Surface Characterization Research Articles

An innovative aluminium foil electrode modified with Al nanoparticles and EDTA for lead detection in biological samples

This study presents a novel Aluminium foil-based electrode characterized by its affordability, flexibility, and ease of modification with carboxylic moiety-containing organic molecules. Upon foil modification with Aluminium nanoparticles and EDTA (AlNP-EDTA/AlE), the modified electrode exhibits remarkable activity in the oxidation of lead at potentials around −0.4 V. The lead signal is derived from the oxidation of lead deposited on the electrode surface using anodic stripping voltammetry (ASV). The addition of EDTA to AlNP/AlE increased the anodic peak current of lead by more than 500 %. The surface characterization of the electrode was performed by scanning electron microscopy (SEM) and infrared spectroscopy (IR), while its electroactive properties were evaluated by cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS). Optimal operating parameters include pH 2.1, square-wave voltammetry (SWV) with an accumulation time of 60 s and an accumulation potential of −0.8 V. A low detection limit of 0.20 µmol/L and a relative standard deviation (RSD) of 3.0 % were achieved using five different electrodes. The effectiveness of AlNP-EDTA/AlE was further demonstrated with consistent results in biological samples spiked with Pb.

MOF-templated synthesis of ZnxCo1-xS nanocubes for efficient degradation of dyes by peroxymonosulfate activation

In this work, ZnxCo1-xS nanocubes were synthesized and templated by bimetallic metal organic framework (MOF), which showed highly efficient degradation of Methylene Blue (MB) by peroxymonosulfate (PMS) activation. The structure and surface characterization were subsequently analyzed by FESEM, XRD, BET and XPS, identifying the successful synthesis of Zn0.76Co0.24S. The best properties were obtained when equal mass of TAA and CoZn-ZIFs were employed, the three dyes, MB, RhB, and MO, reached more than 99.9% degradation efficiency within 10 min after activation by PMS. The catalytic mechanism was further elucidated by ESR tests and radical trapping experiments. Abundant S vacancies were discovered in Zn0.76Co0.24S nanocubes, which would highly promote the catalytic activities. It was proved that S vacancies, 1O2 and ⋅O2− played important roles in the PMS activated degradation process. Above all, this study provided a new strategy to synthesize MOF-templated ZnxCo1-xS with optimized TAA dosage, which showed promising application on water treatment aspects.

Surface characterization of barium(II)–selective potentiometric sensor based on a newly synthesized hydrazone derivative molecule

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Evaluating the catalytic effect of pyrite on thiourea leaching of gold in the absence and presence of citrate

With the depletion of high-quality ore, the extraction of gold from refractory gold ores/concentrates is a promising endeavor. Pyrite is an important gold-bearing sulfide mineral. It is of great significance to study its influence on gold leaching to realize the maximum utilization of refractory sulfide gold ores/concentrates. In this paper, the effect of pyrite on thiourea leaching of gold was investigated through leaching experiment, surface characterization and density functional theory (DFT) calculation. Results showed that the presence of pyrite sharply decreased both gold dissolution and thiourea stability, and its adverse effect of pyrite is likely that pyrite catalyzes the oxidation of thiourea by Fe3+, resulting in the high thiourea consumption, which deteriorates the gold dissolution. The catalytic mechanism is believed to be that thiourea firstly adsorbs on the pyrite surface, and then electrons transfer from thiourea to the oxidant of Fe3+ through the conduction band of pyrite. Citrate was used as an additive to improve the thiourea stability and gold dissolution, and its mechanism was proposed as follows: citrate weakens the interaction between Fe3+ and thiourea by complexing with Fe3+, and competes with thiourea to adsorb on the surface of pyrite, reducing the adsorption of thiourea. Furthermore, the formation of Fe-citrate complexes, as terminal electron acceptor, has a lower oxidation capacity than Fe3+, thus relieving the catalytic effect of pyrite on thiourea oxidation by Fe3+.

