Full-Wave Analyses for a Multi-Layered Microstrip Patch Antenna

This paper describes numerical modelling of a dual band multi-layered microstrip patch antenna operating at 35GHz on an in-house semi-insulating GaAs substrate. The simulated and measured resonant frequencies at both lower and upper resonant frequencies will be compared to check the accuracy of the different numerical modelling techniques.     

Towards advanced circuit board materials: adhesion of copper foil to ultra‐high molecular weight polyethylene composite

Polyethylene based composites are attractive materials for advanced circuit board applications because of their unique combination of properties: low dielectric constant and loss factor, light weight, high flexural modulus and low thermal expansion coefficient controlled in all spatial directions. This investigation describes a process to consolidate chopped fibers of ultra‐high molecular weight polyethylene concurrently with its bonding to a copper foil. Bonding is affected by a thin sheet of low‐density polyethylene, incorporating a crosslinking agent with a concentration gradient across the sheets thickness. In this single step process, the composite material is formed and bonded to the metal foil, achieving good adhesion without the use of extraneous glue. Copyright © 2002 John Wiley & Sons, Ltd.     

QuEChERS/超高效液相色谱-串联质谱法同时测定水产品中四溴双酚A与六溴环十二烷

建立了同时测定水产品中四溴双酚A(TBBPA)和六溴环十二烷(HBCD)的超高效液相色谱-串联质谱方法。样品前处理采用QuEChERS方法,均质生物样品用水分散后加乙腈提取,经C_(18)分散固相萃取净化。采用CORTECS~?C_(18)色谱柱(4.6 mm×100 mm×2.7μm)分离,以甲醇-水为流动相进行梯度洗脱,流速为0.7 mL/min。采用电喷雾离子源,在负离子模式下以多反应监测(MRM)方式检测。结果表明,TBBPA和3种HBCD单体在0.5～500μg/L范围内线性良好,相关系数(r)大于0.998,检出限(LOD,S/N=3)和定量下限(LOQ,S/N=10)分别为0.04～0.16μg/kg和0.12～0.55μg/kg。在5、20、50μg/kg加标水平下的平均回收率为74.0%～121%,相对标准偏差(RSD)为0.20%～23%。该方法操作简单、快速、重现性好,适用于水产品中TBBPA和HBCD的快速检测。     

水合醋酸铈直接热分解制备超细氧化铈及其抛光性能

Ultra fine ceria was prepared by calcining hydrate cerium acetate. The effects of pyrolysis temperature on the particle size, morphology, specific surface area and loose packing density of ceria were investigated, and the removal rate of optical glasses polishing by ceria was determined. The results show that with the increase of pyrolysis temperature, the loose deposit density and crystallinity increases and the specific surface area decreases, however, the particle size decreases firstly and then increases, the minimum medium particle size D₅₀ is 0.47 μm at pyrolysis temperature of 1 000 ℃. The SEM images of ceria prepared by the decomposition at 800 ℃ or at 1 100 ℃ show porous powders or quasi-sphere small particles with loosely agglomeration, respectively. It was found that the removal rate varied with pyrolysis temperature in preparation of ceria and the property of glass polished. The removal rate for three kinds of glasses was in the order of ZF7> F1> K9, and the maximum value appeared at around 1 000 ℃ for ZF7 and F1, and at around 1 100 ℃ for K9.     

Fermentation characteristics and the dynamic trend of chemical components during fermentation of Massa Medicata Fermentata

As a representative of traditionally fermented Chinese medicine, Massa Medicata Fermentata (MMF) shows the functions of invigorating the spleen and stomach and promoting digestion, which plays an important role in the treatment of gastrointestinal diseases. The fermentation mechanism and the key factors that affect the quality of MMF have not been revealed yet, which has become an urgent issue that limits its clinical application. This article aims to systematically and comprehensively reveal the transformation of physical properties and the dynamic trend of chemical components including substrate components, volatile components, and lactic acid as anaerobic fermentation product during MMF fermentation. Along with obvious hyphae growth observed for MMF, the weight of MMF decreased, and the moisture and temperature increased. Through the quantified 14 components from substrate, ferulic acid increased from 45.53 ± 6.94 to 141.89 ± 78.40 μg/g, while glycosides and phenolic acids declined except caffeic acid. Also, within the 66 volatile components analyzed, alcohols and acids increased, while aldehydes and ketones decreased. Lactic acid was not detected in the fermentation substrate, but an apparent increase in lactic acid content was observed along with the increased fermentation days, resulting in 2.54 ± 0.15 mg/g on day 8. Based on the tested components, the fermentation process of MMF was discriminated into three distinct stages by principal component analysis, and an optimal fermentation time of four days was proposed. The results of this study will be of great significance to clarify the characteristics of fermentation and conduce to improving quality standards of MMF.     

