Smooth Surface Research Articles

Valence band-tunable NiFe electrocatalyst triggered by the dynamic Mo exudation and re-deposition for superior high current density oxygen evolution reaction.

Developing energy- and time-efficient strategies to derive high-performance non-precious electrocatalysts for anodic oxygen evolution reaction (OER), especially stably working at industrial-demanding current density, is still a big challenge. In this work, a concise molten salt erosion scenario was devised to rapidly modulate the smooth surface of the commercial NiMo foam substrate into the rough, electronically coupled, and hierarchically porous Ni/Fe/Mo(oxy)hydroxide catalyst layer assembled by the nanosphere array. This self-supported catalyst is super-hydrophilic for the alkaline electrolyte and distinguished by a balanced Mo leaching/surface-readsorption process to tune the metal d band center and electronic perturbation. The altered electronic environment with the favored OER intermediate adsorption behavior attains the outstanding OER activity in terms of a very small overpotential of 230.21 mV at 10 mA cm-2 and an ultra-long stability for 1179.45 h to sustain the initial commercial-level current density of ca. 1000 mA cm-2. This superb performance transcends most of the edge-cutting transition metal peers reported recently and can satisfy the standards of industrial applications. This industrial-compatible synthesis technology holds profound implications for hydrogen production via water splitting and other electrochemical applications.

Simulation-based research on enhancing lubricity: investigating wettability and textured surfaces in alkane lubricants under boundary lubrication conditions.

Changing the wettability and surface texturing have a significant impact on lubrication. In this study, the researchers used the molecular dynamics (MD) method to investigate how adjusting the interaction between alkanes and the wall affects oil film morphology and frictional properties under boundary lubrication. The findings revealed that the bearing capacity was influenced by both the morphology of the oil film and the strength of solid-liquid adsorption. In cases where the walls had weak wettability, the alkanes formed clusters to effectively separate the walls, while in cases where the walls had strong wettability, the oil film spread and formed a strong adsorption film. The super oleophilic textured surface could enhance the oil film adsorption capacity and replenish the oil film to the friction area in time, and the super oleophobic smooth surface could further reduce the friction coefficient. Therefore, a composite surface consisting of a super oleophilic textured surface and a super oleophobic smooth surface can be designed to enhance the bearing capacity of the oil film and reduce friction.

The role of manufacturing-induced texture on the tribological performance of cold work tool steels

Manufacturing operations produce surface characteristics that, although stochastic, can significantly affect functionality, especially in forming tools, impacting contact and lubrication conditions during operation. This study investigates the influence of stochastic microtextures resulting from milling on the tribological performance of cold work tool steels with two different carbon contents (0.8 and 2 wt%). Different surface textures were observed resulting from the different C contents, with 3D roughness parameters indicating rougher surfaces for the 2.0% wt. C steel. Tribological behavior was assessed using the strip drawing test to analyze friction, wear coefficients, and wear mechanisms. Surface analysis before and after testing was executed employing SEM, EDX, and CLSM, with CLSM also used to determine 3D roughness parameters of the worn tracks. Post-test macrographic analyses and 2D roughness measurements were conducted on the pulled sheets. Tribological test data revealed lower friction and wear coefficients for the 2.0 wt% C tool steel, with susceptibility to abrasion wear, while the 0.8 wt% C tool exhibited a higher tendency towards adhesion wear. Post-test analysis suggested smoother surfaces for the 2.0 wt% C steel compared to the 0.8 wt% C steel. Macrographic analysis showed no visible wear marks on sheets tested with the 2.0 wt% C steel, contrasting with wear grooves visible on sheets pulled against the 0.8 wt% C steel. Additionally, 2D roughness measurements indicated higher roughness after pulling against the 0.8 wt% C tool compared to the 2.0 wt. C tool. Overall, the study demonstrates that manufacturing-induced textures without the need of post-manufacturing texturing influence the tribological performance of the evaluated steels, opening an avenue to be explored to improve the tribological performance of forming tools.