Oxidation Mechanism and Surface Characterization of Pyrolytic Graphite in Simulated Air for Pyrochemical Reprocessing Application

Accidental air ingress into the containment chamber of pyrochemical reprocessing of spent nuclear fuels can cause severe oxidation of graphite components. Pyrolytic graphite (PyG) coating on conventional high-density graphite (HDG) is proposed for protection against oxidation, molten salt, and molten metal corrosion. The aim of the present study is to evaluate the thermal stability and kinetic parameters and propose a suitable oxidation mechanism of PyG under simulated air using thermogravimetry analysis (TGA). In dynamic oxidation, a linear increase in the oxidation onset, peak, and burnout temperature is observed for PyG synthesized at increasing pyrolysis temperature from 1200 to 2400°C except for 1400°C. The isothermal oxidation study showed a similar trend i.e., a decrease in the linear oxidation rate constant value for any given isotherm with increasing pyrolysis. The Arrhenius plot showed two-stage oxidation regimes operating between 600 to 1000°C. In regime-I, between 600 to ∼800°C controlled by surface chemical reaction kinetics, the activation energy is measured between 100-200 kJ.mol−1. The graphite-oxygen reaction initiates and propagates preferentially along the prismatic planes at the sample edges, where the dangling bonds of stacked graphite layer structures are exposed. In regime-II operating above ∼800°C, the surface reaction rate is infinitely faster, and the diffusional mass transport becomes a rate-limiting factor. In this regime, the graphite-oxygen initiates by pore formation on defective reactive sites on the bulk surface and propagates by pore-widening and pore-coalescence mechanism. The observed differences in the oxidation rates for different pyrolysis PyG attributed to its intrinsic material properties are investigated. This work provides new insights into the oxidation mechanism of the PyG during accidental air ingress in a pyrochemical reprocessing plant.

A methodology for the 3D characterization of surfaces using X-ray computed tomography: Application to additively manufactured parts

Many studies highlight the significance of three-dimensional surface topography characterization in assessing its effect on the mechanical or functional properties of materials. This is especially obvious for parts made by additive manufacturing (AM), known for their complex shape and surface topographies. However, a vast majority of 3D characterizations have constraints regarding the macroscopic geometry of the parts they can probe. At the microscale, they are also unable to account for hidden surface features, e.g. notches hidden by unmelted powder particles. Even with the use of X-ray Computed Tomography (XCT) - a tool with the potential to circumvent these issues -data is often reduced to 2D or 2.5D formats for easier analysis, but this leads to a loss of information. This underscores the need for XCT data post-treatment tools to perform thorough 3D surface characterizations. Herein, we introduce a methodology for local roughness and curvature characterization of surfaces of complex shapes using XCT. This method has been designed to be user-friendly, especially for those without extensive data analysis expertise. It provides a comprehensive 3D characterization and efficiently tackles the issues caused by hidden features. After a detailed description of our methodology, we give a first illustrative example based on architected structures fabricated by Electron Powder Bed Fusion (E-PBF). By integrating roughness and curvature metrics, we also derive a parameter indicative of the stress concentrations caused by surface irregularities.

Enhancing the angiogenesis and osteogenesis of low elastic modulus Ti-Nb-Zr-Sn alloy surface through grafting growth factors-containing gelatin nanoparticles

