Short Service Life Research Articles

Fabrication of microplastic-free biomass-based Masks: Enhanced Multi-functionality with All-natural fibers

With the coronavirus-2019 epidemic, disposable surgical masks have become a common personal protective necessity. However, off-the-shelf masks have low filtration efficiency and short service life and can only physically isolate pathogens, easily leading to secondary infection and cross-infection between users. Additionally, they produce debris and microplastics, which can be inhaled by the human body and cause serious diseases. To address this, this study introduced a brand-new, microplastic-free, long-life, biodegradable, self-disinfecting, and gas-sensitive mask made of basal dialdehyde-chitosan crosslinked animal-collagen/plant composite fibers (CP-Mask) with an asymmetric bilayer structure using scalable paper-processing technology. The CP-Mask demonstrated outstanding filtration performance (95.9%) for particulate matter with various sizes and constantly maintained filtration efficiency even after 20 friction cycles. The CP-Mask also exhibited stable and lasting antibacterial properties, with significant inhibition rates of 99.21% for Staphylococcus aureus and 98.86% for Escherichia coli and could effectively filter bacterial aerosols. In addition, CP-Mask realized the real-time detection of respiratory ammonia concentration and timely identified the ammonia level. The average response value was 68.26%, and the average response time was 159.3 s, presenting good circulatory stability and is suitable for early diagnosis of ammonia-related diseases. Breakthrough, the origin of natural ingredients, fundamentally makes CP-Mask less likely to emit microplastics than commercially available masks and endows it with complete biodegradability in soil within three months, eliminating the risk of microplastic inhalation from the source. The proposed CP-Mask provides a new idea to facilitate personal health monitoring and portability of medical protection equipment regarding biocompatibility, biodegradability, self-disinfection, and ammonia sensing ability.

Finite element analysis and experimental study on the sealing performance of low-phenyl silicone rubber sealing rings

PurposeThe brake pipe system was an essential braking component of the railway freight trains, but the existing E-type sealing rings had problems such as insufficient low-temperature resistance, poor heat stability and short service life. To address these issues, low-phenyl silicone rubber was prepared and tested, and the finite element analysis and experimental studies on the sealing performance of its sealing rings were carried out.Design/methodology/approachThe low-temperature resistance and thermal stability of the prepared low-phenyl silicone rubber were studied using low-temperature tensile testing, differential scanning calorimetry, dynamic thermomechanical analysis and thermogravimetric analysis. The sealing performance of the low-phenyl silicone rubber sealing ring was studied by using finite element analysis software abaqus and experiments.FindingsThe prepared low-phenyl silicone rubber sealing ring possessed excellent low-temperature resistance and thermal stability. According to the finite element analysis results, the finish of the flange sealing surface and groove outer edge should be ensured, and extrusion damage should be avoided. The sealing rings were more susceptible to damage in high compression ratio and/or low-temperature environments. When the sealing effect was ensured, a small compression ratio should be selected, and rubbers with hardness and elasticity less affected by temperature should be selected. The prepared low-phenyl silicone rubber sealing ring had zero leakage at both room temperature (RT) and −50 °C.Originality/valueThe innovation of this study is that it provides valuable data and experience for the future development of the sealing rings used in the brake pipe flange joints of the railway freight cars in China.

Improving micro-cathode arc thruster durability through semiconductor surface flashover (SSF) ignition technique

Abstract The micro-cathode arc thruster (μCAT) is a promising micro-propulsion technology. However, the short service life of the conductive film-triggering units is one of the important factors limited its application. In this study, a novel semiconductor surface flashover (SSF) ignition method is proposed aiming at extending the ignition lifespan. Owing to the inherently different triggering mechanisms and physical processes, the SSF ignition system does not require a balance between ablation and re-deposition processes, which could potentially improve the reliability of the triggering process. It was found that the ignition voltage of the SSF unit increased with the gap distance, whereas that of the conductive carbon film triggering unit remained relatively constant. Furthermore, high-speed photography revealed that the discharge channel continuously ablated the conductive film system throughout the discharge cycle, whereas it had less contact with the semi-conductive ceramic surface, resulting in reduced erosion in the SSF system. Using the SSF unit, 500,000 consecutive ignition tests were conducted, and demonstrating its good reliability.

