Self-Adhesive Polydimethylsiloxane Foam Materials Decorated with MXene/Cellulose Nanofiber Interconnected Network for Versatile Functionalities

Polydimethylsiloxanes (PDMS) foam as one of next-generation polymer foam materials shows poor surface adhesion and limited functionality, which greatly restricts its potential applications. Fabrication of advanced PDMS foam materials with multiple functionalities remains a critical challenge. In this study, unprecedented self-adhesive PDMS foam materials are reported with worm-like rough structure and reactive groups for fabricating multifunctional PDMS foam nanocomposites decorated with MXene/cellulose nanofiber (MXene/CNF) interconnected network by a facile silicone foaming and dip-coating strategy followed by silane surface modification. Interestingly, such self-adhesive PDMS foam produces strong interfacial adhesion with the hybrid MXene/CNF nano-coatings. Consequently, the optimized PDMS foam nanocomposites have excellent surface super-hydrophobicity (water contact angle of ≈159^o), tunable electrical conductivity (from 10⁻⁸ to 10 S m⁻¹), stable compressive cyclic reliability in both wide-temperature range (from −20 to 200 ^oC) and complex environments (acid, sodium, and alkali conditions), outstanding flame resistance (LOI value of >27% and low smoke production rate), good thermal insulating performance and reliable strain sensing in various stress modes and complex environmental conditions. It provides a new route for the rational design and development of advanced PDMS foam nanocomposites with versatile multifunctionalities for various promising applications such as intelligent healthcare monitoring and fire-safe thermal insulation.     

Piezoelectric Nanostructured Surface for Ultrasound-Driven Immunoregulation to Rescue Titanium Implant Infection

Treating bacterial biofilm infections on implanted materials remains challenging in clinical practice, as bacteria can be resistant by weakening the host defense from immune cells like macrophages. Herein, a metal-piezoelectric hetero-nanostructure with mechanical energy-driven antimicrobial property is in situ constructed on the Ti implant. Under ultrasonic irradiation, the formed piezotronic Ti (piezoTi) can promote the generation of reactive oxygen species (ROS) by facilitating local charge transfer at the surface, thus leading to piezodynamic killing of Staphylococcus aureus (S. aureus) while downregulating biofilm-forming genes. In addition, the stimulated macrophages on piezoTi display potent phagocytosis and anti-bacterial activity through the activation of PI3K-AKT and MAPK pathway. As a demonstration, one-time ultrasound irradiation of piezoTi pillar implanted in an osteomyelitis model efficiently eliminates the S. aureus biofilm infection and rescues the implant with enhanced osteointegration. By the synergistic effect of ultrasound-driven piezodynamic therapy and immuno-regulation, the proposed piezoelectric nanostructured surface can endow Ti implants with highly efficient antibacterial performance in an antibiotic-free, noninvasive, and on-demand manner.     

Solid Solvation Assisted Electrical Doping Conserves High-Performance in 500 nm Active Layer Organic Solar Cells

Organic solar cells (OSCs) process fascinating solution-printing capability to achieve low-cost and large-scale manufacture. However, the rapid power conversion efficiency (PCE) decay with active layer thickness enlargement inhibits the implement of OSCs’ potential advantages. To overcome the bottlenecks of PCE decay in thick active layer OSCs, the electrical doping with componential selectivity in bulk heterojunction (BHJ) film is achieved by introducing a solid solvation additive. Benefiting from the higher exciton splitting efficiency together with the longer drift (L_dr) and diffusion (L_diff) lengths, an OSC with 100 nm BHJ film demonstrates a PCE increment from 16.44% to 18.24% with prolonged dark and illuminated storage stabilities. Applying the solid solvation assisted (SSA) doping method in the OSCs with 500 nm active layer, the PCE significantly increases by 31.9%, from the original value of 11.79% to 15.55%. It further improves to 15.84% in a ternary blend thick-film device, which is the record value to the best of our knowledge. Besides, the SSA doping narrows the PCE gap between the 0.04 and 1 cm² devices. All improvements demonstrate the great potential of SSA doping for OSC commercial manufacture, since it optimizes the photovoltaic performance under all practical conditions of long-term, thick-film, and large-area.     

BERT蒙古文词向量学习

以Word2Vec为代表的静态蒙古文词向量学习方法,将处于不同语境的多种语义词汇综合表示成一个词向量,这种上下文无关的文本表示方法对后续任务的提升非常有限。通过二次训练多语言BERT预训练模型与CRF相结合,并采用两种子词融合方式,提出一种新的蒙古文动态词向量学习方法。为验证方法的有效性,在内蒙古师范大学蒙古文硕博论文的教育领域、文学领域数据集上用不同的模型进行了同义词对比实验,并利用K-means聚类算法对蒙古文词语进行聚类分析,最后在嵌入式主题词挖掘任务中进行了验证。实验结果表明,BERT学出的词向量质量高于Word2Vec,相近词的向量在向量空间中的距离非常近,不相近词的向量较远,在主题词挖掘任务中获取的主题词有密切的关联。     

服务差异二级选址路径问题及大邻域搜索算法

在电子商务背景下,物流公司为了实现及时交付并缓解交通拥堵,可按照客户不同的服务需求,将其分为自取型和配送型,进而选择开放自助点或配送点对客户进行服务。自助点和配送点作为二级物流设施,配送中心作为一级物流设施,由此形成了二级选址-路径问题。在配送车数量约束、自助点容量约束等限制下,兼顾客户点物品回收,以总物流成本最小为目标,建立考虑服务差异的二级选址-路径问题模型。设计自适应大邻域搜索算法进行求解,通过Nguyen的2E-LRP算例进行测试,更新了1个算例的全球最优解,其余算例达到或接近最优解,平均Gap值在1.22%以内,验证了算法的有效性及良好的收敛性。实际案例模拟分析验证了模型的有效性和适用性,可以为相关物流企业提供决策依据和参考。     

