Regulating the synergy coefficient of composite materials for alleviating self-discharge of supercapacitors

Supercapacitor is an efficient energy storage device,yet its wider application is still limited by self-discharge.Currently,various composite materials have been reported to have improved inhibition on self-discharge,while the evaluation of the synergistic effect in composite materials is challenging.Herein,pairs of intercalation type pseudocapacitive niobium oxides are pre-lithiated and coupled to construct conjugatedly configured supercapacitors,within which the cathode and anode experience identical reaction environment with single type of charge carrier,thus providing ideal platform to quantify the synergistic effect of composite materials on the self-discharge process.By using titanium dioxide as the stabilizer,we have compared how the modes of forming composite would influence the selfdischarge performance of the active composite materials with similar ratio of the constituent materials.Specifically,core@shell Nb_(2)O_(5)@TiO_(2) composite using TiO_(2) as the shell shows significantly higher synergy coefficient(μ=0.61,defined as the value that evaluates the synergistic effect between composite materials,and can be quantified using the overall performance of the composite,performance of individual component as well as the ratio of the component.) than other control group samples,which corresponds to the highest retained energy of 63% at 100 h.This work is expected to provide a general method for quantifying the synergistic effect and guide the design of composite materials with specific mode of forming the composite.

A miniaturized transit-time ultrasonic flowmeter based on ScAIN piezoelectric micromachined ultrasonic transducers for small-diameter applications

Transit-time ultrasonic flowmeters(TTUFs)are among the most widely used devices for flow measurements.However,traditional TTUFs are usually based on a bulk piezoelectric transducer,which limits their application in small-diameter channels.In this paper,we developed a miniaturized TTUF based on scandium-doped aluminum nitride(ScAIN)piezoelectric micromachined ultrasonic transducers(PMUTs).The proposed TTUF contains two PMUT-based transceivers and a T-type channel.The PMUTs contain 13×13 square cells with dimensions of 2.8×2.8 mm^(2).To compensate for the acoustic impedance mismatch with liquid,a layer of polyurethane is added to the surface of the PMUTs as a matching layer.The PMUT-based transceivers show good transmitting sensitivity(with 0.94 MPaN surface pressure)and receiving sensitivity(1.79 mV/kPa)at a frequency of 1 MHz in water.Moreover,the dimensions of the Ttype channel are optimized to achieve a measurement sensitivity of 82 ns/(m/s)and a signal-to-noise ratio(SNR)better than 15 dB.Finally,we integrate the fabricated PMUTs into the TDC-GP30 platform.The experimental results show that the developed TTUF provides a wide range of flow measurements from 2 to 300 L/h in a channel of 4 mm diameter,which is smaller than most reported channels.The accuracy and repeatability of the TTUF are within 0.2%and 1%,respectively.The proposed TTUF shows great application potential in industrial applications such as medical and Chemical applications.

Nlrc3-like is required for microglia maintenance in zebrafish

Microglia are tissue-resident macrophages residing in the central nervous system (CNS) and play critical roles in removing cellular debris and infectious agents as well as regulating neurogenesis and neuronal activities. Yet, the molecular basis underlying the establishment of microglia pool and the maintenance of their homeostasis in the CNS remain largely undefined. Here we report the identification and characterization of a mutant zebrafish, which harbors a point mutation in the nucleotide-binding oligomerization domain (NOD) like receptor gene nlrc3-like, resulting in the loss of microglia in a temperature sensitive manner. Temperature shift assay reveals that the late onset of nlrc3-like deficiency leads to excessive microglia cell death. Further analysis shows that the excessive microglia death in nlrc3-like deficient mutants is attributed, at least in part, to aberrant activation of canonical inflammasome pathway. Our study indicates that proper regulation of inflammasome cascade is critical for the maintenance of microglia homeostasis.

Beyond fundamental resonance mode:high-order multi-band ALN PMUT for in vivo photoacoustic imaging

This paper reports on an aluminum nitride(AlN)piezoelectric micromachined ultrasound transducer(PMUT)array for photoacoustic(PA)imaging,where the high-order resonance modes of the PMUT are utilized to improve imaging resolution.A flexural vibration mode(FVM)PMUT is fabricated and applied in a photoacoustic imaging(PAI)system.Specifically,the microelectromechanical system(MEMS)-based PMUT is suitable for PA endoscopic imaging of blood vessels and bronchi due to its miniature size and high sensitivity.More importantly,AlN is a nontoxic material,which makes it harmless for biomedical applications.In the PAI system,the AlN PMUT array is used to detect PA signals,and the acousto–mechanical response is designed and optimized at the PMUT’s fundamental resonance.In this work,we focus on the high-order resonance performance of the PMUT PAI beyond the fundamental resonance.The acoustic and electrical responses of the PMUT’s high-order resonance modes are characterized and analyzed.The fundamental and three high-order resonance bandwidths are 2.2,8.8,18.5,and 48.2 kHz.Compared with the resolution at the fundamental resonance mode,the resolutions at third-and fourth-order resonance modes increase by 38.7%and 76.9%in a phantom experiment.The high-order resonance modes of the AlN PMUT sensor array provide higher central frequency and wider bandwidth for PA signal detection,which increase the resolution of PAI compared to the PMUT working at the fundamental resonance mode.