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•Selective inactivation method first applied in the biochar/persulfate system.•Ketone groups have proved to be the active sites for non-radical pathway.•Inorganic component might be ...able to simulate persulfate to produce O2− and 1O2.•Acid treatment is an effective means to enhance the stability of bone char.
Recently, biochar was frequently applied in catalysis field, and it has been regarded as an efficient carbon-rich material to degrade organic pollutants in water. Various functional structures of biochar (such as pore structure, oxygen-containing groups and, defects) have been reported to be valid in catalysis. Whereas the complexity of biochar structure and composition hinders the further exploration of specific functions of biochar. To address this problem, selective inactivation experiment was first involved to investigate the role of oxygen-containing groups in catalysis. In this study, swine bone derived biochar (BBC) was adopt as catalyst in persulfate (PS) activation system to degrade acetaminophen (ACT). Both non-radical and radical pathway worked in BBC/PS system. ACT could be completely degraded in 60 min, and the removal rate could reach 0.3111 min−1. The results showed that the ketone groups on the BBC were the primary active sites of PS/BBC system and it played a major role in non-radical pathway (electron transfer pathway), and it might act as the active sites to produce OH in BBC/PS system. Besides, the COOH and OH on BBC might be beneficial to radical pathway, which can help to generate OH and SO4−. Interestingly, residual hydroxyapatite and defects in BBC might be able to stimulate PS to produce O2− and 1O2. With the development of increasingly precise biochar synthesis techniques, these verdicts give evidence to further oriented synthesis of biochar.
Origami and kirigami, the ancient techniques for making paper works of art, also provide inspiration for routes to structural platforms in engineering applications, including foldable solar panels, ...retractable roofs, deployable sunshields, and many others. Recent work demonstrates the utility of the methods of origami/kirigami and conceptually related schemes in cutting, folding, and buckling in the construction of devices for emerging classes of technologies, with examples in mechanical/optical metamaterials, stretchable/conformable electronics, micro/nanoscale biosensors, and large‐amplitude actuators. Specific notable progress is in the deployment of functional materials such as single‐crystal silicon, shape memory polymers, energy‐storage materials, and graphene into elaborate 3D micro and nanoscale architectures. This review highlights some of the most important developments in this field, with a focus on routes to assembly that apply across a range of length scales and with advanced materials of relevance to practical applications.
Origami and kirigami, ancient techniques for making paper artworks, enable many nontraditional, unusual applications in engineering and scientific fields. This review highlights the latest progress in the research on the origami and kirigami assembly of 3D structures in advanced materials at macroscale to microscale and nanoscale, focusing on assembly approaches at each length scale and/or the newly accessible unusual applications.
•A review on the fabrication of surface functional structure for enhancing the performance of heat pipes.•The applications of heat pipes with different wick structures are introduced.•The ...manufacturing technologies of surface functional structures and their applications are summarized.•The influence of surface functional structure on heat transfer performance of heat pipes is discussed.
Heat pipes, as efficient two-phase heat-transfer devices, are widely applied in thermal management of electronics for their remarkable thermal conductivity and high reliability. However, the development of high-performance, miniaturization and high-density packaging of electronics demands a solution to thermal management of large heat flux in limited space, which requires heat pipes with stronger heat transfer performances. As the core component of heat pipes, wick provides the capillary pressure to drive the closed circulation of the working fluid and an interface for the liquid–vapor phase changes, which determines the start-up performance and heat transfer capacity of heat pipes. Capillary pressure of wicks and thermal performance of heat pipes can be enhanced by fabricating functional structures on the surface of wicks. This paper presents a comprehensive review on the recent developments and applications of surface functional structures of heat pipe wicks. The applications of heat pipes with different wick structures are introduced, and the manufacturing technologies of surface functional structures are summarized and compared. Furthermore, the fabrication of surface functional structures used for various wicks are reviewed and analysed in detail. Finally, the challenges affecting the development of surface functional structures are outlined, and recommendations for future research are presented.
Additive manufacturing (AM) is developing rapidly due to its flexibility in producing complex geometries and tailored material compositions. However, AM processes are characterized by intrinsic ...limitations concerning their resolution and surface finish, which are related to the layer‐by‐layer stacking process. Herein, a self‐organization process is promoted as an approach to improve surface quality and achieve optimization of 3D minimal surface lightweight structures. The self‐organization is activated after the powder bed 3D printing process via local melting, thereby allowing surface tension‐driven viscous flow. The surface roughness Ra (arithmetic average of the roughness profile) could be decreased by a factor of 1000 and transparent lenses and complex gyroid structures could be produced for demonstration. The concept of self‐organization is further elaborated by incorporating external magnetic fields to intentionally manipulate magnetic particles, which are mixed with the polymer before printing and self‐organization. This concept can be applied to develop programmable materials with specific microtextures responding to the external physical conditions.