太赫兹时域光谱技术在涂层检测中的研究进展

涂层结构具有美观、隔热和耐腐蚀等优点,被广泛应用于航空航天、汽车船舶制造和制药等领域。但在涂层制备和服役过程中会不可避免地出现气泡和裂纹等缺陷,且涂层厚度和均匀性会直接影响涂层寿命,因此对涂层结构的检测显得十分重要。与常规无损检测技术相比,太赫兹时域光谱(THz-TDS)技术非接触性好、抗干扰性强,适用于涂层结构快速无损检测。首先,简要地介绍了太赫兹波、太赫兹时域光谱技术和典型的太赫兹时域光谱系统;然后,详细地阐述了太赫兹时域光谱技术在光学参量、厚度和微结构检测方面的国内外研究进展,特别是太赫兹波在汽车船舶、航空航天和生物制药方向的厚度检测与成像;最后,分析了涂层结构无损检测的现状,对现有的太赫兹波检测涂层存在的问题进行了总结,并对其未来的发展进行了讨论和展望。     

考虑连锁故障的覆冰灾害下输电线路脆弱性分析模型北大核心CSCD

虽然电网鲁棒性日益增强,但部分输电线路经过区域极易遭受覆冰灾害,导致该地区发生一次故障的概率大幅增加,而一次故障将会导致电网发生二次连锁故障。针对此问题,文中首先通过蒙特卡洛法判断覆冰灾害引发的输电线路一次故障脆弱性,然后通过自组织临界理论判断由一次故障引发的输电线路二次连锁故障脆弱性,从而建立综合考虑覆冰灾害和电网物理特性的输电线路脆弱性分析模型,以潜在事故链的形式展现了电网覆冰灾害下的故障演化进程,为运维人员甄别覆冰灾害下区域电网的输电线路薄弱环节提供重要决策依据。最后通过对IEEE-39节点电力系统实例进行仿真与分析,验证了所提出模型的可行性。     

Aluminum phosphate sealing to improve insulation resistance of plasma-sprayed alumina coating

The insulation resistance of conventional atmospheric plasma-sprayed alumina coatings with 10–15% porosity is ～10¹¹ Ω. The presence of pores, lamellae boundaries, and other non-fillings dampens the insulation resistance of the coating. In the present study, aluminum phosphate was used to seal the surface of plasma-sprayed alumina coating and evaluate the effect of sealing on the insulation resistance and its thermal cycling response. Sealing was carried out with three concentrations of sealant (P/Al molar ratio of 3, 10, and 15). Characterization by X-ray diffraction and scanning electron microscopy revealed the primary sealing phase as aluminum metaphosphate and effective sealing of the pores by the aluminum phosphate phases. Insulation resistance is improved by two orders of magnitude after sealing the coated samples. Sealing with P/Al molar ratio 3 exhibited maximum insulation resistance of ～10¹³ Ω at room temperature. Thermal cycling studies between 650°C and 200°C on the sealed samples showed deterioration in thermal cycling life after sealing.     

Phase Separation Derived Core/Shell Structured Cu11V6O26/V2O5 Microspheres: First Synthesis and Excellent Lithium‐Ion Anode Performance with Outstanding Capacity Self‐Restoration

Novel amorphous vanadium oxide coated copper vanadium oxide (Cu₁₁V₆O₂₆/V₂O₅) microspheres with 3D hierarchical architecture have been successfully prepared via a microwave‐assisted solution method and subsequent annealing induced phase separation process. Pure Cu₁₁V₆O₂₆ microspheres without V₂O₅ coating are also obtained by an H₂O₂ solution dissolving treatment. When evaluated as an anode material for lithium‐ion batteries (LIBs), the as‐synthesized hybrid exhibits large reversible capacity, excellent rate capability, and outstanding capacity self‐recovery. Under the condition of high current density of 1 A g^?1, the 3D hierarchical Cu₁₁V₆O₂₆/V₂O₅ hybrid maintains a reversible capacity of ≈1110 mA h g^?1. Combined electrochemical analysis and high‐resolution transmission electron microscopy observation during cycling reveals that the amorphous V₂O₅ coating plays an important role on enhancing the electrochemical performances and capacity self‐recovery, which provides an active amorphous protective layer and abundant grain interfaces for efficient inserting and extracting of Li‐ion. As a result, this new copper vanadium oxide hybrid is proposed as a promising anode material for LIBs.     

Improvement in mechanical properties of recycled GF prepreg with CNT reinforced composites using a spray coating method

Dispersion and shape of nanoparticles, as well as interfacial conditions, add significantly to difficulties in composite manufacture. In the work reported here, an innovative method of recycling composites using out-of-date prepreg was investigated in which the carbon nanotube (CNT) on the prepreg was optimally coated. Nanocomposites utilizing the out-of-date prepreg were coated with CNT and fabricated by a sheet molding method. CNT nanofillers were observed to be uniformly dispersed on epoxy prepreg by spray coating. The mechanical and interfacial properties of these CNT coated nanocomposites were improved over those of more conventionally manufactured carbon fiber/epoxy composites. The CNT nanofillers were embedded at the epoxy and fiber interface, as a result of etching of the epoxy prepreg surface by a CNT dispersion solution which enhanced interfacial reactivity.