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.     

Analysis of the Variations of Body Build of Middle-and Old-aged and Research on the Prototype

The characteristics of body build of middle - and old -aged women and its rule of variations as well as the basic sizes of various parts are discussed. All these are based on the body measurements of this age group, and also on the statistical studies of the measurement data. By setting the regression equation, the calculating formulae of various control parts are obtained, thus establishing the prototype of this age group for women.     

3-溴-4-羟基苯甲醛的制备

以工业对羟基苯甲醛和溴素为原料，CHCl3为溶剂高收率地制备了一溴醛。一溴醛收率94，5％，二溴醛收率5．5％，溶剂CHCl3之回收率为98％。     

关键层理论在保水开采中的应用

在绿色开采思想的指导下,对关键层理论在保水开采中的应用进行了分析。通过算例讨论了三者的关系并分析了岩层变形一渗流耦合系统的复杂性特征,提出应用复杂系统动力学理论解释突水机制的初步设想。研究表明,在承载关键层破断前,承载关键层同时也是保水关键层;在承载关键层破断后,不再具有隔水作用,而保水关键层此时由渗流关键层充当;如果承载关键层破断,并且渗流关键层不存在,则会发生突水现象。岩层变形一渗流耦合动力学系统是具有时变边界、非线性、非均匀性和非连续性等特征的复杂系统。将复杂系统动力学引入突水防治理论研究,可以从本质上描述突水的过程。     

新试剂2-(2-氯-4-硝基苯偶氮)-6-异丙基苯酚的合成,结构和性质研究

以２－氯－４－硝基苯胺为原料,经重氮化后与邻异丙基苯酚偶联,得到２－（２－氯－４－硝基苯偶氮）－６－异丙基苯酚（２－Ｃ１－４－ＮＯ２－ＢＡＩＰ）,测定了其离解常数,并研究了它与金属离子的显色反应。     

抗滴虫药1—（2—乙基磺酰基乙基）—2—甲基—5—硝基咪唑的合成

文中报道了一种抗滴虫药物1-(2-乙基磺酰基乙基)-2-甲基-5-硝基咪唑[即替硝唑,(1)]的简便合成方法。该方法以2-甲基-5-硝基味唑(5)为原料,(5)与β-羟基乙基乙硫醚(4)在酸催化下缩合生成1-(2-乙硫基乙基)-2-甲基-5-硝基味唑(6),过量的2-甲基-5-硝基咪唑可回收利用,(6)经过氧化氢氧化生成替硝唑。     

论汉宣帝增立《春秋毂梁传》博士的原因

汉宣帝增立《春秋毅梁传》的博士有一定的感情因素;将《春秋觳梁传》的政治思想作为基本的统治思想,使尖锐的社会矛盾有所缓和;强调血缘正统,其他皇室子孙无权觊觎皇位;在政府组织上,从上至下培植一大批为汉宣帝自己可用之人,却促成了经学知识分子精英阶层的形成。     

3,5—二溴—PADAP分光光度法测定SCN~-离子的研究

本文研究了在酸性介质中,用3,5-二溴—PADAP作显色剂与IO_3~-和SCN~-离子形成深兰色配合物,其表现摩尔吸光系数为2.7×10~4L·mol~(-1)·cm~(-1),提供了测定微量SCN~-离子的新方法,并用于唾液和尿液中SCN~-含量的测定。     

新型3一辛氧基一2一羟丙基一N，N一二乙基苄基氯化铵相转移催化剂的合成

合成了一种新型含２一羟丙基的季铵盐相转移催化剂。     

关于拟半E-凸函数的一个新的判别准则

首先给出了集合A={λ∈[0,1]:f(λE(x) (1-λ)E(y))≤max{f(x),f(y)},(A) E(x),E(y) ∈M}的稠密性证明,然后利用此引理并在E:Rn→Rn为线性映射,f:M(∈)Rn→R为上半连续的条件下,给出了拟半E-凸函数的一个新的充要条件,从而简化了对拟半E-凸函数的判别,为进一步认识和研究E-凸函数、半E-凸函数、拟半E-凸函数及其他广义凸函数提供了新的思路.     

吲哚3—丙酸邻菲啰啉钇三元配合物的合成及性质

本文报道首次合成钇三元配合物,经过元素与化学分析,确定配合物组成为:YP_3(phen)(P为吲哚—3—丙酸根,phen为邻菲啰啉)。通过化学分析、红外光谱。热谱,~1HNMR谱、X-射线粉末衍射等方法对新合成三元配合物的结构及性质进行了研究。