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Background: Reconstructing bone structures and stabilizing adjacent joints are clinical challenges in treating talar necrosis and collapse (TNC). 3D printing technology has been demonstrated to improve the accuracy of talar replacement. This study aimed to evaluate anatomical talar replacement and the clinical results. Methods: Nine patients with TNC were enrolled between 2016 and 2020. The prosthetic shape and size were designed by CT post-processing and mirror symmetry technology. The clinical outcomes included radiographic parameters of the forefoot, hindfoot, and ankle alignment, ankle activity, recurrent pain, and peri-operative complications. Results: After a mean follow-up of 23.17 ± 6.65 months, degenerative arthritis and prosthetic dislocation and other complications were not observed on plain radiographs. Each 3D-printed talar prosthesis was placed in the original anatomical position. The parameters which have significant changes pre-operative and post-operative are as follows: talar height, 27.59 ± 5.99 mm and 34.56 ± 3.54 mm (95% CI − 13.05 to − 0.87, t = 2.94, P = 0.032) and Meary's angle, 11.73 ± 4.79° and 4.45 ± 1.82° (95% CI 1.29~22.44, t = 2.89, P = 0.034). The AOFAS hindfoot score improved from 26.33 ± 6.62 to 79.67 ± 3.14 at the final follow-up (95% CI 43.36~63.30, t = 13.75, P = 0.000). The VAS score decreased from 6.33 ± 1.03 to 0.83 ± 0.75 (95% CI 4.40~6.60, t = 12.84, P = 0.000). The post-operative satisfaction scores regarding pain relief, activities of daily living, and return to recreational activities were good to excellent, and the change of activity range was statistically significant. Conclusions: The 3D printing patient-specific total talar prostheses allowed anatomical reconstruction in TNC. This novel treatment with 3D-printed prostheses could serve as a reliable patient-specific alternative in TNC. [ABSTRACT FROM AUTHOR]

Micro-supercapacitors (MSCs) with excellent electrochemical behaviours and flexibility possess great promise for portable and wearable electronic devices. A novel type of hybrid-dimensional Fe2O3/graphene/Ag ink is developed and extruded into MSC electrodes through the direct ink writing-based three-dimensional (3D) printing. The optimal solid-state MSC device exhibits a maximum areal capacitance of 412.3 mF cm−2 at 2 mA cm−2, a correspondingly high energy density of 65.4 μWh cm−2 and 89% capacitance retention for over 5000 charge and discharge cycles. The superior electrochemical performance is profited by the high electron transport synergistically boosted by two-dimensional graphene nanosheets and one-dimensional Ag nanowires, and the high pseudocapacitive behaviours of Fe2O3 nanoparticles. The 3D printed MSC exhibits reliable flexibility with remarkable retention of 90.2% of its original capacitance after 500 bending cycles. The current 3D printing fabrication demonstrates an efficient route for advanced miniaturised electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Micro-pseudocapacitors (MPCs) are prospective power source candidates with compatible sizes as well as superior power densities for miniaturized electronic devices; however, their limited capacitive charge storage characteristics are still hindering their further development. Herein, an optimized 3D printing technique is employed to build remarkable reduced holey graphene oxide (rHGO) supported MPC microelectrodes. In such microelectrodes, the presence of macroscale pores introduced through freeze drying is beneficial to the accessibility to electrolyte ions. Moreover, with two additional pore modals including the microscale pores from pseudocapacitive nanoparticles stacking and nanoscale in-plane holes formed by rational HGO engineering, the MPC microelectrodes offer an enhancement in both electrical and ionic transports. The resultant 3D-printed planar MPCs exhibit a remarkable device specific charge storage capacity of 241.3 mC cm−2, which is approximately 1.7-fold that of a non-optimized one and much higher than most reported planar micro-supercapacitors. Superior rate capability and high capacity retention (91% capacity retention after 11000 charge and discharge cycles) are also achieved. Our porosity engineering strategy combined with 3D printing is expected to serve as a facile and general design in the roadmap for next-generation state-of-the-art customized electrochemical energy storage devices. Image 1 [ABSTRACT FROM AUTHOR]

Stage IIIc Kienböck's disease is a clinical challenge to treat collapse of the lunate bone. A new reconstructive surgery was described in one patient using 3D printing lunate prosthesis. The prosthesis shape was designed by tomographic image processing and segmentation using technology compared with the intact side matched by mirror symmetry and 3D post-processing technologies. The patient recovered nearly full range of motion of the wrist after 12 months. The visual analog scale scores and Cooney scores were 2 points and 91 points. We demonstrated that an anatomical reconstruction to Kienböck's Disease is possible using 3D printing lunate prosthesis. [ABSTRACT FROM AUTHOR]

Micro-sized electrochemical energy storage device is a prospective candidate to power the miniaturized electronic devices and micro-pseudocapacitor (MPC) is a typical one with high power density and long life span. Developing a versatile architectural design with high capacity delivering in a micrometer range is paramount for remarkable MPC constructions. Here, an interdigitated graphene framework (IGF) is developed using a facile 3D printing technique to enable the customized geometries as well as the superior support of metal oxide nanostructures. With this unique design, the IGF-supported NiO nanorod heterostructured microelectrodes deliver high specific capacity of 220.2 C g−1 (400.3 F g−1). When directly assembled to quasi-solid-state symmetric MPCs, the NiO filled one exhibits a remarkable device capacity of 197.5 mC cm−2. Robust MPC cycling stabilities are also demonstrated during 10000 charge and discharge cycles. In addition to the NiO based ones, MnO 2 nanosheet filled MPCs are also fabricated, where a high device capacity and a good cycling stability are also exhibited. We expect that this novel 3D-printed IGF can pave the way for constructing state-of-the-art miniaturized electrochemical energy storage devices with customized geometries. Image 1 [ABSTRACT FROM AUTHOR]

Due to the high manufacturing cost of titanium compressor blisks, aero engine repairing process research has important engineering significance and economic value. TC17 titanium alloy is a rich β stable element dual α+β phase alloy whose nominal composition is Ti-5Al-2Sn-2Zr-4Mo-4Cr. It has high mechanical strength, good fracture toughness, high hardenability and a wide forging-temperature range. Through a surface response experiment with different laser powers, scanning speeds and powder feeding speeds, the coaxial powder feeding laser melting deposition repair process is studied for the surface circular groove defects. In this paper, the tensile properties, relative density, microhardness, elemental composition, internal defects and microstructure of the laser-repaired TC17 forging plate are analyzed. The results show that the laser melting deposition process could realize the form restoration of groove defect; tensile strength and elongation could reach 1100 MPa and 10%, which could reach 91–98% that of original TC17 wrought material; with the optimal parameters (1000 W-25 V-8 mm/s), the microhardness of the additive zone, the heat-affected zone and base material is evenly distributed at 370–390 HV500. The element content difference between the additive zone and base material is less than ±0.15%. Due to the existence of the pores 10 µm in diameter, the relative density could reach 99%, which is mainly inversely proportional to the powder feeding speed. The repaired zone is typically columnar and dendrite crystal, and the 0.5–1.5 mm-deep heat-affected zone in the groove interface is coarse equiaxial crystal. [ABSTRACT FROM AUTHOR]