Identification of Colorants in Food by Surface-enhanced Raman Spectroscopy and Wavelet-based Reverse Search

使用金纳米粒子为增强因子的表面增强拉曼光谱技术,通过连续小波变换将拉曼光谱信号转化到小波空间(墨西哥帽小波作为小波基)。该步骤能够减轻信号中基线; 变化及随机噪音的影响并找到峰位置和最佳小波尺度系数。依据小波空间中的信息,对混合物光谱及标准谱光谱进行反向搜索得到反向搜索匹配系数(Revere; match quality,; RMQ),作为判断混合物中目标成分是否存在的依据。该算法可对混合物中的目标物质进行准确定性,并已成功应用于多种食品中色素鉴定。食品中色素的检出率; 达到99%,且结果稳健,其效果明显优于传统的命中质量系数法(Hit quality index,; HQI)。这证实了小波空间反向搜索方法是一种快速而准确的拉曼光谱定性算法。In this study, a gold nanocrystal colloid was used as the enhancement; factor for surfaceenhanced Raman scattering (SERS). Raman spectra were; transformed by continuous wavelet transform (CWT),and Mexican hat; wavelet were chosen as the wavelet basis. This procedure could be used; to alleviate the influence of baseline variations and random noise,and; find peak positions and the best scale wavelet coefficients of signal.; Reverse search method was proposed to compare the spectrum of an unknown; sample with a spectrum of standard using the information in wavelet; space. Reverse match quality (RMQ) could be obtained automatically to; determine whether a substance is present. It was used to identify; colorants in a variety of food successfully. The colorants could be; identified with 99 percent accuracy. It shows a better performance; compared with traditional hit quality index (HQI). The study confirmed; that the wavelet-based reverse search is feasible and accurate in; qualitative analysis.国家自然科学基金资助项目; 国家重大科学仪器设备开发专

Acute Toxicity of Hg, Cd, Zn and Mn to Postlarvae of Penaeus japonicus Bate

在恒温(28±0.5℃)和充气条件下,研究了Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)对日本对虾仔虾的急性致毒效应.结果表明,Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)对日本对虾仔虾的毒性顺序为Hg--(2+)>Cd--(2+)>zn--(2+)>Mn--(2+).根据重金属对日本对虾仔虾的96HlC_(50)值计算的Hg--(2+)、Cd--(2+)、zn--(2+)、Mn--(2+)的安全浓度分别为0.0012、0.0342、0.0449、0.0950Mg/dM--3.The effects of acute toxicity of Hg2+, Cd2+, Zn2+ , Mn2+ under the condition of aeration postlarvae of Penaeus japonicus Bate have been studied at the temperature of 28±0.5℃.The results show that the order of toxicity of Hg2+, Cd2+ , Zn2+, Mn2+for postlarvae is Hg2+>Cd2+ >Zn2+>Mn2+.The "safe level" of Hg2+, Cd2+ , Zn2+ , Mn2+ to the larvae is 0.0012, 0.0342, 0.0449, 0.0950 mg/dm3 on the basis of the 96h LC50 value calculated for postlarvae

非点源污染研究中土壤溶解性无机氮的提取方法选择

用2M KCl溶液(5:1)、饱和CaSO4溶液(5:1)、0.01M CaCl2溶液(20:1,100:1) 和去离子水(20:1,100:1)4种提取液、6种提取方式,采用Auto-analyzerⅢColorimeter (Bran Luebbe),水杨酸-次氯酸盐法和Griess-Ilosvay法测定并对比了北京地区4种天然土样的溶解性氨氮和硝态氮的含量。研究结果表明:溶解性硝态氮的测定结果不受提取液和水土比(小于100:1)的影响,而溶解性氨氮测定结果受影响较大。在非点源污染研究中,对于土壤中可向水体迁移的溶解性无机氮含量的测定,应根据来水水源特征和研究目的选择适宜的浸提剂和水土比

界面能的尺度依赖性及其对界面断裂强度的影响

金属/陶瓷界面由于在催化转换、场效应晶体管、防腐蚀涂层和热势垒涂层等领域应用广泛而受到越来越多的关注。材料的失效和破坏往往首先发生在界面,因此界面能的研究具有重要意义。尤其随着电子器件的微型化,界面能的尺度效应不能忽略。本文通过同时考虑界面能的化学和结构贡献建立了金属/陶瓷界面能尺度效应的解

