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.     

CAEP-FEL装置自发辐射和同步辐射分析

在自由电子激光振荡器中，电子在摇摆器产生的自发辐射与在偏转轨道上产生的同步辐射同时存在，自发辐射是与受激辐射密切相关的过程。分析对比了同步辐射与自发辐射的强度和频谱分布，并与实验结果进行了比较。     

基于同步辐射的紫外-真空紫外光谱辐射测量装置的研制

研究基于同步辐射的紫外-真空紫外光谱辐射测量装置. 通过切换前置镜位置来完成同步辐射光源和传递标准光源的测量. 讨论了辐射计偏振特性对测量结果的影响. 根据Schwinger提出的理论公式,利用同步辐射作为基准辐射源,在115～350nm的波长范围测量了作为传递标准的氘灯的光谱辐射亮度,测量不确定度为11%～14%.     

同步辐射技术及其应用

介绍了同步辐射光的产生、发展及其基本特性,概述了同步辐射技术在医学、环境和工业等领域的应用及目前的技术动向和今后的发展趋势.     

中国高能同步辐射光源及其验证装置工程

同步辐射光源已成为众多学科前沿领域不可或缺的大科学装置.我国现有的同步辐射光源都是中、低能光源,然而与国家重大需求和工业核心创新能力相关的研究急需高性能的高能同步辐射光源支撑,因而建设一台高性能的高能同步辐射光源将为国家的重大需求提供重要支撑,并大大缩小我国与国际先进光源的差距.本文阐述了建设高能同步辐射光源的必要性及意义,分析了国内外同步辐射装置的发展现状,重点介绍了中国高能同步辐射光源的科学目标、初步方案和技术难点,并系统介绍了国家"十二五"重大科研基础设施发展规划中拟开展的高能同步辐射光源验证装置工程的建设目标和建设方案.     

喷流内粒子同步加速辐射数值解研究

同步加速辐射是活动星系核低能辐射的主要辐射机制。研究喷流内粒子的同步加速辐射过程对认识活动星系核内部辐射机制,能谱分布、光变时标等热点问题非常重要。文章研究活动星系核喷流内粒子的同步辐射过程,用数值的方法得到喷流内粒子的同步辐射谱分布情况,用得到的粒子谱分布计算了BL Lac天体PKS 2155-304低能辐射。结果表明,PKS 2155-304低能辐射能用同步辐射很好地解释。     

一种新的低成本微电子机械系统微针加工方法

提出了一种新的空心微针阵列加工方法，利用三次同步辐射曝光和显影过程来加工微针．通过无掩膜曝光实现显影腐蚀的侧向扩展，从而获得微针的尖部形状；为克服因同步辐射光源的光束为近似椭圆高斯分布所造成的微针呈椭圆形及微针在各个方向上的强度不均匀问题，采用正交两次曝光方法来补偿同步辐射光源的光束分布不均匀性．这种方法工艺过程非常简单，并且无需任何特殊装置．文中所有实验是在日本立命馆大学的超导压缩存储环同步辐射光源AURORA的第13条线上完成的．实验结果表明，利用这种新方法可以非常方便地加工出高质量的空心微针，实现微针阵列的低成本、批量化制造．     

聚合物核壳结构微球的同步辐射显微表征研究

针对聚合物核壳结构微球的结构特点,引入了同步辐射显微技术对微球的结构和组分进行了初步研究.利用同步辐射X射线显微成像技术对微球的内部形貌进行了表征,观测到壳层内壁大多呈光滑的圆弧,也有局部由若干个小圆弧连接组成;利用同步辐射红外显微光谱法对核内物质的组分进行了研究,结合X射线显微成像技术观察到的微球壳层内壁的高吸收现象,初步验证了微球内铁离子在辐照下被还原的化学反应过程,表明了利用聚合物核壳结构微球来开展化学反应研究是可行的.     

SSRF前端光子挡光器的结构设计和热应力分析

光子挡光器是同步辐射光束线前端区的重要部件,其主要作用是阻挡高强度同步辐射.利用有限元分析软件ANSYS,对上海同步辐射装置(SSRF)前端光子挡光器,进行了精细的温度和热应力分析.分析结果表明,新设计的光子挡光器热应力水平有了显著的降低,提高了光子挡光器承受热负载的能力,满足SSRF前端部件的设计要求.     

北京正负电子对撞机及其重大改造工程

北京正负电子对撞机（BEPC）自1988年建成投入运行以来，在高能物理实验和同步辐射研究领域做出了许多重要成果，成为在其工作能区性能国际领先的高能加速器。为了在激烈的国际竞争中继续保持我国在一粲物理领域的领先地位，我国科学家提出了北京正负电子对撞机重大改造计划（BEPCII），于2003年底得到国家批冷谈淮。和BEPC一样，BEPCII“一机两用”用于高能物理和同步辐射研究，用为对撞机的主要指标的亮度将比BEPC高100倍，同步辐射的性能也将大幅度提高。简要报告了BEPC上的研究成果、BEPCII工程建设的进展及其发展前景。     

Blazar喷流中相对论电子的同步辐射过程

对于Blazar的相对论喷流,假设其中存在一个球形区域,相对论电子在该区域内在磁场的作用下将产生同步辐射。先对其发射系数和吸收系数等进行了计算,然后对它们与磁场和频率等的关系进行分析,并对同步辐射谱加以讨论。