Surface Roughness Research Articles

The impact of different surface treatments on repair bond strength of conventionally, subtractive-, and additive-manufactured denture bases.

This study aimed to examine the shear bond strength (SBS) of repair material to conventionally, subtractive-, and additive-manufactured denture bases after different surface treatments. Disk-shaped test specimens (N = 300) were prepared from denture base materials produced by one conventional (Procryla), one subtractive (Yamahachi), and one additive (Curo Denture) method. The test specimens were randomly divided into five groups (n = 10) and exposed to a variety of surface treatments-Group A: no surface treatment; Group B: grinding with silicon carbide paper; Group C: sandblasting; Group D: erbium: yttrium-aluminum-garnet laser; and Group E: plasma. Repair was performed with autopolymerizing acrylic resin (Meliodent). Surface roughness analyses were performed with a profilometer. Scanning electron microscopy was used to examine one specimen from each subgroup. SBS was evaluated on a universal testing machine. Failure types were observed under a stereomicroscope. Surface roughness values were significantly higher in all test materials in Group D than in the other groups (p < 0.001). For conventional resin, the SBS values were higher in Group C than in Groups A, D, and E (p < 0.001). For CAD/CAM material, Groups B and C had significantly greater SBS increases compared with Group E (p < 0.001). For 3D material, Group D showed higher SBS than all groups except Group C (p < 0.001). For SBS, sandblasting was most effective in the conventional group, whereas laser treatment was the most effective in the additive-manufactured group. For the subtractive group, surface treatments other than plasma exhibited similar SBS. In repairing fractured prostheses, any degree of roughening suitable for the material content may provide an SBS benefit.

Improved Fog Collection on a Hybrid Surface with Acylated Cellulose Coating.

Fog collection serves as an efficient method to alleviate water scarcity in foggy, water-stressed regions. Recent research has focused on constructing a hybrid surface to enhance fog collection efficiency, with one approach being the prevention of liquid film formation at hydrophilic sites. Inspired by the desert beetle, a coating (10-MCC) made by partially acylating microcrystalline cellulose (MCC) exhibits hydrophilic sites alongside a hydrophobic skeleton enabling rapid droplet capture despite its overall hydrophobicity. The captured droplets quickly coalesce into a large droplet driven by the wetting gradient created by the hydrophobic backbone and hydrophilic sites. To achieve greater fog collection efficiency, a hydrophobic-superhydrophobic hybrid surface is formed by combining a coating of 10-MCC with a superhydrophobic surface. The construction of superhydrophobic surfaces typically involves creating a rough surface with a distinctive structure produced by the anodization technique and modifying it with stearic acid. The superhydrophobic surface exhibits excellent corrosion resistance and mechanical stability. Moreover, the hybrid surface shows high efficiency in fog collection, with a tested maximum efficiency of approximately 1.5092 g/cm2/h, 1.77 times that of the original Al sheets. The results demonstrate a remarkable enhancement in fog collection capacity. Furthermore, this work serves as an inspiration for the low-cost and innovative design of engineered surfaces for efficient fog collection.

Freezing of sessile water droplets on titanium alloy surfaces with various roughness: An in-situ experimental study

The threat of icing caused by supercooled water droplets on aircraft components such as wings and compressors is a serious concern for aviation safety, and the surface roughness of these components can experience alterations due to environmental corrosion or damage. However, the potential impact of surface roughness variation on their susceptibility to icing remains unclear. In this study, the freezing experiments of sessile water droplets on the surfaces of a typical aero-engine titanium alloy (ZTC4) with varying roughness were conducted using a laser confocal micro-Raman spectrometer with a heating/freezing stage. Three freezing stages were captured via an optical microscope, and the temperature changes of water droplet during the cooling process were explored through heat transfer simulation. In addition, the relationship between Raman peaks and temperatures of frozen droplets was quantified. The results of 200 repeated experiments demonstrated that the freezing temperatures of sessile water droplets exhibited a two-parameter Weibull distribution, and there was a nonlinear positive correlation between the mean freezing temperature and surface roughness, which implied that environmental corrosion or damage leading to an increase in surface roughness may significantly elevate the probability of component icing and safety issues.

