Planar Surface Research Articles

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 analogues 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 metres 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 do 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.

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.

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.

Proper Orthogonal Decomposition Analysis of Flow Characteristics of Aerostatic Bearings based on Large Eddy Simulation

The driving mechanism of the vibration of aerostatic bearings is still unclear. Although there are several interpretations, none of them is conclusive. The difficulty lies in the complicated information concealed beneath the turbulence flow. To this end, the proper orthogonal decomposition (POD) method was systematically implemented in the aerostatic bearing flow field analysis in the present study, and some new findings have been proposed. First, the accuracy of our large eddy simulation (LES) has been validated through quantitative comparisons with the experimental references in terms of pressure distribution. Then, the mode decomposition has been conducted at a circumferential symmetry plane and bottom surface and the influence of supply pressure has been uncovered. It turns out that the vortices within the recess dominate the flowfield when the supply energy Ps=3atm, which could be recognized as the driving mechanisms of vibrations. The convection and shearing process in the vicinity of the recess inlet becomes intense and corresponding vortices become predominant in the cases of Ps=4atm and 5atm. Eventually, the influences of film thickness have also been discussed when Ps=4atm. Different from the case of h=10μm, the low-frequency vortices near the recess outlet could be detected when the film thickness is increased to 20µm. The control of corresponding flow structures might be helpful for the vibration suppression.

Experimental and Numerical Analysis of Natural Fillers Loaded and E-Glass Reinforced Epoxy Sandwich Composites

Natural fibers play a crucial role in sandwich composites due to their biodegradability, ease of manufacturing, and ability to reduce pollution. The research aims to develop new biodegradable polymer composites using pine tree leaves (PTL) fillers loaded with epoxy through hand layup technique with different wt. % of PTL fillers. The molded composites were characterized to analyze the crystal size and plane orientations, surface morphology, thermal resistance, and presence of elemental compositions in the PTL filler-loaded epoxy composites through X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Energy dispersive analysis (EDX), Differential scanning calorimetry (DSC), and Thermogravimetric analysis (TGA). The 40 wt. % of PTL epoxy composites showed a maximum tensile strength of 32±0. 5 MPa, a compressive strength of 15±0.5 MPa, a flexural strength of 55±0.5 MPa, and a Shore D hardness of 73±0.5 SHN. The mechanical strength of 40 wt.% PTL fillers loaded epoxy composite was enhanced by adding a single and double layer of E-Glass fiber on the bottom and top of the PTL fillers loaded epoxy composite, achieving a maximum tensile strength of 76±0.5 MPa. The 40 wt.% PTL fillers loaded double E-glass fiber on the bottom and top of the PTL fillers loaded epoxy sandwich composite attained the maximum tensile strength of 156±0.5 MPa, compressive strength of 29 ±0.5 MPa, flexural strength of 220 ±0.5 MPa, and Shore D hardness of 79±0.5 SHN. The PTL fillers loaded and reinforced double E-Glass fiber epoxy sandwich composite would be used in low-strength structural applications.

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.

Windage loss characterisation for flywheel energy storage system: Model and experimental validation

In this paper, a windage loss characterisation strategy for Flywheel Energy Storage Systems (FESS) is presented. An effective windage loss modeling in FESS is essential for feasible and competitive design. Unlike generic aerodynamic loss models, FESS require particular attention to their unique characteristics i.e., vacuum, small airgaps, high angular speed, and presence of low friction rotor supports.The proposed model is based on several analytical and semi-empirical windage loss solutions for cylindrical and planar surface interactions, harmonised to manage the transition between laminar and turbulent flows. Also, the model is enriched by introducing corrections for rarefied gasses, using kinetic gas theory formulation. Therefore, it is possible the reduce the windage overestimation occurring with Navier–Stokes equation solutions for laminar flow. The model is compared to case studies from the literature featuring different boundary and operating conditions, to check consistency of all the harmonised models. A dedicated experimental test-rig is developed to validate the corrections to the model for rarefied gas at different vacuum levels. Then, a non-invasive characterisation approach for FESS windage losses in self-discharge phase is proposed and validated on the test-rig.

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.

Preparation of oil-in-water type Pickering emulsions stabilized by partially deacetylated nanochitin and pH-triggered drug release

Partially deacetylated nanochitin (DAcNC) exhibits amphiphilicity owing to the hydrophilic protonated amino groups and hydrophobic surface planes of DAcNC. Although DAcNCs possess emulsifying abilities, their role and versatility as emulsifiers remain unclear. In this study, we investigated oil-in-water (O/W) type Pickering emulsions stabilized with DAcNCs. Stable emulsions were formed using a variety of oils such as vegetable oils, decane, and ether oils. Measurements of the interfacial tension and adsorption of DAcNC showed that formation of tolerant interfacial films stabilized the emulsions. Furthermore, the pH-triggered release of ibuprofen, an antipyretic drug, was demonstrated using the emulsion. Enhanced ibuprofen release was observed upon increasing the pH from 2.0 to 6.0. This phenomenon can be attributed to the deprotonation of ammonium moieties on the DAcNC, which induced the desorption of DAcNC from oil/water interfaces. The DAcNC emulsion can be useful for the oral administration of ibuprofen as an antipyretic agent, facilitating intestinal release.

