A Shape Memory High‐Voltage Supercapacitor with Asymmetric Organic Electrolytes for Driving an Integrated NO2 Gas Sensor

A high‐voltage supercapacitor with shape memory for driving an integrated NO₂ gas sensor is fabricated using a Norland Optical Adhesive 63 polymer substrate, which can recover the original shape after deformation by short‐time heating. The supercapacitor consists of multiwalled carbon nanotube electrodes and organic electrolyte. By using organic electrolyte consisting of adiponitrile, acetonitrile, and dimethyl carbonate in an optimized volume ratio of 1:1:1, a high operation voltage of 2 V is obtained. Furthermore, asymmetric electrolytes with different redox additives of hydroquinone and 1,4‐dihydroxyanthraquinone to the anode and cathode, respectively, enhance both capacitance and energy density by ≈40 times compared to those of supercapacitor without redox additives. The fabricated supercapacitor on the Norland Optical Adhesive 63 polymer substrate retains 95.8% of its initial capacitance after 1000 repetitive bending cycles at a bending radius of 3.8 mm. Furthermore, the folded supercapacitor recovers its shape upon heating at 70 °C for 20 s. In addition, 90% of the initial capacitance is retained even after the 20th shape recovery from folding. The fabricated supercapacitor is used to drive integrated NO₂ gas sensor on the same Norland Optical Adhesive 63 substrate attached onto skin to detect NO₂ gas, regardless of deformation due to elbow movement.     

Diversity Analysis of Relay Selection Schemes for Two-Way Wireless Relay Networks

One-way wireless relay networks have recently received a lot of attention due to their ability to provide spatial diversity in fading wireless environment. Moreover, performing single-relay selection is a very attractive method due to its cost effective implementation and superior performance. However, one-way relay networks with the half-duplex signalling suffer from a spectral efficiency loss. To overcome such a drawback, two-way wireless relay networks have been proposed and these are also the networks considered in this paper. The paper analyzes the diversity orders of various relay selection schemes, including the best-relay selection, best-worse-channel selection, and maximum-harmonic-mean selection. The analysis is done for the amplify-and-forward protocol and under the two-step and three-step transmission procedures. In particular, it is shown that full diversity orders of R and R + 1 can be achieved in a R-relay wireless network with the two-step and three-step procedures, respectively. Numerical and simulation results are provided to verify our analysis.     

Phase‐Transited Lysozyme as a Universal Route to Bioactive Hydroxyapatite Crystalline Film

A key factor for successful design of bioactive complex, organic–inorganic hybrid biomaterials is the facilitation and control of adhesion at interfaces, as many current synthetic biomaterials are inert, lacking interfacial bioactivity. In this regard, the development of a simple, unified way to biofunctionalize diverse organic and inorganic materials toward biomineralization remains a critical challenge. In this report, a universal biomimetic mineralization route that can be applied to virtually any type and morphology of scaffold materials is provided to induce nucleation and growth of hydroxyapatite (HAp) crystals based on phase‐transited lysozyme (PTL) coating. Surface‐anchored abundant functional groups in the PTL enrich the interface with strongly bonded calcium ions, facilitating the formation of HAp crystals in simulated body fluid with the morphology and alignment being similar to that observed in natural HAp in mineralized tissues. By the adhesion of amyloid contained in the PTL, such protein assembly could readily integrate HAp on ceramics, metals, semiconductors, and synthetic polymers irrespective of their size and morphology, with robust bonding stability and corresponding ultralow wear extent under normal bone pressure. This strategy successfully improves the in vivo osteoconductivity of Ti‐based implant, underpinning the expectation for such biomaterial in future biointerface and tissue engineering.     

一种高精度的电力巡检定位导航系统

文章介绍了利用现代通信技术和地理信息技术,针对电力巡检特殊要求开发出的一种基于气压海拔高度测量、支持通用分组无线业务(GPRS)无线双向通信与断点续传、地图可定制的高精度定位导航系统.阐述了该高精度定位导航系统的设计原则及其模块化功能,介绍了该系统相比于传统定位导航系统的优点,最后介绍了该系统的应用实例.     

Floating-patch MEMS antennas on HRS substrate for millimetre-wave applications

Novel floating-patch micro-electro-mechanical system (MEMS) antennas are proposed for millimetre-wave applications. The floating-patch MEMS antennas are fabricated on a high resistivity silicon (HRS) substrate using surface micromachining technology. Simulation and experimental results for reflection coefficients and radiation patterns are presented.     

