湿法消解-差分脉冲溶出伏安法测定食品中总Cr

采用HNO3-H2O2消解-电化学方法测定小米中的铬含量。在DTPA-HAc-Na Ac体系中铬(Ⅵ)离子在镀汞电极上形成汞齐从而得到氧化峰电流,考察能够满足电化学测定的前处理消解技术。结果表明,铬(Ⅵ)离子的消解液在温度130℃,硝酸10 m L,过氧化氢38 m L,p H值呈中性时能够得到很好的电化学测定结果,线性相关系数为0.99,回收率为90%~110%。方法可以用于米中痕量铬(Ⅵ)的测定。     

新型高压湿法消解方法在食品检验中的应用

利用新型高压湿法消解前处理方法对普通食品 ,最佳消解条件为 12 0℃时 ,3h ,样品质量 /浓HNO3体积 /H2 O2 体积为 1∶3∶1。铅的回收率在 95 8%～ 10 4 5 % ,铜的回收率在 96 5 %～ 10 2 2 % ,其准确度完全能够满足食品中微量金属元素分析的要求。     

高压密闭消解-火焰原子吸收法测定核桃油中的铁和铜

主要利用钢衬F4高压密闭消解技术,分析样与硝酸-过氧化氢充分混合,设定梯度程序升温来分段优化油脂类复杂样品的前处理,消解后利用火焰原子吸收测定,具有分析样品量大,安全系数高,检出限低,低损耗,消解彻底等优点,适用于大批量样品同时测定和低含量样品的测定,Cu,Fe样品检出限为0.0028mg/L和0.0049mg/L,回收率97.54%—103.36%,Cu,Fe相对标准偏差（n=7）分别为0.8%,2.0%。     

食品中多种金属元素的同时测定-电感耦合等离子体质谱法

本工作利用硝酸-双氧水微波消解前处理法结合电感耦合等离子体质谱仪对食品中的15种金属元素进行同时测定。在微波消解仪的密闭高温高压条件下,经过酸体系消解食品中的金属元素完全释放出来,消解后的样品经过赶酸仪驱赶酸后,定容进行测定。在最佳实验条件下,测试了该方法的准确性、精密度及加标回收实验。实验结果表明各元素的曲线相关系数均在0.999以上,精密度和实际样品加标回收率均满足《实验室质量控制规范食品理化检测》(GB/T 27404-2008)中规定的要求。因此,该方法简单、快速,对食品中金属元素污染提供技术支撑,且对食品中金属元素污染控制方面具有重要的意义。     

分子印迹传感器对标本中塑化剂直接快速检测

本文构建了能够快速检测邻苯二甲酸二异壬酯(DINP)的分子印迹电化学传感器.首先利用分子印迹技术以热聚合的方法制备了分子印迹聚合物颗粒(MIPs);然后将优化的MIPs与琼脂糖溶液混匀固定在玻碳电极表面制备成DINP分子印迹电化学传感器;传感器可以特异性结合模板分子DINP且其电化学信号与DINP的浓度相关.再利用传感器检测样品中DINP的含量,检测过程不需要样本前处理,可以用于现场直接检测.该方法的线性方程为ΔI=0.03c+3.07,相关系数R~2=0.998,线性范围5×10~(-8)~1×10~(-6),mol/L,检测限为2.7×10~(-8),mol/L,在实际样品中的加标回收率为105.3%,~115.7%,.     

不同微波消解条件对聚氯乙烯中Cd、Cr、Hg、Pb测定结果的影响

通过同位素稀释质谱法（IDMS）及电感耦合等离子体质谱（ICP-MS）外标法,研究了不同微波消解酸体系对聚氯乙烯重金属含量测量结果的影响。实验结果表明,单一的硝酸及过氧化氢体系不能将PVC样品完全消解,消解之后样品底部有大量残渣剩余,ICP-MS外标法与IDMS方法数据有较大偏差;采用IDMS方法对样品以及消解后残渣进行分析,发现PVC中元素已经与稀释剂发生了同位素交换并趋于平衡,证明了IDMS方法的可靠性;采用硝酸、盐酸及过氧化氢的混合酸体系实现了样品的完全消解,对其消解后的溶液采用ICP-MS外标法进行元素检测,结果与IDMS方法一致;同时,延长消解时间对样品的消解也有一定的促进作用。     

微波消解-ICP-MS法同时测定食品用纸容器中15种元素

建立了电感耦合等离子体质谱(ICP-MS)结合微波消解测定食品用纸容器中15种元素的方法。试样经硝酸-过氧化氢混合溶液微波消解,ICP-MS测定,外标法定量。回收率在90%~120%之间,相对标准偏差均小于5%。该方法操作简便、灵敏度高,具有消解速度快、污染小、样品消解完全、回收率高的特点,适用于食品用纸容器中15种元素的同时分析。     

微波消解-ICP-AES法测定ABS塑料中的铅

建立微波消解-电感耦合等离子体原子发射光谱法测定ABS塑料中铅的含量为297.5 mg/kg.实验中消解体系为7.0 m L浓硝酸和1.5 m L30%过氧化氢,实验方法的检出限为7.35 mg/kg,精密度RSD5%,加标回收率为88.0%~107.0%.该方法样品用量少,溶样周期短,测试速度快,适用于ABS塑料中铅含量的快速测定.     

农产品中重金属检测技术发展

本文从样品前处理、分析检测技术等方面综述了农产品中重金属元素的分析方法。首先综述了样品前处理的方法,主要包括干法灰化法、湿法消解法、高压消解法和微波消解法;分析检测技术中,常规检测技术包括原子光谱法、电感耦合等离子质谱法,快速检测技术包括生物化学传感器、免疫分析法和电极法。为保障人民群众食用农产品安全,积极发展农产品中重金属元素检测技术和快速检测技术将是今后的重要发展方向。     

石墨炉原子吸收光谱法快速测定水产品中的铅

由于铅的危害极大,准确、快速测定水产品中铅含量有着重要的意义。通过部分消解样品和加入0.1%Triton X-100的方法处理样品达到直接进样的目的,采用石墨炉原子吸收光谱法测定水产品中铅元素含量。结果表明:在酸度为5%以下的溶液中以4u L0.2%硝酸钯做为基体改进剂,灰化温度为850℃,原子化温度为1 600℃,测定样品,铅浓度在0~20 ng/m L范围内,线性关系式为Y=0.020 8 X+0.009 1,相关系数为0.999 4。该方法的检出限为1.0 ng/m L,精密度为3.53%,准确度为2.50%,加标回收率101.39%~103.30%之间。该方法简单、快速、准确,节约成本,可以满足水产品中铅含量的测定。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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