearfil Bond SE One and UniFil Core EM with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in acrylic resin and the facial dentin surfaces were wet ground on 600-grit silicon carbide paper. Adhesives were applied to dentin surfaces and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm(2). The surface free energy of the adhesives (five samples per group) was determined by measuring the contact angles of three test liquids placed on the cured adhesives. To determine the strength of the dentin bond, the core build-up resin pastes were condensed into the mold on the adhesive-treated dentin surfaces according to the methods described for the surface free energy measurement. The resin pastes were cured with the same light intensities as those used for the adhesives. Ten specimens per group were stored in water maintained at 37°C for 24 hours, after which they were shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. Two-way analysis of variance (ANOVA) and a Tukey-Kramer test were performed, with the significance level set at 0.05. The surface free energies of the adhesive-treated dentin surfaces decreased with an increase in the light intensity of the curing unit. Two-way ANOVA revealed that the type of core build-up system and the light intensity significantly influence the bond strength, although there was no significant interaction between the two factors. The highest bond strengths were achieved when the resin pastes were cured with the strongest light intensity for all the core build-up systems. When polymerized with a light intensity of 200 mW/cm(2) or less, significantly lower bond strengths were observed. CONClUSIONS: The

  11. The neural cell adhesion molecule L1 is distinct from the N-CAM related group of surface antigens BSP-2 and D2

    DEFF Research Database (Denmark)

    Faissner, A; Kruse, J; Goridis, C

    1984-01-01

    The neural cell adhesion molecule L1 and the group of N-CAM related molecules, BSP-2 and D2 antigen, are immunochemically distinct molecular species. The two groups of surface molecules are also functionally distinct entities, since inhibition of Ca2+-independent adhesion among early post-natal m...

  12. The influence of ionic strength on the adhesive bond stiffness of oral streptococci possessing different surface appendages as probed using AFM and QCM-D

    NARCIS (Netherlands)

    Olsson, Adam L. J.; Arun, Narasimhan; Kanger, Johannes S.; Busscher, Henk J.; Ivanov, Ivan E.; Camesano, Terri A.; Chen, Yun; Johannsmann, Diethelm; van der Mei, Henny C.; Sharma, Prashant K.

    2012-01-01

    Bacterial adhesion to surfaces poses threats to human-health, not always associated with adhering organisms, but often with their detachment causing contamination elsewhere. Bacterial adhesion mechanisms may not be valid for their detachment, known to proceed according to a visco-elastic mechanism.

  13. Ceramic Surface Treatment with a Single-component Primer: Resin Adhesion to Glass Ceramics.

    Science.gov (United States)

    Prado, Mayara; Prochnow, Catina; Marchionatti, Ana Maria Estivalete; Baldissara, Paolo; Valandro, Luiz Felipe; Wandscher, Vinicius Felipe

    2018-04-19

    To evaluate the microshear bond strength (μSBS) of composite cement bonded to two machined glass ceramics and its durability, comparing conventional surface conditioning (hydrofluoric acid + silane) to a one-step primer (Monobond Etch & Prime). Machined slices of lithium disilicate ceramic (LDC) (IPS e.max CAD) and feldspathic ceramic (FC) (VITA Mark II) glass ceramics were divided into two groups (n = 10) according to two factors: 1. surface treatment: HF+S (ca 5% hydrofluoric acid [IPS Ceramic Etching GEL] + silane coupling agent [SIL; Monobond Plus]) or MEP (single-component ceramic conditioner; Monobond Etch & Prime); 2. storage condition: baseline (without aging; tested 24 h after cementing) or aged (70 days of water storage + 12,000 thermal cycles). Composite cement (Multilink Automix, Ivoclar Vivadent) was applied to starch matrices on the treated ceramic surfaces and photoactivated. A μSBS test was performed (0.5 mm/min) and the failure pattern was determined. Contact angle and micromorphological analyses were also performed. Data were analyzed with Student's t-test (α = 5%). For both ceramic materials, HF+S resulted in higher mean μSBS (MPa) at baseline (LDC: HF+S 21.2 ± 2.2 > MEP 10.4 ± 2.4; FC: HF+S 19.6 ± 4.3 > MEP 13.5 ± 5.4) and after aging (LDC: HF+S 14.64 ± 2.31 > MEP 9 ± 3.4; FC HF+S: 14.73 ± 3.33 > MEP 11.1 ± 3.3). HF+S resulted in a statistically significant decrease in mean μSBS after aging (p = 0.0001), while MEP yielded no significant reduction. The main failure type was adhesive between composite cement and ceramic. HF+S resuted in the lowest contact angle. Hydrofluoric acid + silane resulted in higher mean μSBS than Monobond Etch & Prime for both ceramics; however, Monobond Etch & Prime had stable bonding after aging.

