Improved Flexible Triboelectric Nanogenerator Based on Tile-Nanostructure for Wireless Human Health Monitor

Triboelectric nanogenerators(TENGs)have emerged as promising candidates for integrating with flexible electronics as self-powered systems owing to their intrinsic flexibility,biocompatibility,and miniaturization.In this study,an improved flexible TENG with a tile-nanostructured MXene/polymethyl methacrylate(PMMA)composite electrode(MP-TENG)is proposed for use in wireless human health monitor.The multifunctional tile-nanostructured MXene/PMMA film,which is self-assembled through vacuum filtration,exhibits good conductivity,excellent charge capacity,and high flexibility.Thus,the MXene/PMMA composite electrode can simultaneously function as a charge-generating,charge-trapping,and charge-collecting layer.Furthermore,the charge-trapping capacity of a tile nanostructure can be optimized on the basis of the PMMA concentration.At a mass fraction of 4%PMMA,the MP-TENG achieves the optimal output performance,with an output voltage of 37.8 V,an output current of 1.8μA,and transferred charge of 14.1 nC.The output power is enhanced over twofold compared with the pure MXene-based TENG.Moreover,the MP-TENG has sufficient power capacity and durability to power small electronic devices.Finally,a wireless human motion monitor based on the MP-TENG is utilized to detect physiological signals in various kinematic motions.Consequently,the proposed performance-enhanced MP-TENG proves a considerable potential for use in health monitoring,telemedicine,and self-powered systems.

Brønsted-acid sites induced photocatalytic cracking of low-polarity polyethylene plastics

Polyolefins such as polyethylene(PE)are one of the largest-scale synthetic plastics and play a key role in modern society.However,polyethylene is extremely inert to chemical recycling owing to its lack of chemical functionality and low polarity,making it one of the most challenging environmental hazards globally.Herein,we developed a phosphorylated CeO_(2)catalyst by an organophosphate precursor and featured efficient photocatalysis of low-density polyethylene(LDPE)without the acid or alkaline pre-treatment.Compared to pristine CeO_(2),the surface phosphorylation allows to introduce Brønsted acid sites,which facilitate to form carbonium ions on LDPE via protonation.In addition,the suitable band structure of the phosphorylated CeO_(2)catalyst enables efficient photoabsorption and generates reactive oxygen species,leading to the C–C bond cleavage of LDPE.As a result,the phosphorylated CeO_(2)catalyst exhibited an outstanding carbon conversion rate of>94%after 48 h of photocatalysis under 50 mW/cm^(2)of simulated sunlight,with a high CO_(2)product selectivity of>99%.Furthermore,the PE microparticles with sizes larger than 10μm released from LDPE plastic wrap were directly and completely degraded by photocatalysis within 12 h,suggesting an attractive and environmentally benign strategy of utilizing solar energy-based photocatalysis for reducing potential hazards of LDPE plastic trashes.

Copper‐doped nickel oxyhydroxide for efficient electrocatalytic ethanol oxidation

Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.

Analysis of Fluid Model Modulated by an M/PH/1 Working Vacation Queue

We propose a fluid model driven by the queue length process of a working vacation queue with PH service distribution, which can be applied to the Ad Hoc network with every data group. We obtain the stationary distribution of the queue length in driving process based on a quasi-birth-and-death process. Then, we analyze the fluid model, and derive the differential equations satisfied by the stationary joint distribution of the fluid queue based on the balance equation. Moreover, we obtain some performance indices, such as, the average throughput, server utilization and the mean buffer content. These indices are relevant to pack transmission in the network, and they can be obtained by using the Laplace Transform (LT) and the Laplace-Stieltjes Transform (LST). Finally, some numerical examples have been discussed with respect to the effect of several parameters on the system performance indices.

Mechanical properties and biocompatibility of polymer infiltrated sodium aluminum silicate restorative composites

A new type of polymer-infiltrated-ceramic-network composites (PICNs) was fabricated by infiltrating methacrylate-based monomers into partially sintered porous ceramics.The mechanical properties (flexural strength,flexural modulus,elastic modulus,Vickers hardness,fracture toughness) were investigated and compared with that of the natural tooth and common commercial CAD/CAM blocks.Our results indicated that sintering temperature and corresponding density of porous ceramics have an obvious influence on the mechanical properties,and PICNs could highly mimic the natural tooth in mechanical properties.The biocompatibility experiments evaluated through in vitro cell attachment and proliferation of BMSCs showed good biocompatibility.The mechanical properties and biocompatibility confirmed that PICN could be a promising candidate for CAD/CAM blocks for dental restoration.