Editor’s Choice Articles

Acetaldehyde decomposition was performed under heating at a temperature range of 25–125 °C and UV irradiation on TiO₂ doped by metallic Ni powder and TiO₂ supported on nickel foam. The process was carried out in a high-temperature reaction chamber, “The Praying Mantis^TM”, with simultaneous in situ FTIR measurements and UV irradiation. Ni powder was added to TiO₂ in the quantity of 0.5 to 5.0 wt%. The photothermal measurements of acetaldehyde decomposition indicated that the highest yield of acetaldehyde conversion on TiO₂ and UV irradiation was obtained at 75 °C. The doping of nickel to TiO₂ did not increase its photocatalytic activity. Contrary to that, the application of nickel foam as a support for TiO₂ appeared to be highly advantageous because it increased the decomposition of acetaldehyde from 31 to 52% at 25 °C, and then to 85% at 100 °C in comparison with TiO₂ itself. At the same time, the mineralization of acetaldehyde to CO₂ doubled in the presence of nickel foam. However, oxidized nickel foam used as support for TiO₂ was detrimental. Most likely, different mechanisms of electron transfer between Ni–TiO₂ and NiO-TiO₂ occurred. The application of nickel foam greatly enhanced the separation of free carriers in TiO₂. As a consequence, high yields from the photocatalytic reactions were obtained. Full article

Magnesium (Mg) alloy is a widely used lightweight metal structural material due to its high specific strength and stiffness, excellent damping performance, and recyclability. Wrought Mg alloys are particularly favored in fields such as aerospace, transportation, and biomedical stents. However, most wrought Mg alloys with a hexagonal close-packed (HCP) crystal structure lack sufficient independent slip systems to meet the von Mises criterion for uniform plastic deformation at room temperature. This can result in the formation of a strong basal texture during plastic deformation and poor room temperature plastic formability. Enhancing the room temperature forming performance is therefore a crucial challenge that needs to be addressed in order to expand the application of Mg alloy sheets. Our research group has comprehensively summarized significant work and the latest research progress in improving the room temperature forming of Mg alloy sheets via extrusion technology in recent years. Specifically, we have developed a new type of asymmetric extrusion technology that combines material structure evolution, mechanical properties, and forming behavior analysis. We have elucidated the extrusion process characteristics, texture control mechanism, and forming properties of Mg alloy sheets through plastic deformation mechanisms, mold design, and finite element numerical simulation. The findings of our study present an innovative extrusion technology for the fabrication of highly formable Mg alloy sheets, which can be utilized in various applications. Full article

To suppress the corrosion and erosion wear of dissolvable magnesium alloy ball seats in wellbores, Fe-based amorphous coatings were deposited on dissolvable Mg-RE alloy substrates, and their microstructure, corrosion behavior, and erosion wear behavior were studied. The thickness of Fe-based amorphous coatings on dissolvable Mg-RE alloy substrates can reach 1000 μm without any cracks, and their porosity and amorphous contents are 0.79% and 86.8%, respectively. Although chloride ions will damage the compactness and protective efficacy of passive films, Fe-based amorphous coatings still maintain low corrosion current density (3.31 μA/cm²) and high pitting potential (1 V_SCE) in 20 wt% KCl solution. Due to their higher hardness, the erosion wear resistance of Fe-based amorphous coatings is about 4.16 times higher than that of dissolvable Mg-RE alloy substrates when the impact angle is 30°. Moreover, the erosion rates of Fe-based amorphous coatings exhibit a nonlinear relationship with the impact angle, and the erosion rate reaches the highest value when the impact angle is 60°. The erosion wear mechanisms of Fe-based AMCs vary with the impact angles, including cutting, delamination, splat fracture, and deformation wear. This work can provide effective guidance for the corrosion and wear protection of plugging tools made from dissolvable magnesium alloy. Full article

The extracellular matrix (ECM) of natural cells typically exhibits dynamic mechanical properties (viscoelasticity and dynamic stiffness). The viscoelasticity and dynamic stiffness of the ECM play a crucial role in biological processes, such as tissue growth, development, physiology, and disease. Hydrogels with viscoelasticity and dynamic stiffness have recently been used to investigate the regulation of cell behavior and fate. This article first emphasizes the importance of tissue viscoelasticity and dynamic stiffness and provides an overview of characterization techniques at both macro- and microscale. Then, the viscoelastic hydrogels (crosslinked via ion bonding, hydrogen bonding, hydrophobic interactions, and supramolecular interactions) and dynamic stiffness hydrogels (softening, stiffening, and reversible stiffness) with different crosslinking strategies are summarized, along with the significant impact of viscoelasticity and dynamic stiffness on cell spreading, proliferation, migration, and differentiation in two-dimensional (2D) and three-dimensional (3D) cell cultures. Finally, the emerging trends in the development of dynamic mechanical hydrogels are discussed. Full article

Polylactide (PLA) is one of the most commonly used biomaterials nowadays, with many recognized benefits, particularly in the packaging and single-use products industries. However, little research has been conducted on its stretching behavior. This work investigates the optimal conditions of biaxial stretching of injection-molded PLA samples produced under different processing conditions (pressure, drying, and pre-processing by extrusion, to simulate a recycling step). The injection-molded samples were characterized to determine their mechanical, thermal and thermo-mechanical behavior, water absorption, thermal behavior, and crystallization kinetics. The extruded samples showed reduced thermal stability, lower viscosity, decreased mechanical properties, and higher crystallization rates due to thermal degradation. However, the stretched samples provided similar properties regardless of the materials pre-processing. Regarding the assessment of the biaxial stretching process, processing at lower temperatures provides the films with a higher yield and breaking strength, while the time and strain rates have little influence on such properties. It was then determined that 82 °C is the optimal temperature for stretching the PLA samples. An increase in the stretch ratio provided a higher elastic modulus and higher values of opacity due to an increased crystallinity induced by stress during the process. Films as thin as 50 μm can be obtained by biaxially stretching injection-molded preforms, producing a deformation over 150% and acquiring good mechanical properties: about 90 MPa for the yield and a breaking strength and elastic modulus of 4000 MPa. Full article

In the present work, the acid-catalyzed interesterification of glyceryl trioctanoate (GTO) with ethyl acetate was investigated as a model reaction for the one-step production of biofuel and its additives. The activity of heterogeneous acid catalysts, such as silica-based propyl-sulfonic ones, was evaluated. Propyl-sulfonic groups were grafted on both amorphous and mesoporous silica oxide (SBA-15, KIT-6) using different functionalization processes and characterized by N₂ adsorpion–desorption isotherm (BET), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy, and potentiometric titration. During the optimization of the reaction conditions with the most active catalyst (Am-Pr-SO₃H), it was shown that the addition of ethanol allowed a total conversion of GTO together with 89% and 56% yield of ethyl octanoate and triacetin, respectively. The catalytic performance is strictly correlated to the catalyst features, in terms of both the acid capacity and the porous structure. Moreover, the catalytic performance is also affected by a synergistic mechanism between silanols and Pr-SO₃H groups towards the ‘silanolysis’ of ethyl acetate. The overall results show that the presence of ethanol, the reaction time, and the amount of catalyst shifts the reaction towards the formation of the biofuel mixture composed by ethyl octanoate and triacetin. Full article

