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This study aims to explore the synthesis and tribological performances of di-n-octyl sebacate (DOS) synthesized with spherical nano-MoS₂/sericite (SMS) and carboxylated SMS (CSMS) as catalysts.

SMS and CSMS were used as esterification catalysts to synthesize DOS from sebacic acid and n-octanol. The two catalysts were in situ dispersed in the synthesized DOS after the reaction to form suspensions. The tribological performances of the two suspensions after 20 days of storage were studied.

CSMS was more stably dispersed in DOS than SMS, and they reduced friction by 55.6% and 22.2% and wear by 51.3% and 56.5%, respectively. Such results were mainly caused by the COOH on CSMS, which was more conducive to improving the dispersion and friction reduction of CSMS than wear resistance. Another possible reason was the difference between the dispersion amounts of CSMS and SMS in DOS. The sericite of SMS was converted into SiO₂ to enhance wear resistance, while that of CSMS only partially generated SiO₂, and the rest still remained on the surface to reduce friction.

This work provides a more effective SMS catalytical way for DOS synthesis than the traditional inorganic acid catalytical method. SMS does not need to be separated after reaction and can be dispersed directly in DOS as a lubricant additive. Replacing SMS with CSMS can produce a more stable suspension and reduce friction significantly. This work combined the advantages of surface carboxylation modification and in situ catalytic dispersion and provided alternatives for the synthesis of DOS and the dispersion of MoS₂-based lubricant additives.

To improve the corrosion resistance of magnesium alloys, the construction of protective coatings is necessary to extend the service life of Mg-based materials.

SiO₂ nanoparticles modified by dodecyltrimethoxysilane (DTMS) were added to the PP and a superhydrophobic Mg(OH)₂/PP-60mSiO₂ composite coating was fabricated on the surface of AZ31 magnesium alloy via the hydrothermal method and subsequently the immersion treatment.

Hydrophilic SiO₂ nanoparticles become hydrophobic after modified by DTMS, showing a higher dispersibility in xylene. By incorporating modified SiO₂ nanoparticles into the composite PP coating, the hydrophobicity of the layer was enhanced, resulting in a contact angle of 166.3° and a sliding angle of 3.4°. It also improved the water repellency and durability of the coating. Furthermore, the intermediate layer of Mg(OH)₂ significantly strengthened the bond between the PP layer and the substrate. The Mg(OH)₂/PP-60mSiO₂ composite coating significantly enhances the corrosion resistance of the magnesium alloy by effectively blocking the infiltration of the corrosion anions during corrosion. The corrosion current density of the Mg(OH)₂/PP-60mSiO₂ composite coating is approximately 8.23 × 10^–9 A·cm^-2, which can achieve a magnitude three times lower than its substrate, making it a promising surface modification for the Mg alloy.

The composite coating effectively and durably enhances the corrosion resistance of magnesium alloys.

Three-dimensional (3D) casting means using additive manufacturing (AM) techniques to print the mould for casting the cast tool. The printed mould, however, should be checked for its dimensional accuracy. 3D scanning can be used for the same. The purpose of this study is to combine the different AM techniques for 3D casting with 3D scanning to produce parts with close tolerance for preparing electrical discharge machining (EDM) electrodes.

The four processes, namely, stereolithography, selective laser sintering, fused deposition modelling and vacuum casting, are used to print the casting mould. The mould is designed in two halves, assembled to form a complete mould. The mould is 3D scanned in two stages: before and after using it as a casting mould. The mould's average and maximum dimensional deviations are calculated using 3D-scanned results. The eutectic Sn-Bi alloy is cast in the mould. The surface roughness of the mould and the cast tool are measured.

The cast tool is selected from the four processes in terms of dimensional accuracy and surface finish. The same is electroplated with copper. The microstructure of the cast tool (low-melting-point alloy) and deposited copper is analysed using a scanning electron microscope. Energy dispersive spectroscopy and X-ray diffraction techniques are used to verify the composition of the cast and coated alloy. The electroplated tool is finally tested on the EDM setup. The material removal rate and tool wear are measured. The performance is compared with a solid copper tool. The free-form customised EDM mould is also prepared, and the profile is cast out. The same is tested on the EDM. Thus, the developed path can be successfully used for rapid tooling applications.

The eutectic composition of Sn-Bi is cast in the 3D-printed mould using different AM techniques combined with 3D scanning quality to check its feasibility as an EDM electrode, which is a novel work and has not been done previously.

The purpose of this paper was to prepare a ternary hierarchical rough particle to accelerate the anti-corrosive design for coastal concrete infrastructures.

A kind of micro-nano hydrophobic ternary microparticles was fabricated from SiO₂/halloysite nanotubes (HNTs) and recycled concrete powders (RCPs), which was then mixed with sodium silicate and silane to form an inorganic slurry. The slurry was further sprayed on the concrete surface to construct a superhydrophobic coating (SHC). Transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings demonstrate that the nano-sized SiO₂ has been grafted on the sub-micron HNTs and then further adhered to the surface of micro-sized RCP, forming a kind of superhydrophobic particles (SiO₂/HNTs@RCP) featured of abundant micro-nano hierarchical structures.

