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.     

水产养殖学专业实验与实习教学结合的实践与思考

实验和实习教学是水产养殖专业人才培养的两个重要环节.该实验率先尝试将水产养殖6门专业课的实验与生产实习教学密切结合的教学方式,解决实验材料与实习基地缺乏、实验实习内容单一陈旧和学生对实验实习不感兴趣的问题,提高学生的理论知识与专业综合素质,实现理论教学向应用教学的转变.文章总结了提高实验教学和生产实习质量的创新改革措施.     

区域地理野外实习绩效评价研究

区域地理野外实习评价不应仅仅局限于指导教师对实习报告的给分评定,而应全面地、动态地评价区域地理野外实习的整个过程.通过阐述区域地理野外实习绩效评价的内涵,提出了教师评价与学生评价相结合、自评与互评相结合、强调动态评价的原则,并简要介绍了区域地理野外实习绩效评价的具体方法.     

文山学院地理专业野外实习成绩评价体系研究

从地理野外实习的意义出发,结合地理实习过程的准备阶段、野外过程和成果总结三个阶段建立了地理野外实习的评价方法和评价指标,共建立了10个考评指标,并对每个指标设立了权重,为合理评价学生的实习成绩提供了标准,有利于提高地理野外实习的效果。     

植物学野外实习教学改革实践与探索

植物学野外实习是《植物学》教学的一个重要组成部分,是生物专业必不可少的实践性环节之一。如何改革植物学野外实习是生物专业共同关注并亟待解决的问题。经过五年的理论探索和教学实践,改革野外实习内容和形式,引导学生主动探索自然界,主动获得植物学知识的能力。野外实习结合科研活动,提高学生科研素质和创新能力,也为提高植物学野外实习教学质量提供参考。     

高等学校地理专业人文地理学野外实习课程建设研究--兼论芜湖市实习基地的建立

目前,野外实习课程建设是人文地理学课程群建设和教学改革中最为薄弱的环节之一.本文提出了人文地理学野外实习教学的指导思想,阐述了人文地理学野外实习的重要意义.以安徽师范大学地理专业人文地理学野外实习教学为例,提出建立芜湖市实习基地,在分析芜湖市区位条件、发展历史、城市建设、经济发展等情况的基础上,尝试性地进行实习教学环节的设计.     

高校毕业实践监管存在的问题及对策

高校目前毕业实践过程中存在较多问题,这是由指导教师和实践主体学生两方面因素引起的,研究分析表明:成立毕业实践督导组,有效监管、严把毕业实践选题质疑、建立指导老师监督机制和奖惩制度、毕业实践创新、建立相应的质量保障体系,实施毕业实践规范化管理等措施能有效克服目前存在的问题。     

田野调查对人类学研究的价值与意义

目前,田野调查由于种种主观和客观因素,发展状况不理想,并由此引起了部分学对其重要性和必要性的质疑。试图从田野调查的数量、质量以及研究自身的主观认知等方面对其价值和意义进行简要评述,从而肯定田野调查对人类学研究的重要价值和意义。     

研究型自然地理实践教学模式探讨

传统的自然地理实践教学模式存在三大问题：一是实验与实习相割裂;二是认识与验证型实验、实习占绝大多数;三是组织模式为：教师讲、学生记笔记、写报告,难以调动学生的积极性。针对以上问题,提出研究型自然地理实践教学模式与组织体系,把实验与实习结合起来;减少验证性实验实习,以问题为导向,将专题研究与实践教学相结合;改变教师单纯讲授的传统教学模式为以学生为主体的研究型实践教学体系,培养和提高学生的实践能力和创新能力。     

阜阳师院体育专业教育实习现状调查与对策研究

运用调查、访谈和观察法对阜阳师院体育教育专业教育实习组织管理现状进行研究,研究表明:教育实习存在的主要问题有学生专业基础不扎实、综合教育能力欠缺、实践能力不强;指导教师对中学教材、教法等情况不熟悉,指导形式化倾向严重,教育实习的管理经验不足,针对性不够,教育实习组织管理存在问题有待进一步制度化、规范化和科学化,针对出现的问题,提出相应的对策。     

对篮球专选班学生裁判能力培养的研究

对篮球专选班学生裁判能力培养是很重要的一环．在教学中通过全面系统地学习篮球竞赛裁判规则和临场裁判工作理论知识，采取了各种不同的策略与方法，培养学生的临场裁判能力，为今后的教学、训练和参加篮球裁判工作奠定了坚实的基础。