  14. Constrained Adherable Area of Nanotopographic Surfaces Promotes Cell Migration through the Regulation of Focal Adhesion via Focal Adhesion Kinase/Rac1 Activation.

    Science.gov (United States)

    Lim, Jiwon; Choi, Andrew; Kim, Hyung Woo; Yoon, Hyungjun; Park, Sang Min; Tsai, Chia-Hung Dylan; Kaneko, Makoto; Kim, Dong Sung

    2018-05-02

    Cell migration is crucial in physiological and pathological processes such as embryonic development and wound healing; such migration is strongly guided by the surrounding nanostructured extracellular matrix. Previous studies have extensively studied the cell migration on anisotropic nanotopographic surfaces; however, only a few studies have reported cell migration on isotropic nanotopographic surfaces. We herein, for the first time, propose a novel concept of adherable area on cell migration using isotropic nanopore surfaces with sufficient nanopore depth by adopting a high aspect ratio. As the pore size of the nanopore surface was controlled to 200, 300, and 400 nm in a fixed center-to-center distance of 480 nm, it produced 86, 68, and 36% of adherable area, respectively, on the fabricated surface. A meticulous investigation of the cell migration in response to changes in the constrained adherable area of the nanotopographic surface showed 1.4-, 1.5-, and 1.6-fold increase in migration speeds and a 1.4-, 2-, and 2.5-fold decrease in the number of focal adhesions as the adherable area was decreased to 86, 68, and 36%, respectively. Furthermore, a strong activation of FAK/Rac1 signaling was observed to be involved in the promoted cell migration. These results suggest that the reduced adherable area promotes cell migration through decreasing the FA formation, which in turn upregulates FAK/Rac1 activation. The findings in this study can be utilized to control the cell migration behaviors, which is a powerful tool in the research fields involving cell migration such as promoting wound healing and tissue repair.

  15. High potential of adhesion to biotic and abiotic surfaces by opportunistic Staphylococcus aureus strains isolated from orthodontic appliances.

    Science.gov (United States)

    Merghni, Abderrahmen; Ben Nejma, Mouna; Dallel, Ines; Tobji, Samir; Ben Amor, Adel; Janel, Sébastien; Lafont, Frank; Aouni, Mahjoub; Mastouri, Maha

    2016-02-01

    Orthodontic and other oral appliances act as reservoir of opportunistic pathogens that can easily become resistant to antibiotics and cause systemic infections. The aim of this study was to investigate the ability of Staphylococcus aureus strains isolated from healthy patients with orthodontic appliances, to adhere to biotic (HeLa cells) and abiotic surfaces (polystyrene and dental alloy). Adhesive ability to polystyrene was tested by crystal violet staining and quantitative biofilm production on dental alloy surfaces was evaluated by MTT reduction assay. In addition, the presence of icaA and icaD genes was achieved by polymerase chain reaction (PCR). Qualitative biofilm production revealed that 70.6% of strains were slime producers. The metabolic activity of S. aureus biofilms on dental alloy surfaces was high and did not differ between tested strains. Moreover, all the isolates were adhesive to HeLa cells and 94% of them harbor icaA and icaD genes. Considerable adhesion and internalization capacity to the epithelial HeLa cells and strong biofilm production abilities together, with a high genotypic expression of icaA/icaD genes are an important equipment of S. aureus to colonize orthodontic appliances and eventually to disseminate towards other body areas. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Bond strength of novel CAD/CAM restorative materials to self-adhesive resin cement: the effect of surface treatments.

