蛇纹石尾矿制备高纯氧化镁工艺条件的研究

文章研究了以蛇纹石尾矿为原料制备高纯氧化镁的新工艺,并考察了粗硫酸镁溶液净化终点pH值的变化对样品纯度的影响;同时,在精制硫酸镁溶液浓度、煅烧温度和煅烧时间确定的前提下,通过正交实验确定沉淀反应的最佳工艺条件为:反应温度40℃,硫酸镁与碳酸钠摩尔计量比为1:1.4,反应时间30 min,陈化时间30 min;在此条件下,所得样品中wMgO≥99.16%,wCaO≤0.08%.     

硫酸镁还原热解制备高纯氧化镁

用菱镁矿和工业纯硫酸来制备七水硫酸镁,进一步脱水得到无水硫酸镁。以无水硫酸镁和木炭粉为原料,经高温煅烧制备高纯氧化镁。研究反应物的配比、煅烧温度、煅烧时间以及粒径对产品纯度的影响。采用X线衍射和扫描电镜对样品进行表征。通过单因素实验确定的最佳工艺条件为:硫酸镁和炭粉的最佳配比8:1,煅烧时间2 h,煅烧温度800℃,粒径109μm。研究结果表明:在最佳工艺下,样品纯度达到99%,粒径分布介于109～700μm之间,单分子表面为多孔蓬松高比表面。     

天然气还原热解硫酸镁制备高纯氧化镁

利用盐湖氯化镁和硫酸制备七水硫酸镁,将七水硫酸镁脱水得到无水硫酸镁.采用天然气还原热解无水硫酸镁得到高纯氧化镁.通过单因素实验考察了还原热解温度、热解时间、硫酸镁的粒径和天然气气体流量对硫酸镁转化率的影响,通过正交试验优化了还原热解的条件.采用X射线衍射和扫描电镜对还原热解产物进行分析和表征.氧化镁的最佳制备条件:热解温度为1000℃,热解时间为30 min,硫酸镁粒径为75μm,天然气气体流量为25 mL·min-1.温度是影响硫酸镁转化率的主要因素.在最佳制备条件下,硫酸镁的转化率达到99.27％,氧化镁的纯度达到99.5％,制取的氧化镁单分子均匀,表面为多孔蓬松,具有高比表面积.     

麻疯树油制备生物柴油中SO42-/TiO2固体酸研究

利用高酸值麻疯树油中游离脂肪酸与甲醇酯化反应作为目标反应,通过直接煅烧工业原料偏钛酸,制得高酯化活性的ST固体酸.系统地研究了制备条件、反应条件对其酯化活性的影响.ST固体酸制备过程中,煅烧温度是一个敏感的因素,而煅烧时间影响较小.最佳的制备条件为:500℃,2 h.最佳的反应条件为:反应温度为90℃,醇酸摩尔比为20∶1,催化剂用量为油重的4%,反应时间为2 h.在此条件下,游离脂肪酸的转化率可达97%以上.FTIR研究、S质量分数测定表明:活性组分溶剂化流失、表面积炭为其失活的主要原因.再硫化或在氧气中煅烧是较为有效的再生方法.     

麻疯树油制备生物柴油中SO42-/TiO2固体酸研究

 利用高酸值麻疯树油中游离脂肪酸与甲醇酯化反应作为目标反应,通过直接煅烧工业原料偏钛酸,制得高酯化活性的ST固体酸.系统地研究了制备条件、反应条件对其酯化活性的影响.ST固体酸制备过程中,煅烧温度是一个敏感的因素,而煅烧时间影响较小.最佳的制备条件为:500℃,2h.最佳的反应条件为:反应温度为90℃,醇酸摩尔比为20:1,催化剂用量为油重的4%,反应时间为2h.在此条件下,游离脂肪酸的转化率可达97%以上.FTIR研究、S质量分数测定表明:活性组分溶剂化流失、表面积炭为其失活的主要原因.再硫化或在氧气中煅烧是较为有效的再生方法.     