Enzymatically and chemically starch nanoparticles preparation using ultrasonication, precipitation and lyophilization post-treatments: Screening and characterization

Starch nanoparticles (SNPs) have been used in food emulsions as natural stabilizer and emulsifier. SNPs in colloidal form were produced using enzymatically, acidic and alkaline hydrolyses in combination to ultrasonication and precipitation methods. X-Ray diffraction test for produced SNPs indicated that enzymatically and acidic prepared SNPs had amorphous structure while, the resulted SNPs using alkaline hydrolysis had lower relatively crystallinity. Results indicated that, enzymatically prepared SNPs, had minimum particle size (225 ± 10 nm) and polydispersity index (0.472 ± 0.05), and maximum zeta potential (−26.3 ± 1 mV), antioxidant activity (3.36 ± 0.05 %) and specific surface area (1.8 ± 0.1 m2g−1). Transmission electron microscopy revealed that prepared SNPs had spherical shape and enzymatically prepared SNPs had mean particle size of <100 nm. SNPs in powder form were prepared using freeze drying (pressure and temperature of 100 Pa and − 70 °C). Atomic force microscopy results demonstrated that starch granules had smooth surface, with polyhedral shape and particle size ranging 5 to 25 μm, and after hydrolysis, SNPs had particle size in nanometer scale. Emulsion ability test indicated that oil separation time from the prepared emulsions containing 10 % (W/V) starch, and enzymatically, acidic and alkaline prepared SNPs powder were 41, 70, 82 and 101 s, respectively.

Diffusion of Carbon Quantum Dots on Lithium Liquid Metal for Artificial SEI

AbstractThe unstable solid electrolyte interface (SEI) formed on the surface of Li metal can induce dendrite growth, resulting in capacity fading, battery short circuit, and other problems, thus hindering the practical application of Li metal battery. In order to obtain stable and effective SEI, it is an effective strategy to construct an ideal artificial SEI (ASEI) by regulating the composition and structure of the interface. Among the inorganic materials used in the construction of ASEI, carbon quantum dots (CQDs) stand out as promising material due to their small size and abundant active sites. Herein, benefiting from the fluidity, surface smoothness, and high reactivity of liquid metal, combined with the use of N‐doped CQDs as dispersing particles, a surface modification method to achieve uniform dispersion of particles within the liquid metal is proposed. This technique offers a low‐cost solution for achieving uniform dispersion of little quantities of N‐doped CQDs (single dose &lt; 0.1 mg cm−2) while ensuring enhanced interface adhesion to realize the construction of dense, strong and uniform ASEI. The corresponding symmetrical cells show lower voltage polarization and outstanding cycling stability than the bare Li electrode.

Exploring the therapeutic potential of urine-derived stem cell exosomes in temporomandibular joint osteoarthritis.

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative ailment that causes slow cartilage degeneration, aberrant bone remodeling, and persistent discomfort, leading to a considerable reduction in the patient's life quality. Current treatment options for TMJOA have limited efficacy. This investigation aimed to explore a potential strategy for halting or reversing the progression of TMJOA through the utilization of exosomes (EXOs) derived from urine-derived stem cells (USCs). The USC-EXOs were obtained through microfiltration and ultrafiltration techniques, followed by their characterization using particle size analysis, electron microscopy, and immunoblotting. Subsequently, an invivo model of TMJOA induced by mechanical force was established. To assess the changes in the cartilage of TMJOA treated with USC-EXOs, we performed histology analysis using hematoxylin-eosin staining, immunohistochemistry, and histological scoring. Our findings indicate that the utilization of USC-EXOs yields substantial reductions in TMJOA, while concurrently enhancing the structural integrity and smoothness of the compromised condylar cartilage surface. Additionally, USC-EXOs exhibit inhibitory effects on osteoclastogenic activity within the subchondral bone layer of the condylar cartilage, as well as attenuated apoptosis in the rat TMJ in response to mechanical injury. In conclusion, USC-EXOs hold considerable promise as a potential therapeutic intervention for TMJOA.