Few‐Layered WS2 Nanoplates Confined in Co,N‐Doped Hollow Carbon Nanocages: Abundant WS2 Edges for Highly Sensitive Gas Sensors

Edges of 2D transition metal dichalcogenides (TMDs) are well known as highly reactive sites, thus researchers have attempted to maximize the edge site density of 2D TMDs. In this work, metal‐organic framework (MOF) templates are introduced to synthesize few‐layered WS₂ nanoplates (a lateral dimension of ≈10 nm) confined in Co, N‐doped hollow carbon nanocages (WS₂_Co‐N‐HCNCs), for highly sensitive NO₂ gas sensors. WS₂ precursors are assembled in the surface cavity of Co‐based zeolite imidazole framework (ZIF‐67) and subsequent pyrolysis produced WS₂_Co‐N‐HCNCs. During the pyrolysis, the carbonized ZIF‐67 are doped by Co and N elements, and the growth of WS₂ is effectively suppressed, creating few‐layered WS₂ nanoplates functionalized Co‐N‐HCNCs. The WS₂_Co‐N‐HCNCs exhibit outstanding NO₂ sensing characteristics at room temperature, in terms of response (48.2% to 5 ppm), selectivity, response and recovery speed, and detection limit (100 ppb). These results are attributed to the enhanced adsorption and desorption kinetics of NO₂ on abundant WS₂ edges, confined in the gas permeable HCNCs. This work opens up an efficient way for the facile synthesis of edge abundant few‐layered TMDs combined with porous carbon matrix via MOF templating route, for applications relying on highly active sites.     

A management architecture for client‐defined cloud storage services

Cloud service providers offer virtual resources to users, who then pay for as much as they use. High‐speed networks help to overcome the limitation of geographical distances between clients and cloud servers, which encourage users to adopt cloud storage services for data backup and sharing. However, users use only a few cloud storage services because of the complexity of managing multiple accounts and distributing data to store. In this paper, we propose the client‐defined management architecture (CLIMA) that redefines a storage service by coordinating multiple cloud storage services from clients. We address practical issues of coordinating multiple cloud service providers using a client‐based approach. We implement a prototype as a realization of CLIMA, which achieves both reliability and privacy protection using erasure code and higher performance by optimally scheduling data transmission. We use our prototype to evaluate the benefits of CLIMA on commercial cloud storage service providers. Finally, CLIMA empowers clients to increase the manageability and flexibility of cloud storage services. Copyright © 2015 John Wiley & Sons, Ltd.     

Performance analysis of cooperative spatial multiplexing networks with AF/DF relaying and linear receiver over Rayleigh fading channels

Cooperative spatial multiplexing (CSM) system has played an important role in wireless networks by offering a substantial improvement in multiplexing gain compared with its cooperative diversity counterpart. However, there is a limited number of research works that consider the performance of CSM systems. As such, in this paper, we have derived exact performance of CSM with amplify‐and‐forward and decode‐and‐forward relays in terms of outage capacity and ergodic capacity. We have shown that CSM systems yield a unity diversity order regardless of the number of antennas at the destination and the number of relays in the networks, which is the direct result of diversity and multiplexing gain trade‐off. Our analytical expressions are corroborated by Monte‐Carlo simulations. Copyright © 2013 John Wiley & Sons, Ltd.     

Bioinspired Interlocked and Hierarchical Design of ZnO Nanowire Arrays for Static and Dynamic Pressure‐Sensitive Electronic Skins

The development of electronic skin (e‐skin) is of great importance in human‐like robotics, healthcare, wearable electronics, and medical applications. In this paper, a bioinspired e‐skin design of hierarchical micro‐ and nano‐structured ZnO nanowire (NW) arrays in an interlocked geometry is suggested for the sensitive detection of both static and dynamic tactile stimuli through piezoresistive and piezoelectric transduction modes, respectively. The interlocked hierarchical structures enable a stress‐sensitive variation in the contact area between the interlocked ZnO NWs and also the efficient bending of ZnO NWs, which allow the sensitive detection of both static and dynamic tactile stimuli. The flexible e‐skin in a piezoresistive mode shows a high pressure sensitivity (?6.8 kPa^?1) and an ultrafast response time (<5 ms), which enables the detection of minute static pressure (0.6 Pa), vibration level (0.1 m s^?2), and sound pressure (≈57 dB). The flexible e‐skin in a piezoelectric mode is also demonstrated to be able to detect fast dynamic stimuli such as high frequency vibrations (≈250 Hz). The flexible e‐skins with both piezoresistive and piezoelectric sensing capabilities may find applications requiring both static and dynamic tactile perceptions such as robotic hands for dexterous manipulations and various healthcare monitoring devices.