低品位菱镁矿制备纳米氧化镁的工艺优化研究

研究了低品位菱镁矿煅烧工艺优化及其对纳米氧化镁产品性能的影响问题.为了保证轻烧镁粉的活性和低品位菱镁矿的充分利用,通过调节煅烧温度和时间,发现低品位菱镁矿煅烧的适宜工艺条件为750℃煅烧1.5 h.以此法得到的轻烧镁粉为原料,配合工业级硫酸铵和碳酸氢铵以及自制的复配型表面活性剂,采用液相均匀沉淀法,制得平均粒径为60 nm的纳米氧化镁粉体,优选的沉淀反应条件为85℃下反应85 min,优选的前驱体煅烧工艺条件为550℃下煅烧1.5 h.利用激光粒度分析仪、XRD衍射仪及扫描电镜表征了产品性能,结果表明,本实验方法制得的纳米氧化镁粉体颗粒形状均匀,粒径分布窄,分散性良好.     

负载型固体碱 NaF／NaX 的制取及其在 DHA 制备中的应用

运用浸渍法制取了固体碱NaF/NaX,并以NaF/NaX为催化剂、以乙酰乙酸乙酯为原料制备了脱氢乙酸.分析讨论了负载量、煅烧温度、煅烧时间、催化剂用量、反应温度和反应时间对脱氢乙酸产率的影响.结果表明,制取NaF/NaX的最佳条件是:NaF负载量20%、煅烧温度600℃、煅烧时间7 h;制备脱氢乙酸的最佳条件是:催化剂用量0.02 g、温度210℃、反应时间7 h,在此条件下制备脱氢乙酸,产率可达82.5%.     

氧化镁晶须制备及影响因素考查

为了促进氧化镁晶须的规模化生产与工业应用,采用前驱物煅烧法制备了氧化镁晶须.以氯化镁为原料、碳酸钠为沉淀剂制备了结晶良好的水合碳酸镁晶须;控制碳酸镁的热分解条件保持晶须形状不被破坏,在煅烧情况下将其转变为氧化镁晶须.采用X射线衍射仪和扫描电子显微镜对产物的组成、形态和结构进行了表征.结果表明,所得氧化镁晶须直径2～5 μm,长度约为60 μm.另外,对影响晶须形成的一些主要因素进行了初步探讨,同时简要介绍了利用碱式氯化镁、碱式硫酸镁获得氧化镁晶须的方法,探索性地拓展了氧化镁晶须的工业生产.     

耐水合氧化镁的研制

高纯氧化镁具有热传导率高,电绝缘性优良的特性,是制备高集成化电子元件的重要原料之一。但普通方法生产出来的氧化镁极易水化,严重限制了该化合物在电子元器件生产中的应用。作者由氢氧化镁途径制备出了具有一定耐水合性能的高纯氧化镁,并对合成条件对产品性能的影响进行了探索,为耐水合氧化镁的进一步研究奠定了基础。     

CaO/MgO和CaO/Ca9Al6O18吸收CO2的循环反应特性研究

钙基吸收剂是CO2捕集技术中常用的吸收剂,但随着循环次数的增加,天然钙基吸收剂循环反应特性下降明显.采用葡萄糖酸钙(Ca(C6H11O7)2)与葡萄糖酸镁(C12H22MgO14)及L-乳酸铝([CH3CH(OH)COO]3Al)作为前驱物,通过湿法混合的方法处理,制得了5种新型钙基吸收剂,试验研究了其吸收CO2的循环吸收能力及循环稳定性,分析了吸收剂组分、煅烧温度、煅烧气氛等条件对新型吸收剂循环反应特性的影响规律.研究结果表明,选用此前驱物制备的吸收剂,其循环反应特性明显高于传统的钙基吸收剂;其中,CaO/MgO(75wt%/25wt%)吸收剂具有最好的循环吸收能力,CaO/Ca9Al6O18(75wt%/wt25%)吸收剂具有最好的循环稳定性.通过研究煅烧条件对这两种吸收剂循环反应特性的影响,得到:850℃时,吸收剂表现出最佳的反应特性,而随着温度的升高,吸收剂的循环吸收能力有所下降;煅烧气氛对吸收剂循环吸收特性的影响与煅烧温度有显著的关系.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with