Enhanced Photocatalytic Activity of Nanoparticle-Aggregated Ag–AgX(X=Cl, Br)@TiO_2 Microspheres Under Visible Light

Ag–AgX(X = Cl, Br)@TiO_2 nanoparticle-aggregated spheres with different mass ratio of R = TiO2/Ag(X) from 35:1 to 5:1 were synthesized by a facile sol–gel technique with post-photoreduction. The photocatalytic activities of both Ag–Ag Cl@TiO_2 and Ag–Ag Br@TiO_2 under visible light are effectively improved by ~3 times relative to TiO_2 NPAS under the simulated sunlight for the decomposition of methyl orange(MO). Ag–AgBr@TiO_2 showed 30% improvement and less stable in photocatalytic activity than that of AgCl@TiO_2. The role of Ag and Ag X nanoparticles on the surface of Ag–Ag X(X = Cl,Br)@TiO_2 was discussed. Ag on these samples not onlycan efficiently harvest visible light especially for Ag Cl, but also efficiently separate excited electrons and holes via the fast electron transfer from Ag X(X = Cl, Br) to metal Ag nanoparticles and then to TiO_2-aggregated spheres on the surface of heterostructure. On the basis of their efficient and stable photocatalytic activities under visible-light irradiation, these photocatalysts could be widely used for degradation of organic pollutants in aqueous solution.

聚己内酰胺微孔注塑发泡:纳米成核剂的影响

将几种纳米成核剂分别与线型PA6(L-PA6)和长链支化PA6(LCB-PA6)共混制得纳米复合材料。通过流变行为表征发现,纳米成核剂对于L-PA6的流变行为影响不大,但显著提高了LCB-PA6的熔体强度;通过非等温结晶动力学表征发现,纳米石墨与碳纳米管可有效提高PA6的结晶速率和结晶温度;通过泡孔形貌表征发现,加入纳米石墨对L-PA6的发泡性能提升最大,250℃的泡孔密度为1.66×10^(7) cm-3,达到L-PA6纯树脂的3倍以上,加入碳纳米管对LCB-PA6的异相成核效果最好,且可有效降低LCB-PA6对发泡温度的依赖性;通过力学性能测试发现,碳管与LCB-PA6的界面结合力较低导致LCB-PA6成核改性发泡材料表现出较低的拉伸模量与弯曲模量;而羧基化碳纳米管由于表面羟基的极性,增大了其与LCB-PA6的界面结合力,显著提高了LCB-PA6的拉伸模量与弯曲模量;纳米石墨由于其高强度层状结构,对L-PA6的拉伸模量与弯曲模量提升巨大。

Dynamic transfer model and applications of a penetrating projectile‐fuze multibody system

In modern warfare,fortifications are being placed deeper underground and with increased mechanical strength,placing higher demands on the target speed of the penetrating munitions that attack them.In such practical scenarios,penetrating fuze inevitably experience extreme mechanical loads with long pulse durations and high shock strengths.Experimental results indicate that their shock accelerations can even exceed those of the projectile by several times.However,due to the unclear understanding of the dynamic transfer mechanism of the penetrating fuze system under such extreme mechanical conditions,there is still a lack of effective methods to accurately estimate and design protection against the impact loads on the penetrating fuze.This paper focuses on the dynamic response of penetrating munitions and fuzes under high impact,establishing a nonlinear dynamic transfer model for penetrating fuze systems,which can calculate the sensor overload signal of the fuze location.The results show that the relative error between the peak acceleration obtained by the proposed multibody dynamic transfer model and that obtained by experimental tests is only 15.7%,which is much lower than the 26.4%error between finite element simulations and experimental tests.The computational burden of the proposed method mainly lies in the parameter calibration process,which needs to be performed only once for a specific projectile‐fuze system.Once calibrated,the model can rapidly conduct parameter scanning simulations for the projectile mass,target plate strength,and impact velocity with an extremely low computational cost to obtain the response characteristics of the projectile‐fuze system under various operating conditions.This greatly facilitates the practical engineering design of penetrating ammunition fuze.

Low Li ion diffusion barrier on low-crystalline FeOOH nanosheets and high performance of energy storage

To obtain symmetric supercapacitors(SCs)with high energy density,it is critical to fabricate an electrode with wide potential window and excellent capacitive performance.Herein,by using the strong double hydrolysis reaction between anions and cations,the FeOOH nanosheets on the surface of activated carbon cloth(FeOOH@AC)are prepared through a simple hydrothermal process.The FeOOH@AC electrode exhibits maximum capacitance of 4,090 mF·cm^−2 at wider potential window-1–0 V and 3,250 mF·cm^−2 at 0–1 V versus SCE in 2 M LiNO3 electrolyte.With two pieces of FeOOH@AC electrodes the obtained symmetric SC can operate at the voltage window of 2 V.This FeOOH symmetric SC shows high energy density of 13.261 mWh·cm^−3 at a power density of 14.824 mW·cm^−3 and maintains 4.175 mWh·cm^−3 at a maximum power density of 118.564 mW·cm^−3,as well as excellent charge storage capacity and cyclic stability.Li ion adsorption and diffusion mechanism on the(200)facets of FeOOH are explained by the density functional theory(DFT)calculations.The simple synthesis process and excellent capacitance performance of the FeOOH@AC composite make it a very promising candidate for high performance symmetric SC electrodes.

A facile strategy of in-situ anchoring of Co_(3)O_(4) on N doped carbon cloth for an ultrahigh electrochemical performance

Enhancement of supercapacitors(SCs)with high-energy density and high-power density is still a great challenge.In this paper,a facile strategy for in situ anchoring of Co_(3)O_(4) particles on N doped carbon cloth(pCoNCC)is reported.Due to the interaction of the doped N and Co_(3)O_(4),the electrochemical performance improves significantly,reaching 1,940.13 mF·cm^(−2) at 1 mA·cm^(−2) and energy density of 172.46μWh·cm^(−2) at the power density of 400μW·cm^(−2),much larger than that without N doping electrode of 28.5 mF·cm^(−2).An aqueous symmetric supercapacitor(ASSC)assembled by two pCoNCC electrodes achieves a maximum energy density of 447.42μWh·cm^(−2) and a highest power density of 8,000μW·cm^(−2).Utilizing such a high-energy storage ASSC,a digital watch and a temperature-humidity detector are powered for nearly 1 and 2 h,respectively.Moreover,the ASSC displays a superb electrochemical stability of 87.7%retention after 10,000 cycles at 40 mA·cm^(−2).This work would provide a new sight to enhance active materials performance and be beneficial for the future energy storage and supply systems.

Performance Limit Evaluation Strategy for Automated Driving Systems

Efficient detection of performance limits is critical to autonomous driving.As autonomous driving is difficult to be realized under complicated scenarios,an improved genetic algorithm-based evolution test is proposed to accelerate the evaluation of performance limits.It conducts crossover operation at all positions and mutation several times to make the high-quality chromosome exist in candidate offspring easily.Then the normal offspring is selected statistically based on the scenario com-plexity,which is designed to measure the difficulty of realizing autonomous driving through the Analytic Hierarchy Process.The benefits of modified cross/mutation operators on the improvement of scenario complexity are analyzed theoretically.Finally,the effectiveness of improved genetic algorithm-based evolution test is validated after being applied to evaluate the collision avoidance performance of an automatic parallel parking system.