熔盐电解后处理工艺中的在线监测技术

干法后处理技术是我国核燃料循环体系的重要发展方向,其中有发展前景的熔盐电解法在工业化过程中需要对元素进行准确地监测以保障安全运行。传统离线检测方法程序复杂、数据分析延迟,而在线监测方法因可以获得实时数据而备受瞩目。本文对近几年国内外熔盐电解法中不同元素的在线监测技术进行了总结,重点调研分析了电化学法中的循环伏安法、安培法、脉冲法以及光谱法中的荧光光谱法和紫外光谱法在各种元素的在线监测中的原理、特点和应用前景,以期对熔盐电解中在线监测技术的研发和实际应用提供理论支撑和技术参考。     

高温高压处理钻石的谱学特征综述

综述了近年来高温高压处理钻石的成果。该处理方法的对象主要有天然钻石、高温高压合成钻石以及化学气相沉淀法合成钻石。系统地总结和分析了该类处理钻石的谱学特征,包括紫外-可见光吸收光谱、红外吸收光谱、拉曼光谱、光致发光光谱及荧光特征,提供了其主要的鉴定依据。     

荔枝核提取物抗氧化活性及红外光谱特性

以荔枝核为原料,以95％的乙醇为提取剂,在超声波的作用下得到荔枝核乙醇提取物。利用提取物对DPPH自由基和羟自由基的清除能力评价其抗氧化活性;同时测定了提取物的总还原能力和总的抗氧化性。最后通过红外光谱对提取物进行了定性分析。实验结果表明：荔枝核提取物具有很强的抗氧化活性,其抗氧化能力大5-BHT,小于维生素C;荔枝核提取物清除DPPH·和·OH的IC50分别为0．032、0．160mg／mL。每克荔枝核提取物总抗氧化能力相当于210mgVc的总抗氧化能力：从红外光谱的结果可知,荔枝核提取物主要为黄酮类物质。     

Multilayer assembly of ionic starches on old corrugated container recycled cellulosic fibers

In this study, old corrugated container recycled fibers were treated with polyelectrolyte multilayers consisting of biopolymer cationic starch with two degrees of substitution (DS) each in combination with one anionic starch. Pulp zeta potential, paper strength and the thin layer ellipsometry technique were applied to examine the influence of cationic starch DS on the formation of polyelectrolyte multilayers. The results indicated a significant interaction between the DS of cationic starch and the number of ionic starch layers formed. When low‐DS cationic starch was used, the pulp zeta potential and the paper strength increased significantly in assembling the first cationic layer. However, in depositing high‐DS cationic starch a greater zeta potential and a stronger influence on the paper strength were observed with a larger number of starch layers. This was confirmed by thin layer ellipsometry when a greater thickness of multilayers was achieved by employing high‐DS cationic starch to form a higher number of layers. © 2017 Society of Chemical Industry     

Tris(dithiocarbamato)iron(III) complexes as precursors for iron sulfide nanocrystals and iron sulfide-hydroxyethyl cellulose composites

Iron(III) complexes of dimethyldithiocarbamate and imidazolyl dithiocarbamate were synthesized and characterized by elemental analyses, FTIR, UV–VIS and the ligands by NMR spectroscopy. The complexes were thermolysed as single molecule precursors at 180°C to prepare octadecylamine (ODA) capped iron sulfide nanocrystals and iron sulfide-hydroxyethyl cellulose (HEC) composites. UV–VIS, PL, FTIR, P-XRD, HRTEM, FESEM and EDS were used to characterize the iron sulfide nanocrystals and corresponding HEC nanocomposites. XRD confirmed iron sulfide nanocrystal (NP1) from dimethyldithiocarbamate to be hexagonal pyrrhotite-5H, Fe₉S₁₀ crystalline phase while iron sulfide nanocrystals (NP2) from imidazolyl dithiocarbamate is in pyrrhotite, Fe₁₁S₁₂ crystalline phase. TEM images show that the iron sulfide nanocrystals have particle sizes in the range 24–32?nm for NP1 and 18–25?nm for NP2 iron sulfide nanocrystals. The optical band gaps of the iron sulfide nanocrystals obtained from Tauc plots are 3.83 and 4.16?eV for NP1 and NP2, respectively. IR spectra, FESEM surface morphology and EDS spectra of iron sulfide/HEC composites confirmed dispersion of the iron sulfide nanocrystals within the hydroxyethyl cellulose (HEC) matrix.     

