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ABSTRACTThis paper tackles high computational complexity in using Euclidean distance for residential load profiles (RLPs) similarity by proposing a three-stage incremental segmented slope clustering framework. The first two stages involve static clustering, where we obtain typical residential load profiles through piecewise slope clustering. In the third stage, dynamic clustering is performed based on the slope similarity of RLPs. This method enhances clustering performance and reduces computation cost, outperforming various benchmarks, with simulation results confirming the framework's effectiveness.

The 1420 Al–Li alloy has been widely used in the aerospace field. To investigate the hot workability of the alloy, a series of hot compression tests were carried out on the spray-formed alloy in the temperature range of 300°C–450 °C with strain rates of 0.0001s−1-10s−1. First, an improved Johnson-Cook model was developed by considering the coupling effect of strain, strain rate, and temperature, and the prediction error of the model was reduced to 5.3 %. Subsequently, processing maps with various strains were established. In addition, the microstructural evolution under various deformation conditions was systematically studied using the electron backscatter diffraction (EBSD) technique. The alloy exhibited uniform deformation under the synergistic effect of the continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms. Finally, the feasible hot working windows were identified as 425°C–450°C and 0.01s−1-0.1s−1based on processing maps and microstructural evolution results. This work could offer comprehensive guidance for the hot working process of 1420 Al–Li alloy from both the macro and the micro aspects.

Here, we report a novel visible-light-driven I−doped Bi2O2CO3nano-sheet photocatalyst synthesized viaa facile ion exchange route at room temperature. This obtained Bi2O2CO3nano-sheet with I−doping shows several advantages. The specific surface area of I0.875-Bi2O2CO3is 2.16 times higher than that of Bi2O2CO3, providing more catalytic sites for the degradation reactions. Moreover, a 3.2 times photocurrent enhancement is observed in I0.875-Bi2O2CO3compared with Bi2O2CO3, producing more photogenerated electron-hole pairs for degradation. The synergistic effect between texture property and photoelectric effect boosts the removal of organic pollutants. Under visible light illumination, I0.875-Bi2O2CO3displays superior photocatalytic performance for the degradation of methyl orange (MO) and phenol. Notably, a phenol degradation rate, 88%, is achieved by I0.875-Bi2O2CO3with illuminating for 60 min, which is about 29 times higher than that of pristine Bi2O2CO3. This finding may provide an opportunity to develop a promising I−doped catalyst for organic pollutants removal.

The mechanical properties and microstructure evolution of the spray formed 2195 alloy extruded sheet at warm forming temperatures (100 °C–300 °C) were systematically investigated in this work. The results showed that the yield strength and ultimate tensile strength of the alloy declined obviously as the temperature rose, while the elongation increased initially and then decreased. With an increase in the strain rate, the yield strength and elongation of the alloy decreased, whereas the tensile strength increased. In addition, the tensile fracture behavior of the alloy was significantly affected by the temperature, and the fracture mode gradually shifted from intergranular fracture to ductile fracture as the temperature rose. The softening mechanism of the alloy was dominated by the dynamic recovery at different temperatures, and a certain degree of dynamic recrystallization was observed at 300 °C, which resulted in a dramatic decrease in the dislocation density of the alloy. Moreover, with an increase in temperature, coarser grains also appeared. Besides, the dislocation density and grain size of the alloy decreased initially and then increased with an increasing strain rate. Finally, it was found that the texture component of the alloy under different test conditions was mainly composed of deformation textures such as Brass and S. With the temperature increasing, the alloy showed a decrease first and then an increase in the texture strength, while the texture strength of the alloy increased continuously as the strain rate increased.