Shot peening is a process wherein the surface of a material is impacted by small, spherical metal shots at high velocity to create residual stresses. Nickel-based superalloy is a material with high strength and hardness along with excellent corrosion and fatigue resistance, and it is therefore used in nuclear power plants and aerospace applications. The application of shot peening to INCONEL, a nickel-based superalloy, has been actively researched, and the measurement of residual stresses has been studied as well. Previous studies have used methods such as perforation strain gauge analysis and X-ray diffraction (XRD) to measure residual stress, which can be evaluated with high accuracy, but doing so damages the specimen and involves critical risks to operator safety due to radiation. On the other hand, ultrasonic testing (UT), which utilizes ultrasonic wave, has the advantage of relatively low unit cost and short test time. One UT method, minimum reflection measurement, uses Rayleigh waves to evaluate the properties of material surfaces. Therefore, the present study utilized ultrasonic minimum reflectivity measurements to evaluate the residual stresses in INCONEL specimens. Specifically, this study utilized ultrasonic minimum reflection measurements to evaluate the residual stress in INCONEL 718 specimens. Moreover, an estimation equation was assumed using exponential functions to estimate the residual stress with depth using the obtained data, and an optimization problem was solved to determine it. Finally, to evaluate the estimated residual stress graph, the residual stress of the specimen was measured and compared using the XRD method. Full article

NiTiO₃-BiOBr heterostructured photocatalysts were constructed via precipitation, calcination and hydrothermal treatments. Various characterizations demonstrated that BiOBr nanosheets were decorated on NiTiO₃ nanoparticals, forming porous rod-like heterojunctions. Compared with independent NiTiO₃ and BiOBr, the composites with optimal BiOBr content presented highly improved visible-light photocatalytic efficiency. The degradation rates of Rhodamine B (RhB) and tetracycline (TC) reached 96.6% in 1.5 h (100% in 2 h) and 73.5% in 3 h, which are 6.61 and 1.53 times those of NiTiO₃, respectively. The result is an improved photocatalytic behavior from the formation of heterojunctions with a large interface area, which significantly promoted the separation of photogenerated carriers and strengthened the visible-light absorption. Based on the free radical capture experiments and band position analysis, the photodegradation mechanism of type-II heterojunction was deduced. This study provides a new way to fabricate highly efficient NiTiO₃-based photocatalysts for degrading certain organics. Full article

I-III-VI type QDs have unique optoelectronic properties such as low toxicity, tunable bandgaps, large Stokes shifts and a long photoluminescence lifetime, and their emission range can be continuously tuned in the visible to near-infrared light region by changing their chemical composition. Moreover, they can avoid the use of heavy metal elements such as Cd, Hg and Pb and highly toxic anions, i.e., Se, Te, P and As. These advantages make them promising candidates to replace traditional binary QDs in applications such as light-emitting diodes, solar cells, photodetectors, bioimaging fields, etc. Compared with binary QDs, multiple QDs contain many different types of metal ions. Therefore, the problem of different reaction rates between the metal ions arises, causing more defects inside the crystal and poor fluorescence properties of QDs, which can be effectively improved by doping metal ions (Zn²⁺, Mn²⁺ and Cu⁺) or surface coating. In this review, the luminous mechanism of I-III-VI type QDs based on their structure and composition is introduced. Meanwhile, we focus on the various synthesis methods and improvement strategies like metal ion doping and surface coating from recent years. The primary applications in the field of optoelectronics are also summarized. Finally, a perspective on the challenges and future perspectives of I-III-VI type QDs is proposed as well. Full article

This paper introduces a novel method for estimating the cyclic stress–strain curves of steels based on their monotonic properties and plastic strain amplitudes, utilizing artificial neural networks (ANNs). ANNs were trained on a substantial number of experimental data for steels, collected from relevant literature, and divided into subgroups according to alloying elements content (unalloyed, low-alloy, and high-alloy steels). Only monotonic properties that were proven to be relevant for the estimation of points on the stress–strain curve were used. The performance of the developed ANNs was assessed using an independent set of data, and the results were compared to experimental values, values obtained by existing empirical estimation methods, and by previously developed ANNs. The results showed that the new approach which combines relevant monotonic properties and plastic strain amplitudes as inputs to ANNs for cyclic stress–strain curve estimation is better than the previously used approach where ANNs estimate the parameters of the Ramberg–Osgood material model separately. This shows that a more favorable approach to the estimation of cyclic stress–strain behavior would be to directly estimate corresponding material curves using monotonic properties. Additionally, this may also reduce inaccuracies resulting from simplified representations of the actual material behavior inherent in the material model. Full article

Hybrid materials based on graphitic carbon nitride (g-C₃N₄) and NTU-9 metal–organic frameworks (MOF) were designed and prepared via solvothermal synthesis and calcination in air. The as-prepared photocatalysts were subsequently characterized using Brunauer–Emmett–Teller (BET) analysis, UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The obtained NTU-9/C₃N₄ composites showed a greatly improved photocatalytic performance for the degradation of toluene in the gas phase under LED visible-light irradiation (λ_max = 415 nm). The physicochemical properties and photocatalytic activities of the obtained NTU-9/C₃N₄ materials were tuned by varying the NTU-9 content (5–15 wt%) and preparation method of the composite materials. For composites prepared by calcination, the photocatalytic activity increased with decreasing NTU-9 content as a result of the formation of TiO₂ from the MOFs. The best photocatalytic performance (65% of toluene was photodegraded after 60 min) was achieved by the NTU-9/C₃N₄ sample prepared via the solvothermal method and containing 15 wt% MOF, which can be attributed to the appropriate amount and stable combination of composite components, efficient charge separation, and enhanced visible-light absorption ability. The photocatalytic mechanisms of the prepared hybrid materials depending on the preparation method are also discussed. Full article

Ceramic waste forms are designed to immobilize radionuclides for permanent disposal in geological repositories. One of the principal criteria for the effective incorporation of waste elements is their compatibility with the host material. In terms of performance under environmental conditions, the resistance of the waste forms to degradation over long periods of time is a critical concern when they are exposed to natural environments. Due to their unique crystallographic features and behavior in nature environment as exemplified by their natural analogues, ceramic waste forms are capable of incorporating problematic nuclear waste elements while showing promising chemical durability in aqueous environments. Recent studies of apatite- and hollandite-structured waste forms demonstrated an approach that can predict the compositions of ceramic waste forms and their long-term dissolution rate by a combination of computational techniques including machine learning, first-principles thermodynamics calculations, and modeling using kinetic rate equations based on critical laboratory experiments. By integrating the predictions of elemental incorporation and degradation kinetics in a holistic framework, the approach could be promising for the design of advanced ceramic waste forms with optimized incorporation capacity and environmental degradation performance. Such an approach could provide a path for accelerated ceramic waste form development and performance prediction for problematic nuclear waste elements. Full article

The present article investigates the possibility of simulating the electrical conductivity of carbon nanotube-reinforced polymer composites by numerical methods. Periodic representative volume elements are generated by randomly distributing perfectly conductive reinforcements in an insulating matrix and are used to assemble an electrical network representative of the nanocomposite, where the nanotube–nanotube contacts are considered equivalent resistors modeled by means of Simmons’ equation. A comparison of the results with experimental data from the literature supports the conclusion that a random distribution of reinforcements is not suitable for simulating this class of materials since percolation thresholds and conductivity trends are different, with experimental percolation taking place before the expectations. Including nanotube curvature does not solve the issue, since it hinders percolation even further. In agreement with experimental observations, the investigation suggests that a suitable approach requires the inclusion of aggregation during the volume element generation to reduce the volume fraction required to reach percolation. Some solutions available in the literature to generate properly representative volume elements are thus listed. Concerning strain sensing, the results suggest that representative volume elements generated with random distributions overestimate the strain sensitivity of the actual composites. Full article