The study aimed to apply a multiple surface modification for low elastic modulus Ti-24 % Nb-4 % Zr-8 % Sn (Ti2448) alloy, to enhance its biological properties for bone implant applications. We employed a combined sandblasting/acid etching/alkaline etching process to modify the Ti2448 alloy surfaces with mixed nano/submicron/micron-scaled pits and super wettability. We prepared gelatin nanoparticles (GNPs) loaded with growth factors: vascular endothelial growth factor/platelet-derived growth factor (VEGF/PDGF) and/or bone morphogenetic protein-2 (BMP-2). The growth factors-containing GNPs were then sequentially grafted onto the surface-modified Ti2448 alloy in a layered (single layer: BMP-2 or VEGF/PDGF; double layer: inner BMP-2 and outer VEGF/PDGF) or mixed BMP-2/VEGF/PDGF manner. Surface characterizations, including morphology, roughness, surface energy, and cytotoxicity, of Ti2448 alloy were analyzed. For biological response, we investigated the tube formation ability of human umbilical vein endothelial cells (HUVECs) and the cell responses (adhesion, proliferation, and mineralization) of human bone marrow mesenchymal stem cells (hMSCs). The results demonstrated the successful preparation of GNPs with 200∼300 nm particle size and their successful loading with the growth factors using natural crosslinker genipin. The growth factor-containing GNPs were effectively grafted onto the surface-modified hydrophilic Ti2448 alloy without significantly reducing its wettability (water contact angle remained below 40°). The results of the study showed that the GNPs-grafted Ti2448 alloy surfaces, with the GNPs loaded with VEGF/PDGF and/or BMP-2, exhibited enhanced biological properties. The GNPs-grafted surfaces were found to be non-toxic and capable of promoting tube formation of HUVECs, particularly when single VEGF/PDGF layer or double (inner BMP-2/ outer VEGF/PDGF) layer was loaded on GNPs (enhancing the cumulative tube length approximately 1.4 times that of no GNPs-grafted surfaces). Moreover, the GNPs-grafted surfaces enhanced the adhesion-related proteins and extracellular matrix mineralization of hMSCs, particularly with the loading of single VEGF/PDGF or mixed VEGF/PDGF/BMP-2 on GNPs (enhancing αvβ3 integrin patch number > 3.5 times, vinculin patch number > 2 times, and mineralization approximately 1.4 times). Based on these findings, we concluded that the proposed Ti2448 alloy surfaces, when grafted with VEGF/PDGF- and/or BMP-2-containing GNPs, have the potential for bone implant applications. The surface modifications on the Ti2448 alloy may promote angiogenesis in the early stage of bone repair (through VEGF/PDGF) and osteogenesis in the late stage (through BMP-2), thereby accelerating the overall bone healing process.

Fabrication and characterization of durable superhydrophobic and superoleophobic surfaces on stainless steel mesh substrates

Introduction. This study explores the fabrication of durable superhydrophobic and superoleophobic surfaces on stainless steel mesh, inspired by natural structures like lotus leaves. Achieving superoleophobicity, especially with enhanced durability, is challenging due to the lower surface tension of oils. Methodology. This novel technique involves using Perfluorooctyltriethoxysilane (PFOTES) and silicon dioxide nanoparticles to create re-entrant structures, low surface energy, and high roughness. This cost-effective approach ensures simplicity without requiring expensive equipment. Results. The resulting surfaces exhibit remarkable superoleophobic properties, with hexadecane and soybean oil contact angles reaching 170° and 163.8°, respectively. Scanning electron microscopy confirms successful fabrication, and wear abrasion tests demonstrate mechanical durability, with contact angles remaining high even after cyclic loading and sandpaper abrasion. Conclusion. This study presents a pioneering, cost-effective method for fabricating durable superoleophobic surfaces on stainless steel mesh. These surfaces hold promise for applications in self-cleaning coatings and oil-repellent materials.

Application of a Bio-waste Einkorn (Triticum monococcum L.) Husks Adsorbent for Removal of Metanil Yellow and Methylene Blue from Aqueous Media with Equilibrium, Kinetic, and Thermodynamic Studies

In this study, the activated carbon (TmAC) with a high surface area and appropriate pore distribution was produced from einkorn (Triticum monococcum L.) husks by using ZnCl2 with chemical activation method. The efficiency of the obtained activated carbon on the adsorption of anionic (metanil yellow) and cationic (methylene blue) dyestuffs from aqueous solutions was investigated in more detail. In addition, the surface characterization of activated carbon was performed using thermogravimetric analysis-differential thermal analysis (TGA-DTA), elemental analysis, scanning electron microscopy (SEM) images, Brunauer–Emmett–Teller (BET) specific surface areas, N2 adsorption–desorption isotherms, pore volumes, pore size distributions, and Fourier-transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) spectra. The highest surface area of activated carbon was measured as 1321 m2 g−1 at the carbonization temperature of 500 °C by using impregnation ratio (w/w = 2.0). Batch method was used in adsorption experiments. The parameters affecting the adsorption studies such as adsorbent concentration, initial dye concentration, adsorption time, temperature, and pH were investigated. The adsorption mechanisms of metanil yellow (MY) and methylene blue (MB) on activated carbon were explained by using isotherms (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich), kinetic models (pseudo-first-order and pseudo-second-order), and the thermodynamic parameters (Gibbs free energy, enthalpy, and entropy).Graphical

