Untreated Surface Research Articles

Optimization of interfacial bonding properties between thermoplastic liners and carbon fiber‐reinforced composites by atmospheric‐pressure plasma and failure mechanism study

AbstractWeak interfacial bonding properties between thermoplastic liners and carbon fiber‐reinforced composites (CFRP) can easily lead to debonding failure, which is a major challenge in development of type IV composite hydrogen storage vessels. We optimized Box–Behnken design atmospheric‐pressure plasma process parameters for maximizing interfacial bonding properties between thermoplastic liner (PA11 liner) and CFRP using Design‐Expert software. From various designs, plasma process parameters, including time (t), nozzle‐to‐specimen distance (d) and gas flow rate (r) of treatment were selected for optimization to assess the effects of their interactions on climbing drum peel (CDP), flatwise tensile (FWT) and asymmetric double cantilever beams (ADCB). The CDP strength, FWT strength and strain energy release rate (GADCB) of untreated samples were 4.2 N·mm/mm, 0.26 MPa and 87.2 J/m2, respectively. After the plasma treatment, optimum process parameters of t = 200 s, d = 12.5 mm, and r = 700 L/h were used to achieve 33.8 N·mm/mm, 2.97 MPa and 1008.4 J/m2, respectively, which were 8.0, 11.4 and 11.6 times that of untreated PA11 surface, respectively. This method has the potential for guiding thermoplastic liner surface treatment of type IV hydrogen storage vessels before winding.

Surface modification of the Nylon 6,6 and wasted glass fiber‐Nylon 6.6 coatings using atmospheric plasma treatment

AbstractPolymers tend to have low surface free energy, a significant cause of adhesion properties with other substances. Plasma treatment is an optimal method to improve surface properties. This work used a recycled glass fiber‐polymer coating, and another based on Nylon 6,6. The surface modification of both layers was carried out with an atmospheric plasma treatment at different times. Chemical analysis of the plasma treated and the untreated surface were analyzed by infrared spectroscopy and X‐ray diffraction. Atomic force microscopy (AFM) investigated the morphology and topography surface. The plasma treatment results improve wettability and surface free energy. The contact angle decreases for Nylon 6,6 from 68° to 0° and for glass fiber‐polymer from 56° to 18°. However, the wettability remains over time in Nylon 6,6 layer, and the composite material reverts in 15 days. The high surface free energy after plasma treatment was mainly due to an increase in the polar component by inserting polar groups. The % crystallinity increases with plasma treatment due to the loss of the amorphous part of the polymer by plasma etching. AFM analysis shows an improvement in the roughness surface after treatment. These results greatly interest in enhancing adhesion with other substrates.

Mitigation of Salmonella on Food Contact Surfaces by Using Organic Acid Mixtures Containing 2-Hydroxy-4-(methylthio) Butanoic Acid (HMTBa)

Contaminated surfaces can transmit pathogens to food in industrial and domestic food-handling environments. Exposure to pathogens on food contact surfaces may take place via the cross-contamination of pathogens during postprocessing activities. Formaldehyde-based commercial sanitizers in recent years are less commonly being used within food manufacturing facilities due to consumer perception and labeling concerns. There is interest in investigating clean-label, food-safe components for use on food contact surfaces to mitigate contamination from pathogenic bacteria, including Salmonella. In this study, the antimicrobial effects of two types of organic acid mixtures containing 2-hydroxy-4-(methylthio) butanoic acid (HMTBa), Activate DA™ and Activate US WD-MAX™, against Salmonella when applied onto various food contact surfaces were evaluated. The efficacy of Activate DA (HMTBa + fumaric acid + benzoic acid) at 1% and 2% and Activate US WD-MAX (HMTBa + lactic acid + phosphoric acid) at 0.5% and 1% against Salmonella enterica (serovars Enteritidis, Heidelberg, and Typhimurium) were evaluated on six different material surfaces: plastic (bucket elevator and tote bag), rubber (bucket elevator belt and automobile tire), stainless steel, and concrete. There was a significant difference in the Salmonella log reduction on the material surfaces due to the organic acid treatments when compared to the untreated surfaces. The type of material surface also had an effect on the log reductions obtained. Stainless steel and plastic (tote) had the highest Salmonella log reductions (3-3.5 logs), while plastic (bucket elevator) and rubber (tire) had the lowest log reductions (1-1.7 logs) after treatment with Activate US WD-MAX. For Activate DA, the lowest log reductions (~1.6 logs) were observed for plastic (bucket elevator) and rubber (tire), and the highest reductions were observed for plastic (tote), stainless steel, and concrete (2.8-3.2 logs). Overall, the results suggested that Activate DA at 2% and Activate US WD-MAX at 1% are potentially effective at reducing Salmonella counts on food contact surfaces by 1.6-3.5 logs.