The rotator cuff tear has emerged as a significant global health concern. However, existing therapies fail to fully restore the intricate bone-to-tendon gradients, resulting in compromised biomechanical functionalities of the reconstructed enthesis tissues. Herein, a tri-layered core–shell microfibrous scaffold with layer-specific growth factors (GFs) release is developed using coaxial electrohydrodynamic (EHD) printing for in situ cell recruitment and differentiation to facilitate gradient enthesis tissue repair. Stromal cell-derived factor-1 (SDF-1) is loaded in the shell, while basic fibroblast GF, transforming GF-beta, and bone morphogenetic protein-2 are loaded in the core of the EHD-printed microfibrous scaffolds in a layer-specific manner. Correspondingly, the tri-layered microfibrous scaffolds have a core–shell fiber size of (25.7 ± 5.1) μm, with a pore size sequentially increasing from (81.5 ± 4.6) μm to (173.3 ± 6.9) μm, and to (388.9 ± 6.9 μm) for the tenogenic, chondrogenic, and osteogenic instructive layers. A rapid release of embedded GFs is observed within the first 2 d, followed by a faster release of SDF-1 and a slightly slower release of differentiation GFs for approximately four weeks. The coaxial EHD-printed microfibrous scaffolds significantly promote stem cell recruitment and direct their differentiation toward tenocyte, chondrocyte, and osteocyte phenotypes in vitro. When implanted in vivo, the tri-layered core–shell microfibrous scaffolds rapidly restored the biomechanical functions and promoted enthesis tissue regeneration with native-like bone-to-tendon gradients. Our findings suggest that the microfibrous scaffolds with layer-specific GFs release may offer a promising clinical solution for enthesis regeneration.

3D printing stands at the forefront of transforming space exploration, offering unprecedented on-demand and rapid manufacturing capabilities. It adeptly addresses challenges such as mass reduction, intricate component fabrication, and resource constraints. Despite the obstacles posed by microgravity and extreme environments, continual advancements underscore the pivotal role of 3D printing in aerospace science. Beyond its primary function of producing space structures, 3D printing contributes significantly to progress in electronics, biomedicine, and resource optimization. This perspective delves into the technological advantages, environmental challenges, development status, and opportunities of 3D printing in space. Envisioning its crucial impact, we anticipate that 3D printing will unlock innovative solutions, reshape manufacturing practices, and foster self-sufficiency in future space endeavors.

Scientists and engineers are looking forward to new manufacturing technologies to realize the integrated fabrication of macro shape and microstructure for the components with a short production chain, which can also save materials and reduce energy consumption. Additive manufacturing (AM) technology is a new fabrication pattern with a character of a lay-by-lay material deposition. The components are fabricated in a bottom-up way, from points, lines, to layers and volume, which provided a capability to solve the impossible integrated fabrication problem for micro- and macro-structure by using conventional manufacturing technologies. Thus, based on integrated fabrication of micro- and macro- structures, research team in Xi'an Jiaotong University has been focusing on technological innovations and applications of advanced additive manufacturing technologies. Novel additive manufacturing principles have been proposed and explored, by which new AM processes and equipment for metals, composites, ceramics, and biomaterials have been developed to support the industrial applications. Additive manufacturing and cutting-edge applications of advanced composite structure, metamaterials, bio-implants, and monocrystal alloy components have been investigated to push the new development of integrated fabrication of micro- and macro- structures.

Three-dimensional (3D) printing provides a promising way to fabricate biodegradable scaffolds with designer architectures for the regeneration of various tissues. However, the existing 3D-printed scaffolds commonly suffer from weak cell-scaffold interactions and insufficient cell organizations due to the limited resolution of the 3D-printed features. Here, composite scaffolds with mechanically-robust frameworks and aligned nanofibrous architectures are presented and hybrid manufactured by combining techniques of 3D printing, electrospinning, and unidirectional freeze-casting. It was found that the composite scaffolds provided volume-stable environments and enabled directed cellular infiltration for tissue regeneration. In particular, the nanofibrous architectures with aligned micropores served as artificial extracellular matrix materials and improved the attachment, proliferation, and infiltration of cells. The proposed scaffolds can also support the adipogenic maturation of adipose-derived stem cells (ADSCs) in vitro. Moreover, the composite scaffolds were found to guide directed tissue infiltration and promote nearby neovascularization when implanted into a subcutaneous model of rats, and the addition of ADSCs further enhanced their adipogenic potential. The presented hybrid manufacturing strategy might provide a promising way to produce additional topological cues within 3D-printed scaffolds for better tissue regeneration.