Cyanogroup-Modified PEO-Based Electrolytes Achieve High Free Al3+ Concentration and Improve the Transport Dynamics in Solid-State Aluminum-Ion Batteries.

Polymer-based solid electrolyte boasting ultra-high safety, energy density, mechanical strength and flexibility, attracting much attention in the field of battery applications. However, its widespread application is hindered by the low conductivity, insufficient aluminium salt dissociation, high crystallization degree, short service life, etc. To solve the above problems, a composite solid polymer electrolyte (SPE) design based on polyethylene oxide (PEO, Mw = 6 000 000) with AlCl3·6H2O as aluminum salt and butanedinitrile (SN) as plasticizer is proposed in this paper. The disorder and mobility of the PEO chains, conductivity, degree of aluminum salt dissociation, and service life are enhanced by the addition of plasticizer SN. Theoretical calculation demonstrates the formation of solvated sheath-like structure [SN…Al3+] has strong interactions with the polymer PEO, allowing rapid transport of Al3+ through the polymer segments. These results are also further verified by subsequent tests, which can reveal the Al3+ transport mechanism of room-temperature SPEs in a more reasonable way. Meanwhile, the relatively strong binding energy between PEO and SN can help to avoid the parasitic reaction between SN and Al, increase the service life of solid-state aluminium-ion batteries. Providing a promising solution for the design of solid-state battery electrolytes that can be applied at room temperature.

Recent Advances on upper limb Rehabilitation Robot

Background: With advances in medical technology and an aging population, the number of patients with upper limb movement disorders has increased, who are facing difficulties in selfcare and occupational integration. Traditional rehabilitation methods have limitations, such as unstable results, long cycle times, and insufficient resources. Therefore, upper limb rehabilitation robotics has emerged, combining robotics, medicine, and other fields to simulate upper limb movement for targeted rehabilitation training in order to improve effectiveness, shorten the cycle, and reduce the burden on therapists. Objective: This study aimed to introduce the classification, advantages and disadvantages, and development trend in existing upper limb rehabilitation robots and provide a basis for other researchers to understand the current status of their development and future trends. Methods: Various studies and patents on upper limb rehabilitation robots were reviewed, revealing the structural characteristics, along with the advantages and disadvantages, of typical robotic arms used for upper limb rehabilitation. Results: Through the analysis of various upper limb rehabilitation robots, the characteristics and problems of upper limb rehabilitation robots were identified, and the development trend of upper limb rehabilitation robots was prospected. Conclusion: Upper limb rehabilitation robots have many advantages, such as good adaptability, personalized customization, safety and reliability, etc., but they also have some disadvantages, such as difficult control, high manufacturing cost, and short service life. In the future, upper limb rehabilitation robots will develop towards simpler structures, greater comfort, affordability, diverse functions, better efficacy, and increased safety.

`Evaluation of the antimicrobial corrosion properties of electropolymerized poly(aniline-co-o-toluidine) films on carbon steel surfaces

Microbiologically influenced corrosion (MIC) can lead to structural weakening and shortened service life of carbon steel, resulting in serious economic losses and safety hazards. In particular, sulfate-reducing bacteria (SRB) produce hydrogen sulfide and sulfide during their growth and metabolism, which accelerates the corrosion of carbon steel. Thin films of poly(aniline-co-o-toluidine) (PA-co-POT) were electrodeposited on the surface of carbon steel using cyclic voltammetry in an electrolyte consisting of oxalic acid, aniline and o-toluidine monomers. The mechanical properties of the polymer films were analyzed by a micro-Vickers hardness tester. The corrosion resistance of the polymer films was evaluated by an electrochemical corrosion test and immersion test of the polymer films in a solution containing SRB and 3.5% NaCl. The results showed that PA-co-POT films have superior SRB corrosion resistance than single polymer films. The corrosion rate of PA-co-POT film was 0.0171mm/year, and the protection efficiency was 83% after 14 days of immersion in solution. In addition, due to the antibacterial properties of the PA-co-POT film, the adhesion of bacteria on its surface is significantly reduced, and local corrosion is also effectively inhibited. This study demonstrates the potential of electropolymerized aniline derivative copolymer films in preventing MIC of carbon steel and provides valuable insights for the development of new corrosion protection materials.