Interface improvement of diamond/copper composites through a low-temperature high-efficiency coating method

A tungsten coating was formed by the in situ reaction of tungsten trioxide formed by the thermal decomposition of ammonium metatungstate in a molten salt (NaCl+BaCl2) environment with carbon atoms on the surface of diamond. Meanwhile, diamond/copper composites were prepared using the prepared tungsten-coated diamonds. The morphology and composition of the coatings and diamond/copper composites were observed using scanning electron microscopy, transmission electron microscopy, and energy-dispersive spectroscopy. The results revealed that the originally smooth diamond surface was uniformly covered by a tungsten coating after low-temperature salt bath treatment at 1050 °C, a temperature 50–100 °C lower than that of traditional methods. Compared to the directly added tungsten trioxide, the tungsten trioxide produced by the thermal decomposition of ammonium metatungstate was more active, and the coating was more uniform. The bending strength and thermal conductivity of tungsten-coated diamond/copper composites were 280.6 MPa and 516 W/(m·k), respectively, which were significantly higher than those of uncoated diamond/copper composites (128.6 MPa and 168 W/m·K). This indirectly confirms that the diamond surface coating can improve the interfacial bonding performance between diamond and copper.

Diffraction by gratings: from the C-method to the stochastic C-method

The Chandezon, or C-method, is an efficient and versatile numerical method for modeling diffraction problems involving smooth surface relief gratings. For some grating profiles, the C-method is limited when the height-to-period ratio exceeds a factor of three. This is due to the formation of ill-conditioned matrices for inversion. Here, the stochastic C-method (SCM) is introduced as a solution that leverages stochastic differential equations to overcome these numerical difficulties. The SCM is developed by altering the physical model of the grating profile function to include an additive Brownian noise component. The inclusion of noise dramatically expands the applicability of the C-method and enriches the physical model. Numerical experiments show that the SCM achieves a precision on the order of 10−5 for diffracted/transmitted amplitudes on sinusoidal profiles with height-to-period ratios as high as 72. These results are in agreement with those obtained using multi-precision and the rigorous coupled wave analysis (RCWA).

Proposal for Surface Smoothing of Additive Manufactured Cooling Channel with Electrochemical Machining and Basic Research on Its Application to Straight Holes

Proposal for Surface Smoothing of Additive Manufactured Cooling Channel with Electrochemical Machining and Basic Research on Its Application to Straight Holes

Sputtering Coefficients of Beryllium and Tungsten by Various Atoms from Hydrogen to Tungsten

Using computer simulation, the sputtering coefficients of Be and W targets, promising materials for the first wall and divertor in the ITER tokamak, are calculated in a wide range of incident atom energies 10–100 000 eV. The following atoms were chosen as projectiles: H, D, T, He, Be, C, N, O, Ne, Ar, W. A strong influence of the surface profile on the results obtained is shown. The limiting cases of a planar potential barrier (smooth surface) and a spherical potential barrier (rough surface) are considered. Data on the average energy and angular distributions of sputtered atoms were obtained, which are necessary for calculating the influx of impurities into the tokamak plasma. The influx of wall material atoms into the ITER tokamak plasma is estimated when the wall is sputtered by flows of fast deuterium and tritium atoms leaving the plasma.

One-step fabrication of multifunctional superhydrophobic copper surfaces via laser-assisted ablation PDMS solution