Physical, morphological and bioactive properties of Co-Cr-W-Ta alloys: Influence of insertion of tantalum and surface thermochemical treatment on bioactivity.

The development of bioactivity in bioinert metallic alloys is a field of interest aiming to improve some aspects of these materials for implant applications. New Co63 Cr28 W9-x Tax alloys with different Ta concentrations (x=0, 2, 4, 6, and 9% w/w) were synthesized in the work reported here. The alloys were characterized by x-ray diffraction, volumetric density, Vickers microhardness, atomic force microscopy, scanning electron microscopy (SEM), and energy-dispersion x-ray spectroscopy (EDS). Bioactivity properties were evaluated by in vitro tests with simulated body fluid (SBF). In vivo assays were performed to assess biocompatibility. The influence of surface thermochemical treatment and Ta insertion on the bioactive properties of the alloys was investigated. The results showed that the alloy structure comprises εCo and αCo phases, with cobalt as a matrix with Cr, W, and Ta as a solid solution. TaCo2 phase is observed in the alloys with 4, 6, and 9% w/w of Ta, and its amount increase as Ta concentration increases. Volumetric density is reduced (from 8.78 ± 0.06 to 8.56 ± 0.09 g/cm3 ) as Ta concentration increases (from 0% to 9% w/w) mainly due to the lower density of the tantalum compared to the tungsten metal. On the other hand, the TaCo2 phase contributes to the increase of Vickers's hardness by ~17.6% for the alloy with 9% Ta (394.7 ± 8.1HV) compared with Co63 Cr28 W9 (336 ± 5HV). The topographic analysis showed increased roughness and adhesion due to the nucleation of Ta1.1 O1.05 and Ca2 Ta2 O7 crystals after surface thermochemical treatment. The roughness and adhesion increase from 16.9 ± 0.6nm and 8.3 ± 1.8nN (untreated surface) to 255.7 ± 17.7nm and 24.1 ± 12.6nN (treated surface), respectively, for the Co63 Cr28 Ta9 alloy. These results suggest that thermochemical treatment provides surface conditions favorable to hydroxyapatite (HA) nucleation. The SEM and EDS data showed the nucleation of spongy structures, consistent with HA, composed mainly of Ca and P, indicating that oxides tantalum promoted a bioactive response on the sample's surface. The biological assay corroborated the alloy's safety and applicability, highlighting its potential in biomedical application since no harmful effects were observed.

Untreated caries and serum vitamin D levels in children and youth of the United States: NHANES 2013-2014.

This cross-sectional study used data from the National Health and Nutrition Examination Survey (2013-2014). In total, 3,072 participants with ages ranging from 1 to 19 years were included in our sample. The main dependent variable, untreated caries, was defined as having at least one untreated carious surface in any tooth. Serum concentration of 25-hydroxyvitamin D [25(OH)D] was categorized into four groups: ≥75 nmol/ml, 50-74.9 nmol/ml, 25-49.9 nmol/ml, and <25 nmol/ml. Data were analyzed using a binary logistic regression. For children aged 1-5 years, age (OR = 1.68, 95% confidence intervals (95% CI) 1.38-2.04) and low levels of vitamin D (25-49.9 nmol/ml, and <25 nmol/ml: OR = 2.55, 95% CI 1.06-6.13) were associated with untreated caries. For children aged 6-11 years, low levels of vitamin D (50-74.9 nmol/ml: OR=1.45, 95% CI 1.16-1.82) remained associated with untreated caries. No associations were found in those between 12 and 19 years of age. Our findings show an association between low levels of 25(OH)D and untreated caries in children between 1 and 11 years of age, suggesting that this nutrient might interfere in the caries process.

