Planar Surface Research Articles

Enhancing the Kinetics of Vapor-based Polymerization by Pulsed Filament Approach.

Initiated chemical vapor deposition is a versatile technique for synthesizing conformal polymer films on both planar and porous surfaces. It can retain functional groups and avoid undesired cross-linking. However, there is still room for enhancing its performance without altering the feed parameters. Here, we investigate a pulsed iCVD approach to improve the deposition process, achieved by switching on and off the resistively heated filament periodically. By strategically switching off the filament, a shortage of thermally activated primary radicals was created, which allowed uninterrupted chain propagation with fewer termination reactions and potentially increased monomer conversion rates. This has caused significantly faster deposition kinetics with a higher molecular weight and longer chain length for poly(glycidyl methacrylate) compared to continuous deposition. Spectra analyses confirmed that the functionality and stoichiometry ratios remained intact throughout the pulsed deposition process. The pulsed iCVD method is therefore a competitive and sustainable tool, demonstrating fast deposition kinetics and a well-preserved functionality.

How large is the collapsed area of ground collapse induced by tunnelling

ABSTRACT Ground collapse has frequently been reported in recent years, which poses a great threat to the safety of human beings and property. This study aims to determine the collapsing diameter and volume of tunnelling-induced ground collapse by analytical method. Firstly, assuming that the surface of collapsed block is sliding along a planar surface, and the sliding area is derived based on the limit equilibrium method. Then, the collapse volume is derived by combining with the equation of the collapse trajectory. Lastly, the proposed method is verified by a physical modelling test. The results show that (i) as the unit weight of soil, buried-depth and the radius of tunnel increase, the influencing diameter and collapse volume gradually increase; (ii) with the increase in the cohesion and friction angle of the soil, the influencing diameter and collapse volume gradually decrease. Dongquan Tunnel is taken as a case study, the influencing diameter of ground by using the proposed approach is compared with the one in practical engineering. This study provides a theoretical guideline to mark the collapse warning lines by the potential ground collapse area, which is induced by excavation of shallow-buried tunnels or underground structures.

Self-cleaning and anti-corrosion superhydrophobic coatings of PA-TiO2@SiO2 copolymerized hetero compound

Inspired by leaf lotus effect, superhydrophobic surfaces have developed rapidly in recent years. In this paper, anatase nano TiO2 with particles size of about 70 nm was successfully loaded on the surface of SiO2 by sol-gel method. SiO2 and TiO2 were chemically bonded by Ti-O-Si and constructed a certain micro- and nano-composite structure. After superhydrophobic composite PA-TiO2@SiO2 was obtained by copolymerizing with acrylate and other monomers. The coating was prepared by drop coating plus spraying coating on glass substrates with water contact angles >160° and excellent self-cleaning properties, which could maintain the performance of the superhydrophobic coating by immersion in acidic solutions or water for 2 days. Meanwhile, the coating on the surface of the glass plate at −20 °C significantly delayed the freezing time of the ice. The rough structure of the surface and the presence of fluorine-containing hydrophobic groups gave the superhydrophobic coating an advantage over acrylate polymers in reducing the corrosion rate of steel surfaces.

Dynamics of particle aggregation in dewetting films of complex liquids

We consider the dynamic wetting and dewetting processes of films and droplets of complex liquids on planar surfaces, focusing on the case of colloidal suspensions, where the particle interactions can be sufficiently attractive to cause agglomeration of the colloids within the film. This leads to an interesting array of dynamic behaviours within the liquid and of the liquid–air interface. Incorporating concepts from thermodynamics and using the thin-film approximation, we construct a model consisting of a pair of coupled partial differential equations that represent the evolution of the liquid film and the effective colloidal height profiles. We determine the relevant phase behaviour of the uniform system, including finding associated binodal and spinodal curves, helping to uncover how the emerging behaviour depends on the particle interactions. Performing a linear stability analysis of our system enables us to identify parameter regimes where agglomerates form, which we independently confirm through numerical simulations and continuation of steady states, to construct bifurcation diagrams. We obtain various dynamics such as uniform colloidal profiles in an unstable situation evolving into agglomerates and thus elucidate the interplay between dewetting and particle aggregation in complex liquids on surfaces.

