Material Surface Research Articles

Effect of micropatterning with nanowire-based microcavity array on bacterial enrichment and selective distribution

The micro-patterned topography can affect bacterial enrichment and selective distribution by modifying the characteristics of material surface. In this study, we fabricated microcavity patterned silicon surfaces, and quantitatively explored the amount and distribution of Escherichia coli (E. coli) cells attached on a series of defined topographies. The results showed that E. coli cells enrichment was significantly increased on silicon nanowires-based microcavity array when compared to nanowires patterned silicon wafer. Furthermore, the microcavity diameter can control bacterial distribution by changing hydrophilic performance of interface. With the microcavity diameter of 7 µm, the cells colonized into the microcavity almost in its entirety, whilst distributed around the microcavity completely with 10 µm diameter, regardless of centre distances. This phenomenon can be explained by the Cassie-Baxter model equation according to the wettability. The distribution of bacterial enrichment changed with the silicon surfaces turning from non-wetting status to wetting status when treated with oxygen plasma to modify the hydrophobicity. These results demonstrated that microcavity patterned surface could favor bacterial enrichment on silicon and strictly confined bacterial distribution inside/outside the microcavity. Moreover, the nanowires inside microcavity can also increase electron conductivity and reduce the internal resistance, thus providing scientific evidence for the design of wearable microbial fuel cell with rational optimization and integration of different components for electronic skin.

Potentiodynamic Polarization Study of PH3 Electrochemical Oxidation

ABSTRACTIn this study, the electrochemical behaviour of phosphine in sulphuric acid solutions on the surface of various electrode materials was conducted by voltammetric investigations. The effects of electrode materials such as lead, copper, and platinum electrodes on the PH3 anodic oxidation were investigated. Polarization curves were recorded by saturating the sulphuric acid solution with phosphine. The results received show that the electrochemical oxidation of phosphine on the lead electrode is accompanied by an oxygen evolution potential and, on the copper electrode, copper (II) ions show catalytic effects. The maximum anodic oxidation of phosphine on a platinum electrode was observed at the potential range of 0.8–1.0 V, and in the presence of copper (II) ions on the polarogram a maximum of phosphine oxidation is recorded at a potential of approximately 0.1–0.2 V.

Research Progress on Current-Carrying Friction with High Stability and Excellent Tribological Behavior

Current-carrying friction affects electrical contact systems like switches, motors, and slip rings, which determines their performance and lifespan. Researchers have found that current-carrying friction is influenced by various factors, including material type, contact form, and operating environment. This article first reviews commonly used materials, such as graphite, copper, silver, gold, and their composites. Then different contact forms like reciprocating, rotational, sliding, rolling, vibration, and their composite contact form are also summarized. Finally, their environmental conditions are also analyzed, such as air, vacuum, and humidity, on frictional force and contact resistance. Additionally, through experimental testing and theoretical analysis, it is found that factors such as arcing, thermal effects, material properties, contact pressure, and lubrication significantly influence current-carrying friction. The key mechanisms of current-carrying friction are revealed under different current conditions, including no current, low current, and high current, thereby highlighting the roles of frictional force, material migration, and electroerosion. The findings suggest that material selection, surface treatment, and lubrication techniques are effective in enhancing current-carrying friction performance. Future research should focus on developing new materials, intelligent lubrication systems, stronger adaptability in extreme environments, and low friction at the microscale. Moreover, exploring stability and durability in extreme environments and further refining theoretical models are essential to providing a scientific basis for designing efficient and long-lasting current-carrying friction systems.

