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AbstractThis paper presents a novel capacitive microelectromechanical system comprising an array of elastomeric micro-pillars, which has been developed through the introduction of a coupled set of three nonlinear equations. The results have demonstrated that the new model utilizing polydimethylsiloxane is effective in reducing the actuation voltage, although this efficiency is reduced when the temperature is decreased. Moreover, the impact of frequency-dependent permittivity and its relaxation time on the vibrations of the moving electrode has been examined. The provided model and procedure can be utilized to analyze the effects of other materials on the system’s performance and to enhance its sensitivity. [ABSTRACT FROM AUTHOR]

In this study, an aging asphalt mixture was regenerated by a waste-based rejuvenator and cemented by solid waste-based solidification materials (SSMs). A splitting test, wheel tracking test, and three-point bending test were conducted to evaluate the properties of the regenerated asphalt mixture (RAM). The results reveal that the properties of the asphalt mixture were not diminished or were moderately enhanced by the 30% substitution of RAP. With the substitution of RAP to 100%, the splitting tensile strength, dynamic stability, and splitting strength ratio were decreased by 13%, 15%, and 5%, respectively. With the 100% substitution of SSMs for cement, the compressive strength, dynamic stability, flexural strain, and splitting strength ratios of the RAM were increased by 40%, 32%%, 14%, and 8%, respectively. The lightweight components can be supplemented, and low-temperature deformation and interlayer flowability can be improved by the incorporation of the rejuvenator. The generation of hydrated calcium silicate and ettringite for SSMs is greater than those of cement. The massive generation of ettringite has been observed to increase the solid phase volume by 120%, which may facilitate a more complete filling of the remaining pores in the RAM due to water evaporation. The regeneration and cement on green and the high performance of the rejuvenator and the SSM markedly enhanced RAM performance. [ABSTRACT FROM AUTHOR]

The microchannel plate (MCP) is an electron multiplier with millions of micro through-holes that must withstand strong vibrations and enormous shocks in spaceborne detectors. To ensure the reliability and robustness of the MCP in space applications, we proposed an equivalent mechanical model of the MCP to investigate its mechanical properties, since the direct creation of the finite element model using the finite element method (FEM) is not feasible. Then, we developed a test system to verify the effectiveness of the equivalent mechanical model. The results show that the error of harmonic response analysis and the test result is less than 10 %, which is acceptable. Finally, we conducted parametric studies of the MCPs and obtained the equivalent mechanical model of the MCPs with different geometric parameters. This study will help researchers to optimize the MCP for aerospace-grade detectors. [ABSTRACT FROM AUTHOR]

Implementation of existing stress–strain models for cold-formed steel requires the input of key material parameters determined from corner coupon tests on cold-formed portions. This paper proposes various approaches that can accurately describe the stress–strain responses of cold-formed steel by using corner material properties if known, or by using parent material properties and the corner geometry after cold-forming in the absence of corner material properties. First, a comprehensive database of coupon test results of cold-formed steel is assembled. A total of 483 corner coupon test results with 236 full stress–strain curves are collected from 31 sources, covering a large range of steel grades with nominal yield strength varying from 235 to 960 MPa. The applicability of existing empirical models for determination of the enhanced yield strength, ultimate strength, and ultimate strain is carefully evaluated. New predictive expressions for the required input parameters (namely, 0.01% or 0.05% proof stresses for the use of the two-stage Ramberg-Osgood model, and the strain hardening exponent for the use of one-stage material model) are subsequently derived. Prediction performances of the two-stage Ramberg-Osgood model and the one-stage material model are then evaluated against experimental stress–strain curves under different availabilities of primary material parameters. According to the proposed approaches, the minimum required input parameter to utilize these models is only the yield strength of cold-formed steel or, alternatively, the yield strength of the parent metal and corner geometry after cold-forming. The developed models are proved to be accurate in predicting the monotonic stress–strain response (up to the ultimate point) of cold-formed steel, and they are suitable for use in parametric studies and advanced modeling of cold-formed structures. [ABSTRACT FROM AUTHOR]

The processing of long glass fibre-reinforced thermoplastics results in considerable fibre damage, particularly during plasticising. By using thermoplastic foam injection moulding (FIM) with a constant blowing agent atmosphere, fibre damage during plasticisation can be reduced. This can be attributed to the reduction of the melt viscosity on the one hand and the influence of the melting behaviour on the other. Therefore, the influence of the FIM and the process parameters on the fibre length and the fibre length distribution are analysed and compared with the influence of the process parameters on the melt viscosity. [ABSTRACT FROM AUTHOR]

AbstractThe simulation of the aortic valve (AV) remains challenging due to its geometric complexity and the multi-physics nature of the problem. In this study, we utilized COMSOL to establish a three-dimensional, three-leaflet AV fluid-structure interaction model and investigated the influence of material properties on the valve's mechanical behavior in a healthy state. The results indicated that variations in the aortic wall material model had a minor impact on AV hemodynamics. Additionally, while the linear elastic properties of the leaflets limit valve opening and closing, this material model allows for rapid assessment of AV performance within the range of material deformation. [ABSTRACT FROM AUTHOR]

Palm leaves are an important carrier for written heritage in southwest China, Tibet, and India. Due to the very nature of the material, many ancient palm leaf manuscripts are facing acidification and other types of degradation. Therefore, scientific research and conservation are of utmost importance. To study material properties and aging mechanisms of palm leaf manuscripts, their basic composition, physical and chemical properties, we studied infrared spectra, internal microstructure, and changes within the structure before and after aging of commonly used local talipot leaves. The results show that aging and deterioration of talipot leaves are mainly due to their acidic production process and high lignin content. The uneven distribution of longitudinal and transverse fiber bundles makes talipot leaves prone to longitudinal splitting. These findings provide important references for the conservation and long-term preservation of palm leaf manuscripts. [ABSTRACT FROM AUTHOR]

