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Bone scaffolds require both good bioactivity and mechanical properties to keep shape and promote bone repair. In this work, T-ZnOw enhanced biphasic calcium phosphate (BCP) scaffolds with triply periodic minimal surface (TPMS)-based double-layer porous structure were fabricated by digital light processing (DLP) with high precision. Property of suspension was first discussed to obtain better printing quality. After sintering, T-ZnOw reacts with β-tricalcium phosphate (β-TCP) to form Ca19Zn2(PO4)14, and inhibits the phase transition to α-TCP. With the content of T-ZnOw increasing from 0 to 2 wt%, the flexural strength increases from 40.9 to 68.5 MPa because the four-needle whiskers can disperse stress, and have the effect of pulling out as well as fracture toughening. However, excessive whiskers will reduce the cure depth, and cause more printing defects, thus reducing the mechanical strength. Besides, T-ZnOw accelerates the deposition of apatite, and the sample with 2 wt% T-ZnOw shows the fastest mineralization rate. The good biocompatibility has been proved by cell proliferation test. Results confirmed that doping T-ZnOw can improve the mechanical strength of BCP scaffolds, and keep good biological property, which provides a new strategy for better bone repair.

In recent years, amorphous bioglass is used to improve the bioactivity of HA (Ca10(PO4)6(OH)2). Nevertheless, bioglass crystallizes and reacts with the matrix to form a complex phase composition during sintering, resulting in an unclear mechanism for tailoring the properties of HA bioceramics. In this work, TPMS structural HA ceramics fabricated by digital light processing (DLP) were doped by akermanite (Ca2MgSi2O7) to better tailor the porosity, bioactivity and mechanical strength. After sintering above 1000 °C, Mg2+ ions from akermanite substitute Ca2+ ions in HA, leading to the decomposition of HA into β-TCP. This process increases the porosity of bioceramics. Additionally, liquid phases sintering caused by akermanite gives rise to the densification and enhancement of grain bonding, thereby reinforcing the mechanical strength of scaffolds. For in vitro bioactivity, as the content of akermanite increases from 0 wt.% to 20 wt.%, carbonated hydroxyapatite firstly deposits onto the surfaces of scaffolds and then disappears, because excessive Mg2+ prevent the hydroxyapatite crystallization. Finally, bioceramics with 5 wt.% and 10 wt.% of akermanite and sintering at 1100 °C exhibit a high porosity of over 80% and an appropriate compressive strength of over 2 MPa, while achieving an enhanced in vitro bioactivity and good biocompatibility. After optimization, this kind of porous scaffolds can be well applied to the repair of cancellous bone defect.

It is difficult to prepare ceramic cores by traditional technology due to high dependence on mold and the difficulty of manufacturing complex structures. Additive manufacturing technology can solve these problems. In this study, the silica ceramics were prepared by selective laser sintering (SLS) based on particle grading. Adding appropriate amount of fine powder to coarse powder could improve the mechanical properties of silica ceramics. As a result, the flexural strength of silica green bodies reached a maximum of 3.20 MPa when the mass ratio of coarse powder (D50 = 45.6 μm) and fine powder (D50 = 23.3 μm) was 4:5. With the increase of fine powder content, the shrinkage and flexural strength of silica ceramics first increased and then decreased, while the apparent porosity showed an opposite trend. When the mass ratio was 4:5, the maximum of flexural strength was 7.15 MPa with the linear shrinkage of 4.76% and the apparent porosity of 47.28%. Compared with silica ceramics without fine powder, the flexural strength of silica ceramics increased by nearly 550% (from 1.13 MPa to 7.15 MPa) under the optimal particle grading. Therefore, the silica ceramics with good mechanical properties were prepared by SLS via optimizing the particle grading.

Gas-in-liquid foam templating is considered as a promising method for commercial-scale production of porous materials. However, Ostwald ripening occurs frequently during the preparation, which could bring about inhomogeneous bubbles with large sizes and deteriorate the performance of resultant products. To tackle this challenging task, we report a gelation network-triggered morphology-regulation strategy during the foaming process. As an exemplar, boehmite sol was incorporated into the andalusite suspension to stabilize the foam framework. After casting, the wet foam was able to maintain its overall shape, since andalusite particles were anchored onto the gas-liquid interface by the gelation network during mechanical frothing. The samples calcined at 1400°C feature homogeneous bubble with hierarchical porous architecture, smaller pore size with a mean value of 5.32 μm and robust compressive strength of 11.97MPa at a porosity level of 84 %. Our approach substantially broadens the design philosophy of high performance porous ceramics.