In-Situ Neutron Depth Profiling Studies (Measurements and Simulations) to Characterize the Surface of Silicon Anodes and Complementary Neutron Techniques for in-Situ and Operando Characterization

In-situ methods for characterizing electrochemical systems are becoming increasingly important to understand the mechanism of lithiation and delithiation processes. The characterization of surfaces that have been under electrochemical influence is of great interest because many electrochemical processes originate here and are therefore crucial for cell performance. Pure silicon anodes with their large volume expansion, which leads to a short service life, can be modified at WACKER company by partial lithiation of microscale silicon particles [1]. Such anode types promise higher specific capacity. Neutron depth profiling (NDP) is a very well suitable technique to study the Li quantity with depth dependence on the first micrometers. The NDP method uses the capture reaction of Li atoms and neutrons with subsequent decay into ions of well-defined energies. The depth at which ions are created in the material is defined from their energy loss through the material to the detector with an accuracy of tens of nanometers [2, 3]. After formation different lithiation stages of SiG anodes are presented and compared with simulations. The lithiation process involving SEI formation, electrode swelling and phase transformation from crystalline to amorphous is presented. In the second part, a brief overview of other neutron techniques for in-situ and operando characterization of individual battery components or entire cells is given [4].

Piano keys based on high-strength and high-toughness PMMA superhydrophobic composites for piano training applications

Traditional piano keys are usually made of wood and plastic, which have problems such as poor wear resistance, easy deformation, and short service life. This article aimed to explore the application effect of piano keys made of high-strength and high-toughness PMMA (polymethyl metacrylate) superhydrophobic composite materials in piano training. The performance and effectiveness of the new material piano keys were evaluated through a series of experiments and tests, and compared with traditional materials. This article selected high-strength and high-toughness PMMA superhydrophobic composite materials suitable for piano keys, and designed corresponding formulas. The performance testing of piano keys mainly evaluated the mechanical properties, wear resistance, and stability of high-strength and high-toughness PMMA superhydrophobic composite materials for piano keys. This indicated that this new material has excellent mechanical properties and can withstand long-term and high-strength use. In the design and implementation of piano training experiments, participants used piano keys made of high-strength and high-toughness PMMA superhydrophobic composite materials for training. They expressed satisfaction with the tactile feel of the new material’s buttons, believing that the touch is more accurate and comfortable, and can better control the strength and color of the notes. This study provided new ideas and solutions for improving the quality and effectiveness of piano training, and brought new opportunities for the development of piano manufacturing and music education.

Durability of non-woven geotextiles produced from recycled polyethylene terephthalate (PET)

Achieving the goals of sustainable development and circular economy requires recycling and reusing plastic materials. In this research, the durability of five needle-punched non-woven geotextiles were experimentally studied. The geotextiles were made of recycled PET (rPET), virgin PET (vPET), and combinations of rPET and vPET fibers. The samples were hydrolyzed for a period of 14, 28, and 56 days and the retained tensile strength and puncture resistance of the samples were determined at the end of each interval. Moreover, this study took the benefits from the capability of differential scanning calorimetry (DSC), Fourier transforms in infrared spectroscopy (FTIR) analysis, and scanning electron microscopy (SEM) images to interpret the results acquired. Testing on as-received products, it was understood that recycling process could increase crystallinity of the fibers, increasing the fibers fragility, reducing the tensile strength and elongation capacity of rPET fibers. Moreover, considering the borderline value of 50% retained strength, a shorter service life (up to 30%) of rPET products in comparison with vPET products, due to higher degradation rates, was observed.