Optimizing Cutting Parameters for Effective Turning of EN-31 Steel by Utilizing Vegetable-Based Cutting Fluids as a Coolant

<div>The primary objective of this article is to study the improvement of machining efficiency of EN-31 steel by optimizing turning parameters using newly developed cutting fluids with different proportions of aloe vera gel and coconut oil, utilizing the Taguchi technique. Furthermore, performance metrics including material removal rate (MRR), surface roughness, and tool wear rate (TWR) were assessed. Analysis of variance (ANOVA) suggested that as cutting speed and feed increase, the MRR is positively influenced, but likewise tool wear is intensified. The surface roughness exhibited a positive correlation with cutting speed, and a negative correlation with increasing both cutting speed and feed. It was found that the maximum MRR value was attained at a cutting speed of 275 m/min, a feed rate of 1.00 mm/rev, and a cutting fluid composition of 30% aloe vera and 70% coconut oil. For the best surface smoothness, it is advisable to adjust the cutting speed to 350 m/min and the feed rate to 0.075 mm/rev. A cutting speed of 275 m/min and a feed rate of 1.00 mm/rev led to a lower TWR. The results suggest that the combined use of coconut oil and aloe vera as cutting fluids improves the turning quality of EN-31 steel, particularly when employing a combination of 30% aloe vera and 70% coconut oil. As a possible solution for performance problems in achieving desired results during the turning of EN-31 steels, these recommendations may be used in industries to enhance turning performance.</div>

Hydrogen diffusion and trapping in a cryogenic processed high-Cr ferrous alloy

The effect of hydrogen diffusion and trapping was studied in a high-Cr ferrous alloy using an inverted scanning Kelvin probe and thermal desorption spectroscopy in correlation with microstructure and residual stress study. In addition, different processing of ferritic/martensitic 9Cr1WTaV alloy (EUROFER97) was tested in correlation with observed selected properties to observe induced changes in material degradation and surface. The activation energies for hydrogen traps were shown to have distinct peaks corresponding to different trapping mechanisms, including matrix dislocations and grain boundaries. For the cryogenically treated sample, an additional peak was also identified and correlated with increased carbide precipitation.

Unveiling the mechanism secret of abrasion emissions of particulate matter and microplastics

Recent research highlights that non-exhaust emissions from the abrasion of tires and other organic materials have emerged as a substantial source of airborne particulate matter and marine microplastics. Despite their growing impact, the underlying mechanisms driving these abrasion emissions have remained largely unexplored. In this study, we uncover that abrasion emissions from organic materials are fundamentally governed by a fatigue fracture process, wherein particles are progressively detached from the material surface under cyclic abrasion loads. Our findings demonstrate that these emissions increase significantly only when the applied abrasion loads surpass the material’s toughness threshold. We establish a scaling relationship between the concentration of emitted particulate matter and the measurable crack propagation rate of the organic material, offering a robust quantitative method to estimate abrasion emissions. This work not only introduces a novel mechanistic framework for understanding particulate matter pollution from organic material abrasion but also provides a scientific basis for developing strategies to mitigate emissions of airborne particulates and marine microplastics.

A HOF-101@AgNPs-based dual-signal mode aptasensor for electrochemiluminescence and fluorescence detection of E. coli O157:H7

Escherichia coli O157:H7 (E. coli O157:H7) emerges as a foodborne pathogen, emphasizing the imperative for creating precise detection tools. An ultrasensitive electrochemiluminescence/fluorescence (ECL/FL) dual-signal mode aptasensor was constructed for the detection of E. coli O157:H7. Ultrafine silver nanoparticles were loaded on the surface of hydrogen-bonded organic skeleton materials by in-situ photoreduction method, and then combined with aptamers that can identify specific targets to prepare HOF-101@AgNPs@Apt, greatly simplifying the ECL/FL dual-signal mode probe fabrication process and improving sensing reliability. HOF-101@AgNPs@Apt had both strong ECL luminescence and fluorescence, resulting in a high detection sensitivity. The low limit of detection (LOD) for ECL and FL were 0.48 CFU mL−1 and 2.39 CFU mL−1, respectively. Moreover, the proposed dual-signal mode aptasensor has been successfully applied to determine E. coli O157:H7 levels in tap water and milk with superior accuracy and high antiinterference capability, providing a promising method for food safety monitoring.