A temperature field model based on energy flow analysis of wet clutch sliding interface

A fluid-solid convective heat transfer model is constructed according to the velocity distributed calculation of lubricant in clutch groove cavity. Considering the characteristics of circumferential alternation of heat dissipation and generation area on separator plate surface,the effective energy flow characterization equations of convective hear transfer and heat generation at sliding interface are established. The non-heat source temperature field is proposed by effective convective heat transfer and heat conduction. Following the target constraint of continuous contact temperature, the temperature field change is solved during actual dynamic heat flux partition period. The tests with different intensity of heat generation and dissipation are designed, which indicates the reliability of model. The research provides a new method for the temperature field calculation of clutch.

Improved bacterial elimination in wastewater through electrocoagulation: hydrogen generation, adsorption of colloidal bacteria-flocks, and electric field bactericidal action

ABSTRACT Electrocoagulation (EC) has emerged as a promising method for wastewater treatment, offering efficient removal of various contaminants, including bacteria. This study investigates the mechanisms underlying bacterial removal in EC processes, mainly the hydrogen-mediated foam, the effect of operational parameters, including initial pH, current density, and reaction time, and evaluates the associated energy consumption. The EC reactor employed aluminum electrodes and operated at a current intensity of 3.0 A. It demonstrated a notable bacterial removal efficiency, with 120.102 UFC ml−1 of mesophyll floral aerobic bacteria removed through colloid bacteria-flocs precipitation, 440.102 UFC ml−1 via bacterial-bulls flotation from foam, and 117.102 UFC ml−1 through attraction at the electrodes’ plate surface. We found that the EC process leads to the formation of aluminum hydroxide and ferrous hydroxide precipitates, which adsorb bacteria and facilitate their removal from the wastewater via electrostatic forces with an energy consumption of 45 kWh/m3. Overall, this research provides valuable insights into the mechanisms governing bacterial removal in EC and highlights the importance of energy consumption analysis for optimizing wastewater treatment processes.

Structure and performance of N-doped amorphous carbon films (a-C: N) on stainless steel surfaces for bipolar plates in proton exchange membrane fuel cells

Stainless steel bipolar plates (BPPs) are anticipated to supersede traditional graphite BPPs in proton exchange membrane fuel cells (PEMFCs) owing to their superior machinability, enhanced mechanical strength, and cost-effectiveness. Nevertheless, stainless steel BPPs are susceptible to corrosion and dissolution in acidic environments over extended periods, leading to the formation of a passivation film that diminishes conductivity. In this study, amorphous carbon (a-C) films with varying N doping contents were deposited onto 304L stainless steel foil using the cathodic arc ion plating technique. This was achieved by manipulating the N2 flow rate. The research investigated the impact of N doping on the microstructure, corrosion resistance, interfacial contact resistance (ICR), and hydrophobicity of the a-C films on stainless steel surfaces. The findings reveal that the various a-C films significantly enhance the performance of 304L stainless steel under simulated PEMFCs operating conditions. While N-doped a-C (a-C: N) films are advantageous for reducing ICR, incorporating N results in a decrease in C-sp3 content and density, ultimately leading to a decrease in the corrosion resistance of films. Additionally, the hydrophobicity of the a-C films diminishes with increasing N content. Consequently, N doping is not conducive to improving the overall performance of a-C films on the surface of 304L stainless steel bipolar plates under simulated PEMFCs operating conditions.

