交变电场作用下黏性射流的稳定性分析

液体射流在静电或交变电场作用下的失稳和破裂问题在许多工业应用中都有涉及.与静电场作用下射流稳定性研究相比,交变电场下射流的稳定性分析研究要少得多.因此,本文采用电场力和黏性力共同修正压强的黏势流模型来描述交变电场作用下漏电介质液体射流的线性不稳定性,主要研究了交变电场、流体电学性质等参数的影响.交变电场作用下射流的毛细不稳定与静电场作用下射流不稳定特性是相似的.在足够强交变电场作用下,参数不稳定主导表面扰动的发展,从而进入共振电雾化模式.参数不稳定会被黏性耗散抑制,甚至随着频率的增加会完全消失.同时,导电电荷(主要取决于流体导电性)的作用与表面电荷是相反的,因此当电荷弛豫时间接近交变电场周期时,参数不稳定会受到强烈的抑制作用.此外,当气动作用足够强时,参数不稳定会被覆盖.

Recycling the spent electronic materials to construct a highperformance Cu_(1.94)S/ZnS heterostructure anode of sodium-ion batteries

Heterostructure engineering by coupling different nanocrystals has received extensive attention because it can enhance the reaction kinetics of the anode of sodium-ion batteries(SIBs).However,constructing high-quality heterostructure anode materials through green and environmentally friendly methods remains a challenge.Herein,we have proposed a simple one-step method by recycling the electronic waste metal materials to synthesize the Cu_(1.94)S/ZnS heterostructure materials.Combined with the experimental analysis and first principle calculations,we find that the synergistic effect of different components in heterostructure structures can significantly enhance the reversible capacity and rate performance of anode materials.Based on the constructed Cu_(1.94)S/ZnS anode,we obtain a superior reversible capacity of 440 mAh·g^(-1) at 100 mA·g^(-1) and 335 mAh·g^(-1) after 3000 cycles at 2000 mA·g^(-1).Our work sheds new light on designing high-rate and capacity anodes for SIBs through the greenness synthesis method.

RuCo alloy nanoparticles embedded within N-doped porous two-dimensional carbon nanosheets:a high-performance hydrogen evolution reaction catalyst

Developing cost-effective electrocatalysts with high activity and stability especially at high current density is of great significance for the large-scale commercial application of electrochemical water splitting to hydrogen production but still remains challenging.Herein,we report an effective confinement pyrolysis strategy to fabricate embedded ruthenium-cobalt nanoclusters supported on N-doped porous two-dimensional carbon nanosheets(RuCo@CN).Markedly,the embedded structure can effectively prevent the migration,agglomeration,and leaching of nanoparticles,thus endowing the RuCo@CN catalyst with high stability.To be exact,high stability with up to 650 h can be achieved at high current density(-500 and-1000 mA·cm^(-2)).Besides,the RuCo@CN catalysts also exhibit highly reactive with low overpotentials of only 11mV at-10 mA·cm^(-2).Density functional theory calculations reveal that the introduction of cobalt reduces the decomposition barrier of H_(2)O for RuCo@CN alloy,thus promoting hydrogen evolution reaction.

Upconversion nanorods anchored metal-organic frameworks via hierarchical and dynamic assembly for synergistic therapy

Heterogeneous materials made of metal-organic frameworks(MOFs)and optically active nanomaterials have attracted intensive interests in recent years due to their distinct physicochemical properties,but controllable fabrication of these materials remains challenging yet.In this work,we report a new strategy to in situ fabricate heterogeneous nanomaterials based on UiO-66-NH2 and upconversion nanorods(UCNRs)via a hierarchical and dynamic assembly process.Core–satellite structured UiO-66-NH2@UCNRs have been successfully fabricated,and the formation mechanism was thoroughly investigated by the combined use of scanning electron microscopy(SEM)and Fourier transform infrared(FTIR)spectroscopy.Our results revealed the involvement of three main stages:supramolecular assembly of UiO-66-NH2 precursors with UCNRs,nucleation and growth of UiO-66-NH2 crystal,and dynamic assembly with UCNRs accompanied by Ostwald ripening.Furthermore,based on the hereditary optical and porous features of the heterogeneous nanomaterials,an enhanced multimodal synergistic anticancer platform has been established by integrating near-infrared(NIR)-triggered photodynamic therapy(PDT)and pH-triggered anticancer drug delivery,as confirmed by cellular experiments.The present study provides a new avenue for developing advanced functional heterogeneous nanomaterials via the hierarchical and dynamic assembly strategy.

Influence of high configuration entropy on damping behaviors of Ti-Zr-Hf-Ni-Co-Cu high entropy alloys

TiNi-based shape memory alloys(SMAs)have been used as damping materials to eliminate noise and mechanical vibration.However,their application is limited by low working temperatures and damping capacity.In this work,two novel Ti-Zr-Hf-Ni-Co-Cu high entropy shape memory alloys(HESMAs)with different transformation temperatures and damping properties were investigated.The results show that Ti_(25)Zr_(8)Hf_(17)Ni_(30)Co_(5)Cu_(15) has superior damping performance arising from martensitic transformation,shape memory effect(thermal cycle at constant load)as well as superelasticity.Compared to traditional TiNi-based SMAs,the as-cast HESMAs exhibit a much higher ultrahigh yield strength(∼2 GPa)and storage modulus(∼50 GPa).The high configuration entropy of the HESMAs with high uneven internal stress and severe lattice distortion is revealed as the underlying mechanisms governing distinctive damping performance.The effects of high configuration entropy and microheterogeneity on the martensitic transforma-tion behavior and damping performance of HESMAs are clarified in this work,which provides a basis for designing alloys with superior damping properties.

Metal–Organic Frameworks-Mediated Assembly of Gold Nanoclusters for Sensing Applications

Gold nanoclusters(AuNCs)are an emerging type of ultrasmall nanomaterials possessing unique physicochemical characteristics.Metal–organic frameworks(MOFs),a singular kind of porous solid and crystalline material,have attracted tremendous attention in recent years.The combination of AuNCs and MOFs can integrate and improve the prominent properties of both components,such as high catalytic activities,tunable optical properties,good biocompatibility,surface functionality and stability,which make the composites of MOFs and AuNCs promising for sensing applications.This review systematically summarizes the recent progress on the sensing of various analytes via MOFs-mediated AuNCs assemblies based on strategies of luminescence sensing,colorimetric sensing,electrochemiluminescence sensing,and electrochemical and photoelectrochemical sensing.A brief outlook regarding the future development of MOFs-mediated AuNCs assemblies for sensing application is presented as well.