Дослідження впливу різних наповнювачів на атмосферостійкість асфальтобетонів

Introduction. The properties of bituminous-mineral materials are determined by the bonds formed between individual mineral grains and depend on the characteristics of the bitumen, the thickness of the bitumen layer covering the mineral grains, as well as the interaction processes between the mineral materials and bitumen at their joint interface. To ensure a strong and stable bond between the grains, the bitumen must evenly cover the surface of the mineral materials with a thin layer. To improve the strength of road pavement made from bituminous-mineral material, it is necessary for the maximum amount of bitumen to be adsorbed by the mineral material, minimizing the content of free bitumen. Problem Statement. Depending on the nature of the mineral material and the chemical composition of the bitumen, the properties of its thin layers change in various ways. On an active mineral surface, the strength of the bitumen in a thin layer increases as the thickness decreases, while on an inactive surface, the strength of the bitumen remains largely unchanged with a decrease in layer thickness.

Enhancing of Material Removal Rate and Surface Roughness in Wire EDM Process using Grey Relational Analysis

Enhancing of Material Removal Rate and Surface Roughness in Wire EDM Process using Grey Relational Analysis

Mechanical Performance of Cellulose Nanocrystal and Bioceramic-Based Composites for Surgical Training.

This study evaluated the mechanical performance of a cellulose nanocrystal (CNC)-based composite, consisting of hydroxyapatite and natural fibers, mimicking the mechanical properties of real bone. The effect of natural nanofibers on the cutting force of the composite was evaluated for suitability in surgical training. Although hydroxyapatite has been extensively studied in bone-related applications, the exploration of epoxy-based composites incorporating both hydroxyapatite and CNC represents a novel approach. The evaluation involved a load cell with an oscillating saw. The uniform distribution of CNCs within the composite was assessed using 3D X-ray imaging. The cutting force was found to be 4.005 ± 0.5469 N at a feed rate of 0.5 mm/s, comparable to that required when cutting real bone with the osteon at 90°. The 90-degree orientation of the osteon aligns with the cutting direction of the oscillating saw when performing knee replacements on the tibia and femur bones. The addition of CNCs resulted in changes in fracture toughness, leading to increased material fragmentation and surface irregularities. Furthermore, the change in the cutting force with depth was similar to that of real bone. The developed composite material enables bone-cutting surgeries using bioceramics and natural fibers without the risks associated with cadavers or synthetic fibers. Mold-based computed tomography data allows for the creation of various bone forms, enhancing skill development for surgeons.

Design, Testing, and Experimental Validation of a Rotary Vibration-Assisted Polishing Device (RVAPD) for Enhanced Machining and Surface Quality.

A rotary vibration-assisted polishing device (RVAPD) is designed to enhance polishing force by converting PZT's linear motion into the rotary motion of a central platform via a flexible mechanism, improving material surface quality. The RVAPD is optimized, simulated, and tested to meet high-frequency and large-amplitude non-resonant vibration polishing requirements. Its structure, designed using theoretical models and finite element software, offers a wide range of polishing parameters. Performance parameters are validated through open-loop tests, confirming effectiveness in polishing experiments. The lever mechanism and Hoeckens connection enhance vibration parameters and motion efficiency, reducing surface flaws in SiC and improving uniformity. Adjusting the RVAPD structure and using the proposed method significantly improve SiC surface quality.