Research on reversible bonding of microfluidic chips based on stretch release adhesive strips

AbstractThe reversible bonding of microfluidic chips has been developing rapidly with the requirement of reusable microfluidic devices or the need to obtain the samples inside the chip. Traditional bonding methods for polymer‐based microfluidics, e.g., thermal bonding, permanently attach the substrate and cover plate. Sometimes, once the chip flow channel is blocked, it is difficult to clean and affect the reusability of the chip. This study proposes a new reversible bonding method for poly (methyl methacrylate) (PMMA) microfluidic chips with the help of stretch release adhesive strips. The designed microchannels were fabricated on the surface of PMMA plates using CO2 laser irradiation. Then, stretch release adhesive strips were used as an intermediate layer between the substrate (with microchannels) and another flat PMMA/PS/PC plate to seal the microchannel. The assembled chip sets were bonded at room temperature with bonding strength comparable with other permanent bonding methods. Experimental results show that simply pulling the adhesive layer by applying a shear force can easily detach the intermediate adhesive layer from both the substrate and cover plate to separate the bonded chipset. The proposed reversible bonding method is simple, rapid and has low residue and high bonding strength. Bacterial culture experiments were also conducted to verify the biocompatibility of the proposed bonding method. The proposed reversible bonding technique can be used for polymer‐based microfluidic devices that require sample recovery or chip reuse.Highlights The stretch release adhesive strip can provide high bond strength. It allows easy peeling for reversible bonding. It bonds at room temperature with simple operation. It has good transparency for easy observation of experiments. It has good biocompatibility.

XPS Depth-Profiling Studies of Chlorophyll Binding to Poly(cysteine methacrylate) Scaffolds in Pigment-Polymer Antenna Complexes Using a Gas Cluster Ion Source.

X-ray photoelectron spectroscopy (XPS) depth-profiling with an argon gas cluster ion source (GCIS) was used to characterize the spatial distribution of chlorophyll a (Chl) within a poly(cysteine methacrylate) (PCysMA) brush grown by surface-initiated atom-transfer radical polymerization (ATRP) from a planar surface. The organization of Chl is controlled by adjusting the brush grafting density and polymerization time. For dense brushes, the C, N, S elemental composition remains constant throughout the 36 nm brush layer until the underlying gold substrate is approached. However, for either reduced density brushes (mean thickness ∼20 nm) or mushrooms grown with reduced grafting densities (mean thickness 6-9 nm), elemental intensities decrease continuously throughout the brush layer, because photoelectrons are less strongly attenuated for such systems. For all brushes, the fraction of positively charged nitrogen atoms (N+/N0) decreases with increasing depth. Chl binding causes a marked reduction in N+/N0 within the brushes and produces a new feature at 398.1 eV in the N1s core-line spectrum assigned to tetrapyrrole ring nitrogen atoms coordinated to Zn2+. For all grafting densities, the N/S atomic ratio remains approximately constant as a function of brush depth, which indicates a uniform distribution of Chl throughout the brush layer. However, a larger fraction of repeat units bound to Chl is observed at lower grafting densities, reflecting a progressive reduction in steric congestion that enables more uniform distribution of the bulky Chl units throughout the brush layer. In summary, XPS depth-profiling using a GCIS is a powerful tool for characterization of these complex materials.

Surface Morphology of Various Matrixes with Zirconium Oxide Coatings Synthetized by Alternating Pulsing of Zirconium(IV) <i>tert</i>-Butoxide and Water Vapors Treatment of the Surface

Zirconium oxide coatings of various thicknesses were synthesized on the surface of plates of monocrystalline silicon and borosilicate glass by alternating pulsing of zirconium(IV) tert-butoxide and water vapors treatment. The effect of the matrix type and the coating thickness on surface morphology of the samples was investigated using atomic force microscopy. The concentrations of zirconium in the synthesis products were determined by X-ray spectral microanalysis and the growth constant of the zirconium oxide film on silicon was evaluated. Assumptions are made about the influence of the type of the matrix on the structure of the surface of the zirconium oxide layer.

Effect of High-Speed Longitudinal Ultrasonic Vibration-Assisted Milling on Tribological Characteristics of a Plane Surface

Effect of High-Speed Longitudinal Ultrasonic Vibration-Assisted Milling on Tribological Characteristics of a Plane Surface

Three-Dimensional-Printed Modular Titanium Alloy Plates for Osteosynthesis of the Jawbone.