Light detection and ranging (LIDAR) sensors using a polarization-diverse receiver are able to capture polarimetric information about the target under measurement. We demonstrate this capability using a silicon photonic receiver architecture that enables this on a shot-by-shot basis, enabling polarization analysis nearly instantaneously in the point cloud, and then use this data to train a material classification neural network. Using this classifier, we show an accuracy of 85.4% for classifying plastic, wood, concrete, and coated aluminum. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) have drawn significant attention due to their unique design and superior mechanical properties. Comprising 5–35 at% of five or more elements with similar atomic radii, HEAs exhibit high configurational entropy, resulting in single-phase solid solutions rather than intermetallic compounds. Additive manufacturing (AM), particularly direct energy deposition (DED), is effective for producing HEAs due to its rapid cooling rates, which ensure uniform microstructures and minimize defects. These alloys typically form face-centered cubic (FCC) or body-centered cubic (BCC) structures, contributing to their exceptional strength, hardness, and mechanical performance across various temperatures. However, FCC-structured HEAs often have low yield strengths, posing a challenge for structural applications. In this study, a Ni-Co-Fe-Cr-Al-Ti HEA was manufactured using the DED method. This study proposes that the addition of aluminum and titanium creates a γ + γ′ phase structure within a multicomponent FCC-HEA matrix, enhancing the thermal stability and coarsening the resistance and strength. The γ′ phase with an ordered FCC structure significantly improves the mechanical properties. Analysis confirmed the presence of the γ + γ′ structure and demonstrated the alloy's high tensile strength and microhardness. This approach underscores the potential of AM techniques in advancing HEA production for high-performance applications. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the mechanical behavior of resin composites and hybrid glass ionomer cement in class I adhesive dental restorations under loading and shrinkage conditions. Three CAD models of a mandibular first molar with class I cavities were created and restored with different techniques: a bi-layer of Equia Forte HT with Filtek One Bulk Fill Restorative composite (model A), a single layer of adhesive and Filtek One Bulk Fill Restorative (model B), and a single layer of Equia forte HT (model C). Each model was exported to computer-aided engineering software, and 3D finite element models were created. Models A and B exhibited a similar pattern of stress distribution along the enamel–restoration interface, with stress peaks of 12.5 MPa and 14 MPa observed in the enamel tissue. The sound tooth, B, and C models showed a similar trend along the interface between dentine and restoration. A stress peak of about 0.5 MPa was detected in the enamel of both the sound tooth and B models. Model C showed a reduced stress peak of about 1.2 MPa. A significant stress reduction in 4 mm deep class I cavities in lower molars was observed in models where non-shrinking dental filling materials, like the hybrid glass ionomer cement used in model C, were applied. Stress reduction was also achieved in model A, which employed a bi-layer technique with a shrinking polymeric filling material (bulk resin composite). Model C's performance closely resembled that of a sound tooth. [ABSTRACT FROM AUTHOR]

Three-dimensional printing is ideally suited to produce unique and complex shapes. In this study, the material properties of polysiloxanes, commonly named silicones, produced additively by two different methods, namely, multi-jet fusion (MJF) and material extrusion (ME) with liquid printing heads, are investigated. The chemical composition was compared via Fourier-transform infrared spectroscopy, evolved gas analysis mass spectrometry, pyrolysis gas chromatography coupled to mass spectrometry, and thermogravimetry (TGA). Density and low-temperature flexibility, mechanical properties and crosslink distance via freezing point depression were measured before and after post-treatment at elevated temperatures. The results show significant differences in the chemical composition, material properties, as well as surface quality of the tested products produced by the two manufacturing routes. Chemical analysis indicates that the investigated MJF materials contain acrylate moieties, possibly isobornyl acrylate linking branches. The hardness of the MJF samples is associated with crosslinking density. In the ashes after TGA, traces of phosphorus were found, which could originate from initiators or catalysts of the curing process. The ME materials contain fillers, most probably silica, that differ in their amount. It is possible that silica also plays a role in the processing to stabilize the extrusion strand. For the harder material, a higher crosslink density was found, which was supported also by the other tested properties. The MJF samples have smooth surfaces, while the ME samples show grooved surface structures typical for the material extrusion process. Post-treatment did not improve the material properties. In the MJF samples, significant color changes were observed. [ABSTRACT FROM AUTHOR]

The research aimed to develop aluminum roofing sheets utilizing waste beverage cans, with a focus on minimizing costs and energy consumption. This initiative adhered to ASTM and ISO standard measures and procedures. Waste beverage cans underwent analysis and were compared with control sheets. Subsequently, they were manually melted, alloyed, and cast before being rolled to achieve the desired thickness and enhance specific properties. The resulting sheets were then corrugated. Upon analysis, the produced aluminum sheets exhibited promising characteristics. The corrosion penetration rate was measured at 0.045mm/yr, with a Rockwell hardness number of 55.1 and an indentation depth of 0.1498mm. Moreover, the average impact strength stood at 2.05, with a tensile strength of 71.69Mpa, yield strength of 25.65Mpa, and young modulus of 2596.43Mpa. The findings indicated a significant enhancement in the properties of the aluminum sheets manufactured from waste beverage cans. This underscored the feasibility of utilizing such cans in producing aluminum roofing sheets. Based on the results, it is recommended to further explore and refine the manufacturing process for aluminum roofing sheets from waste beverage cans. Additionally, continued adherence to ASTM and ISO standards is essential for ensuring product quality and reliability.

