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.     

藩部经略与直省支撑——四川在清朝治理西藏中的地位和作用

清前期,清朝逐步实现了大一统,并形成了"直省-藩部"二元并存的疆域结构。彼时,无论是直省地区还是藩部地带,皆是清朝的领土。在清朝统一和治理西藏的过程中,地处直省边缘、同西藏接壤的四川地区,成为清朝经略西藏的依托,在军事支撑、行政支援、后勤保障、交通联络等方面发挥了重要的作用,体现了大一统王朝下直省和藩部之间的相互依存。同时,通过对清代二元并存疆域结构及四川在西藏经略中作用的分析,可以总结出清朝治理西藏的经验和得失。     

从萍乡哥老会起义看清政府的危机应对

萍乡哥老会起义历时二十多天,震惊朝野,后来被清政府残酷镇压,但在镇压过程中却暴露出清政府在应对危机时的种种不足与缺陷,这集中表现在三个方面:一、政府权势的衰微;二、政府重视不足、防范不力;三、地方政府横向合作协调机制缺失。总之,面对萍乡哥老会起义,清政府在处理危机时存在诸多问题。二百多年的大清王朝最终走向灭亡,上述因素值得深思。     

论清代贵州社学的发展与衰亡

清代前期，清政府曾沿袭明朝的地方教育体系，在贵州的广大城乡建立了社学，但由于清统治集团推行阶级压迫和民族压迫政策，乾隆年间宣布裁革贵州境内的所有社学，社学从此走向衰亡。     

清末新军的知识化与新军的背离

新军的最终背离与新军知识化程度的加深有着密切关系。正是由于大量知识分子的加入,新军官兵具有一定的文化基础,便利了资产阶级革命党人在新军中的宣传鼓动;随着新军官兵知识水平的提高,他们对社会状况和清政府的统治会产生更多的思考和怀疑,从而加速了与清政府离心离德的进程,而转向反清的革命阵营,成为清王朝统治的对立方。     

晚清民法近代化论略

1911年，清政府颁布了《大清民律草案》，这是中国历史上的第一部民法典，它揭开了中国民法近代化的序幕。本文主要对晚清民法改革的背景、《大清民律草案》的主要内容、历史意义及局限性等问题进行一番剖析。     

论汉末魏初人物评价标准的新变--以荐举文为中心

汉末魏初，荐举文书中的人物评价标准经过西汉对士人忠与谋的重视，东汉对士人自身秉性的认可而发展成为对士人清名的推崇。“清”成为汉魏易代之际士林人物品评的核心关键词。这种集中体现其时士人理想人格之“清”在承袭士人清白品性的传统意义之外，更增添了士人在乱世中激浊、厉俗的新内涵。汉末魏初士人思想的更新是“清”评形成的基础，而统治者对德高望重且清虚自守的士人的需求与召唤又加速了“清”评的形成。     

试述清代歌本文献的特征

清代歌本文献是清代歌曲发展的真实记载。通过归纳,说明清代现存歌本文献具有数量繁多与类型多样特点,并分析其成困。重点阐述清代歌本文献在继承历代歌本基础上的发展与创新的具体表现,为今人了解和研究清代歌唱音乐提供可靠的依据和有效帮助。     

清代前期推行藏传佛教与对蒙藏的治策

文章探讨了清代前期推行藏传佛教治策的形成、发展和影响,着重论述了“康乾盛世”的清朝皇帝对这一治策的运用,清初推行这一治策,主要是通过打蒙藏上层的牌取得成果的,清代册封达赖喇嘛的策略,即体现出清朝政府有效管理西藏的一项重要制度“。兴黄教以安众蒙古也!”清初藏传佛教治策对于怀柔蒙古产生了历史的影响。     

王树民与清代学术史研究

王树民以考证为基础,对清代学术史的诸多问题提出了独到的见解。他编校整理了一些清代学者的文集,撰写了多篇有关清代学者学术思想研究的论文。此外,王树民纵论清代学术发展之大势,他认为清代学术是以经学为主而以史学为从的经史之学,肯定了乾嘉学者的研究方法。王树民还实事求是地评价了晚清今文学派在政治、学术方面的影响。     

式述清代散见歌曲文献及特征

指出清代除了专集歌曲文献外，还有一部分歌曲散见于类书、乐书、乐谱及宗教典籍中，通过归纳这些歌曲内容，并与前代作品比较，分析出清代不同书谱中所收录歌曲作品在数量、内容、辑录思想上的具体特征，研究这些散见歌曲文献能给清代歌曲文献作重要补充，为今人了解研究清代歌唱音乐提供可靠依据和有效帮助。