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Investigations on the degradation of aspartame using high-performance liquid chromatography/tandem mass spectrometry

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Chinese Chemical Letters 2014年第9期25卷 1259-1264页

作者： Jie-Ping Sun Qiang Han Xiao-Qiong Zhang ming-yu ding Beijing Key Laboratory for Microanalytical Methods and Instrumentation Department of ChemistryTsinghua University

Aspartame is a widely used sweetener, the long-term safety of which has been controversial ever since it was accepted for human consumption. It is unstable and can produce some harmful degradation products under certain storage conditions. A high-performance liquid chromatography/tandem mass spectrometry method was developed for the simultaneous analysis of aspartame and its four degradation products, including aspartic acid, phenylalanine, aspartyl-phenylalanine and 5-benzyl-3,6- dioxo-2-piperazieacetic acid in water and in diet soft drinks. Aspartame and its four degradation products were quantified by a matrix matched external standard calibration curve with excellent correlation coefficients. The limits of detection were 0.16-5.8 μg/L, which exhibited higher sensitivity than common methods. This method was rapid, sensitive, specific and capable of eliminating matrix interferences. It was also applied to the study of the degradation of aspartame at various pH and temperatures. The results indicated that aspartame was partly degraded under strong acidic or basic conditions and the extent of degradation increased with increasing temperature.

关键词： High-performance liquid chromatography/tandem mass spectrometry Aspartame Degradation productsCola

Determination of uric acid in human urine by ion chromatography with conductivity detector

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Chinese Chemical Letters 2011年第3期22卷 342-345页

作者： Fu Yong Zhao Zong Hua Wang Hui Wang Rui Zhao ming yu ding Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education) Department of Chemistry Tsinghua University Beijing 100084 China Laboratory of Fiber Materials and Modem Textile the Growing Base for State Key Laboratory Qingdao University Qingdao 266071 China Metrohm China Ltd. Beijing Beijing 100005 China

A simple,fast,precise and eco-friendly analytical method for the determination of uric acid（UA） in human urine by ion chromatography（IC） was *** sample pretreatment was not required,only needed centrifugation and *** separation was carried out on a cation exchange column with 2.0 mmol/L nitric acid as mobile phase at the flow-rate 1.0 mL/min.A non-suppressed conductivity detector was *** IC analysis time for one run was within 10 min under the optimized IC *** detection limits were 0.5μg/L（S/N = 3） for uric *** recovery was 100.1%while the relative standard deviation （RSD） was 1.8%from 10 measurements.

关键词： Ion chromatography Uric acid Urine

Multi-walled carbon nanotube as a solid phase extraction adsorbent for analysis of indole-3-butyric acid and 1-naphthylacetic acid in plant samples

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Chinese Chemical Letters 2013年第7期24卷 588-592页

作者： Zong-Hua Wang Jian-Fei Xia Qiang Han Hai-Ning Shi Xin-Mei Guo Hui Wang ming-yu ding Laboratory of Fiber Materials and Modern Textile The Growing Base for State Key LaboratoryCollege of Chemical and Environment EngineeringQingdao University Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology Ministry of EducationDepartment of ChemistryTsinghua University

In this work, a new sample pretreatment method prior to HPLC separations was developed for the determination of auxins in plant samples, Owing to its large surface area and high adsorption capacity, multi-walled carbon nanotube （MWCNT） was chosen as the adsorbent for the extraction of auxins from plant samples. In this study, two important auxins were selected as model analytes, namely indole-3- butyric acid （IBA） and 1-naphthylacetic acid （NAA）. They could be extracted and concentrated due to their π-π stacking interactions with MWCNT. Then HPLC-UV was introduced to detect IBA and NAA after sample pretreatment. Factors that may affect the enrichment efficiency were investigated and optimized. Comparative studies showed that MWCNT was superior to CI 8 for the extraction of the two analytes. Validation experiments showed that the optimized method had good linearity （0.9998 and 0.9960）, high recovery （81.4%-85.4%）, and low detection limits （0.0030 mg/L and 0.0012 mg/L）. The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it was feasible for the determination of auxins in plant samples.

关键词： Multi-walled carbon nanotube Solid phase extraction Indole-3-butyric acid 1-Naphthylacetic acid

Determination of benzoic acid in milk by solid-phase extraction and ion chromatography with conductivity detection

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Chinese Chemical Letters 2013年第3期24卷 243-245页

作者： Zong-Hua Wang Jian-Fei Xia Fu-Yong Zhao Qiang Han Xin-Mei Guo Hui Wang ming-yu ding Laboratory of Fiber Materials and Modern Textile The Growing Base for State Key LaboratoryCollege of Chemical and Environment EngineeringQingdao University Metrohm China Ltd. Beijing Key Laboratory for Microanalytical Methods and Instrumentation Department of ChemistryTsinghua University

A simple, fast, precise and eco-friendly method, based on ion chromatography （IC） with a suppressed conductivity detector, was proposed for the determination of benzoic acid （BA） in milk in this paper. The chromatographic separation was accomplished by using an anion exchange column eluted with 3.2 mmol/L aqueous Na2C03 and 1.0 mmol/L aqueous NaHCO3 at a flow-rate of 0.7 mL/min. The method validation experiment provided excellent results with respect to linearity （correlation coefficient up to 0.9997）, limit of detection （0.1 ug/L）, recovery values （ranging from 88.0% to 93.0%） and relative standard deviation （RSD）（below 2.2%, n = 7）.

