六角晶系钡铁氧体纳米晶的制备和表征

采用柠檬酸sol gel工艺 ,制备了Zn2 Z型 ,Zn2 W型 ,Co2 Z型 ,M型平面六角晶系的钡铁氧体钠米晶 .采用X射线衍射分析 (XRD) ,透射电镜分析 (TEM)和热分析对其物相组成、显微结构、反应过程等进行研究 ,发现采用本工艺 ,在 75 0℃的较低温度下 ,就可形成均匀单一的铁氧体纳米晶 ,并深入分析了其反应机制 ;对Zn2 Z型铁氧体的吸波特性进行了研究 ,结果表明 :在X波段 (8～ 12GHz)和Ku波段 (12～ 18GHz) ,有多个吸收峰 ,最大吸收量达 6 5dB ,10dB的带宽达到 6 .5GHz ,说明这是一种优质的宽频微波吸收材料 ,并探究了纳米吸波材料的吸波机理 .     

Y型六角铁氧体的晶化过程研究及性能表征

采用柠檬酸盐溶胶-凝胶法制备Y型平面六角铁氧体Ba2Co2Fe12O22．X射线衍射分析(XRD)结合透射电镜(TEM)分析，对粉体的成分及晶粒形态进行了表征．并结合热重与差热扫描分析(TG-DSC)和红外光谱(IR)分析对铁氧体的晶化过程进行了研究．表征了高频下Y型铁氧体Ba2CoEe12O22电磁参数随着频率的变化，反映了其高频吸收特性．     

热压铁氧体磁头材料的研究

研究了Mn—Zn和Ni—Zn系热压铁氧体的磁性和其他物理性能;磁导率温度曲线,磁谱,静态磁性(4πMs,B_(10),Hc,B_r)以及磁致伸缩λ_(11)和维氏硬度。观察了显微结构对热压铁氧体精密机械加工性能的响影。观测和讨论了机械加工和热处理对热压铁氧体磁性的影响。在系统研究的基础上,研制成功磁盘存贮器用的Ni—Zn热压铁氧体和录象机及计测磁带机用的Mn—Zn热压铁氧体。     

高频功率NiZn铁氧体的高温功耗

采用传统氧化物法制备了具有成分分子式为Ni0.5-xZn0.5CoxFe2O4(x=0,0.01,0.02,0.03)的高频功率NiZn铁氧体,并主要研究了其磁性能在-40～200℃宽温范围内随温度的变化关系.同时,还研究了Co3+的添加量对样品的高温功耗的影响.结果表明,适量地添加Co3+有助于铁氧体晶粒的均匀细化,高频功率NiZn铁氧体的起始磁导率和功率损耗的温度特性也得到了改善,功耗谷底温度随Co3+含量的增加逐步向低温方向移动.在-40～200℃宽温范围内,成分分子式为Ni0.49Zn0.5Co0.01Fe2O4的样品不但具有极低的高频宽温功耗,而且具有良好的温度稳定性,其磁导率比温度系数为3×10-6℃-1,同时其在高温(100～200℃)下的功耗变化范围仅为130～140kW.m-3,最低仅为130kW.m-3(1MHz,10mT).     

2-氯代苯甲醛丙氨酸席夫碱及其3d-过渡金属配合物的合成与表征

合成了2－氯代苯甲醛丙氨酸席夫碱及其与Cu(Ⅱ）、Ni(Ⅱ)、Co(Ⅱ)、Zn(Ⅱ)离子所形成的配合物;以元素分析、摩尔电导、热重、红外光谱、拉曼光谱、^1HNMR谱等手段研究了化合物的组成和配位环境;对所合成的化物进行了抑制超氧自由基的初步实验,发现虽然2－CAZz、2－CACo对DNA具有明显作用,但该系列化合物对超氧自由基的抑制能力较弱。     

柠檬酸溶胶-凝胶法制备钡铁氧体晶相变化的研究

采用柠檬酸溶胶-凝胶法制得钡铁氧体磁性粉末,借助热质量分析(TGA)、红外光谱(FT-IR)、X线衍射(XRD)及扫描电镜(SEM)测试手段研究了不同柠檬酸添加量对煅烧产物晶型的影响。结果表明:当柠檬酸与金属硝酸盐摩尔配比n(CA)/n(MN)≤1.2时,钡铁氧体晶相为W型,当n(CA)/n(MN)=2时,晶相转变为M型;随着柠檬酸量的增加,燃烧产物的晶化温度升高;过量柠檬酸添加改变了中间产物Fe的存在形式,促使γ-Fe_2O_3转化为热稳定性好的α-Fe_2O_3,进而使得W型钡铁氧体的成型温度升高,出现M晶型钡铁氧体。     