Power electronic conversion systems introduce different types of voltage stresses on high-voltage epoxy cast insulation in medium-frequency transformers (MFTs), which challenges the reliability of MFTs. The endurance of epoxy insulation at different voltages (AC, DC and pulse) and environmental (thermal and humidity) stresses was studied using encapsulated electrodes in the absence of partial discharge. To assess aging processes and select aging state indicators, various tests including AC breakdown strength (BDE), broadband dielectric spectroscopy, small-angle x-ray scattering (SAXS), Fourier-transform infrared spectroscopy and differential scanning calorimetry (DSC) were first conducted on aged flat samples. The increase of mesoscopic free volume from the SAXS result and local densification (physical aging) of epoxy network from the DSC result were both found. BDE is proved to be sensitive to various aging conditions and thus determined as a test method for encapsulated samples. It is found that the physical aging effect under thermal stress at early aging stages can cause a reversible increase in BDE compared to non-aged samples. This effect can be erased by coupled medium-low electrical stress during aging. In contrast, a sufficiently high electric field will deepen the physical aging extent. Occasional sample failures were observed simultaneously within this process. According to the SAXS and DSC results on flat samples, the failure of encapsulated samples is possibly attributed to the chain fracture around increased mesoscopic free volume during electron bombardment and microcracks generated by interfacial stress release during physical aging. At longer aging periods, the volumetric absorption and diffusion of chemical reactants (oxygen and water) in epoxy networks at high temperatures determines the eventual decrease in BDE, which can be accelerated by the electric field. Ages with different voltage types were gauged by the reduction of BDE compared to pure environmental stress. Bipolar pulses bring heavier aging effects than ACs at the same RMS value. However, the DC component has opposite effects on the BDE with and without thermal stress. [ABSTRACT FROM AUTHOR]

Pyrolysis models are used in the fire science field to simulate the thermal decomposition of materials. These models require knowledge of the kinetic and thermodynamic parameters of an assumed reaction mechanism, and the thermophysical properties of the virgin material and product species. Standard test methods exist for measuring the thermal conductivity of nonreactive materials, but to date no suitable method exists that is compatible with contemporary pyrolysis models and is applicable to thermally reactive materials. In the present study, a modified methodology was presented and evaluated to address this need. The methodology involves a preliminary assessment of thermal stability, followed by a series of tests including: thermogravimetric analysis, differential scanning calorimetry, and laser flash analysis. Once a reaction mechanism has been identified, gram‐scale samples of the virgin and stable product species are isolated and independent measurements of thermal conductivity of those species are obtained. The methodology was applied to eucalyptus fiber hardboard, for which a complete set of property data for pyrolysis modeling was obtained. A pyrolysis experiment was then conducted, and that experiment was simulated using a pyrolysis model parameterized with the measured property data. Model predictions of the mass loss rate and temperature rise of a hardboard sample exposed to radiant heat flux of 35 and 60 kW m−2 were found to be a good match to measurements. These results demonstrate the suitability of the property data, the pyrolysis model, and the utility of this approach. This work will serve as a basis for property determination in future pyrolysis studies. [ABSTRACT FROM AUTHOR]

Many insect species have found their way into ageing research as small and easy-to-keep model organisms. A major sign of ageing is the loss of locomotory functions due to neuronal disorders or tissue wear. Soft and pliable attachment pads on the tarsi of insects adapt to the substrate texture to maximize their real contact area and, thereby, generate attachment during locomotion. In the majority of stick insects, adhesive microstructures covering those pads support attachment. Stick insects do not molt again after reaching the imaginal stage; hence, the cuticle of their pads is subject to continuous ageing. This study aims to quantify how attachment ability changes with age in the stick insect Sungaya aeta Hennemann, 2023 and elucidate the age effects on the material and microstructure of the attachment apparatus. Attachment performance (adhesion and friction forces) on substrates with different roughnesses was compared between two different age groups, and the change of attachment performance was monitored extending over a larger time frame. Ageing effects on the morphology of the attachment pads and the autofluorescence of the cuticle were documented using light, scanning electron, and confocal laser scanning microscopy. The results show that both adhesion and friction forces decline with age. Deflation of the pads, scarring of the cuticle, and alteration of the autofluorescence, likely indicating stiffening of the cuticle, were observed to accumulate over time. This would reduce the attachment ability of the insect, as pads lose their pliant properties and cannot properly maintain sufficient contact area with the substrate.

Mulch was prepared using composted sugarcane leaves, with polyvinyl alcohol and cationic starch as adhesives, through compression molding. The study aimed to investigate the effects of different adhesives on the mechanical properties, thermal oxidative degradation performance, and biodegradability of the covering materials. The results indicated that, when the adhesive dosage was consistent, cover material A, which utilized polyvinyl alcohol as the adhesive, exhibited higher tensile strength and elongation at break compared to cover material B, which employed a blend of polyvinyl alcohol and cationic starch. Specifically, at an adhesive dosage of 20%, cover material A achieved a tensile strength of 0.46 MPa and an elongation at break of 7.72%, representing the highest values among all experimental groups. There was minimal disparity in the thermal oxidative degradation performance between materials prepared with either adhesive; however, a higher quantity of adhesive led to decreased biodegradability performance. After being buried in soil for 120 days, the degradation exceeded 40% for both materials, resulting in loss of their original shape and strength properties. In conclusion, while sugarcane leaves-based biodegradable materials demonstrate favorable degradation performance, further enhancements are necessary to improve their mechanical properties. These materials have potential applications as substitutes for plastic mulch.

The pivot jewel bearing is an important node of some classes of industrial equipment; at nominal operating modes, the speed of relative rotation of the contact surfaces can reach 103 revolutions per second, while the operating time can be measured in years; under such conditions, it is necessary to take into account the wear of the contact surfaces; in this paper, a technique for modeling the dry friction wear of a fast-rotating support pair is proposed, taking into account changes in the properties of materials due to surface heating, based on solving the wear contact problem in a stationary formulation using Archard’s law; the effect of taking into account the temperature dependence of material properties in wear modeling process is demonstrated.

