基于超像素暗通道和自动色阶优化的图像去雾算法

针对暗通道先验(dark channel prior, DCP)复原图像中的光晕现象、明亮区域色彩失真、环境光估计不准确等问题,提出了基于超像素暗通道和自动色阶优化的单幅图像去雾算法。首先,由改进的White Patch Retinex算法增强图像并计算精确环境光。接着,在传统暗通道去雾算法中引入超像素图像分割和引导滤波算法,使透射率估计的稳健性与精确性得以提升。然后,采用自适应容差对明亮区域的透射率进行补偿,有效抑制明亮区域色彩失真问题。最后,以自动色阶优化算法提高图像对比度。将本文去雾算法与其他算法从主观和客观两个维度进行比较,实验结果表明：采用不同算法对不同浓度的自然雾图进行对比实验,信息熵提高0.2 bit,峰值信噪比(peak signal-to-noise ratio,PSNR)提高0.8 dB,运行效率提高。该算法对不同浓度含雾图像具有良好的适应性,复原图像色彩真实、纹理清晰、细节丰富,去雾效果良好。     

Development of an Asymmetric Hydrophobic/Hydrophilic Ultrathin Graphene Oxide Membrane as Actuator and Conformable Patch for Heart Repair

A conductive engineered cardiac patch (ECP) can reconstruct the biomimetic regenerative microenvironment of an infarcted myocardium. Direct ink writing (DIW) and 3D printing can produce an ECP with precisely controlled microarchitectures. However, developing a printed ECP with high conductivity and flexibility for gapless attachment to conform to epicardial geometry remains a challenge. Herein, an asymmetrical DIW hydrophobic/hydrophilic membrane using heat-processed graphene oxide (GO) ink is developed. The “Masked spin coating” method is also developed that leads to a microscale GO (hydrophilic)/reduced GO (rGO, hydrophobic) physiological sensor, as well as a macroscale moisture-driven GO/rGO actuator. Depositing mussel-inspired polydopamine (PDA) coating on the one side of the DIW rGO , the ultrathin (approximately 500 nm) PDA-rGO (hydrophilic)/rGO (hydrophobic) microlattice (DrGOM) ECP is bestowed with the flexibility and moisture-responsive actuation that allows gapless attachment to the curved surface of the epicardium. Conformable DrGOM exhibits a promising therapeutic effect on rats' infarcted hearts through conductive microenvironment reconstruction and improved neovascularization.     

Ni3N–CeO2 Heterostructure Bifunctional Catalysts for Electrochemical Water Splitting

Developing low-cost and high-efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni₃N-CeO₂/NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni₃N-CeO₂/NF bifunctional catalyst only needs 1.515 V@10 mA cm⁻², significantly better than that of Pt/C||IrO₂ catalysts. In situ characterizations unveil that CeO₂ plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO₂ can optimizes the structure of interface water, and the synergistic effect of Ni₃N and CeO₂ improve the HER activity significantly, while the in situ Raman spectra reveal that CeO₂ accelerates the reconstruction of O_V (oxygen vacancy)-rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO₂ for boosting the HER and OER activity of Ni₃N for water splitting, which provides the useful guidance for designing the high-performance bifunctional catalysts for water splitting.     

An Apoptotic Body-based Vehicle with Navigation for Photothermal-Immunotherapy by Precise Delivery and Tumor Microenvironment Regulation

Tumor precision therapy and preventing tumor recurrence and metastasis are the main challenges to tumor eradication. Herein, an apoptotic body-based vehicle with imaging navigation is developed for precise tumor delivery and photothermal-immunotherapy by IR820-conjugated apoptotic body loaded with R848 nanoparticles. The apoptotic body serves as ammunition stores as well as vehicle drive engines, while IR820 acts as a fluorescence imaging navigation and photothermal controlling system. The apoptotic body vehicle can deliver the ammunition to tumor and achieve deep penetration by macrophage-hitchhiking. Fluorescence imaging navigation opens a control window for photothermal treatment, followed by photothermal triggering of in situ vaccine formation. Further, CD47 antibody loaded hydrogel strengthens innate and adaptive immunity, simultaneously the polarization of macrophages regulates the immunosuppressive microenvironment to further promote the combined antitumor immunotherapy. With breast tumor (4T1)-bearing mice model, the apoptotic body vehicle performs excellent therapeutic efficacy for primary tumor, distant tumor, tumor metastasis, and recurrence prevention.     

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.     

基于富铟团簇量子结构的双波长可调谐半导体激光器

本研究提出了一种采用增益芯片和光栅外腔的双波长可调谐半导体激光器。增益芯片采用了富铟团簇量子限制结构作为其量子限制结构,由于该结构独特的平顶增益特性,可以使激光器在双波长调谐范围内实现光强稳定。本研究中的谐振腔包括内部谐振腔和外部谐振腔,其中内部谐振腔由增益芯片的两个自然解理面构成,以支撑整个系统工作在特定波长。外部谐振腔由增益芯片的一个自然解理面和光栅构成,可实现969.1~977.9 nm的工作波长范围。最终该系统基于单个增益芯片和单个光栅实现了同步双波长输出,双波长的频率差在THz范围。本研究有望为实现双波长差频太赫兹源提供一种可能的解决方案。     

基于钛相变边缘传感器的超导单光子探测器特性

研究了基于钛TES的超导单光子探测器的特性,器件尺寸范围为5 μm×5 μm到20 μm×20 μm,集成光学腔体后在1 550 nm波长实测的系统探测效率最高达到72%,最佳能量分辨率为0.26 eV。在此基础上,采用二流体模型提取了基于钛TES的超导单光子探测器的特性参数（包括温度灵敏度、电流灵敏度、热容等）,并模拟计算了基于钛TES的超导单光子探测器的响应时间和能量分辨率,与实验结果完全吻合。结果表明优化探测器尺寸和临界温度,可以同时达到高探测效率和高能量分辨率,实现光子数可分辨的高性能单光子探测器。     

Long-term ultra-precision phase synchronization technique for locking the repetition rate of OFCs based on FLOM-PD

Long-term ultra-precision synchronization between optical frequency combs (OFCs) and microwave oscillators is important for various fields, including scientific observation, smart grid, positioning and navigation, etc. Here, a phase-locked loop system based on fiber loop optical-microwave phase detector (FLOM-PD) is proposed to realize the synchronization of the repetition rate of OFCs and rubidium atomic clocks. Firstly, the scheme and locking process of the system are elaborated, then the mathematical model of the system is established, and the feasibility of the scheme is proved by theoretical analysis and experimental verification. After synchronization, the instability of the system reaches 8.69×10-12 at 1 s and 2.94×10-13 at 1 000 s, indicating that the phase synchronization system can achieve ultra-precision and stability of OFCs repetition rate.     

视频合成孔径雷达双域联合运动目标检测方法

视频合成孔径雷达(SAR)具有高帧率成像能力,可作为地面运动目标探测的重要技术手段。经典SAR地面动目标显示(SAR-GMTI)依靠目标回波能量来实现动目标检测,同时动目标阴影亦可作为视频SAR动目标检测的重要途径。然而,由于动目标能量和阴影的畸变或涂抹,依靠单一方式难以实现稳健的动目标检测。该文基于目标能量和阴影的双域联合检测思想,分别通过快速区域卷积神经网络和航迹关联两种技术途径实现了视频SAR动目标联合检测,给出了机载实测数据处理结果,并进行了详细分析。该文方法充分利用目标阴影与能量的特征及空时信息,提升了机动目标检测的稳健性。