    Science.gov (United States)

    Elsaka, Shaymaa E

    2014-12-01

    To evaluate the effect of different surface treatments on the microtensile bond strength (μTBS) of novel CAD/CAM restorative materials to self-adhesive resin cement. Two types of CAD/CAM restorative materials (Vita Enamic [VE] and Lava Ultimate [LU]) were used. The specimens were divided into five groups in each test according to the surface treatment performed; Gr 1 (control; no treatment), Gr 2 (sandblasted [SB]), Gr 3 (SB+silane [S]), Gr 4 (hydrofluoric acid [HF]), and Gr 5 (HF+S). A dual-curing self-adhesive resin cement (Bifix SE [BF]) was applied to each group for testing the adhesion after 24 h of storage in distilled water or after 30 days using the μTBS test. Following fracture testing, specimens were examined with a stereomicroscope and SEM. Surface roughness and morphology of the CAD/CAM restorative materials were characterized after treatment. Data were analyzed using ANOVA and Tukey's test. The surface treatment, type of CAD/CAM restorative material, and water storage periods showed a significant effect on the μTBS (p0.05). On the other hand, for the VE/BF system, surface treatment with HF+S showed higher bond strength values compared with SB and HF surface treatments (pmaterials was modified after treatments. The effect of surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement is material dependent. The VE/BF CAD/CAM material provided higher bond strength values compared with the LU/BF CAD/CAM material.

  17. Polymer films with surfaces unmodified and modified by non-thermal plasma as new substrates for cell adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Borges, A.M.G.; Benetoli, L.O. [Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Licínio, M.A. [Department of Clinical Analysis, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Zoldan, V.C. [Department of Physical, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Santos-Silva, M.C. [Department of Clinical Analysis, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Assreuy, J. [Department of Pharmacology, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Pasa, A.A. [Department of Physical, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Debacher, N.A. [Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil); Soldi, V., E-mail: vsoldi@pq.cnpq.br [Department of Chemistry, Federal University of Santa Catarina, 88040-900 Florianopolis (Brazil)

    2013-04-01

    The surface properties of biomaterials, such as wettability, polar group distribution, and topography, play important roles in the behavior of cell adhesion and proliferation. Gaseous plasma discharges are among the most common means to modify the surface of a polymer without affecting its properties. Herein, we describe the surface modification of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films using atmospheric pressure plasma processing through exposure to a dielectric barrier discharge (DBD). After treatment the film surface showed significant changes from hydrophobic to hydrophilic as the water contact angle decreasing from 95° to 37°. All plasma-treated films developed more hydrophilic surfaces compared to untreated films, although the reasons for the change in the surface properties of PS and PMMA differed, that is, the PS showed chemical changes and in the case of PMMA they were topographical. Excellent adhesion and cell proliferation were observed in all films. In vitro studies employing flow cytometry showed that the proliferation of L929 cells was higher in the film formed by a 1:1 mixture of PS/PMMA, which is consistent with the results of a previous study. These findings suggest better adhesion of L929 onto the 1:1 PS/PMMA modified film, indicating that this system is a new candidate biomaterial for tissue engineering. Highlights: ► The PS/PMMA films showed hydrophilic surface after DBD-treatment. ► The 1:1 PS/PMMA modified film is a new substrate for L929 cell proliferation. ► The 1:1 PS/PMMA blend film showed additional 170 × 10{sup 3} cells after treatment. ► The proliferation of cells in the blend film triplicated when compared to control. ► Synergistic effect improves cell proliferation in the blend film.