The SHC surface presents excellent superhydrophobicity with the water contact angle >156°. Electrochemical tests indicate that the corrosion rate of mild steel rebar in coated concrete reduces three-order magnitudes relative to the uncoated one in 3.5% NaCl solution. Water uptake and chloride ion (Cl^-) diffusion tests show that the SHC exhibits high H₂O and Cl^- ions barrier properties thanks to the pore-sealing and water-repellence properties of SiO₂/HNTs@RCP particles. Furthermore, the SHC possesses considerable mechanical durability and outstanding self-cleaning ability.

SHC inhibits water uptake, Cl^- diffusion and rebar corrosion of concrete, which will promote the sustainable application of concrete waste in anti-corrosive concrete projects.

Field-effect transistor (FET) has excellent electronic properties and inherent signal amplification, and with the development of nanomaterials technology, FET biosensors with nanomaterials as channels play an important role in the field of heavy metal ion detection. This paper aims to review the research progress of silicon nanowire, graphene and carbon nanotube field-effect tube biosensors for heavy metal ion detection, so as to provide technical support and practical experience for the application and promotion of FET.

The article introduces the structure and principle of three kinds of FET with three kinds of nanomaterials, namely, silicon nanowires, graphene and carbon nanotubes, as the channels, and lists examples of the detection of common heavy metal ions by the three kinds of FET sensors in recent years. The article focuses on the advantages and disadvantages of the three sensors, puts forward measures to improve the performance of the FET and looks forward to its future development direction.

Compared with conventional instrumental analytical methods, FETs prepared using nanomaterials as channels have the advantages of fast response speed, high sensitivity and good selectivity, among which the diversified processing methods of graphene, the multi-heavy metal ions detection of silicon nanowires and the very low detection limit and wider detection range of carbon nanotubes have made them one of the most promising detection tools in the field of heavy metal ions detection. Of course, through in-depth analysis, this type of sensor has certain limitations, such as high cost and strict process requirements, which are yet to be solved.

This paper elaborates on the detection principle and classification of field-effect tube, investigates and researches the application status of three kinds of FET biosensors in the detection of common heavy metal ions. By comparing the advantages and disadvantages of each of the three sensors in practical applications, the paper focuses on the feasibility of improvement measures, looks forward to the development trend in the field of heavy metal detection and ultimately promotes the application of field-effect tube development technology to continue to progress, so that its performance continues to improve and the application field is constantly expanding.

This study aims to research the time-varying mesh stiffness (TVMS) model for orthogonal face gear drives considering elastohydrodynamic lubrication (EHL) and provide a theoretical basis for understanding the dynamic characteristics of face gear drives.

Considering EHL, a novel model is proposed to calculate the TVMS of orthogonal face gears using the deformation compatibility condition. First, the tooth surface equations of orthogonal face gears are derived according to the tooth surface generation principle. Then, the oil film thickness on the tooth surface of face gears is obtained by solving the governing equations of EHL. Furthermore, the proposed model is used to calculate the TVMS of face gears along the mesh cycle and is verified. Finally, the effects of module, tooth number of shaper cutter and pressure angle on mesh stiffness are analyzed.

The results indicate that when the contact ratio is greater than 1 and less than or equal to 2, the TVMS of face gears exhibits a phenomenon of double-single tooth alternating meshing where sudden changes occur. As the module increases, the overall mesh stiffness of face gears increases, and the magnitude of the sudden change at the moment of single-double tooth alternating meshing gradually increases. As the tooth number of shaper cutter and pressure angle increase, so does the TVMS of face gears. When the effect of oil film is considered, the calculated TVMS of face gears slightly increases overall and the increase in average oil film thickness leads to a rise in the TVMS. This study provides a theoretical basis for understanding the dynamic characteristics of face gear drives.

This study’s originality and value lie in its comprehensive approach, which includes conducting analysis based on loaded tooth contact, considering the influence of elastohydrodynamic lubrication, proposing a novel analytical–finite–element model, calculating TVMS of face gears, verifying the proposed model and analyzing the effects of typical structural parameters and oil film thickness.

A review of sustainability challenges of flame retardants (FRs) for textiles has been conducted. Specifically, the purpose of this paper is to identify and recommend solutions to sustainability challenges emanating from the raw material, processing technology and performance of the FRs used for textiles.

The approach used in preparing this paper was based on the review of various scholarly databases about the subject matter. The review approach is designed to inform the readers about the sustainability challenges of FRs for textiles. The science of burning and FRs for synthetic and cellulosic fibres were reviewed. Both synthetic and natural biodegradable FRs for textiles has been identified. The obtained literature was then synthesised to get information about sustainable challenges of non-halogenated FRs both synthetic and natural biodegradable. Finally, possible approaches for mitigating the identified challenges have been recommended.

