Engineering Cathode-Electrolyte Interface of High-Voltage Spinel LiNi0.5Mn1.5O4 via Halide Solid-State Electrolyte Coating.

The high-voltage spinel LiNi0.5Mn1.5O4 (LNMO) cathode material with high energy density, low cost, and excellent rate capability has grabbed the attention of the field. However, a high-voltage platform at 4.7 V causes severe oxidative side reactions when in contact with the organic electrolyte, leading to poor electrochemical performance. Furthermore, the contact between the liquid electrolyte and LNMO leads to Mn dissolution during cycles. In this work, we applied the sol-gel method to prepare Li3InCl6-coated LNMO (LIC@LNMO) to address the mentioned problems of LNMO. By introducing a protective layer of halide-type solid-state electrolyte on LNMO, we can prevent direct contact between LNMO and electrolyte while maintaining good ionic conductivity. Thus, we could demonstrate that 5 wt % LIC@LNMO exhibited a good cycle performance with a Coulombic efficiency of 99% and a capacity retention of 80% after the 230th cycle at the 230th cycle at 1C at room temperature.

A programmable DNA nanodevice for colorimetric detection of DNA methyltransferase activity using functionalized hemin/G-quadruplex DNAzyme.

The measurement of DNA methyltransferase (MTase) activity and screening of DNA MTase inhibitors holds significant importance for the diagnosis and therapy of methylation-related illness. Herein, we developed a colorimetric biosensor (PER-FHGD nanodevice) to detect DNA MTase activity by integrating the primer exchange reaction (PER) amplification and functionalized hemin/G-quadruplex DNAzyme (FHGD). By replacing the native hemin cofactor into the functionalized cofactor mimics, FHGD has exhibited significantly improved catalytic efficiency, thereby enhancing the detection performance of the FHGD-based system. The proposed PER-FHGD system is capable of detecting Dam MTase with excellent sensitivity, exhibiting a limit of detection (LOD) as low as 0.3 U/mL. Additionally, this assay demonstrates remarkable selectivity and ability for Dam MTase inhibitors screening. Furthermore, using this assay, we successfully detect the Dam MTase activity both in serum and in E. coli cell extracts. Importantly, this system has the potential to serve as a universal strategy for FHGD-based diagnosis in point-of-care (POC) tests, by simply altering the recognition sequence of the substrate for other analytes.

Influence of different fibers on compressive toughness and damage of early age cemented tailings backfill.

For improving the utilization rate of tailings and the safety of cemented tailings backfill (CTB) as earthwork materials, the influence of three types of fibers (e.g., glass, polyacrylonitrile and mixture fibers of both) on compressive toughness and damage of early age CTB was studied. An equation for quantitative analysis of compressive toughness of fiber-reinforced CTB was established. An uniaxial compression test was carried out to monitor the damage acoustic emission (AE) activities of CTB during the loading process. Then, the microstructure of CTB after uniaxial compression test was observed by scanning electron microscope (SEM). The results indicated that mixed fiber has the most comprehensive reinforcement effect on compressive toughness and peak load of CTB. Three fibers inhibited the crack development rate of CTB, glass fiber mainly absorbed axial strain energy of CTB before peak load, while polyacrylonitrile fiber mainly absorbed fracture energy generated during the crack development of CTB after peak load, mixed fiber combined their advantages. The AE activities of three fiber-reinforced CTB samples are much stronger than those of non-reinforced CTB samples in the loading process, and these are no "quiet period" of AE activities. Three fibers all improved the durability of CTB in the damage process, and the damage process of mixed fiber-reinforced CTB is the most stable and showed an approximate linear growth trend. Polyacrylonitrile fiber has a strong resistance to crack after the peak load of CTB because of its ellipsoid part on the surface. As a result, this study can provide a theoretical reference for construction units to use fiber-reinforced CTB for engineering applications and filling work.

One-Pot Synthesis of Chlorophyll-Assisted Exfoliated MoS2/WS2 Heterostructures via Liquid-Phase Exfoliation Method for Photocatalytic Hydrogen Production.