Purpose: The research aimed to verify the applicability of low computational complexity and high diagnosis accuracy deep convolutional neural network, using MobileNetV2 to identify the presence of chest catheters and tubes on chest X-ray images. Methods: The dataset of chest X-rays collected from a teaching hospital included the endotracheal tube (ETT), the central venous catheter (CVC), and the nasogastric tube (NGT) datasets. A new method of applying dynamic image size training procedures was implemented and compared with fixed image size training. The idea is to learn more features through dynamic image size training. Transfer learning with pre-trained MobileNetV2 on ImageNet was conducted to accelerate the training process and acquire higher accuracy. Class activation mapping (CAM) was also employed to visualize artificial intelligence (AI) predictions, making AI decisions more explainable. Results: The ETT datasets included 10464 X-ray images, while the CVC and NGT datasets contained 10274 and 9610 images, respectively. The accuracies for ETT, CVC, and NGT are 99.0%, 98.4%, and 96.2% in the validation dataset, while in the testing dataset are 98.8%, 98.6%, and 96.8%, respectively. The area under the receiver operating characteristics (AUROCs) were 0.992, 0.988, and 0.980 in the ETT, CVC, and NGT testing datasets. Conclusion: MobileNetV2 with the dynamic image size achieved dedicated performance in the application of chest catheters and tubes classifications. The similarity of the accuracy between the validation and testing data suggests the good generalization capability of the model.

Silica ceramic cores have played an important part in the manufacture of hollow blades due to their excellent chemical stability and moderate high-temperature mechanical properties. In this study, silica-based ceramics were prepared with Al2O3 addition by stereolithography, and the influence of Al2O3 content on mechanical properties of the silica-based ceramics was investigated. The Al2O3 in silica-based ceramics can improve the mechanical properties by playing a role as a seed for the crystallization of fused silica into cristobalite. As a result, with the increase of Al2O3 content, the linear shrinkage of the silica-based ceramics first decreased and then increased, while the room-temperature flexural strength and the high-temperature flexural strength first increased and then decreased. As the Al2O3 content increased to 1.0 vol%, the linear shrinkage was reduced to 1.64% because of the blocked viscous flow caused by Al2O3. Meanwhile, the room-temperature flexural strength and the high-temperature flexural strength were improved to 20.38 and 21.43 MPa with 1.0 vol% Al2O3, respectively, due to the increased α-cristobalite and β-cristobalite content. Therefore, using the optimal content of Al2O3 in silica-based ceramics can provide excellent mechanical properties, which are suitable for the application of ceramic cores in the manufacturing of hollow blades.

Exploring high-safety but convenient encryption and decryption technologies to combat threats of information leakage is urgently needed but remains a great challenge. Here, a synergistically time- and temperature-resolved information coding/decoding solution based on functional photonic inks is demonstrated. Encrypted messages can be stored into multiple channels with dynamic-color patterns, and information decryption is only enabled at appointed temperature and time points. Notably, the ink can be easily processed into quick-response codes and multipixel plates. With high transparency and responsive color variations controlled by ink compositions and ambient temperatures, advanced 3D stacking multichannel coding and Morse coding techniques can be applied for multi-information storage, complex anticounterfeiting, and information interference. This study paves an avenue for the design and development of dynamic photonic inks and complex encryption technologies for high-end anticounterfeiting applications.

Recent reports on the selective laser melting (SLM) process under a vacuum or low ambient pressure have shown fewer defects and better surface quality of the as-printed products. Although the physical process of SLM in a vacuum has been investigated by high-speed imaging, the underlying mechanisms governing the heat transfer and molten flow are still not well understood. Herein, we first developed a mesoscopic model of SLM under variable ambient pressure based on our recent laser-welding studies. We simulated the transport phenomena of SLM 316L stainless steel powders under atmospheric and 100 Pa ambient pressure. For typical process parameters (laser power: 200 W; scanning speed: 2 m∙s−1; powder diameter: 27 μm), the average surface temperature of the cavity approached 2800 K under atmospheric pressure, while it came close to 2300 K under 100 Pa pressure. More vigorous fluid flow (average speed: 4 m∙s−1) was observed under 100 Pa ambient pressure, because the pressure difference between the evaporation-induced surface pressure and the ambient pressure was relatively larger and drives the flow under lower pressure. It was also shown that there are periodical ripple flows (period: 14 μs) affecting the surface roughness of the as-printed track. Moreover, the molten flow was shown to be laminar because the Reynolds number is less than 400 and is far below the critical value of turbulence; thus, the viscous dissipation is significant. It was demonstrated that under a vacuum or lower ambient pressure, the ripple flow can be dissipated more easily by the viscous effect because the trajectory length of the ripple is longer; thus, the surface quality of the tracks is improved. To summarize, our model elucidates the physical mechanisms of the interesting transport phenomena that have been observed in independent experimental studies of the SLM process under variable ambient pressure, which could be a powerful tool for optimizing the SLM process in the future.