The super-hydrophobic surfaces have been greatly restricted in multi-functional applications because of the poor surface durability and multi-step processes such as preparing rough structures and low surface energy modification. In this work, a multifunctional wear-resistant super-hydrophobic surface (SHS) was primarily developed by one step laser etching polydimethylsiloxane (PDMS) i.e. the uncured PDMS layer was laser-ablated just after it was coated on the surface of copper. The wettability, morphology and chemical composition of the surfaces were characterized by a contact Angle measuring instrument, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR). The results show that the developed SHS has the high contact angle (WCA) of 156.8° and low sliding angle (WSA) of 4.6°; which presents a regular linear grating array and a large number of coral-like rough structures, and the developed SHS can withstand at least 120 tape stripping tests, 40 sandpaper friction abrasion tests, 60 h of high temperature treatment (100 °C∼300 °C) or 240 h of ultraviolet light exposure tests, respectively. The self-cleaning rate and anti-fouling rate of the SHS were 94.2 % and 91.8 %, respectively, and the freezing time of droplets on the SHS is 162 s longer than that on the original copper surface, and almost 3 times longer than that on the smooth surface. In all, the non-polluting wear-resistant multifunctional SHS was primarily developed by laser ablation of metals and polymers, which has strong potential usage in the fields of anti-fouling of industrial pipeline systems and anti-icing of outdoor power transmission systems.

Functional of thin-film composite Janus membrane with sacrificial layer for inorganic scaling control in membrane distillation

Membrane distillation technology, utilized for treating hypersaline wastewater from seawater desalination, often encounters challenges related to inorganic scaling, adversely affecting membrane performance. Herein, we introduce a innovative approach employing a sacrificial layer on the surface of Thin Film Composite (TFC) membranes to concurrently enhance inorganic scaling resistance and facilitate membrane reusability. The sacrificial layer (Fe3+-TA) consisted of tannic acid (TA) complexed with iron ions (Fe3+) and could be removed and regenerated in situ. The results demonstrated that the Fe3+-TA layer significantly improved the membrane's surface smoothness and densification, maintaining superior anti-scaling performance. The modified membrane exhibited remarkable durability, sustaining six reuse cycles with a flux recovery exceeding 97 % in gypsum scaling tests. Furthermore, the formation of new complexes during gypsum scaling tests confirmed the membrane's augmented scaling retardation capabilities. Thus, integrating of a sacrificial layer into TFC membranes presents a promising strategy for advancing membrane distillation processes in hypersaline wastewater treatment.

Galois skew lines of smooth surfaces in P 3

It is known that the degree of irrationality irr ( X ) of a smooth surface X of degree d ≥ 5 in P 3 is at least d – 2. In this paper, we study a Galois rational map f : X − − → P 2 of degree d – 2, and we show that the Galois group of f is a cyclic group, and f is defined by the family of lines intersecting two fixed skew lines. In addition, we give a necessary and sufficient condition that X has skew lines which give a Galois rational map of degree d – 2 by using automorphisms of X.

In-situ geochemical and isotopic analyses of multiple pyrite generations: Insights for the giant Beiya Au polymetallic ore genesis in southwestern China

The Beiya giant Au polymetallic deposit is located in the Sanjiang Tethyan Orogen, northwestern Yunnan (SW China). The ores occur as disseminations or veinlets in granite porphyry. To unravel the ore genesis at Beiya, we analyzed the ore-related sulfide trace elements and sulfur isotopes. Py-1 is mainly euhedral-subhedral medium-/coarse-grained (size: > 100 μm), with relatively smooth surface and some pores. Py-2 is mostly coarse grained (size: 50–200 μm), with well-developed pores and inclusions. The pyrite is usually Co-Cu rich and V-Ti-Sb poor, resembling typical magmatic-hydrothermal pyrite. In addition, the Co/Ni ratios decrease from pyrite-1 (Py-1) to pyrite-2b (Py-2b), suggesting that their chemical compositions are controlled by magma fractionation. We found that Co, Ni, As, and Se occurred as solid solution in the pyrite lattice, while Pb, Bi, Ag, and Mn occurred mainly in inclusions in the pyrite. Pb and Bi display good positive correlation, suggesting that they occurred as inclusions or nano-particles in pyrite lattice. The pyrite samples have sulfur isotope value (δ34S) of 0.62–3.45 ‰ (avg. 2.35 ‰) for Py-1, 0.18–3.12 ‰ (avg. 1.85 ‰) for Py-2a, and 0.62–4.18 ‰ (avg. 2.51 ‰) for Py-2b. These characteristics may have played a vital role in the initial enrichment of Cu, Mo, Au, and ultimately formed the complex polymetallic system at Beiya.