Developing strategies for producing hydrogen economically and in greener ways is still an unaccomplished goal. Photoelectrochemical (PEC) water splitting using photoelectrodes under neutral electrolyte conditions provides possibly one of the greenest routes to produce hydrogen. Here, we demonstrate that chlorophyll extracts can be used as an efficient exfoliant to exfoliate bulk MoS2 and WS2 to form a thin layer of a MoS2/WS2 heterostructure. Thin films of solution-processed MoS2 and WS2 nanosheets display photocurrent densities of -1 and -5 mA/cm2, respectively, and hydrogen evolution under simulated solar irradiation. The exfoliated WS2 is significantly more efficient than the exfoliated MoS2; however, the MoS2/WS2 heterostructure results in a 2500% increase in photocurrent densities compared to the individual constituents and over 12 h of PEC durability under a neutral electrolyte. Surprisingly, in real seawater, the MoS2/WS2 heterostructure exhibits stable hydrogen production after solar illumination for 12 h. The synthesis method showed, for the first time, how the MoS2/WS2 heterostructure can be used to produce hydrogen effectively. Our findings highlight the prospects for this heterostructure, which could be coupled with various processes towards improving PEC efficiency and applications.

A New Ticket-Based Authentication Mechanism for Fast Handover in Mesh Network.

Due to the ever-growing popularity mobile devices of various kinds have received worldwide, the demands on large-scale wireless network infrastructure development and enhancement have been rapidly swelling in recent years. A mobile device holder can get online at a wireless network access point, which covers a limited area. When the client leaves the access point, there will be a temporary disconnection until he/she enters the coverage of another access point. Even when the coverages of two neighboring access points overlap, there is still work to do to make the wireless connection smoothly continue. The action of one wireless network access point passing a client to another access point is referred to as the handover. During handover, for security concerns, the client and the new access point should perform mutual authentication before any Internet access service is practically gained/provided. If the handover protocol is inefficient, in some cases discontinued Internet service will happen. In 2013, Li et al. proposed a fast handover authentication mechanism for wireless mesh network (WMN) based on tickets. Unfortunately, Li et al.'s work came with some weaknesses. For one thing, some sensitive information such as the time and date of expiration is sent in plaintext, which increases security risks. For another, Li et al.'s protocol includes the use of high-quality tamper-proof devices (TPDs), and this unreasonably high equipment requirement limits its applicability. In this paper, we shall propose a new efficient handover authentication mechanism. The new mechanism offers a higher level of security on a more scalable ground with the client's privacy better preserved. The results of our performance analysis suggest that our new mechanism is superior to some similar mechanisms in terms of authentication delay.

An enhanced mobile-healthcare emergency system based on extended chaotic maps.

Mobile Healthcare (m-Healthcare) systems, namely smartphone applications of pervasive computing that utilize wireless body sensor networks (BSNs), have recently been proposed to provide smartphone users with health monitoring services and received great attentions. An m-Healthcare system with flaws, however, may leak out the smartphone user's personal information and cause security, privacy preservation, or user anonymity problems. In 2012, Lu et al. proposed a secure and privacy-preserving opportunistic computing (SPOC) framework for mobile-Healthcare emergency. The brilliant SPOC framework can opportunistically gather resources on the smartphone such as computing power and energy to process the computing-intensive personal health information (PHI) in case of an m-Healthcare emergency with minimal privacy disclosure. To balance between the hazard of PHI privacy disclosure and the necessity of PHI processing and transmission in m-Healthcare emergency, in their SPOC framework, Lu et al. introduced an efficient user-centric privacy access control system which they built on the basis of an attribute-based access control mechanism and a new privacy-preserving scalar product computation (PPSPC) technique. However, we found out that Lu et al.'s protocol still has some secure flaws such as user anonymity and mutual authentication. To fix those problems and further enhance the computation efficiency of Lu et al.'s protocol, in this article, the authors will present an improved mobile-Healthcare emergency system based on extended chaotic maps. The new system is capable of not only providing flawless user anonymity and mutual authentication but also reducing the computation cost.