Related Surface Properties Research Articles

Investigation of the Relationship between Surface Features, Protein Adsorption, and Osteoimmunomodulation: The Case of a Chemically Treated Titanium Alloy.

This paper deals with the combined effects of immune response and osseointegration because of the lack of comprehensive studies on this topic. An antibacterial Ti surface was considered because of the high risk of infection for titanium bone implants. A chemically treated Ti6Al4 V alloy [Ti64(Sr-Ag)] with a microporous and Sr-Ag doped surface was compared to a polished version (Ti64) regarding protein adsorption (albumin and fibronectin) and osteoimmunomodulation. Characterization via fluorescence microscopy and zeta potential showed a continuous fibronectin layer on Ti64(Sr-Ag), even with preadsorbed albumin, while it remained filamentous on Ti64. Macrophages (differentiated from THP-1 monocytes) were cultured on both surfaces, with viability and cytokine release analyzed. Differently from Ti64, Ti64(Sr-Ag) promoted early anti-inflammatory responses and significant downregulation of VEGF. Ti64(Sr-Ag) also enhanced human bone marrow mesenchymal cell differentiation toward osteoblasts, when a macrophage-conditioned medium was used, influencing ALP production. Surface properties in relation to protein adsorption and osteoimmunomodulation were discussed.

In Vitro Evaluation of Candida albicans Adhesion and Related Surface Properties of CAD/CAM Denture Base Resins.

The aim of this study was to evaluate the surface roughness, contact angle, and adhesion of Candida albicans to computer-aided designing/computer-aided manufacturing (CAD/CAM) and heat-polymerized (HP) denture base materials. Specimens were allocated to six groups based on the composition of studied denture base materials, HP acrylic resin, milled resins (AvaDent and IvoCad), and 3D-printed resins (ASIGA, FormLabs, and NextDent). Ten specimens per group were used for each test (n = 10/test). Surface roughness and contact angles were analyzed using profilometer and goniometer, respectively. Adhesion of C. albicans was counted using colony-forming unit (CFU/mL). Means and standard deviations were calculated, and then one-way analysis of variance (ANOVA), followed by Tukey's post hoc test. Correlation of Candida adhesion and surface parameters was determined by using Pearson's correlation analysis. No statistically significant difference was noted in surface roughness between HP, milled, and 3D-printed denture base resins except NextDent, which showed significantly higher roughness in comparison to all other resins (p = 0.001). In terms of contact angle, milled resins had the lowest value, followed by HP, ASIGA, and FormLabs, whereas NextDent showed the highest contact angle (p = 0.001). C. albicans adhesion showed no significant difference between all denture base resins. A positive and significant correlation was found between C. albicans adhesion and contact angle (p = 0.003), while no correlation was reported between C. albicans adhesion and surface roughness (p = 0.523). Adhesion of C. albicans was similar in all tested specimens. Surface roughness showed no significant difference between all groups except NextDent, which had the highest value. Milled denture base resins had the lowest contact angle among all groups.

Thermophoresis-Brinkman flow of an aerosol particle within a spherical cavity

A semi-analytical study is presented for the thermophoretic migration of a spherical particle located at an arbitrary position in a porous medium inside a spherical cavity. A uniformly applied temperature gradient parallel to the line connecting the particle and cavity centers. The porous medium is modeled as a Brinkman fluid with a characteristic Darcy permeability K that can be obtained directly from the experimental data. The porous medium is assumed to be homogenous and isotropic, and the solid matrix is in thermal equilibrium with the fluid through the voids of the medium. The Knudsen number is supposed to be small so that the fluid flow through the porous medium can be described by a continuum model with a temperature jump, a thermal creep, a frictional slip, and thermal stress slip at the surface of the aerosol particle. The Reynolds number of the fluid is assumed to be small enough to justify the use of the Brinkman equation, which is always satisfied because the aerosol particle is so small. The Péclet number for heat transfer in thermophoresis is also assumed to be small. The dimensionless thermophoretic velocity and the mobility coefficients are tabulated and represented graphically for various values of the permeability parameter and relative thermal and surface properties of the particle and cavity. Results are in good agreement with the analytical solution of the particular case of a particle located at the center of the cavity.