  18. Evaluation and criterion determination of the low-k thin film adhesion by the surface acoustic waves with cohesive zone model

    Science.gov (United States)

    Xiao, Xia; Qi, Haiyang; Sui, Xiaole; Kikkawa, Takamaro

    2017-03-01

    The cohesive zone model (CZM) is introduced in the surface acoustic wave (SAW) technique to characterize the interfacial adhesion property of the low-k thin film deposited on the Silicon substrate. The ratio of the two parameters in the CZM, the maximum normal traction and normal interface characteristic length, is derived to evaluate the interfacial adhesion properties quantitatively. In this study, the adhesion criterion to judge the adhesion property is newly proposed by the CZM-SAW technique. The criterion determination processes of two kinds of film, dense and porous Black Diamond with different film thicknesses, are presented in this paper. The interfacial adhesion properties of the dense and porous Black Diamond films with different thicknesses are evaluated by the CZM-SAW technique quantitatively and nondestructively. The quantitative adhesion properties are obtained by fitting the experimental dispersion curves with maximum frequency up to 220 MHz with the theoretical ones. Results of the nondestructive CZM-SAW technique and the destructive nanoscratch exhibit the same trend in adhesion properties, which means that the CZM-SAW technique is a promising method for determining the interfacial adhesion. Meanwhile, the adhesion properties of the detected samples are judged by the determined criterion. The test results show that different test film materials with different film thicknesses ranging from 300 nm to 1000 nm are in different adhered conditions. This paper exhibits the advantage of the CZM-SAW technique which can be a universal method to characterize the film adhesion.

  19. RESEARCH OF ADHESIVE STRENGTH OF NEW CONCRETE LAYER WITH A SURFACE OF OLD CONCRETE

    Directory of Open Access Journals (Sweden)

    Bulgakov Boris Igorevich

    2016-04-01

    Full Text Available Concrete is a material very commonly used in modern construction, each year over 4 billion m3 of concrete is used around the world. In the recent years high-quality fine grain and other types of concrete allow giving the modern creation city buildings new architectural expressivity, meeting the requirements of the XXI century. The trend of using of these new types of concrete is also applied in the construction of tunnel systems and the subway. The fine-grained high performance concrete obtained by using a mixture of organo-mineral additives and fiber reinforcement, compares fovourably with ordinary fine-grained concrete, namely its bending and tensile strength is higher, it has good resistance to shock impacts and fatigue, as well as crack resistance, water resistance and resistance to erosion. So this type of fine-grained high performance concrete is suitable for the construction of subway tunnels and other special objects. When evaluating the concrete performance in underground rock layers subjected to complex mechanical forces, it is important to take into account the stress of metro upon departure and stopping at the stations. The article presents a new experimental method of determining the adhesion strength of fine-grained high performance concrete layer freshly poured on the surface of old concrete in the process of construction and repair of underground. The result of this method application showed that fine-grained high performance concrete is capable of skid resistance higher than 55 % compared to regular fine-grained concrete without additives.

  20. Adhesive wafer bonding

    Science.gov (United States)

    Niklaus, F.; Stemme, G.; Lu, J.-Q.; Gutmann, R. J.

    2006-02-01

    Wafer bonding with intermediate polymer adhesives is an important fabrication technique for advanced microelectronic and microelectromechanical systems, such as three-dimensional integrated circuits, advanced packaging, and microfluidics. In adhesive wafer bonding, the polymer adhesive bears the forces involved to hold the surfaces together. The main advantages of adhesive wafer bonding include the insensitivity to surface topography, the low bonding temperatures, the compatibility with standard integrated circuit wafer processing, and the ability to join different types of wafers. Compared to alternative wafer bonding techniques, adhesive wafer bonding is simple, robust, and low cost. This article reviews the state-of-the-art polymer adhesive wafer bonding technologies, materials, and applications.

  1. Adhesion-related glycocalyx study: quantitative approach with imaging-spectrum in the energy filtering transmission electron microscope (EFTEM).

