Reinforced Wool Keratin Fibers via Dithiol Chain Re-bonding

Regenerated wool keratin fibers (RWKFs) have heretofore attracted tremendous interest according to environmental friendliness, ample resource, and intrinsic biocompatibility for broad applications. In this realm, both uncontrollable keratin fibril assembly procedure and resultant insufficient mechanical strength, have greatly hindered their large-scale manufacture and commercial viability. Herein, a continuous wet-spinning strategy is put forward to rebuild wool keratin into compact regenerated bio-fibers with improved strength via disulfide re-bonding. Dithiothreitol (DTT) has been introduced to renovate disulfide linkage inside keratin polypeptide chains, and bridge keratin fibrils via covalent thiol bonding to form a continuous backbone as mechanical support. A thus-derived RWKF manifests a tensile strength of 186.1 ± 7.0 MPa and Young's modulus of 7.4 ± 0.2 GPa, which exceeds those of natural wool, feathers, and regenerated wool or feather keratin fibers. The detailed wet-spinning technical parameters, such as coagulation, oxidation, and post-treatment, have been systematically optimized to guarantee the continuous preparation of high-strength regenerated keratin fibers. This work offers insight into solving the concurrent challenges for continuous manufacture of regenerated protein fibers and sustainability concerns about biomass waste.     

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.     

Vapor Phase Dealloying Derived Nanoporous Co@CoO/RuO2 Composites for Efficient and Durable Oxygen Evolution Reaction (Adv. Funct. Mater. 17/2023)

The development of low-cost and effective oxygen evolution reaction (OER) electrocatalysts to expedite the slow kinetics of water splitting is crucial for increasing the efficiency of energy conversion from electricity to hydrogen fuel. Herein, 3D bicontinuous nanoporous Co@CoO/RuO₂ composites with tunable sizes and chemical compositions are fabricated by introducing vapor phase dealloying of cobalt-based alloys. The influence of physical parameters on the formation of nanoporous Co substrates with various feature ligament sizes is systematically investigated. The CoO/RuO₂ shell is constructed by integrating a thin layer of RuO₂ on the inner surface of nanoporous Co, where the CoO interlayer is formed by annealing oxidization. The composite catalyst delivers an ultralow overpotential of 198 mV at 10 mA cm⁻², Tafel slope of 57.1 mV dec⁻¹, and long-term stability of 50 h. The superior OER activity and fast reaction kinetics are attributed to charge transfer through the coupling of Co O Ru bonds at the interface and the excellent nanopore connectivity, while the durability originates from the highly stable CoO/RuO₂ interface.     

Mitigating Surface Deficiencies of Perovskite Single Crystals Enables Efficient Solar Cells with Enhanced Moisture and Reverse-Bias Stability

Metal halide perovskite single crystals are promising for diverse optoelectronic applications due to their outstanding properties. In comparison to the bulk, the crystal surface suffers from high defect density and is moisture sensitive; however, surface modification strategies of perovskite single crystals are relatively deficient. Herein, solar cells based on methylammonium lead triiodide (MAPbI₃) thin single crystals are selected as a prototype to improve single-crystal perovskite devices by surface modification. The surface trap passivation and protection against moisture of MAPbI₃ thin single crystals are achieved by one bifunctional molecule 3-mercaptopropyl(dimethoxy)methylsilane (MDMS). The sulfur atom of MDMS can coordinate with bare Pb²⁺ of MAPbI₃ single crystals to reduce surface defect density and nonradiative recombination. As a result, the modified devices show a remarkable efficiency of 22.2%, which is the highest value for single-crystal MAPbI₃ solar cells. Moreover, MDMS modification mitigates surface ion migration, leading to enhanced reverse-bias stability. Finally, the cross-link of silane molecules forms a protective layer on the crystal surface, which results in enhanced moisture stability of both materials and devices. This work provides an effective way for surface modification of perovskite single crystals, which is important for improving the performance of single-crystal perovskite solar cells, photodetectors, X-ray detectors, etc.     

A Fullerene Seeded Strategy for Facile Construction of Nitrogen-Doped Carbon Nano-Onions as Robust Electrocatalysts

Carbon nano-onions (CNOs) as a novel form of carbon materials hold peculiar structural features but their electrocatalytic applications are largely discouraged by the demanding synthesis conditions (e.g., ≥1500 °C and vacuum). Using C₆₀ fullerene molecules as the sacrificial seeds and melamine as the main feedstock, herein, a novel strategy for the facile construction of CNOs nanoparticles is presented with ultrafine sizes (≈5 nm) at relatively low temperatures (≤900 °C) and atmospheric pressure. During the calcination, in-depth characterizations reveal that C₆₀ can retain the melamine-derived graphitic carbon nitride from complete sublimation at high temperatures (≥700 °C). Owing to the N removal and subsequent pentagon generation, severely deformed graphitic fragments together with the disintegrated C₆₀ molecules merge into larger sized nanosheets with high curvature, eventually leading to the formation of N-doped defect-rich CNOs. Owing to the integration of multiple favorable structural features of pentagons, edges, and N dopants, the CNOs obtained at 900 °C present superior oxygen reduction half-wave potential (0.853 V_RHE) and zinc–air cathode performance to the commercial Pt/C (0.838 V_RHE). Density functional theory calculation further uncovers that the carbon atoms adjacent to the N-doped edged pentagons are turned into the ORR-active sites with O₂ protonation as the rate-determining step.     