Surface properties and Streptococcus mutans biofilm adhesion of ion-releasing resin-based composite materials

ObjectiveTo evaluate the adhesion of Streptococcus mutans (S. mutans) and related surface properties of ion-releasing resin-based composite (RBC) restorative materials. MethodsTwo ion-releasing RBCs, Activa (ACT) and Cention-N (CN), were compared to a conventional RBC (Z350) and a resin-modified glass ionomer cement (Fuji-II-LC). Ten disk-shaped specimens were fabricated for each material (n = 40). After standardized surface polishing procedure, the surface properties of the specimens were evaluated using surface roughness measurements by a profilometer and hydrophobicity using water contact angle measurements. To assess bacterial adhesion, the number of S. mutans bacteria was calculated from colony-forming units (CFU). Confocal laser scanning microscope analysis was done for qualitative & quantitative assessment. The data were analyzed using One-way ANOVA followed by Tukey's post-hoc test to compare the mean values of surface roughness, water contact angle and CFU values. To compare the mean dead cell percentage Kruskal-Wallis rank test and Conover test were used. A p-value of ≤ 0.05 was used to report the statistical significance. ResultsZ350 and ACT had the smoothest surfaces, followed by CN, and the roughest surface was seen in FUJI-II-LC. The lowest water contact angles were seen in CN, and Z350, and the highest were in ACT. S. mutans counts were the highest in ACT and the lowest in Z350 and CN. CN and Fuji-II-LC registered the highest percentage of dead bacterial cells, while the lowest were in ACT. SignificanceSurface properties did not significantly influence bacterial adhesion. More S. mutans bacteria accumulated on ACT than on the nanofilled composite and on CN. CN had antibacterial effects against Streptococcus mutans biofilms.

Dynamic water penetration behavior of top coating color and its effects on structure properties of double-coated layer

The relationship between the dynamic water penetration behavior of top coating color and double-coated paper properties, including pore structure, surface roughness, gloss, and surface latex content, was investigated. Top coating was applied onto the precoated paper prepared using different pigment types, thereby having different pore structures. To investigate the effect of dwell time on pore structure and surface latex content, coating speed and the distance between two coating heads of a laboratory coater were adjusted. As the number of pores of the precoated layer increased, the amount of water that penetrated the precoated paper increased, regardless of low shear viscosity of the top coating color. The relative pore ratio and surface properties of the top coated layer were proportional to those of the precoated layer. A UV absorbance analysis was conducted to examine latex binder migration. The latex content on the surface of the coating layer was mainly affected by the dwell time to the dryer after coating.

The Effects of the Temperature and Termination(-O) on the Friction and Adhesion Properties of MXenes Using Molecular Dynamics Simulation.

Two-dimensional transition metal carbides and nitrides (MXenes) are widely applied in the fields of electrochemistry, energy storage, electromagnetism, etc., due to their extremely excellent properties, including mechanical performance, thermal stability, photothermal conversion and abundant surface properties. Usually, the surfaces of the MXenes are terminated by –OH, –F, –O or other functional groups and these functional groups of MXenes are related surface properties and reported to affect the mechanical properties of MXenes. Thus, understanding the effects of surface terminal groups on the properties of MXenes is crucial for device fabrication as well as composite synthesis using MXenes. In this paper, using molecular dynamics (MD) simulation, we study the adhesion and friction properties of Ti2C and Ti2CO2, including the indentation strength, adhesion energy and dynamics of friction. Our indentation fracture simulation reveals that there are many unbroken bonds and large residual stresses due to the oxidation of oxygen atoms on the surface of Ti2CO2. By contrast, the cracks of Ti2C keep clean at all temperatures. In addition, we calculate the elastic constants of Ti2C and Ti2CO2 by the fitting force–displacement curves with elastic plate theory and demonstrate that the elastic module of Ti2CO2 is higher. Although the temperature had a significant effect on the indentation fracture process, it hardly influences maximum adhesion. The adhesion energies of Ti2C and Ti2CO2 were calculated to be 0.3 J/m2 and 0.5 J/m2 according to Maugis–Dugdale theory. In the friction simulation, the stick-slip atomic scale phenomenon is clearly observed. The friction force and roughness (Ra) of Ti2C and Ti2CO2 at different temperatures are analyzed. Our study provides a comprehensive insight into the mechanical behavior of nanoindentation and the surface properties of oxygen functionalized MXenes, and the results are beneficial for the further design of nanodevices and composites.

