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.     

钢琴集体课标准化教学的探讨

传统钢琴课的教学模式到今天的集体课教学模式的转变,是高师钢琴教学改革的教学成果。重视教学改革的学术经验,将钢琴集体课教学按照标准化教学的要求细化课程内容设置,精心选定教学教材,制定标准化的考核路径,通过具体的教学实践,以期得到客观的、科学的教学效果评价,从而在钢琴集体课教学中实施标准化教学,为提高教学效率提出有效的教学方法。     

高等学校实验教学质量监控点的研究

实验教学在高等学校人才培养中具有重要地位和作用，实施监控是保证人才质量的有效措施。阐述了实验教学质量监控点的概念和功能，设置了包括实验教学理念、实验教学体系、实验教学方法、实验教学考试、实验教学队伍、实验教学信息平台、实验教学开放、实验教学管理制度、实验教学评估、实验教学投入等10个监控点，研究了实验教学监控点内涵及其实践效果。     

视频教学在肩周炎推拿教学中的应用

视频教学作为一种有效的辅助教学手段在医学教学中得到了相当广泛的应用。本文通过分析肩周炎推拿教学的特点,比较传统教学和视频教学优劣势,在教学的实践中探索和总结视频教学在肩周炎推拿教学中的应用优势,并且提出教学视频课件的具体制作要求,提出视频教学与传统推拿教学紧密结合的必要性。     

高校实施专题教学的基本理念和利弊评析

专题教学是大学教学方式改革的一种有益探索和尝试;专题教学有其特定的适用范围,并不是所有的课程都适合专题教学;实施专题教学应遵循四个基本的教学理念;专题教学与传统的教学方式相比,更加有利于促进教学过程中"教"与"学"这两个方面的良性互动和有机统一,进而有利于提高教学质量和效果。     

论高校公共体育课教学评价的程序

高校公共体育课教学评价是对高校体育教学过程、效果、质量和结果的科学测量.制定和遵循科学的评价程序是开展体育教学评价活动的必要条件,只有按照科学的评价程序开展的公共体育课教学评价活动才能客观真实地反应教学情况,从而有利于科学地修订教学计划、适时地改进教学方法、及时地调整教学内容、更好地改进和加强教学工作.详尽论述公共体育课教学评价的一般程序,旨在为高校科学地开展公共体育课教学评价活动提供参考.     

PBL 模式用于工程训练教学的重要意义简

PBL作为一种新型教学模式,在工程训练教学的应用,不是单纯意义上教学方法的改变,而是在教学理念、教学形式、教学组织过程、教学效果等方面对传统教学模式的彻底转变,是站在人才培养的战略高度和从社会发展的需要出发而采用的一种教学实践。采用该教学模式进行工程训练教学,有利于实现工程训练教学目标,有利于提高指导教师各种素质和能力,有利于充分利用和开发各类教学资源,有利于促进工程训练教学改革与发展。文中从上述几个方面,阐述了PBL教学模式应用于工程训练教学的重要意义。     

大学英语教学改革探析

根据大学英语教学现状及其存在的问题,我们从教学观念、教学模式、教学方法、教学手段几方面探讨教学改革的途径,目的在于形成大学英语教学的全新思想,促进大学英语教学的深入改革。     

科学编制实验教学大纲的实践和探索

实验教学大纲属于教学计划的重要组成部分,是高等学校实施实验教学管理的最基本的教学文件,是组织和实施实验教学过程中所必须遵循的依据,也是编写实验教材、指导书,组织实施实验教学和实验教学质量评估的依据,是审定实验项目、编制实验室建设计划和实验室资源合理配置的重要依据。文中结合华南师范大学在修订实验教学大纲中取得的经验,分析了目前高等院校实验教学大纲存在的问题,介绍了科学编制实验教学大纲的经验和做法。     

论大学英语教学中的文化教学

文化教学是英语教学不可缺少的组成部分,在大学英语教学中导入文化教学势在必行。本文从四个方面论述文化教学在大学英语教学中的重要作用,并探讨教师在文化教学中的作用。     

谈体育教学组织、教法的选择与运用

体育教学组织、教法的选择与运用对提高教学质量，增强学生体质起着至关重要的作用。从构成体育教学组织和教法的理论基础，树立科学的教学思想，克服体育教学组织和教法的单一化倾向，提供多种体育教学组织和教法的互相融合以及学生的心理发展规律等方面进行分析，力求为教学研究提供一些理论依据。