Design of low-alloying and high-performance solid solution-strengthened copper alloys with element substitution for sustainable development

Solid solution-strengthened copper alloys have the advantages of a simple composition and manufacturing process,high mechanical and electrical comprehensive performances,and low cost;thus,they are widely used in high-speed rail contact wires,electronic component connectors,and other devices.Overcoming the contradiction between low alloying and high performance is an important challenge in the development of solid solution-strengthened copper alloys.Taking the typical solid solution-strengthened alloy Cu-4Zn-1Sn as the research object,we proposed using the element In to replace Zn and Sn to achieve low alloying in this work.Two new alloys,Cu-1.5Zn-1Sn-0.4In and Cu-1.5Zn-0.9Sn-0.6In,were designed and prepared.The total weight percentage content of alloying elements decreased by 43%and 41%,respectively,while the product of ultimate tensile strength(UTS)and electrical conductivity(EC)of the annealed state increased by 14%and 15%.After cold rolling with a 90%reduction,the UTS of the two new alloys reached 576 and 627MPa,respectively,the EC was 44.9%IACS and 42.0%IACS,and the product of UTS and EC(UTS×EC)was 97%and 99%higher than that of the annealed state alloy.The dislocations proliferated greatly in cold-rolled alloys,and the strengthening effects of dislocations reached 332 and 356 MPa,respectively,which is the main reason for the considerable improvement in mechanical properties.

An Immune-Inspired Approach with Interval Allocation in Solving Multimodal Multi-Objective Optimization Problems with Local Pareto Sets

In practical engineering,multi-objective optimization often encounters situations where multiple Pareto sets(PS)in the decision space correspond to the same Pareto front(PF)in the objective space,known as Multi-Modal Multi-Objective Optimization Problems(MMOP).Locating multiple equivalent global PSs poses a significant challenge in real-world applications,especially considering the existence of local PSs.Effectively identifying and locating both global and local PSs is a major challenge.To tackle this issue,we introduce an immune-inspired reproduction strategy designed to produce more offspring in less crowded,promising regions and regulate the number of offspring in areas that have been thoroughly explored.This approach achieves a balanced trade-off between exploration and exploitation.Furthermore,we present an interval allocation strategy that adaptively assigns fitness levels to each antibody.This strategy ensures a broader survival margin for solutions in their initial stages and progressively amplifies the differences in individual fitness values as the population matures,thus fostering better population convergence.Additionally,we incorporate a multi-population mechanism that precisely manages each subpopulation through the interval allocation strategy,ensuring the preservation of both global and local PSs.Experimental results on 21 test problems,encompassing both global and local PSs,are compared with eight state-of-the-art multimodal multi-objective optimization algorithms.The results demonstrate the effectiveness of our proposed algorithm in simultaneously identifying global Pareto sets and locally high-quality PSs.

Boron doped graphdiyne:A metal-free peroxidase mimetic nanozyme for antibacterial application

The abuse of conventional antibiotics leads to increasing bacterial resistance.Nanozyme is a new kind of ultra-efficient and safe nanomaterial with intrinsic enzyme-like activities,showing remarkable potential as a next generation nanobactericide.Graphdiyne(GDY)is a burgeoning two-dimensional(2D)carbon allotrope with intriguing physicochemical properties,holding a great promise as a metal-free nanozyme.In this study,a boron doped GDY nanosheet(B-GDY)was constructed to simulate the performance of peroxidase(POD).By promoting the decomposition of H_(2)O_(2) to produce reactive oxygen species(ROS),the bactericidal efficacies against both Gram-positive and Gram-negative bacteria were substantially enhanced attributed to the extremely high catalytic activity of B-GDY.In-depth density functional theory(DFT)calculations illuminate that doping of boron can introduce more active B-defect sites as well as lower Gibbs free energy during the H_(2)O_(2) decomposition reaction.Notably,B-GDY contributes to significant wound healing and excellent biocompatibility,reducing the biological burden.The design of this nanozyme opens a new avenue for the development of alternative antibiotics.