The titanium-aluminum-vanadium alloy (Ti-6Al-4V) is frequently used in implantology due to its biocompatibility. The use of 3D printing enables the mechanical modification of implant structures and the adaptation of their shape to the specific needs of individual patients. The titanium alloy plates were designed using the 3D CAD method and printed using a 3D SLM printer. Qualitative tests were performed on the material surface using a microcomputed tomography scanner. The cytotoxicity of the modular titanium plates was investigated using the MTT assay on the L929 cell line and in direct contact with Balb/3T3 cells. Cell adhesion to the material surface was evaluated with hFOB1.19 human osteoblasts. Microbial biofilm formation was investigated on strains of Lactobacillus rhamnosus, Staphylococcus epidermidis, Streptococcus mutans and Candida albicans using the TTC test and scanning electron microscopy (SEM). The surface analysis showed the hydrophobic nature of the implant. The study showed that the titanium plates had no cytotoxic properties. In addition, the material surface showed favorable properties for osteoblast adhesion. Among the microorganisms tested, the strains of S. mutans and S. epidermidis showed the highest adhesion capacity to the plate surface, while the fungus C. albicans showed the lowest adhesion capacity. The manufactured modular plates have properties that are advantageous for the implantation and reduction in selected forms of microbial biofilm. Three-dimensional-printed modular titanium plates were investigated in this study and revealed the potential clinical application of this type of materials, regarding lack of cytotoxicity, high adhesion properties for osteoblasts and reduction in biofilm formation. The 3D CAD method allows us to personalise the shape of implants for individual patients.

Analysis on axial force characteristics of variable valve and variable speed adjustment of centrifugal pump

In order to study the evolution mechanism of axial force characteristics of centrifugal pump in the transient process of variable working conditions, the IS80-65-160 centrifugal pump is taken as the research object, and four flow operating points of centrifugal pump 1.0Qr, 0.8Qr, 0.6Qr, and 0.4Qr are selected. Non-constant numerical simulation is carried out, and on the basis that the numerical calculation results of the external characteristics are basically consistent with the experimental results, the changes of the axial force of the impeller during the flow reduction process of the variable valve adjustment and the variable speed adjustment of the centrifugal pump are studied, respectively. The results show that as the flow rate decreases, the force of the variable valve regulating impeller cover plate increases, and the force of the variable speed regulating cover plate decreases. Under the two adjustment methods, the axial force on the pressure surface of the blade becomes smaller, the axial force on the suction surface of the blade is basically unchanged, and the pulsation coefficient of the impeller axial force increases first and then decreases. The axial force pulsation coefficient reaches the maximum value in the variable valve adjustment condition of 0.8Qr and the variable speed adjustment condition of 0.6Qr, respectively, and the axial force on the outer wall of impeller cover plate has the greatest influence on the main frequency axial force ripple coefficient; the axial force acting on the outer wall surface of the front cover plate of the impeller and the inner wall surface of the front and rear cover plates increases with the increase in the radius, The axial force acting on the outer wall surface of the rear cover plate of the impeller has axisymmetrical properties. This study revealed the evolution mechanism of the axial force characteristics of the centrifugal pump impeller during the transient process of variable working conditions, and the research results can provide a reference for improving the stable operation of the centrifugal pump.