Combination of metal matrix materials with carbon quantum dots (CQDs) can not only optimize the property of metal matrix materials, but also produce novel material systems with ultra-high performance or superior comprehensive performance. The excellent electrical, mechanical, and thermal characteristics of CQDs can compensate for some intrinsic defects of the metal matrices to improve the composite properties. The various interfaces formed through the different degrees of CQDs dispersion in the metal matrices are essential in the mechanism of the composite performance improvement. In this review, the research progress and results of CQDs in metal matrix composites are discussed and summarized, including the recent preparation methods of CQDs and carbon nanostructure-reinforced metal matrix materials, as well as the influences of the preparation methods on the material structures and properties. In addition, by focusing on the interfaces between CQDs and metal matrices in composite materials, the performance improvement and reinforcement mechanisms of the CQD-modified metal matrix composites are described from mechanical, electrical, and thermal aspects. Further studies on CQDs in metal matrix composites are still required to provide theoretical guidance for the preparation of CQDs-reinforced metal matrix composites with intensity and ductility above the average.

Lattice vibrations or phonons play an important role in determining material properties, including thermal conductivity. To model the phenomenon accurately and efficiently, the most important factors governing phonon physics need to be identified, for example, polarization branches. Research continues into many aspects of the fundamental physical processes involved in phonons and into possible applications of these processes in modern physics. One of the most interesting controversies in the thermal properties of graphene involves the importance of out-of-plane acoustic phonons. The need for clarity in understanding this importance dictates that the thermal conductivity of graphene should be evaluated in various circumstances. The nanoscale heat conduction properties of graphene are studied by iteratively solving the Boltzmann transport equation and rigorously treating the normal and Umklapp collisions in the frame of three-phonon interactions. This captures the mechanistic aspects of thermal conductivity by revealing what phonon branches are present. The thermal conductivity is evaluated in different crystallite sizes and at different frequencies and temperatures. The results indicated that out-of-plane acoustic phonons become increasingly important in the frame of three-phonon interactions. The out-of-plane acoustic branch dominates thermal transport whereas the other acoustic branches make small contributions. The importance of this branch is generally attributed to the high density of states and restrictions governing anharmonic effects. The three-phonon normal and Umklapp processes must be clearly accounted for and the contribution from optical branches is not negligible at higher temperatures. The results have implications in the quest for predictive and quantitative calculations of thermal conductivity. [ABSTRACT FROM AUTHOR]

Concrete production faces challenges due to the depletion of natural sand and the need for more sustainable practices. This study investigates the use of sugarcane bagasse ash (SCBA) and recycled polyethylene terephthalate (RPET) as partial replacements for cement and sand, respectively. SCBA was tested as a 5%, 10%, and 15% replacement by weight of cement, while RPET was used as a 5%, 10%, 15%, and 20% substitute for sand by volume. Concrete samples were cured in water for 7, 28, and 56 days. The mix with 5% SCBA and 10% RPET showed comparable compressive strength to conventional concrete and improved split tensile strength by 1.2% and 11.61% at 28 and 56 days, respectively. The compressive strength-to-weight ratio of this blend was less than 3% lower than conventional concrete. This combination also maintained similar water absorption and fire resistance characteristics. These results suggest that 5% SCBA and 10% RPET are effective in enhancing the sustainability of concrete while maintaining structural performance, contributing to more environmentally friendly construction practices. [ABSTRACT FROM AUTHOR]

This review comprehensively addresses the developments and applications of polymer materials in optoelectronics. Especially, this review introduces how the materials absorb, emit, and transfer charges, including the exciton–vibrational coupling, nonradiative and radiative processes, Förster Resonance Energy Transfer (FRET), and energy dynamics. Furthermore, it outlines charge trapping and recombination in the materials and draws the corresponding practical implications. The following section focuses on the practical application of organic materials in optoelectronics devices and highlights the detailed structure, operational principle, and performance metrics of organic photovoltaic cells (OPVs), organic light-emitting diodes (OLEDs), organic photodetectors, and organic transistors in detail. Finally, this study underscores the transformative impact of organic materials on the evolution of optoelectronics, providing a comprehensive understanding of their properties, mechanisms, and diverse applications that contribute to advancing innovative technologies in the field. [ABSTRACT FROM AUTHOR]

Cu–Be alloys are renowned for their exceptional mechanical and electrical properties, making them highly sought after for various industrial applications. This study presents a comprehensive approach to predicting the compositions of various types of Cu–Be alloys, integrating a Random Forest Regressor within a machine learning (ML) framework to analyze an extensive dataset of chemical and thermo-mechanical parameters. The research process incorporated data preprocessing, model training and validation, and robust analysis to discern feature significance. Cluster analysis was also conducted to illuminate the data's intrinsic groupings and to identify underlying metallurgical patterns. The model's predictive power was confirmed by high R2 values, indicative of its capability to capture and explain the variance in the dataset for both testing (R2 = 0.99375) and training (R2 = 0.99858). Distinct groupings within the alloy data were uncovered, revealing significant correlations between composition, processing conditions, and alloy properties. The findings underscore the potential of ML techniques in advancing the material design and optimization of Cu–Be alloys, providing valuable insights for the field of material science. [ABSTRACT FROM AUTHOR]

