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.     

南京体院体育表演专业学生实践能力调查研究

中共中央国务院《关于深化教育改革全面推进素质教育的决定》中明确指出＂以培养学生创新精神和实践能力为重点＂实施素质教育,因此,培养学生实践能力已成为高校教育的一项重要任务。本研究通过问卷调查法,结合本专业学生的教学实践,对学生实践能力现状进行了全面的调查分析,有助于提高师生思想认识,优化教学,提供并创造更多的实践平台,全面提升学生实现创新能力。     

高职《VB程序设计》实践教学探讨

实践能力和创新精神是高等教育质量的重要内涵。文章介绍了在VB的实践教学中，以加强学生实践能力培养和创新能力的培养为主线，以三个平台为依托，确立了由四个模块组成的实践教学体系，充分调动学生的学习积极性和创造性，提高高职教育教学质量，增强高职学生的就业竞争力。     

以科技竞赛为载体培养工科学生创新能力

创新实践能力是工科学生创新人才培养的重点,鼓励工科学生积极参加科技竞赛是提高他们创新实践能力的有效途径之一.针对工科学生创新能力存在的问题,结合近几年学生参加科技竞赛的实践,分析了科技竞赛活动对提高学生创新实践能力的必要性,并对基于科技竞赛的工科学生创新精神与创新能力培养模式提出了改进措施.     

提高原油采收率,创新实验教学平台建设

培养和提高学生的创新能力和实践动手能力是高等教育的一项重要课题。培养创新型和实践型石油工程人才迫切需要构建大学生创新实验教学平台。从硬环境、软环境、运行模式等方面对石油工程专业提高原油采收率大学生创新实验教学平台建设进行了探讨。实践表明,石油工程专业提高原油采收率创新实验平台为培养学生的创新意识、创新能力和科研兴趣营造了良好的软硬件环境。     

面向实践创新能力培养的数字信号处理实验教学改革

数字信号处理实验教学在培养学生关于数字信号处理的实践能力和创新意识方面有着非常重要的作用。为了提升学生的创新实践能力,从实验内容、教学模式和考核方式3个方面对数字信号处理实验教学进行了改革,采用层次化和多类型的实验内容、基于翻转课堂的教学模式以及侧重过程的多元化考核方式。教学实践的结果表明,学生成为了数字信号处理实验课堂的主角,实践能力和创新意识都得到了显著提高。     

独立学院学生创新实践能力的培养

培养大学生的创新精神与实践能力已经成为高等教育中极为重要的环节,然而在独立学院环境下开展学生创新实践活动存在着诸多问题。天津大学仁爱学院在培养学生创新精神和实践能力方面有自己的实施方略,并已取得阶段性成果。     

计算机专业实践教学方法创新研究

实践教学是高校培养学生创新意识和创新能力的重要环节,计算机专业应注重学生实践动手能力培养,才能培养出大批满足社会需求的创新性人才。然而当前计算机专业实践教学普遍存在观念落后,方法单一僵化等问题。为解决上述问题,论文结合我校计算机专业实践教学,特开展了“交替式学工结合”、“案例项目驱动”、“课程模块化”、“实践理论一体化”等实践教学方法创新研究,对提高计算机专业学生的实践创新能力和择业竞争力具有指导作用。     

基于创新人才培养的实验室建设

实验室是高校培养学生创新能力的重要基地.通过实验室建设.将有力地推进实验教学内容、教学体系、教学方法和教学手段的改革,推进教学质量提高,从而促进学生的实践能力及创新能力的全面提升.     

作物栽培学实践性教学改革

从分析作物栽培学实践教学的现状和存在的问题入手,探讨了作物栽培学教学试验田、实验室教学、课程教学实习、研究型综合型实验、教学实习基地等实践性教学环节的改革,通过改革现行的实践性教学体系、管理体制、教学内容、教学方法与教学手段,逐步将学生的兴趣吸引到实践中来,在实践过程中培养他们观察问题,解决问题的能力,在此基础上,进一步开展创新性、研究性实验,从而提升学生的创新实践思维能力,达到提高学生综合素质的目标。     

计算机专业实践教学体系建设的研究与探索

实践教学对于提高学生工程实践能力和创新能力具有极其重要的作用,是高等教育不可缺少的重要一环。针对社会对于高层次计算机专业人才的巨大需求,以培养学生的实践和创新能力为核心,阐述了加强计算机专业实践教学体系建设的意义和作用。实践证明,建设高水平的实践教学体系能够有效提高学生的工程实践能力和创新能力,对深化计算机专业实践教学改革起到了良好的示范作用。