Firmgrounds and hardgrounds in the Coniacian carbonate platform of the Iberian basin: Origin and model for development of omission surfaces in tidal environments

Distinctive erosional and omission surfaces occur at several stratigraphic levels in the tidal carbonates of the 3rd-order Coniacian sequence (Iberian Basin). They are ancient analogs of omission surfaces developed on lithified carbonates in subaerial and coastal settings. Omission surfaces consist of (i) firmground Glossifungites ichnofacies (Balanoglossites-Thalassinoides); and (ii) hardground Trypanites ichnofacies (scalloped and planar surfaces and Gastrochaenolites-Entobia surfaces). Firmgrounds are also related to erosion or ferruginous crusts. Hardground surfaces are related to bioerosion, dissolution and physical erosion. Grain size and textural features in Balanoglossites and Thalassinoides firmground surfaces are essentially the same, suggesting that even bathymetry could be similar. Several stages in hardgrounds consist of different, scalloped or planar surfaces related to bioerosion, dissolution and physical erosion. Gastrochaenolites-Entobia borers represent a major change in the trace fossil associations and imply different processes in their origin, being originated at slightly different depths with Gastrochaenolites representing shallower environments. The studied field sections display a cyclicity on the scale of meters that tentatively reflects the presence of 4th-order parasequence sets. Two kinds of sedimentary discontinuities have been used for correlation: omission surfaces and ferruginous crusts representing regional sea level falls and rises. Part of the described surfaces does not appear to have been previously recognized in older carbonate deposits. Their common presence of similar surfaces along modern coasts and in karst terrains, as well as their abundance in the Coniacian sequence, suggests that they might also be abundant in the geologic record in other sedimentary basins for defining palaeoshorelines.

Effects of pre-deformation mode on non-homogeneity of plastic deformation and mechanical properties in Al–Cu–Mg–Ag alloy

The influence of a pre-deformation mode during the thermomechanical treatment of an A2139 Al alloy plate on the non-homogeneity of plastic deformation and mechanical properties was investigated. Two pre-deformation modes were selected: cold stretching (CS) and cold rolling (CR). The CS mode demonstrated a uniform equivalent strain in the thickness direction. However, a higher overall equivalent strain was observed in the CR mode, with the equivalent strain being higher on the surface than at the center of the plate. When a pre-deformation of 7% was applied, surface defects, such as orange peels, occurred on the plate surface in the CS mode. In contrast, in the CR mode, a clean surface was obtained. Therefore, to obtain a clean plate surface, pre-deformation through CR is more effective than that through CS. With the application of pre-deformation, hardness and strength increased significantly without a decrease in elongation, and the time required to reach peak aging could be shortened significantly. The CR mode exhibited greater improvements in terms of hardness and strength compared to the CS mode. However, in terms of toughness, the CS mode showed a greater improvement than the CR mode. Therefore, to achieve both high strength and a clean plate surface with increasing pre-deformation, utilizing the CR mode is more effective. In the CR mode, despite a significant reduction in the residual stress after artificial aging, a weak tensile residual stress remained on the surface. By contrast, in the CS mode, most of the residual stress was removed after artificial aging.

Minimizing Recess of Cu Pad on Hybrid Bonding with SiCN via Non-selective Chemical Mechanical Polishing and Post-cleaning Steps

Hybrid bonding has become a promising approach to realizing fine pitch interconnection via bonding for both the wafer level and die level. The morphology and cleanliness of the bonding surface are critical to ensure a high yield. Therefore, surface planarization by chemical mechanical polishing (CMP) is considered a key process. The recess on the Cu pad must be controlled to be less than 5 nm by adjusting the removal rate between the Cu, the barrier layer, and the bonding dielectric layer. Conventionally, SiO2 has served as the bonding dielectric. However, SiCN is considered a promising dielectric because of its high bonding strength, suppression of voids, and ability to function as a Cu diffusion barrier. Here, we investigated simultaneous Cu, barrier, and SiCN CMP for hybrid bonding. Post-CMP processes such as cleaning and activation were also assessed. The results revealed that the removal rate of the three materials could be adjusted by dilution of the slurry and oxidizer. Lower selectivity was achieved at a certain dilution rate in an alkaline barrier slurry. Plasma activation revealed that the Cu passivation layer formed during cleaning was removed. Therefore, residues from CMP and post-CMP processes did not affect Cu prior to the hybrid bonding.

Effect of SiO2 concentration on the mechanical and anticorrosive properties of the hybrid PMMA/SiO2 coating synthesized in situ by sol-gel process.

