Search Results (361)

Construction wood has a high economic value, and its construction waste also has multiple consumption values. Natural wood has many advantages, such as thermal, environmental, and esthetic properties; however, wood sourced from artificial fast-growing forests is found to be deficient in mechanical strength. This shortcoming makes it less competitive in certain applications, leading many markets to remain dominated by non-renewable materials. To address this issue, various modification methods have been explored, with a focus on enhancing the plasticity and strength of wood. Studies have shown that hydrogen bonds in the internal structure of wood have a significant impact on its operational performance. Whether it is organic modification, inorganic modification, or a combination thereof, these methods will lead to a change in the shape of the hydrogen bond network between the components of the wood or will affect the process of its breaking and recombination, while increasing the formation of hydrogen bonds and related molecular synergistic effects and improving the overall operational performance of the wood. These modification methods not only increase productivity and meet the needs of efficient use and sustainable environmental protection but also elevate the wood industry to a higher level of technological advancement. This paper reviews the role of hydrogen bonding in wood modification, summarizes the mechanisms by which organic, inorganic, and composite modification methods regulate hydrogen bond networks, discusses their impacts on wood mechanical properties, dimensional stability, and environmental sustainability, and provides an important resource for future research and development. Full article

Two-component dental materials are commonly used by the dentist for various applications (cementation of indirect restorations, filling of a cavity without layering, etc.). These materials are cured by redox polymerization. The (hydro)peroxide/thiourea/copper salt redox initiator system is well established and can be found in a wide range of commercially available dental materials. The thiourea is a key component of the initiator system. This study explores the influence of the nature of the thiourea reducing agent on the reactivity and efficiency of redox initiator systems. In this work, six different thiourea structures were investigated, in combination with copper(II) acetylacetonate and cumene hydroperoxide (CHP), to understand their impact on polymerization kinetics and mechanical properties of methacrylate-based materials. Various experimental techniques, including mass spectrometry (MS) and spectroscopic analyses, were employed to elucidate the underlying mechanisms governing these redox systems. The results highlight that thiourea plays a dual role, acting both as a reducing agent and as a ligand in copper complexes, affecting radical generation and polymerization efficiency. Structural modifications of thiourea significantly influence the initiation process, demonstrating that reactivity is governed by a combination of factors rather than a single property. Self-cure dental flowable composites exhibiting excellent flexural strength (>100 MPa) and modulus (>6000 MPa) were obtained using hexanoyl thiourea, N-benzoylthiourea, or 1-(pyridin-2-yl)thiourea as a reducing agent. The adjustment of the Cu(acac)₂ enables to properly set the working time in the range of 100 to 200 s. These findings provide valuable insights into the design of the next generation of redox initiating systems for mild and safe polymerization conditions. Full article

The use of widespread and inexpensive clay minerals as adsorptive agents, as well as materials obtained by their chemical modification, can contribute to the solution of the problem of environmental pollution with antibiotics. This review considers the structural features of various natural clay minerals and the effect of these features on their sorption capacity. Based on the analysis of available papers (over the last 15 years, also including some fundamental basics over the last 20–30 years), it has been established that the main property of an antibiotic molecule affecting the ability to be adsorbed by a clay mineral is the hydrophilicity of the organic substance molecule. The leading properties that determine the ability of clays to adsorb antibiotics are the charge and area of their surfaces. The ability of antibiotic molecules to protonate and a partial change in the edge charge of mineral layers is determined by the acidity of the sorption solution. In addition, empirical evidence is provided that the most important factors affecting adsorption are the ionic strength of the sorption solution, the concentration of the adsorbent and adsorbate, and the interaction temperature. The diversity of the composition, structure, and properties of clay minerals allows them to be effective sorbents for a wide range of antibiotics. Full article

Flying wing Unmanned Aerial Vehicles (UAVs) are an interesting flight configuration, considering its benefits over aerodynamic, structural and added stealth aspects. The existing configurations are thoroughly studied from the literature survey and useful observations with respect to design and analysis are obtained. The proposed design method includes distinct calculations of the UAV and modelling using 3D experience. The created innovative models are simulated with the help of computational fluid dynamics techniques in ANSYS Fluent to obtain the aerodynamic parameters such as forces, pressure and velocity. The optimization process continues to add more desired modifications to the model, to finalize the best design of flying wing frame for the chosen application and mission profile. In total, nine models are developed starting with the base model, then leading to the conventional, advanced and nature inspired configurations such as the falcon and dragonfly models, as it has an added advantage of producing high maneuverability and lift. Following this, fluid structure interaction analysis has been performed for the best performing configurations, resulting in the determination of variations in the structural behavior with the imposition of advanced composite materials, namely, boron, Kevlar, glass and carbon fiber-reinforced polymers. In addition to this, a hybrid material is designed by combining two composites that resulted in superior material performance when imposed. Control dynamic study is performed for the maneuvers planned as per mission profile, to ensure stability during flight. All the resulting parameters obtained are compared with one another to choose the best frame of the flying wing body, along with the optimum material to be utilized for future analysis and development. Full article

