Cell Development Enhanced Bionic Silk Hydrogel on Remodeling Immune Pathogenesis of Spinal Cord Injury via M2 Polarization of Microglial

Due to the complex spatial-temporal pathophysiology of spinal cord injury (SCI), effective modulation of SCI-specific inflammatory pathogenesis to achieve desirable therapeutic effects on functional recovery still remains challenging. Herein, cell-enhanced photocrosslinked silk fibroin hydrogels with extracellular matrix-mimicking cues of mechanical properties and RGD (Arg-Gly-Asp) signals are gelled in situ to fill the lesion site to modulate injury-induced neuroinflammation and promote neurite regrowth after SCI. The bionic hydrogel system provides biomimetic mechanical cues to promote neuronal differentiation of neural stem/progenitor cells (NPCs) and neurite growth by activating YAP nuclear expression. Importantly, favored by the strong capacity of silk fibroin hydrogels on macrophage/microglia recruitment, NPCs encapsulated hydrogel (NPCs@SFRGD0.1) effectively promotes recruited macrophages/microglia to M2 polarization in the lesion site by releasing S100A4 and thereby remodels the inflammatory microenvironment after SCI. Moreover, NPCs@SFRGD0.1 successfully reduces glial scar formation and accelerates corticospinal tract axon regrowth to improve locomotor recovery. Overall, this work contributes to illustrating the therapeutic mechanism of NPCs development based biomaterial therapies on modulating inflammatory microenvironment and this NPCs enhanced silk fibroin hydrogel provides a promising therapeutic strategy for SCI.     

Tough Transient Ionic Junctions Printed with Ionic Microgels

Emerging soft ionotronics better match the human body mechanically and electrically compared to conventional rigid electronics. They hold great potential for human-machine interfaces, wearable and implantable devices, and soft machines. Among various ionotronic devices, ionic junctions play critical roles in rectifying currents as electrical p–n junctions. Existing ionic junctions, however, are limited in electrical and mechanical performance, and are difficult to fabricate and degrade. Herein, the design, fabrication, and characterization of tough transient ionic junctions fabricated via 3D ionic microgel printing is reported. The 3D printing method demonstrates excellent printability and allows one to fabricate ionic junctions of various configurations with high fidelity. By combining ionic microgels, degradable networks, and highly charged biopolymers, the ionic junctions feature high stretchability (stretch limit 27), high fracture energy (>1000 Jm⁻²), excellent electrical performance (current rectification ratio >100), and transient stability (degrade in 1 week). A variety of ionotronic devices, including ionic diodes, ionic bipolar junction transistors, ionic full-wave rectifiers, and ionic touchpads are further demonstrated. This study merges ionotronics, 3D printing, and degradable hydrogels, and will motivate the future development of high-performance transient ionotronics.     

C-Shaped Cartilage Development Using Wharton's Jelly-Derived Hydrogels to Assemble a Highly Biomimetic Neotrachea for use in Circumferential Tracheal Reconstruction

A highly biomimetic neotrachea with C-shaped cartilage rings has promising clinical applications in the treatment of circumferential tracheal defects (CTDs) owing to its structure and physiological function. However, to date, most fabricated tracheal cartilages are O-shaped. In this study, finite element analysis demonstrates C-shaped cartilage rings that exhibit better compliance than O-shaped. Hydrogel is developed using methacryloyl-modified decellularized Wharton's jelly matrix (DWJMA) for the regeneration of C-shaped cartilage rings. This novel hydrogel possesses adjustable physicochemical properties and favorable cytocompatibility. When loaded with chondrocytes, DWJMA hydrogels support the optimal cartilage regeneration both in vitro and in vivo. More importantly, a highly biomimetic neotrachea simultaneously simulating the structural and physiological properties of the normal trachea is regenerated via modular assembly of several individual C-shaped cartilage rings. The results demonstrate the highly biomimetic neotrachea have better patency (88.6 ± 6.1% vs 74.4 ± 9.4%, p < 0.05), improve the survival rate, alleviate weight loss and mucoid impaction, than its O-shaped counterpart when used for the treatment of CTDs in a rabbit model. Therefore, this study proposes a novel hydrogel for the regeneration of C-shaped cartilage and provides new insights into the treatment of CTDs using a highly biomimetic neotrachea with C-shaped cartilage rings.     

Highly Conductive MXene/PEDOT:PSS-Integrated Poly(N-Isopropylacrylamide) Hydrogels for Bioinspired Somatosensory Soft Actuators

Sophisticated sensing and actuation capabilities of many living organisms in nature have inspired scientists to develop biomimetic somatosensory soft robots. Herein, the design and fabrication of homogeneous and highly conductive hydrogels for bioinspired somatosensory soft actuators are reported. The conductive hydrogels are synthesized by in situ copolymerization of conductive surface-functionalized MXene/Poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) ink with thermoresponsive poly(N-isopropylacrylamide) hydrogels. The resulting hydrogels are found to exhibit high conductivity (11.76 S m⁻¹), strain sensitivity (GF of 9.93), broad working strain range (≈560% strain), and high stability after over 300 loading–unloading cycles at 100% strain. Importantly, shape-programmable somatosensory hydrogel actuators with rapid response, light-driven remote control, and self-sensing capability are developed by chemically integrating the conductive hydrogels with a structurally colored polymer. As the proof-of-concept illustration, structurally colored hydrogel actuators are applied for devising light-driven programmable shape-morphing of an artificial octopus, an artificial fish, and a soft gripper that can simultaneously monitor their own motions via real-time resistance variation. This work is expected to offer new insights into the design of advanced somatosensory materials with self-sensing and actuation capabilities, and pave an avenue for the development of soft-matter-based self-regulatory intelligence via built-in feedback control that is of paramount significance for intelligent soft robotics and automated machines.     

