离子液体双水相微波辅助萃取姜黄中姜黄素

以亲水性离子液体溴化N-丁基吡啶([BPy]Br)和磷酸氢二钾形成的双水相体系结合微波辅助萃取姜黄中姜黄素类化合物,在波长424.5nm处测量其吸光度,提出了紫外分光光度法测定姜黄素类化合物总量。通过正交试验对离子液体双水相微波辅助提取姜黄中姜黄素的条件进行了试验,得到最佳提取条件:料液比为0.015比1,微波功率为320W,提取时间为120s,磷酸氢二钾用量为7.0g。在此条件下,姜黄素的提取率达4.99%,比传统热回流提取的提取率(0.042%)高100多倍。     

双掺杂锰酸钙基热电陶瓷的制备及电学性能研究

利用传统固相反应法成功制备出Nb掺杂量x不同的Ca_0.9Yb_0.1Mn_1-xNb_xO₃热电陶瓷. X射线衍射分析和扫描电子显微镜分析表明: 样品均形成了单一的钙钛矿正交结构,空间群为Pnma. 晶格常数a和晶胞体积随着Nb掺杂量x的增加而增大,陶瓷样品具有很好的结晶度和很高的致密性, 相对密度达到97%左右. 在3 关键词： 3陶瓷')" href="#">CaMnO₃陶瓷 电阻率 Seebeck系数     

烧结温度对La0.9Sr0.1FeO3热电性能的影响

利用传统的固相反应分别在1250℃,1300℃,1350℃.烧结条件下制备出钙钛矿结构的La_0.9Sr_0.1FeO₃陶瓷样品.样品的XRD粉末衍射结果显示不同烧结温度的La_0.9Sr_0.1FeO₃陶瓷样品都是单相的正交结构,同时晶胞体积随着烧结温度的升高而减小.从样品的SEM结果看出,随着烧结温度的升高,晶粒逐渐变大,并且晶粒间的空隙逐渐减小,样品更加致密.在室温到800℃的 关键词： 铁酸镧陶瓷 热电性能 烧结温度     

Nonlinear Electrical Characteristics of Antimony and Copper Doped Tin Oxide Based Varistor Ceramics

The novel CuO-doped dense tin oxide varistor ceramics are investigated. The densification of tin oxide varistor ceramics could be greatly improved by doping copper oxide additives. The introduction of antimony additives into a SnO2. CuO ceramic system would make it possess excellent nonlinearity. The sample doped with 0.05 mol% Sb2 03 possesses the highest nonlinearity coefficient （α = 17.9） and the lowest leakage current density （ JL = 52μA cm^-2） among all the samples. A modified defect barrier model is introduced to explain the formation of the grainboundary barrier. The nonlinear behaviour of （Cu, Sb）-doped SnO2 varistor system could be explained by the barrier model.     

(Sr,Co,Nb)掺杂SnO2压敏电阻的电学非线性

研究了Sr对新型(Co, Nb)掺杂SnO2压敏材料微观结构和电学性质的影响.当SrCO3的含量从零增加到1.50mol%时,(Co, Nb)掺杂SnO2压敏电阻的击穿电压从240V/mm猛增到1482V/mm.样品的微观结构分析发现, 当SrCO3的含量从零增加到1.50 mol%时, SnO2的晶粒尺寸迅速减小.晶界势垒高度测量揭示,SnO2晶粒尺寸的迅速减小是击穿电压急剧增高的主要原因.对Sr含量增加引起SnO2晶粒减小的根源进行了解释.掺杂1.50 mol% SrCO3的SnO2压敏电阻非线性系数为21.4,击穿电压高达1482V/mm.     

纸基质室温磷光法快速测定中药材中西维因的研究

以快速定量滤纸为基质,用KI作为重原子微扰剂,建立了快速测定中药材中西维因的固体基质室温磷光(SS-RTP)分析法。其最大激发和发射波长分别为284nm与520nm。在优化的实验条件下,西维因在4×10-6~2×10-4mol/L浓度范围内呈现良好的线性关系。在样品体积为10μL时,方法的检出限为0.89ng/斑点。所建立的方法用于中草药中西维因残留量的测定。     

Strategies for optimizing the thermoelectricity of PbTe alloys

The thermoelectric materials have been considered as a potential candidate for the new power generation technology based on their reversible heat and electricity conversion.Lead telluride(Pb Te) is regarded as an excellent mid-temperature thermoelectric material due to its suitable intrinsic thermoelectric properties.So tremendous efforts have been done to improve the thermoelectric performance of Pb Te,and figures of merit,z_T 2.0,have been reported.Main strategies for optimizing the thermoelectric performance have been focused as the main line of this review.The band engineering and phonon scattering engineering as two main effective strategies are systemically summarized here.The band engineering,like band convergence,resonant levels,and band flatting have been addressed in improving the power factor.Additionally,phonon scattering engineerings,such as atomic-scale,nano-scale,meso-scale,and multi-scale phonon scatterings have been applied to reduce the thermal conductivity.Besides,some successful synergistic effects based on band engineerings and phonon scatterings are illustrated as a simultaneous way to optimize both the power factor and thermal conductivity.Summarizing the above three main parts,we point out that the synergistic effects should be effectively exploited,and these may further boost the thermoelectric performance of Pb Te alloys and can be extended to other thermoelectric materials.     

固相(微)萃取-室温磷光联用技术及其应用

综述了固相(微)萃取-室温磷光技术的主要方法以及在环境分析中的应用。主要从固相萃取的基本原理、装置、操作步骤、分离模式及填料等方面评述了固相(微)萃取技术的特点和应用,评述了室温磷光技术的优点和经典室温磷光技术在操作方法和定量分析方面存在的不足,提出了固相(微)萃取和室温磷光联用技术的必然性及其优点,并对该方法的关键技术和存在的难题进行了分析。该技术结合了富集技术与高选择性的磷光分析方法,使得分析的灵敏度进一步提高,选择性也得到了较大的改进。目前常用的固相萃取填料主要有Whatman 1PS滤纸和填充有C₁₈或C₈盘或(膜),目标分析物主要集中在多环芳烃、多氯联苯和多氯联苯呋喃等物质的分析,应用前景十分广泛。     

荧光光度法测定槐花中槲皮素

研究了基于槲皮素和铝的络合反应来测定槲皮素的荧光光度法,试验结果表明:铝与槲皮素的配合物在pH 9.15的BR缓冲溶液中进一步与BO3-3形成三元体系,在452 nm激发波长下,于516 nm发射波长处测定其荧光强度,槲皮素浓度在1.0×10-7～6.0×10-6mol·L-1范围内配合物的荧光强度与槲皮素的浓度呈线性关系,检出限(3S/N)为2.1×10-7mol·L-1.该方法用于槐花提取物中槲皮素的测定,并以实样为基体用标准加入法做了回收试验,测得回收率在101.5%～112.5%之间.     

Nb掺杂对还原性烧结的TiO2-δ陶瓷的晶体结构及热电性能的影响

利用传统的固相反应法在还原性气氛1200 ℃下分别制备出不同Nb掺杂量的Ti_1-xNb_xO_2-δ陶瓷样品.样品的粉末X射线衍射(XRD)结果显示:Nb掺杂量x较低时样品为多相混合,当Nb掺杂量x>0.02时样品为单一的四方相金红石型结构.在室温到900 K的测试温区,测试了单相样品(x=0.02,0.03,0.04)的电导率、Seebeck系数和热导率.测试 关键词： 氧化钛陶瓷 热电性能 氧空位