Structural and surface characterizations of 2D β-In2Se3/3D β-Ga2O3 heterostructures grown on c-Sapphire substrates by molecular beam epitaxy

Integrating two-dimensional (2D) layered materials with wide bandgap β-Ga2O3 has unveiled impressive opportunities for exploring novel physics and device concepts. This study presents the epitaxial growth of 2D β-In2Se3/3D β-Ga2O3 heterostructures on c-Sapphire substrates by plasma-assisted molecular beam epitaxy. Firstly, we employed a temperature-dependent two-step growth process to deposit Ga2O3 and obtained a phase-pure (2¯01)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\overline{2 }01)$$\\end{document} β-Ga2O3 film on c-Sapphire. Interestingly, the in-situ reflective high-energy electron diffraction (RHEED) patterns observed from this heterostructure revealed the in-plane ‘b’ lattice constant of β-Ga2O3 ~ 3.038Å. In the next stage, for the first time, 2D In2Se3 layers were epitaxially realized on 3D β-Ga2O3 under varying substrate temperatures (Tsub) and Se/In flux ratios (RVI/III). The deposited layers exhibited (00l) oriented β-In2Se3 on (2¯01)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\overline{2 }01)$$\\end{document} β-Ga2O3/c-Sapphire with the epitaxial relationship of [112¯0]\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$[11\\overline{2 }0]$$\\end{document} β-In2Se3 || [010] β-Ga2O3 and [101¯0]\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$[10\\overline{1 }0]$$\\end{document} β-In2Se3 || [102] β-Ga2O3 as observed from the RHEED patterns. Also, the in-plane ‘a’ lattice constant of β-In2Se3 was determined to be ~ 4.027Å. The single-phase β-In2Se3 layers with improved structural and surface quality were achieved at a Tsub ~ 280 °C and RVI/III ~ 18. The microstructural and detailed elemental analysis further confirmed the epitaxy of 2D layered β-In2Se3 on 3D β-Ga2O3, a consequence of the quasi-van der Waals epitaxy. Furthermore, the β-Ga2O3 with an optical bandgap (Eg) of ~ 5.04 eV (deep ultraviolet) when integrated with 2D β-In2Se3, Eg ~ 1.43eV (near infra-red) can reveal potential applications in the optoelectronic field.

Shear Bond Strength to Enamel, Mechanical Properties and Cellular Studies of Fiber-Reinforced Composites Modified by Depositing SiO2 Nanofilms on Quartz Fibers via Atomic Layer Deposition.

Poor interfacial bonding between the fibers and resin matrix in fiber-reinforced composites (FRCs) is a significant drawback of the composites. To enhance the mechanical properties of FRC, fibers were modified by depositing SiO2 nanofilms via the atomic layer deposition (ALD) technique. This study aims to evaluate the effect of ALD treatment of the fibers on the mechanical properties of the FRCs. The quartz fibers were modified by depositing different cycles (50, 100, 200, and 400) of SiO2 nanofilms via the ALD technique and FRCs were proposed from the modified fibers. The morphologies, surface characterizations of nanofilms, mechanical properties, and cytocompatibility of FRCs were systematically investigated. Moreover, the shear bond strength (SBS) of FRCs to human enamel was also evaluated. The SEM and SE results showed that the ALD-deposited SiO2 nanofilms have good conformality and homogeneity. According to the results of FTIR and TGA, SiO2 nanofilms and quartz fiber surfaces had good chemical combinations. Three-point bending tests with FRCs showed that the deposited SiO2 nanofilms effectively improved FRCs' strength and Group D underwent 100 deposition cycles and had the highest flexural strength before and after aging. Furthermore, the strength of the FRCs demonstrated a crescendo-decrescendo tendency with SiO2 nanofilm thickness increasing. The SBS results also showed that Group D had outstanding performance. Moreover, the results of cytotoxicity experiments such as cck8, LDH and Elisa, etc., showed that the FRCs have good cytocompatibility. Changing the number of ALD reaction cycles affects the mechanical properties of FRCs, which may be related to the stress relaxation and fracture between SiO2 nanofilm layers and the built-up internal stresses in the nanofilms. Eventually, the SiO2 nanofilms could enhance the FRCs' mechanical properties and performance to enamel by improving the interfacial bonding strength, and have good cytocompatibility.