Clinical effect of chlorhexidine and sodium fluoride on corrosion behavior and surface topography of nitinol orthodontic archwires

BackgroundAlterations in the mechanical properties of the materials utilized in orthodontic appliances could affect the working properties of the appliances, thereby affecting clinical progress and outcome. Numerous studies have confirmed the correlation between alloy corrosion and raised surface roughness, which has a direct impact on the working characteristics of orthodontic archwires.MethodsThirty nickel-titanium (NiTi) orthodontic archwires were utilized in this study. Patients were randomly selected and allocated into three groups according to the randomization plan; (The control group): subjects practiced regular oral hygiene; (The fluoride group): subjects used fluoride for intensive prophylaxis; (The chlorhexidine group): subjects used chlorhexidine. Representative samples were evaluated by SEM, and then SEM images with high resolution were examined using Image J software to determine the surface roughness and obtain the results for further statistical analysis.ResultsOur findings indicated a significant difference was found between the three groups regarding the anterior and posterior parts between the control and the two other groups and a non-significant difference between NaF and CHX groups. Overall, the p-value for group comparisons was 0.000 for both parts, indicating a highly significant difference especially between the control and NaF groups.ConclusionMouthwashes containing sodium fluoride demonstrated more significant surface alterations than the control and CHX groups and should be prescribed in accordance with orthodontic materials to reduce side effects.

Dental Restorative Materials and Halitosis: A Preliminary in-Vitro Study.

Despite the widespread use of dental restorative materials, little information exists in the literature regarding their potential impact on bad breath. This in vitro study aims to fill this gap by investigating the influence of different restorative materials on the release of hydrogen sulfide (H2S). Thirteen diverse dental restorative materials, including composites, flowable composites, glass ionomer restorative materials, high-copper amalgam, and CAD-CAM blocks, were examined. Cellulose Sponge models were used as negative and positive control. All samples were prepared with a diameter of 5 mm and a height of 2 mm. Except for the negative control group, all samples were embedded into Allium cepa L., and the emitted H2S was measured using the Wintact W8802 hydrogen sulfide monitor.&#xD;Surface roughness's effect on emission was explored by roughening the surfaces of CAD-CAM material samples, and gas emission was measured again. The data were statistically analyzed using the Kruskal-Wallis test and DSCF pairwise comparison tests. Fiber-reinforced flowable composite (EverX Flow), amalgam (Nova 70-caps), and certain composite materials (IPS Empress Direct, Tetric Evoceram, Admira Fusion X-tra) released higher H2S concentrations compared to the negative control. The H2S release period lasted longer in the same materials mentioned above, along with G-aenial Universal Injectable. Indirectly used materials, such as GC Cerasmart, Vita Enamic, and Vita YZ HT, demonstrated significantly lower emissions compared to other direct restoratives. Importantly, the surface roughness of indirect materials did not significantly affect peak H2S concentrations or release times. The study reveals variations in H2S release among restorative materials, suggesting potential advantages of indirect restorative materials in reducing H2S-induced halitosis.&#xD;This comprehensive understanding of the relationship between restorative materials and halitosis can empower both dental professionals and patients to make well-informed treatment choices. Notably, there is evidence supporting the enhanced performance of indirect restorative materials for individuals affected by halitosis.&#xD.

