Piezoresistive Pressure Sensor Based on Synergistical Innerconnect Polyvinyl Alcohol Nanowires/Wrinkled Graphene Film

Piezoresistive sensor is a promising pressure sensor due to its attractive advantages including uncomplicated signal collection, simple manufacture, economical and practical characteristics. Here, a flexible and highly sensitive pressure sensor based on wrinkled graphene film (WGF)/innerconnected polyvinyl alcohol (PVA) nanowires/interdigital electrodes is fabricated. Due to the synergistic effect between WGF and innerconnected PVA nanowires, the as‐prepared pressure sensor realizes a high sensitivity of 28.34 kPa^?1. In addition, the device is able to discern lightweight rice about 22.4 mg (≈2.24 Pa) and shows excellent durability and reliability after 6000 repeated loading and unloading cycles. What is more, the device can detect subtle pulse beat and monitor various human movement behaviors in real‐time.     

UV Photodetectors Based on BiOCl Nanosheet Arrays: The Effects of Morphologies and Electrode Configurations

A facile chemical bath method is adopted to grow bismuth oxychloride (BiOCl) nanosheet arrays on a piece of Cu foil (denoted as BiOCl‐Cu) and isolated BiOCl nanosheets are collected by ultrasonication. A self‐supporting BiOCl film is obtained by the removal of Cu foil. Photodetectors (PDs) based on these BiOCl materials are assembled and the effects of morphologies and electrode configurations on the photoelectric performance of these PDs are examined. The BiOCl nanosheet PD achieves high responsivities in the spectral range from 250 to 350 nm, while it presents quite a small photocurrent and slow response speed. The BiOCl film PD yields low photocurrents and near‐unity on–off ratios, demonstrating poor photoelectric performance. The photocurrent of the BiOCl‐Cu PD with both electrodes on the BiOCl film is much higher than those of these above‐mentioned PDs, and the response times are fast. Meanwhile, the BiOCl‐Cu PD with separate electrodes on the BiOCl film and Cu foil achieves even higher photocurrents and presents a self‐powering characteristic, depicting the improved photodetecting performances induced by the specific morphology and distinct electrode configuration. These results would promote the applications of BiOCl nanostructures in the photoelectric devices.     

铝合金在盐水环境中腐蚀性能的电化学研究

为了深入研究温度对铝合金材料的腐蚀行为和机理,采用盐水腐蚀方法研究了其在高温条件下的电化学特性及腐蚀机理.选用7A04和5A06铝合金作为研究对象,在质量分数为3.5%的氯化钠溶液中,利用增重法、蔡司显微镜并结合电化学测试方法研究了其在20~80 ℃范围内的腐蚀性能,分析了腐蚀产物的微观形貌,探讨了腐蚀机理.结果表明：两种铝合金试样的腐蚀速率均随温度升高而增大.在Tafel极化曲线图中,对于同一种铝合金,自腐蚀电位随腐蚀温度增加向负方向移动,自腐蚀电流密度和年腐蚀深度随腐蚀温度增加而减小.对同一腐蚀温度下的两种铝合金,5A06铝合金自腐蚀电位低于7A04铝合金,腐蚀电流密度和年腐蚀深度均小于7A04铝合金.电化学阻抗图谱中,两种铝合金在不同条件下的Nyquist图均存在一个容抗弧,极化电阻随腐蚀温度增加而减小.对于同一种铝合金,在3.5%氯化钠溶液中的腐蚀速率会随着温度的升高而增大;在同一腐蚀温度下,5A06铝合金比7A04铝合金更容易发生腐蚀,但腐蚀速率比7A04铝合金慢.     

Hybridized electronic states between CdSe nanoparticles and conjugated organic ligands: A theoretical and ultrafast photo-excited carrier dynamics study

Formation of densely packed thin films of semiconductor nanocrystals is advantageous for the exploitation of their unique optoelectronic properties for real-world applications. Here we investigate the fundamental role of the structure of the bridging ligand on the optoelectronic properties of the resulting hybrid film. In particular, we considered hybrid films formed using the same CdSe nanocrystals and two organic ligands that have the same bidentate dithiocarbamate binding moiety, but differ in their bridging structures, one bridged by ethylene, the other by phenylene that exhibits conjugation. Based on the results of photo-excited carrier dynamics experiments combined with theoretical calculations on the electronic states of bridged CdSe layers, we show that only the phenylene-based ligand presents a strong hybridization of the molecular HOMO state with CdSe layers, that is a marker of formation of an effective bridge. We argue that this hybridization spread favors the hopping of photo-excited carriers between nanocrystals, which may explain the reported larger photo-currents in phenylene-based hybrid films than those observed in ethylene-based ones.

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Highly uniform ultrasound-sensitive nanospheres produced by a pH-induced micelle-to-vesicle transition for tumor-targeted drug delivery

Although gas-filled microbubbles with high echogenicity are widely applied inclinical ultrasonography, the micron scale particle size impedes their use in the treatment of solid tumors,which are accessible to objects less than several hundred nanometers. We herein propose an unusual approach involving apH-induced core–shell micelle-to-vesicle transition to prepare ultrasound-sensitive polymeric nanospheres (polymersomes in structure) possessing multiple features, including nanosize, monodispersity, and incorporation of a phase-transitional imaging agent into the aqueous lumen. These features are not achievable via the conventional double-emulsion method for polymersome preparation. The nanospheres were constructed based on a novel triblock copolymer with dual pH sensitivity. The liquid-to-gas phase transition of the imaging agent induced by external low-frequency ultrasound may destroy the nanospheres for a rapid drug release, with simultaneous tissue-penetrating drug delivery inside a tumor. These effects may provide new opportunities for the development of an effective cancer therapy with few adverse effects.

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Visible light-driven superoxide generation by conjugated polymers for organic synthesis

Nano Research - Benefiting from their unique delocalized electronic structure, conjugated polymer-based semiconductors are widely applied in the fields of organic electronics, sensors, and...     

基于直推式学习的网络故障诊断算法

网络故障的及时诊断能够保证日常工作、学习和生活能够正常进行,传统的基于监督式学习的诊断方法依赖于大量具有鉴别意义的样本,这在实际情况中通常难以得到满足;针对上述问题,提出了一种基于直推式学习的诊断算法;针对大规模的网络管理的特征数据,该算法利用主成分分析对特征进行降维,并利用新的度量下的特征数据来构建拉普拉斯矩阵;该矩阵能够很好地描述带检测样本和训练样本之间的关系;在此基础上,设计了基于直推式学习的目标函数,并利用拉格朗日乘子法完成了优化;实验部分证明了本算法能够在有限数目的带标签的样本的前提下获得精确的分类结果,能够显著提高网络故障诊断的检测率。     

一种数字图像技术实现应变测量的设计与实验对比

基于数字图像处理技术设计实现了其在应变测量领域应用,采用了位移场-牛顿迭代法、应变估计处理进行了理论设计分析;在铝合金材料的变形测量实验中通过铝合金材料拉伸应变仪记录与数字图像设计方法对比得出:采用数字图像应变测量与记录仪基本一致,可以实现应变测量;构件表面散斑颗粒大小对设计的数字图像应变测量会产生一定的影响;文中设计的方法不仅实现了应变测量精度的改进,还提供了一种易于实施、有效的技术手段。