Wood is a green and renewable bio-based building material, but its hygroscopicity affects its dimensional stability, limiting its use in construction. Chemical modification can improve its properties, yet its effectiveness depends on wood permeability and traditional modifiers. This study first used a deep eutectic solvent (DES) to boost the permeability of North American alder wood. Then, methyl trimethoxysilane was impregnated under supercritical carbon dioxide (SCI), pressure (PI), vacuum (VI), and atmospheric pressure (AI) conditions. DES treatment damaged the cell structure, increasing wood permeability. Silane was deposited and polymerized in the cell lumen, chemically bonding with cell-wall components, filling walls and pits, and thickening walls. The VI group had the highest absolute density (0.59 g/cm³, +36.6%) and the lowest moisture absorption (4.4%, −33.3%). The AI group had the highest ASE (25%). The PI group showed the highest surface hardness (RL, 2592 N) and a water contact angle of 131.9°, much higher than natural wood. Overall, the VI group had the best performance. Silane reacts with cellulose, hemicellulose, and lignin in wood via hydrolysis and hydroxyl bonding, forming stable bonds that enhance the treated wood’s hydrophobicity, dimensional stability, and surface hardness. Full article

The dynamic control of vibrations in skyscrapers is a critical consideration in sustainable building design, particularly in response to environmental excitations such as wind impact or seismic activity. Effective vibration neutralisation plays a crucial role in providing the safety of high-rise buildings. This research introduces an innovative concept for an active vibration damper that operates based on fluid dynamic transport to adaptively alter a skyscraper’s natural frequency, thereby counteracting resonant vibrations. A distinctive feature of this system is an adjustable-length cable mechanism, allowing for the dynamic modification of the pendulum’s effective length in real time. The structure, based on cable length adjustment, enables the PTMD to precisely tune its natural frequency to variable excitation conditions, thereby improving damping during transient or resonance phenomena of the building’s dynamic behaviour. A comprehensive mathematical model based on Lagrangian mechanics outlines the governing equations for this system, capturing the interactions between pendulum motion, fluid flow, and the damping forces necessary to maintain stability. Simulation analyses examine the role of initial excitation frequency and variable damping coefficients, revealing critical insights into optimal damper performance under varied structural conditions. The findings indicate that the proposed pendulum damper effectively mitigates resonance risks, paving the way for sustainable skyscraper design through enhanced structural adaptability and resilience. This adaptive PTMD, featuring an adjustable-length cable, provides a solution for creating safe and energy-efficient skyscraper designs, aligning with sustainable architectural practices and advancing future trends in vibration management technology. The study presented in this article supports the development of modern skyscraper design, with a focus on dynamic vibration control for sustainability and structural safety. It combines advanced numerical modelling, data-driven control algorithms, and experimental validation. From a sustainability perspective, the proposed PTMD system reduces the need for oversized structural components by providing adaptive, efficient damping, thereby lowering material consumption and embedded carbon. Through dynamically retuning structural stiffness and mass, the proposed PTMD enhances resilience and energy efficiency in skyscrapers, lowers lifetime energy use associated with passive damping devices, and enhances occupant comfort. This aligns with global sustainability objectives and new-generation building standards. Full article