Inkjet-printed boron-doped poly-Si/SiOx passivating contacts

In this study, we explore the utilization of inkjet printing technology with liquid ink to fabricate boron-doped polycrystalline silicon (poly-Si)/SiOx passivating contacts. The impacts of substrate morphology, baseplate temperature, and surface oxide on the printing performance were investigated to achieve distinct printed patterns. Moreover, a pre-oxidation process at 750 °C for 30 min was conducted as a strategy to prevent dopant spreading from the printed pattern via the gas phase during the high-temperature annealing. Thereafter, the influences of annealing temperature on the formed poly-Si passivating contact quality were studied. By applying optimized process conditions on intrinsic poly-Si(i-poly-Si)/SiOx/p-type crystalline Si (c-Si) substrates, promising surface passivation was achieved with an implied open-circuit voltage (iVoc) of 718 mV and a low contact resistivity (ρc) of 6.1 mΩ cm2 after annealing at 950 °C followed by a hydrogenation treatment. Optical images demonstrate that single-droplet dopant lines with a width of 69 μm could be realized on a mechanically polished substrate by printing with a drop spacing of 40 μm, while the line width expands on rough surfaces or when printing with a reduced drop spacing. Furthermore, high-resolution micro-photoluminescence maps clearly illustrate the localization of the boron-doped regions on polished and planar substrates after annealing. We also realized the formation of localized inkjet-printed phosphorus- and boron-doped poly-Si passivating contacts simultaneously within a single annealing step at 950 °C. These findings underscore the potential of inkjet printing as a promising technique for fabricating localized poly-Si/SiOx passivating contacts in high-efficiency silicon solar cells.

Long-term performance of chemically modified cotton straw fibers in micro-surfacing asphalt mixtures

Using agricultural wastes in asphalt pavements presents a promising solution to enhance pavement performance and utilize agricultural wastes simultaneously. In the paper, the fibers are made from recycled cotton stalks. Chemical modifiers are chosen to enhance the adherence of fiber asphalt binders. Different modified fibers are added to the SBR-modified emulsified asphalt. The modified asphalt binders are then utilized to prepare asphalt mixtures. Comparative studies on construction performance, road performance, and durability were carried out. Results showed that water consumption and bitumen aggregate ratio at the micro-surfacing were increased after adding fiber. Fibers with low hygroscopicity, rough surface, and high asphalt absorption rate had better adhesion properties. The long-term performance of a micro-surfacing mixture was most remarkably improved by the CH3COOH-modified cotton straw fibers, demonstrating a 10.07% drop in rutting depth, a 9.13% decrease in abrasion value, and a 41.13% gain in shear resistance compared to the micro-surfacing mixtures with unmodified fibers. The study concluded that modified fiber micro-surfacing asphalt mixes are more suitable for seasonal frozen regions than the conventional mixes. The findings offer a theory foundation for the future development of cotton straw fibers in road engineering.

A Study on the Performance, Structure, Composition, and Release Behavior Changes of Polybutylene Adipate Terephthalic Acid (PBAT) Film during Food Contact

Polybutylene adipate terephthalic acid (PBAT) is an emerging biodegradable material in food packaging. However, concerns have been raised regarding the potential hazards it could pose to food safety. In this study, the changes of PBAT films during food contact and the release of small molecules were inestigated by a multiscale approach. On a macro-scale, the surface roughness of the films increased with the reduction in the concentration of food simulants and the increase in contact temperatures, especially after immersion in acidic food environments. On a micro-scale, the crystallinity (Xc) and degradation indexes (DI) of the films increased by 5.7% - 61.2% and 7.8% - 48.6%, respectively, which led to a decrease in thermal stability. On a scale approaching the molecular level, 2,4-di-tert-butylphenol (2,4-DTBP) was detected by gas chromatography-mass spectrometry (GC-MS/MS) with the highest migration content, and the release behavior of 2,4-DTBP was further investigated by migration kinetics. In addition, terephthalic acid (TPA), a hydrolysis product of PBAT, was detected in acidic food environments by liquid chromatography-mass spectrometry (LC-MS/MS). The results of this study could provide practical guidance and assistance to promote sustainable development in the field of food packaging. Environment ImplicationPBAT film is a new biodegradable material in food packaging that may release small molecular during its contact with food, and pose potential risks to human health. In this study, PBAT films were immersed in a variety of food simulants, and it was found there released a variety of small molecules including TPA, resulting from the hydrolysis of PBAT. The study also revealed that some of these small molecules inhibited cell growth. These findings could promote the safe application of PBAT films in food packaging.

