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Silicon micropores, Z-pinch, Wire arrays, Plasma-surface interaction, Surface treatment, Silicon wrinkles, Physics, and QC1-999

A novel application for conical wire array Z-pinches to surface science is presented. The axial outflows emitted by a tungsten conical wire array in the form of both a dense plasma jet and energetic ions are used to produce morphological modification of substrate surfaces without using any kind of chemical treatment. In particular, surface modifications of (100) oriented Si substrates in the form of micropores and stripes-like formations after a single interaction of the Si to the axial outflows are obtained. It is found that the prevalence of each kind of formation, either micropores or stripes, on the treated substrate depends on the relative position of the target with respect to the wire array. The results indicate that at distances of 11 cm over the array there is still effect of the dense plasma jet outflow since both micropores and stripes are found. On the contrary, solely stripe-like patterns are found at greater distances where the effect of the dense plasma outflow is minimal or null, and only the ion outflow irradiates the surface. The description of the method and future perspectives of this novel application of surface treatment are shown and discussed.

adhesion, plasma, low-pressure plasma, surface treatment, dental ceramics, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

The introduction of new ceramic materials for dental restorations is currently a reality; however, little information is available on their surface treatment for the bonding process. Furthermore, surface treatment with plasma on ceramic materials has been recently introduced, although not many studies are available. The aim of this study was to evaluate the surface properties of a leucite-reinforced feldspar ceramic (LIC) and resin matrix ceramic (RMC) after low-pressure plasma treatment. From each material, 48 discs were prepared and subject to surface treatment. The LIC group was treated by hydrofluoric acid (HF) (LIC-HF), plasma with oxygen (LIC-O2), and plasma with argon (LIC-Ar). The RMC group was treated by sandblasting with alumina (RMC-SB), plasma with oxygen (RMC-O2), and plasma with argon (RMC-Ar). The groups whose surfaces were not subjected to treatment were considered as the control group. Surface wettability and roughness was analyzed. The results showed significant differences among the treatments for both ceramics regarding wettability and roughness. Plasma treatments increased the wettability and had a very low effect on the roughness. Plasma treatments achieved similar values for both surface properties in each ceramic group with no differences between both treatments. Plasma treatment seems to be a promising alternative for ceramic surface treatments since it increased the surface energy of the ceramics analyzed and hardly affects the roughness. Further studies are necessary to evaluate the effect of plasma treatment on the bond strength of ceramics.

volatile organic compounds, surface treatment, surface plasmon resonance, thin film measurement, XPS, dropwise condensation, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

Using surface plasmon resonance imaging (SPRi), we have recently shown for the first time the existence of a monolayer water film between droplets during dropwise condensation. This study examines the effect of adsorbed volatile organic compounds (VOCs) on the ultrathin film measurement using SPRi. Further, the work presents the proper surface-treatment process that enables measurements of the ultrathin water layer during high-speed imaging of dropwise condensation at 3000 frame per second. In this study, two methods were applied for cleaning the surface (gold-coated glass)—(1) standard cleaning procedure (SCP) using acetone, isopropyl alcohol, and deionized water and (2) SCP followed by air plasma cleaning. This work discusses the effect of the cleaning procedures on surface roughness, contact angle, and surface chemistry using atomic force microscopy, optical microscopy, and an X-ray photoelectron spectroscope meter. The results showed that SCP before the SPRi is a proper surface-treatment method. The effect of adsorbed VOCs during dropwise condensation on a surface treated with SCP was measured to be 0.0025 (reflectivity unit), which was 70% smaller than the reflectance associated with a monolayer water film. The results of this work confirm a monolayer water film observation during the dropwise condensation, which has been reported before.

surface treatment, series resistance, current transfer mechanisms, molybdenum oxide, silicon, Physics, and QC1-999

The paper presents the results of studies of the effect of silicon surface treatment on the electrical and photoelectric properties of nanostructured MoOx/n-Si heterojunctions. The nanostructured heterojunctions MoOx/n-Si, were prepared by deposition of thin films of molybdenum oxide (n-type conductivity) by reactive magnetron sputtering in the universal vacuum system Leybold Heraeus L560 on the nanostructured silicon substrates (n-type conductivity), which were made by chemical etching with the assistance of silver nanoparticles. Dark and light volt-ampere (I – V) characteristics of the heterojunctions under study were measured, the value of the potential barrier height, the values of the serial Rs and the shunt Rsh resistance at room temperature were determined. It was established that the silicon surface treatment does not affect the potential barrier height, but significantly affects the values of serial Rs and shunt Rsh resistance. The electrical and photoelectric properties of the obtained structures were investigated, the dominant mechanisms of current transfer through the heterostructures under forward bias are well described in the framework of emission-recombination and tunneling models with the presence of interface states. The main mechanism for the charge carrier transport through heterojunctions with the reverse bias is the Frenkel–Pool emission. Investigation of photoelectric properties of heterojunctions MoOx/n-Si was carried out at illumination by white light with intensity Popt = 80 mW/сm2. It was established that the heterostructure No.5 MoOx/n-Si with grown nanowires and etched silver nanoparticles has a maximum open-circuit voltage Voc = 0.17 V, short-circuit current density Isc = 10 mA/cm2. The possibilities of using the obtained heterostructures as photodiodes were analyzed.

surface treatment, cementitious spacer, chloride resistance, concrete, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

Spacers are important components in reinforced concrete structures to provide cover between the steel reinforcement and the formwork. Cementitious spacers are of particular interest for coastal engineering structures, as they are compatible with cement-based chloride-resistant high-performance concrete compared to plastic and steel spacers. However, the cementitious spacer–concrete interface was found to be highly porous and microcracked. This study investigated the effect of surface treatment on the chloride ion transport at the cementitious spacer–concrete interface. A surface treatment technique for potential mass production was introduced and the state-of-practice tests of the hardened concrete were modified to evaluate the performance of the spacer–concrete composite specimens. The results showed that the surface treatment on a cementitious spacer improved the bonding between the spacer and concrete at the interface. The surface treatment of the spacer improved the compressive strength and the chloride resistance of the composite specimen locally compared to those without surface treatment. The advantage of surface treatment on the chloride resistance was partially represented in either the diffusion coefficient or the column electric flux. The maximum chloride ion penetration depth at the spacer–concrete interface was recommended as an additional proxy for the evaluation of the chloride resistance performance of composite specimens.