Abstract Anti-corrosive evaluation of a hybrid polymethylmethacrylate (PMMA) with silica particles (SiO2) is presented, the hybrid (PMMA-SiO2) was synthetized in situ by sol-gel process. The SiO2 particles were embedded into to matrix PMMA at different concentrations. The hybrid structure of the coatings was characterized and observed with Fourier Transform Infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The deposition of the hybrid in aluminum 7075-T6 (Al7075) substrates was made with the blade coating technique, measuring wet and dry film thickness. For the preparation of the hybrid, PMMA was used without any type of curing, which allowed us to save resources. All tests were performed according to American Society for Testing and Materials (ASTM international) standards. The incorporation of SiO2 to concentrations significantly improved the mechanical and anti-corrosive results. PMMA-SiO2 coating, once deposited on the surface of Al7075 plates, has been tested inside a salt fog chamber (CNS) operated under accelerated conditions. They were improved up to 920 h its corrosion resistance. The abrasion tests had an increase of 50%, its hardness up to 4H and the wear index improved by 50% compared with the hybrids with minor SiO2 concentration, which shows that a higher concentration of SiO2 particles has a higher performance of the coating.

Embedding of Neutrosophic Graphs on Topological Surfaces

Background: A planar graph (PG) is a graph with no intersecting edges. Particular to both crisp and neutrosophic graphs (NG) is the planar graph, in contrast to crisp planar graphs. NPGs allow for the intersection of neutrosophic edge NEs, since the value of planarity in these graphs is the degree of planarity of the intersected NEs. The NPGs are often represented on a flat surface. Materials and Methods: This study discusses how to embed NGs on surfaces such as spheres and m-toruses by defining the degree of intersection of the neutrosophic edges of NGs with finding the faces on the given graph structures using Euler's theorems. Here, the proofs of Euler's theorems help us find, given the total NFV of G, the interval containing that value. Result: As result of this work obtained that for any two isomorphic planer graphs, they have the same planarity value. For any neutrosophic planer graph with f = (1,1,1) can be embedded in the plane if it can be embedded in the sphere and according to NPGs, for planar and spherical surfaces, equivalent theorems to Euler's formula are proved and shown. Conclusion: It concludes that by using neutrosophic sets and crisp graphs to construct neutrosophic graphs with the benefit of Euler’s theorem, it can provide the concept of embedding neutrosophic graphs in different topological surfaces such as a plane, sphere, and m-torus.

Measurement of wing motion, deformation, and inertial forces of a biomimetic butterfly.

This paper introduces a method for measuring wing motion, deformation, and inertial forces in bio-inspired aircraft research using a camera motion capture system. The method involves placing markers on the wing surface and fitting rigid planes to determine the wing's spatial axis. This allows for describing the wing's rigid motion and obtaining deformation characteristics, such as deflection, twist angle, and gap distance of the forewing and hindwing. An image-based method is proposed for determining wing mass distribution, mass blocks, and mass points for inertial force measurement. The study addresses wing motion, deformation, and inertial force measurement in a real butterfly-like flapping wing vehicle and demonstrates the effectiveness of the approach. The results reveal that inertial forces play a negligible role in the generation of lift peaks and contribute minimal lift during the entire flapping cycle. Furthermore, a transitional phase between downstroke and upstroke is found in flexible wing motion, which has high lift production. This measurement approach offers a rapid and effective solution to experimental challenges in bio-inspired aircraft design and optimization.

Nail Alterations From Musical Instruments: Insights for Dermatologists Treating Musicians.

Long-term practice and performance with a musical instrument predispose musicians to several skin conditions and nail disorders. We conducted a comprehensive literature search of the PubMed, Scopus, and Google Scholar databases for articles on nail alterations in musicians. Complications were divided into modifications of the nail surface and nail plate, soft-tissue abnormalities, and periungual tissue and distal pulp disorders. Health care professionals should be aware of these various modifications related to the use of musical instruments and provide preventive measures.