A turbidity-based study of removing polyvinyl chloride nanoplastics using magnetic biochar

Magnetic biochars (MBCs) can quickly and efficiently remove polystyrene nanoplastics (NPs) from water. However, the removal efficiency of other types of NPs by different MBCs remains unknown. In this study, the removal performance of polyvinyl chloride NPs (PVC-NPs) by magnetic corncob biochar (MCCBC) and magnetic walnut shell biochar (MWSBC) was evaluated by measuring turbidity. The results indicate rapid adsorption of PVC-NPs onto MCCBC and MWSBC, reaching equilibrium within 1 h. The removal efficiencies of PVC-NPs by MCCBC and MWSBC were 94% and 92%, respectively. The relatively higher PVC-NPs removal capacity by MCCBC resulted from the greater amount of iron oxide on its surface, creating a rougher surface. The presence of monovalent ions (K+, Na+, Cl-, NO-3) promoted the removal of PVC-NPs by MWSBC, but caused a reduction in the adsorption of PVC-NPs on MCCBC. In contrast, divalent ions (Mg2+, Ca2+, and SO2-4) significantly inhibited the removal efficiency of PVC-NPs by competing for adsorption sites on MBCs (p < 0.01). Increasing the ionic strength inhibited the removal efficiency of PVC-NPs by MBCs. In addition, the highest removal efficiency of PVC-NPs was obtained at pH 5.0–7.0. Apart from adsorbing onto the surface of MBCs and becoming trapped within their pores, PVC-NPs can be magnetized by iron oxides. Moreover, PVC-NPs could aggregate with the small fragments of MBCs, thus allowing for easy removal by a magnet. The results provide new insight into the investigation of techniques to remove NPs other than PS from water.

Effect of Bleaching on Surface Roughness and Color Parameters of Coffee-Stained Nanohybrid Dental Composites with Different Viscosities

Abstract Objective The aim of this study was to test the effect of different bleaching protocols on surface roughness, color stability, and translucency parameter of coffee-stained nanohybrid dental composites with different viscosities. Materials and Methods Five nanohybrid dental composites with different viscosities (n = 250)—Neo Spectra LV, Neo Spectra HV, Neo Spectra Flow (Dentsply, Konstanz, Germany), Grandio, and Grandio Flow (Voco, Cuxhaven, Germany)—were used to test surface roughness, color stability, and translucency parameter after bleaching of coffee-stained specimens using either in-office bleaching, home bleaching, or a combination of both. The viscosity of the five types of dental composites was tested using a viscometer. A scanning laser microscope (SLM) was used to examine the surface topography of representative samples from each dental composite after the combined effect of both bleaching agents. Effect of composite type, bleaching protocol, and their interaction was assessed by two-way analysis of variance. For multiple comparisons, Tukey's post hoc test was used with Bonferroni correction. Results Surface roughness of all coffee-stained dental composites increased after bleaching; however, those of Grandio and Grandio Flow increased significantly (p &lt; 0.0001). This was confirmed by SLM images that showed rough surface with protruding fillers after in-office and home bleaching protocol. Results revealed that bleaching, regardless of the protocol, decreased the delta E values of all dental composites; however, it was still higher than the accepted threshold value of 3.7. Neither of the bleaching protocols enhanced translucency parameter of all dental composites. Neo Spectra Flow and Voco Flow had the highest translucency parameter after the three bleaching protocols. Conclusion Bleaching does not improve color stability and translucency of coffee-stained nanohybrid dental composites regardless of the viscosity. Surface roughness of coffee-stained nanohybrid dental composites increases after application of bleaching agents.