Does Plasma Treatment Effective for Surface Modification of Polymer? An Overview of Treatment Effect on Adhesive and Tribological Properties

Surface modification with plasma has been widely applied to polymeric materials. This treatment is intended to improve the surface properties of the polymer including its wettability and adhesiveness. The aim of this paper is to provide a review of the literature on the surface treatment of polymers with plasma, which focuses on the effects of adhesive and surface tribology properties. The related surface properties are also reviewed in order to strengthen the review of adhesive properties and tribology. Various types of plasma treatments that have been reviewed reported that plasma can be effectively used to improve surface properties, especially adhesive and tribological properties. On a small surface treatment has been developed plasma jet treatment which has been widely applied in biomedical applications.

Effect of crystallinity and related surface properties on gene expression of primary fibroblasts.

The biomaterial-cells interface is one of the most fundamental issues in tissue regeneration. Despite many years of scientific work, there is no clear answer to what determines the desired adhesion of cells and the synthesis of ECM proteins. Crystallinity is a characteristic of the structure that influences the surface and bulk properties of semicrystalline polymers used in medicine. The crystallinity of polycaprolactone (PCL) was varied by changing the molecular weight of the polymer and the annealing procedure. Measurements of surface free energy showed differences related to substrate crystallinity. Additionally, the water contact angle was determined to characterise surface wettability which was crucial in the analysis of protein absorption. X-ray photoelectron spectroscopy was used to indicate oxygen bonds amount on the surface. Finally, the impact of the crystallinity, and related properties were demonstrated on dermal fibroblasts' response. Cellular proliferation and expression of selected genes: α-SMA, collagen I, TIMP, integrin were analysed.

Research on green dielectric fluids of high-efficient electrical discharge assisted arc milling

Superalloys, titanium alloys, stainless steels, and other difficult-to-cut materials have been widely used in aerospace and military due to their unique physical and chemical properties. Compared with conventional EDM and mechanical milling methods, the electrical discharge assisted arc milling (EDAAM) method can achieve efficient and stable machining when processing these difficult-to-cut materials. The oil-based dielectric fluid, which is often used in conventional EDM, may cause environmental problems if not recycled. In order to improve the environmental performance and study the influence of dielectric fluids, this paper studies the effects of different dielectric fluids on the machining performance of EDAAM. Deionized water and different gases including air, oxygen, nitrogen, and argon were used as the dielectric fluid, graphite was used as tool electrode, and iron-based superalloy A286 (GH2132) was used as the workpiece. Machining performance, including material removal rate, relative electrode wear rate, machining error, and surface properties, including recast layer, surface morphology, and element distribution, were studied. The experimental results show that the combinations of different dielectrics play a vital role in the processing effect. The mixed flushing method of using deionized water and gas medium can ensure the machining efficiency and improve the surface quality of the workpiece.