Aggregation and adhesion ability of various probiotic strains and Candida species: An in vitro study

Background/purposeThe ability of probiotics to inhibit Candida adhesion is a crucial characteristic that prevents Candida colonization and infection progression. This study aimed to explore aggregation, adhesion, and cell surface characterization of probiotic and Candida strains and to evaluate the effect of probiotics and their cell-free supernatants (CFSs) as postbiotics on Candida adhesion to human oral keratinocytes. Materials and methodsEight probiotic strains and five reference Candida strains were tested for autoaggregation, coaggregation, adhesin on human oral keratinocytes (H357), and cell surface properties. The anti-Candida adhesion activities of probiotic strains and CFSs were investigated. ResultsThe results showed that most probiotics exhibited high adhesion to H357 cells, specifically oral probiotic Lacticaseibacillus rhamnosus SD4, Limosilactobacillus fermentum SD7, and L. rhamnosus SD11, and adhesion ability of probiotic strains was strongly related to their autoaggregation, cell surface charges, and hydrophobicity. Candida strains also revealed a high level of adhesion to H357 cells. Candida albicans and Candida glabrata showed significantly higher adhesion abilities than others. After a combination of Candida with probiotics or their CFSs, Candida adhesion was significantly reduced. The anti-Candida adhesion property of probiotics was strongly related to their autoaggregation, coaggregation, and adhesion abilities. ConclusionThis study demonstrated that oral probiotic strains may be useful probiotics for preventing and treating oral candidiasis due to their high ability of aggregation, adhesion, and anti-Candida adhesion to H357 cells.

Mechanical Flexibility and Electrical Reliability of ZnO-Al Thin Films on Polymer Substrates Under Different External Deformation

Abstract Aluminum-doped zinc oxide (AZO) films have emerged as promising transparent electrodes for various optoelectronic applications due to their superior transparency, electrical conductivity, and cost-effectiveness compared to indium tin oxide (ITO). Despite their widespread use, investigations into the electromechanical properties of AZO films, especially under various mechanical deformations, remain limited. This study employs RF magnetron sputtering to deposit AZO films on polyethylene naphthalate (PEN) substrates and explores their mechanical behavior through uniaxial tensile fragmentation and bending tests, coupled with in-situ optical microscopy. Changes in electrical resistance of AZO films were monitored in situ during deformation. Fatigue behavior was examined to further understand mechanical failure, and SEM was used for surface characterization. A critical strain of about 3.1 percent was detected during uniaxial tensile testing, marking the onset of cracks in AZO-coated PEN. In contrast to thicker films, thinner films demonstrated improved stretchability beyond the initiation of crack onset strain. Tension and compression bending tests revealed that the material has excellent bendability, as shown by its critical radii of 5.4 mm and 3.9 mm, respectively. The bending reliability of AZO films under compression was found to be superior than that under tension. Bending fatigue experiments demonstrated that AZO films could withstand cyclic stress without experiencing no ticeable cracks after 100 cycles and with very minor resistance change. This study contributes to the creation of more reliable and optimized flexible optoelectronic devices by giving substantial quantitative data on the performance of AZO films when exposed to mechanical stress.

Surface Modification of Zn-Cu Alloy with Heparin Nanoparticles for Urinary Implant Applications.