Exploring the effectiveness of negative and positive inserts in machining Inconel 718 alloy: a comparative study

AbstractInconel 718 alloy is characterised by high strength and corrosion resistance and remains stable at high temperatures, so it is widely used in the energy and aerospace industries. However, machining this material is difficult due to its high strength, hardness, and high specific force coefficient exceeding 3000 MPa. Turning of the Inconel 718 alloy can be carried out with negative and positive inserts. Therefore, the impacts of the insert geometry on the turning process of Inconel 718, cutting force components, and surface roughness were studied. Three positive and three negative insert geometries were tested. It was shown that the key influence on the active components of the cutting force is the effective rake angle. The surface roughness, on the other hand, depends mainly on the cutting-edge radius. It has been shown that the negative insert geometry with γ = 6° and rn=22 μm provides a 30% lower cutting force than the positive inserts and the same surface roughness. The developed models of the cutting force components proved that when cutting with positive inserts, a higher specific cutting force occurs for the Inconel 718 alloy than for the negative insert. It was shown that technological parameters had a very similar effect on the cutting force components and surface roughness parameters regardless of the blade geometry. It was proven that the use of positive inserts makes sense only for depths of cut no greater than the size of the corner radius.

Influence of spatial engagement angles on machining forces and surface roughness in turning of unidirectional CFRP

Carbon fibre-reinforced polymer (CFRP) is being widely used due to its low specific weight and outstanding mechanical properties. However, using identical machining parameters on unidirectional CFRP can lead to different results depending on the fibre orientation.Recently, a process-independent model describing the engagement conditions in oblique cutting of unidirectional CFRP has been developed, introducing the spatial angles θ0 and φ0. Since the engagement conditions of milling and drilling are complex, analogy experiments are conducted in turning with variation of the setting κrand inclination angles λs. In this study, process forces and surface roughness were measured as a function of the complete range of fibre cutting angle θ.

Research on formation mechanism and output effect of wind turbine ice-covered blades

Considering the physical characteristics of wind turbine wing icing, icing synthesis rate, and icing type, we selected the icing type and surface roughness of ice-coated blades as sensitive parameters. The focus of our research was on the equivalent particle roughness height correction model, and we numerically analyzed the two icing processes (frost ice and clear ice) on wind turbine blade surfaces by combining FENSAP-ICE and FLUENT analysis tools. We predicted the ice type on blade surfaces using a multi-time step method and analyzed how variations in icing shape and ice surface roughness affect the aerodynamic performance of blades during frost ice formation or clear ice formation. Our results indicate that differences in blade surface roughness and heat flux lead to disparities in both ice formation rate and shape between frost ice and clear ice. Clear ice has a greater impact on aerodynamics compared to frost ice, while frost ice is significantly influenced by the roughness of its icy surface. These findings can serve as valuable references for wind power operators and manufacturers seeking solutions to issues related to blade surface icing under extremely cold conditions.

An integrated experimental and analytical approach on mechanical characterization of advanced powder metallurgy aluminium metal matrix composites reinforced with different particulates

Abstract Over the last few decades, “Discontinuously Reinforced Particulate Composites (DRPCs)” are a popular class of composite materials with considerable challenge in processing, characterization and machinability because of their increased strength-weight ratio, stiffness, specific strength and oxidization when compared to various metals and their alloys. This paper discusses experimental and numerical investigation on mechanical characteristics of aluminum metal matrix reinforced with various reinforcement particulates such as silicon carbide, aluminium oxide, and zirconium oxide, compaction pressure (kN) and hold time (s) based on Design of Experiments (DOE) and Finite Element Analysis. Initially this paper discusses the process optimization of Aluminum Matrix reinforced with different particulates experimentally to identify the favourable processing conditions by varying reinforcement materials, compaction pressure (kN) and hold time (s) based on TDOE (Taguchi’s Design of Experiments). Further, this paper concentrates to determine “maximum principal stress, equivalent elastic strain and equivalent (von-mises) stress” based on Finite Element Analysis (ANSYS Workbench-2023R1). The results of the experimentation showed that the highest hardness values were achieved with ZrO2 reinforcement material. Increasing the compaction pressure from 8 to 12 kN resulted in a slight decrease in surface roughness and porosity. Higher compaction pressures have assumed to facilitate better particle distribution and improved interfacial bonding, leading to smoother surfaces and lower void content. The simulation results showed that the maximum principal stress achieved were (2235.8 Mpa) SiC, (3444.4 Mpa) Al2O3, and (3582.5 MPa) ZrO2. The equivalent elastic strain achieved was (0.2488) SiC, (0.2421) Al2O3 and (0.262) ZrO2. The equivalent (Von Mises) stress achieved was (28751 MPa) for SiC, (24880 MPa) for ZrO2 and (26972 Mpa) for Al2O3. This experimentation and simulation demonstrated that the PM process can be used to fabricate DRAMMC with different reinforcement particulates.