The sustainability challenges of the FRs in terms of raw material, processing, affordability and performance have been identified. Synthetic FRs suffer from sustainability challenges in terms of raw materials, processing and non-renewability. Despite the environmental friendliness and sustainability in terms of being renewability, processability and biodegradability, natural biodegradable FRs have poor performance compared to synthetic ones. Moreover, natural biodegradable FRs depend on geographical condition and lack economic variability data. Potentially, the challenges of FRs can be mitigated through eco-friendly synthesis, chemical modification and sustainable methods of applications. Because of its renewability and environmental friendliness, biodegradable FRs have a potential to becoming sustainable if researched more.

In this review, a collection of literature about sustainability challenges of FRs and the approaches to overcome the challenges has been provided. The collected information was analysed and synthesised to bring understanding of the science of burning, types and application of FRs for textiles and biodegradable FRs. Sustainability challenges have been identified, and mitigation approaches are provided.

Productivity is often cited as a key barrier to the adoption of metal laser-based powder bed fusion (ML-PBF) technology for mass production. Newer generations of this technology work to overcome this by introducing more lasers or dramatically different processing techniques. Current generation ML-PBF machines are typically not capable of taking on additional hardware to maximise productivity due to inherent design limitations. Thus, any increases to be found in this generation of machines need to be implemented through design or adjusting how the machine currently processes the material. The purpose of this paper is to identify the most beneficial existing methodologies for the optimisation of productivity in existing ML-PBF equipment so that current users have a framework upon which they can improve their processes.

The review method used here is the preferred reporting items for systematic review and meta-analysis (PRISMA). This is complemented by using an artificial intelligence-assisted literature review tool known as Elicit. Scopus, WEEE, Web of Science and Semantic Scholar databases were searched for articles using specific keywords and Boolean operators.

The PRIMSA and Elicit processes resulted in 51 papers that met the criteria. Of these, 24 indicated that by using a design of experiment approach, processing parameters could be created that would increase productivity. The other themes identified include scan strategy (11), surface alteration (11), changing of layer heights (17), artificial neural networks (3) and altering of the material (5). Due to the nature of the studies, quantifying the effect of these themes on productivity was not always possible. However, studies citing altering layer heights and processing parameters indicated the greatest quantifiable increase in productivity with values between 10% and 252% cited. The literature, though not always explicit, depicts several avenues for the improvement of productivity for current-generation ML-PBF machines.

This systematic literature review provides trends and themes that aim to influence and support future research directions for maximising the productivity of the ML-PBF machines.

The purpose of this study is to investigate the influence of varying concentrations of nano-SiO₂ particle doping on the structure and properties of the micro-arc oxidation (MAO) coating of 7075 aluminum alloy. This research aims to provide novel insights and methodologies for the surface treatment and protection of 7075 aluminum alloy.

The surface morphology of the MAO coating was characterized using scanning electron microscope. Energy spectrometer was used to characterize the elemental content and distribution on the surface and cross section of the MAO coating. The phase composition of the MAO coating was characterized using X-ray diffractometer. The corrosion resistance of the MAO coating was characterized using an electrochemical workstation.

The results showed that when the addition of nano-SiO₂ particles is 3 g/L, the corrosion resistance is optimal.

This study investigated the influence of different concentrations of nano-SiO₂ particles on the structure and properties of the MAO coating of 7075 aluminum alloy.

Ascorbic acid, a water-soluble antioxidant, is an essential component of the human diet and is known for its potent antioxidant properties against several diseases. In recent years, there has been increasing interest in the development of nonenzymatic sensors due to their simplicity, efficiency and excellent selectivity. The aim of this study is to present a selective and sensitive method for the detection of ascorbic acid in aqueous system using a new electrochemical non-enzymatic sensor based on a gold nanoparticles Au-NPs-1,3-di(4-bromophényl)-5-tert-butyl-1,3,5-triazinane (DBTTA) composite.

Using the square wave voltammetry (SWV) technique, a series of Au-NPs-DBTTA composites were successfully developed and investigated. First, DBTTA was synthesized via the condensation of tert-butylamine and a4-bromoaniline. The structure obtained was identified by IR, 1H NMR and 13C NMR analysis. A glassy carbon electrode (GCE) was modified with 10–1 M DBTTA dissolved in an aqueous solution by cyclic voltammetry in the potential range of 1–1.4 V. Au-NPs were then deposited on the DBTTA/GCE by a chronoamperometric technique. SWV was used to study the electrochemical behavior of the modified electrode (DBTTA/Au-NPs/GCEs). To observe the effect of nanoparticles, ascorbic acid in a buffer solution was analyzed by SWV at the modified electrode with and without gold nanoparticles (Au-NPs).

The DBTTA/Au-NPs/GCE showed better electroanalytical results. The detection limit of 10–5 M was obtained and the electrode was proportional to the logarithm of the AA concentration in the range of 5 × 10⁻³ M to 1 × 10⁻¹ with very good correlation parameters.

It was also found that the elaborated sensor exhibited reproducibility and excellent selectivity against interfering molecules such as uric acid, aspartic acid and glucose. The proposed sensor was tested for the recognition of AA in orange, and satisfactory results were obtained.