纳米二氧化钛的制备及其光催化性能

分别采用水热法和溶胶-凝胶法制备了TiO2纳米粉体;利用X射线衍射仪和扫描电镜分析了两种方法制备的TiO2粉体的形貌和晶体结构,并测定了纳米TiO2粉体对罗丹明B的光催化降解活性.结果表明:采用水热法制备的TiO2纳米粉体含有锐钛矿相和金红石相,粒径较小,大约为50nm,而且分散均匀,光催化性能良好;采用溶胶-凝胶法制备的TiO2粉体经过550℃煅烧后仍然为锐钛矿相,而且粒径较大,大约为80nm.     

超临界干燥法制备TiO2气凝胶

以钛酸四丁酯为原料,采用溶胶-凝胶过程及及超临界干燥法制备了TiO2气凝胶,并通过XRD,BET和TEM等方法对所得样品进行了表征.结果表明,该法制备的TiO2气凝胶具有很高的比表面积(488 m2/g),平均粒径为4.6nm,具有锐钛矿型晶体结构.经400℃煅烧2 h所得的纳米粉体,其锐钛矿型晶体结构更为明显,平均粒径6.7 nm,比表面积158 m2/g.     

溶胶-凝胶法制备(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3无铅压电陶瓷研究

锆钛酸钡钙基无铅压电陶瓷由于具有较好的压铁电性能且环境友好而备受研究者关注,但其存在烧结温度高(>1450℃)、居里温度低等缺点。为降低锆钛酸钡钙基压电陶瓷的预烧及烧结温度,并优化其电学性能,本研究采用溶胶-凝胶法成功合成了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃无铅压电陶瓷的前驱粉体,并在预烧温度为1000℃、烧结温度为1420℃时成功制备了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃陶瓷,相较于传统固相法,陶瓷的预烧温度降低了250℃,烧结温度降低了30℃,成功改善了陶瓷的烧结行为,得到了铁电性能、介电性能和压电性能优良且致密性良好的低温烧结陶瓷。     

Yb:Y_2O_3纳米粉体及陶瓷的制备和性能

以Y2O3和Yb2O3为原料,采用柠檬酸溶胶-凝胶法制备了Yb:Y2O3纳米粉体,将该粉体成型后在1500℃烧结7 h获得Yb:Y2O3陶瓷。XRD测试结果表明,Yb:Y2O3纳米粉体的合成温度为800℃。扫描电镜分析表明,Yb:Y2O3粉体的平均直径为40 nm左右。差热-热重分析表明,Yb:Y2O3纳米前驱粉体中柠檬酸和硝酸等在300℃左右分解。荧光光谱分析发现Yb:Y2O3陶瓷的最强荧光发射峰位于1030 nm,是Yb3+的2F7/2-2F5/2谱项导致的荧光发射。     

CaTiO3纳米粉体溶胶-凝胶法合成、表征及介电特性

采用无机盐溶胶-凝胶法制备了CaTiO₃纳米粉体，采用TG-DTA、XRD、TEM等技术进行了表征，并探讨了CaTiO₃纳米粉体烧结特性及介电效应。结果表明，干凝胶800 ℃低温煅烧可获得粒径分布较窄、平均粒径为60～70 nm的单相CaTiO₃纳米粉。纳米CaTiO₃粉具有较大的比表面积，使作为粉体烧结驱动力的表面能剧增，促使CaTiO₃在1 200 ℃实现致密烧结，比固相法制备的微米粉烧结降低100～200 ℃，且具有较宽的烧结温区。与微米级粉体烧结体介电特性相比，纳米粉具有更高的Q_f值。纳米CaTiO₃粉制备的陶瓷在1 250 ℃烧结2 h，获得优良的介电性能：ε_r=172，Q_f=4 239 GHz，τ_f=+7.68 × 10^-4 ℃^-1。     