The secondary electron yields and related surface properties evolution of laser treated stainless steel induced by different ultrasonic cleaning duration

As a novel method, laser treatment was proposed to be applied on the surface modification of stainless steel 316L commonly used in accelerator vacuum system to mitigate the secondary electron emission. However, the final property of the material surfaces, especially the secondary electron yield (SEY) property depends on a rather large number of factors, among them are the surface cleaning scenarios needed before installation. In particular, the surface morphologies and surface chemical states may be changed during the ultrasonic cleaning used for laser treated stainless steel surfaces. Therefore, the influence of ultrasonic cleaning duration on the surface composition, surface morphology and secondary electron characteristics of stainless steel were studied for the first time. The secondary electron yield test results demonstrated that the maximum SEY (δ max) of laser treated stainless steel samples increased with the increase of ultrasonic cleaning time. After ultrasonic cleaning in acetone and absolute ethyl alcohol each for 3 minutes, 10 minutes and 15 minutes, respectively, the δ max of laser treated stainless steel samples increased about 0.7%–1.7%, 1.3%–2.4% and 4.9%–15.3%, respectively, compared with that of uncleaned laser treated ones. The surface morphologies, surface roughness, surface chemical states related to the SEY evolution were also evaluated and analyzed.

Surface adsorption of metallic species onto microplastics with long-term exposure to the natural marine environment.

Microplastics are ubiquitous in most biomes and environments, representing one of the most pressing global environmental challenges. This study investigated the ability of pre-production microplastic pellets to accumulate metals from the marine environment. An accidental ocean discharge of poly(propylene) pellets occurred via a wastewater treatment centre at the coastal city of Warrnambool, Victoria - Australia. These pellets were collected routinely from Shelly Beach, adjacent to the ocean discharge site over a period of 16-months following the spill. This collection formed a unique time-series that accurately represented the degree to which metal ions in the coastal marine environment accumulate on plastic debris. Elemental analysis indicated an increase in concentration over time of rare earth elements and a selection of other metals supporting the hypothesis that microplastics selectively adsorb metals from the environment. A subset of the poly(propylene) pellets contained a surfactant coating which significantly increased the adsorption capacity. The surface properties in relation to adsorption were further explored with surface imaging and these results are also discussed. This study shows how microplastics act as nucleation points and carriers of trace metal ions in marine environments.

Indoor formaldehyde removal by catalytic oxidation, adsorption and nanofibrous membranes: a review

Indoor pollution of air by formaldehyde poses a serious threat to human health because formaldehyde causes illnesses and discomfort even at low levels, thus calling for abatement techniques. Techniques include absorption, physisorption, chemisorption, biological and botanical filtration, photocatalytic decomposition, membrane separation, plasma and catalytic oxidation. Here we review the principles, performances, advantages and disadvantages of these techniques, with focus on catalytic oxidation, adsorption and the use of nanofibrous membranes. Supported noble metal and metal oxide-based materials are efficient catalysts for oxidation. We present photocatalytic oxidation under UV, visible and solar light using composites. Chemisorption method is reviewed with focus on amino-containing adsorbents, conditions of temperature and relative humidity and surface properties. Nanofibrous membranes display high density of active sites for pollutant interactions and allow formaldehyde removal without leaching out of catalyst nanoparticles or adsorbents.

Adhesion of Sphingomonas sp. GY2B onto montmorillonite: A combination study by thermodynamics and the extended DLVO theory

Bacterial adhesion on mineral surface are of fundamental importance in geochemical processes and biogeochemical cycling, such as mineral transformation and clay-mediated biodegradation. In this study, thermodynamics analysis combined with classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory as well as the extended DLVO (XDLVO) theory were employed to investigate the adhesion of the Gram-negative PAH-degrading bacteria Sphingomonas sp. GY2B on montmorillonite (Mt). Scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated the affinity of GY2B for Mt, and the experimental results could be described well by pseudo-second-order (R2 = 0.997) and Langmuir model (R2 = 0.995). The thermodynamics analysis revealed the physical nature of bacterial adhesion onto Mt, which was confirmed by the XDLVO theory. The related surface properties (Zeta potential, hydrodynamic diameter and hydrophobicity) at different ionic strength were determined and the interaction energy between Mt and GY2B were also calculated using the DLVO and XDLVO theories in KCl or CaCl2 solution. At low ionic strength (≤ 20 mM), GY2B adhesion onto Mt was primarily driven by long-range DLVO forces (e.g. electrostatic repulsion), while short-range (separation distance < 5 nm) Van der Waals and hydrophobic interactions played more important roles in the bacterial adhesion at higher ionic strength (50−100 mM). In addition, Mt had a better adhesion capacity to bacteria in Ca2+ solution than that in K+ solution, owing to less negative charge and lower energy barrier in mineral-bacteria system in Ca2+ solution. Overall, the adhesion of bacteria onto Mt could be evaluated well on the basis of the XDLVO theory along with thermodynamics analysis. This study provides valuable insights into the clay-mediated microbial remediation of hydrophobic organic contaminants in the environment.