The terahertz (THz) region of the electromagnetic spectrum, spanning from 0.1 to 10 THz, offers unique opportunities for imaging, spectroscopy, and communication applications. However, the potential of THz technologies has been limited by the availability of efficient and versatile THz emitters. Spintronic THz emitters (STEs), leveraging the ultrafast dynamics of electron spins in magnetic materials, have emerged as a promising solution to this challenge. STEs offer significant advantages, including broad bandwidth, high power output, and room-temperature operation, positioning them at the forefront of THz technology development. Despite these advances, understanding the operational principles and improving the performance of STEs remain areas of active research. This review focuses on the theoretical models that describe the behavior of STEs, aiming to provide a comprehensive overview of the underlying physics and suggest directions for future enhancements. Through a detailed examination of these models, the review seeks to clarify the basics of the physics driving STE performance and highlight innovative strategies for their optimization and application expansion. [ABSTRACT FROM AUTHOR]

By combining the formability of injection-molded polymers with a wide range of metal options, metal injection molding (MIM) allows for manufacturing metallic components with small dimensions and complex geometries. However, steels produced through this process often exhibit higher porosity compared to conventional methods. This article aims to fill this gap by developing a thermochemical oxynitrocarburizing treatment cycle applied to the austenitic stainless steel Catamold 316L. The developed treatment analyzes the diffusion kinetics, mechanical properties, and metallurgical behavior. The oxynitrocarburizing treatment was carried out at a temperature of 570 °C for varying durations of 30, 60, and 120 min. The findings showed that surface microhardness significantly increased, and corrosion resistance improved due to the ceramic behavior of the Epsolon composite and the formation of magnetite, compared to the sintered material. The study reveals a substantial rise in residual compressive stresses of up to − 2790 MPa on the sample surface. The residual stress values and the elevated surface microhardness are highly beneficial for improving the tribological properties of Catamold 316L steel produced by the MIM process. The study suggests that using ionic oxynitrocarburizing in salt baths presents an alternative to plasma processes for treating Catamold 316L steel, providing improved diffusion of nitrogen and carbon. [ABSTRACT FROM AUTHOR]

Vinyl polymers, crucial in contemporary contact lens design, present unique attributes with promising implications for vision correction. This comprehensive review navigates the trajectory and future trajectories of vinyl polymer‐based contact lenses. The introduction underscores the vital role of contact lenses in vision correction and positions vinyl polymers as ideal materials due to their exceptional properties. Delving into material specifics—high oxygen permeability, optical clarity, surface wettability, and mechanical strength—the analysis emphasizes their influence on corneal health, comfort, and durability. The versatility of manufacturing techniques, encompassing spin casting, molding processes, polymerization, and surface modification, underscores their feasibility in crafting high‐quality lenses. Examining clinical applications, encompassing daily disposables, extended wear, silicone hydrogel, and specialty lenses, alongside biocompatibility assessments and user feedback, provides a nuanced understanding of vinyl polymer‐based lens effectiveness. The article candidly addresses challenges—dehydration, deposits, mechanical stability, and durability—alongside regulatory considerations. Future prospects involve novel formulations, smart materials, bioinspired designs, and noninvasive technologies to amplify comfort and performance. In conclusion, this review distills progress, acknowledges challenges, and charts a sanguine course for vinyl polymer materials in advancing contact lens design, envisioning a future marked by enhanced vision correction technologies. [ABSTRACT FROM AUTHOR]

Purpose: Additive manufacturing (AM) of duplex stainless steels (DSS) is still challenging in terms of simultaneously generating structures with high build quality and adequate functional properties. This study aims to investigate comprehensive process-material-property relationships resulting from both laser-directed energy deposition (DED-LB/M) and laser powder bed fusion (PBF-LB/M) of DSS 1.4462 in as-built (AB) and subsequent heat-treated (HT) states. Design/methodology/approach: Cuboid specimens made of DSS 1.4462 were generated using both AM processes. Porosity and microstructure analyses, magnetic-inductive ferrite and Vickers hardness measurements, tensile and Charpy impacts tests, fracture analysis, critical pitting corrosion temperature measurements and Huey tests were performed on specimens in the AB and HT states. Findings: Correlations between the microstructural aspects and the resulting functional properties (mechanical properties and corrosion resistance) were demonstrated and compared. The mechanical properties of DED-LB/M specimens in both material conditions fulfilled the alloy specifications of 1.4462. Owing to the low ductility and toughness of PBF-LB/M specimens in the AB state, a post-process heat treatment was required to exceed the minimum alloy specification limits. Furthermore, the homogenization heat treatment significantly improved the corrosion resistance of DED- and PBF-processed 1.4462. Originality/value: This study fulfills the need to investigate the complex relationships between process characteristics and the resulting material properties of additively manufactured DSS. [ABSTRACT FROM AUTHOR]

Recent studies show that zinc oxide (ZnO) nanostructures have promising potential as an absorbing material. In order to improve the optoelectronic properties of the initial system, this paper considers the process of adsorbing multilayer graphene-like ZnO onto a Si (111) surface. The density of electron states for two- and three-layer graphene-like zinc oxide on the Si (111) surface was obtained using the Vienna ab-initio simulation package by the DFT method. A computer model of graphene-like Zinc oxide on a Si (111)-surface was created using the DFT+U approach. One-, two- and three-plane-thick graphene-zinc oxide were deposited on the substrate. An isolated cluster of Zn3O3 was also considered. The compatibility of g-ZnO with the S (100) substrate was tested, and the energetics of deposition were calculated. This study demonstrates that, regardless of the possible configuration of the adsorbing layers, the Si/ZnO structure remains stable at the interface. Calculations indicate that, in combination with lower formation energies, wurtzite-type structures turn out to be more stable and, compared to sphalerite-type structures, wurtzite-type structures form longer interlayers and shorter interplanar distances. It has been shown that during the deposition of the third layer, the growth of a wurtzite-type structure becomes exothermic. Thus, these findings suggest a predictable relationship between the application method and the number of layers, implying that the synthesis process can be modified. Consequently, we believe that such interfaces can be obtained through experimental synthesis. [ABSTRACT FROM AUTHOR]