    Science.gov (United States)

    Soler, M; Desplat-Jego, S; Vacher, B; Ponsonnet, L; Fraterno, M; Bongrand, P; Martin, J M; Foa, C

    1998-06-05

    Large polysaccharide molecules composing the glycocalyx have been shown to prevent cell adhesion. However, this process was not observed microscopically. Terbium labeling, combined with a new quantitative imaging method based on electron energy loss spectroscopy, allowed specific glycocalyx staining with excellent contrast. Image analysis enabled us to compare glycocalyx structure in free membrane areas and contacts between monocytic cells and bound erythrocytes. Apparent glycocalyx thickness, in contact areas, was half of the sum of glycocalyx thicknesses in free areas without label density increase. Ultrastructural immunogold localization of CD43 molecules, a major component of glycocalyx, was also demonstrated to be excluded from contact areas during adhesion. Thus, both approaches strongly suggest that some glycocalyx elements must exit from contact to allow binding of adhesion molecules.

  2. Adhesion of nitrile rubber to UV-assisted surface chemical modified PET fabric, part II: Interfacial characterization of MDI grafted PET

    Energy Technology Data Exchange (ETDEWEB)

    Razavizadeh, Mahmoud; Jamshidi, Masoud, E-mail: mjamshidi@iust.ac.ir

    2016-08-30

    Highlights: • In this research UV-irradiated PET fabric was chemically modified. • The fabric at first carboxylated under UV irradiation using glutaric anhydride, then it was grafted using isocyanate (i.e. MDI). • The surface of the fabric was characterized before and after each treating satge. • The composite samples were prepared and tested for T-Peel test. The surfaces of the fabrics were surface characterized to understand. - Abstract: Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.

  3. Facile spray-coating process for the fabrication of tunable adhesive superhydrophobic surfaces with heterogeneous chemical compositions used for selective transportation of microdroplets with different volumes.

    Science.gov (United States)

    Li, Jian; Jing, Zhijiao; Zha, Fei; Yang, Yaoxia; Wang, Qingtao; Lei, Ziqiang

    2014-06-11

    In this paper, tunable adhesive superhydrophobic ZnO surfaces have been fabricated successfully by spraying ZnO nanoparticle (NP) suspensions onto desired substrates. We regulate the spray-coating process by changing the mass percentage of hydrophobic ZnO NPs (which were achieved by modifying hydrophilic ZnO NPs with stearic acid) in the hydrophobic/hydrophilic ZnO NP mixtures to control heterogeneous chemical composition of the ZnO surfaces. Thus, the water adhesion on the same superhydrophobic ZnO surface could be effectively tuned by controlling the surface chemical composition without altering the surface morphology. Compared with the conventional tunable adhesive superhydrophobic surfaces, on which there were only three different water sliding angle values: lower than 10°, 90° (the water droplet is firmly pinned on the surface at any tilted angles), and the value between the two ones, the water adhesion on the superhydrophobic ZnO surfaces has been tuned effectively, on which the sliding angle is controlled from 2 ± 1° to 9 ± 1°, 21 ± 2°, 39 ± 3°, and 90°. Accordingly, the adhesive force can be adjusted from extremely low (∼2.5 μN) to very high (∼111.6 μN). On the basis of the different adhesive forces of the tunable adhesive superhydrophobic surfaces, the selective transportation of microdroplets with different volumes was achieved, which has never been reported before. In addition, we demonstrated a proof of selective transportation of microdroplets with different volumes for application in the droplet-based microreactors via our tunable adhesive superhydrophobic surfaces for the quantitative detection of AgNO3 and NaOH. The results reported herein realize the selective transportation of microdroplets with different volumes and we believe that this method would potentially be used in many important applications, such as selective water droplet transportation, biomolecular quantitative detection and droplet-based biodetection.

  4. Sodium alginate/heparin composites on PVC surfaces inhibit the thrombosis and platelet adhesion: applications in cardiac surgery.