Equation-Informed Neural Networks (EINNs) are developed as an efficient method for extracting the coefficients of constitutive equations. Subsequently, numerical Bayesian Inference (BI) iterations were applied to estimate the distribution of these coefficients, thereby further refining them. We could generate coefficients optimally aligned with the targeted application scenario by carefully adjusting pre-processing mapping parameters and identifying dataset preferences. Leveraging graphical representation techniques, the EINNs formulation is implemented in temperature- and strain-rate-dependent hyperbolic Garofalo, Anand, and Chaboche constitutive models to extract the corresponding coefficients for lead-free SAC305 solder material. The performance of the EINNs-based extracted coefficients, obtained from experimental results of SAC305 solder material, is comparable to existing studies. The methodology offers the dual advantage of providing the coefficients’ value and distribution against the training dataset. Full article

Negative capacitance (NC), already observed in conducting polymer-based nanocomposites, was recently reported and evidenced at low frequencies (<10 kHz) in non-conducting polymer-based nanocomposites containing conductive particles. In this contribution, we demonstrate that it is possible to produce economic high-density polyethylene (HDPE) nanocomposites exhibiting an NC effect at low frequencies via a convenient and environmentally friendly extrusion-like process by only adjusting the duration of melt-mixing. Nanocomposite materials are produced by confining a limited quantity, i.e., 4.6 wt.%, of multiwalled carbon nanotubes (CNTs) within semi-crystalline HDPE to reach the percolation threshold. With increasing melt processing time, crystallites of HDPE developing at the surface of CNTs become bigger and perturbate the connections between CNTs leading to a dramatic change in the electrical behavior of the systems. More specifically, the link between NC and current oscillations is stressed while the dependence of NC with the size of polymer crystallites is evidenced. NC tends to appear when space charge effects take place in HDPE/MWCNT interfaces, in structures with convenient crystallite sizes corresponding to 10 min of melt-mixing. Full article

In situ fenestration of endovascular stent-grafts has become a mainstream bailout technique to treat complex emergent aneurysms while maintaining native anatomical visceral and aortic arch blood supplies. Fabric tearing from creating the in situ fenestration using balloon angioplasty may extend beyond the intended diameter over time. Further tearing may result from the physiologic pulsatile motion at the branching site. A resultant endoleak at the fenestrated sites in stent-grafts could ultimately lead to re-pressurization of the aortic sac and, eventually, rupture. In an attempt to address this challenge, plain woven fabrics were designed. They hold a specific corona surrounding a square-shaped cluster with a plain weave fabric structure, a 2/2 twill, or a honeycomb. The corona was designed to stop potential further tearing of the fabric caused by the initial balloon angioplasty and stent or later post-implantation motion. The cluster within the corona was designed with relatively loose fabric structures (plain weave, 2/2 twill weave, and honeycomb) to facilitate the laser fenestration. Two commercial devices, Anaconda (Vascutek, Terumo Aortic) and Zenith TX2 (Cook), were selected as controls for comparison against this new design. All the specimens were characterized by morphology, thickness, and water permeability. The results demonstrated that all specimens with a low thickness and water permeability satisfied the requirements for a stent graft material that would be low profile and resistant to endoleaks. The in situ fenestrations were performed on all fabrics utilizing an Excimer laser followed by balloon angioplasty. The fabrics were further observed by light microscopy and scanning electron microscopy. The dimension of the fenestrated apertures was smaller than the balloon’s diameter. The tearing was effectively confined within the corona. The clinical acceptability of this concept deserves additional bench testing and animal experimentation. Full article

Fibre-reinforced polymer composites in general, and especially glass fibre-reinforced polymer (GFRP), have increasingly been used in recent decades in construction. The advantages of GFRP as an alternative construction material are its high strength-to-weight ratio, corrosive resistance, high durability, and ease of installation. The main purpose of this study is to evaluate the response of GFRP under dynamic conditions (more specifically, under seismic loads) and to compare the performance of this composite material with that of two traditional building materials: reinforced concrete and structural steel. To this aim, a finite element analysis is carried out on a two-dimensional frame modelled with steel, reinforced concrete (RC), or GFRP pultruded materials and subjected to a seismic input. The dynamic response of the structure is evaluated for the three building materials in terms of displacements, inter-storey drift, base shear, and stress. The results show a good performance of the GFRP frame, with stress distribution and displacements halfway between those of RC and steel. Most importantly, the GFRP frame outperforms the other materials in terms of reduced weight and, thus, base shear (−40% compared to steel and −88.5% compared to RC). Full article

Dielectric materials are highly desired for pulsed power capacitors due to their ultra-fast charge-discharge rate and excellent fatigue behavior. Nevertheless, the low energy storage density caused by the low breakdown strength has been the main challenge for practical applications. Herein, we report the electric energy storage properties of (1 − x) Bi_0.5(Na_0.8K_0.2)_0.5TiO₃-xBi_0.2Sr_0.7TiO₃ (BNKT-BST; x = 0.15–0.50) relaxor ferroelectric ceramics that are enhanced via a domain engineering method. A rhombohedral-tetragonal phase, the formation of highly dynamic PNRs, and a dense microstructure are confirmed from XRD, Raman vibrational spectra, and microscopic investigations. The relative dielectric permittivity (2664 at 1 kHz) and loss factor (0.058) were gradually improved with BST (x = 0.45). The incorporation of BST into BNKT can disturb the long-range ferroelectric order, lowering the dielectric maximum temperature T_m and inducing the formation of highly dynamic polar nano-regions. In addition, the T_m shifts toward a high temperature with frequency and a diffuse phase transition, indicating relaxor ferroelectric characteristics of BNKT-BST ceramics, which is confirmed by the modified Curie-Weiss law. The rhombohedral-tetragonal phase, fine grain size, and lowered T_m with relaxor properties synergistically contribute to a high P_max and low P_r, improving the breakdown strength with BST and resulting in a high recoverable energy density W_rec of 0.81 J/cm³ and a high energy efficiency η of 86.95% at 90 kV/cm for x = 0.45. Full article

The 11 system in the iron-based superconducting family has become one of the most extensively studied materials in the research of high-temperature superconductivity, due to their simple structure and rich physical properties. Many exotic properties, such as multiband electronic structure, electronic nematicity, topology and antiferromagnetic order, provide strong support for the theory of high-temperature superconductivity, and have been at the forefront of condensed matter physics in the past decade. One noteworthy aspect is that a high upper critical magnetic field, large critical current density and lower toxicity give the 11 system good application prospects. However, the research on 11 iron-based superconductors faces numerous obstacles, mainly stemming from the challenges associated with producing high-quality single crystals. Since the discovery of FeSe superconductivity in 2008, researchers have made significant progress in crystal growth, overcoming the hurdles that initially impeded their studies. Consequently, they have successfully established the complete phase diagrams of 11 iron-based superconductors, including FeSe_1−xTe_x, FeSe_1−xS_x and FeTe_1−xS_x. In this paper, we aim to provide a comprehensive summary of the preparation methods employed for 11 iron-based single crystals over the past decade. Specifically, we will focus on hydrothermal, chemical vapor transport (CVT), self-flux and annealing methods. Additionally, we will discuss the quality, size, and superconductivity properties exhibited by single crystals obtained through different preparation methods. By exploring these aspects, we can gain a better understanding of the advantages and limitations associated with each technique. High-quality single crystals serve as invaluable tools for advancing both the theoretical understanding and practical utilization of high-temperature superconductivity. Full article