Fibres in different textile forms (woven, knitted, stitched, and non-crimp) are used to reinforce composites for multifaced applications, including automotive, aerospace, marine, rail, energy, construction, and defence sectors. Textile fabric-based fibre reinforcements for composites possess some outstanding features, such as good dimensional stability, subtle conformability, deep draw moldability/processability, lightweightness, high strength and stiffness, and low cost. The greatest advantage of textile fibre-reinforced composites is the freedom to tailor their strength and stiffness properties for specific applications. Therefore, the design of composites involves defining the fabric geometry, stacking sequence, and orientation of fibres to optimise the system. Compared to knitted, stitched, and non-crimp fabrics, woven fabric-based fibre-reinforced composites are widely used in the industry. The properties of woven fabric-reinforced composites depend on several factors, such as types of fibre, compositions, polymeric matrices, and fibre/matrix interfacial strength. Some of the advantages are reduced preforming process steps, good impact and delamination resistance, and thermo-mechanical properties. This review has been written to provide detailed information and discussions, including the fabrication processes, relationship between fabric structure and composite properties, and morphological characteristics encompassing the current state-of-the-art in woven fabrics for composite reinforcement. [ABSTRACT FROM AUTHOR]

To improve the machinability properties of CuZn-alloys, these are alloyed with the element lead. Due to its toxicity, a variety of legislative initiatives aim to reduce the lead content in CuZn-alloys, which results in critical machinability problems and a reduction in the productivity of machining processes. Basically, there are two ways to solve the critical machinability problems when machining lead-free CuZn-alloys: optimizing the machinability of lead-free materials on the material side or adapting the processes and the respective process parameters. In this study, the focus is on material-side machinability optimization by investigating the influence of a targeted variation in the process chain in the material production route. To evaluate the influence of the material production route, the brass alloy CuZn40 (CW509L) was produced in four variants by varying the degree of work hardening and the use of heat treatments, and all four variants were evaluated in terms of their machinability. To evaluate the machinability, the cutting force components, the chip temperature, the chip formation, and the chip shape were analyzed. Clear influences of the material production route were identified, particularly with regard to the chip formation mechanisms and the resulting chip shape. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM), a quickly changing field, is reshaping industries by producing novel and customized materials quickly and efficiently. AM deviates from conventional subtractive processes by enabling layer-by-layer production of products with computer-aided design software. This process offers unique advantages for niche applications, such as metamaterial properties. Numerous industries have adopted this adaptable and aesthetically pleasing technology. For 3D printing, nylon, known for its strength, durability, and flexibility, has become the material of choice, especially when creating complex objects. Though it suffers from some difficulties, such as stretching and shrinking, as the most common AM method for nylon, material extrusion takes advantage of its superior mechanical properties and reliability. The processes, morphological traits, and mechanical properties of the AM of nylon and nylon composite materials are all covered in this thorough review, which methodically focuses on the body of current research. Tensile, flexural strength, and hardness are the main mechanical properties explored in this review, considering subtleties found in previous research. The paper ends with a research analysis viewpoint, pointing out managerial and theoretical gaps based on the body of literature and advocating for more studies to improve AM procedures. This succinct but comprehensive review offers insightful guidance on overcoming obstacles and leveraging advances in AM materials. [ABSTRACT FROM AUTHOR]

The development of urbanization and the resulting expansion of residential and transport infrastructures pose new challenges related to ensuring comfort for city dwellers. The emission of transport vibrations and household noise reduces the quality of life in the city. To counteract this unfavorable phenomenon, vibration isolation is widely used to reduce the propagation of vibrations and noise. A proper selection of vibration isolation is necessary to ensure comfort. This selection can be made based on a deep understanding of the material parameters of the vibration isolation used. This mainly includes dynamic stiffness and damping. This article presents a comparison of the method for testing dynamic stiffness and damping using a single degree of freedom (SDOF) system and the method using image processing, which involves tracking the movement of a free-falling steel ball onto a sample of the tested material. Rubber granules, rubber granules with rubber fibers, and rebound polyurethanes were selected for testing. Strong correlations were found between the relative indentation and dynamic stiffness (at 10–60 MN/m3) and the relative rebound and damping (for 6–12%). Additionally, a very strong relationship was determined between the density and fraction of the critical damping factor/dynamic stiffness. The relative indentation and relative rebound measurement methods can be used as an alternative method to measure the dynamic stiffness and critical damping factor, respectively. [ABSTRACT FROM AUTHOR]

Car manufacturers are currently challenged with increasing the sustainability of their products and production to comply with sustainability requirements and legislation. One way to enhance product sustainability is by reducing the carbon footprint of fossil-based plastic parts. Particle foams are a promising solution to achieve the goal of using lightweight parts with minimal material input. Ongoing developments involve the use of expanded particle foam beads made from engineering plastics such as polyamide (EPA). To achieve this, a simulated life cycle was carried out on virgin EPA, including mechanical recycling. The virgin material was processed into specimens using a steam-free method. One series was artificially aged to replicate automotive life cycle stresses, while the other series was not. The mechanical recycling and re-foaming of the minipellets were then carried out, resulting in an EPA particle foam with 100% recycled content. Finally, the thermal and chemical material properties were comparatively analysed. The study shows that the recycled EPA beads underwent polymer degradation during the simulated life cycle, as evidenced by their material properties. For instance, the recycled beads showed a more heterogeneous molecular weight distribution (an increase in PDI from two to three), contained carbonyl groups, and exhibited an increase in the degree of crystallization from approximately 24% to 36%. [ABSTRACT FROM AUTHOR]

