SiO_2短纤维陶瓷膜制备与气体过滤性能

采用浸浆成型法制备气固分离用SiO_2短纤维陶瓷膜,研究涂膜前后样品的过滤阻力、滤后气体含尘量(VFPM_(2.5))和循环再生性能。对涂膜液的固含量和纤维添加量进行考察,确定适宜的涂膜液制备参数,进而研究浸浆时间和烧成温度对膜过滤性能的影响,通过扫描电子显微镜(SEM)观察样品表面形貌。结果表明:适宜的涂膜液固含量为10%～12.5%,纤维添加量为30%;涂膜过程中,适宜的浸浆时间为60 s,样品的最佳烧成温度为950℃,保温时间为2.5 h;由以上实验条件制备的纤维陶瓷膜过滤效率高且循环再生性能良好。涂膜后样品的孔径明显减小,短纤维完全地覆盖在支撑体表面形成具有3D纤维网络状结构的膜层,膜层厚度为25～30μm。     

聚四氟乙烯微孔膜/双组分熔喷材料复合空气滤材的制备与过滤性能

以聚四氟乙烯(PTFE)微孔膜作为过滤层,聚酯/聚丙烯(PET/PP)双组分熔喷材料作为支撑层,通过非织造热轧技术制备一种空气过滤器用PTFE微孔膜/(PET/PP)双组分熔喷材料复合滤材。讨论了复合滤材的制备工艺,并研究了过滤层(PTFE微孔膜)、支撑层(熔喷材料)和热轧工艺对复合滤材过滤性能的影响。结果表明:制备的复合滤材具有优良的过滤性能,随着双组分熔喷材料中聚丙烯(PP)纤维体积分数的增加,复合滤材的过滤阻力上升;复合滤材的过滤性能主要由PTFE微孔膜提供;热轧工艺对复合滤材的结构和过滤性能都有影响;当PET/PP双组分熔喷材料中PET纤维与PP纤维体积比为30/70、热辊温度为150℃、线速度为8 m/min、辊间压力为180N/cm2时,复合滤材的滤效达到99.95%,滤阻为350Pa。     

二氧化硅气凝胶改性方法及研究进展

为了提高采用溶胶-凝胶法制备的二氧化硅气凝胶的网络强度,介绍了对二氧化硅气凝胶进行改性的3种方法. 以正硅酸乙酯为硅源,采用溶胶-凝胶法和表面修饰工艺,在常压条件下制备了SiO2气凝胶. 傅里叶变换红外光谱仪(FT-IR)测试结果表明,SiO2气凝胶具有较好的疏水特性. 表面修饰剂三甲基氯硅烷在正己烷中的体积分数为6%,表面修饰时间为24h时,气凝胶具有优化的性能.     

天然气用纤维过滤器非稳态性能实验研究

针对天然气工业特点,设计了一套滤芯性能在线检测装置,采用光学粒子计数器OPC对过滤器上、下游粉尘的浓度和粒径分布进行适时测量.使用多分散性粉尘,在实验室内测试了天然气用纤维过滤器的非稳态性能,以及各种操作参数对其性能的影响规律.实验结果表明,纤维过滤器的过滤效率和阻力均随粉尘负荷的增加而增加,根据其变化趋势可分为深层过滤和滤饼过滤两个阶段.过滤速度过高容易导致大粒子穿透,从而使效率下降,纤维过滤器的表观过滤速度应低于0.06 m/s;相对湿度和滤材厚度的增加有利于增大过滤效率,但也会导致阻力的迅速增加.     

