溶胶凝胶和超临界干燥法制备纳米TiO_2粉体

以钛酸丁酯 (Ti(OR) 4 )为原料 ,采用溶胶凝胶法及超临界流体干燥技术制备了纳米TiO2 粉体。采用正交设计法研究了操作条件对反应的影响 ,筛选出了最佳工艺条件。TEM检测表明 ,优化条件下制得的二氧化钛粉体粒径为 11～ 12 .3nm ,且随热处理温度的升高粒径变化不大 ,但团聚加重。XRD结果表明 ,当热处理温度为 5 0 0℃时晶粒为锐钛型 ;当煅烧温度为 80 0℃时晶粒转化为金红石型。BET结果表明 ,二氧化钛气凝胶颗粒的比表面积可高达5 5 6m2 /g ;但随煅烧温度的升高 ,比表面积下降迅速 ;在 5 0 0℃时 ,比表面积只有 94 .6m2 /g。     

以金属铝水解制氢副产品为原料制备α-Al2O3粉体的研究

以金属铝-水反应法制氢的副产品为主要原料,添加表面活性剂十二烷基苯磺酸钠、晶种α-Al2O3和相变促进剂ZnF2,在实验室制得α-Al2O3粉体,并利用ICP、XRD、TG-DSC、SEM、物理吸附仪等对试样进行表征。结果表明,该金属铝-水反应法制氢的副产品干燥后为单斜型三羟铝石(Al(OH)3),纯度高达99.58%,经过1 300℃×3h高温处理后完全转化为α-Al2O3;以十二烷基苯磺酸钠作为表面活性剂,添加1%的ZnF2作为相变促进剂和1%的纳米α-Al2O3作为晶种,该副产品在1 200℃下即可完全转化为α-Al2O3,粉体的比表面积为6.17m2/g,平均粒径为244nm。     

胶态二氧化锆纳米晶/聚甲基丙烯酸甲酯复合物的制备与表征

以正丁基氧锆为无机氧化锆前体,采用水解溶胶-凝胶法合成了不同掺杂量的聚甲基丙烯酸甲酯(PMMA)/二氧化锆(ZrO2)复合物,并用浸渍/提拉镀膜和浇注法制备了PMMA/ZrO2复合薄膜.借助X-射线衍射、红外光谱、紫外-可见光谱、荧光光谱、热重手段研究了复合薄膜的结构和性能.结果表明,相对温和条件下制备得到PMMA与单斜晶型ZrO2纳米复合物,加入纳米氧化锆后,PMMA的热稳定性和可见光透光性能提高,尤其是发光性能明显增强.     

潜伏酸法纳米二氧化硅的制备和表征及对聚乙烯复合物性能的影响

以硅酸钠为原料、己二酸二甲酯为酸潜伏剂,采用溶胶—凝胶法制得纳米二氧化硅(SiO2)粉体,运用红外光谱(FT-IR)、布鲁纳尔—埃梅特—泰勒(BET)比表面积、孔径分布和透射电镜(TEM)等对二氧化硅粉体进行表征。红外光谱表明二氧化硅表面硅羟基与己二酸二甲酯水解产物己二酸的羧基形成氢键。制得的二氧化硅粉体具有较大的比表面积[388～400(m2.g-1)],根据比表面积计算出一次粒径小于10 nm。透射电镜观察到二氧化硅粒子聚集使得二次颗粒尺寸在(80—100)nm之间。采用熔融共混法制备SiO2/低密度聚乙烯(LDPE)复合材料(SiO2/LDPE),研究纳米二氧化硅对LDPE的力学性能和热稳定性的影响。结果表明纳米二氧化硅的加入提高了LDPE的拉伸强度,含3%二氧化硅的复合物的拉伸强度从6.88 MPa提高到8.32 MPa。并且随着纳米粒子含量的增加其断裂伸长率降低,但高温热稳定性增强。     