Additive manufacturing is expected to transform and upgrade the traditional foundry industry to realize the integrated manufacturing and rapid and low-cost development of high-performance components with complex shapes. The additive manufacturing technology commonly applied in casting mold preparation (fusible molds, sand molds/cores and ceramic cores) mainly includes selective laser sintering (SLS) and binder injection three-dimensional printing (3DP). In this work, the research status of SLS/3DP-casting processes on material preparation, equipment development, process optimization, simulation and application cases in aerospace, automotive and other fields were elaborated. Finally, the developing trends of the additive manufacturing technology in the future of foundry field are introduced, including multi-material sand molds (metal core included), ceramic core-shell integration and die-casting dies with conformal cooling runners.

Porous Al2O3-based ceramics with improved mechanical strength and different pore size were fabricated using Al2O3 and SiO2 poly-hollow microspheres (PHMs) as raw materials by selective laser sintering (SLS). The effects of different contents of SiO2 PHMs on phase compositions, microstructures, mechanical properties and pore size distribution of the prepared ceramics were investigated. It is found that moderate content of SiO2 PHMs (≤30 wt%) could work as a sintering additive, which could enhance the bonding necks between Al2O3 PHMs. When the content of SiO2 PHMs increased from 0 wt% to 30 wt%, the compressive strength of Al2O3-based ceramics increased from 0.3 MPa to 4.0 MPa, and the porosity decreased from 77.0% to 65.0% with open pore size decreased from 52.0 μm to 38.3 μm. However, SiO2 PHMs could provide pores by keeping its integrity when the content of SiO2 PHMs increased to 40 wt%, which could result in the porosity increasing to 66.8% and pore size decreasing to 30.1 μm. Selective laser sintering of different kinds of ceramic PHMs is a feasible method to fabricate porous ceramics with complex shape, controllable pore size and improved properties.

For nanofibrous aerogels, a three-dimensional porous structure with interwoven nanofibers as a pore wall has become an urgent demand, and it remains to be a challenge to ensure the mechanical stability and thermal insulation. Other than the reported nanofiber as raw materials to generate three-dimensional cellular nanofibrous aerogels, an alternative low-cost and facile procedure has been proposed here via tactfully utilizing polymer sponge as a template attached with reactive particles, followed by a carbothermal reduction process to realize nanowire growth and their replacement of the original framework. The resulting spongy aerogels with numerous interlaced SiC/Si3N4 nanowires as a skeleton exhibit an ultrahigh porosity of 99.79%. Meanwhile, compressive elasticity after a compression at strain of 35% for 400 cycles, a low thermal conductivity of 23.19 mW/(m K), an excellent absorption capacity of 33.9-95.3 times for varied organic solvents removal, along with flexibility in shape design favored by the initial organic sponge make this nanofibrous aerogel an ideal material for heat shielding, absorption, or catalyst support.

Ultra-low magnetic field systems have attracted increasing attention in recent years because they lack cryocoolers and exhibit lightweight, low cost, and mobilization convenience. In contrast to permanent magnet systems, electromagnetic systems can easily vary background magnetic fields, thus offering opportunities on multiple scales of time and distance to characterize the molecular dynamics and transport properties of complex liquids in bulk or embedded in confined environments. An unconventional ultra-low field bell-shaped head MRI magnet with a dedicated compact structure is needed for applications in clinics, intensive care units, and mobile vans and evaluating stroke in the hyperacute and acute stages. In this work, we use the discrete minimum energy (DME) method to design the ultra-low field bell-shaped head MRI electromagnet. This method involves obtaining a DME current map, initial coil extraction, and coil adjustment. The DME map is used to determine the initial current distribution of the MRI electromagnet over a predefined domain subject to constraints. Then, initial coil extraction aims to extract the initial regularized rectangle coil layout from the DME map. Considering that the extraction process decreases magnetic field homogeneity in the region of interest (ROI), coil adjustment is then implemented. This step adjusts the position and volume of the initial coil layout to meet the homogeneity requirement. A bell-shaped electromagnet ( $$< 20$$ mT, 2 MA/m $$^2$$ ) with a homogeneity of 7 ppm over 260 mm DSV is designed in this work.