Design and development of solar parabolic concentrator, closed-loop pressurized hot water for a household baking system – For the case of injera baking in Ethiopia

A laboratory setup with two axis of manual sun-tracking was designed and built. To get the predicted values for a solar injera stove, a 20-min heating time to prepare it for baking, 3.1 kWh power in the first hour, and 5.8 kWh (with only an 87 percent increase) in the second hour were acquired to bake 9 and 28 injera using electric injera stove, respectively. The temperature distribution on the clay surface was the range of 180 °C–220 °C. Solar injera baking stove was designed and built using the average energy required to bake one injera from an electrical injera stove. The laboratory setup was put to the test, temperatures at the receiver's surface ranging from 315 to 318 °C and an average solar radiation of 1000 W/m2 was obtained on the first test. The injera stove inlet reached a maximum temperature of 180.92 °C with a pressure of 14.5 bars during a pressurized hot water production and circulation test (load test). The surface temperature of the solar injera stove clay plate reached a maximum of 62.69 °C. Temperature of more than 60 °C was maintained on the surface of the solar injera stove plate for nearly 2 h.

Alkali-fluoride-salt-accelerated oxidation behavior of graphite under air atmosphere

Air ingress accident scenarios may result in the oxidation of graphite matrix materials and cause serious safety problems in molten salt reactor. However, the oxidation behavior of the molten-salt-infiltrated graphite remains elusive. In this study, the effect of alkali fluoride salts (LiF, NaF, KF and ternary salt FLiNaK) on the oxidation behavior of graphite powder under air atmosphere was investigated. Thermogravimetric analysis and oxidation tests manifest that the initial oxidation temperature of the graphite is reduced from 720 °C to 510–610 °C, because of the presence of the alkali fluoride salts. The catalytic oxidation effect follows the order of KF > NaF > LiF. Careful characterizations reveal that the pristine graphite is mainly oxidized at the graphite edges, while salt-infiltrated graphite is mainly damaged at the graphitic basal planes. Density functional theory calculations suggest that the doping of alkali metal atoms does not change the physical adsorption feature of the oxygen molecule on the graphite plane surface, but increases its adsorption energy to facilitate the graphite oxidation reactions.

1D analytic and numerical analysis of thin film heat transfer gauges and infra-red cameras in non-planar applications

The impulse response method is widely used for heat transfer analysis in turbomachinery applications. Traditionally, the 1D method assumes a: linear time invariant, isotropic, semi-infinite block with planar surfaces and does not accurately model the true geometric behaviour. This paper evaluates the error introduced by the planar assumption and outlines the required modifications for accurate freeform surface analysis. Adapted cylindrical basis functions are defined for the impulse response method and used to evaluate the impact of the 1D planar assumption. The analytic solutions for both convex and concave surfaces are presented. A penta-diagonal algorithm, for a modified numerical Crank-Nicolson scheme, is also evaluated for fast stable implementation of curved geometry simulation. The scheme shows comparable performance to the impulse response, whilst removing the requirement for linear time invariance. The new methods are demonstrated in the case of aerothermal analysis for heat transfer in a turbine nozzle guide vane. A 3D ANSYS simulation is used as a benchmark and further highlights the importance of the curvature effects. The methods are extended using curvature mapping for infra-red camera data, enabling direct 3D thermal simulation or the fast calculation of freeform curvature. This paper defines the methodology to analyse heat transfer measurements on non-planar geometry.

Recycling of Waste Plastic PET on Asphalt Concrete (AC) by Using Application of Response Surface Methodology: Effect of PET on AC Formulated by Duriez Model

The wet recycling process of plastic waste was used to design a composite material (asphalt concrete) following the Duriez method. This process aims to improve the rheological performance of asphalt concrete by transforming PET on powdery and added to bitumen. To attend this objective, Doehlert' surface plane was used to assess how the asphalt rate, the PET rate and size, and then the aggregate rate affected the stability (wet and dry) and, in turn, the immersion/compression strength index (RI/C), the absorption capacity, the compactness as well as the void that could be filled by the 0/10 AC (asphalt concrete). All quadratic multivariate polynomial models with interactions were obtained and validated in order to optimize the responses. Thus, the physical characterization made it possible to obtain an asphalt concrete with good mechanical characteristics. In addition, it was observed that the selected factors had a different impact on the responses, which are: IR/C; the water absorption capacity, compactness and void filled by the binder by significantly increasing or decreasing them in simple, quadratic and interaction contributions. From the multi-response optimization, the objective was to obtain a composite material (Asphalt-PET-Aggregates) with has the best rheological characteristic, resulted in the following compromise: Bitumen rate 7%, PET 6% of asphalt, PET size 0,5mm; Aggregate content 93%. The simulated optimal values yielded the following responses were: 0.77 RI/C, immersion/compressive strength (Y.<SUB>RI/C</SUB>); 2.9%, absorption capacity (Y.<SUB>WAC</SUB>); 94%, compactness (Y.<SUB>C</SUB>); 71% void filled by asphalt (Y.<SUB>VFA</SUB>)