Tuneable mesoporous silica material for hydrogen storage application via nano-confined clathrate hydrate construction

Safe storage and utilisation of hydrogen is an ongoing area of research, showing potential to enable hydrogen becoming an effective fuel, substituting current carbon-based sources. Hydrogen storage is associated with a high energy cost due to its low density and boiling point, which drives a high price. Clathrates (gas hydrates) are water-based (ice-like) structures incorporating small non-polar compounds such as H2 in cages formed by hydrogen bonded water molecules. Since only water is required to construct the cages, clathrates have been identified as a potential solution for safe storage of hydrogen. In bulk, pure hydrogen clathrate (H2O-H2) only forms in harsh conditions, but confined in nanospaces the properties of water are altered and hydrogen storage at mild pressure and temperature could become possible. Here, specifically a hydrophobic mesoporous silica is proposed as a host material, providing a suitable nano-confinement for ice-like clathrate hydrate. The hybrid silica material shows an important decrease of the pressure required for clathrate formation (approx. 20%) compared to the pure H2O-H2 system. In-situ inelastic neutron scattering (INS) and neutron diffraction (ND) provided unique insights into the interaction of hydrogen with the complex surface of the hybrid material and demonstrated the stability of nano-confined hydrogen clathrate hydrate.

Surface Science and Engineering for Electrochemical Materials.

ConspectusIn electrochemical energy storage systems, the reversible storage capacity of battery materials often degrades due to parasitic reactions at the electrode-electrolyte interface, transitional metal dissolution, and metallic dendrite growth at the surface. Surface engineering techniques offer the opportunity to modify the composition and structure of a surface, thereby enabling control over chemical reactions occurring at the surface and manipulating chemical interactions at the solid-solid or solid-liquid interface. These modifications can help stabilize the surface of electrode materials and prevent unwanted reactions with electrolytes without changing the original properties of the bulk structure. This allows for achieving full theoretical capacity and maximizing battery material capacity retention with minimal overpotentials. In the past decade, our teams have been working on developing a variety of surface engineering techniques. These include applying atomic and molecular layer deposition (ALD and MLD), templating, doping, and coating via wet-chemical processes to stabilize the surfaces of electrode materials. The aim is to mitigate parasitic side-reactions without impeding charge transfer kinetics, suppress dendrite growth, and ultimately improve the electrode performance.This Account summarizes the research conducted in our research laboratory with an aim to improve battery cycling durability and efficiency by modifying electrode surfaces. We have employed techniques such as ALD, MLD, templating, and wet-chemical processes to illustrate how the stabilized surface improves the performance of lithium-ion (Li-ion), solid-state electrolytes and magnesium-metal (Mg-metal) batteries. For instance, by applying ultrathin layers of inorganic (e.g., Al2O3) or organic-inorganic coatings (e.g., alucone, lithicone, and polyamides) to the surface of LiNixMnyCozO2 (x + y + z = 1, NMC) and silicon (Si) electrodes─usually just a few angstroms or nanometers thick─we have observed notable improvements in cycling efficiency and durability. When using ultrathick electrodes, the traditional electrode fabrication has a problem with high tortuosity, which hinders both rate capability and long-term cycling. To solve this issue, three-dimensional templates have been employed to reduce electrode tortuosity, enabling high-rate performance and long-term cycling. In the case of Mg-metal batteries, the buildup of an insulating MgO layer due to side reactions with electrolytes blocks Mg2+ ion transport, which can ultimately cause the battery to fail. To address this issue, we have developed an artificial solid-electrolyte interface using cyclized polyacrylonitrile and magnesium trifluoromethanesulfonate. This interface prevents the reduction of the carbonate electrolyte while allowing Mg2+ diffusion, ultimately boosting overall cell performance.This Account also discusses the significance of choosing suitable materials and effective surface engineering methods with the objective of enhancing surface properties while preserving the bulk properties of the electrodes. It is believed that surface modification and engineering can not only significantly improve the electrochemical performance of existing battery materials but also facilitate the development of new battery materials that were previously incompatible with current electrolytes. By highlighting these aspects, this Account underscores the transformative potential of surface modification and engineering in battery technology, paving the way for future innovations in energy storage solutions.