Herein, a self‐organization postprocess that can remarkably improve the surface quality and density from the powder bed 3D‐printed porous matrix is presented, while achieving topological optimization of minimal surface lightweight structures. Self‐organization is realized by local melting which enables a viscous flow driven by surface tension. Consequently a gyroid structure with an optical transparent area in the center is achieved.
Natural organisms have evolved a series of versatile functional biomaterials and structures to cope with survival crises in their living environment, exhibiting outstanding properties such as ...superhydrophobicity, anisotropy, and mechanical reinforcement, which have provided abundant inspiration for the design and fabrication of next‐generation multi‐functional devices. However, the lack of available materials and limitations of traditional manufacturing methods for complex multiscale structures have hindered the progress in bio‐inspired manufacturing of functional structures. As a revolutionary emerging manufacturing technology, additive manufacturing (i.e., 3D printing) offers high design flexibility and manufacturing freedom, providing the potential for the fabrication of intricate, multiscale, hierarchical, and multi‐material structures. Herein, a comprehensive review of current 3D printing of surface/interface structures, covering the applied materials, designs, and functional applications is provided. Several bio‐inspired surface structures that have been created using 3D printing technology are highlighted and categorized based on their specific properties and applications, some properties can be applied to multiple applications. The optimized designs of these 3D‐printed bio‐inspired surfaces offer a promising prospect of low‐cost, high efficiency, and excellent performance. Finally, challenges and opportunities in field of fabricating functional surface/interface with more versatile functional material, refined structural design, and better cost‐effective are discussed.
Several 3D printed bio‐inspired surface structures are demonstrated in aspect of the applied materials, functional designs, and various applications. Based on the applications, the design of the 3D‐printed structures can be categorized as superhydrophobic structures, structures for drag force reduction, microscale surface structures with anisotropic water transport, surfaces for water collection and oil/water separation, and micro‐needle structures. The optimized designs of the 3D‐printed bio‐inspired surface structures will have a promising potential as the next generation of multi‐functional materials with low‐cost, high efficiency, and excellent performance.
Smart honeycombs are becoming the novel structural strategy for next‐generation devices and equipments. Unfortunately, traditional surface‐coating, structural immersing, and 3D printing approaches ...still face significant challenges in combining structural customization and performance multifunctionality. Herein, a brand‐new processing strategy is developed to construct graphene‐based smart honeycombs by stacking and deploying laser‐induced graphene (LIG) layers with alternatively inserted adhesives. Through tuning key parameters, various LIG‐enabled smart honeycombs (LIG‐HC) can be assembled with scalable areal dimension and thickness, variable cell sizes and shapes, as well as patternable graphene clusters. By further understanding the process‐dependent structural stability and electrical conductivity, multifunctional characteristics are systematically explored, including anisotropic mechanical, electrical, piezoresistive, and electromagnetic performance. To finally demonstrate the unique honeycomb multifunctionally applied in fields of aviation, an intelligent LIG‐HC enabled aircraft‐wing model is representatively constructed for performing anti‐/de‐icing, high‐temperature warning, flame retardancy, pressure and vibration monitoring, as well as electromagnetic shielding and stealth.
Laser‐induced graphene (LIG) enabled smart honeycombs (LIG‐HC) are creatively developed through the assembly of stackable and deployable LIG layers. With programmable process toward the construction of LIG‐HC with scalable dimension, variable cell‐structures and patternable graphene‐clusters, an intelligent LIG‐HC aircraft‐wing model is demonstrated for reflecting its multifunctionality including anti‐/de‐icing, high‐temperature warning, flame retardancy, pressure/vibration sensing, and electromagnetic shielding and stealth.
Touch control intention recognition is an important direction for the future development of human–machine interactions (HMIs). However, the implementation of parallel‐sensing functional modules ...generally requires a combination of different logical blocks and control circuits, which results in regional redundancy, redundant data, and low efficiency. Here, a location‐and‐pressure intelligent tactile sensor (LPI tactile sensor) unprecedentedly combined with sensing, computing, and logic is proposed, enabling efficient and ultrahigh‐resolution action–intention interaction. The LPI tactile sensor eliminates the need for data transfer among the functional units through the core integration design of the layered structure. It actuates in‐sensor perception through feature transmission, fusion, and differentiation, thereby revolutionizing the traditional von Neumann architecture. While greatly simplifying the data dimensionality, the LPI tactile sensor achieves outstanding resolution sensing in both location (<400 µm) and pressure (75 Pa). Synchronous feature fusion and decoding support the high‐fidelity recognition of action and combinatorial logic intentions. Benefiting from location and pressure synergy, the LPI tactile sensor demonstrates robust privacy as an encrypted password device and interaction intelligence through pressure enhancement. It can recognize continuous touch actions in real time, map real intentions to target events, and promote accurate and efficient intention‐driven HMIs.
