高效液相色谱-串联质谱法同时测定人尿液中7种邻苯二甲酸酯代谢物

建立了同时检测人尿液中7种邻苯二甲酸酯代谢物的高效液相色谱-串联三重四极杆质谱法。尿液经酶水解后,采用萃取柱净化,以2%(v/v)甲酸甲醇溶液为洗脱剂,经苯基柱分离,以0.1%(v/v)乙酸水溶液和0.1%(v/v)乙酸乙腈溶液为流动相进行梯度洗脱,采用电喷雾离子源负离子模式和多反应监测模式采集信号,用同位素内标法进行定量分析。尿液中7种邻苯二甲酸酯代谢物在0.2~200.0 μg/L范围内定量离子的相对峰面积比值与质量浓度均呈良好线性关系(r≥0.99976);检出限(LOD)为13.43~80.21 ng/L,定量限为44.77~267.37 ng/L; 3个水平的加标回收率为88.8%~108.9%,日内和日间精密度均不大于17.05%。该方法可同时准确、灵敏、简便地测定人尿液中7种邻苯二甲酸酯代谢物的暴露水平。     

思想实验及其对化学仿真实验教学的启示

思想实验作为一种研究方法和阐明科学理论的表述方法,广泛应用于各个学科。其基本特征为:思想实验是在头脑中进行的实验,具有非实际的可操作性;思想实验,全凭思维中的抽象形式和抽象运动展开,具有严密的逻辑性;思想实验是人们在长期实验的经验基础上的产物,具有实践性。在化学教学中,随着信息技术的发展,仿真实验逐渐被教学一线所接受。考察仿真实验的相关研究和思想实验的特征可见:仿真实验具有思想实验的特质,仿真实验可视为思想实验在化学实验教学领域的特定表现。有限度地使用仿真实验,有利于促进化学教学手段的现代化和化学实验观念的更新。但仿真实验不能承载所有的实验教学功能,搞好仿真实验教学需以真实场景的实验教学为基础。     

Azomethine-H as a Highly Selective Fluorescent Probe for Fe3+ Detection in 100％ Aqueous Solution and Its Application in Living Cell Imaging

A simple assay for the detection of Fe³⁺ in water by means of fluorescence spectroscopy was developed based on a commercially available reagent, Azomethine-H(A-H), allowing sensing trace levels of Fe³⁺ with high selectivity over other cations. A significant fluorescence quenching of A-H at 424 nm was found after its binding with Fe³⁺ in 100% aqueous solution at pH=7.0, while other physiologically relevant metal ions posed little interference. The fluorescence responses can be well described by the modified Stern-Volmer equation. A good linear relationship(R²=0.9904) was observed up to 1.6×10^-5 mol/L Fe³⁺ ions. The detection limit, calculated via the 3σ IUPAC(international union of pure and applied chemistry) criteria, was 1.95×10^-7 mol/L. Moreover, the colorimetric and fluorescent response of A-H to Fe³⁺ can be conveniently detected by the naked eye, providing a facile method for visual detection of Fe³⁺. The proposed method was used to determine Fe³⁺ in water samples. Moreover, inverted fluorescence microscopy imaging using human umbilical vein endothelial cells shows that A-H can be used as an effective fluorescent probe for detecting Fe³⁺ in living cells.     

液栅型石墨烯场效应管的缓冲液浓度和pH响应特性

本文使用化学气相沉积（Chemical Vapor Deposition,CVD）石墨烯制作了高灵敏度、低噪声的液栅型石墨烯场效应管（Solution-Gated Graphene Field Effect Transistors,SGFETs）,并测试了该器件对磷酸盐缓冲液（Phosphate Buffered Saline,PBS）浓度和pH的响应特性. 随缓冲液浓度的增大,SGFETs转移特性曲线的最小电导点向左偏移,偏移量与溶液浓度的自然对数呈线性关系. 随pH的增大,其最小电导点向右偏移,偏移量与溶液pH呈线性关系. 该响应特性对石墨烯生化传感器排除外界影响因素有一定的指导作用.     