Study on plastic yield surfaces of pyramidal lattice materials with circular and rectangular cross-sections

The yield surfaces and the evolution of yield surfaces of a bending-dominated pyramidal lattice material under complex stress states considering the coupling effect of axial force and bending moment of a strut are studied theoretically. The two-dimensional primary yield surfaces, secondary yield surfaces, and complete yield surfaces of pyramidal lattice materials of two kinds of cross-section struts are obtained, and the analytical expressions of yield surfaces are established. The effects of the inclination angle and diameter-to-length ratio of the struts on the yield surfaces of pyramidal lattice materials with circular cross-sections are discussed. The results provide a basis for analyzing homogenized plastic properties of complex lattice material structures.

Study on the effects of ultrasonic vibration-assisted wire-EDM machining parameters on material removal rate and surface roughness of NiTiV shape memory alloy

Nickel-titanium (NiTi)-based shape memory alloys (SMAs) exhibit remarkable properties, making them increasingly demanding in various engineering and medical applications especially when these SMAs are manufactured with intricate shapes and sizes. This present study examines the machining of Ni50Ti48V2 SMA using ultrasonic-assisted WEDM with input parameters of pulse ON time (TON), pulse OFF time (TOFF), peek current (I), and servo voltage (SV) along with 20 kHz constant ultrasonic vibration on the responses of material removal rate (MRR) and surface roughness (Ra). RSM-BBD response surface methodology was used to conduct the experiments. It was inferred from analysis of variance (ANOVA) analysis, that as the peak current (I) and pulse ON time (TON) increased, the MRR increased by 65.76% and Ra decreased by 54.44%. The confirmation was carried out in USV-WEDM under optimal conditions, which shows that both the predicted and actual MRR and Ra are close to each other. When compared with conventional WEDM, the USV-WEDM shows significant improvement in MRR by 8.6% and also improved surface quality by 6.3%. The surface characteristics of Ni50Ti48V2 after machining were examined using field-emitted scanning electron microscopy, showing small irreularisation peaks and wavy surface topography at optimised parameter conditions. USV-WEDM showed a lower-order micro-hardness variation due to effective flushing of molten layer re-accumulation as compared to WEDM. When comparing the base and machined samples, the temperatures of austenite and martensite are nearly the same, indicating that shape memory effects are unaffected by the USV-WEDM process.

Human gingival fibroblast response on zirconia and titanium implant abutment: A systematic review.

The peri-implant region, where restoration interfaces with mucosal tissue, plays an essential role in overall implant success and is just as important as osseointegration. The implant abutment materials are in intimate contact with human gingival fibroblasts (HGFs). This study compares the proliferation of HGFs between zirconia and titanium abutments used in dental implants. An electronic search was performed using PubMed, EMBASE, and Web of Science databases. English articles based on in vitro studies testing HGFs proliferation on zirconia and titanium implant abutment materials were included. A quality assessment of the selected study was performed using the web-based Science in Risk Assessment and Policy (SciRAP) tool. The HGFs proliferation and cellular morphology tests on zirconia and titanium materials from the included studies were summarized, exploring the role of material surface characteristics. The electronic search yielded 401 studies, of which 17 were selected for inclusion. Zirconia exhibited comparable or superior efficacy in promoting the proliferation of HGFs compared to titanium. Observations on cellular morphology showed similar outcomes for both materials. Establishing a definitive relationship between contact angle, surface roughness, and their influence on cellular response remains challenging due to the varied methodological approaches in the reviewed studies. Based on the findings of this systematic review, zirconia shows comparable reliability to titanium as an abutment material for HGFs proliferation, with comparable or superior HGFs proliferative outcomes.