溶剂萃取法制备Co(PO_3)_2超细微粉

本文用溶剂萃取法成功地制备了偏磷酸钴超细微粉并通过ＸＲＤ，ＩＲ，ＴＧ，ＤＴＡ，ＴＥＭ等实验对超细微粉的组成、结构进行了表征。     

卟啉超分子化合物在分子器件中的应用

分子电子器件已成为近年来的一个研究热点，卟啉类化合物因为光敏性好、性能稳定、易于修饰等优点成为分子器件研究的理想模型化合物。本文着重介绍了它在分子器件中的最新应用进展。     

Trace Detection of Mercury(II) Using Gold Ultra‐Microelectrode Arrays

The electroanalytical detection of trace mercury(II) at gold ultra‐microelectrode arrays is reported. The arrays consist of 256 gold microelectrodes of 5 μm in diameter in cubic arrangements which are separated from their nearest neighbor by 100 μm. The array was utilized in nitric acid using linear sweep voltammetry where a linear response from mercury additions over the range 10 μg L^?1?200 μg L^?1 (10^?8?10^?6 M) was observed with a sensitivity and detection limit of 0.11 nC/μg L^?1 and 3.2 μg L^?1 (16 nM) respectively from using a deposition time of 30 s at ?0.2 V (vs. SCE). This methodology was explored in 0.1 and 1 M chloride media over the mercury range 10 μg L^?1?200 μg L^?1 (5×10^?8?10^?6 M) where similar sensitivities of 0.087 nC/μg L^?1 and 0.078 nC/μg L^?1 were observed with an identical detection limit. The protocol is demonstrated to be useful for the determination of mercury for analysis of environmental water samples.     

无机阴离子的毛细管电泳分析

本文研究了常见无机阴离子的毛细管电泳规律，考察了分离电压、电解质熔液组成、浓度、ｐＨ值等对分离的影响，建立了高效、快速的无机阴离子毛细管电泳分析方法。在选定的实验条件下，各种常见无机阴离子在５ｍｉｎ内达到完全分离，对Ｂｒ＾－和Ｃｌ＾－的分离柱效每米可达７６万理论板数。迁移时间的相对标准偏差小于１％，峰面积的相对标准偏差小于５％，各离子的最低检测浓度为０．０５￣０．５μｇ／ｍｌ。     

分散固相萃取净化-超高效液相色谱-串联质谱法同时测定鱼和虾中抗生素及三苯甲烷类兽药残留

建立了分散固相萃取净化-超高效液相色谱-串联质谱法快速测定鱼和虾中3类（磺胺类、喹诺酮类、氯霉素类）18种抗生素及2种三苯甲烷类（孔雀石绿、隐色孔雀石绿）兽药残留。样品经磷酸氢二钾溶液水解分散，乙腈提取，提取液经氯化钠脱水、盐析后取乙腈层，经旋转蒸发仪浓缩至近干，残留物用甲醇定容至1.0 mL，C18和PSA（N-丙基乙二胺）填料分散固相萃取净化，过滤膜后经ZORBAX C18色谱柱（50 mm×2.1 mm，1.8 μm）分离，正、负离子多反应监测模式采集数据，同位素内标法定量。实验结果表明，20种兽药在0.2~300 μg/L范围内具有良好的线性关系，检出限为0.1~0.6 μg/kg，定量限为0.3~1.8 μg/kg，相关系数均大于0.99。在1、5和20倍定量限加标浓度水平下，平均回收率为72.5%~118%，相对标准偏差（RSD）为1.9%~9.8%。该方法具有前处理简单、检测效率高、成本低等优点，适用于鱼和虾中多类兽药残留的同时测定。