Optically modulated dual-mode memristor arrays based on core-shell CsPbBr_(3)@graphdiyne nanocrystals for fully memristive neuromorphic computing hardware

Artificial synapses and neurons are crucial milestones for neuromorphic computing hardware,and memristors with resistive and threshold switching characteristics are regarded as the most promising candidates for the construction of hardware neural networks.However,most of the memristors can only operate in one mode,that is,resistive switching or threshold switching,and distinct memristors are required to construct fully memristive neuromorphic computing hardware,making it more complex for the fabrication and integration of the hardware.Herein,we propose a flexible dual-mode memristor array based on core–shell CsPbBr3@graphdiyne nanocrystals,which features a 100%transition yield,small cycle-to-cycle and device-to-device variability,excellent flexibility,and environmental stability.Based on this dual-mode memristor,homo-material-based fully memristive neuromorphic computing hardware—a power-free artificial nociceptive signal processing system and a spiking neural network—are constructed for the first time.Our dual-mode memristors greatly simplify the fabrication and integration of fully memristive neuromorphic systems.

石墨炔负载金属原子催化剂研究进展

金属原子催化剂实现了原子百分之百利用率,具有高选择性和高活性等特点.但由于单个原子表面能大,容易团聚成纳米颗粒,稳定金属原子催化剂的制备对基底提出了较高的要求.石墨炔的特殊结构使其成为一种潜在的金属原子催化剂载体.石墨炔是一种由sp^2和sp杂化碳原子共同组成的新型碳的同素异形体.由于碳碳三键具有线性、无顺反异构和高共轭性等优点,使得石墨炔具有类似石墨烯的二维平面结构,同时具有高导电性、高比表面积、结构稳定等优异性质.石墨炔结构中的sp杂化碳原子能与金属原子形成强的共价键,从而使金属单原子能稳定存在石墨炔结构中;因此石墨炔是一种理想的金属原子催化剂载体.本文从石墨炔负载金属原子催化剂的结构出发,论述了石墨炔负载金属原子催化剂的研究进展,包括石墨炔负载金属原子催化剂的结构、制备方法、表征手段,重点论述了石墨炔负载金属原子催化剂在电化学催化领域的理论和实验进展.实验证明石墨炔负载的贵金属(Pt和Pd)原子催化剂以及过渡金属原子(Ni和Fe)催化剂都具有优异的电化学催化活性和循环使用性能.

High NO_2/NO_X emissions downstream of the catalytic diesel particulate filter:An influencing factor study

Diesel vehicles are responsible for most of the traffic-related nitrogen oxide（NO x） emissions,including nitric oxide（NO） and nitrogen dioxide（NO2）. The use of after-treatment devices increases the risk of high NO2/NO x emissions from diesel engines. In order to investigate the factors influencing NO2/NO x emissions, an emission experiment was carried out on a high pressure common-rail, turbocharged diesel engine with a catalytic diesel particulate filter（CDPF）. NO2 was measured by a non-dispersive ultraviolet analyzer with raw exhaust sampling. The experimental results show that the NO2/NO x ratios downstream of the CDPF range around 20%–83%, which are significantly higher than those upstream of the CDPF. The exhaust temperature is a decisive factor influencing the NO2/NO x emissions. The maximum NO2/NO x emission appears at the exhaust temperature of 350°C. The space velocity,engine-out PM/NO x ratio（mass based） and CO conversion ratio are secondary factors. At a constant exhaust temperature, the NO2/NO x emissions decreased with increasing space velocity and engine-out PM/NO x ratio. When the CO conversion ratios range from 80% to 90%,the NO2/NO x emissions remain at a high level.

Characterization of material mechanical properties using strain correlation method combined with virtual fields method

The isotropic and anisotropic behaviors are considered as the important formats of the constitutive behaviors,and can also be called the global properties.To improve the identification ability of virtual fields method(VFM)when the global properties are unknown,this paper proposes the strain correlation method(SCM)to determine the global properties before the parameter identification using the VFM.Firstly,the basic principle of SCM is described in detail.Then,the feasibility and accuracy of SCM are verified through the numerical experiments based on the three-point bending configuration and the real experiment of polymethyl methacrylate(PMMA).The influence of the additive Gaussian white noise,local errors in the strain fields,and missing data at the specimen edges on the characterization results are evaluated.The results show that the SCM has good noise immunity and lower accuracy requirements for the strain fields.As an application,the mechanical properties of Ti-6A1-4V alloys fabricated by selective laser melting(SLM)are characterized by the SCM.The results show that the alloys are isotropic,and the isotropic VFM is utilized to determine the mechanical parameters.By using the SCM,the accuracy of identification results can be improved for the isotropic or bidirectional reinforced orthotropic materials when using VFM.