The effect of surface roughness and microstructure on fretting fatigue properties of TC21 based on hierarchical multiscale modeling

In the aviation industry, structures made from high-strength titanium alloy TC21 frequently suffer from fretting fatigue (FF), resulting in shortened service life. FF is significantly influenced by the surface integrity (SI) parameters. This study aims to investigate the effect of SI parameters, including microstructure and surface roughness, on the FF properties of TC21. It is implemented by introducing the crystal plasticity finite element method (CPFEM). The CPFEM parameters of single grain of α-Ti in TC21 were obtained by fitting the experimental and simulation data of nanoindentation test. On this basis, the FF of TC21 is studied by means of a hierarchical multiscale modeling method, which couples a global model with a CPFEM sub-model. In the global model, surface roughness was considered. While in the CPFEM sub-model, microstructure was incorporated as well. The FF sub-model shows that the stress was unevenly distributed due to the inconsistency in mechanical behavior of TC21. both the maximum von Mises stress and the maximum Fatemi-Socie (FS) parameter occurred at the grain boundaries in the subsurface layer. The prismatic slip system is highly sensitive to FF. For the orientation of <100>∥X-axis, the lowest FS value of 1.137×e-2 was obtained at the surface roughness of 0.8μm, meaning the smallest damage. While the orientation of <110>∥X-axis and random orientation are most sensitive to FF, their FS values reaching 2.019×e-2 and 2.090×e-2, respectively.

Robust, intelligent photochromic cotton fabrics with superamphiphobicity and expedient UV detection ability

Multifunctional photochromic cotton fabrics have enormous application potential in our daily lives, but still suffer from poor durability, slow coloration, tedious fabrication process, and short service life. The hydrophilic and polysaccharide characteristics of cotton fabrics make them vulnerable to bacteria adhesion and proliferation. Herein, intelligent photochromic cotton fabrics featured with durable superamphiphobicity are fabricated by in situ growth of ZIF-8 nanoparticles encapsulating spirooxazine (SP) photochromic dyes on the fabric surface, followed by low surface energy treatment using a fluorocarbon resin (FR) via a dip-coating method. The resultant SP@ZIF-8/FR cotton fabrics exhibit superamphiphobicity with contact angles of over 150° to both water and oils (surface tension ≥30 mN/m). When exposed to UV light, the fabric rapidly changes its color from white to blue within 10 s and fades in 2 min under visible room light. The developed SP@ZIF-8/FR coating is durable against numerous damages in daily usage, such as machine laundry, abrasion and UV irradiation, without losing photochromic and superamphiphobic properties. The high durability and excellent reversible color response allow the coated fabric to intuitively and quantitatively monitor outdoor UV intensity. Owing to the presence of ZIF-8, the treated fabrics also show excellent antibacterial property with antibacterial rates of over 99 % against both E. coli and S. aureus. The developed fabric coating can be engineered to visually assess the UV intensity in the outdoor environment.

Лиофилизированные микроорганизмы как основа биочувствительного элемента БПК-биосенсора

Previously created laboratory models and commercially available BOD biosensors are usually formed using the biomass of microorganisms obtained by centrifugation of the culture fluid. In this work we developed and tested BOD biosensors based on lyophilized bacteria Paracoccus yeei VKM V-3302 and yeast Debaryomyces hansenii VKM Y-2482. The use of a lyophilized form of microorganisms makes it possible to switch to a new analysis format – the use of easily replaceable biosensitive elements with a short service life. It will simplify the introduction of BOD biosensors in environmental laboratories, enterprises and organizations involved in the routine determination of BOD using a methodology based on a 5-day sample incubation. The long shelf life (up to 2 years), low cost and easy applying of a dry preparation to the electrode will greatly facilitate the transportation of biosensitive elements to the end user, allow analysis in the field and at any time and will not require constant calibration of a sensor. It has been shown that the lyophilization process does not lead to significant changes in the metabolic activity of microorganisms. The biosensors are characterized by high sensitivity (the lower limit of BOD5 determination is 0.5 mgO2/dm3), convergence of results (4.5%) and are not inferior to existing analogs in terms of basic characteristics. They make it possible to analyze water samples classified as “pure” (BOD5 range 0.05–0.5 mg/dm3) and obtain results with a high correlation (R=0.9951) to the standard method. Thus, the use of bacteria P. yeei and yeast D. hansenii in a lyophilized form as part of the sensitive elements of BOD biosensors makes it possible to use them in prototypes of biosensors for mass production.