Effect of Laser Surface Texturing Process on Dry Sliding Wear Behavior of NiTi Shape Memory Alloy Used in Airplane

In this study, the effect of laser surface texturing (LST) applied to NiTi Shape Memory Alloy (SMA) on the dry sliding wear behavior of the material was investigated. After polishing and cleaning the material surface, a pitted surface texturing process was performed using a femtosecond laser under atmospheric conditions. After the surface texturing process, dry sliding wear tests were performed at room temperature. When the wear behavior of the laser-applied and non-laser-applied test samples was evaluated comparatively, it was determined that the coefficient of friction (COF) of the laser-applied samples under 1N load was approximately 17% lower. It was determined that the decrease in the COF value decreased with increasing load. However, the wear amount of the LSD-applied NiTi SMA was higher than the untreated sample. It was evaluated that this situation was due to thermal softening that occurred depending on the ablation geometry and dimensions.

Blocking of Gas–Liquid Coalescing Filters with Accumulated Oil during the On–Off Operation of a Filtration System

The study aims to eliminate the effect of coalescing filter blocking due to on–off operation by changing the wetting properties of the non-woven fiberglass filter media through their chemical modification with the use of a polydimethylsiloxane (PDMS) solution in hexane and a few commercial products that give the surface oleophobic properties. The best results—high separation efficiency, no redispersion of droplets at the outlet, and low flow resistance—were obtained for materials coated by immersion in a 0.2% PDMS solution, for which a reduction in oleophilicity was found, but the material was not oleophobic and still moderately wetted with the test liquid. The corresponding static contact angle with the VG-46 rotary compressor oil measured on the flat borosilicate glass wafer made of the same material as the fiberglass media was equal to 54° for the PDMS dip-coated surface. Moreover, the good stability of the applied polymer on the material surface was confirmed by the SEM imaging, the FTIR analysis, and maintaining a high performance in multiple tests run for a single coalescing element.

Study of argon plasma modified Pd/AlGaN/GaN high electron mobility transistor for superior hydrogen gas detection

The surface and microstructure of the sensitive material play an important role in the gas adsorption and detection. However, few report of the surface modification affection on the work function-based gas sensor is carried out. Herein, facile Ar+ modification is proposed and utilized to modify the surface of the Pd sensitive layer, which acts as the gate of a AlGaN/GaN high electron mobility transistor (HEMT) based hydrogen (H2) gas sensor. Results show that the Pd surface is significantly changed to smoother microstructure by 5 s Ar+ modification. Compared with the device without Ar+ modification, the response values increase by ∼ twice at all operating temperatures. Interestingly, the response time is pronouncedly shortened from 10 to 2.3 s at 500 ppm, suggesting the significant effect of Ar+ modification in the enhancement of gas detection. At the optimized operating temperature of 120 °C, a high response of 739% and an ultrafast response time of 1.4 s are observed for the 500 ppm H2 gas. In addition, this sensor exhibits a low limit of detection ∼200 ppb, along with excellent repeatability, consistency, and selectivity. Our study indicates that the facile Ar+ modification of the gate surface is a highly effective technology in the enhancement of gas detection and may provide a novel approach for the design and development of all the work function type gas sensors.

Covalently Linked 2D-Co3O4/GO Heterostructures: Catalytic and Electrochemical Properties.

Covalently cross-linked 2D heterostructures may represent a ground-breaking approach to creating materials with multifunctionalities. To date, however, this field still remains relatively unexplored. In the present work, Co3O4/GO covalently linked heterostructures (Co3O4/GO-CL) were produced using 2D-Co3O4 functionalized with (3-aminopropyl)triethoxysilane (APTES) to react with the carboxyl groups of graphene oxide (GO). The surface and interface properties of the final material were assessed through electrochemical and catalytic studies. We found that the covalent bonds lead to a self-standing and ordered final structure, not observed for the noncovalent material (Co3O4/GO-nCL), also produced for comparison. The catalytic activity of Co3O4/GO-CL over the degradation of Rhodamine 6G showed great performance and the possibility of recycling the catalyst. Electrochemical evaluation stated higher specific capacitance for the covalently bonded material (468 F g-1 against 110 F g-1). Overall, results showed that the covalent bonds may be improving charge-transfer and interfacial area features, thus leading to enhanced catalytic and electrochemical performances.