溶胶凝胶和超临界干燥法制备纳米TiO2粉体

以钛酸丁酯（Ti(OR)4)为原料,采用溶胶凝胶法及超临界流体干燥技术制备了纳米TiO2粉体。采用正交设计法研究了操作条件反应的影响,筛选出了最佳工艺条件。TEM检测表明,优化条件下制得的二氧化钛粉体粒径为11－12．3nm,且随热处理温度的升高粒径变化不大,但团聚加重。XRD结果表明,当热处理温度为500℃时晶粒为锐钛型;当煅烧温度为800℃时晶粒转化为金红石型。BET结果表明,二氧化钛气凝胶颗粒的比表面积可高达556m^2/g;但随煅烧温度的升高,比表面积下降迅速;在500℃时,比表面积只有94．6m^2/g。     

纳米ZrO2晶型对铜基复合材料界面的影响

采用原位化学工艺制备了ZrO2/Cu纳米复合粉末,用粉末冶金法制备了纳米ZrO2/Cu复合材料. 通过TEM观察发现,氧化锆呈单斜和四方两种晶型,不同晶体形态的氧化锆颗粒与铜基体之间具有不同的界面特征. 通过Ansys分析软件对不同形态即不同晶型氧化锆与铜基体的界面进行应力模拟分析,结果发现单斜晶型氧化锆的尖端部位很容易产生应力集中,且比四方晶型氧化锆界面处更容易产生裂纹.     

高比表面积TiO_2纳米颗粒的制备及光催化性能研究

以钛酸四丁酯为钛源,采用流变相法制备出了具有高比表面积的二氧化钛（TiO2）纳米颗粒.采用X射线衍射仪（XRD）,扫描电子显微镜（SEM）和比表面积及孔径分析仪（BET）对TiO2的晶型、形貌及比表面积进行了表征,结果显示产物为锐钛矿型,平均粒径约为8.4 nm,比表面积为423.7 m2/g.光催化实验表明,样品在可见光（λ〉420 nm）下反应180 min后,能将罗丹明B（RhB）降解95%左右.     

以梳型聚合物为模板制备介孔Ag/AgBr/TiO_2纳米复合材料

以钛酸四丁酯为钛源,梳型聚合物为模板,采用溶胶-凝胶法低温水浴制备具有介孔结构的纳米TiO2,通过沉积-沉淀法将Ag/AgBr负载于介孔TiO2纳米微粒表面,制得高比表面积的Ag/AgBr/TiO2纳米复合材料。采用XRD,TEM,N2吸附-脱附和UV-vis DRS等方法对Ag/AgBr/TiO2纳米复合材料进行了表征。结果表明,所制备的纳米TiO2和Ag/AgBr/TiO2纳米复合材料具有介孔结构;Ag/AgBr的引入,减小了介孔TiO2的比表面积(由346m2/g减小为253m2/g),但大幅度提高了其可见光催化活性。在可见光下,Ag/AgBr/TiO2降解甲基橙的速率分别为商品TiO2P25和介孔TiO2的145倍和60倍。     

AlOOH溶胶的制备及其结构与性能表征

以AlCl3·6H2O和氨水为原料、硝酸为解胶剂,采用非均相沉淀法制备了AlOOH溶胶,并通过喷雾干燥法制备了AlOOH溶胶的凝胶粉体.利用TEM、激光粒度分析和ζ-电位测量等考察表面活性剂对AlOOH溶胶粒径分布以及稳定性的影响,采用SEM、BET、XRD等分析煅烧后AlOOH溶胶干燥物的显微形貌、比表面积、孔径分布以及晶化机理.结果表明,添加PEG400可以控制AlOOH溶胶胶粒的尺寸和粒径分布范围; 溶胶经喷雾干燥处理后得到的凝胶粉体流动性好, 颗粒呈圆环状或圆钵状,具有较高的比表面积,且经过1 200 ℃煅烧后其比表面积仍可达185 m2/g.     

CTAB辅助下WO3/ZrO2复合纳米材料的制备及表征

在十二烷基三甲基溴化铵(CTAB)的辅助下,利用水热法制备了WO3/ZrO2复合氧化物纳米样品,利用XRD、TEM、SAED、N2吸附-脱附等方法对样品的形貌、结构、孔径进行了表征.结果表明:氧化钨被氧化锆包覆煅烧后,团聚成网状结构的纳米粒子,其BET表面积为368m2/g,平均孔径为5.29nm,孔分布不均匀,无序程度极高.     

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