    Science.gov (United States)

    Gao, Wenqing; Lin, Tingting; Li, Tong; Yu, Meili; Hu, Xiaomin; Duan, Dawei

    2013-01-01

    Thrombosis and hemocyte damage are the main problems of applied non-coated biomaterials to cardiac surgery that remain unsolved. The present study is aimed at the chemical modification of polyvinyl chloride (PVC) for applications in cardiac surgery and the biological property assessment of modified PVC. Sodium alginate (SA)/heparin (HEP) composites were covalently immobilized onto the surface of the PVC pipeline. The surface grafting density and protein adsorption were determined by ultraviolet spectrophotometry. The surface contact angles were evaluated by contact-angle measurement, whereas the surface characteristics were evaluated by Fouriertransform infrared spectroscopy. Blood coagulation time and platelet adhesion were measured using an automated blood coagulation analyzer and a hemocytometer, respectively. Surface morphologies of the thrombus and platelets were evaluated by scanning electron microscopy. The immobilization of SA/HEP reduced the contact angles of the coated surface. Protein adsorption was reduced by the immobilization of SA. The activated partial thrombin time and thrombin time of the coated PVC were significantly prolonged as compared with the non-coated PVC. Platelet adhesion and thrombus formation were all reduced by the immobilization of HEP. The results revealed that the SA/HEP coating can improve the antithrombogenicity of the PVC pipeline, as well as improve its biocompatibility and hemocompatibility, which are essential for cardiac pulmonary bypass surgery.

  5. Friction enhancement via micro-patterned wet elastomer adhesives on small intestinal surfaces

    Science.gov (United States)

    Kwon, Jiwoon; Cheung, Eugene; Park, Sukho; Sitti, Metin

    2006-12-01

    A micro-pillar-based silicone rubber adhesive coated with a thin silicone oil layer is investigated in this paper for developing friction-based clamping mechanisms for robotic endoscopic microcapsules. These adhesives are shown to enhance the frictional force between the capsule and the intestinal wall by a factor of about seven over a non-patterned flat elastomer material. In this study, tests performed on fresh samples of pig small intestine are used to optimize the diameter of the micro-pillars to maximize the frictional forces. In addition, the effects of other factors such as the oil viscosity and applied normal forces are investigated. It is demonstrated that the proposed micro-pillar pattern based elastomer adhesive exhibits a maximal frictional force when the pillar diameter is 140 µm and coated silicon oil has a very high viscosity (10 000 cSt). It is also found that the frictional force of the micro-patterned adhesive increases nonlinearly in proportion to the applied normal force. These adhesives would be used as a robust attachment material for developing robotic capsule endoscopes inside intestines with clamping capability.

  6. Elimination of the reactivation process in the adhesion of chlorinated SBS rubber with polychloroprene adhesives

    Directory of Open Access Journals (Sweden)

    2007-04-01

    Full Text Available Chlorination treatment of a thermoplastic styrene-butadiene-styrene rubber (SBS with a 3 wt% solution of trichloroisocyanuric acid (TCI in methyl ethyl ketone (MEK introduces chlorinated and oxidized moieties on the rubber surface which increase its surface energy and produces surface microroughness. Consequently adhesion properties, evaluated by T-peel strength measurements in chlorinated SBS/solvent based-polyurethane adhesive/leather joints, are enhanced. In this study, two solvent-based polychloroprene adhesives (PCP0 and PCP30R have been considered as an alternative to the commonly used solvent-based polyurethane adhesive (PU. A thermoreactive phenolic resin was added to one of the polychloroprene adhesive formulations (PCP30R. This tackifier resin favors chlorination of the adhesive and reinforces the interface between the chlorinated adhesive and the chlorinated rubber surface. Besides, PCP30R adhesive does not need adhesive reactivation and considerable high T-peel strength value (5.7±0.3 kN/m was obtained. Elimination of the reactivation process implies a considerable improvement of the manufacturing process in the footwear industry.

  7. Surface Energy Balance System (SEBS) Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    A Surface Energy Balance System (SEBS) has been installed collocated with each deployed Eddy Correlation Flux Measurement System (ECOR) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site, North Slope of Alaska (NSA) site, first ARM Mobile Facility (AMF1), second ARM Mobile Facility (AMF2), and third ARM Mobile Facility (AMF3) at Oliktok Point (OLI). A SEBS was also deployed with the Tropical Western Pacific (TWP) site, before it was decommissioned. Data from these sites, including the retired TWP, are available in the ARM Data Archive. The SEBS consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes.