Saturated pool boiling heat transfer enhancement of R245fa based on the surface covered by sintered copper powder with and without nanostructure

The pool boiling characteristics on the enhanced surfaces with sintered copper powder coatings with and without nano-treatment were experimentally investigated. Three kinds of enchanted surfaces formed by sintered porous layers with copper powder particles and their further nano-treated surfaces were adopted as the test surfaces. The thermal oxidation process was used to form nanostructures with super hydrophilic characteristic on the surface of sintered copper particles. Refrigerant R245fa was selected as the test fluid due to the potential the application in electronic cooling field. The saturation temperature of boiling experiments was maintained about 20 °C. The result showed that the boiling heat transfer performance was effectively improved by coating sintered copper powder porous layer on the plain copper surface, and the maximum heat transfer coefficient and CHF value enhancement could reach 151% and 160% of the plain one, respectively. The enhanced surfaces no matter with or without nano-treatment could trigger the nucleation process at the wall superheats lower than 12 °C rather than the value as high as 30 °C for plain copper surface. After nano-treatment, the heat transfer enhancement for sintered porous surfaces was further improved at medium and low heat flux, where the bubble nucleation or detachment remained robust. The CHF peaked as 140% of untreated surface, while the heat transfer coefficient increased to 108% at most.

High-efficient laser-based bionic surface structuring for enhanced surface functionalization and self-cleaning effect

In this work, a laser-based surface functionalization method combining laser surface texturing and silicone oil-assisted heat treatment was developed to fabricate superhydrophobic surface. Two bionic surface patterns, i.e., duck feather pattern and shark skin pattern were designed and fabricated using different laser processing parameters. 3-D digital microscope, scanning electron microscope, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were utilized to analyze the surface morphology and chemistry of the laser functionalized surface. Self-cleaning test was conducted to compare the dust removal ability between the untreated surface and laser functionalized surface. The rough hierarchical surface structure was induced by laser texturing process, and the heat treatment process with silicone oil led to the formation of low surface energy. With the combined effects of surface structure and chemistry, the fabricated surface exhibits superior superhydrophobicity. Moreover, the laser functionalized superhydrophobic surface exhibits good self-cleaning ability, and highly efficient dust removal process was observed owing to the bouncing removal of water droplets. This work is not only simple and convenient, but also significantly reduces the production cost and enhances time efficiency for fabrication of superhydrophobic surface, and thus shows strong potential for applications in diverse areas.

Correction factors to biaxial bending strength of thin silicon die in the ball-on-ring test by considering geometric nonlinearity and material anisotropy

Abstract The ball-on-ring test (BoR) is one of the standard tests for biaxial bending, suggested in ASTM F394-78. This test has been applied to determine the biaxial bending strength of silicon dies to avoid the die edge effect of the three-point bending tests. However, from the literature, when the relatively thin silicon dies are tested, this test suffers from a contact-nonlinearity effect, due to a maximum applied stress moving away from the loading pin center before the specimen failure, and thus results in overestimated maximum stress calculated by the theoretical linear solution. This study aims to investigate this mechanical issue experimentally, theoretically and numerically by taking into account the specimen material anisotropy and thickness effects on the maximum stresses and deflections, and then propose new correction factor equations to the theoretical linear solutions, based on the numerical fitting results of the geometric nonlinear finite element solutions. Those correction factor equations proposed in this study are material-property independent, but specimen thickness dependent, which can be estimated by an interpolation function. It has been proved that the BoR test using the conventional theory associated with the proposed correction factor equations can successfully determine the bending strength of the thin silicon dies on untreated surfaces, which mostly fails in the contact-nonlinear region.

Effect of Hydrogen Peroxide on the Surface and Attractiveness of Various Zirconia Implant Materials on Human Osteoblasts: An In Vitro Study.