Patching Non-Uniform Extraordinary Points.

Smooth surfaces from an arbitrary topological control grid have been widely studied, which are mostly generalized from splines with uniform knot intervals. These methods fail to work well on extraordinary points (EPs) whose edges have varying knot intervals. This article presents a patching solution for arbitrary topological 2-manifold control grid with non-uniform knots that defines one bi-cubic Bézier patch per control grid face except those faces with EPs. Experimental results demonstrate that the new solution can improve the surface quality for non-uniform parameterization. Applications in surface reconstruction, arbitrary sharp features on the complex surface and tool path planning for the new surface representation are also provided in the paper.

Relationship Between Nonsmoothness in Adversarial Training, Constraints of Attacks, and Flatness in the Input Space.

Adversarial training (AT) is a promising method to improve the robustness against adversarial attacks. However, its performance is not still satisfactory in practice compared with standard training. To reveal the cause of the difficulty of AT, we analyze the smoothness of the loss function in AT, which determines the training performance. We reveal that nonsmoothness is caused by the constraint of adversarial attacks and depends on the type of constraint. Specifically, the L∞ constraint can cause nonsmoothness more than the L2 constraint. In addition, we found an interesting property for AT: the flatter loss surface in the input space tends to have the less smooth adversarial loss surface in the parameter space. To confirm that the nonsmoothness causes the poor performance of AT, we theoretically and experimentally show that smooth adversarial loss by EntropySGD (EnSGD) improves the performance of AT.

Evaluation of lamin A/C mechanotransduction under different surface topography in LMNA related muscular dystrophy.

Most of the single point mutations of the LMNA gene are associated with distinct muscular dystrophies, marked by heterogenous phenotypes but primarily the loss and symmetric weakness of skeletal muscle tissue. The molecular mechanism and phenotype-genotype relationships in these muscular dystrophies are poorly understood. An effort has been here to delineating the adaptation of mechanical inputs into biological response by mutant cells of lamin A associated muscular dystrophy. In this study, we implement engineered smooth and pattern surfaces of particular young modulus to mimic muscle physiological range. Using fluorescence and atomic force microscopy, we present distinct architecture of the actin filament along with abnormally distorted cell and nuclear shape in mutants, which showed a tendency to deviate from wild type cells. Topographic features of pattern surface antagonize the binding of the cell with it. Correspondingly, from the analysis of genome wide expression data in wild type and mutant cells, we report differential expression of the gene products of the structural components of cell adhesion as well as LINC (linkers of nucleoskeleton and cytoskeleton) protein complexes. This study also reveals mis expressed downstream signaling processes in mutant cells, which could potentially lead to onset of the disease upon the application of engineered materials to substitute the role of conventional cues in instilling cellular behaviors in muscular dystrophies. Collectively, these data support the notion that lamin A is essential for proper cellular mechanotransduction from extracellular environment to the genome and impairment of the muscle cell differentiation in the pathogenic mechanism for lamin A associated muscular dystrophy.

Assessing bias in personal exposure estimates when indoor air quality is ignored: A comparison between GPS-enabled mobile air sensor data and stationary outdoor sensor data