Solid polymer electrolytes with relatively low ionic conductivity at room temperature and poor mechanical strength greatly restrict their practical applications. Herein, we design semi-interpenetrating network polymer (SNP) electrolyte composed of an ultraviolet-crosslinked polymer network (ethoxylated trimethylolpropane triacrylate), linear polymer chains (polyvinylidene fluoride-co-hexafluoropropylene) and lithium salt solution to satisfy the demand of high ionic conductivity, good mechanical flexibility, and electrochemical stability for lithium metal batteries. The semi-interpenetrating network has a pivotal effect in improving chain relaxation, facilitating the local segmental motion of polymer chains and reducing the polymer crystallinity. Thanks to these advantages, the SNP electrolyte shows a high ionic conductivity (1.12 mS cm-1 at 30 °C), wide electrochemical stability window (4.6 V vs. Li+ /Li), good bendability and shape versatility. The promoted ion transport combined with suppressed impedance growth during cycling contribute to good cell performance. The assembled quasi-solid-state lithium metal batteries (LiFePO4 /SNP/Li) exhibit good cycling stability and rate capability at room temperature.

Perovskite Ba0.67Sr0.33TiO3 (BST) ceramics with improved dielectric performance were fabricated by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method using 0.5 mol% MgO as the coagulation agent. The influence of sintering temperature on micromorphology, crystal structure, and dielectric performance of BST ceramic components was systematically evaluated. The densification rate of BST samples could reach the maximum at a heating temperature around 1305 °C and end up approximately at 1380 °C. As increasing the sintering temperature from 1400 to 1550 °C, the relative density of BST ceramics decreases from 98.82 ± 0.16% to 96.72 ± 0.06%, and the mean grain size drops gradually from 9.96 to 4.68 μm. The increased sintering temperature promotes the lattice expansion due to Ti4+ replacement at B site by Mg2+, as well as the generation of oxygen vacancies. In addition, as increasing sintering temperature, the dielectric permittivity (er) of BST ceramic components decreases first and then slightly increases, while the dielectric loss (tanδ) of ceramics shows the opposite trend. The results indicate that the initial tanδ increase is mainly attributed to the lattice expansion of BST ceramics, and the subsequent loss reduction results from the easily localized conduction electrons on Mg2+ sites reducing the carrier concentration. The samples sintered at 1550 °C show the lowest dielectric loss (tanδ≈0.013), which is significantly reduced by an order of magnitude compared with that of dry-pressed samples (tanδ≈0.262).

Dielectric energy storage materials and capacitors are one of the key components for power electronics. Although strenuous efforts have been made to explore high-performance energy storage materials, the trade-off between the high polarization and high breakdown strength limits the energy density of the materials. In this work, a composition engineering strategy has been proposed to overcome the trade-off between the polarization and the breakdown strength. We introduced (Sr1.05Bi0.3)ScO3 (SBS) into 0.85Bi0.5Na0.5TiO3–0.15NaNbO3 (BNT–NN), where the Sc2O3 embedded in the grains constructs insulating networks to enhance the breakdown strength, while the Sc3+ and Sr2+ ions enter the BNT–NN lattices and smash the R3c domains into ferroelectric polar nanoregions, maintaining the high polarization and decreasing the remnant polarization. As a result, 0.3 SBS doped BNT–NN shows a recoverable energy density (Wrec) of 7.3 J cm−3, one of the highest values for lead-free ferroelectric ceramics with a desirable energy efficiency (η) of 80%. Combined with its favorable temperature and frequency stabilities and discharge ability, the SBS doped 0.85Bi0.5Na0.5TiO3–0.15NaNbO3 could be a promising material for practical energy storage applications.