Asymptotic switched composite adaptive control with application to robotic interaction tasks

This article proposes a new switched adaptive control design for uncertain switched systems with composite (time-driven and state-dependent) switching and shows its applicability in switched impedance control. A composite switched adaptive control design, consisting of the direct switched adaptive control and the indirect switched adaptive control counterpart, is developed to improve the control performance. Specifically, a new stability condition for composite switching is proposed by making use of differential matrix equations and Sylvester matrix equations, which are a generalization of Lyapunov matrix equations. The design results in a time-varying multiple Lyapunov function that is decreasing at the switching instants. From the theoretical point of view, the relevance of this work is the construction of the adaptive laws that guarantee asymptotic tracking error and asymptotic estimation for the direct and indirect switched adaptive control loops, respectively. From the practical point of view, the relevance of this work is validated in a new switched impedance control for the robot interaction with uncertain and discontinuous environments.     

Fe3Se8/Co3Se4/NiSe2/NC复合材料的制备及性能

由于锂资源的价格逐渐攀升,亟需开发价格低廉的电池系统。通过共沉淀法合成FeCoNiCP片状前驱体,再经过包覆多巴胺、退火和在氮气下硒化,制备钠离子电池负极材料Fe₃Se₈/Co₃Se₄/NiSe₂/NC。在0.01~3.00 V充放电,以0.1 A/g的电流循环70次,电极仍有468.38 mAh/g的可逆比容量;在0.1 A/g、0.2 A/g、0.5 A/g、1.0 A/g、2.0 A/g和5.0 A/g的电流下,分别具有363.85 mAh/g、345.88 mAh/g、320.73 mAh/g、308.31 mAh/g、290.33 mAh/g和249.29 mAh/g的可逆比容量。Fe₃Se₈/Co₃Se₄/NiSe₂/NC复合材料较好的电化学性能,可归因于碳导电网络、多金属硒化物和独特的纳米结构的协同作用,缓解了充放电过程中的体积膨胀。     

电压互感器手车复合绝缘失效及电场分布的研究北大核心CSCD

复合绝缘是空气绝缘开关设备小型化设计的一种重要绝缘方式。复合绝缘结构的PT(电压互感器)柜运行情况表明,该类型产品的绝缘故障率较高,特别是在湿度和污秽联合影响下,因绝缘结构设计不当的产品很容易产生局部放电,进而引发相间短路。究其原因,绝缘隔板是相间短路的"桥梁"。文中对一起24 kV PT手车三相短路事故原因进行了详细分析,通过电场仿真结果可以看出:在复合绝缘结构中,高压对绝缘板之间的距离是复合绝缘结构设计的关键。文中的故障分析以及电场分析为新产品开发与故障诊断提供了有益的参考。     

复合横担杆塔不平衡张力调节装置及其设计方法研究

针对复合横担杆塔易承受较大不平衡张力的问题,设计了一种杆塔不平衡张力自动调节装置,结合装置特点构建了不平衡张力计算方程组,提出了迭代求解方法,分析了装置结构参数对不平衡张力调节效果的影响规律。研究表明不平衡张力调节装置可有效降低在断线或不均匀覆冰工况下挂点处的最大不平衡张力。     

自适应提升及预测误差修正的风电功率超短期预测

为了提高超短期风电功率预测精度,提出了一种自适应提升及预测误差修正的风电功率超短期预测方法。首先,使用CEEMDAN将原始风电功率序列分解为多个分量,用RCMSE对其重构成新模态以降低风电功率序列复杂性及提高预测效率;其次,用EESHHO优化ELM权值和阈值提高模型的泛化性,同时引入AdaBoost提高预测模型的精确度和稳定性;最后,在学习历史训练误差的基础上提出修正预测值的策略,进一步提高预测精度。算例结果验证了所提方法的有效性。     

一种Ku波段综合馈电多功能板的研制

基于多层微波数字复合基板层叠互联技术,研制的Ku波段综合馈电多功能板集成了射频收发网络、电源分配网络、阵面波控及波控分配网络,主要负责16个片式T/R组件的功率分配与合成,同时为各T/R组件提供电源及控制信号。文中对多功能板的架构设计、工作原理进行了说明,重点介绍了各微波垂直互联电路和射频收发网络的设计,最后加工并测试了验证样件,测试结果良好。收发网络总口驻波＜1.9,分口驻波＜1.3,插损＜16 dB,相邻端口的隔离度＞20 dB,且幅度一致性≤0.602 dB,相位一致性≤6.429°。工程应用可行性和实用性得到了验证。