Nanomechanical and Microstructural Characterization of Biocompatible Ti3Au Thin Films Grown on Glass and Ti6Al4V Substrates.

Ti-Au intermetallic-based material systems are being extensively studied as next-generation thin film coatings to extend the lifetime of implant devices. These coatings are being developed for application to the articulating surfaces of total joint implants and, therefore, must have excellent biocompatibility combined with superior mechanical hardness and wear resistance. However, these key characteristics of Ti-Au coatings are heavily dependent upon factors such as the surface properties and temperature of the underlying substrate during thin film deposition. In this work, Ti3Au thin films were deposited by magnetron sputtering on both glass and Ti6Al4V substrates at an ambient and elevated substrate temperature of 275 °C. These films were studied for their mechanical properties by the nanoindentation technique in both variable load and fixed load mode using a Berkovich tip. XRD patterns and cross-sectional SEM images detail the microstructure, while AFM images present the surface morphologies of these Ti3Au thin films. The biocompatibility potential of the films is assessed by cytotoxicity tests in L929 mouse fibroblast cells using Alamar blue assay, while leached ion concentrations in the film extracts are quantified using ICPOEMS. The standard deviation for hardness of films deposited on glass substrates is ∼4 times lower than that on Ti6Al4V substrates and is correlated with a corresponding increase in surface roughness from 2 nm for glass to 40 nm for Ti6Al4V substrates. Elevating substrate temperature leads to an increase in film hardness from 5.1 to 8.9 GPa and is related to the development of a superhard β phase of the Ti3Au intermetallic. The standard deviation of this peak mechanical hardness value is reduced by ∼3 times when measured in fixed load mode compared to the variable load mode due to the effect of nanoindentation tip penetration depth. All tested Ti-Au thin films also exhibit excellent biocompatibility against L929 fibroblast cells, as viability levels are above 95% and leached Ti, Al, V, and Au ion concentrations are below 0.1 ppm. Overall, this work demonstrates a novel Ti3Au thin film system with a unique combination of high hardness and excellent biocompatibility with potential to be developed into a new wear-resistant coating to extend the lifetime of articulating total joint implants.

Effect of Particle Size on Optical and Electrical Properties of Thin Films – A Simulation Approach

Abstract This work presents a simulated investigation of the relationship between surface roughness and particle size as well as the resulting impact on the thin film's physical, optical, and electrical properties. Non-porous thin films are created through computer simulation for a range of particle sizes. Random deposition with a surface relaxation technique is used for the generation of non-porous thin films. The fundamental data of two well-known materials, ZnO and CdSe, were used for the theoretical calculation of different parameters like bandgap, absorption coefficient, refractive index, dielectric constant conductivity, or others. It is also shown that the pre-assumed values of all these parameters are well matched with the experimental results reported by different groups. This is probably the first effort to develop a direct relation between the particle size with different fundamental optical or electrical properties of different materials. This would definitely help the experimental researchers in the field of material science to design their experiments as per the desired requirements.&amp;#xD;&amp;#xD;

Investigation of Micropattern Forming Process on Zr‐4 Alloy Surface Considering Plowing Effects

Micropattern forming process is an efficient and low‐cost process for fabricating multifunctional surfaces in electronics, energy, and biomedical products, but this process of creating microdimples on the surface of zirconium alloys has not been investigated. Currently, there are few models describing the micropattern forming process, and these existing models have not considered the effect of roughness on forming. The influence of roughness on micropattern forming process is not to be neglected due to the size effect, especially the plowing effects caused by asperities in surface roughness during sliding process. In this article, a micropattern forming process model is developed by combining a rough plane indentation model and a plowing effects model, and the experimental study of the forming process is conducted, which can quantitatively evaluate the effects of different process parameters and different roughness of forming die on forming process. The applicability range of the developed model is obtained, and the model is capable of predicting the forming process with various process parameters and surface roughness of forming die by comparing the experiment results with the model results, which is of great significance to the design of the forming die and the improvement of the forming process.