Surface properties and bacterial adhesion of bulk-fill composite resins

ObjectivesThe aim of the present study was to evaluate the Streptococcus mutans and Streptococcus mitis adhesion and related surface properties of bulk-fill resin composite. MethodsFour novel bulk-fill composite with different composition were used; Sonic Fill-2 (KSF), Filtek BulkFill (FBF), Admira Fusion X-tra (AFX), Beautifil Bulk Restorative (SBB) and a control group (glass) were included in the study. After standardized surface polishing procedure, surface properties of composite specimens were evaluated using surface roughness (SR) measurements by a profilometer, hydrophobicity and surface free energy (SFE) analyses, elemental and topographic analyses by SEM-EDS. To evaluate the bacterial adhesion, composite specimens were immersed in artificial saliva and mucin for pellicle development. After 1-h immersion, bacterial suspension was added to the pellicle-coated specimens, which were incubated at 37 °C in 5% CO2 atmosphere for 24 h. Adhered bacteria counts were determined as x108 Cfu/ml. Bacterial adhesion was also investigated using confocal laser scanning microscopy. ResultsNo statistically significant differences were found among bulk fill composites in terms of surface roughness while glass showed the lowest Ra values. The lowest contact angle values were found in the control group and Sonic Fill-2 while the highest SFE values were observed in these materials. No statistically significant differences were found between the S. mutans counts. For S. Mitis adhesion, the highest value was found in Sonic Fill-2 and no significant differences were observed between the other groups. ConclusionsSR of bulk-fill composite resins had no effect on bacterial adhesion. However, bacterial adhesion increased with higher SFE values. Clinical significanceAlthough the surface roughness of composites used in the study is similar, in clinically, S. mitis adhesion may be more in the KSF group because of high surface free energy.

Effect of nitrogen concentrations on optical, structural and mechanical properties of self organized a-C:N films

Low friction and surface hardness has become an important aspect to study and understand surface engineering of diamond like coating. Investigation of structural and mechanical properties of nitrogenated amorphous Diamond Like Carbon coating has been done. The cross-sectional microstructures, elemental compositions and various phase constituent of the coated layers under different processing conditions have been characterized. Films are deposited in presence of 5%–20% with the increasing rate of 5% and 40% of N2 partial pressure along with Ar gas. 20% N2 pressure shows a critical behavior in Raman spectroscopy and XPS. In this condition the film shows more uniform coating with vertical growth structures as well as brittle behavior. The micro-structural changes on the surface due to migration of N2 and its related surface properties have been examined. AFM studies clearly show that the percentage change in average roughness decreases to 17% as the film thickness increases at 20% N2 incorporation. The positive changes in its mechanical properties have been observed by Nano-indentation techniques. Significance of DLC coating in this condition is clearly seen with the increasing sp3compositions by XPS analysis. All results have been correlated and hence critical range of nitrogen partial pressure has been observed between 20%-23% to give similar sp3 fraction and hence properties that of pure DLC films.