Application of Response Surface Methodology Experimental Design to Optimize Tribological Lubrication Characteristics

Total Knee Replacement (TKR) has become a standard operation for patients with joint disorders. Despite the fact that the number of procedures is increasing all the time, the short service life of implants remains a persistent concern for researchers. Understanding lubrication may aid in explaining tribological processes that lead to replacements that last well into the third decade of service. Likewise, wear and friction in total knee replacement (TKR) components are among the most common causes of implant failure. As a result, this study will evaluate the feasibility of using the polymer Poly Lactic Acid (PLA) for cartilage replacement in Total Knee Replacement (TKR) using plant-based oils as lubricants. Furthermore, the modifier will be added to plant-based oils as an additive to make them analogous to human bodily fluids. The present paper is applying the Box-Behnken design to optimize the performance and mechanical responses of bio-lubricants toward Poly Lactic Acid (PLA) as a tibial insert for cartilage replacement in Total Knee Replacement (TKR). The main objective of this paper is to develop an optimized method for the selection of plant-based oil parameters using Response Surface Methodology (RSM). A three-level three-factor Box-Behnken design (BBD) was used to investigate the interactions between the essential factors comprising load (45 kg to 90 kg), speed (60 rpm, 90 rpm and 360 rpm), and concentration (0ml, 5ml and 10ml) of bio-lubricants to accomplish the indicated prospect of using polymer for cartilage replacement. Canola oil, castor oil, and sunflower seed oil are considered vegetable oils, whereas Hyaluronic Acid (HA) is the friction modifier. The parameters are used to create a Box-Behnken design for predicting lubricant anti-wear qualities stated in terms of coefficient of friction, wear rate and frictional force as determined by the pin-on-disk experimental procedure. As a result, the optimization using RSM successfully interpreted the experimental data, according to the analysis of variance, with coefficients of determination of R2 = 0.91 and adjusted R2 = 0.77. The Coefficient of Friction (CoF) and wear rate were investigated following tribological testing. Castor oil had a lower coefficient of friction than canola and sunflower seed oil, according to the findings. In terms of friction reduction, castor oil surpasses canola and sunflower seed oil.

The Production of Porous Asphalt Mixtures with Damping Noise Reduction and Self-Healing Properties through the Addition of Rubber Granules and Steel Wool Fibers.

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze-thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards.

Design and optimization of a novel porous plate oil–gas separator

In the oil-injection compressor system, it is necessary to separate the lubricating oil by sequentially applying the mechanical separator and the separating filter element, however, the oil–gas separation filter has disadvantages such as short service life, high cost, and great environmental pollution. In this paper, a porous plate separator is proposed to achieve the coalescence of small oil droplets, and then the larger droplets can be removed by mechanical collisions driven by turbulence flow in the separator. This device is designed to be used after the primary separator, in the hope of replacing the separation filter element. The structure of the porous plate oil–gas separator is constructed through the staggered arrangement of two porous plates, and the two-phase flow characteristics in the separator are simulated through the Euler-Lagrangian method with the droplet’s behavior of collision and breakup considered. The hole diameter, hole distance, plate distance, and inlet velocity are the key parameters of the separator, and these parameters are combined through the orthogonal design method to form several different structures and working conditions. The results of range analysis and pressure difference distribution under different layers are analyzed comprehensively, so the best combination is determined in terms of particle size growth rate, oil separation efficiency, and pressure loss. The designed structure is machined, and a test bench is set up, so the performance of the porous plate separator is experimentally tested. It is found that the simulation results are in good agreement with the experimental data, and the best simulated conditions are also verified by the experiment. When the inlet velocity is 0.2 m·s−1, the optimal scheme is suggested as follows: Hole diameter = 1.5 mm; Hole distance = 3 mm; Plate distance = 1 mm; plate layers = 40.