The structure of metallic materials has a significant impact on their properties. One of the most popular methods to form the properties of metal alloys is heat treatment, which uses thermally activated transformations that take place in metals to achieve the required mechanical or physicochemical properties. The phase transformation in steel results from the fact that one state becomes less durable than the other due to a change in conditions, for example, temperature. Phase transformations are an extensive field of research that is developing very dynamically both in the sphere of experimental and model research. The objective of this paper is the development of a 3D heat flow model to model heat transfer during diffusional phase transformations in carbon steels. This model considers the two main factors that influence the transformation: the temperature and the enthalpy of transformation. The proposed model is based on the lattice Boltzmann method (LBM) and uses CUDA parallel computations. The developed heat flow model is directly related to the microstructure evolution model, which is based on frontal cellular automata (FCA). This paper briefly presents information on the FCA, LBM, CUDA, and diffusional phase transformation in carbon steels. The structures of the 3D model of heat flow and their connection with the microstructure evolution model as well as the algorithm for simulation of heat transfer with consideration of the enthalpy of transformation are shown. Examples of simulation results of the growth of the new phase that are determined by the overheating/overcooling and different model parameters in the selected planes of the 3D calculation domain are also presented. Full article

This paper presents the first results on the characterisation of the damage behaviour of recycled carbon fibre (rCF) rovings manufactured into unidirectionally (UD) reinforced plates. In the first step, the mechanical properties of several material combinations were determined by mechanical tests (tensile, flexural, compression). This proves the usability of the material for load-bearing structures. For example, a tensile modulus of up to 80 GPa and a tensile strength of 800 MPa were measured. Subsequently, the fracture surface was analysed by scanning electron microscopy (SEM) to characterise the fibre–matrix adhesion and to obtain first indications of possible failure mechanisms. Despite the high mechanical properties, poor fibre–matrix adhesion was found for all matrix systems. In situ X-ray microscopy tests were then performed on smaller specimens under predefined load levels as transverse tensile and bending tests. The results provide further predictions of the failure behaviour and can be compared to the previous test results. The three-dimensional scan reconstruction results were used to visualise the failure behaviour of the staple fibres in order to detect fibre pull-out and fibre or inter-fibre failure and to draw initial conclusions about the damage behaviour in comparison to conventional fibre composites. In particular, a benign failure behaviour in the transverse tensile test was demonstrated with this procedure. In addition, first concepts and tests for the integration of AE analysis into the in situ setup of the X-ray microscope are presented. Full article

The effects of various organic additives, such as diethanolamine (DEA) and ethanolamine (EA), and variations in aging times on the formation and stability mechanisms of spherical aggregates of ZnO nanoparticles (NPs) prepared by using solvothermal synthesis were studied. The experimental results of the structural, morphological and optical properties monitored by using X-ray diffraction, field-emission scanning electron microscopy (FE-SEM) and UV-Vis spectroscopy were supported by quantum chemical calculations at the level of density functional theory (DFT). Understanding the mechanism of spherical ZnO aggregate formation and its stability by mimicking the processes at the computer level was achieved through theoretical simulations of the ZnO surface/additive interactions using (ZnO)₃₆–DEA and (ZnO)₃₆–EA models. The fine-tuned spherical aggregation of ZnO nanoparticles was driven by various interactions, in particular, strong O–H∙∙∙O and weak N–H∙∙∙O hydrogen bonds as controlling interactions. The calculated negative free release energy, ∆G*_INT, indicates that the ZnO surface/additive interaction in diethanolamine media is a spontaneous exergonic process (∆G*_INT = −7.73 kcal mol⁻¹), whereas, in ethanolamine media, it is an unfavorable, slightly endergonic process (∆G*_INT > 0). The presence of two strong O–H∙∙∙O hydrogen bonds and, at the same time, a weaker N–H∙∙∙O hydrogen bond is the key factor for the very good and long-term aggregate stability of ZnO NPs in DEA media. This integrated experimental–theoretical study highlights the stability and compactness of spherical ZnO aggregates of ZnO NPs, prepared in the presence of diethanolamine compared to ethanolamine media, and provides a promising method and flexible design of ZnO nanomaterials to improve their adsorptive and optical properties. Full article

Laser treatment has often been applied to rebuild the surface layer of titanium and its alloys destined for long-term implants. Such treatment has always been associated with forming melted and re-solidified thin surface layers. The process parameters of such laser treatment can be different, including the patterning of a surface by so-called direct writing. In this research, pulse laser treatment was performed on the Ti13Nb13Zr alloy surface, with the distance between adjacent laser paths ranging between 20 and 50 µm. The obtained periodic structures were tested to examine the effects of the scan distance on the microstructure using SEM, the roughness and chemical and phase composition using EDS and XRD, and the mechanical properties using the nanoindentation technique. After direct laser writing, the thickness of the melted layers was between 547 and 123 µm, and the surface roughness varied between 1.74 and 0.69 µm. An increase in hardness was observed after laser treatment. The highest hardness, 5.44 GPa, was obtained for the sample modified with a laser beam spacing of 50 µm. The value of the distance has been shown to be important for several properties and related to a complex microstructure of the thin surface layer close to and far from the laser path. Full article

High-performance Nd-Fe-B-based rare-earth permanent magnets play a crucial role in the application of traction motors equipped in new energy automobiles. In particular, the anisotropic hot-deformed (HD) Nd-Fe-B magnets prepared by the hot-press and hot-deformation process show great potential in achieving high coercivity due to their fine grain sizes of 200–400 nm, which are smaller by more than an order of magnitude compared to the traditional sintered Nd-Fe-B magnets. However, the current available coercivity of HD magnets is not as high as expected according to an empirical correlation between coercivity and grain size, only occupying about 25% of its full potential of the anisotropy field of the Nd₂Fe₁₄B phase. For the sake of achieving high-coercivity HD magnets, two major routes have been developed, namely the grain boundary diffusion process (GBDP) and the dual alloy diffusion process (DADP). In this review, the fundamentals and development of the HD Nd-Fe-B magnets are comprehensively summarized and discussed based on worldwide scientific research. The advances in the GBDP and DADP are investigated and summarized based on the latest progress and results. Additionally, the mechanisms of coercivity enhancement are discussed based on the numerous results of micromagnetic simulations to understand the structure–property relationships of the HD Nd-Fe-B magnets. Lastly, the magnetization reversal behaviors, based on the observation of magneto-optic Kerr effect microscopy, are analyzed to pinpoint the weak regions in the microstructure of the HD Nd-Fe-B magnets. Full article