The aim of this in vitro study was to investigate the effect of hydrogen peroxide (H2O2) on the surface properties of various zirconia-based dental implant materials and the response of human alveolar bone osteoblasts. For this purpose, discs of two zirconia-based materials with smooth and roughened surfaces were immersed in 20% H2O2 for two hours. Scanning electron and atomic force microscopy showed no topographic changes after H2O2-treatment. Contact angle measurements (1), X-ray photoelectron spectroscopy (2) and X-ray diffraction (3) indicated that H2O2-treated surfaces (1) increased in hydrophilicity (p < 0.05) and (2) on three surfaces the carbon content decreased (33-60%), while (3) the monoclinic phase increased on all surfaces. Immunofluorescence analysis of the cell area and DNA-quantification and alkaline phosphatase activity revealed no effect of H2O2-treatment on cell behavior. Proliferation activity was significantly higher on three of the four untreated surfaces, especially on the smooth surfaces (p < 0.05). Within the limitations of this study, it can be concluded that exposure of zirconia surfaces to 20% H2O2 for 2 h increases the wettability of the surfaces, but also seems to increase the monoclinic phase, especially on roughened surfaces, which can be considered detrimental to material stability. Moreover, the H2O2-treatment has no influence on osteoblast behavior.

Low-pressure plasma treated polycarbonate and polymethyl methacrylate (PMMA) sheets with different surface patterns to change their surface properties

Low-pressure plasmas of carbon tetrafluoride (CF4), oxygen (O2), and air were used to treat the surfaces of polycarbonate (PC) and polymethyl methacrylate (PMMA) to achieve a variety of surface attributes, such as hydrophilicity, hydrophobicity, and surface free energy. Patterns of straight line, triangular and square shapes with different sizes e.g., 0.5 mm, 0.75 mm, and 1 mm dimensions as templates were constructed from stainless-steel sheets with a thickness of 1 mm, via laser cutter, were used to induce the corresponding shape of the functionality on PC and PMMA surfaces during plasma gas treatment were also investigated. The untreated PC and PMMA surfaces have a contact angle (θ) value of 70°±0.47° and 77°±0.80°, respectively. As expected upon CF4 plasma treatment, their contact angle values were increased to 109.04°±0.35° and 105.76°±0.61°, respectively; whereas the air plasma treated surfaces became more hydrophilic with the contact angle values of 29.34°±0.14° and 43.99°±0.22°, correspondingly. Moreover, O2 plasma treated surfaces became more hydrophilic with the contact angle values of 25.32°±0.77° for PC and 39.94°±2.05° for PMMA. Also, surface free energy (SFE) values were decreased to 11±0.87 mN/m from 41.16±0.42 mN/m for PC and to 12.11±1.53 mN/m from 35.93±1.12 mN/m for PMMA upon CF4 treated surfaces. Furthermore, SFE values were increased to 57.59±1.12 and 62.13±1.15 mN/m for PC and PMMA after air plasma treatment. PC surface's, advancing and receding contact angles were determined as 101.48°±0.33° and 65.60°±0.11° respectively for 34.77°±0.50° slide-off angles. Moreover, the advancing and receding contact angles for PMMA were found as 93°±0.64° and 61.60°±1.19°, respectively with a sliding angle of 24.49°±1.14°. X-ray Photoelectron Spectroscopy (XPS) analysis results confirmed the fluorination and oxidation of both PC and PMMA after CF4 and O2 plasma treatments, individually. PC and PMMA surfaces were treated multiple times with CF4 and Air, Air and CF4, O2 and CF4, and CF4 and O2 plasmas in succession. After multiple treatment, PC and PMMA surfaces contact angle values were decreased as low as 10.62°±0.88° and 14.96°±0.2°, respectively.

Atomic-Scale Surface Engineering for Giant Thermal Transport Enhancement Across 2D/3D van der Waals Interfaces.

