具有良好可再生性的新型二氧化硅磁性氧化石墨烯纳米复合材料

Graphene oxide (GO) wrapped Fe₃O₄ nanoparticles (NPs) were prepared by coating the Fe₃O₄ NPs with a SiO₂ layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO₂ coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO₂ on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO₂ layer can effectively induce the GO nanosheets to completely wrap the Fe₃O₄ NPs, forming a core-shell Fe₃O₄@SiO₂@GO composite where Fe₃O₄@SiO₂ NPs are firmly encapsulated by GO nanosheets. The optimized Fe₃O₄@SiO₂@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.     

微波预处理对复杂铜矿磨矿及浮选动力学的影响

The effect of CaCO₃, Na₂CO₃, and CaF₂ on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe₃PO₇ and apatite was investigated. The results revealed that Na₂CO₃ had the most significant effect on iron recovery and dephosphorization, followed by CaCO₃, the effect of CaF₂ was negligible. The mechanisms of CaCO₃, Na₂CO₃, and CaF₂ were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe₃PO₇ was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO₃ reacted with Fe₃PO₇ to generate an enormous amount of Ca₃(PO₄)₂ and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na₂CO₃, the phosphorus in Fe₃PO₇ migrated to nepheline and Na₂CO₃ improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF₂ reacted with Fe₃PO₇ to form fine Ca₃(PO₄)₂ particles scattered around the iron particles, making the separation of iron and phosphorus difficult.     

不同硅饱和系数水榴石的碳酸化分解动力学

Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.     

一种超重力燃烧合成制备高性能高熵合金的新方法

A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr_0.9FeNi_2.5V_0.2Al_0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.     

利用皮秒激光烧蚀制备非球形铝纳米颗粒

We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl₃) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.     

窄板坯结晶器内连铸工艺参数对钢液流场的影响

Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.     

电渣重熔脱硫技术研究进展

Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.     

Mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during high-temperature sintering

The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al₂O₃?Na₂O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na₄Ca₃(AlO₂)₁₀ was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na₄Ca₃(AlO₂)₁₀, CaO·Al₂O₃, and 12CaO·7Al₂O₃, and the content of Na₄Ca₃(AlO₂)₁₀ could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na₄Ca₃(AlO₂)₁₀ occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na₄Ca₃(AlO₂)₁₀ was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na₄Ca₃(AlO₂)₁₀ was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.     

含细夹层的分矿充填层中流动特性的可视化

Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.     

经济发展·社会发展·人的发展

发展是经济发展、社会发展和人的发展的统一体;就西方的发展理论来看,人们对发展的理解经历了一个从经济视角到社会整体视角再到人的视角的转换过程。经济发展、社会发展和人的发展是构成发展内涵的三个基本方面,它们之间既相互区别又相互联系;要树立和落实科学发展观,就必须正确认识和处理它们之间的辩证关系。     

地方青少年发展基金会发展研究

对地方青少年发展基金会面临的挑战和现状进行分析,认为地方青少年发展基金会是一类较为特殊的基金会群体,社会转型对地方青少年发展基金会来说,挑战大于机遇。提出了具有很强现实针对性和应用性的战略选择和现实路径。     

无铅易切削黄铜的发展现状及发展方向

叙述了国内外无铅易切削黄铜的发展和研究现状,对以其他更环保的元素替代铅的研究进行了讨论,从切削性、力学性能、热锻性和耐腐蚀性能方面总结了新型易切削黄铜的优缺点。对当前已经应用的无铅黄铜,特别是铋黄铜存在的问题进行了总结,提出了铋黄铜改性的研究方法以及发展方向。     

可持续发展与西部大开发

可持续发展强调发展的持续性、公平性、整体性和共同性，是人类发展观的重大变革。西部地区位于我国大江大河上游，是全国重要的生态屏障。但这里水土流失严重、沙漠化迅速扩展、环境污染严重，致使生命环境更加脆弱，形势十分严峻。鉴于此，西部大开发必须走可持续发展的道路；要树立资源和环境有限的思想；因地制宜、因害设防，加快实施山川秀美工程；搞好环境污染治理；加强法制建设，依法保护生态环境；增加投入，合理使用资金，使西部生态环境建设取得良好效果。     

汽车开发中的虚拟产品开发技术

首先论述了虚拟产品开发技术产生的背景、内涵及功能特点 ,其次重点介绍了虚拟产品开发技术在汽车开发中的应用技术及进展 ,包括 :虚拟油泥建模 ,虚拟概念车的总体评价 ,汽车车身室内的虚拟人体工程学设计 ,虚拟风洞技术 ,汽车碰撞的虚拟仿真 ,整车性能的虚拟仿真与评价 ,虚拟装配与干涉评价等     

基于产品开发域的产品开发方法

产品开发既是企业经营管理的核心，也是决定企业兴衰成败的关键，引起了越来越多的企业的重视。同时产品开发是一个集成和交互的过程，作者从产品开发所涉及到的产品、组织和流程的角度出发，指出产品开发中存在三个域，即：产品域、组织域和流程域。并指出产品域是三个域的核心，建立了三个域之间的交互关系。在此基础上，提出了产品域中产品零部件的分类方法，并根据三个域之间的交互关系，建立了相应的组织域和流程域，然后指出了产品域中产品零部件管理的发展方向，还给出了此方法在一家摩托车制造厂的应用实例。     

旅顺国家级经济开发区生态旅游开发研究

系统分析了旅顺开发区的生态旅游资源,包括:山地资源、海滨资源、岛屿资源、温泉资源、气候资源、生物资源等几个方面。同时,通过区位条件、区域交通、客源市场、区域经济、发展机遇等几个方面对旅顺开发区开展生态旅游的可行性进行了探讨。基于国内外的成功经验,结合旅顺开发区的实际情况,对区域开展生态旅游提出了相应对策。     

论环境发展的几个问题

环境发展已成为全球的热门话题，它关系到可持续发展能否实现，正确认识环境发展的重要性和迫切性，能促使我们探寻环境发展的有效途径。本文首先分析了环境发展的重要性，接着析了环境发展的迫切性，最后提出了环境发展的途径。     

人力资源开发与经济可持续发展

人力资源开发是经济可持续发展的前提和基础 ,我国经济要实现可持续发展 ,必须重视人力资源开发。我国人力资源开发的措施 :一是加大对人力资本投资 ,提高人口的整体素质 ;二是提高人力资本的使用效率 ;三是优化人力资源的配置结构 ,促进产业结构的调整     

埋入式进气道的技术现状

介绍了埋入式进气道的设计方法、气动性能及流场控制等的研究现状 ,对该领域存在的问题进行了分析并探讨了埋入式进气道的研究方向和研究方法