Influence of Nb Doping on the Performance of Oxygen Reduction Reaction on TiO2 in Acidic Environmental

Polymer electrolyte fuel cells (PEFCs) have attracted attention as one of the next-generation power sources that are environmentally friendly. However, the high manufacturer's costs, short service life, and insufficient cell performance are solved to realize widespread commercialization. A non-platinum group metal catalyst is relatively low in cost and highly durable. In particular, the oxides of group 4 and 5 elements were reported to show high oxygen reduction reaction (ORR) activity and durability. Their oxides are considered dominant candidates for the non-platinum group metal catalysts, although they have a fateful flaw that their ORR activity is clearly poorer than traditional platinum-supported carbon catalysts. It was reported that introducing oxygen vacancies and other transition metals into the crystal structure of 4- and 5-group metal oxides effectively enhanced the ORR activity. The active site of 4- and 5-group metal oxides is unclear despite it being well-known that the oxygen vacancies and dopant atoms are related to its ORR activity. It is now indicated that candidates of active site were the oxygen vacancies around the dopant atom and the crystal distortion. However, it is hard to separate their effects because both dopant atoms and oxygen vacancies distort the local crystal structure. On the other hand, identifying the ORR active site leads to obtaining the catalyst design with high ORR activity. We focused on the oxide nanosheet, the simplest structure formed by a six-coordinate octahedral, as the model electrode. The thickness of oxide nanosheets is about 1 nm, and forming a single layer on a substrate is relatively easy. Thus, it was expected that the electron conductivity was guaranteed enough by the tunnel effect. This study employed titanium oxide nanosheets (TiO2ns) as the model catalyst and niobium as a dopant to investigate the effect of dopant atoms on ORR activity. The ratio of Nb/Ti in the prepared model electrode was 0/1, 1/1, and 2/1. In addition, the oxygen vacancies were introduced into all prepared electrodes to study the impact of oxygen vacancies on ORR activity at each Nb/Ti ratio. The thickness of Nb-doped TiO2ns (Nb-TiO2ns) was about 1.2 nm for the 1/1 ratio and slightly thicker for the 0/1 ratio. In contrast, the thickness of the 2/1 ratio of Nb-TiO2ns was about two times thicker than the 1/1 ratio. The thicknesses of Nb-TiO2ns in each ratio were increased by the reduction treatment to introduce the oxygen vacancies. One reason for this thickness increase may be related to the phase transition into the anatase structure. ORR activity was evaluated from the on-set potential of ORR (E ORR) measured at the step scan with 3 minutes step width. E ORR was slightly elevated with Nb doping. The ion radii of Nb and Ti atoms are 3 pm different when it is assumed that both ions are six-coordinated and their valence is Nb5+ and Ti4+. These results showed that the crystal structure distortion probably has a slight but positive effect on ORR activity.After the reduction treatments, the E ORR of the 0/1 ratio of Nb-TiO2ns increased and was the same as that of the 2/1 ratio. The introduction of oxygen vacancies certainly enhanced the ORR activity of the 0/1 ratio of Nb-TiO2ns. The oxygen vacancies are thought to be necessary to enhance the ORR activity, although the reduction condition wasn’t optimized for the Nb-doped samples.From the above results, we consider that the active site is the oxygen vacancy site rather than the crystal distortion site at this time.

Effect of High Polymer, Crumb Rubber, and Epoxy-Modified Asphalt Binders on Laboratory Performance of Open-Graded Friction Course Mixtures

Open-graded friction course (OGFC) is a thin asphalt mixture surface layer. It is gap-graded with a high percentage of coarse aggregates that are nearly uniform in size, resulting in a high percentage of interconnected air voids and asphalt binder, which provides improved skid resistance, visibility, and decreased pavement–tire noise. However, construction personnel at the Louisiana Department of Transportation and Development reported that conventional OGFC mixtures have durability issues and shorter service life, compared with thin asphalt mixture lifts. Hence, effects of different asphalt binder types on the performance of OGFC mixtures were evaluated. Five types of asphalt binder were utilized: conventional styrene-butadiene-styrene (SBS) asphalt binder PG 76-22M; high SBS content asphalt binder PG 88-28; diluted epoxy asphalt (EA) binder with two different dosages (25% and 50%); and a hybrid modified asphalt binder prepared with SBS and crumb rubber modifier PG 76-22G. The optimal aggregate structures were determined based on minimum required air voids and voids in coarse aggregate. Physical and mechanical tests were conducted to assess the performance of OGFC mixtures, including draindown, permeability, loaded wheel track, and Cantabro abrasion loss. Results indicate that OGFC mixtures incorporating diluted EA binder exhibited lower draindown values than mixtures containing PG 76-22M and PG 88-28. Moreover, mixtures with PG 88-28 and 50% EA binders demonstrated improved resistance to rutting. Mixtures with 50% EA and PG 88-28 binders demonstrated improved durability, compared with mixtures with PG 76-22M for unaged and aged conditioning, as measured by Cantabro abrasion loss values.