The unique structures and properties of natural organisms provide abundant inspiration for surface modification research in materials science. In this paper, the tribological advantages of radial ribs found on shell surfaces were combined with laser cladding to address challenges in material surface strengthening. Laser cladding technology was used to fabricate bionic units on the surface of 20CrMnTi steel. The alloy powder consisted of a Ni-based alloy with added WC particles. The influence of laser power (1.0 kW–3.0 kW) on the dimensions, microstructure, hardness, surface roughness, and tribological properties of the bionic units was investigated to enhance the tribological performance of the Ni60/WC bionic unit. The microstructure, phase composition, hardness, and tribological behavior of the bionic units were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), a microhardness tester, and a wear tester. Experimental results show that the dimensions of the bionic units increased with laser power. However, beyond a certain threshold, the growth rate of the width and height gradually slowed due to heat conduction and edge cooling effects. The microstructure primarily consisted of equiaxed and dendritic crystals, with grain refinement observed at higher laser powers. The addition of WC resulted in average hardness values of 791 HV_0.2, 819 HV_0.2, 835 HV_0.2, and 848 HV_0.2 across the samples. This enhancement in hardness was attributed to dispersion strengthening and grain refinement. Increasing the laser power also reduced the surface roughness of the bionic units, though excessively high laser power led to a roughness increase. The presence of WC altered the wear mechanism of the bionic units. Compared to the wear observed in the N60 sample, the wear amount of the WC-containing samples decreased by 73.7%, 142.1%, 157.5%, and 263.1%, respectively. Hard WC particles played a decisive role in enhancing tribological performance of the bionic unit. Full article

Cartilage damage, particularly in the knee joint, presents a significant challenge in regenerative medicine due to its limited capacity for self-repair. Conventional treatments like microfracture surgery, autologous chondrocyte implantation (ACI), and osteochondral allografts often fall short, particularly in cases of larger defects or degenerative conditions. This has led to a growing interest in tissue engineering approaches that utilize biomaterial scaffolds to support cartilage regeneration. Among the many materials explored, chitosan—a naturally derived polysaccharide—has gained attention for its biocompatibility, biodegradability, and structural resemblance to the extracellular matrix (ECM) of cartilage. Recent advances in scaffold design have focused on modifying chitosan to improve its mechanical properties and enhance its biological performance. These modifications include chemical crosslinking, the incorporation of bioactive molecules, and the development of composite formulations. Such enhancements have allowed chitosan-based scaffolds to better support mesenchymal stem cell (MSC) differentiation into chondrocytes, paving the way for improved regenerative strategies. This review explores the latest progress in chitosan scaffold fabrication, preclinical findings, and the transition toward clinical applications. It also discusses the challenges that need to be addressed, such as mechanical stability, degradation rates, and the successful translation of research into viable therapeutic solutions. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

Since 2010, BiCuSeO has emerged as a captivating subject of investigation within the realm of thermoelectric materials. Its allure lies in a remarkable confluence of characteristics: a distinctive natural super-lattice structure, an elevated Seebeck coefficient, and a low thermal conductivity, all of which have collectively piqued the intense interest of scientists worldwide. Over the subsequent eight-year period, an extensive array of research endeavors has been meticulously carried out, delving deep into the multifaceted properties of BiCuSeO and exploring avenues for performance enhancement. In this comprehensive review, we embark on a detailed exploration of the fundamental properties of BiCuSeO, encompassing its preparation methodologies, as well as its thermoelectric and mechanical attributes. A thorough synthesis of diverse strategies for optimizing the composition and structure of BiCuSeO is presented, elucidating how these modifications contribute to the enhancement of its thermoelectric and mechanical performance. Finally, the current state of research on N-type BiCuSeO is systematically summarized, offering a panoramic view of the advancements and challenges in this particular area. Full article

Research on bionic superhydrophobic surfaces draws inspiration from the microstructures and wetting mechanisms of natural organisms such as lotus leaves, water striders, and butterfly wings, offering innovative approaches for developing artificial functional surfaces. By synergistically combining micro/nano hierarchical structures with low surface energy chemical modifications, researchers have devised various fabrication strategies—including laser etching, sol-gel processes, electrochemical deposition, and molecular self-assembly—to achieve superhydrophobic surfaces characterized by contact angles exceeding 150° and sliding angles below 5°. These technologies have found widespread applications in self-cleaning architectural coatings, efficient oil–water separation membranes, anti-icing materials for aviation, and anti-biofouling medical devices. This article begins by examining natural organisms exhibiting superhydrophobic properties, elucidating the principles underlying their surface structures and the wetting states of droplets on solid surfaces. Subsequently, it categorizes and highlights key fabrication methods and application domains of superhydrophobic surfaces, providing an in-depth and comprehensive discussion. Full article