The superheating process is a unique grain refining method found only in aluminum-containing magnesium alloys. It is a relatively simple method of controlling the temperature of the melt without adding a nucleating agent or refining agent for grain refinement. Although previous studies have been conducted on this process, the precise mechanism underlying this phenomenon has yet to be elucidated. In this study, a new approach was used to investigate the grain refinement mechanism of aluminum-containing magnesium alloys by the melting superheating process. AZ91 alloy, a representative Mg-Al alloy, was used in the study, and a rapid solidification process was designed to enable precise temperature control. Temperature control was successfully conducted in a unique way by measuring the temperature of the ceramic tube during the rapid solidification process. The presence of Al₈Mn₅ and Al₁₀Mn₃ particles in non-superheated and superheated AZ91 ribbon samples, respectively, manufactured by the rapid solidification process, was revealed. The role of these Al-Mn particles as nucleants in non-superheated and superheated samples was examined by employing STEM equipment. The crystallographic coherence between Al₈Mn₅ particles and magnesium was very poor, while Al₁₀Mn₃ particles showed better coherence than Al₈Mn₅. We speculated that Al₁₀Mn₃ particles generated by the superheating process may act as nucleants for α-Mg grains; this was the main cause of the superheating grain refinement of the AZ91 alloy. Full article

The main objective of this work was to study the effects of carbon nanotubes (CNTs) on the strength and electrical properties of cement mortar. Molecular dynamic simulations (MDSs) were carried out to determine the mechanical and electrical properties of a cementitious composite and its associated mechanisms. To model the atomic structure of a calcium silicate hydrate (C-S-H) gel, tobermorite 11Å was chosen. Single-walled carbon nanotubes (SWCNTs) embedded in a tobermorite structure were tested numerically. In particular, it was concluded that a piezoelectric effect can be effectively simulated by varying the concentration levels of carbon nanotubes. The deformation characteristics were analyzed by subjecting a sample to an electrical field of 250 MV/m in the z-direction in a simulation box. The results indicated a progressively stronger converse piezoelectric response with an increasing proportion of carbon nanotubes. Additionally, it was observed that the piezoelectric constant in the z-direction, denoted by d33, also increased correspondingly, thereby validating the potential for generating an electrical current during sample deformation. An innovative experiment was developed for the electrical characterization of a cementitious composite of carbon nanotubes. The results showed that the electrostatic current measurements exhibited a higher electric sensitivity for samples with a higher concentration of CNTs. Full article

X-ray $\mathsf{\mu }$CT imaging is a common technique that is used to gain access to the full-field characterization of materials. Nevertheless, the process can be expensive and time-consuming, thus limiting image availability. A number of existing generative models can assist in mitigating this limitation, but they often lack a sound physical basis. This work presents a physics-supervised generative adversarial networks (GANs) model and applies it to the generation of X-ray $\mathsf{\mu }$CT images. FEM simulations provide physical information in the form of elastic coefficients. Negative X-ray $\mathsf{\mu }$CT images of a Hostun sand were used as the target material. During training, image batches were evaluated with nonparametric statistics to provide posterior metrics. A variety of loss functions and FEM evaluation frequencies were tested in a parametric study. The results show, that in several test scenarios, FEM-GANs-generated images proved to be better than the reference images for most of the elasticity coefficients. Although the model failed at perfectly reproducing the three out-of-axis coefficients in most cases, the model showed a net improvement with respect to the GANs reference. The generated images can be used in data augmentation, the calibration of image analysis tools, filling incomplete X-ray $\mathsf{\mu }$CT images, and generating microscale variability in multiscale applications. Full article

It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) has outstanding advantages in reducing the density and increasing the elastic modulus in aluminum alloys, so Al-Zn-Mg-Cu alloys containing Li have gained widespread attention. Furthermore, since the Al-Zn-Mg-Cu alloy is usually strengthened by aging treatment, it is crucial to understand how Li addition affects its aging precipitation process. As such, in this article, the effects and mechanism of Li on the aging precipitation behavior and the impact of Li content on the aging precipitation phase of Al-Zn-Mg-Cu alloys are briefly reviewed, and the influence of Li on the service properties, including mechanical properties, wear resistance, and fatigue resistance, of Al-Zn-Mg-Cu alloys are explained. In addition, the corresponding development prospects and challenges of the Al-Zn-Mg-Cu-Li alloy are also proposed. This review is helpful to further understand the role of Li in Al-Zn-Mg-Cu alloys and provides a reference for the development of high-strength aluminum alloys containing Li with good comprehensive properties. Full article

An ammonia sensor based on a delay-line surface acoustic wave (SAW) device is developed in this study by coating the delay line area of the device with a nano-structured molybdenum disulfide (MoS₂) sensitive material. A SAW device of 122 MHz was designed and fabricated with a pair of interdigital transducers (IDTs) defined on a 128° y-cut LiNbO₃ substrate using photolithography technologies, and the aluminum IDT electrodes were deposited by a DC magnetron sputtering system. By adjusting the pH values of precursor solutions, molybdenum disulfide (MoS₂) nanospheres were prepared with various structures using a hydrothermal method. Finally, an NH₃ gas sensor with high sensitivity of 4878 Hz/ppm, operating at room temperature, was successfully obtained. The excellent sensitivity performance may be due to the efficient adsorption of NH₃ gas molecules on the surfaces of the nanoflower-like MoS₂, which has a larger specific surface area and provides more active sites, and results in a larger change in the resonant frequency of the device due to the mass loading effect. Full article

Agricultural waste, which is produced in large quantities annually, can be a threat to the environment. Biochar (BC) production represents a potential solution for reducing the amount of grapevine pruning residues and, accordingly, the impact on the environment and climate change. Biochar produced by the process of pyrolysis from grapevine pruning residues was investigated and characterized to be applied as an adsorbent of polyphenolic compounds with the aim of using the waste from viticultural production to obtain a quality product with adsorption and recovery potential. Standards of caffeic acid (CA), gallic acid (GA), and oleuropein (OLP) were used as polyphenolic representatives. The obtained data were fitted with the Langmuir and Freundlich isotherms models to describe the adsorption process. The best K_L (0.39) and R² (0.9934) were found for OLP using the Langmuir model. Furthermore, the adsorption dynamics and recovery potential of BC were investigated using an adapted BC column and performed on an HPLC instrument. The adsorption dynamics of biochar resulted in the adsorption of 5.73 mg CA g⁻¹ of BC, 3.90 mg GA g⁻¹ of BC, and 3.17 mg OLP g⁻¹ of BC in a 24 h contact. The online solid phase extraction of the compounds performed on an HPLC instrument yielded a recovery of 41.5 ± 1.71% for CA, 61.8 ± 1.16% for GA, and 91.4 ± 2.10% for OLP. The investigated biochar has shown a higher affinity for low-polar compound adsorption and, consequently, a higher polar compound recovery suggesting its potential as an efficient polyphenolic compound adsorbent. Full article

This research study thoroughly examines the optimal thickness of indium tin oxide (ITO), a transparent electrode, for near-ultraviolet (NUV) light-emitting diodes (LEDs) based on InGaN/AlGaInN materials. A range of ITO thicknesses from 30 to 170 nm is investigated, and annealing processes are performed to determine the most favorable figure of merit (FOM) by balancing transmittance and sheet resistance in the NUV region. Among the films of different thicknesses, an ITO film measuring 110 nm, annealed at 550 °C for 1 min, demonstrates the highest FOM. This film exhibits notable characteristics, including 89.0% transmittance at 385 nm, a sheet resistance of 131 Ω/□, and a contact resistance of 3.1 × 10⁻³ Ω·cm². Comparing the performance of NUV LEDs using ITO films of various thicknesses (30, 50, 70, 90, 130, 150, and 170 nm), it is observed that the NUV LED employing ITO with a thickness of 110 nm achieves a maximum 48% increase in light output power at 50 mA while maintaining the same forward voltage at 20 mA. Full article