Synergistic effect of ZnO nanocomposite of Dodonea viscosa for corrosion inhibition in saline media

Abstract Dodonea viscosa-zinc oxide (DV-ZnO) nanocomposite was synthesized and characterized using Fourier transform infrared (FTIR), thermal gravimetric method (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The most abundant compounds in the plant extract were explored using gas chromatography-mass spectrometry (GC-MS). FTIR indicated the existence of the different functional groups, XRD showed that the nanocomposite has the hexagonal wurtzite shape of ZnO nanoparticles, SEM-EDS showed a size of 50 nm, and elemental analysis depicts the existence of the different elements in the extract, which confirms, along with TGA results, the formation of DV-ZnO nanocomposite. The nanocomposite synergistic effect was examined for anticorrosion capabilities using gravimetric, electrochemical, and surface analysis methods. Both the plant extract and the nanocomposite exhibited corrosion inhibition abilities. However, the incorporation of the plant extract with ZnO increased the inhibition efficiency by 20 %. Weight loss and electrochemical methods concluded an inhibition efficiency of 80 % for DV-ZnO nanocomposite. The inhibition of the nanocomposite is due to the adsorption of the inhibitor on the carbon steel surface, which was verified using X-ray photoelectron spectroscopy and scanning electron microscopy (SEM). The adsorption was found to follow both Langmuir and Temkin isotherms. Surface examination using atomic force microscopy (AFM) found that the carbon steel surface roughness was decreased from the sample submerged in an uninhibited medium (Sa = 121.20 nm) when adding DV-ZnO nanocomposite (Sa = 22.95 nm) and DV plant extract inhibitor (Sa = 54.73 nm).

Rainband‐Occurrence Probability in Northern Hemisphere Tropical Cyclones by Synthetic Aperture Radar Imagery

AbstractRainbands are essential to tropical cyclones (TCs), significantly affecting TC structure and intensity change. High‐resolution synthetic aperture radar (SAR) imagery can capture the footprints of rainbands caused by rain‐induced sea surface roughness modification. Using 464 SAR TC images, we investigated the rainband‐occurrence probability of TCs under different hemispheres, local times (LTs), intensities, and ocean basins. Results show that the rainband‐occurrence probability is highest in the downshear‐left quadrant for Northern Hemisphere TCs (downshear‐right quadrant for Southern Hemisphere TCs). For Northern Hemisphere TCs, the rainband‐occurrence probability is overall higher in the early morning (LT), and the peak region of rainband‐occurrence probability appears farther from the TC center in the evening (LT). Compared with weak TCs, the rainband‐occurrence probability becomes higher for strong TCs in the Northern Hemisphere. Furthermore, TCs have a higher rainband‐occurrence probability in the Northwest Pacific than in the North Atlantic and Northeast Pacific.

Effect of electric mode of micro-arc oxidation on structural and phase state of calcium-phosphate coating

Abstract The micro-arc oxidation method has been used to obtain bioactive calcium-phosphate coatings on titanium surface. The effect of the pulse current duty cycle and voltage of micro-arc oxidation on the morphology, elemental and phase composition of the coating has been studied. Decrease in the pulse duty cycle during microarc oxidation results in the formation of flake, spheroidal and lamellar structures. It has been shown that the Ca/P ratio and surface roughness of the coating increases regardless of the pulse duty cycle with increase of applied voltage. Depending on the application mode, the Ca/P ratio and the roughness of calcium phosphate coatings ranged from 0.44 to 0.67 and from 4.2 to 6.8 μm, respectively. It was found that change of the pulse current duty cycle and increase of the voltage up to 600 V results in the formation of the main crystalline phases Ca(H2PO4)2(H2O) and CaPO3(OH) in the coatings.&amp;#xD;