In this work, an investigation on the Zn-Cu alloy coated with heparin was conducted in order to explore the potentiality of its application as a feasible alternative for biodegradable implants, with the specific goal of addressing the issue of encrustation in the urinary system. The stability of the nanoparticles were characterized by dynamic light scattering. Typical surface characterization such as X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were used to demonstrate a successful immobilization of the NPs. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in artificial urine (AU) at 37 °C. The 8 weeks in vivo degradation, encrustation resistance, hemocompatibility, and histocompatibility were investigated by means of implantation into the bladders of rats. Both in vitro and in vivo degradation tests exhibited a higher degradation rate for Zn-Cu and NPs groups when compared to pure Zn. Histological evaluations and hemocompatibility revealed that there was no tissue damage or pathological alterations caused by the degradation process. Furthermore, antiencrustation performance and urinalysis results confirmed that the modified alloy demonstrated significant encrustation inhibitory properties and bactericidal activity compared to the pure Zn control. Our findings highlight the potential of this modified alloy as an antiencrustation biodegradable ureteral stent.

High temperature synthesis, surface characterization, and photoluminescence property of boron carbon nitride

The present study demonstrates the synthesis of boron carbon nitride (BCN) by molten salt method which utilizes melamine (source of carbon and nitrogen), boric acid (source of boron) and potassium chloride as the salt. The synthesis is performed at 915 °C for 4 h under N2-atmosphere. The synthesized material is further acid-treated. The physicochemical characterization data for as-synthesized and acid-treated materials confirm successful synthesis of BCN. SEM and AFM data display that synthesized BCN pre and post acid-treatment exhibit sheet-type morphology. Thermogravimetric analysis data confirm that the acid-treated material is thermally stable up to 800 °C, with only 2 % mass-loss is observed till 800 °C. Water contact angle measurement study demonstrates that acid-treatment significantly improves the surface hydrophilicity. Additionally, the low photoluminescence peak intensity of the acid-treated material indicates low electron-hole pair recombination rate. The synthesized material may be useful for the photocatalytic degradation of potentially toxic chemicals from water.

Tribological Behavior and Wear Mechanism of Cu-SiO2 Sintered Composite under Different Sliding Speeds

In this paper, the tribological behavior of Cu-SiO2 composite against 1045 steel was studied. Based on the characterization of worn surface, worn subsurface and wear debris in morphology and composition, the friction layer effects on the tribological behavior of coupled materials and the wear mechanism were discussed. Abrasive wear and adhesive wear are the dominant mechanisms at the 0.56 m/s–1.12 m/s condition. Delamination wear and oxidation wear are the dominant wear mechanisms at the 1.68 m/s–2.24 m/s condition. Plastic and thermal deformation cause the evolution in morphology and structure of the tribolayer of Cu-SiO2. There is a certain correlation between the friction coefficient and the variation in friction temperature during sliding wear of Cu-SiO2 and 1045 steels. The addition of SiO2 induces the accumulation of frictional heat at the friction interface, which leads to an increase in the average temperature of the contact surface and transfer.

Pre-hardening water quenching effect on the wear resistance of TiCN coated 4140 steels

In this comprehensive study, we investigated the mechanical and wear characteristics of AISI 4140 steel specimens subjected to quench hardening and coated with Titanium Carbo Nitride (TiCN) using the Physical Vapor Deposition (PVD) technique. Our analysis encompassed microstructure characterization, cross-sectional examination of the coating layer, phase analysis, microhardness evaluation, and wear behavior assessment, aiming to discern the combined impact of TiCN coating and pre-hardening treatment. The surface imaging and characterization of the coating layer were conducted employing Energy Dispersive Spectroscopy (EDS) assisted Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. Hardness measurements were performed utilizing a microhardness testing apparatus. Furthermore, wear assessments were executed employing a ball-on-disc tribometer, employing two distinct loads of 20 and 40 N. Results revealed that the pre-hardening process led to a remarkable coating surface hardness of 2473 HV, surpassing the 2230 HV recorded in AISI 4140 steel without pre-hardening. Pre-hardening notably improved coating thickness and hardness, and substantially reduced wear rates, especially when combined with TiCN coating. In conclusion, the combined approach of pre-hardening and TiCN coating emerges as a highly effective strategy for enhancing the mechanical and wear properties of this steel alloy.