Heat dissipation in two-dimensional (2D) material-based electronic devices is a critical issue for their applications. The bottleneck for this thermal issue is inefficient for heat removal across the van der Waals (vdW) interface between the 2D material and its supporting three-dimensional (3D) substrate. In this work, we demonstrate that an atomic-scale thin amorphous layer atop the substrate surface can remarkably enhance the interfacial thermal conductance (ITC) of the 2D-MoS2/3D-GaN vdW interface by a factor of 4 compared to that of the untreated crystalline substrate surface. Meanwhile, the ITC can be broadly manipulated through adjusting substrate surface roughness. Phonon dynamic and heat flux spectrum analyses show that this giant enhancement is attributed to the increased phonon densities and channels at the interfaces and enhanced phonon coupling. The slight surface fluctuation in MoS2 and the increased diffuse interfacial scattering facilitate energy transfer from MoS2's in-plane phonons to its out-of-plane phonons and then to the substrate. In addition, it is further found that the substrate and its surface topology can dramatically influence the thermal conductivity of MoS2 due to the reduction of phonon relaxation time, especially for low-frequency acoustic phonons. This study elucidates the effects of the amorphous surface of the substrate on thermal transport across 2D/3D vdW interfaces and provides a new dimension to aid in the heat dissipation of 2D-based electronic devices via atomic-scale surface engineering.

Effect of Temporary Cement, Surface Pretreatment and Tooth Area on the Bond Strength of Adhesively Cemented Ceramic Overlays—An In Vitro Study

Several viewpoints have been reported regarding the effect of temporary cements, different surface pretreatment protocols before adhesive cementation, and predictive factors. This in vitro study tested if temporary cement, pretreatment of the tooth surface, the size of enamel or dentine influence adhesive cementation to zirconia ceramics. Twenty premolars were prepared for determination of enamel and dentin area, bond strength test and failure analysis. The samples were divided into two groups: untreated prior adhesive cementation (n = 10) and with temporary cementation done, pretreated prior adhesive cementation (n = 10). Zirconia overlays (Katana Zirconia STML) were cemented on the grounded flat teeth surfaces using Panavia V5. An additional six premolars underwent dentine tubule analysis with SEM to detect temporary cement residues after temporary cementation on an untreated tooth surface (n = 3) and on a pretreated surface (n = 3). The independent sample t-test was used to compare the two groups and the means of the total tooth, dentin or enamel areas did not differ significantly between the untreated and pretreated specimens. The mean tensile bond strength was significantly (p = 0.005) higher in the pretreated specimens (337N) than in the untreated ones (204N). The overall multivariable linear regression model with three predictors (surface pre-treatment, enamel area and dentine area) was significant (p = 0.003), among which the size of enamel was the strongest predictor (β = 0.506; p = 0.049), followed by the pretreatment effect (β = 0.478; p = 0.001) and the size of dentin area (β = -0.105; p = 0.022).

DEPOSITION OF HYDROPHOBIC FLUOROPOLYMER COATINGS ON A PLASMA-TREATED STAINLESS STEEL SURFACE

A stainless steel surface was treated with a glow discharge plasma. As a result of surface treatment, micro- and nanostructures were obtained. The surface roughness of the samples was increased. Thin fluoropolymer coatings were deposited on treated and untreated surfaces using the hot wire chemical vapor deposition (HWCVD) method. The structure of the obtained samples was studied by scanning and atomic force microscopy. Wetting properties were measured for all samples obtained. It has been shown that pretreatment of the surface before the deposition of fluoropolymer coatings makes it possible to increase the hydrophobicity of the final surfaces. Tests of coatings carried out using an ultrasonic cleaner have shown that plasma pretreatment before deposition and subsequent annealing after deposition make it possible to obtain stable coatings with stable hydrophobic properties.

Investigation of the interfacial bonding effect on self-sensing cementitious coatings for infrastructure monitoring

In the field of structural health monitoring, self-sensing cementitious binders have gained great attention over the past decades due to their high sensing performance and durability. In particular, self-sensing cementitious coatings have seen increased interest due to their high compatibility with concrete structures and their ability to monitor existing infrastructure while using low amounts of material and at lower costs. Geopolymer coatings display favorable characteristics for this application due to their innate electrical properties and high bond strength with concrete structures. Despite the research that has been carried out on self-sensing coatings, the effect of the interfacial bond between the coating and substrate on the coating’s sensing performance has not been investigated. Poor bonding between the two materials can lead to low-quality sensing measurements and data misinterpretation. In this paper, we aim to investigate the bonding effect on the sensing performance of self-sensing geopolymer coatings. For this study fly ash-metakaolin geopolymer coatings were applied onto concrete substrates; the concrete surfaces were treated by employing three different surface preparation methods: mechanical brooming, chemical treatment and the untreated cast surface. The bond strength for each preparation technique was measured with the splitting tensile bond test and the sensing response for the geopolymer coatings under repeated loading was also characterized. Through proper understanding of the interface between cementitious materials, sensing coatings can be tailored accordingly to achieve high sensing performance and thus allowing high-quality monitoring and proactive maintenance in civil infrastructure.