Bioelectronics for wearable and implantable biomedical devices has attracted significant attention due to its potential for continuous health monitoring, early disease diagnosis, and real-time therapeutic interventions. Among the various materials explored for bioelectronic applications, hydrogels derived from natural biopolymers have emerged as highly promising candidates, owing to their inherent biocompatibility, mechanical compliance akin to biological tissues, and tunable structural properties. This review provides a comprehensive overview of recent advancements in the design and application of protein-based hydrogels, including gelatin, collagen, silk fibroin, and gluten, as well as carbohydrate-based hydrogels such as chitosan, cellulose, alginate, and starch. Particular emphasis is placed on elucidating their intrinsic material characteristics, modification strategies to improve electrical and mechanical performance, and their applicability for bioelectronic interfaces. The review further explores their diverse applications in physiological and biochemical signal sensing, bioelectric signal recording, and electrical stimulation. Finally, current challenges and future perspectives are discussed to guide the ongoing innovation of hydrogel-based systems for next-generation bioelectronic technologies. Full article

Recycling construction and demolition (C&D) waste into recycled aggregate (RA) and recycled aggregate concrete (RAC) is conducive to natural resource conservation and industry decarbonization, which have been attracting much attention from the community. This paper aims to present a synthesis of recent scientific insights on RA and RAC by conducting a systematic review of the latest advances in their properties, test techniques, modeling, modification and improvement, as well as applications. Over 100 papers published in the past three years were examined, extracting enlightening information and recommendations for engineering. The review shows that consistent conclusions have been drawn about the physical properties in that RA can reduce the workability and the setting time of fresh RAC and increase the porosity of hardened RAC. Its impact on drying and autogenous shrinkage is governed by its size and the strength of the parent concrete. RA generally acts negatively on the durability and mechanical properties of concrete, but such effects remain controversial as many opposite observations have been reported. Apart from the commonly used multiscale test techniques, real-time monitoring also plays an important role in the investigation of deformation and fracture processes. Analytical models for RAC were usually modified from the existing models for NAC or established through regression analysis, while for numerical models, the distribution of attached mortar should be considered to improve their accuracy. Machine learning models are effective in predicting RAC properties. Modification of RA can be implemented by either removing or strengthening the attached mortar, while the modification of RAC is mainly achieved by improving its microstructure. Current exploration of RAC applications mainly focuses on the optimization of concrete design and mix procedures, structural components, as well as multifunctional construction materials, revealing the room for its further exploitation in the industry. Full article

This study presents a novel Basalt-based grafted graphitic carbon nitride composite (Basalt–MTES/g-C₃N₄) for the efficient pretreatment of Cr(VI) in ethylene wastewater. The composite was synthesized by the acid purification of natural Basalt, surface modification with hydroxymethyl triethoxysilane (MTES), and the subsequent grafting of g-C₃N₄. Characterization confirmed the uniform distribution of nano-sized g-C₃N₄ particles on a Basalt surface with intact chemical bonding, where 82.63% of melamine participated in g-C₃N₄ crystallization. The material exhibited a high specific surface area (403.55 m²/g) and mesoporous structure (34.29 nm). Acidic conditions promoted the protonation of amino groups in g-C₃N₄, significantly enhancing Cr(VI) adsorption via ion exchange. Adsorption kinetics followed the pseudo-second-order model, while isotherm data fitted the Langmuir monolayer adsorption mechanism. The composite achieved 97% Cr(VI) recovery through chromatographic extraction and retained 96.87% removal efficiency after five regeneration cycles. This work demonstrates a cost-effective, recyclable green pretreatment material for high-sensitivity Cr(VI) monitoring in ethylene industry wastewater, offering dual benefits in environmental remediation and regulatory compliance. The design synergizes natural Basalt’s stability with g-C₃N₄’s adsorption affinity, showing practical potential for sustainable wastewater treatment technologies. Full article

Due to the depletion of hydrocarbon resources worldwide, intensive research is being conducted to identify alternative energy carriers. Hydrogen has emerged as a promising candidate due to its high energy density and environmentally friendly nature. However, large-scale implementation of hydrogen energy is hindered by the lack of safe, efficient, and cost-effective storage methods. Among the various materials studied for solid-state hydrogen storage, boron nitride (BN)-based compounds have attracted significant attention owing to their high thermal stability, tunable morphology, and potential for physisorption-based storage. This review focuses on recent advances in the synthesis, functionalization, and structural optimization of BN-based materials, including nanotubes, nanosheets, porous frameworks, and chemically modified BN. Although other boron-containing hydrides such as LiBH₄, Mg(BH₄)₂, and closo-borates are briefly mentioned for comparison, the primary emphasis is placed on BN-related systems. This paper discusses various modification strategies aimed at enhancing hydrogen uptake and reversibility, offering insights into the future potential of BN-based materials in hydrogen storage technologies. Full article