GFRP composite structures, slip-critical connection, stainless-steel cover plates, surface treatment, prevailing torque, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

Composite structures have become increasingly popular in civil engineering due to many advantages, such as light weight, excellent corrosion resistance and high productivity. However, they still lack the strength, stiffness, and convenience of constructions of fastener connections in steel structures. The most popular fastener connections in steel structures are slip-critical connections, and the major factors that influence their strength are the slip factors between faying surfaces and the clamping force due to the prevailing torque. This paper therefore examined the effect that changing the following parameters had on the slip factor: (1) replacing glass fiber reinforced plastic (GFRP) cover plates with stainless-steel cover plates; (2) adopting different surface treatments for GFRP-connecting plates and stainless-steel cover plates, respectively; and (3) applying different prevailing torques to the high-strength bolts. The impact on the long-term effects of the creep property in composite elements under the pressure of high-strength bolts was also studied with pre-tension force relaxation tests. It is shown that a high-efficiency fastener connection can be obtained by using stainless-steel cover plates with a grit-blasting surface treatment, with the maximum slip factor reaching 0.45, while the effects of the creep property are negligible.

surface roughness, microhybrid composite, sandblasting, surface treatment, composite repair, minimal invasive dentistry, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

Background: Repairing a restoration is a more advantageous and less invasive alternative to its total makeover. The aim of this study was to analyze the effects of chemical and mechanical surface treatments aimed at increasing the roughness of a supra-nano composite resin. Methods: 27 cylindrical blocks of microhybrid composite were made. The samples were randomly divided into nine groups (n = 3). The samples’ surface was treated differently per each group: acid etching (35% H3PO4, 30 s and 60 s), diamond bur milling, sandblasting and the combination of mechanical treatment and acid etching. The samples’ surface was observed by a scanning electron microscope (SEM) and a confocal microscope for observational study, and surface roughness (Ra) was recorded for quantitative analysis. Results: The images of the samples sandblasted with Al2O3 showed the greatest irregularity and the highest number of microcavities. The surfaces roughened by diamond bur showed evident parallel streaks and sporadic superficial microcavities. No significant roughness differences were recorded between other groups. The difference in roughness between the control group, diamond bur milled group and sandblasted group was statistically significant. (p < 0.01). Comparison between the diamond bur milled group and the sandblasted group was also significant (p < 0.01). Conclusion: According to our results, sandblasting is the best treatment to increase the surface roughness of a supra-nano composite.

Plasma-liquid interaction, sunlight degradation, Au/TiO2 nanocomposite, surface treatment, noble metal based photocatalyst, Technology, Engineering (General). Civil engineering (General), TA1-2040, Biology (General), QH301-705.5, Physics, QC1-999, Chemistry, and QD1-999

To enhance the effectiveness of TiO2 as a photocatalyst, it was believed that the drawbacks of the large bandgap and the rapid electron-hole recombination can be overcome by coupling TiO2 with plasmonic metal nanoparticles. The incorporation of the nanoparticles onto the TiO2 surface requires a suitable procedure to achieve the proper particle adhesion. In this work, we propose a simple, clean, and effective surface activation of TiO2 using plasma enhanced wet chemical surface treatment. Under only 5 minutes of plasma treatment in a 3% NH3/3% H2O2 solution, gold nanoparticles were found better adhered onto the TiO2 surface. Hence, the methylene blue degradation rate of the Au/TiO2 under sunlight treated was improved by a factor of 3.25 times in comparison to non-treated Au/TiO2 and by 13 times in comparison to the bare rutile TiO2.

Dielectric barrier discharge simulation, Atmospheric pressure, Reactor gap, Relative permittivity, Surface treatment, Average power consumption, Physics, and QC1-999

Abstract In this study, effects of the variation in the dielectric barrier discharge’s (DBD) gap distance and the nature of dielectric layers which cover both of the reactor electrodes on the electron density, mass fraction of excited argon atoms across the discharge gap, mean electron energy, ion and electron current density, and electron temperature are investigated at atmospheric pressure. In order to find the optimal reactor gap, the DBD’s average power consumption is studied. The achievements show that when the value of dielectric constant is increased from 7.6 to 10, discharge gap of 1 mm still demonstrates the maximum power consumption, which can be considered as the optimum discharge gap. To optimize the characteristics of one-dimensional modeling of DBD system for material treatment, various types of materials with different values of the permittivity [aluminum, glass (quartz) and silicon] are embedded in the discharge gap between the two electrodes. In this case, the reactor gap is changed from 0.5 mm to 2 mm, while the dielectric constant of the dielectric layers which cover both of the metallic electrodes is assumed to be 10. Compared to the other examined materials, our numerical results illustrate that the treated material with higher value of the relative permittivity (silicon) has greater influences on the variations in the electron density, argon ion density and also total plasma current density than in the values of excited argon atom density, mass fraction of excited argon atoms and also average power consumption.