Thermophoretic motion of an aerosol sphere in a spherical cavity

A theoretical investigation of the quasi-steady thermophoresis of an aerosol sphere located arbitrarily in a spherical cavity normal to the line of their centers is presented. In the slip-flow regime for the gas motion, the thermal creep, thermal stress slip, frictional slip, and temperature jump are permitted at the solid surfaces. The general solutions to the conservative equations governing the temperature and fluid velocity distributions in the two spherical coordinate systems with respect to the particle and cavity centers are superimposed, and the boundary conditions are satisfied by a collocation technique. The translational and angular velocities of the particle are determined as functions of the scaled center-to-center distance between the particle and cavity (eccentricity of the particle position), their radius ratio, and their relative thermal and surface properties. The results indicate that the boundary effect on the thermophoretic motion is significant, interesting, and complicated. When the particle is located at the cavity center, its migration velocity agrees well with the available analytical solution. In general, the thermophoretic mobility decreases with increases in the particle-to-cavity size ratio and in the normalized distance between the particle and cavity centers, but there exist some exceptions. The circulating cavity-induced thermoosmotic flow can increase or decrease the thermophoretic migration and retard the particle rotation, even reverse their directions, depending on the geometric and characteristic parameters. The boundary effect on the thermophoretic migration normal to the line through the particle and cavity centers is slightly weaker than that along the line.

Axisymmetric thermophoresis of an aerosol particle in a spherical cavity

The thermophoretic motion of a spherical particle located at an arbitrary position in a gaseous medium inside a spherical cavity is investigated semi-analytically. The temperature gradient is applied along the line connecting the particle and cavity centers. In the slip-flow regime for the gas motion, the temperature jump, frictional slip, thermal creep, and thermal stress slip are permitted at the solid surfaces. The energy and momentum equations are solved using two spherical coordinate frames with respect to the cavity and particle and the boundary conditions at the solid surfaces are satisfied by a collocation method. Results of the thermophoretic velocity are obtained for various values of the relative thermal and surface properties of the particle and cavity, their radius ratio, as well as the normalized distance between their centers (eccentricity of the particle position). In the particular case of the migration of a spherical particle at the center of the cavity, these results agree excellently with the analytical solutions. Interestingly, the contribution to the particle velocity from the thermoosmotic flow at the cavity wall can be equivalent to or even much more important than that from the wall-corrected thermophoretic driving force. The dimensionless thermophoretic velocity of the confined particle decreases significantly with an increase in the normalized distance between the particle and cavity centers or the particle-to-cavity radius ratio. This velocity increases with an increase in the relative thermal conductivity of the solid phases for a specified configuration.

Theory of thermophoresis of a spherical particle embedded in a micropolar fluid

Analytical investigations are considered for the related problems of thermophoresis, photophoresis and thermophoresis with chemical reactions of a spherical aerosol particle embedded in a gaseous micropolar medium. The Knudsen number is assumed to be in the slip-flow regime. Viscous and gyrational dissipations are ignored in the energy equation. At the surface of the particle, a thermal stress slip and the creep slip are considered in the analysis of motion. Expressions for thermophoretic and photophoretic velocities and forces are obtained as functions of the micropolarity parameter characterizing the micropolar medium and the thermal properties of the medium and particle. Results of the effect of the chemical reaction within the particle on its thermophoresis velocity are presented for various distributions of the composition-dependent factor or heat generation parameter of the chemical reaction as well as the relative thermal and surface properties of the aerosol spherical particle. The corresponding limiting cases of the classical viscous fluids are obtained.

Cationic surfactant coating nanodiamonds: Adsorption and peculiarities

Given the unique properties of nanodiamonds, such as biocompatibility, low cytotoxicity and high adsorption capacity, this material is considered to have potential in drug delivery platforms. In this study, we tested nanodiamonds with different surface properties in relation to quaternary ammonium surfactant (Myramistin). For all tested materials that possess positive and negative zeta potential adsorption of surfactants on the surface of nanodiamonds, aggregates in the aqueous suspension are described by the Langmuir adsorption equation.

A study on performance of roller-compacted concrete for pavement

In this study, field test investigation is conducted on roller-compacted concrete pavement (RCCP). A total of five sections of RCCP were constructed in Seokcho of South Korea for this test. Vebe time, a represented parameter of consistency, is employed as quality control parameter for RCC mixture. Performance related properties and surface properties of each section were investigated and correlated to the quality control parameter. Based on the findings from previous researches and results from this field performance investigation, some recommendations for improving mixture design of RCC are suggested.