Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

To reveal the resonance suppression mechanism of the blood circulation in dragonfly wings,a numerical modeling method of dragonfly wings based on Voronoi diagrams is proposed,and the changes in mass,aerodynamic damping,and natural frequencies caused by blood circulation in veins are investigated.The equivalent mass of blood,boundary conditions,and aerodynamic damping are calculated theoretically.Modal analysis and harmonic response analysis of wing models with different blood circulation paths are performed using the finite-element method(FEM).The vibration reduction ratioδis introduced to compare the damping efficiency of different mass regions.Finally,a natural frequency testing device is constructed to measure the natural frequencies of dragonfly wings.The results indicate that the shape,mass,and natural frequencies of the dragonfly wing model constructed by numerical method agree well with reality.The mass distribution on the wing can be altered by blood circulation,thereby adjusting the natural frequencies and achieving resonance suppression.The highestδof 1.013 is observed in the C region when blood circulates solely in secondary veins,but it is still lower than theδof 1.017 when blood circulates in complete veins.The aerodynamic damping ratio(1.19–1.79%)should not be neglected in the vibration analysis of the beating wing.

石墨烯量子点技术及其照明显示应用

石墨烯量子点(GQDs)作为一种新型的零维材料,由于其独特的物理和化学性质,在LED器件、显示等方面具有广阔的应用前景。本文综述了近年来GQDs自上而下和自下而上的合成方法,总结了GQDs在LED器件以及光子绘画显示中的重要进展。此外,我们理性地分析了GQDs用于照明显示的不足,并预测了GQDs研究的未来发展趋势及其面临的挑战和机遇。

锌掺杂聚吡咯催化乳酸缩合制备高光纯L-丙交酯

聚乳酸作为生物可降解的聚合物材料,有着广泛的应用前景.目前,高质量聚乳酸主要通过丙交酯缩合来制备.其中,丙交酯的光学纯度是影响聚乳酸材料力学性能的关键因素.因此,开发高光纯丙交酯的合成技术,是有着很好应用价值的挑战性课题.在本工作中设计制备了锌掺杂聚吡咯催化剂.该材料可以很好地催化乳酸缩合,合成高光纯丙交酯.值得一提的是,该材料可以多次套用,并保持产物的光学纯度在98%以上.

Ultrafast one-step synthesis of N and Ti^3＋ codoped TiO2 nanosheets via energetic material deflagration

An energetic-material （NAN3） deflagration method for preparing N- and Ti3＋-codoped TiO2 nanosheets （NT-TiO2） was developed. In this method, N radicals filled the crystal lattice, and Na clusters captured partial O from TiO2. The deflagration process was fast and facile and can be completed within 〈 I s after ignition. The obtained NT-TiO2 exhibited rough surfaces with nanopits and nanoholes. The doping concentration can be regulated by controlling the NaN3 addition. The NT-TiO2 samples showed significant enhancements in the visible-light absorption and photoelectric response. The simultaneously produced N radicals and Na clusters from NaN3 deflagration served as N sources and reduction agents, respectively. Additionally, the high deflagration temperature/ pressure improved the reactivity of N radicals and Na dusters. Thus, the present NaN3 deflagration method was demonstrated as an ultrafast and effective approach to fabricate NT-TiO2 with a visible-light response. The proposed NaN3 deflagration method allows the ultrafast synthesis of new functional materials via the efficient deflagration of energetic materials.

Tolerance and acceptance of hepatic venous pressure gradient measurement in cirrhosis(CHESS1904):An international multicenter study

Aim:To determine the tolerance and acceptance of hepatic venous pressure gradient(HVPG)measurements in patients with liver cirrhosis.Methods:This prospective international multicenter study included 271 patients with cirrhosis who were scheduled to undergo HVPG measurement between October 2019 and June 2020.Data related to the tolerance and acceptance of HVPG measurements were collected using descriptive questionnaires.Results:HVPG measurements were technically successful in all 271 patients,with 141(52.0%)undergoing HVPG measurement alone.The complication rate was 0.4%.Postoperative pain was significantly lower than preoperative expected pain(p<0.001)and intraoperative pain(p<0.001),and intraoperative pain was also significantly lower than preoperative expected pain(p=0.036).No,mild,moderate,severe,and intolerable discomfort scores were reported by 36.9%,44.6%,11.1%,6.3%,and 0.4%of these patients,respectively,during HVPG measurement and by 54.6%32.5%,11.4%,1.5%,and 0%,respectively,after HVPG measurement.Of these patients,39.5%had little understanding and 10%had no understanding of the value of HVPG measurement,with 35.1%and 4.1%regarding HVPG measurements as being of little or no help,respectively.Most patients reported that they would definitely(15.5%),probably(46.9%),or possibly(29.9%)choose to undergo additional HVPG measurements again,and 62.7%regarded the cost of the procedure as acceptable.Conclusion:HVPG measurement was safe and well‐tolerated in patients with cirrhosis,but patient education and communication are warranted to improve the acceptance of this procedure.

Planar-symmetry-breaking induced antisymmetric magnetoresistance in van der Waals ferromagnet Fe_(3)GeTe_(2)

Recently discovered magnetic van der Waals(vdW)materials provide an ideal platform to explore low-dimensional magnetism and spin transport.Its vdW interaction nature opens up unprecedented opportunities to build vertically stacked heterostructures with novel properties and functionalities.By engineering the planar structure as an alternative degree of freedom,herein we demonstrate an antisymmetric magnetoresistance(MR)in a vdW Fe_(3)GeTe_(2)flake with a step terrace that breaks the planar symmetry.This antisymmetric MR originates from a sign change of the anomalous Hall effect and the continuity of the current transport near the boundary of magnetic domains at the step edge.A repeatable domain wall due to the unsynchronized magnetization switching is responsible for this sign change.Such interpretation is supported by the observation of field-dependent domain switching,and the step thickness,temperature,and magnetic field orientation dependent MR.This work opens up new opportunities to encode magnetic information by controlling the planar domain structures in vdW magnets.