A location and pressure intelligent tactile sensor with an innovative layered structure is developed to realize efficient ultrahigh resolution intention interaction through in‐sensor sensing, computing, and logic. It achieves outstanding resolution in location (<400 µm) and pressure (75 Pa) with minimal data dimension. Various touch‐intention interactions are explored in logic, encryption, and interaction intelligence.
Rapid progress in material science and nanotechnology has led to the development of the shape memory alloys (SMA) and the shape memory polymers (SMP) based functional multilayered structures that, ...due to their capability to achieve the properties not feasible by most natural materials, have attracted a significant attention from the scientific community. These shape memory materials can sustain large deformations, which can be recovered once the appropriate value of an external stimulus is applied. Moreover, the SMAs and SMPs can be reprogrammed to meet several desired functional properties. As a result, SMAs and SMPs multilayered structures benefit from the unprecedented physical and material properties such as the shape memory effect, superelasticity, large displacement actuation, changeable mechanical properties, and the high energy density. They hold promises in the design of advanced functional micro- and nano-electro-mechanical systems (MEMS/NEMS). In this review, we discuss the recent understanding and progress in the fields of the SMAs and SMPs. Particular attention will be given to the existing challenges, critical issues, limitations, and achievements in the preparation and characterization of the SMPs and NiTi-based SMAs thin films, and their heterostructures for MEMS/NEMS applications including both experimental and computational approaches. Examples of the recent MEMS/NEMS devices utilizing the unique properties of SMAs and SMPs such as micropumps, microsensors or tunable metamaterial resonators are highlighted. In addition, we also introduce the prospective future research directions in the fields of SMAs and SMPs for the nanotechnology applications.
By increasing the number of functions a structure performs it is possible to save weight and volume on a systems level. Ion-insertion in carbon fibres (CFs) is a way to create multifunctional ...structures for energy storage, morphing, and strain-sensing. Previous studies have focussed on lithium- and sodium-insertion to create multifunctionality. However, with a larger ionic radius and a chemistry more amenable to insertion in polyacrylonitrile (PAN)-based CFs, potassium-insertion is a promising way forward. Here, a study is conducted to examine potassium-insertion in intermediate modulus PAN-based CFs for multifunctionality. Electrochemical cycling shows a maximum reversible capacity of 170 mAh/g, with ex-situ mechanical testing showing a small impact on the CFs’ mechanical properties post-cycling. Operando measurements show a maximum reversible CF expansion during potassium-insertion of 0.24%, and analytical modelling illustrates that such strains can generate significant deformations in a morphing structure. A voltage-strain coupling of 0.26 V/unit strain is also found. Results are compared with previous work on lithium- and sodium-insertion, with the conclusion that potassium-insertion is more promising than sodium-insertion, but less so than lithium-insertion for multifunctional structures.
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In this study, bioactive glass nanoparticles (BGNPs) with an average diameter of less than 10 nm were synthesized using a sol-gel method and then characterized by transmission electron microscopy ...(TEM), differential scanning calorimetric (DSC), Fourier transforms infrared spectroscopy (FTIR), and x-ray spectroscopy (XRD). Afterward, three dimensional (3D)-printed polycaprolactone (PCL) scaffolds along with fused deposition modeling (FDM) were incorporated with BGNPs, and the surface of the composite constructs was then functionalized by coating with the gelatin methacryloyl (GelMA) under UV irradiation. Field emission scanning electron microscopy micrographs demonstrated the interconnected porous microstructure with an average pore diameter of 260 µm and homogeneous distribution of BGNPs. Therefore, no noticeable shrinkage was observed in 3D-printed scaffolds compared with the computer-designed file. Besides, the surface was uniformly covered by GelMA, and no effect of surface modification was observed on the microstructure while surface roughness increased. The addition of the BGNPs the to PCL scaffolds showed a slight change in pore size and porosity; however, it increased surface roughness. According to mechanical analysis, the compression strength of the scaffolds was increased by the BGNPs addition and surface modification. Also, a reduction was observed in the absorption capacity and biodegradation of scaffolds in phosphate-buffered saline media after the incorporation of BGNPs, while the presence of the GelMA layer increased the swelling potential and stability of the composite matrixes. Moreover, the capability of inducing bio-mineralization of hydroxyapatite-like layers, as a function of BGNPs content, was proven by FE-SEM micrographs, EDX spectra, and x-ray diffraction spectra (XRD) after soaking the obtained samples in concentrated simulated body fluid. A higher potential of the modified constructs to interact with the aqueous media led to better precipitation of minerals. According to
in-vitro
assays, the modified scaffolds can provide a suitable surface for the attachment and spreading of the bone marrow mesenchymal stem cells (BMSCs). Furthermore, the number of the proliferated cells confirms the biocompatibility of the scaffolds, especially after a modification process. Cell differentiation was verified by alkaline phosphatase activity as well as the expression of osteogenic genes such as osteocalcin and osteopontin. Accordingly, the scaffolds showed an initial potential for reconstruction of the injured bone.
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