预烧温度对CaO-Li_2O-Sm_2O_3-TiO_2微波介质陶瓷介电性能的影响

用固相反应法制备了CaO-Li2O-Sm2O3-TiO2(CLST)微波介质陶瓷。通过改变预烧温度(1 000~1 200℃)研究其对CLST微波介质陶瓷介电性能的影响。研究过程中,对预烧粉体与烧结陶瓷进行XRD与SEM分析,对陶瓷的介电性能εr、Q、τf进行了测试。结果表明,预烧温度对CLST微波介质陶瓷介电性能有较大影响,在预烧温度1 150℃,烧结温度1 340℃时可获得较好的介电性能:εr=112,Q=845,τf=52×10-6/℃。     

CaTiO3:Zn溶胶-凝胶法制备、结构及介电性能

采用溶胶-凝胶法制备了CaTiO3:Zn纳米粒子,透射电镜图显示平均粒径为25 nm.Zn的掺杂位置对于陶瓷相组成和烧结特性有很大影响.Ca1-xZnxTiO3和CaTiO3+zZnO样品的Zn以Zn2TiO4相形式存在;而CaZnyTi1-yO3-δy=0.01)样品中的Zn进入Ti位形成固溶体,无明显的降温效果,当Zn量增至0.05和0.1时,出现ZnO相.ZnO和Zn2TiO4第二相的存在均能明显促进陶瓷烧结.CaTiO3:Zn超细粉体可在较低温度下致密烧结(≤1 250 ℃).1 250℃烧结的CaZnyTi1-yO3-δ(y=0.01)陶瓷具有较好的介电性能:介电常数ε=157,品质因数Q×f=6 819 GHz,谐振频率温度系数(τ)f=7.51×10-4℃-1.     

锰掺杂Ba0.6Sr0.4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料, 采用草酸盐共沉淀法制备了钛酸锶钡（Ba0.6Sr0.4TiO3, BST）纳米粉体. XRD和SEM分析结果表明, 该方法制备出立方相的Ba0.6Sr0.4TiO3粉体, 平均粒径小于100 nm, 具有较高的烧结活性. 用传统固相法制备了锰掺杂钛酸锶钡-钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3, BST-MT)复相陶瓷, 系统研究了掺杂0.1%-2.0%(x, 摩尔分数, 下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理. 结果表明, 当锰的掺杂量小于1.5%时, Mn作为受主掺杂取代占据钙钛矿ABO3的B位, 因此导致居里点略微向高温偏移和相变扩散的发生, 锰的掺杂导致晶格畸变, 促进了晶粒生长, 使晶界相比例下降, 因此介电损耗随着锰掺杂量的增大而减小; 当锰的掺杂量为1.5%时, 介电损耗达到最小值, 继续增大掺杂量, 介电常数下降, 介电损耗上升.     

CaTiO3∶Zn溶胶-凝胶法制备、结构及介电性能

采用溶胶-凝胶法制备了CaTiO3∶Zn纳米粒子,透射电镜图显示平均粒径为25 nm。Zn的掺杂位置对于陶瓷相组成和烧结特性有很大影响。Ca1-xZnxTiO3和CaTiO3+zZnO样品的Zn以Zn2TiO4相形式存在;而CaZnyTi1-yO3-δ(y=0.01)样品中的Zn进入Ti位形成固溶体,无明显的降温效果,当Zn量增至0.05和0.1时,出现ZnO相。ZnO和Zn2TiO4第二相的存在均能明显促进陶瓷烧结。CaTiO3∶Zn超细粉体可在较低温度下致密烧结(≤1 250℃)。1 250℃烧结的CaZnyTi1-yO3-δ(y=0.01)陶瓷具有较好的介电性能:介电常数ε=157,品质因数Q×f=6 819 GHz,谐振频率温度系数τf=7.51×10-4℃-1。     