Surface treatment of PTAA hole transport layer for inverted perovskite solar cells

Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) was chosen as a hole transport layer for inverted perovskite solar cells (PSCs). It is the first layer deposited on the FTO substrate and thus directly affect the structure and performance of the PSCs. It was found that untreated PTAA surfaces yielded large distribution of photovoltaic parameters and low reproducibility. In this work, the PTAA powder was dissolved in chlorobenzene (CB) and spin-coated on the FTO substrates and baked at 105 °C for 10 mins as pristine samples. The surface treatment of PTAA was performed by washing the pristine samples with 200 µl dimethyl formamide (DMF) on a spin coater and followed by dynamic spin of 50-75 µl of CB or Toluene (TO). It was observed that the surface treatment affected the wettability of PTAA surface by the reduction of contact angle from 46° of pristine sample to 25° – 35° of treated samples that could lead to a better interface and formation of a MAPbI3 perovskite layer. On the contrary, the optical transmittance and surface morphology the treated samples were insignificantly affected. It was demonstrated that the surface treatment of PTAA using DMF and 50 µl of TO could significantly reduce the fluctuation of photovoltaic parameters and also improve the repeatability of the fabrication process. The maximum power conversion efficiency (PCE) of 15.4% was obtained for the optimal condition.

Long-lasting ceria-based anti-frosting surfaces

Suppressing condensation frosting using superhydrophobic surfaces can have a substantial impact on improving efficiency and safety in many industrial applications. However, the low surface energy coatings on such surfaces can be easily damaged during various harsh operations, which has limited the application potential of passive anti-frosting approaches. Here, we propose robust ceria-based anti-frosting surfaces, where superhydrophobicity is induced by not surface coating but adsorbed hydrocarbon. We also demonstrate how the incorporation of a hydrocarbon source as a binder to the ceria-based coating allows for the quick recovery of superhydrophobicity. In comparison to untreated aluminum surfaces, the developed coatings decreased the frost propagation speed and the ice adhesion strength by 60% and 89%, respectively. The coatings could maintain a low contact angle hysteresis even after 200 cycles of frosting/de-frosting robustness tests and 15,000 cycles of acidity/salinity exposure tests. Using a scalable one-step dipping process, the created coating was incorporated to a fin-tube type heat exchanger, and provided 210% enhanced heat transfer rate and 60% decreased pressure drop. The coatings also provided substantially improved robustness compared to the silane-treated superhydrophobic coating. These findings suggest that the developed ceria-based coatings can be helpful in creating scalable and resilient anti-frosting surfaces for real-world applications.

The Effect of Surface Treatment on the Antibacterial Properties of Wood and the Possibility to Detect the Antibacteriality with Fluorescence Method

Wood is a widely used indoor material, and thus it is important to consider wood performance in microbial cross contamination via surfaces. In this study, both untreated and surface- treated wood materials were studied by simulating airborne bacterial contamination and evaluating the number of bacterial colonies on the material surfaces. The materials studied were untreated pine heartwood and sapwood, spruce, silver birch, and glass as a reference. The intensity of UV-excited fluorescence was measured to find the most antibacterial Scots pine heartwood. The coatings used were varnish and wax for Scots pine sapwood. The surface roughness of all material types was compared, and it was found to be uniform. All untreated wood surfaces had less viable bacterial colonies at all time points compared to the glass reference, and the surface treated samples did not differ from the glass reference indicating that the antibacterial properties of wood were blocked by both varnish and wax. The fluorescence method was practical to use, but wider testing will be needed to validate it more thoroughly. The results indicate also that silver birch has similar antibacterial properties as pine and spruce and hence should be studied further.