  8. Theoretical studies of potential energy surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Harding, L.B. [Argonne National Laboratory, IL (United States)

    1993-12-01

    The goal of this program is to calculate accurate potential energy surfaces (PES) for both reactive and nonreactive systems. To do this the electronic Schrodinger equation must be solved. Our approach to this problem starts with multiconfiguration self-consistent field (MCSCF) reference wavefunctions. These reference wavefunctions are designed to be sufficiently flexible to accurately describe changes in electronic structure over a broad range of geometries. Electron correlation effects are included via multireference, singles and doubles configuration interaction (MRSDCI) calculations. With this approach, the authors are able to provide useful predictions of the energetics for a broad range of systems.

  9. Nanoscale adhesion, friction and wear studies of biomolecules on silane polymer-coated silica and alumina-based surfaces

    Science.gov (United States)

    Bhushan, Bharat; Kwak, Kwang Joo; Gupta, Samit; Lee, Stephen C

    2009-01-01

    Proteins on biomicroelectromechanical systems (BioMEMS) confer specific molecular functionalities. In planar FET sensors (field-effect transistors, a class of devices whose protein-sensing capabilities we demonstrated in physiological buffers), interfacial proteins are analyte receptors, determining sensor molecular recognition specificity. Receptors are bound to the FET through a polymeric interface, and gross disruption of interfaces that removes a large percentage of receptors or inactivates large fractions of them diminishes sensor sensitivity. Sensitivity is also determined by the distance between the bound analyte and the semiconductor. Consequently, differential properties of surface polymers are design parameters for FET sensors. We compare thickness, surface roughness, adhesion, friction and wear properties of silane polymer layers bound to oxides (SiO2 and Al2O3, as on AlGaN HFETs). We compare those properties of the film–substrate pairs after an additional deposition of biotin and streptavidin. Adhesion between protein and device and interfacial friction properties affect FET reliability because these parameters affect wear resistance of interfaces to abrasive insult in vivo. Adhesion/friction determines the extent of stickage between the interface and tissue and interfacial resistance to mechanical damage. We document systematic, consistent differences in thickness and wear resistance of silane films that can be correlated with film chemistry and deposition procedures, providing guidance for rational interfacial design for planar AlGaN HFET sensors. PMID:18986962

  10. EXPERIMENTAL INVESTIGATION OF THE ADHESIVE CONTACT WITH ELASTOMERS: EFFECT OF SURFACE ROUGHNESS

    Directory of Open Access Journals (Sweden)

    Lars Voll

    2015-04-01

    Full Text Available Adhesion between an elastomer and a steel indenter was studied experimentally and described with an analytical model. Cylindrical indenters having different roughness were brought into contact with an elastomer with various normal forces. After a “holding time”, the indenter was pulled with a constant velocity, which was the same in all experiments. We have studied the regime of relatively small initial normal loadings, large holding times and relatively large pulling velocities, so that the adhesive force did not depend on the holding time but did depend on the initially applied normal force and was approximately proportional to the pulling velocity. Under these conditions, we found that the adhesive force is inversely proportional to the roughness and proportional to the normal force. For the theoretical analysis, we used a previously published MDR-based model.

  11. Adhesions of extracellular surface-layer associated proteins in Lactobacillus M5-L and Q8-L.

    Science.gov (United States)

    Zhang, Yingchun; Xiang, Xinling; Lu, Qianhui; Zhang, Lanwei; Ma, Fang; Wang, Linlin