锰掺杂Ba0.6Sr0．4TiO3-MgTiO3复相陶瓷的制备和介电性能

以分析纯的Ba(NO3)2、Sr(NO3)2、草酸和钛酸丁酯为原料,采用草酸盐共沉淀法制备了钛酸锶钡(Ba0.6Sr0.4tiO3,BST)纳米粉体.XRD和SEM分析结果表明,该方法制备出立方相的Ba0.6Sr0.4TiO3粉体,平均粒径小于100 nm,具有较高的烧结活性.用传统固相法制备了锰掺杂钛酸锶钡.钛酸镁(Ba0.6Sr0.4TiO3-MgTiO3,BST-MT)复相陶瓷,系统研究了掺杂0.1%-2.0%(x,摩尔分数,下同)锰对钛酸锶钡-钛酸镁复相陶瓷微观形貌和介电性能的影响机理.结果表明,当锰的掺杂量小于1.5%时,Mn作为受主掺杂取代占据钙钛矿ABO3的B位,因此导致居里点略微向高温偏移和相变扩散的发生,锰的掺杂导致晶格畸变,促进了晶粒生长,使晶界相比例下降,因此介电损耗随着锰掺杂量的增大而减小;当锰的掺杂量为1.5%时,介电损耗达到最小值,继续增大掺杂量,介电常数下降,介电损耗上升.     

多环芳二酐型聚酯亚胺膜的透气性能

多环芳二酐型聚酯亚胺膜的透气性能李悦生，丁孟贤，徐纪平（浙江大学高分子科学与工程研究所，杭州，３１００２７）（中国科学院长春应用化学研究所）关键词聚醚酰亚胺，聚酯酰亚胺，膜，透气性通常的聚酰亚胺加工性能较差，在芳环二酐的苯环间引入醚键等柔性基团后，其...     

微量元素与疾病诊断治疗的研究现状及展望

对国内外微量元素与疾病的关系及其诊断治疗的研究现状及研究动向进行了综述，包括：微量元素与地方病、癌肿、心血管病、糖尿病、眼病、神经系统病等。参考文献72篇。     

Determination and study on residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil

A QuEChERS (quick, easy, cheap, effective, rugged, and safe) method for the determination of benazolin-ethyl and quizalofop-p-ethyl in rape and soil by high-performance liquid chromatography-tandem mass spectrometry has been developed in this study. The residue and dissipation of benazolin-ethyl and quizalofop-p-ethyl in rape and soil were determined with the developed method. The half-lives of benazolin-ethyl in rape straw and soil were 3.7–5.1 days and 14.3–26.3 days, respectively. The half-lives of quizalofop-p-ethyl in rape straw and soil were 5.0-6.1 days and 0.3–9.7 days, respectively. The residue of benazolin-ethyl and quizalofop-p-ethyl in rapeseed and soil were below the detection limit (i.e., 0.5?mg?kg^?1, the maximum residue level of European Union for quizalofop-p-ethyl).     

Synthesis and Optical and Redox Properties of Symmetric and Asymmetric BODIPYs

Herein, we present the synthetic route and the photophysical, electrochemical as well as laser properties of novel red‐emitting boron‐dipyrromethenes (BODIPYs) bearing arylethyne moieties. Such functionality is added along the main axis of the chromophore leading to single‐ and double‐substituted derivatives. The relationship between the dye structure and the lasing properties is studied in detail with the help of the photophysical and electrochemical properties as well as quantum mechanical simulations. The asymmetric substitution of the parent dye induces inhomogeneities in the charge distribution, which leads to an overall loss of the fluorescence capacity, mainly in polar media. Such non‐radiative deactivation processes can be softened by decreasing the electron‐donor ability of the substituent or even avoided by symmetrical substitution. Thus, grafting of the arylethyne moieties at the longitudinal axis of the indacene core results in an effective strategy to develop red‐edge BODIPYs with highly efficient and photostable laser emission.     