Surface modification of silicate, borosilicate, and phosphate bioactive glasses to improve/control protein adsorption: PART II

Bioactive glasses (BGs) are characterized by high biocompatibility and bioactivity and are particularly promising for bone tissue regeneration. Once implanted, the BGs interact with the environment and adsorb chemical moieties and biomolecules. Proteins in body fluids are critical for the success of implants, because the adsorption of specific proteins can either promote or inhibit the adhesion of surrounding tissue or other factors such as bacteria. Controlling protein adsorption by tailoring the surface properties of implanted biomaterials is fundamental. This can determine the fate of the implant. In the current study, four BG compositions (two silicates, one borosilicate, and one phosphate glass) and three model proteins (fibronectin, chimeric avidin, and streptavidin) were considered. Each BG was surface pretreated, and the adsorption of fluorescently labeled fibronectin, chimeric avidin, or streptavidin was monitored. Untreated surfaces were used as controls. The amount and spatial distribution of each protein were estimated by confocal microscopy in fluorescence modality, followed by protein clustering analysis. Although streptavidin was not adsorbed efficiently on any of the considered substrates, BGs were successfully coated with fibronectin and chimeric avidin. Both proteins showed different affinities and surface distributions as functions of the implemented pretreatment on each substrate.

Fabrication of Antibacterial TiO2 Nanostructured Surfaces Using the Hydrothermal Method.

Implant-associated infections (IAI) are a common cause for implant failure, increased medical costs, and critical for patient healthcare. Infections are a result of bacterial colonization, which leads to biofilm formation on the implant surface. Nanostructured surfaces have been shown to have the potential to inhibit bacterial adhesion mainly due to antibacterial efficacy of their unique surface nanotopography. The change in topography affects the physicochemical properties of their surface such as surface chemistry, morphology, wettability, surface charge, and even electric field which influences the biological response. In this study, a conventional and cost-effective hydrothermal method was used to fabricate nanoscale protrusions of various dimensions on the surface of Ti, Ti6Al4V, and NiTi materials, commonly used in biomedical applications. The morphology, surface chemistry, and wettability were analyzed using scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and water contact angle analysis. The antibacterial efficacy of the synthesized nanostructures was analyzed by the use of Escherichia coli bacterial strain. XPS analysis revealed that the concentration of oxygen and titanium increased on Ti and Ti6Al4V, which indicates that TiO2 is formed on the surface. The concentration of oxygen and titanium however decreased on the NiTi surface after hydrothermal treatment, and also a small amount of Ni was detected. SEM analysis showed that by hydrothermal treatment alterations in the surface topography of the TiO2 layer could be achieved. The oxide layer on the NiTi prepared by the hydrothermal method contains a low amount of Ni (2.8 atom %), which is especially important for implantable materials. The results revealed that nanostructured surfaces significantly reduced bacterial adhesion on the Ti, Ti6Al4V, and NiTi surface compared to the untreated surfaces used as a control. Furthermore, two sterilization techniques were also studied to evaluate the stability of the nanostructure and its influence on the antibacterial activity. Sterilization with UV light seems to more efficiently inhibit bacterial growth on the hydrothermally modified Ti6Al4V surface, which was further reduced for hydrothermally treated Ti and NiTi. The developed nanostructured surfaces of Ti and its alloys can pave a way for the fabrication of antibacterial surfaces that reduce the likelihood of IAI.

Development of a water-based functional additive by using isobornyl acrylate copolymer to improve ink-adhesion on untreated polypropylene surfaces: A comparative approach

The good barrier and hot-fill properties of polypropylene (PP) films and sheets make packaging industries advantageous. However, printing over a PP substrate is a major issue encountered in the packaging industry. The present study intends to prepare, characterise, and compare isobornyl acrylate (IBOA)-co-acrylic acid (AA) and isobornyl acrylate (IBOA)-co-methacrylic acid (MAA) based non-halogenated functional additives by using oil in water emulsion processes. The bornyl group of IBOA helps in enhancing molecular bonding with the polypropylene (PP) surface. The various properties of these synthesised functional additives were characterised using dynamic light scattering-particle size and zeta potential analysis, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal gravimetric analysis (TGA), and gel permeation chromatography (GPC). The adhesion of these functional additive incorporated ink samples on different untreated PP surfaces was compared using the cross-cut adhesion test. The methacrylic acid based functional additive shows better adhesion properties as compared to acrylic acid.