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.     

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.     

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.     

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.     

利益表达机制的完善与和谐社会构建

完善的利益表达机制对和谐社会的构建，具有十分重要的作用。我国现阶段的利益表达机制还存在着一些缺陷，如利益表达主体表达意识缺乏、利益表达组织发展不平衡、制度内利益表达渠道不畅通、利益表达机会不均衡、群众性利益表达作用不明显等。必须进一步完善利益表达机制，让社会成员能够通过合法的方式、畅通的渠道和途径平等表达自己正当的利益诉求。     

新农村建设中社区发展研究:基于利益逻辑与社区建设的双重视角

新农村建设可以实现农民利益在时空上拓展、维度上深化、内容序列上优化组合,力求实现利益逻辑与社区建设在时空、组织、制度和文化上的契合.基于农民利益逻辑与农村社区建设的双重视角对新农村社区发展进行机理考量,归结出利益逻辑的三个层次即利益参与、利益发展和利益和谐.通过对社区民主建设、社区经济建设和社区文化建设来构建社区发展的保障机制、动力机制和导向机制体系,实现农村利益主体、利益客体和利益载体的互动共进与和谐发展.     

信阳市城市生活垃圾处理工程效益分析

城市生活垃圾无害化处理工程是一项具有良好的社会效益、环境效益和一定经济 效益的公益工程。本文就信阳市城市生活垃圾无害化处理工程的社会效益、环境效益和经济效益进行了分析，以阐述其建设的必要性和可行性。     

"泛珠三角"区域旅游合作利益探讨

从“泛珠三角”区域概念入手,引出区域旅游合作特点;根据其利益主体的多元性和利益的广泛性,探讨区域旅游合作中的利益冲突,并对此提出建立利益均衡、利益导向、利益分配和利益补偿等机制.     

高新技术园区创业机制形成动力的经济学思考

高新技术园区以高新技术创业为主要方式实现高新技术产业化,促进了区域经济社会的发展。创业社会利益是指高新技术创业活动发生后对社会产生的利益增进,是创业者利益与创业企业利益的外部性表现。高新技术园区政府构建创业机制动力是获得更大的外部性利益,并通过外部性利益内部化的方式推动创业活动的开展。     

儒家义利观及其对煤矿安全生产理念培育的启示

儒家传统文化中的义利观包括义利合一、以义制利、重义轻利等基本思想,社会主义市场经济条件下,我们应汲取儒家传统文化的精华,用正确的义利观引导煤矿企业处理好生产与安全之间的关系,处理好企业经济效益与国家长远利益的关系,培育义利合一的煤矿安全生产理念,保障安全生产工作的顺利进行。     

引进项目效益的评价指标体系建立与综合评价

从技术效益、投资效益、结构效益和宏观效益等四个方面,建立了由14个指标构成的能够全面反应技术引进项目经济效益的综合评价指标体系;采用层次分析法确定了各指标的权重,运用极值法对各指标值进行了规范,并给出了综合评价方法;最后对沈阳市“八五”时期不同引进方式项目经济效益进行了综合评价和分析·评价结果显示:不同引进方式项目的经济效益,无论是单方面效益,还是综合效益,均极不平衡     

船舶绕避热带气旋方案效益评估

为对船舶绕避热带气旋的航行方案进行效益评价,提出船舶绕避热带气旋方案的效益及其评估的概念,给出一种对船舶绕避热带气旋方案效益进行评估的方法.实例计算分析结果表明,应用该方法计算得到的船舶绕避热带气旋效益值和效益系数,可较为直观有效地对船舶绕避热带气旋方案的效益进行评估,可为航运企业绕避TC工作提供参考,提高企业的经济效益.     

对发展图书馆经济的思考

论述了图书馆经济效益的内涵,就市场经济环境下图书馆如何利用现代技术创造经济效益、实现经济效益与社会效益的双赢进行了探讨。     

循环经济模式下政府与企业的委托-代理问题

为了研究政府宏观的循环经济政策和企业的逆向物流战略之间的协调与决策问题,政府通过一定的激励和监督手段来规范企业的环境行为,企业通过努力来获得经济效益和规避环境风险,通过设计二者在信息不对称情况下的委托-代理模型,分析政府和企业如何订立优化合约和政府如何选择有效可行的监督力度．结果表明,信息不对称条件下,企业推行绿色管理模式的努力水平,取决于这种努力能够带来的经济效益、环境效益和环境风险所构成的综合效益与努力成本之间的比值,企业的代理成本取决于努力所带来的企业效益和环境效益的比值．