Oxoiron(V) Complexes of Relevance in Oxidation Catalysis of Organic Substrates

The selective oxidation of alkane and olefin moieties are reactions of fundamental importance in both chemical synthesis and biology. Nature efficiently catalyzes the oxidation of hydrocarbons using iron-dependent enzymes, which operate through the mediation of oxoiron(IV) or oxoiron(V) species. In the quest for chemo, regio and stereoselective transformations akin to those taking place in nature, bioinspired iron catalysts have been developed and understanding their mechanism of action has become a particularly relevant area of research. While a prominent advance in the preparation and characterization of oxoiron(IV) species has been accomplished, oxoiron(V) species remain exceedingly rare, presumably because the high reactivity that makes them particularly interesting also makes them difficult to observe. This review summarizes the advances in the field, focusing in synthetic systems for which the oxoiron(V) species relevant in these transformations have been directly detected and spetroscopically characterized.     

Electrochemical Impedance Spectroscopic Analysis of Sensitization-Based Solar Cells

Electrochemical impedance spectroscopy (EIS) is a very powerful tool for elucidation of charge transfer and transport processes in sensitization-based solar cells (e.g., dye-sensitized solar cells [DSSCs], quantum dot-sensitized solar cells [QDSSCs], and perovskite solar cells [PSCs]). EIS measures the electrochemical response to small amplitude AC signals over a wide range of frequencies. Analysis of the EIS response provides information about the corresponding parameters of the cells. Here, we review the fundamentals of EIS, charge transport kinetic processes, and equivalent circuit models of sensitization-based solar cells and use these concepts to explain the EIS spectra of DSSCs, QDSSCs, and PSCs. This review will be very useful for understanding the fundamental charge transfer and transport processes in different sensitization-based solar cells and the use of an equivalent circuit model to interpret the observed charge transfer and reactions.     

Improved preservation of phospholipid-rich multilamellar bodies in conventionally embedded mammalian lung tissue—an electron spectroscopic study

Different conventional methods of tissue processing were studied to determine the extent to which phospholipid-rich multilamellar bodies of pulmonary alveolar epithelial type II cells of the pig were preserved. Prolonged treatment with half-saturated aqueous uranyl acetate yielded excellent results on the stabilization of the multilamellar substructure, irrespective of whether glutaraldehyde-paraformaldehyde or glutaraldehydetannic acid was used as a primary fixative. The lamellar periodicities were observed to be 5·5–6·1 nm. Differences in the phosphorus distribution among several types of lipid bodies of alveolar epithelial type II cells were studied by means of electron spectroscopic imaging and electron energy-loss spectroscopy. Multilamellar bodies gave phosphorus signals which were significantly higher than those obtained from granular regions of composite bodies, whereas homogeneous bodies gave phosphorus signals which were even lower than those obtained from mitochondria, endoplasmic reticulum membranes or ribosomes.     

柴油机油液光谱分析中消除换油干扰的方法研究

柴油机机油中金属元素的成分和含量的变化蕴涵着各摩擦副润滑、磨损和工作状态的丰富信息，但是，柴油机运转过程中的频繁换油影响了元素浓度变化的趋势。通过对换油后Fe浓度曲线进行线性回归，在系统中排除了换油后的浓度变化的影响，从而为柴油机的磨损趋势和故障趋势的研究提供了保证。     

Optimal strategies for imaging thick biological specimens: exit wavefront reconstruction and energy-filtered imaging

In transmission electron microscopy (TEM) of thick biological specimens, the relationship between the recorded image intensities and the projected specimen mass density is distorted by incoherent electron–specimen interactions and aberrations of the objective lens. It is highly desirable to develop a strategy for maximizing and extracting the coherent image component, thereby allowing the projected specimen mass density to be directly related to image intensities. For this purpose, we previously used exit wavefront reconstruction to understand the nature of image formation for thick biological specimens in conventional TEM. Because electron energy-loss filtered imaging allows the contributions of inelastically scattered electrons to be removed, it is potentially advantageous for imaging thick, biological samples. In this paper, exit wavefront reconstruction is used to quantitatively analyse the imaging properties of an energy-filtered microscope and to assess its utility for thick-section microscopy. We found that for imaging thick biological specimens (> 0.5 μm) at 200 keV, only elastically scattered electrons contribute to the coherent image component. Surprisingly little coherent transfer was seen when using energy-filtering at the most probable energy loss (in this case at the first plasmon energy-loss peak). Furthermore, the use of zero-loss filtering in combination with exit wavefront reconstruction is considerably more effective at removing the effects of multiple elastic and inelastic scattering and microscope objective lens aberrations than either technique by itself. Optimization of the zero-loss signal requires operation at intermediate to high primary voltages (> 200 keV). These results have important implications for the accurate recording of images of thick biological specimens as, for instance, in electron microscope tomography.