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.     

面形分割构成论析

本文着重论析了面形分割构成独特的审美性。指出这种构成形式得以成立的关键,是以线分割母面形后,所得五面形必须成为互相依存、牢不可分的,具有符合审美法则的视觉力学关系的整体。提出在作面形分割构成的基本训练中,兼做多种造型表现上的研究与体验的方法。     

新疆野生杏的种下类型

新疆野杏(Armeniaca Vulgaris)是新疆著名的伊犁野果林的主要组成树种之一,新疆野杏林是我国野杏的重要集中地,主要分布在伊犁地区的天山,海拔950～1400米的低山带,与野苹果(Maius sieversii)混交,但也有成片分布.它是荒漠地带山地中出现的“海洋性”阔叶林类型.它也是珍贵的山地“残遗”的古植物群落.作者于1985—1989年参加了《伊犁野果林的综合研究》课题,我们对新源、霍城、巩留等县的几种主要野生果树进行了定点观察和记载,对其植物学特征、生物学特性、生境及经济性状等作了重点调查,并作了种下分类.本文将新疆野杏分成44个种下类型,以供研究及利用者参考.     

JR90无线数据采集系统

JR90数据采集系统采用星型网络拓扑结构,并用STD模板,组态灵活。通讯采用异频单工无线方式,复盖方圆50公里,采集的物理量可高达800个.系统采用并行传输、语音和警声报警等先进技术,软件丰富,功能齐全.系统的应用使调度手段科学化,数据信息及时、准确。文中还对通信处理机程序作了重点介绍.     

微机在罗兰A定位仪中的应用

本文讨论了针对我国沿海情况如何依据罗兰A测得的时差求出经纬度及海区信息,并对运算过程精度的提高提出了一些见解.最后讨论了全自动罗兰A定位仪的实现及会遇到的困难.     

铅和锌混合液在菲律宾蛤仔体内的积累及其致毒效应

研究了铅,锌对菲律宾蛤仔的急性毒性,以及铅,锌混合液在菲律宾蛤仔体内的积累和对过氧化氢酶酶活性的影响。结果表明：铅的毒性略大于锌的毒性：铅、锌混合液对蛤仔体内的重金属吸收存在交互作用。     

硫代硫酸盐从金精矿中提金新工艺的研究

采用硫代硫酸盐从朝阳地区金精矿中提出金银，金银浸出率可达９７％和４５％，浸出周期仅为常规氰化法的１／３，并研究了硫代硫铵浓度，添加剂。浸出温度，浸出时间，液固比，粒度等因素对浸出率的影响。     

（P,P）图的可嵌性定理

设G是一个简单无向图,称G是(P,P)图,如果|E(G)|=|v(G)|.若G同构于6某个子图,则称G可嵌入6,本文用极其简捷的方法证明了:阶数大于9的(P,P)图可嵌入其补图内的充要条件是G不和图(1)中的任一个图同构。     

二茂铁及其衍生物在分析中的应用Ⅲ——二茂铁阳离子紫外分光光度法测定食品中微量铁

本文研究了二茂铁阳离子的紫外吸收光谱并用于食品样品中微量铁的测定.选氯仿做溶剂兼萃取剂,lN盐酸做介质.在选定的操作条件下,试剂二茂铁与Fe~(3-)发生氧化还原反应,产生的二茂铁阳离子转入水相.测其紫外吸收光谱,λ_(?)=250nm. ε=4.8×10~3.Fe~(3-)含量在0～6ppm范围内符合比尔定律. 本法用于食品样品中铁的测定,与邻菲罗啉法对照,结果是满意的.对于铁含量在1～15mg/100g的试样,误差不大于3％,相对标准偏差在5％以内.     

M-回路网络的中心选址

研究含边不交回路网络的中心选址问题,给出了一个求其最小直径支撑树的破圈算法,由此得到求其中心的O(mn)阶算法,这里m是网络中含回路的个数。     

五阶段加工硬化理论

分析了金属塑性变形过程中,位错增殖、螺型位错交滑移和刃型位错攀移过程,建立了包括五个加工硬化阶段的位错理论模型。利用计算机,在不同的变形条件下,对理论模型进行了计算,计算结果和实验结果相当吻合。