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.     

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.     

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.     

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.     

科学理性的价值考量

理性是科学的内核，科学是理性的外现。通过回顾科学理性的历史演变以及对其进行概念的厘定，进一步展现了科学理性自身的合理性和非自足性缺陷，并以此为突破口，引入价值判定的标准。科学技术和主体性的异化，植根于理性的独断化，它主要表现为科学主义的误区和科学万能论的乌托邦悲剧。对科学理性的价值考量、追问科学理性的德性归宿已经提上历史日程，并昭示着21世纪人类努力的方向。     

重大事件对城市发展影响研究综述

重大事件对城市在促进当地社会经济发展,提高举办城市的知名度方面具有重要影响。具体地体现在以下八个层面：城市整体发展、城市空间、城市规划和建筑设计、城市经济社会发展、城市生活、城市公共管理、提升城市形象与城市国际化。     

论中国共产党进入社会主义后的基本执政规律

社会主义是中国人民走向共同富裕的必由之路，中国共产党是中国社会主义事业的核心领导力量。党必须始终做到权为民所用、情为民所系、利为民所谋．不断密切与群众的血肉联系，使党成为立党为公、执政为民、以人为本的执政党；党必须不断改进执政方式、完善执政方略，使党成为科学执政、民主执政、依法执政的执政党；党必须珍惜和培育执政的合法性资源，在执政实践中，对指导我们思想的理论基础既要坚持又要发展，对我国社会主义基本制度既要坚持又要完善，在推进发展这个党执政兴国的第一要务时既要加快又要全面，使党成为与时俱进、求真务实、为民造福的执政党；党必须坚持以改革的精神加强党的建设，在党的自身建设上既要全面推进又要重点提高执政能力，使党成为政治坚定、勤政高效、清正廉洁的执政党。     

提高现代收信机选择性的途径

选择性是收信机的重要质量指标.提高选择性对增强收信机的抗干扰能力具有重要作用.本文在阐明它的物理意义的基础上,提出了各相关量的指标,并分析归纳改善它的技术途径.     

西安古都文化产业化的理性思考

随着知识经济的不断发展,以文化为载体的区域经济竞争在我国逐渐展开。西安作为13朝古都建地,拥有大量的皇宫遗迹、宗教遗存和其他古建筑群等显型文化,同时还拥有反映帝王政治、民风民俗和盛世商贸等隐型文化。西安应充分利用自身独特的古都文化资源优势,将城市发展定位于打造“东方古都,世界神韵———五千年东方文化的辉煌与传承”的品牌上,正确处理好产业选择中的底牌与王牌关系、资源开发中的隐文化与显文化的关系、开发模式中的文化开发与文化保护的关系,全方位发掘古都文化资源并实现产业化,从而增强西安经济竞争力,推动西安经济的快速发展,提升西安城市品牌的知名度和美誉度。     

对北京学基本理论的初探

从北京学产生的时代背景,北京学的学科体系位置,北京学的科学概念,研究对象,研究任务,研究范围以及研究方法等方面,对北京学的基本理论进行了初步的探讨,提出了由自然环境与人类聚落所构成的地方综合体的概念。     

ZigBee协议栈的安全体系综述

ZigBee技术作为无线传感网络领域的新兴技术获得广泛应用,其安全性日益重要。本文从现存的ZigBee安全体系入手,针对ZigBee的安全结构、安全服务、安全模式、安全组件、安全密钥和信任中心以及各层的安全措施展开论述,并具体介绍了ZigBee实现安全的步骤,最后提出一种可以提高ZigBee安全性的密钥管理方案的新思路。     

高校校园体育文化建设新析

从校园体育文化的内涵入手，对高校校园体育文化的特点和建设进行了分析，提出了高校校园体育文化建设的途径和方法．     

劳伦斯“血性意识”之反宗教话语内涵解读

研究劳伦斯在其作品中展示出来的"血性意识"之反宗教性话语,有助于我们探索在他的作品里始终如一体现出的"血性意识"哲学理念所蕴藏的极为丰富的文学内涵:在历史上,这一理论不仅起到反抗传统道德伦理对人性束缚从而解放人们身体的作用,而且在对抗宗教给人的肉体和思想套上枷锁的教义方面,也起着其他文学作品所不可替代的效果。     

语气副词"明明"的多角度分析

常规的词典对语气副词“明明“的解释都是通过近义词和它出现的句法环境来说明,这样的解释过于简略,特别是在对外汉语教学中很难让留学生真正掌握其意义和用法.通过对“明明“出现的语义环境、句法环境以及它所传达的语气等方面来对它进行多角度的分析,从而使该词有更细致理性的使用规则.