Neglecting indoor air quality in exposure assessments may lead to biased exposure estimates and erroneous conclusions about the health impacts of exposure and environmental health disparities. This study assessed these biases by comparing two types of personal exposure estimates for 100 individuals: one derived from real-time particulate matter (PM2.5) measurements collected both indoors and outdoors using a low-cost portable air monitor (GeoAir2.0) and the other from PurpleAir sensor network data collected exclusively outdoors. The PurpleAir measurement data were used to create smooth air pollution surfaces using geostatistical methods. To obtain mobility-based exposure estimates, both sets of air pollution data were combined with the individuals' GPS tracking data. Paired-sample t-tests were then performed to examine the differences between these two estimates. This study also investigated whether GeoAir2.0- and PurpleAir-based estimates yielded consistent conclusions about gender and economic disparities in exposure by performing Welch's t-tests and ANOVAs and comparing their t-values and F-values. The study revealed significant discrepancies between GeoAir2.0- and PurpleAir-based estimates, with PurpleAir data consistently overestimating exposure (t = 5.94; p < 0.001). It also found that females displayed a higher average exposure than males (15.65 versus. 8.55 μg/m3) according to GeoAir2.0 data (t = 4.654; p = 0.055), potentially due to greater time spent indoors engaging in pollution-generating activities traditionally associated with females, such as cooking. This contrasted with the PurpleAir data, which indicated higher exposure for males (43.78 versus. 46.26 μg/m3) (t = 3.793; p = 0.821). Additionally, GeoAir2.0 data revealed significant economic disparities (F = 7.512; p < 0.002), with lower-income groups experiencing higher exposure—a disparity not captured by PurpleAir data (F = 0.756; p < 0.474). These findings highlight the importance of considering both indoor and outdoor air quality to reduce bias in exposure estimates and more accurately represent environmental disparities.

3D Gamut Morphing for Non-Rectangular Multi-Projector Displays.

In a spatially augmented reality system, multiple projectors are tiled on a complex shaped surface to create a seamless display on it. This has several applications in visualization, gaming, education and entertainment. The main challenges in creating seamless and undistorted imagery on such complex shaped surfaces are geometric registration and color correction. Prior methods that provide solutions for the spatial color variation in multi-projector displays assume rectangular overlap regions across the projectors that is possible only on flat surfaces with extremely constrained projector placement. In this article, we present a novel and fully automated method for removing color variations in a multi-projector display on arbitrary shaped smooth surfaces using a general color gamut morphing algorithm that can handle any arbitrarily shaped overlap between the projectors and assures imperceptible color variations across the display surface.

Effects of spraying parameters and heat treatment temperature on microstructure and properties of single-pass and single-layer cold-sprayed Cu coatings on Al alloy substrate

Exploring the deposition of single-pass and single-layer pure Cu coatings on Al alloy substrate through high-pressure cold spray technology is a crucial endeavor with significant implications for advancing the utilization of such coatings. Regrettably, research in this specific area remains scarce, highlighting the need for further investigation and understanding. This study examined the characteristics of cold-sprayed Cu coatings deposited on a 6061 T6 aluminum alloy substrate under varying gas temperatures and pressures, and explored the effects of subsequent heat treatment on the microstructure and mechanical properties of the Cu coatings. The morphology, phase composition, surface roughness, thickness, porosity, microstructure, shear strength, and microhardness of the cold-sprayed Cu coatings were systematically analyzed. The findings indicated that the spraying parameters had a substantial impact on the properties of the Cu coatings. Specifically, increased gas pressure led to rougher surfaces and lower porosity, whereas higher gas temperature produced smoother surfaces and also reduced porosity. At 800 °C and 4.0 MPa, the Cu coatings exhibited the lowest surface roughness, measuring 8.03 μm. Conversely, at 800 °C and 5.5 MPa, the Cu coatings demonstrated the lowest porosity, at 0.26 %. Moreover, the microstructure analysis showed evidence of dynamic recrystallization in the deposited Cu particles, contributing to enhanced mechanical properties. Following this, the influence of heat treatment on the microstructure and properties of the cold-sprayed Cu coatings was examined. The results demonstrated that annealing at different temperatures induced changes in the interfacial microstructure, with the formation of intermetallic compounds between the Cu coating and Al alloy substrate. This interdiffusion phenomenon led to improved bonding strength and mechanical properties of the Cu coatings, as evidenced by increased shear strength. After undergoing heat treatment at 400 °C, the Cu coatings exhibited the highest shear strength, measuring 49.89 MPa. However, excessive heat treatment temperatures resulted in the formation of cracks and a decrease in mechanical properties.