Optical and Electromechanical Design and Implementation of an Advanced Multispectral Device to Capture Material Appearance.

The application of materials with changing visual properties with lighting and observation directions has found broad utility across diverse industries, from architecture and fashion to automotive and film production. The expanding array of applications and appearance reproduction requirements emphasizes the critical role of material appearance measurement and surface characterization. Such measurements offer twofold benefits in soft proofing and product quality control, reducing errors and material waste while providing objective quality assessment. Some image-based setups have been proposed to capture the appearance of material surfaces with spatial variations in visual properties in terms of Spatially Varying Bidirectional Reflectance Distribution Functions (SVBRDF) and Bidirectional Texture Functions (BTF). However, comprehensive exploration of optical design concerning spectral channels and per-pixel incident-reflection direction calculations, along with measurement validation, remains an unexplored domain within these systems. Therefore, we developed a novel advanced multispectral image-based device designed to measure SVBRDF and BTF, addressing these gaps in the existing literature. Central to this device is a novel rotation table as sample holder and passive multispectral imaging. In this paper, we present our compact multispectral image-based appearance measurement device, detailing its design, assembly, and optical considerations. Preliminary measurements showcase the device's potential in capturing angular and spectral data, promising valuable insights into material appearance properties.

An imprint-based approach to replicate nano- to microscale roughness on gelatin hydrogel scaffolds: surface characterization and effect on endothelialization

Biologization of biomaterials with endothelial cells (ECs) is an important step in vascular tissue engineering, aiming at improving hemocompatibility and diminishing the thrombo-inflammatory response of implants. Since subcellular topography in the scale of nano to micrometers can influence cellular adhesion, proliferation, and differentiation, we here investigate the effect of surface roughness on the endothelialization of gelatin hydrogel scaffolds. Considering the micron and sub-micron features of the different native tissues underlying the endothelium in the body, we carried out a biomimetic approach to replicate the surface roughness of tissues and analyzed how this impacted the adhesion and proliferation of human umbilical endothelial cells (HUVECs). Using an imprinting technique, nano and micro-roughness ranging from Sa= 402 nm to Sa= 8 μm were replicated on the surface of gelatin hydrogels. Fluorescent imaging of HUVECs on consecutive days after seeding revealed that microscale topographies negatively affect cell spreading and proliferation. By contrast, nanoscale roughnesses of Sa= 402 and Sa= 538 nm promoted endothelialization as evidenced by the formation of confluent cell monolayers with prominent VE-cadherin surface expression. Collectively, we present an affordable and flexible imprinting method to replicate surface characteristics of tissues on hydrogels and demonstrate how nanoscale roughness positively supports their endothelialization.

Surface characterization and Remazol Red adsorption by asymmetric polyethersulfone membranes modified by polyelectrolyte complexes

AbstractPolyethersulfone (PES) membranes containing 4‐fluorophenyl sulfone‐terminated poly(diallylpiperidinium hexafluorophosphate)‐sulfonated poly(ethylene terephthalate) polyelectrolyte complexes (PECs) were obtained via phase inversion using three different methods that enabled the complexation of polyelectrolytes (PELs) to occur before, after, and during membrane formation. Atomic force microscopy‐infrared spectroscopy analysis revealed varying concentrations of the polyanion depending on the preparation method and confirmed the presence of PECs in the membranes, highlighting an increase in surface roughness. Zeta potential measurements demonstrated positive surface charges for the membrane comprising PES and the polycation. The reduction in zeta potential in PEC membranes corresponded with the neutralization of positive groups by sulfonated poly(ethylene terephthalate. Scanning electron microscopy micrographs depicted surface imperfections in PEC membranes, emphasizing the influence of PECs on membrane surfaces. The water contact angle decreased, indicating increased hydrophilicity in PEC membranes. Additionally, dye adsorption results showcased significant adsorption, with the membranes absorbing at least 60% of Remazol Red from an aqueous solution. Notably, the Blend membrane outperformed others, exhibiting an exceptional adsorption rate exceeding 92%.