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.     

心墙堆石坝仓面施工进度动态控制

联合仓面施工进度仿真模型和仓面施工质量实时监控模型,综合考虑施工现场各项影响因素,提出了心墙堆石坝仓面施工进度动态控制模型,通过对仓面施工方案的优化以及对施工过程的施工进度偏差实时分析和反馈,从而实现仓面施工进度的事前、事中控制。将该施工进度动态控制模型应用到某心墙堆石坝,通过对心墙区某仓面进行多方案优化仿真分析,给出仓面施工事前控制推荐优化方案;当实际施工进度滞后时,仓面施工仿真模型根据当前仓面施工面貌进行动态更新并仿真,给出仓面施工事中控制推荐优化方案,从而保障仓面施工进度。应用结果表明,实际施工方案与仿真推荐方案一致,且二者仅相差23 min,实现了仓面施工进度的有效控制。该反馈模型能够及时给出合理的优化施工方案,从而实现对现场施工进度偏差的有效控制,为心墙堆石坝填筑进度提供保障。     

论现代图书馆的文化竞争力建设

从图书馆学术文化的建设、阅读文化的建设、服务文化的建设、礼仪文化的建设、展览文化的建设等方面对文化竞争力建设进行了论述。     

交互式可视化虚拟施工过程技术研究

提出一种交互式可视化虚拟施工方法,以建筑施工验收规范和土木施工技术为判定,依据建立施工数据库将工程项目建设过程中的外在环境构件、建筑构件等固定对象和搬运、吊装、安装、浇筑等施工过程进行全过程仿真建模,实现交互式施工和操作仿真。并根据施工计划和变动动态优化施工方案,提高施工过程效率,有效减少施工风险、优化施工组织、提高工程质量,为企事业单位降低施工成本和风险。     

明确培养目标 规范化学教育教学管理

化学专业的培养目标，是面向21世纪，培养能主动适应社会主义现代化建设和经济建设发展需要的德、智、体、美全面发展的新型复合人才．为实现这一目标，必须深化教学改革，加大专业建设、学科建设、课程建设的力度．笔者就化学专业无机化学课程的建设方面所做的工作做了总结，希望能扬长避短，使课程建设上一个新台阶．     

合福铁路万山隧道出口段浅埋偏压段施工方案优化

在建合福高速铁路安徽段万山隧道,根据施工经验和机械配置,把Ⅴ级围岩的6步CD法开挖施工方法,变更为7步三台阶法.为了确保隧道的施工安全,通过数值试验模拟施工过程,系统分析了该段隧道采用2种不同施工方法的变形稳定性,比较了不同施工方法引起的围岩位移、应力的变化,确定了该段隧道的施工方案,提供了同类隧道施工的借鉴经验.     

浅议建设工程项目造价控制与管理的策略

加强建设工程造价控制与管理,合理确定工程造价,确保工程造价的准确性,是建设工程造价管理的首要任务。从建设项目全过程的角度分析了投资决策、设计、招投标、施工以及竣工各阶段造价控制的方法以及应注意的问题,并通过实际案例说明了科学的造价管理工作对降低建筑项目工程造价的重要作用。     

电气工程专业实验中心建设的实践

以电气工程专业实验中心建设的实践为例,探讨了在新形势下专业实验中心建设的理论和实践,得出了实验室建设应与学科建设、专业建设和实验教学改革相结合的方法,在实验室建设中应加强平台建设、师资队伍建设等措施。     

长春市建设用地扩展与经济增长的协调性研究

长春市的发展处于高速城市化阶段,大规模的开发区建设与产业拉动机制是长春市城市建设用地扩展的主要原因.从长春市建设用地扩展的速度与效率入手,对长春市建设用地扩展与经济增长之间的协调性进行分析.研究结果表明:(1)2001年—2010年长春市建设用地扩展基本满足了经济快速发展的需求,建设用地投入处于报酬递增阶段;(2)建设用地对长春市经济发展的贡献低于资本和技术投入,建设用地节约集约利用水平有待提高;(3)建设用地面积-GDP弹性系数不断上升,建设用地的边际产量开始下降;(4)主要经济指标增长1个百分点所消耗的建设用地过多,城市边缘区出现城市蔓延现象.最后在保障经济发展的前提下,提出抑制城市蔓延的长春市建设用地调控措施.     

浅议福建师范大学学科导航库的建设

在分析福建师范大学学科导航库建设现状和建设环境的基础上,从知识体系结构建设、内容建设、外化建设三方面阐述了学科导航库的建设方案。     

对工程造价监理现状的思考

工程造价管理，就是合理确定和有效控制工程的建造价格。目前，由于工程建设监理无力对工程造价进行控制，施工监理对造价控制的先天不足，以及工程审核、结算不按有关法规、条例执行，动态的工程造价管理至今并未真正形成。工程造价管理的弱化造成了巨大浪费，因此，对工程造价的监理必须引起高度重视。