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1.
《矿物冶金与材料学报》2021,28(12):2001-2007
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.  相似文献   

2.
《矿物冶金与材料学报》2021,28(12):1908-1916
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.  相似文献   

3.
4.
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.  相似文献   

5.
《矿物冶金与材料学报》2020,27(10):1347-1352
A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr0.9FeNi2.5V0.2Al0.5 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.  相似文献   

6.
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.  相似文献   

7.
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.  相似文献   

8.
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.  相似文献   

9.
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.  相似文献   

10.
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.  相似文献   

11.
传承民歌、弘扬民歌、发展民歌是振兴中国民族音乐的重要内容,在高师声乐小组课中通过感受民歌、探究民歌,表现民歌三方面教学,提出以民歌教学为主要内容的高师声乐小组课模式的可行性及现实意义。  相似文献   

12.
The role of sex steroids in the acquisition and production of birdsong   总被引:2,自引:0,他引:2  
P Marler  S Peters  G F Ball  A M Dufty  J C Wingfield 《Nature》1988,336(6201):770-772
Male birdsong is generally regarded as a secondary sexual characteristic under the control of gonadal steroids. Song typically waxes and wanes with the seasonal cycle of testicular growth and regression and decreases after adult castration. Testosterone therapy reinstates song, induces it in females, augments it in intact males, and spring testosterone profiles correlate with seasonal song production. Thus, testosterone has been viewed as a major factor in song acquisition and production acting either directly, or after aromatization within the brain. We show here, however, that song learning and early phases of the development of singing both take place in castrated male birds with no significant levels of testosterone in their blood plasma. Testosterone seems to be required for song crystallization, however. Oestradiol was unexpectedly still present after castration, evidently from a non-testicular source, throughout the period of male song acquisition.  相似文献   

13.
姜夔的琴歌《古怨》是姜夔作品中唯一一首琴歌作品,形式和内容有别于其他形式的曲辞,有着独特的审美特点。此琴歌用的是侧商调,调式古老流美,旋律古雅悠长。琴歌曲词分为三个部分,分别有着烟雾迷津中的苍茫缥缈,黍离之悲哀婉凄凉,野云孤雁的清空洒脱等审美特点。这些特点与作者的身世和所处环境相关。此外,作品中双关,隐喻,用典等艺术手法的运用恰到好处。此琴歌抒发了作者对身世凄凉,世道变迁,家国破碎的感叹。  相似文献   

14.
夔州竹枝歌舞与三峡地区诸歌舞形式的关系   总被引:1,自引:0,他引:1  
三峡地区人民自古能歌善舞,创造出了绚丽多彩的艺术文化,包括夔州竹枝歌舞、土家族摆手舞、开县巫舞、打连宵等等,其中夔州竹枝歌舞是众多舞蹈形式中的一枝奇葩,对其他歌舞形式产生了重要影响。文章重点探讨了夔州竹枝歌舞与摆手舞、打连宵及巫舞之间的关系,以便我们能够对夔州竹枝歌舞以及三峡地区其他歌舞形式有更深入的理解。  相似文献   

15.
朝鲜半岛新罗时期的国语诗歌一般称之为新罗乡歌。《处容歌》创作于新罗宪康王五年(公元879年),是25首新罗乡歌作品中的一首,收录在朝鲜半岛古代文献资料《三国遗事》中。《处容歌》所具有的传统价值观念、民俗信仰、生活理念等内容对朝鲜半岛的人们产生了深远的影响。  相似文献   

16.
花灯是我国重要民间剧种之一,少数民族众多的云南又是花灯的繁衍地,玉溪花灯是云南花灯的一个重要支派,在云南花灯中扮演着举足轻重的地位。对玉溪花灯的发展现状及其改革路径的分析与探索,可以为以玉溪花灯为代表的地方戏曲艺术的发展之路提供借鉴。当前玉溪花灯的现状主要表现为舞台花灯艺术与民俗花灯的分离,实现两者的结合是促进玉溪花灯发展的关键。  相似文献   

17.
新编民歌《兰花花》属于叙事性独唱歌曲,它既保留了原来的风格,又被赋予了新的音乐内容,既具有浓郁的民族地域特色,又有西洋交响乐气势磅礴的魅力,为演唱者提供了一个更大的艺术创新和发挥的空间。演唱者应对作品内容、语言、主题、时代背景、地域风格、乐句划分、伴奏织体、速度、力度、表情述语的变化进行推敲表琢磨,加强综合艺术表现力,以获得较完美的演唱效果。  相似文献   

18.
巴蜀民歌在历史的发展过程中沉淀了众多的生活内涵、情感内涵、语言内涵、历史内涵以及审美内涵等深层文化、历史信息。解读这些民歌中的历史遗存有助于提高对巴蜀民歌进行深入研究的重要性的认识,对于深化民歌的艺术审美、认识其实用性功能具有不同寻常的意义。同时,它也是发展与完善巴蜀民歌传统和精髓的有效路径之一。  相似文献   

19.
Sleep affects learning and development in humans and other animals, but the role of sleep in developmental learning has never been examined. Here we show the effects of night-sleep on song development in the zebra finch by recording and analysing the entire song ontogeny. During periods of rapid learning we observed a pronounced deterioration in song structure after night-sleep. The song regained structure after intense morning singing. Daily improvement in similarity to the tutored song occurred during the late phase of this morning recovery; little further improvement occurred thereafter. Furthermore, birds that showed stronger post-sleep deterioration during development achieved a better final imitation. The effect diminished with age. Our experiments showed that these oscillations were not a result of sleep inertia or lack of practice, indicating the possible involvement of an active process, perhaps neural song-replay during sleep. We suggest that these oscillations correspond to competing demands of plasticity and consolidation during learning, creating repeated opportunities to reshape previously learned motor skills.  相似文献   

20.
电视剧《闯关东》主题曲《家园》是深受人们喜爱的一首歌曲。主题曲的歌词精彩,寓意深刻;它发展手法自然合理;整体布局错落有致,富有创意;段落对比鲜明;调性变换虽然频繁,但自然有效果;它的Rap节奏与《摇篮曲》的交织结合新颖;很好地表达了顽强坚韧、勇于抗争、重义轻利以及与人为善的“闯关东精神”,具有很强的艺术魅力。  相似文献   

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