Additive manufacturing (AM) is considered the most promising technique to realize the in-situ fabrication of complex functional structures in space environments owing to its unique capability of full automation and digitalization. However, unlike printing on the earth, the zero/micro-gravity environment in space makes it extremely challenging to achieve precise deposition and stacking of the printed materials for microscale structures. Here, we proposed to use high-voltage electrostatic force in the electrohydrodynamic printing (EHDP) process as the guiding force for the upward or anti-gravity (AG) printing of microscale functional structures, which can be potentially used for in-space environments. The average electrical field strength for stable AG-EHDP is found in the range of 1.70 × 107V m−1to 2.45 × 107V m−1. In comparison with conventional EHDP, AG-EHDP can fabricate microscale 3D lattice structures with a smaller feature size of 3.65 ± 1.31 µm. A finite element analysis approach is established to simulate the AG-EHDP process at different parameters for the prediction of fiber width, which shows great consistency to the experimental results and applies to zero/micro-gravity printing environments. AG-EHDP also realizes the upward printing of silver microscale structures with a resistance of 7.72 ± 0.83 Ω cm−1, which exhibits the excellent electrothermal capability to heat the cold template from 25 °C to 180 °C within 3 min under an applied voltage of 3 V. It is foreseen that EHDP might provide a promising strategy to fabricate microscale functional structures in zero/micro-gravity space environments.

Reliable insulation of microscale conductive features is required to fabricate functional multilayer circuits or flexible electronics for providing specific physical/chemical/electrical protection. However, the existing strategies commonly rely on manual assembling processes or multiple microfabrication processes, which is time-consuming and a great challenge for the fabrication of flexible transparent electronics with microscale features and ultrathin thickness. Here, we present a novel coaxial electrohydrodynamic (CEHD) printing strategy for the one-step fabrication of microscale flexible electronics with conductive materials at the core and insulating material at the outer layer. A finite element analysis (FEA) method is established to simulate the CEHD printing process. The extrusion sequence of the conductive and insulating materials during the CEHD printing process shows little effect on the morphology of the core–shell filaments, which can be achieved on different flexible substrates with a minimum conductive line width of 32 ± 3.2 μm, a total thickness of 53.6 ± 4.8 μm, and a conductivity of 0.23 × 107S/m. The thin insulating layer can provide the inner conductive filament enough protection in 3D, which endows the resultant microscale core–shell electronics with good electrical stability when working in different chemical solvent solutions or under large deformation conditions. Moreover, the presented CEHD printing strategy offers a unique capability to sequentially fabricate an insulating layer, core–shell conductive pattern, and exposed electrodes by simply controlling the material extrusion sequence. The resultant large-area transparent electronics with two-layer core–shell patterns exhibit a high transmittance of 98% and excellent electrothermal performance. The CEHD-printed flexible microelectrode array is successfully used to record the electrical signals of beating mouse hearts. It can also be used to fabricate large-area flexible capacitive sensors to accurately measure the periodical pressure force. We envision that the present CEHD printing strategy can provide a promising tool to fabricate complex three-dimensional electronics with microscale resolution, high flexibility, and multiple functionalities.

Micro and nanoscale 3D printing has been broadly employed for the manufacturing of biomimetic architectures in the fields of tissue regeneration, personalized medicine, and smart biodevices. The emerging intelligent biomaterials significantly expand the diversity and functionality of printed structures. In this review, the commonly used micro and nanoscale 3D printing techniques were briefly introduced. Recent innovations on intelligent biomaterials like biopolymers, hydrogels, and metallic/ceramic biomaterials were reviewed. The current limitations and future opportunities of 3D-printed intelligent biomaterials for biomedical applications were highlighted. Overall, this review will help the new researchers to understand the underlying principles, functional properties, and potential applications of intelligent biomaterials in micro and nanoscale 3D printing field.

To reveal the complexities of microstructures at the Al/Ti interface, Al/Ti/Al sandwich structures are produced through thermal pressing and annealing treatment. The multi-scale interface structures, elemental diffusion, grain characteristics, and micromechanics are explored by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD), transmission electron microscopy (TEM), and nano-indentation. The results indicate only TiAl3is generated at the interface, and the interlayer thickness and TiAl3grain size increase with rising temperature. On the microscale, a compact interlayer is visible at 500 and 550 °C, whereas massive Al-enriched bulks are dispersed in the interlayer as the temperature increases to 650 °C. Abnormal micro-defects at 600 and 650 °C are partially formed with the thickening of the interlayer and the segregation of Mg and Si. Unexpectedly, interfacial microvoids, amorphous layers, and oxides are detected, which hinder the growth of the interlayer. On the nanoscale, misfit dislocations and lattice distortions are noticed at the interface. More interestingly, the Ti–Al solid solution structures with severe lattice misfits are generated on the three-dimensional (3D) Ti/TiAl3interface, which is considered to be a novel strategy for enhancing the strength-plasticity synergy of composite structures.