硅单质法制备纳米SiO2及其分散稳定性研究

以硅单质为主要原料，碱催化剂制备硅溶胶，在“原位生成”纳米SiO2的同时，采用“原位分散”和“原位表面改性”的方法，制备了粒度为8－15nm的SiO2水解散液，研究了反应时间，温度，介质PH值，分散剂和表面改性剂等因素对纳米粒子粒径，粒径分布分散稳定性的影响；该制备方法简便易行，价格便宜，并有效解决了纳米SiO2在水相中的稳定分散问题，具有广阔的应用前景。     

亲油型纳米SiO2的制备及其分散稳定性研究

以硅酸盐为主要原料，通过离子交换制备了纳米SiO2水分散液，研究了原料浓度、表面改性时间、温度、加料方式、改性剂用量等因素对纳米粒子粒径、粒径分布及分散稳定性的影响；该制备方法简便易行，价格便宜，经表面改性后的纳米SiO2粒径小，粒径小，粒径分布窄（φ为8-15nm)，耐酸及耐温性能好，有效解决了纳米SiO2在水相中的稳定分散问题，具有广阔的应用前景。     

不同表面改性的纳米SiO_2/MC尼龙6复合材料

采用两种原位表面修饰的纳米SiO2(RNS和DNS)通过原位聚合的方法制备了纳米SiO2/MC尼龙6复合材料,测试了材料的力学性能,RNS和DNS的加入均能使MC尼龙6的力学性能有较大提高,在一定的范围内对复合材料同时具有增强和增韧的作用,RNS的影响要大于DNS;同时通过SEM、TGA等分析手段,考查了纳米SiO2在聚合物基体中的分散情况、热稳定性.结果表明,纳米SiO2粒子在基体中分布均匀,两种纳米SiO2的加入均大大提高了复合材料热稳定性,使MC尼龙6的起始降解温度分别提高10℃和21℃.     

纳米SiO2表面接枝及其在原位乳液聚合体系中的分散稳定性

用湿法改性方法将硅烷偶联剂接枝在纳米SiO2表面上,并分析了pH值、反应时间、反应温度及硅烷偶联剂的加入量对接枝效果的影响,继而讨论了接枝后的纳米SiO2在原位乳液聚合过程中的分散稳定性.结果表明,较佳的改性工艺条件为:pH值为3~4,反应温度为80℃,反应时间为120 min,硅烷偶联剂的加入量为纳米SiO2重量的10%左右.接枝了硅烷偶联剂的纳米SiO2,能够使乳化剂聚集在其表面上,形成“胶束”区域,从而提高了在乳液聚合体系中的分散性和稳定性.     

单分散纳米二氧化硅的制备及影响因素分析

以正硅酸四乙酯(TEOS)为原料采用Stober法制备了单分散、粒径分布均匀、平均直径范围在250～800nm的纳米二氧化硅微球.通过SEM和XRD表征手段,探讨了水、TEOS和氨水用量对SiO2形貌和粒径的影响.结果表明,添加适量的水会得到粒径较大、均匀且分散性好的SiO2微球;随氨水和TEOS用量增多,SiO2粒径增加;若氨水用量太少,则得到粒径虽小但圆度差、表面不光滑的SiO2.     

Pickering乳液法原位制备载药磁性SiO_2空心球及缓释性能

采用共沉淀法制备纳米Fe3O4颗粒,然后通过Pickering乳液模板法原位将布洛芬和纳米Fe3O4颗粒包覆在SiO2空心球中,制备出载药磁性SiO2空心球,对其组成、结构及药物释放性能进行了表征。研究结果表明:载药磁性SiO2空心球粒径大小平均为2μm,壁厚约为240 nm,内含布洛芬;原位载药可使空心球的壁厚增加;该材料适合用作药物的载体,具有缓释效果。     

纳米SiO2/聚丙烯酸酯复合乳液涂料的研制

采用“原位复合”方法合成了纳米SiO2／聚丙烯酸酯复合乳液,以此乳液为基料配制的乳胶涂料具有性能好、无污染、价格低等优点。介绍了纳米SiO2/聚丙烯酸酯复合乳液及其乳胶漆的配方和制备工艺,研究了纳米SiO2用量对涂料性能的影响。     

纳米SiO2粉体的制备及其性质研究

采用溶胶—凝胶法制备了纳米SiO2,研究了3种干燥条件对制备纳米SiO2粉体的影响,对制备的纳米SiO2粉体的表面结构做了分析。结果表明:通过CO2超临界流体技术制备的SiO2超细粉体分散性好,比表面积高,粒径为30nm左右。     

微乳液法制备纳米二氧化硅

制备 OP-10/正辛醇/环己烷/氨水微乳液.在该微乳液中,由正硅酸乙酯在碱性条件下受控水解反应制备了 SiO2纳米粒子.通过红外光谱(FT-IR)、X射线衍射(XRD)、透射电镜(TEM)分别对样品结构及形貌尺寸进行了表征.探讨了水与表面活性剂摩尔比(R)、水与正硅酸乙酯摩尔比(H)对SiO2纳米粒子粒径的影响.结果表明制备的SiO2粒子为无定型球形颗粒,粒径为 80～105nm,SiO2纳米粒子粒径随着R和H的增大而增大.     

Ag-SiO_2纳米复合颗粒的脉冲激光控制合成

分别以质量分数为0%,3%,20%微米尺寸的SiO2粉末与微米尺寸的Ag粉末形成混合靶材,利用脉冲激光气相蒸发-液相收集控制合成Ag及Ag-SiO2纳米复合颗粒.采用透射电镜、X光衍射、红外光谱等分析技术,对制备样品的形貌、组织结构及其合成机理等进行了研究.结果表明,制备的Ag-SiO2纳米复合颗粒外观呈球形,主要粒径在15~25 nm范围,Ag-SiO2纳米复合颗粒具有比单相Ag颗粒更好的分散性;Ag-SiO2纳米复合颗粒呈混合复合结构,随着SiO2含量的增加纳米复合颗粒的光谱吸收峰出现了蓝移现象,SiO2复合具有调节纳米Ag颗粒光学性能的功能;液相中的乙二醇起到了原位分散纳米复合颗粒的作用.     

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     

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     

Journal of Donghua University ( English Edition) Contents of Volume 31

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Brief Introduction to “Journal of Jilin University( Science Edition) ”

<正>"Journal of Jilin University(Science Edition)"is a comprehensive academic journal in the fields of science sponsored by Jilin University and administrated by the Ministry of Education of the Peoples Republic of China.The journal started publication in 1955.The original name at starting publication was"Journal of Natural Science of Northeast People University",which was changed into"Acta Scientiarum Naturalium Universitatis Jilinensis"in 1958 owing to the name change of the university.The present journal name has