关键词： Ion chromatographyBenzoic acidSolid-phase extractionMilk

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隧道磁电阻效应中的两种不同的理论方法

物理学报 2002年第9期51卷 2128-2132页

作者：高鹏郑之明邢定钰南京大学物理系南京210093

使用两种不同的理论方法来计算磁性隧道结中的隧道磁电阻 .结果显示 ,Slonczewski模型得出的隧道磁电阻比Julliere公式得到的要大得多 .在Slonczewski模型中 ,当两边铁磁体的磁化方向相反时 ,为了确保平行于界面方向上的动量守恒 ,费米... 详细信息

使用两种不同的理论方法来计算磁性隧道结中的隧道磁电阻 .结果显示 ,Slonczewski模型得出的隧道磁电阻比Julliere公式得到的要大得多 .在Slonczewski模型中 ,当两边铁磁体的磁化方向相反时 ,为了确保平行于界面方向上的动量守恒 ,费米面上的电子只有一部分参与了隧穿过程 ;而在隧道哈密顿方法中 ,则假设费米面上所有的电子都参与了 .还发现 ,在Slonczewski模型中。

关键词：隧道磁电阻效应 Slonczewski模型隧道哈密顿方法势垒磁致电阻效应隧道结铁磁体

Dynamic Regulation of Hydrogen Bonding Networks and Solvation Structures for Synergistic Solar‑Thermal Desalination of Seawater and Catalytic Degradation of Organic Pollutants

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Nano-Micro Letters 2025年第2期17卷 548-565页

作者： ming‑yuan yu Jing Wu Guang Yin Fan‑Zhen Jiao Zhong‑Zhen yu Jin Qu Beijing Key Laboratory of Advanced Functional Polymer Composites Beijing University of Chemical TechnologyBeijing 100029People’s Republic of China State Key Laboratory of Organic‑Inorganic Composites College of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029People’s Republic of China

Although solar steam generation strategy is efficient in desalinating seawater,it is still challenging to achieve continuous solar-thermal desalination of seawater and catalytic degradation of organic ***,dynamic regulations of hydrogen bonding networks and solvation structures are realized by designing an asymmetric bilayer membrane consisting of a bacterial cellulose/carbon nanotube/Co_(2)(OH)_(2)CO_(3)nanorod top layer and a bacterial cellulose/Co_(2)(OH)_(2)CO_(3)nanorod(BCH)bottom ***,the hydrogen bonding networks inside the membrane can be tuned by the rich surface–OH groups of the bacterial cellulose and Co_(2)(OH)_(2)CO_(3)as well as the ions and radicals in situ generated during the catalysis ***,both SO_(4)^(2−)and HSO_(5)−can regulate the solvation structure of Na^(+)and be adsorbed more preferentially on the evaporation surface than Cl^(−),thus hindering the de-solvation of the solvated Na^(+)and subsequent nucleation/growth of ***,the heat generated by the solar-thermal energy conversion can accelerate the reaction kinetics and enhance the catalytic degradation *** work provides a flow-bed water purification system with an asymmetric solar-thermal and catalytic membrane for synergistic solar thermal desalination of seawater/brine and catalytic degradation of organic pollutants.

关键词： Solar steam generation Seawater desalination Catalytic degradation Bacterial cellulose Cobalt hydroxycarbonate nanorods

Optimization Strategies of Na_(3)V_(2)(PO_(4))_(3) Cathode Materials for Sodium‑Ion Batteries

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Nano-Micro Letters 2025年第2期17卷 204-251页

作者： Jiawen Hu Xinwei Li Qianqian Liang Li Xu Changsheng ding yu Liu Yanfeng Gao School of Materials Science and Engineering Shanghai UniversityShanghai 200444People’s Republic of China Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050People’s Republic of China

Na_(3)V_(2)(PO_(4))_(3)(NVP)has garnered great attentions as a prospective cathode material for sodium-ion batteries(SIBs)by virtue of its decent theoretical capacity,superior ion conductivity and high structural ***,the inherently poor electronic conductivity and sluggish sodium-ion diffusion kinetics of NVP material give rise to inferior rate performance and unsatisfactory energy density,which strictly confine its further application in ***,it is of significance to boost the sodium storage performance of NVP cathode *** to now,many methods have been developed to optimize the electrochemical performance of NVP cathode *** this review,the latest advances in optimization strategies for improving the electrochemical performance of NVP cathode material are well summarized and discussed,including carbon coating or modification,foreign-ion doping or substitution and nanostructure and morphology *** foreign-ion doping or substitution is highlighted,involving Na,V,and PO_(4)^(3−)sites,which include single-site doping,multiple-site doping,single-ion doping,multiple-ion doping and so ***,the challenges and prospects of high-performance NVP cathode material are also put *** is believed that this review can provide a useful reference for designing and developing high-performance NVP cathode material toward the large-scale application in SIBs.