X-Board: an egocentric adaptive AR assistant for perception in indoor environments

Virtual Reality - Augmented reality (AR) has the potential to become an effective assistive technology for emergencies in the future. However, raw AR content can confuse users’ visual...     

小目标检测研究综述

随着计算机视觉和人工智能技术的快速发展,目标检测受到了更加广泛的关注。由于小目标像素占比小、语义信息少、易受复杂场景干扰以及易聚集遮挡等问题,导致小目标检测一直是目标检测领域中的一大难点。目前,视觉的小目标检测在生活的各个领域中日益重要。为了进一步促进小目标检测的发展,提高小目标检测的精度与速度,优化其算法模型,本文针对小目标检测中存在的问题,梳理了国内外研究现状及成果。首先,分别从小目标可视化特征、目标分布情况和检测环境等角度对小目标检测的难点进行了分析,同时从数据增强、超分辨率、多尺度特征融合、上下文语义信息、锚框机制、注意力机制以及特定的检测场景等方面系统总结了小目标检测方法,并整理了在框架结构、损失函数、预测和匹配机制等方面发展的较为成熟的单阶段小目标检测方法。其次,本文对小目标检测的评价指标以及可用于小目标检测的各类数据集进行了详细介绍,并针对部分经典的小目标检测方法在MSCOCO(Microsoft common objects in context)、VisDrone2021(vision meets drones2021)和Tsinghua-Tencent100K等数据...     

边界信息保持的全染色肾脏切片多粒度分割

目的 肾小球图像的准确分割对肾脏病理学的疾病诊断和定量分析起到关键作用,然而全染色肾脏切片图像存在由肾小球个体差异大导致的空间尺度和上下文形状变化大,以及图像分辨率过高的问题,给高精度、高性能分割任务带来挑战。为此,提出一种边界信息保持的全染色肾脏切片多粒度分割方法。方法 使用一种多粒度上下文的空间注意力机制生成多粒度和多形状变化的空间注意力图,以限制上下文特征,减弱背景对目标的影响,强化网络对目标的感知能力,使网络更多地关注小目标特征;将原图像切分为若干小图来解决全染色图像分辨率高的问题,使用增广路径边界补零策略处理卷积核存在的贡献偏移效应,解决了肾小球目标处于图像边界所导致的分割困难问题,保证图像块的信息无损失地向高层传递,提高处于图像块边界的肾小球目标的分割精度;进一步地,针对图像块拼接带来的边缘肾小球容易漏检、计算开销大的问题,采用特征复用的概率累积滑窗策略,同时提高了分割精度和效率。结果 在小鼠肾脏细胞切片和HuBMAP（human biomolecular atlas program）人体肾脏数据上,本文方法提高了分割精度,并使预测速度提高50%左右。结论 对于全染色肾脏切片的肾小球分割问题,多粒度上下文特征和增广路径边界补零策略解决了边界区域肾小球目标分割困难、分割精度低的问题,并通过概率累积滑窗策略提高分割速度,相较传统的分割方法有更优秀的性能。     

欺骗攻击下弹性自触发模型预测控制

针对在欺骗攻击下自触发模型预测控制系统的安全控制问题, 本文提出一种基于关键数据保护的弹性自 触发模型预测控制(MPC)策略. 对比现有的自触发MPC, 该方法仅需对少量关键控制样本进行保护, 则可保证闭环 系统稳定运行, 从而有效节省系统资源. 首先, 基于自触发MPC和欺骗攻击的特征推导标称系统与被攻击系统状态之间的误差上界, 从而定量分析出欺骗攻击对系统的损害. 然后, 通过所获得误差上界和李雅普诺夫定理建立关键数据的选取条件并对其实施保护. 最后, 严格证明了在仅对关键控制样本实施保护后, 被控系统仍可在欺骗攻击下保持稳定. 此外, 基于移动机器人和弹簧小车系统对所提算法进行了仿真实验, 结果表明所提算法能够显著节省保护资源, 验证了算法的有效性     

RTDMiner: 基于数据挖掘的引用计数更新缺陷检测方法

在Linux内核等大型底层系统中广泛采用引用计数来管理共享资源.引用计数需要与引用资源的对象个数保持一致,否则可能导致不恰当引用计数更新缺陷,使得资源永远无法释放或者被提前释放.为检测不恰当引用计数更新缺陷,现有静态检测方法通常需要知道哪些函数增加引用计数,哪些函数减少引用计数.而手动获取这些关于引用计数的先验知识过于费时且可能有遗漏.基于挖掘的缺陷检测方法虽然可以减少对先验知识的依赖,但难以有效检测像不恰当引用计数更新缺陷这类路径敏感的缺陷.为此,提出一个将数据挖掘技术和静态分析技术深度融合的不恰当引用计数更新缺陷检测方法 RTDMiner.首先,根据引用计数的通用规律,利用数据挖掘技术从大规模代码中自动识别增加或减少引用计数的函数.然后,采用路径敏感的静态分析方法检测增加了引用计数但没有减少引用计数的缺陷路径.为了降低误报,在检测阶段再次利用数据挖掘技术来识别例外模式.在Linux内核上的实验结果表明,所提方法能够以将近90%的准确率自动识别增加或减少引用计数的函数.而且RTDMiner检测到的排行靠前的50个疑似缺陷中已经有24个被内核维护人员确认为真实缺陷.