Delayed atomic layer deposition (ALD) of ZnO, i.e., area selective (AS)-ALD, was successfully achieved on silicon wafers (Si\SiO₂) terminated with tris(dimethylamino)methylsilane (TDMAMS). This resist molecule was deposited in a home-built, near-atmospheric pressure, flow-through, gas-phase reactor. TDMAMS had previously been shown to react with Si\SiO₂ in a single cycle/reaction and to drastically reduce the number of silanols that remain at the surface. ZnO was deposited in a commercial ALD system using dimethylzinc (DMZ) as the zinc precursor and H₂O as the coreactant. Deposition of TDMAMS was confirmed by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and wetting. ALD of ZnO, including its selectivity on TDMAMS-terminated Si\SiO₂ (Si\SiO₂\TDMAMS), was confirmed by in situ multi-wavelength ellipsometry, ex situ SE, XPS, and/or high-sensitivity/low-energy ion scattering (HS-LEIS). The thermal stability of the TDMAMS resist layer, which is an important parameter for AS-ALD, was investigated by heating Si\SiO₂\TDMAMS in air and nitrogen at 330 °C. ALD of ZnO takes place more readily on Si\SiO₂\TDMAMS heated in the air than in N₂, suggesting greater damage to the surface heated in the air. To better understand the in situ ALD of ZnO on Si\SiO₂\TDMAMS and modified (thermally stressed) forms of it, the ellipsometry results were plotted as the normalized growth per cycle. Even one short pulse of TDMAMS effectively passivates Si\SiO₂. TDMAMS can be a useful, small-molecule inhibitor of ALD of ZnO on Si\SiO₂ surfaces. Full article

Acetylation of glycerol to yield monoacetin (MAT), diacetin (DAT), and triacetin (TAT) over NiO-supported CeO₂ (xNiO/CeO₂) catalysts is reported. The catalysts were synthesized utilizing a sol-gel technique, whereby different quantities of NiO (x = 9, 27, and 45 wt%) were supported onto the CeO₂ substrate, and hexadecyltrimethylammonium bromide (CTABr) served as a porogen. The utilization of EDX elemental mapping analysis confirmed the existence of evenly distributed Ni²⁺ ion and octahedral NiO nanoparticles on the CeO₂ surface through the DRS UV-Vis spectroscopy. The most active catalyst is 27NiO/CeO₂ based on TAT selectivity in the glycerol acetylation with ethanoic acid, attaining 97.6% glycerol conversion with 70.5% selectivity to TAT at 170 °C with a 1:10 glycerol/ethanoic acid molar ratio for 30 min using a non-microwave instant heating reactor. The 27NiO/CeO₂ is reusable without significant decline in catalytic performance after ten consecutive reaction cycles, indicating high structure stability with accessible active acidity. Full article

Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps can lead to a decrease in charge carrier mobility and an increase in recombination rates, thereby ultimately affecting the overall performance of the device. It is therefore important to understand and mitigate the impact of traps on organic semiconductor devices. In this contribution, the influence of the capture and release times of trap states, recombination rates, and the Lorentz force on the net charge of a low-mobility organic semiconductor was determined using the finite element method (FEM) and Hall effect method through numerical simulations. The findings suggest that increasing magnetic fields had a lesser impact on net charge at constant capture and release times of trap states. On the other hand, by increasing the capture time of trap states at a constant magnetic field and fixed release time, the net charge extracted from the semiconductor device increased with increasing capture time. Moreover, the net charge extracted from the semiconductor device was nearly four and eight times greater in the case of the non-Langevin recombination rates of 0.01 and 0.001, respectively, when compared to the Langevin rate. These results imply that the non-Langevin recombination rate can significantly enhance the performance of semiconductor devices, particularly in applications that require efficient charge extraction. These findings pave the way for the development of more efficient and cost-effective electronic devices with improved charge transport properties and higher power conversion efficiencies, thus further opening up new avenues for research and innovation in this area of modern semiconductor technology. Full article

Bioactive glasses (BGs) are promising materials for bone regeneration due to their ability to bond with living bone tissue. However, thermal stability and mechanical properties of BGs need improvement for better clinical performance. In this paper, we present an overview of the influence of different ions on the sintering and crystallization of BGs. Specifically, this review focuses on the impact of thermal treatments on the crystallization of 45S5 and other significant BG compositions. Potential applications of these thermally treated BGs, such as scaffolds, BG-based composites, and thermally sprayed coatings, are explored. Moreover, the substitution of ions has been investigated as a method to enhance the thermal properties of BGs. Notably, zinc, potassium, and strontium have been studied extensively and have demonstrated promising effects on both the thermal and the mechanical properties of BGs. However, it is important to note that research on ion inclusion in BGs is still in its early stages, and further investigation is necessary to fully comprehend the effects of different ions on sintering and crystallization. Therefore, future studies should focus on optimizing the ion substitution method to improve the thermal, mechanical, and even biological properties of BGs, thereby enhancing their potential for various biomedical applications. Full article

Lots of damaged fiber-reinforced plastic (FRP) components are replaced by new components instead of repairing. Furthermore, only very labor-intensive repair methods are available on the market to fully restore the integrity of the structure. This requires a high level of experience or, alternatively, very cost-intensive technology, such as the use of computer tomography and robotics. The high costs and CO₂ emissions caused by the manufacture of FRP components then bear no relation to their service life. The research project IGF-21985 BR “FRP-Repair” aims to solve the named challenges. Using semiconductor oxide catalysts, the matrix can be locally depolymerized by ultraviolet (UV) radiation, and thus removed from the damaged area of the FRP component. Subsequently, the damaged fibers in this area can be detached. By using customized textile repair patches and local thermoset reinfiltration, the repair area is restored. With this process, the fiber structure can be repaired locally with new fibers on the textile level. The repair is similar to the original production of a fiber composite in an infusion process. No additional adhesive material is used. As a result, repaired FRP structures with restored mechanics and a near-original surface can be realized. This article provides an insight into the actual steps of the development of the FRP component repair process using dry textile patches. The empirical investigation of overlapped rovings and UD material showed the expected results. Residual fracture forces of up to 86% could be achieved. The most interesting approach on the roving level was splicing the overlapping fibers. The free ends of the fibers of the patch and part are mechanically bonded. This bond at the textile level is further strengthened by infusion with matrix. Full article

The thermal decomposition path of synthetically and pharmacologically useful hybrid materials was analyzed in inert and oxidizing conditions for the first time and presented in this article. All the imidazoline/dimethyl succinate hybrids (1–5) were studied using the simultaneous thermogravimetry (TG) coupled with Fourier transform infrared spectroscopy (FTIR) and quadrupole mass spectrometry (QMS). It was found that the tested compounds were thermally stable up to 200–208 °C (inert conditions) and up to 191–197 °C (oxidizing conditions). In both furnace atmospheres, their decomposition paths were multi-step processes. At least two major stages (inert conditions) and three major stages (oxidizing conditions) of their decomposition were observed. The first decomposition stage occurred between T_5% and 230–237 °C. It was connected with the breaking of one ester bond. This led to the emission of one methanol molecule and the formation of radicals capable of further radical reactions in both used atmospheres. At the second decomposition stage (T_max2) between 230–237 °C and 370 °C (inert conditions), or at about 360 °C (oxidizing conditions), the cleavage of the second ester bond and N-N and C-C bonds led to the emission of CH₃OH, HCN, N₂, and CO₂ and other radical fragments that reacted with each other to form clusters and large clusters. Heating the tested compounds to a temperature of about 490 °C resulted in the emission of NH₃, HCN, HNCO, aromatic amines, carbonyl fragments, and the residue (T_max2a) in both atmospheres. In oxidizing conditions, the oxidation of the formed residues (T_max3) was related to the production of CO₂, CO, and H₂O. These studies confirmed the same radical decomposition mechanism of the tested compounds both in inert and oxidizing conditions. The antitumor activities and toxicities to normal cells of the imidazoline/dimethyl succinate hybrids were also evaluated. As a result, the two hybrid materials (3 and 5) proved to be the most selective in biological studies, and therefore, they should be utilized in further, more extended in vivo investigations. Full article