天然气用纤维过滤器非稳态性能实验研究

针对天然气工业特点，设计了一套滤芯性能在线检测装置，采用光学粒子计数器OPC对过滤器上、下游粉尘的浓度和粒径分布进行适时测量。使用多分散性粉尘，在实验室内测试了天然气用纤维过滤器的非稳态性能，以及各种操作参数对其性能的影响规律。实验结果表明，纤维过滤器的过滤效率和阻力均随粉尘负荷的增加而增加，根据其变化趋势可分为深层过滤和滤饼过滤两个阶段。过滤速度过高容易导致大粒子穿透，从而使效率下降，纤维过滤器的表观过滤速度应低于0．06m／s；相对湿度和滤材厚度的增加有利于增大过滤效率，但也会导致阻力的迅速增加。     

基于纳米纤维覆层的除尘滤料制备

采用静电纺丝技术制备了用于除尘领域的涤纶纳米纤维膜,利用扫描电子显微镜对纤维膜微观形貌进行表征,确定了最佳纺丝条件,并将该条件下制得的纳米纤维膜附着在除尘滤料表面,对其进行阻力特性、分级计数效率及动态过滤性能测试.结果表明,15kV纺丝电压、21cm接收距离、18%纺丝液质量分数为最佳纺丝条件,在该条件下制备的纳米纤维过滤材料阻力较低,清灰性能良好,对3μm以下的微细粒子过滤效率达到99.99%以上,效率提升明显,能有效控制微细颗粒物.     

溶胶-凝胶法氧化铈-氧化钛涂层的成膜行为研究

采用溶胶-凝胶法,以Ce(NO3)3·6H2O和Ti(OC3H7)4为前驱体制备了不同铈钛比的CeO2-TiO2复合薄膜.对溶胶的黏度和粒度等物理性质进行了测试,运用循环伏安和双电位阶跃等方法分析了CeO2-TiO2复合薄膜的电化学性能.结果表明:溶胶的黏度和粒度对镀膜效果和薄膜的电化学性能有着直接的影响;n(Ce):n(Ti)-3:4,溶胶老化时间为62 h时,其黏度为4.5×10-3 Pa·s,粒度为250 nm时,在Li+离子注入/脱出过程中,薄膜有较快的电化学响应和较高的电荷容量(4.5mC/cm2),薄膜具有良好的循环可逆性,可在智能窗、锂离子电池等器件中作为离子储存电极.     

La2O3对LiFePO4正极材料的修饰改性研究

采用碳热还原法合成橄榄石型LiFePO4正极材料,并用溶胶-凝胶法在其表面修饰La2O3颗粒。通过X射线衍射(XRD)、场发射扫描电镜(FE-SEM)等方法对表面修饰前后的LiFePO4进行表征,分析了表面修饰前后LiFePO4物理性质的变化,并进行了恒流充放电测试和循环伏安测试,研究了表面修饰对LiFePO4电化学性能的影响。结果表明,La2O3表面修饰没有改变LiFePO4材料的晶体结构,LiFePO4材料经La2O3修饰后,其电化学性能显著改善。     

高温除尘用纤维多孔陶瓷材料的制备及性能

利用陶瓷纤维直径不同的特点,采用一步成形的方法制备具有梯度结构的纤维多孔陶瓷。采用扫描电镜(SEM)和金相显微镜对纤维多孔陶瓷的显微结构进行表征,并对影响材料性能的各种因素进行分析。结果表明:800℃烧成样品的抗折强度为6.7 MPa,气孔率最大达到76%,室温下空气流速为1 m/min时的过滤阻力为98 Pa,过滤阻力随着烧成温度的上升而逐渐下降。     

掺镍钛酸钡纳米粉体及其陶瓷的溶胶-凝胶制备

目的研究焙烧温度和烧结温度对由溶胶-凝胶法制备的掺镍钛酸钡样品微结构及介电性能的影响。方法采用溶胶-凝胶法制备了掺镍钛酸钡粉体及其陶瓷,通过FT-IR,XRD,SEM和TEM对干凝胶粉体、预烧粉体以及陶瓷进行了表征,并测定陶瓷的介电性能。结果采用溶胶-凝胶法可制备纳米级(30~80 nm)掺镍钛酸钡粉体及其细晶陶瓷(1~3μm);较高的焙烧温度有利于四方相钛酸钡的形成和晶粒的长大,但降低了陶瓷的介电常数;较高的烧结温度有利于陶瓷居里点介电常数的提高,合适的焙烧温度及烧结温度分别为800℃和1 300℃。结论溶胶-凝胶法可制得组成均匀、性能优异的介电材料,是制备多组分掺杂钛酸钡陶瓷的理想方法。     

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     

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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