关键词： Sodium-ion batteries Na_(3)V_(2)(PO_(4))_(3) Cathode materials Electrochemical performance Optimization strategies

Surface micro-arrays enhancing electromagnetic interference shielding of polydimethylsiloxane/multiwalled carbon nanotubes nanocomposites

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Nano Research 2025年第1期18卷 508-519页

作者： Ke Jiang Zhi Chen Ji yu Chen Zheng Shan Huang ming Wang Chongqing Key Laboratory of Soft-Matter Material Manufacturing School of Chemistry and Chemical EngineeringSouthwest UniversityChongqing 400715China School of Mechanics Civil Engineering and ArchitecturesNorthwestern Polytechnical UniversityXi’an 710072China Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory(Rongjiang Laboratory) Jieyang 515200China

Herein,the electromagnetic shielding performance of surface concave-convex(SC)and zig-zag micro-arrays was studied by using a simulation prediction and a three-dimensional(3D)printing custom ***,surface stripe concaveconvex(SSC)and surface cylindrical concave-convex(SCC)micro-arrays with or without zig-zag micro-arrays are designed,and their shielding performance is simulated in multi-bands(C-,X-band).The multiwalled carbon nanotubes/polydimethylsiloxane composites(MWCNT/PDMS)with different SC structures and different electrical conductivity are molded in acrylonitrile-butadiene-styrene copolymer(ABS)molds which are printed by a 3D *** results show that the electromagnetic interference shielding effectiveness(EMI SE)of the samples can be enhanced by constructing the SC micro-arrays with zig-zag micro-arrays,and improving with the increase of conductivity and *** addition,the shielding mechanism of the SC-MWCNT/PDMS composites is investigated and discussed by an electromagnetic simulation.

关键词： surface micro-arrays electrical properties electromagnetic interference(EMI)shielding three-dimensional(3D)printing

2D phosphides heterostructures on titanium microfiltration membrane for enhanced ampere-level current density overall seawater splitting

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Nano Research 2025年第1期18卷 249-259页

作者： Wenjing Dai Xin Wang yulong Ma Sisi He ming Chen Zhaohui Yin Shuheng Tian Maolin Wang Shixiang yu Hang Zhang yuanzhe Wang Hong Wang Jianxin Li Faming Gao Bowen Cheng yun Wang Zhen Yin ding Ma Tianjin Key Laboratory of Brine Chemical Engineering and Resource Eco-utilization College of Chemical Engineering and Materials ScienceTianjin University of Science and TechnologyTianjin 300457China State Key Laboratory of Biobased Fiber Manufacturing Technology Tianjin University of Science and TechnologyTianjin 300457China Haian Institute of High-Tech Research Nanjing UniversityHaian 226600China Beijing National Laboratory for Molecular Sciences College of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China State Key Laboratory of Separation Membranes and Membrane Processes Separation Membrane Science and Technology International Joint Research CentreTiangong UniversityTianjin 300387China Centre for Catalysis and Clean Energy School of Environment and ScienceGold Coast CampusGriffith UniversitySouthportQueensland 4222Australia

The advancement of direct seawater electrolysis is a significant step towards sustainable hydrogen production,addressing the critical need for renewable energy sources and efficient resource ***,direct seawater electrolysis has to face several challenges posed by the corrosiveness of highly concentrated chloride and the competitive chlorine evolution reaction(ClER).To overcome these issues,we designed a novel NiP_(2)@CoP electrocatalyst on a porous titanium microfiltration(Ti MF)*** obtained bifunctional NiP_(2)@CoP catalyst outperforms the Pt/C and IrO_(2),as evidenced by its low overpotentials of 192 and 425 mV at a current density of 500 mA·cm^(-2) for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in alkaline seawater(1 M KOH+0.5 M NaCl),***,only 231 and 569 mV overpotentials are required at the current density of 1500 mA·cm^(-2) towards HER and OER in alkaline seawater,*** importantly,no ClER was observed,demonstrating its excellent selectivity to *** selection of porous Ti MF membrane as an electrode substrate further enhances the performance by providing a robust structure that promotes the fast generation and release of gas *** promising outcomes obtained with NiP_(2)@CoP catalysts on Ti MF support,therefore,pave the way for the commercial viability of direct seawater electrolysis technologies at industrial-level current densities.

关键词： direct seawater electrolysis porous titanium microfiltration membrane phosphides heterostructures NiP_(2)@CoP electrocatalyst excellent selectivity to oxygen evolution reaction(OER)