The effect of various cleaning methods on coating morphology and their effectiveness in removing organic contaminants has been studied in this research. Bioactive coatings containing titanium oxides and hydroxyapatite (HAP) were obtained through plasma electrolytic oxidation in aqueous electrolytes and molten salts. The cleaning procedure for the coated surface was performed using autoclave (A), ultraviolet light (UV), radio frequency (RF), air plasma (P), and UV-ozone cleaner (O). The samples were characterized using scanning electron microscopy (SEM) with an EDS detector, X-ray photoelectron spectroscopy (XPS), X-ray phase analysis (XRD), and contact angle (CA) measurements. The conducted studies revealed that the samples obtained from molten salt exhibited a finer crystalline structure morphology (275 nm) compared to those obtained from aqueous electrolytes (350 nm). After applying surface cleaning methods, the carbon content decreased from 5.21 at.% to 0.11 at.% (XPS), which directly corresponds to a reduction in organic contaminations and a decrease in the contact angle as follows: A > UV > P > O. This holds true for both coatings obtained in molten salt (25.3° > 19.5° > 10.5° > 7.5°) and coatings obtained in aqueous electrolytes (35.2° > 28.3° > 26.1° > 16.6°). The most effective and moderate cleaning method is ozone treatment. Full article

Micro-fabrication based on structured-beam-assisted Two-Photon Polymerization (2 PP) provides a rapid and flexible method for the manufacture of microstructures with complex morphologies. The tunable Abruptly Autofocusing Vortex (AAFV) beams were designed theoretically and generated experimentally based on a single-phase-only Spatial Light Modulator (SLM). Their specific spatial intensity distributions were further utilized to assist the fabrication of a bowl-shaped Three-Dimensional (3D) micro-trap array via 2 PP with a one-step exposure technique. Finally, the fabricated microstructures act as a novel tool for the trapping and spatial positioning of micro-particles with different diameters, which shows potential applications in fiber optics and cell study. Full article

In this article, a high-performance nanostructured substrate has been fabricated for the ultrasensitive detection of the organic pollutant, Malachite green isothiocyanate (MGITC), in aquatic systems via the Surface Enhanced Raman Spectroscopy (SERS) technique. The chemical dealloying approach has been used to synthesize a three-dimensional nanoporous gold substrate (NPG) consisting of pores and multigrained ligament structures along thickness. The formation of the framework in NPG-5h has been confirmed by SEM with an average ligament size of 65 nm at the narrower neck. Remarkable SERS performance has been achieved by utilizing the NPG-5h substrate for the detection of MGITC, showing a signal enhancement of 7.9 × 10⁹. The SERS substrate also demonstrated an impressively low-detection limit of 10⁻¹⁶ M. The presence of numerous active sites, as well as plasmonic hotspots on the nanoporous surface, can be accredited to the signal amplification via the Localized Surface Plasmon Resonance (LSPR) phenomenon. As a result, SERS detection technology with the fabricated-NPG substrate not only proves to be a simple and effective approach for detecting malachite green but also provides a basis for in situ detection approach of toxic chemicals in aquatic ecosystems. Full article

Manganese sludge, an industrial waste product in the ferroalloy industry, contains various components and holds significant importance for sustainable development through its valorization. This study focuses on characterizing a manganese sludge and investigating its behavior during sulfuric acid leaching. The influence of process conditions, including temperature, acid concentration, liquid to solid ratio, and leaching duration, was examined. The results revealed that Mn, Zn, and K are the main leachable components, and their overall leaching rates increase with increasing temperature, liquid to solid ratio, and time. However, the acid concentration requires optimization. High leaching rates of 90% for Mn, 90% for Zn, and 100% for K were achieved. Moreover, it was found that Pb in the sludge is converted to sulfate during the leaching, which yields a sulfate concentrate rich in PbSO₄. The leaching process for Mn and Zn species appears to follow a second or third order reaction, and the calculation of rate constants indicated that Mn leaching kinetics are two to five times higher than those for Zn. Thermodynamic calculations were employed to evaluate the main chemical reactions occurring during leaching. Full article

Grain boundary engineering (GBE) is considered to be an attractive approach to microstructure control, which significantly enhances the grain-boundary-related properties of face-centered cubic (FCC) metals. During the twinning-related GBE, the microstructures are characterized as abundant special twin boundaries that sufficiently disrupt the connectivity of the random boundary network. However, controlling the grain boundary character distribution (GBCD) is an extremely difficult issue, as it strongly depends on diverse processing parameters. This article provides a comprehensive review of controlling GBCD during the twinning-related GBE of FCC materials. To commence, this review elaborates on the theory of twinning-related GBE, the microscopic mechanisms used in the optimization of GBCD, and the optimization objectives of GBCD. Aiming to achieve control over the GBCD, the influence of the initial microstructure, thermo-mechanical processing (TMP) routes, and thermal deformation parameters on the twinning-related microstructures and associated evolution mechanisms are discussed thoroughly. Especially, the development of twinning-related kinetics models for predicting the evolution of twin density is highlighted. Furthermore, this review addresses the applications of twinning-related GBE in enhancing the mechanical properties and corrosion resistance of FCC materials. Finally, future prospects in terms of controlling the GBCD during twinning-related GBE are proposed. This study will contribute to optimizing the GBCD and designing GBE routes for better grain-boundary-related properties in terms of FCC materials. Full article

Due to its resistance to natural degradation and decomposition, plastic debris perseveres in the environment for centuries. As a lucrative material for packing industries and consumer products, plastics have become one of the major components of municipal solid waste today. The recycling of plastics is becoming difficult due to a lack of resource recovery facilities and a lack of efficient technologies to separate plastics from mixed solid waste streams. This has made oceans the hotspot for the dispersion and accumulation of plastic residues beyond landfills. This article reviews the sources, geographical occurrence, characteristics and recyclability of different types of plastic waste. This article presents a comprehensive summary of promising thermochemical technologies, such as pyrolysis, liquefaction and gasification, for the conversion of single-use plastic wastes to clean fuels. The operating principles, drivers and barriers for plastic-to-fuel technologies via pyrolysis (non-catalytic, catalytic, microwave and plasma), as well as liquefaction and gasification, are thoroughly discussed. Thermochemical co-processing of plastics with other organic waste biomass to produce high-quality fuel and energy products is also elaborated upon. Through this state-of-the-art review, it is suggested that, by investing in the research and development of thermochemical recycling technologies, one of the most pragmatic issues today, i.e., plastics waste management, can be sustainably addressed with a greater worldwide impact. Full article