Ti-V基储氢合金及其氢化物的物相结构与组分优化设计

Ti-V基储氢合金在室温、常压下即可表现出良好的储氢特性,且质量储氢容量明显高于传统AB₅型储氢合金,从而在氢气的精制和回收、运输和储存及热泵等方面有较早的应用。 此外,在混合气体分离、核反应堆中处理氢的同位素、镍氢电池及燃料电池负极材料等方面也得到了广泛的研究与关注。 基于目前Ti-V基储氢合金的研究现状,概述了该类合金的优势、限制性因素(包括成因)及改性手段。 此外,为了进一步理解Ti-V基合金储氢机理、构建合金组分与储氢特性之间的对应关系,本工作重点围绕Ti-V基储氢合金及其氢化物的结构、组分优化设计展开综述,并对其未来研究方向做出展望。     

钒与糖代谢及糖尿病

微量元素钒作为生物体内必需元素，经证实有很重要的生理学功能，与机体糖代谢有十分密切的关系，且能降低糖尿病动物模型的高血糖，极有可能被开发为治疗糖尿病的药物。     

Conformations and steric and stacking interactions of trisubstituted ureas and thioureas with alkyl and phenyl groups

The monomeric ν(N—H) vibrations of various trisubstituted ureas of the R₂UPh type and -thioureas of the R₂TUPh type have been studied. The trans—out isomerism in the former and the trans—out—cis isomerism in the latter are discussed from the point of view of steric effect. The monomeric ν(N—H) vibrations of RPhUPh and RPhTUPh are also examined. The single band appearing in the spectrum of both ureas is characteristic of the cis form; this suggests the existence of phenyl—phenyl interaction (the stacking interaction proposed by Galabov et al. [10]). Behavior of ν(N—H) vibrations at several concentrations is shown to be clearly different in the three forms (trans, out and cis). The presence of the cis form is confirmed by solvent effect experiments.     

Synthesis of Tyrosol and Hydroxytyrosol Glycofuranosides and Their Biochemical and Biological Activities in Cell-Free and Cellular Assays

Tyrosol (T) and hydroxytyrosol (HOT) and their glycosides are promising candidates for applications in functional food products or in complementary therapy. A series of phenylethanoid glycofuranosides (PEGFs) were synthesized to compare some of their biochemical and biological activities with T and HOT. The optimization of glycosylation promoted by environmentally benign basic zinc carbonate was performed to prepare HOT α-L-arabino-, β-D-apio-, and β-D-ribofuranosides. T and HOT β-D-fructofuranosides, prepared by enzymatic transfructosylation of T and HOT, were also included in the comparative study. The antioxidant capacity and DNA-protective potential of T, HOT, and PEGFs on plasmid DNA were determined using cell-free assays. The DNA-damaging potential of the studied compounds for human hepatoma HepG2 cells and their DNA-protective potential on HepG2 cells against hydrogen peroxide were evaluated using the comet assay. Experiments revealed a spectrum of different activities of the studied compounds. HOT and HOT β-D-fructofuranoside appear to be the best-performing scavengers and protectants of plasmid DNA and HepG2 cells. T and T β-D-fructofuranoside display almost zero or low scavenging/antioxidant activity and protective effects on plasmid DNA or HepG2 cells. The results imply that especially HOT β-D-fructofuranoside and β-D-apiofuranoside could be considered as prospective molecules for the subsequent design of supplements with potential in food and health protection.     

Ferrocene and ferrocenium modified clays and their styrene and EVA composites

In this work, ferrocene- and ferrocenium-containing salts were employed to modify montmorillonite. X-ray measurements show an increase in the interlayer spacing upon clay modification, which means that the larger and more organophilic cations were inserted into the gallery space of montmorillonite. Attempts to prepare nanocomposites of polystyrene and ethylene vinyl acetate copolymers lead to immiscible systems; the morphology of these systems was elucidated with TEM, XRD and cone calorimetry. The thermal stability of the composites is greater than that of the virgin polymer.