Exploration on the synergistic effect of antioxidants for coal-to-liquid base oil: From the perspective of oxidation resistance and thermal stability

Coal-to-liquid (CTL) base oil is a high-quality lubricant base oil made from coal. However, its poor oxidation stability and short service life limit its application. Pressurized differential scanning calorimetry and Rotary bomb oxidation test are utilized for the evaluation of oxidation stability. Thermogravimetric analysis is performed for the thermal stability assessment. The results showed the reasonable combination of commercial antioxidants can significantly improve the oxidative and thermal stability of two typical CTL base oils, CTL3 and CTL6. The synergistic mechanism of antioxidants in CTL base oil was studied from the perspective of pyrolysis kinetics and pyrolysis mechanism. For CTL3, adding the compound antioxidant 2,6-di-tert-butyl-4-methylphenol (T501) and n-phenyl-1-naphthylamine (T531) results in an almost eightfold increase in oxidation induction time (OIT) and a 33.4 % increase in activation energy compared to pure CTL3. For CTL6, adding the compound antioxidant dialkyl dithiophosphate (T203) and diphenylamine (L57) results in an almost tenfold increase in OIT and a 10.9 % increase in activation energy compared to pure CTL6. The designed commercial antioxidant compound systems had excellent synergistic effects and the synergistic mechanisms were illustrated.

Experimental study on slurry erosion wear behaviour of 2205 duplex stainless steel through integrated Taguchi approach and artificial neural network

Slurry erosion due to particle entrainment poses a significant threat to slurry handling components, leading to reduced performance and shorter service life. The ferritic-austenitic microstructure of 2205 duplex stainless steel (DSS) offers resistance to erosion and corrosion in harsh environments. This study investigated the slurry erosion wear response of 2205 DSS, focusing on parameters, such as: angle of impingement, impact velocity, slurry concentration, erodent size, and stand-off distance. A Taguchi experimental design approach, along with analysis of variance (ANOVA), was employed to design the experiments and identify the most significant factors. ANOVA results revealed that impact velocity and slurry concentration were the most influential parameters affecting mass loss, while erodent size and impact velocity significantly influenced surface roughness. Additionally, an artificial neural network model was used to estimate output responses, and the model's predictions were compared with experimental results. The surface and sub-surface characteristics of the eroded samples were analysed using X-ray diffraction, microhardness testing, and optical profilometry. The material removal mechanisms were studied using scanning electron microscopy, revealing ductile erosion behaviour in 2205 DSS. Micro-cutting, ploughing, lip formation, and indentation were identified as the primary methods of material removal in 2205 DSS.

Reduction reactions at the interface between CdS quantum dot and Z-type ligands driven by electron injection in the electroluminescent processes.

The efficient and stable electroluminescence of quantum dots (QDs) is of great importance in their applications in new display technologies. The short service life of blue QDs, however, hinders their development and commercialization. Different mechanisms have been proposed for the destabilization of QDs in electroluminescent processes. Based on real-time time-dependent density functional theory studies on the QD models covered by Z-type ligands (XAc2, X = Cd, Zn, Mg), the structural evolution is simulated to reveal the mechanism of the reduction reactions induced by electron injection. Our simulations reproduce the experimental observations that the reduction reactions occur at the QD-ligand interface, and the reduced Cd atom is almost in a zero valence state. However, different sites are predicted for the reactions in which the surface metal atom of the QD instead of the metal atom in the ligands is reduced. As a result, one of the arms of the chelate ligand leaves the QD, which tends to cause damage to its electroluminescent performance. Our findings contribute to a mechanistic understanding of the reduction reactions that occurred at the QD-ligand interface.