纳米晶Ni_(1-x)Zn_xFe_2O_4铁氧体的水热合成与磁性能

采用水热法在180℃下合成纳米级的尖晶石相NiZn铁氧体,使用Χ射线衍射(XRD)、红外光谱(FTIR)、高分辨透射电镜(HRTEM)和振动样品磁强计(VSM)分别表征NiZn铁氧体纳米粉体的相组成、微结构以及磁性能.XRD衍射谱和红外光谱(FTIR)表明180℃合成的纳米晶NiZn铁氧体为单一尖晶石相;高分辨透射电镜照片分析表明Ni0.6Zn0.4Fe2O4颗粒为立方片状,颗粒均匀,尺寸在20nm左右,晶格结构完整,面间距0.44nm.Ni0.6Zn0.4Fe2O4铁氧体的饱和磁化强度(Ms)和矫顽力(Hc)分别为11.9emu·g-1和93.5Oe,NiZn铁氧体的矫顽力随着Zn2+含量的增加而减小,此为A位和B位磁性离子间超交换作用下降所致.     

球形氢氧化镍同时掺杂Co、Zn的研究

从结构上分析了同时掺杂Co、Zn的作用机理,并改变Zn的加入方式,制备并检测了Ni(OH)2的部分物理性能.结果表明化学共沉淀法掺杂Co、Zn,因Ni2+、Co2+、Zn2+的氢氧化物能形成固溶体,使电极缺陷浓度增加,导电性提高,Zn为定价元素,充放电时能稳定活性物质的晶体结构,对抑制过充时形成γ-NiOOH有利;Zn以ZnO2-2的方式引入反应器,与以Zn2+引入反应器相比,所得氢氧化镍的BET比表面、d001、FWHM001和FWHM101值明显增大,晶粒减小,活性物质利用率提高,为制备高活性球形氢氧化镍探索了一条新途径.图3,表1,参11.     

TiO2微粒的掺杂改性与催化活性

用混合溶胶-凝胶法制备了Fe3+,Zn2+,Pd,Co2+,Ni2+,Cr3+等金属离子掺杂的二氧化钛复合微粒.以四环素降解为目标反应,研究了所制备的复合微粒光催化活性与选择性.并用IR、XPS、Raman光谱等技术,探讨了影响复合微粒光催化活性的原因.结果显示掺杂Fe3+、Zn2+的二氧化钛复合微粒对四环素降解具有很高的催化活性与选择性;掺杂Pd的复合微粒催化活性也有所提高.而Co2+,Ni2+,Cr3+等金属离子掺杂的二氧化钛复合微粒的催化活性呈下降趋势.研究认为Fe3+、Zn2+促进二氧化钛微粒光催化活性的原因是由于这些金属离子高度分散在二氧化钛基质中,使基质晶型发生畸变并形成Ti-O-M桥氧结构;这种结构使复合微粒表面缺陷和活性比表面积增加,有利于光生载流子的转移.同时,Ti/Fe复合微粒中Fe抖有利于活性·OH基团的形成.这些活性·OH基团插入有机物的C-H键中,最终导致有机物的完全降解矿化.另一方面,由于Fe3+,Zn2+,Pd特殊的电子构型,有利于浅度捕获半导体的光生电子,使光生电子-空穴对有效分离.而Co2+,Ni2+,Cr3+金属离子的电子构型易深度捕获光生电子,结果可能形成了电子-空穴复合中心;导致半导体的量子效率和催化活性下降.     

溶胶-凝胶自燃烧法一步合成钇正铁氧体纳米晶及其磁性能

以Fe(NO3)3、Y(NO3)3、柠檬酸、乙二醇以及NH4NO3为原料,通过溶胶-凝胶自燃烧方法一步合成单相钙钛矿结构钇正铁氧体(YFeO3)纳米晶.借助X线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、热质量-差热分析(TG-DTA)、场发射扫描电镜(FESEM)及振动试样磁强计(VSM)等结构与性能测试手段,对凝胶的形成、自燃烧反应过程及其产物纳米晶粉体的微结构特征与磁性能进行分析、测试与表征.在溶液pH对相关金属离子配合程度影响理论计算的基础上,在柠檬酸与金属离子摩尔比值1.5、乙二醇与柠檬酸摩尔比值1.5、pH=6.0以及氧化度Q=80%的实验条件下,采用溶胶-凝胶自燃烧过程一步合成出的单相钇正铁氧体纳米晶颗粒大小均匀、平均尺寸约90nm.经研磨与600℃退火处理后的钇正铁氧体纳米晶的室温磁化曲线表现出弱的反铁磁和明显的顺磁特征,矫顽场为2.17×104A/m,顺磁磁化率为1.54×10-3,在8×105A/m外磁场下磁化强度为3.55×103A/m.     

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.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

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