The mechanical properties of porous ceramics prepared by poly-hollow microspheres (PHMs) is usually low because of the weak bonding between different ceramic PHMs. In this paper, CaSiO3 were coated to the surface of Al2O3 PHMs through co-precipitation method as sintering additive to improve the properties of Al2O3 poly-hollow microsphere ceramics (Al2O3 PHM ceramics). The influence of different amount of CaCl2 solution on properties of the Al2O3 PHM ceramics such as phase composition, microstructure, porosity and mechanical properties were studied. The porosity of the Al2O3 PHM ceramics decreased from 77.03% to 68.16% with the increase of CaCl2 solution amount, while compressive strength increased 29 times from 0.29 MPa to 8.39 MPa. The addition of the CaSiO3 could decrease the sintering temperature of Al2O3 PHM ceramics and significantly improve the mechanical properties of Al2O3 PHM ceramics, which is beneficial for preparing highly porous Al2O3 PHM ceramics with high mechanical properties and complex shapes.

Indirect selective laser sintering (SLS) was combined with reactive melt infiltration (RMI) to fabricate RB-SiC, and the effects of preform impregnation with different carbon source on the carbonized sample and final RB-SiC were investigated. Results show that the impregnation treatment led to increased bulk density and mechanical strength of samples at all stages. The pore size dwindled and the porosity decreased significantly for the carbonized sample, and the content of Si reduced for the final RB-SiC. The impregnation with PF resin containing 30 % nano carbon black (PFnanoC) seems more promising for the comprehensive properties improvement, the final RB-SiC had a relatively fewer amount of residual pore and carbon and showed superior mechanical properties compared with those of sample impregnated with only PF resin. Kinetics analysis indicates a slower pore-clogging rate under the PFnanoC impregnation condition, which avoided or hindered a too-early infiltration cease during the RMI process.

Novel form of SiC–Si3N4 composite has been prepared via a simple and versatile route, namely carbon-doped sol with aligned pores from freeze casting method in combination with the subsequent carbothermal reduction process. The oriented pores of green bodies supply both nitrogen and space for the nucleation and growth of Si3N4 nanowires following the VS mechanism. Meanwhile, lack of nitrogen at partial region leads to the generation of aggregated β-SiC particulates. As a result, multiply laminate nanofibrous ceramic foams embedded with fine particles have been prepared. Owing to the low bulk density of 0.15 g/cm3 and fine building blocks, this novel material possesses relatively high specific surface area of 29.89 m2/g and ultra-low thermal insulation of 0.058 W/(m·K), which would have potential applications in the catalysts, thermal insulators or gas/liquid filters fields.

Porous mullite ceramics with a fully closed-cell structure were fabricated by direct coagulation casting (DCC) using fly ash hollow spheres (FAHSs) as the non-sacrificial pore-forming agent. Kaolin powder was used as the filler and the suspension stabilizer, and bentonite was used as the rheological additive, respectively. The effects of bentonite on the stabilization mechanism of suspension and properties of the porous ceramics were investigated. It is found that 1 wt% additional bentonite is efficient in improving the suspension stability from 2 h to at least 24 h, due to increased suspension viscosity, thixotropy and yield stress. Densification of the kaolin powder during sintering eliminates the open pores, and the closed pores from FAHSs remain to yield a fully closed-cell structure. The porous mullite ceramics have a total porosity ranging from 44.73% to 46.12%, in which 99% of the pores are closed. Bentonite also increases the compressive strength of porous mullite ceramics by 14.4%, and compressive strength of 58.07 ± 5.44 MPa can be achieved.

Ba0.67Sr0.33TiO3 (BST) ceramics with highly improved dielectric performance were fabricated by a novel direct coagulation casting via high valence counter ions (DCC-HVCI) method. The influence of solid loading on densification behavior, micromorphology, and dielectric performance of the samples was investigated. With the increase of solid loading from 40 to 50 vol%, the maximum densification rate of BST ceramics increased from 0.090 to 0.122 s−1, and the densification temperature decreased from 1424 to 1343 °C, which indicated that high solid loading could promote the densification behavior of samples during sintering. BST ceramics fabricated by the DCC-HVCI method showed uniform grain size and microstructure, which was beneficial for the dielectric properties of BST ceramics. Samples obtained from 45 vol% suspensions possessed the lowest dielectric permittivity (er ≈ 2801), and the dielectric loss (tanδ≈0.0262) was about 1/10 of that of dry-pressed samples (tanδ≈0.301), which could be attributed to the composition homogenization.