This paper presents study results of laser processing of W-Cr, WCr/Cr₃C₂ and Cr₃C₂ pre-coats applied on steel substrate in the form of paste. For this study, production parameters were selected to obtain the greatest possible durability of final coatings. Laser processing was carried out using a diode laser machine with a rated power of 3 kW. The laser beam scanning speed was constant at 3 m/min, but variable laser beam powers were used: 600 W, 900 W and 1200 W. Multiple laser tracks with 60% overlapping were used. After remelting the pre-coat with a steel substrate, new coatings were obtained. Following the experiment, microstructure, microhardness, wear, corrosion resistance and chemical composition were investigated. It was found that it is possible to produce W-Cr/Cr₃C₂ coatings through laser processing. These coatings do not have the characteristics of a composite coating; however, increasing the reinforcing phase in the pre-coat positively affects the wear resistance and microhardness. The addition of a reinforcing phase was found to lead to a microhardness of about 750–890 HV01 for 25% and 75% Cr₃C₂, respectively, in comparison to coating without Cr₃C₂. The wear resistance of coatings reinforced by chromium carbide improved more than twofold in reference to the W-Cr coating. Full article

Low-temperature variable-energy electron irradiation was used to induce non-magnetic disorder in a single crystal of a hole-doped iron-based superconductor, Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$, x = 0.80. To avoid systematic errors, the beam energy was adjusted non-consequently for five values between 1.0 and 2.5 MeV when sample resistance was measured in situ at 22 K. For all energies, the resistivity raises linearly with the irradiation fluence suggesting the creation of uncorrelated dilute point-like disorder (confirmed by simulations). The rate of the resistivity increase peaks at energies below 1.5 MeV. Comparison with calculated partial cross-sections points to the predominant creation of defects in the iron sublattice. Simultaneously, superconducting $T_c$, measured separately between the irradiation runs, is monotonically suppressed as expected, since it depends on the total scattering rate, hence on the total cross-section, which is a monotonically increasing function of the energy. Our work experimentally confirms an often-made assumption of the dominant role of the iron sub-lattice in iron-based superconductors. Full article

Hyperbaric oxygen-accelerated corrosion testing (HOACT) is a newly developed method to study in the labor the corrosion behavior of steel bars in concrete. This work aimed to intensively investigate the mechanical properties and microstructures of HOACT-generated corrosion products by means of nano-indentation tests, Raman micro-spectrometry, and scanning electron microscopy. The local elastic modulus and nanohardness varied over wide ranges of 6.8–75.2 GPa and 0.38–4.44 GPa, respectively. Goethite, lepidocrocite, maghemite, magnetite, and akageneite phases were identified in the corrosion products. Most regions of the rust layer were composed of a complex and heterogeneous mix of different phases, while some regions were composed of maghemite or akageneite only. The relationship between the micromechanical properties and typical microstructural features is finally discussed at the micro-scale level. It was found that the porosity of corrosion products can significantly influence their micromechanical properties. Full article

Proton exchange membrane fuel cell (PEMFC) is a renewable energy source rapidly approaching commercial viability. The performance is significantly affected by the transfer of fluid, charges, and heat; gas diffusion layer (GDL) is primarily concerned with the consistent transfer of these components, which are heavily influenced by the material and design. High-efficiency GDL must have excellent thermal conductivity, electrical conductivity, permeability, corrosion resistance, and high mechanical characteristics. The first step in creating a high-performance GDL is selecting the appropriate material. Therefore, titanium is a suitable substitute for steel or carbon due to its high strength-to-weight and superior corrosion resistance. The second crucial parameter is the fabrication method that governs all the properties. This review seeks to comprehend numerous fabrication methods such as tape casting, 3D printing, freeze casting, phase separation technique, and lithography, along with the porosity controller in each process such as partial sintering, input design, ice structure, pore agent, etching time, and mask width. Moreover, other GDL properties are being studied, including microstructure and morphology. In the future, GeoDict simulation is highly recommended for optimizing various GDL properties, as it is frequently used for other porous materials. The approach can save time and energy compared to intensive experimental work. Full article

The continuous development of urban areas around the world led to an increase in construction material use and demand, with concrete seeing significant market uptake. Although significant progress has been made to reduce the environmental impact of concrete, there is still a stringent need for improvement. One of the most widely used methods to reduce the environmental impact of the cement industry and the construction industry alike is the replacement of ordinary Portland cement (OPC) by supplementary cementitious materials (SCM). Aside from by-products of industry, SCMs could also come from natural sources. Taking into account the porous structure of zeolites and their contribution to the improvement of the mechanical and durability properties of cement-based materials, the analysis of pore structure in cement pastes incorporating micronized natural zeolite is deemed necessary. In this research, the OPC was replaced by zeolite in three different percentages: 10%, 20%, and 30% by mass. The evolution of pore structure was investigated by means of nuclear magnetic resonance relaxometry at the curing ages of 1, 7, and 28 days. The microstructure of cement pastes was assessed by scanning electron microscopy investigations at 1, 7, 14, 21, and 28 days. The obtained results show that smaller pore sizes are present in cement pastes containing zeolites during the first 7 days. However, at the age of 28 days, the reference mix exhibits a similar pore structure to the mix containing 10% micronized zeolite due to the presence of larger amounts of hydration products. Increasing the replacement percentage to 30% results in larger pores, as indicated by larger values of the relaxation time. Full article

Tissue regeneration of large bone defects is still a clinical challenge. Bone tissue engineering employs biomimetic strategies to produce graft composite scaffolds that resemble the bone extracellular matrix to guide and promote osteogenic differentiation of the host precursor cells. Aerogel-based bone scaffold preparation methods have been increasingly improved to overcome the difficulties in balancing the need for an open highly porous and hierarchically organized microstructure with compression resistance to withstand bone physiological loads, especially in wet conditions. Moreover, these improved aerogel scaffolds have been implanted in vivo in critical bone defects, in order to test their bone regeneration potential. This review addresses recently published studies on aerogel composite (organic/inorganic)-based scaffolds, having in mind the various cutting-edge technologies and raw biomaterials used, as well as the improvements that are still a challenge in terms of their relevant properties. Finally, the lack of 3D in vitro models of bone tissue for regeneration studies is emphasized, as well as the need for further developments to overcome and minimize the requirement for studies using in vivo animal models. Full article

The nucleation and the growth of misoriented micro-structure components in single crystals depend on various process parameters and alloy compositions. Therefore, in this study, the influence of different cooling rates on carbon-free, as well as carbon-containing, nickel-based superalloys was investigated. Castings were carried out using the Bridgman and Bridgman–Stockbarger techniques under industrial and laboratory conditions, respectively, to analyze the impact of temperature gradients and withdrawing rates on six alloy compositions. Here, it was confirmed that eutectics could assume a random crystallographic orientation due to homogeneous nucleation in the residual melt. In carbon-containing alloys, eutectics also nucleated at low surface-to-volume ratio carbides due to the accumulation of eutectic-forming elements around the carbide. This mechanism occurred in alloys with high carbon contents and at low cooling rates. Furthermore, micro-stray grains were formed by the closure of residual melt in Chinese-script-shaped carbides. If the carbide structure was open in the growth direction, they could expand into the interdendritic region. Eutectics additionally nucleated on these micro-stray grains and consequently had a different crystallographic orientation compared with the single crystal. In conclusion, this study revealed the process parameters that induced the formation of misoriented micro-structures, which prevented the formation of these solidification defects by optimizing the cooling rate and the alloy composition. Full article