Interface energy and its influence on interface fracture between metal and ceramic thin films in nanoscale

A theoretical model about the size-dependent interface energy between two thin films with different materials is developed by considering the chemical bonding contribution based on the thermodynamic expressions and the structure strain contribution based on the mechanical characteristics. The interface energy decreases with reducing thickness of thin films, and is determined by such available thermodynamic and mechanical parameters as the melting entropy, the melting enthalpy, the shear modulus of two materials, etc. The predicted interface energies of some metal/MgO and metal/Al2O3 interfaces based on the model are consistent with the results based on the molecular mechanics calculation. Furthermore, the interface fracture properties of Ag/MgO and Ni/Al2O3 based on the atomistic simulation are further compared with each other. The fracture strength and the toughness of the interface with the smaller structure interface energy are both found to be lower. The intrinsic relations among the interface energy, the interface strength, and the fracture toughness are discussed by introducing the related interface potential and the interface stress. The microscopic interface fracture toughness is found to equal the structure interface energy in nanoscale, and the microscopic fracture strength is proportional to the fracture toughness. (C) 2010 American Institute of Physics. [doi:10.1063/1.3501090

Nano-size Effect of Interface Energy and Its Effect on Interface Fracture

An analytical model about size-dependent interface energy of metal/ceramic interfaces in nanoscale is developed by introducing both the chemical energy and the structure stain energy contributions. The dependence of interface energy on the interface thickness is determined by the melting enthalpy, the molar volume, and the shear modulus of two materials composing the interfaces, etc. The analytic prediction of the interface energy and the atomic scale simulation of the interface fracture strength are compared with each other for Ag/MgO and Ni/Al2O3 interfaces, the fracture strength of the interface with the lower chemical interface energy is found to be larger. The potential of Ag/MgO interface related to the interface energy is calculated, and the interface stress and the interface fracture strength are estimated further. The effect of the interface energy on the interface strength and the behind mechanism are discussed

一种垂直流人工湿地基质的制备方法

一种垂直流人工湿地基质的制备方法,其步骤是：A.选择原料：生物陶粒、沸石、 无烟煤、蛭石和钢渣；B.各原料粒径；C.各组合基质：所处理的污水特征污染物为 有机物时,基质为陶粒；所处理的污水特征污染物为氮时,基质为沸石；所处理的污水 特征污染物为磷时,有两种基质组合方式,其一：基质为无烟煤；其二：基质由上而下 依次为：无烟煤,蛭石,钢渣；所处理的污水为含有机物、氮和磷的综合污水时,基质 由上而下依次为：无烟煤,生物陶粒,沸石。方法简单,操作方便,能高效去除污水中 的特征污染物,污水经处理后,能达到《城镇污水处理厂污水排放标准》B标准,直接 回用或排入各水体中

EC-Pt/CNTs Glucose Oxidative Electrode

采用乙基纤维素(EC)和载Pt碳纳米管(CNTs)导电复合材料固定葡萄糖氧化酶(GOD)制备EC-Pt/CNTs葡萄糖氧化酶电极.该电极在0~4 mmol/L的浓度范围内检测葡萄糖,灵敏度为0.85μA/mmol.L-1,浸泡18 d后电极活性仍达80%,EC-Pt/CNTs葡萄糖氧化酶电极可望构建葡萄糖传感器.A glucose oxidative electrode(GOD),EC-Pt/CNTs glucose oxidative electrode,was constructed by ethyl cellulose(EC) and Pt/CNTs.The sensitivity of the EC-Pt/CNTs GOD is 0.85 μA/mM in the concentration range of 0～4 mmol/L of glucose.After dipped in PBS(4℃) for 18 days,the activity of the EC-Pt/CNTs GOD can reach 80%.It is promising for the EC-Pt/CNTs GOD to be used to construct glucose biosensor.作者联系地址：华南理工大学化学与化工学院;Author's Address: School of Chemistry and Chemical Engineering,South China University of Technology,Guangzhou 510640,Chin