A strategy for constructing sensitive and renewable molecularly imprinted electrochemical sensors for melamine detection

A novel strategy for preparing highly sensitive and easily renewable molecularly imprinted polymer (MIP) sensors was proposed. Using melamine (MA) as the template molecule, MIP particles were synthesized and embedded in a solid paraffin carbon paste to prepare the MIP sensor. MA was indirectly determined from the competition between the reactions of MA and horseradish peroxidase-labeled MA (MA-HRP) with the vacant cavities. The detection signals were amplified because of enzymatic reaction to the H₂O₂ catalytic oxidation. Sensitivity was markedly improved. Sensor renewal was achieved by a simple mechanical polishing of the sensitive film. The linear range for MA detection was 0.005–1 μmol L⁻¹ and the detection limit was 0.7 nmol L⁻¹. The molecularly imprinted solid paraffin carbon paste sensor was used for MA detection in milk samples.     

Molten solvent extraction behavior of palladium with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone at 60 °C

The solvent extraction behavior of precious metal palladium with 1-phenyl-3-methyl-4-benzoyl-5-pyrazone (PMBP) into molten paraffin wax has been studied in the temperature range from 55 to 75 °C. The complex consisting of PMBP and palladium was extracted into molten wax phase in the pH range from 1.0 to 3.5 at 60 °C. The extraction efficiency was up to 97% at the experimental pH. The stoichiometry of the extracted species of palladium was determined on the basis of slope analysis method. The effects of time to achieve equilibrium, temperature, and extractant concentration on the extraction were discussed. The thermodynamic data indicate that the extraction is an endothermic reaction and the increase of temperature promotes the extraction of palladium into molten paraffin wax and the extraction of palladium with PMBP is entropy controlled at high temperatures.      

含纳米银有机流体的制备及其摩擦学性能研究

采用溶剂萃取法将银离子转移到有机相并直接还原，制备了稳定的含纳米银有机流体；采用傅立叶红外光谱仪和透射电子显微镜等表征了有机流体中的纳米银微粒；采用MMW-1型立式摩擦磨损试验机考察了含纳米银液体石蜡的摩擦学性能．结果表明，萃取剂对纳米银微粒具有良好的表面修饰作用；纳米银微粒可以有效地改善液体石蜡的减摩抗磨性能；纳米银质量分数为0．1％的液体石蜡的减摩性能最佳；所采用的制备方法工艺简单，可望用于含纳米微粒的有机流体和润滑油的规模化制备。     

离子色谱法测定氯化石蜡中的总氯量

采用氧瓶燃烧法处理氯化石蜡样品,用离子色谱测定吸收液中Cl^-的方法来确定氯化石蜡的总氯量。在Metrosep A SUPP5型阴离子分离柱上,以3．2mmol／LNa2CO3和1．0mmol／LNaHCO3混合溶液作为淋洗液,抑制型电导检测,检出限为0．87μg／L,线性范围0．1—4mg／L,相对标准偏差与回收率分别为1．71％～2．14％、94．4％-103．1％。该方法简便、快速,结果与国家标准法比较无显著性差异。     

延长Rb原子退相干时间镀膜材料的可行性研究

实验测量了镀石蜡Rb池和石英玻璃Rb池中Rb原子自旋态寿命.研究表明,镀石蜡Rb池的Rb原子自旋态寿命在温度T=50℃约为7ms,而在同样温度的石英玻璃池中,Rb原子自旋态寿命仅为20μs.这为基于自旋的量子存储实验提供了很好的借鉴.同时讨论了其他候选的材料来隔绝碱金属原子和容器壁的非弹性碰撞相互作用.根据实验结果,我们认为H原子布于笼状结构内部的C60H60以及BN材料有较大的实用前景.     

Electroluminescence and N2 laser excited fluorescence of high field electroformed castor oil and liquid paraffin

The method of preparation of electroluminescent (el) cells using dielectric liquids like castor oil and liquid paraffin by an electroforming process is presented. Theel spectrum of the material derived from castor oil exhibits a large number of sharp lines which can be grouped into four distinct series superposed on a broad background. Theel spectrum of liquid paraffin cells does not show any significant line features. The N₂ laser excited fluorescence spectra of these oils and of the respective electroformed materials are also recorded. The electrical and brightness characteristics of these cells are discussed in detail.     

热管式相变蓄热换热器储/放能过程中传热特性的实验研究

将热管作为换热元件应用于相变蓄热系统中,研制了一套热管式相变蓄热换热器。采用石蜡作为蓄热材料,对其储、放能过程即内部石蜡的融化与凝固过程进行了实验研究。测定了储、放能过程中不同时刻换热器内石蜡的温度分布; 改变供、取热流体参数,分析了供/取热流体的入口温度与流量对换热器储/放能过程的影响;分析了储、放能过程中能量随时间的变化情况。结果表明,热管在本换热器内极好地发挥了换热元件的作用,换热器运行状况良好,各项功能均能较好地实现。     

Experimental study on the heat transfer characteristics of a new type flat micro heat pipe heat exchanger with latent heat thermal energy storage

An experimental energy storage system has been designed using a new type flat micro heat pipe heat exchanger that incorporates a moderate-temperature phase change material paraffin with a melting point of 58°C. The basic structure, working principles, and design concept are discussed. The heat transfer process during the charging and discharging of the heat exchanger under various operating conditions has been experimentally investigated. Results show that the performance of the new type flat micro heat pipe was steady and efficient during charging and discharging. The average thermal storage power and absorption efficiency have been determined to be approximately 537 W and 92.5%, respectively.     

Grid-shell theory,a new concept to explain thixotropy

Some rheological phenomena of the thixotropic pseudoplastic crude oils can not be accounted for by the earlier theories: e.g. stabilized hysteresis curve, no regeneration during motion, irreversible change of paraffin structure by shearing, anisotropic network after relaxation, influence of shear history on flow properties. The grid-shell theory seems to be adequate to interpret these characteristics.