This paper defines the tensile properties of a successfully worn 3D-printed transtibial socket. The socket was printed from a proprietary polypropylene filament and FDM 3D-printing process. Fused disposition modeling involves producing successive cross-sectional layers on top of one another and welding them together. Because of this, a notch is formed between the printed layers. As part of this investigation, tensile test specimens were die-cut perpendicular to the material direction and tested according to ASTM D638—Standard Test Method for Tensile Properties of Plastics. From the measured load–elongation data, stress–strain curves and the corresponding material properties were determined, including modulus of elasticity E, Poisson's ratio ν, yield strength Sy, and ultimate strength Su. The average values for each of these material properties were 955 MPa, 0.35, 11.4 MPa, and 16.3 MPa, respectively. In addition to defining tensile properties, this work demonstrated a viable methodology for characterizing the as-built material behavior of 3D-printed sockets. [ABSTRACT FROM AUTHOR]

In the bridge structure, the main bearing element is the spans, which are directly subject to random and continuous loads, environmental influences, ageing, etc. These factors are easy to lead to material deterioration. Therefore, this study proposes a novel approach to investigate the mechanical properties of the material. The span of the bridge is the selected structure for investigation. This study focuses on the general evaluation of mechanical factors consistent with reality, so the following main factors are to be carried out. First, the viscoelastic model of material will be applied to set up and solve the governing differential equation of the beams with material characteristics involving the elastic modulus (E) and the viscous coefficient (C). The viscoelastic model is different from the traditional elastic model due to its non-linearity, reflecting the actual state of the structure. Second, the random vibration signal-based Loss Factor function (LF) calculation using the Power Spectral Density (PSD) to detect changes in structures. LF is a feature representing changes in material properties, including elasticity and viscosity, and is suitable for many types of bridge structures. Also, the paper uses Cubic Interpolation (CI) to generate a surface representing the LF distribution. This interpolation results in surfaces with respect to the LF values distributed by frequencies and spectral amplitudes. Finally, the LF distribution-based material investigation using Convolutional Neural Network (CNN) is proposed with high performance and accuracy. This study applies the proposed method to several bridges in Ho Chi Minh City, Vietnam. It demonstrates that LF is highly suitable for bridge health monitoring. [ABSTRACT FROM AUTHOR]

This comprehensive literature review delves into the application of Scheffe's Simplex Lattice Model for optimizing cement concrete mixtures, with a particular emphasis on its impact on material properties and sustainability. The review meticulously outlines the principles, historical context, and advantages of Scheffe's model, providing a nuanced understanding of its significance. Comparative analyses with traditional and alternative optimization techniques in concrete mix design illuminate the distinct advantages of statistical methods, especially Scheffe's model. The review critically examines the challenges and limitations associated with applying Scheffe's model, addressing issues related to the complexity of concrete mixtures and computational demands. Potential avenues for improvement are explored, suggesting refinements to handle non-linearity, incorporate advanced optimization algorithms, and streamline computational requirements. Additionally, the review highlights emerging trends in statistical modeling for concrete mixture optimization, such as the integration of machine learning and data-driven approaches, signaling the evolving landscape of concrete technology. In conclusion, the literature underscores Scheffe's Simplex Lattice Model as a valuable and versatile tool with far-reaching implications for the advancement of concrete mixture design methodologies. The call to action encourages ongoing research and development to refine the model, explore emerging trends, and address practical challenges, positioning Scheffe's model as a cornerstone in the pursuit of sustainable, resilient, and high-performance concrete materials. [ABSTRACT FROM AUTHOR]

Permeable-pavement design methodologies can improve the hydrologic and therefore the environmental benefits of rural and urban roadway systems. By contrast, conventional impervious pavements perturb the hydrologic cycle, altering the relationship between the rainfall loading and runoff response. Impervious pavements create a hydraulically conductive interface for the transport of traffic-generated chemicals and particulate matter (PM), deleteriously impacting their proximate environments. Permeable-pavement systems are countermeasures to mitigate hydrologic, chemical, and PM impacts. However, permeable pavements are not always equally implementable due to costs, PM loadings, and design constraints. A potential solution to facilitate environmental benefits while meeting the traffic load capacity is the combination of two filtration systems placed at the pavement shoulders and/or pedestrian sidewalks: a bituminous-pavement open-graded friction course (BPFC) and an aggregate-filled infiltration trench. This solution is presented in this manuscript together with the methodological framework and the first results of the investigations into designing and validating such a combined system. The research was conducted at the laboratories of the Polytechnic University of Bari and the University of Florida, while an operational and full-scale physical model was constructed in Bari, Italy. The first results presented characterize the PM deposition on public roads based on granulometry (particle size distributions (PSDs) and particle number densities (PNDs)). Samples (n = 16) were collected and analyzed at eight different sites with different land uses, traffic, and pavements from different cities (Bari and Taranto, Italy). The PM analysis showed similar distributions (PSDs and PNDs), except for two samples. The gravimetric-based PSDs of the PM had granulometric distributions in the sand-size range. In contrast, the PNDs, modeled by a Power Law Model (PLM) (R2 ≥ 0.92), illustrated an exponentially increasing number of particles in the fine silt and clay-size range, representing less than 10% of the PSD mass. Moreover, the results indicate that PM sourced from permeable-pavement systems has differing impacts on the pavement service life. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic interplay between carbon levels and surface area variations on mild steel strength during the rolling process. Focused on understanding the nuanced relationship between these factors and steel durability, the research adopts a systematic approach. Controlled adjustments in carbon levels and surface area variations are employed to assess their impact on the structural integrity and tensile strength of mild steel. Through rigorous analysis and measurement, this study aims to unveil the intricate connections between carbon content, surface area alterations, and steel strength, offering critical insights for optimizing rolling processes in industrial settings. The experimental works have been conducted with carbon levels variations and surface area variations. The samples were tested in two different laboratories, however, the results of two laboratories are almost similar. The higher carbon content increases strength and yield strength varies with different carbon level and surface area. The surface area variations are affected the mechanical properties of mild steel. The maximum stress recorded was 700 MPa and the breaking point observed at 540 MPa. The findings aspire to contribute significantly to refining manufacturing techniques and developing more resilient steel products, thereby advancing our comprehension of material behavior in mechanical applications.