    2016-02-01

    Surface-layer associated proteins (SLAP) that envelop Lactobacillus paracasei ssp. paracasei M5-L and Lactobacillus casei Q8-L cell surfaces are involved in the adherence of these strain to the human intestinal cell line HT-29. To further elucidate some of the properties of these proteins, we assessed the yields and expressions of SLAP under different incubation conditions. An efficient and selective extraction of SLAP was obtained when cells of Lactobacillus were treated with 5 M LiCl at 37°C in aerobic conditions. The SLAP of Lactobacillus M5-L and Q8-L in cell extracts were visualized by SDS-PAGE and identified by Western blotting with sulfo-N-hydroxysuccinimide-biotin-labeled HT-29 cells as adhesion proteins. Atomic force microscopy contact imaging revealed that Lactobacillus strains M5-L and Q8-L normally display a smooth, homogeneous surface, whereas the surfaces of M5-L and Q8-L treated with 5 M LiCl were rough and more heterogeneous. Analysis of adhesion forces revealed that the initial adhesion forces of 1.41 and 1.28 nN obtained for normal Lactobacillus M5-L and Q8-L strains, respectively, decreased to 0.70 and 0.48 nN, respectively, following 5 M LiCl treatment. Finally, the dominant 45-kDa protein bands of Lactobacillus Q8-L and Lactobacillus M5-L were identified as elongation factor Tu and surface antigen, respectively, by liquid chromatography-tandem mass spectrometry. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  12. Adhesive bonding of resin composite to various titanium surfaces using different metal conditioners and a surface modification system

    Directory of Open Access Journals (Sweden)

    Hercules Jorge ALMILHATTI

    2013-12-01

    Full Text Available Objective: This study evaluated the effect of three metal conditioners on the shear bond strength (SBS of a prosthetic composite material to cpTi grade I having three surface treatments. Material and Methods: One hundred sixty eight rivet-shaped specimens (8.0x2.0 mm were cast and subjected to polishing (P or sandblasting with either 50 mm (50SB or 250 mm (250SB Al2O3. The metal conditioners Metal Photo Primer (MPP, Cesead II Opaque Primer (OP, Targis Link (TL, and one surface modification system Siloc (S, were applied to the specimen surfaces, which were covered with four 1-mm thick layers of resin composite. The resin layers were exposed to curing light for 90 s separately. Seven specimens from each experimental group were stored in water at 37ºC for 24 h while the other 7 specimens were subjected to 5,000 thermal cycles consisting of water baths at 4ºC and 60ºC (n=7. All specimens were subjected to SBS test (0.5 mm/min until failure occurred, and further 28 specimens were analyzed using scanning electron microscope (SEM and X-ray energy-dispersive spectroscopy (EDS. Data were analyzed by 3-way ANOVA followed by post-hoc Tukey's test (α=0.05. Results: On 50SB surfaces, OP groups showed higher SBS means than MPP (P<0.05, while no significant difference was found among OP, S, and TL groups. On 250SB surfaces, OP and TL groups exhibited higher SBS than MPP and S (P<0.05. No significant difference in SBS was found between OP and TL groups nor between MPP and S groups. The use of conditioners on 250SB surfaces resulted in higher SBS means than the use of the same products on 50SB surfaces (P<0.05. Conclusion: Sandblasting associated with the use of metal conditioners improves SBS of resin composites to cpTi.

  13. Bond strength of self-adhesive resin cement to base metal alloys having different surface treatments

    Directory of Open Access Journals (Sweden)

    Farhad Shafiei

    2018-01-01

    Conclusion: Based on the results, sandblasting improves the shear bond strength of self-etch and self-adhesive resin cement to base metal alloys. The best results can be achieved with a combination of sandblasting and metal primers. The performance of resin cement depends on to their chemical composition, not to the type of system.

  14. Nondestructive evaluation of surface coating adhesion using model studies and ultrasonic goniometer experiments

    DEFF Research Database (Denmark)

    Hansen, Peder Bent; Jensen, Leif Bjørnø

    1989-01-01

    A general-purpose model for studying the reflection of acoustic plane waves or line-focused beams from a stratified medium is presented. Loss of adhesion between one or more pairs of layers is taken into account by assuming a partial layer tangential-displacement slip between the layers. Measurem...

  15. ADHESION OF LACTOBACILLI TO URINARY CATHETERS AND DIAPERS - EFFECT OF SURFACE-PROPERTIES

    NARCIS (Netherlands)

    REID, G; LAM, D; BRUCE, AW; VANDERMEI, HC; BUSSCHER, HJ