化学课堂中教学自由的不当表现及对策

由于教师对其拥有的教学自由认识不到位,导致教学中存在一些不当表现:利用教材功能的不当;理解教学目标的不当;编辑教辅材料的不当;学习方式引导的不当。为促进教学自由的进一步实现,提出教学建议:教师要勇于担当教学责任、认识教学必然和弘扬教学个性。     

Rapid Absolute Determination Platform of Nucleic Acid for Point-of-care Testing

Nowadays nucleic acid tests are promising to be considered as point-of-care testing(POCT). However, no such devices are currently available that can perform all the functions, including absolute nucleic acid determination, worldwide on-site detection, rapid analysis and real-time results reporting via ubiquitous mobile networks simultaneously with full package and automated means of measurement. In this study, we presented a compact low-cost portable POC automated testing platform with all attributes mentioned above. A disposable self-priming compartmentalization(SPC) microfluidic chip is used to conduct isothermal amplification. The platform also includes a micro-computer controlled heating unit, an inexpensive optical imaging setup, and a mobile device with customized software. It may become a useful tool for the rapid on-site detection of infectious diseases as well as other pathogens.     

水热法生长方式对ZnO纳米棒阵列结构和性能的影响

本文系统地比较了三种方式制备的ZnO纳米棒阵列的结构和性能的异同.根据水热法生长液中碱来源的不同,ZnO纳米棒阵列的生长方式分为三种:N方式(氨水)、H方式(六次甲基四胺)和NH方式(两次N方式和一次H方式).通过扫描电子显微镜,对这三种方式生长的ZnO纳米棒阵列形貌进行了表征.此外,利用X射线衍射仪、透射电子显微镜和激光拉曼光谱对ZnO的结晶性能进行比较.结果表明,ZnO纳米棒阵列的取向性N≈NH>H,ZnO的晶体质量H>NH>N.NH方式综合N方式和H方式的优势,得到了取向性和晶体质量优良的ZnO纳米棒阵列.这将为在进一步应用中有效地选择ZnO纳米棒阵列的制备方式提供重要信息.     

球磨工艺对机械合金化合成Ti2SnC导电陶瓷的影响

采用Ti,Sn和C元素粉末作为反应原料,按Ti2SnC化学计量比作为原料配比(Ti: Sn:C =2: 1:1),通过机械合金化(MA)制备出Ti2SnC导电陶瓷粉体.研究球磨时间、转速、球料比和磨球直径对机械合金化合成Ti2SnC形貌和相变的影响.研究表明:单质混合粉体经过机械合金化(球磨转速550 r/min,球料比10:1,磨球直径12 mm)球磨10 h,生成以Ti2 SnC为主晶相且含有少量Sn和TiC杂质相的混合粉体.较长的球磨时间或较高的转速会抑制Ti2SnC的合成;同样,较大直径的磨球或较高的球料比会使反应体系能量过高,使Ti2SnC分解转化成较稳定的TiC.     

Sn-Al共掺杂ZnO薄膜的制备及其光电性能

采用溶胶凝胶法在普通载玻片上制备了Sn-Al共掺杂ZnO薄膜(ZASO薄膜).利用XRD、扫描电子显微镜、霍尔测试仪、双电测四探针测试仪和紫外-可见分光光度计等设备,研究了Sn-Al掺杂浓度、预烧温度对氧化锌薄膜的晶体结构和光电性能的影响.结果表明:预烧温度为500℃,Sn、Al掺杂浓度分别为1.0at;时,得到的ZASO薄膜的综合光电性能最好,晶粒尺寸较大,方块电阻可达3.3 kΩ/□,光学透过率达92.9;.     

铁酸铋微晶玻璃的析晶行为及介电性能研究

采用整体析晶法制备了铁酸铋微晶玻璃,通过XRD、DSC、FT-IR、Raman、SEM与电性能测试,研究了不同熔融温度对微晶玻璃的物相组成、微观结构及介电性能的影响.研究结果表明,不同熔融温度的微晶玻璃由非晶态的Bi2O3、Fe2O3和晶态的BiFeO3、Bi2Fe4O9组成.在较低的熔融温度时,微晶玻璃中还存在晶态的Bi2O3.在较高的熔融温度时,存在Bi25FeO40相.1070℃熔融的微晶玻璃于600℃晶化12h后,晶粒尺寸均匀,相比于BiFeO3陶瓷具有更高的介电常数(～ 100),更低的介电损耗(～0.14).铁酸铋微晶玻璃特殊的结构降低了漏导电流,测得饱和的电滞回线,饱和极化强度为1.0 μC/cm2.