The urgent global challenges of climate change and resource overconsumption highlight the need for sustainable innovations in the construction industry. Ordinary Portland cement, a vital construction material, significantly contributes to carbon emissions. Alkali-activated materials have emerged as promising alternatives. Three-dimensional printing (3DP) has gained attention in construction, because it offers efficiency and sustainability benefits. This study addresses the integration of alkali-activated materials and 3DP, focusing on circular economy implications. This study examines 1200 research articles from the Scopus database and comprehensively reviews 47 articles on 3DP of geopolymer structures. This study identifies critical research gaps, including a lack of focus on 3DP for alkali-activated materials, circular economy models, optimal mixtures, anisotropy mitigation, reinforcement strategies, and scalability. These insights highlight the transformative potential of 3DP with alkali-activated materials in sustainable construction, fostering a circular economy.

The goal of this study was to produce sustainable concrete by reducing reliance on cement, which contributes to high carbon footprints, and natural sand, which is being depleted. Sugarcane bagasse ash (SCBA) was used to partially replace cement at 5 %, 10 %, and 15 %, while recycled polyethylene terephthalate (RPET) was used to partially replace sand at 5 %, 10 %, 15 %, and 20 %. The effects of these substitutions on concrete's mechanical and physical properties were examined after 28 days of water curing. The study observed a decrease in fresh density by 0.36 %–2.67 % with SCBA and RPET inclusion. The slump values ranged between 93 mm and 140 mm, indicating good workability. The reference concrete's compressive strength was 39.65 MPa, while the mix with 5 % SCBA and 10 % RPET achieved 38.23 MPa. This mix also showed a 1.2 % higher split tensile strength than the reference concrete. Although the reference concrete's flexural strength was the highest at 4.56 MPa, all SCBA-RPET mixes remained within 86 % of this value. All modified mixes weighed less than the reference concrete, with the compressive strength-to-weight ratio of the mix with 5 % SCBA and 10 % RPET being closest to the reference mix with only a 2.44 % reduction. These findings suggest that SCBA and RPET can be effectively used to produce sustainable concrete with comparable mechanical properties to conventional concrete.

Nuclear waste control and related equipment play a vital role in safeguarding human health and the environment from the potential dangers of radioactive waste. This study addresses the critical challenge of enhancing the shielding effectiveness of container materials for nuclear waste management, with a focus on comparing the attenuation properties of glass and concrete composites. Our analysis revealed that the copper oxide-reinforced borosilicate glass container demonstrated a significant transmission factor (TF) value decrease by approximately 15% compared to steel–magnetite concrete at 1.3325 MeV, with a standard deviation of ±1.5%, indicating its lower protective characteristics. Nonetheless, it exhibited a 10% higher TF reduction compared to the cement–bitumen mix at the same energy level, with a precision error of ±1.2%. In addition, the half-value layer for this glass was determined to be 2.5 cm for 1.3325 MeV gamma rays, showing moderate shielding capacity. The study demonstrates that optimizing the oxide content in the borosilicate glass matrix significantly enhances its shielding effectiveness. This advancement in nuclear waste management materials is justified by our comprehensive evaluation, highlighting the potential of optimized glass materials to outperform traditional concrete in certain scenarios, thus contributing to the development of more effective nuclear waste containment solutions.

In this experiment, a general purpose BP neural network (BP) based on genetic algorithm (GA) was developed for predicting fiber properties. The experiment is based on the breaking force of cotton fibers, and the controlled variable method is used for sampling test to collect 878 datasets containing four eigenvalues. The first 850 items of this dataset were then utilized to train the designed BP, and the remaining 28 items were evaluated for error. Next, the model is parameterized using a genetic algorithm to reduce the overall network size, thus optimizing the fit. Finally, the improved model was evaluated using the same dataset. The results were obtained: the MAPE was reduced from 10.94% to 3.7869%, the MAE was reduced from 0.39586 to 0.14584, and the MSE was reduced from 0.32161 to 0.05201. The results show that this GA-BP has better results for nonlinear fitting, and it can make a better correspondence to the outliers in the dataset, and also produces a smaller error in the fitting results, the Overall, the method is effective.

The purpose of this study is to determine the material properties of CFRP composites in the form of a fabric for the construction of racing car bodywork. This work focused on the determination of the strength and tribological properties as well as investigating the effects of the operating environment on the developed material. Three material variants, differing in the number of layers used to produce the reinforcement, were used in this study. The tests were carried out on two-/three-/four-layer sheets produced by infusion. Due to the later use of the tested composites for the sheathing of a racing car, the results obtained were analysed in terms of the most favourable strength properties while keeping the weight as low as possible. In this study, the hardness, impact strength, and tensile and bending stresses of the developed composites were examined. In addition to the strength properties, the density, the effects of immersion in water, and the composite's resistance to staining and friction in the presence of aggressive media were also checked. The structure and the breakthroughs resulting from the strength tests were observed using a stereoscopic microscope. The material's resistance to sunlight and UVB was also tested. [ABSTRACT FROM AUTHOR]

For the 3D STAR project and 3D printing purposes, a special fine-grained cement mixture from locally available raw materials was developed. The reason for the development of the custom mixture was the possibility of arbitrary optimization of the developed mixture at any stage of the project and for any type of application. Mix design, printing head and the entire system from mixing to extrusion was the subject of research and development for this project. It was therefore necessary to address both issues in parallel and to respond in both sectors to the realities arising from the partial results of the different groups involved in the development. [ABSTRACT FROM AUTHOR]