Monolithic epitaxy and optoelectronic properties of single-crystalline γ-In_(2)Se_(3) thin films on mica

The growth of γ-In_(2)Se_(3) thin films on mica by molecular beam epitaxy is studied. Single-crystalline γ-In_(2)Se_(3) is achieved at a relatively low growth temperature. An ultrathin β-In_(2)Se_(3) buffer layer is observed to nucleate and grow through a process of self-organization at initial deposition, which facilitates subsequent monolithic epitaxy of single-crystallineγ-In_(2)Se_(3) at low temperature. Strong room-temperature photoluminescence and moderate optoelectronic response are observed in the achieved γ-In_(2)Se_(3) thin films.

Robust hydrogel sensors for unsupervised learning enabled sign-to-verbal translation

Highly stretchable and robust strain sensors are rapidly emerging as promising candidates for a diverse of wearable electronics.The main challenge for the practical application of wearable electronics is the energy consumption and device aging.Energy consumption mainly depends on the conductivity of the sensor,and it is a key factor in determining device aging.Here,we design a liq-uid metal(LM)-embedded hydrogel as a sensing material to overcome the bar-rier of energy consumption and device aging of wearable electronics.The sensing material simultaneously exhibits high conductivity(up to 22 S m�1),low elastic modulus(23 kPa),and ultrahigh stretchability(1500%)with excel-lent robustness(consistent performance against 12000 mechanical cycling).A motion monitoring system is composed of intrinsically soft LM-embedded hydrogel as sensing material,a microcontroller,signal-processing circuits,Bluetooth transceiver,and self-organizing map developed software for the visu-alization of multi-dimensional data.This system integrating multiple functions including signal conditioning,processing,and wireless transmission achieves monitor hand gesture as well as sign-to-verbal translation.This approach provides an ideal strategy for deaf-mute communicating with normal people and broadens the application of wearable electronics.

Visual servoing-based pneumatic hair transplantation mechanism for robotic FUE surgery

Hair transplantation surgery is an effective solution for hair loss problems,among which follicle unit extraction(FUE)surgery is more widely used and favored.At present,most hair transplantation surgeries still rely heavily on manual operation by doctors and very few hair transplantation robots with complex structures have been introduced.This paper proposes a pneumatic hair transplantation mechanism for FUE surgery,equipped with a camera,capable of automatically performing both hair implantation and extraction with airflow.This pneumatic method eliminates the complex needle structure,has the function of temporarily storing the follicles inside the needle,thus facilitating the automation of transferring follicles from extraction to implantation.Then a visual feedback system is proposed to accurately position the follicles during the transplantation.The experimental results show that average distance deviation between the actual and target positions is 0.6128 mm and the average deviation of hair implantation depth is 1.7176 mm,which verify the feasibility of the proposed system.

微细窄通道内纳米线表面的过冷沸腾流动与传热特性

微/纳米结构表面对流动沸腾过程有着显著影响,被应用于高热流的设备散热中.为了进一步探究其物理规律,以去离子水为工质,配合高速摄像观测,研究了截面为0.5 mm×5 mm的矩形微细窄通道内纳米线表面的竖直流动过冷沸腾.一种TiC纳米线的直径约230 nm,高度约4μm;另一种直径约535 nm,高度约12μm.过冷沸腾的质量流量是200和300 kg/(m^2s),过冷度为10 K,热流密度范围是20~200 kW/m^2.分析了不同工况下过冷沸腾的沸腾曲线、平均换热系数和两相流流型.研究发现, 4μm高度纳米线表面的两相换热系数更高,但高热流条件下传热恶化更早. 4μm高度纳米线表面形成了"形成拉长气泡——气泡上下游扩张——局部干涸——流体重新润湿"的周期性两相流型,而12μm高度纳米线表面的流型在高热流下仍以气泡聚合以及形成受限拉长气泡向下游扩张为主.

LNG接收站用低温球阀阀座唇形密封圈接触特性分析

低温球阀是液化天然气(LNG)接收站中必不可少的流体管道控制装置之一,其在低温工况下工作时阀座密封易发生泄露,严重威胁工业生产的正常运行。本工作基于热固耦合方法研究了LNG接收站用低温球阀唇形密封圈与阀体和阀座的接触特性,包括接触间隙和接触压力。结果表明,受低温介质的影响,唇形密封圈上存在较大温差,导致密封圈上的Mises应力大幅增加,最大Mises应力达到204.92 MPa。相比于常温工况时,低温工况时唇形密封圈的接触间隙变大,接触压力减小,最大接触间隙值达到-0.72 mm。增大弹簧预紧力在一定程度上可以改善低温工况时唇形密封圈的密封性能,增大接触压力。本工作对低温球阀的阀座密封设计和研究具有一定参考价值。