高效液相色谱法测定食品接触材料中丙烯酸酯类单体的迁移量

目的建立食品接触材料中12种丙烯酸酯单体迁移量的高效液相色谱检测方法。方法依据欧盟指令(EU)No.10/2011,采用水性模拟物3%乙酸、10%乙醇、20%乙醇、50%乙醇和油性模拟物异辛烷浸泡食品接触材料,将得到的模拟物通过C18色谱柱(150 mm×4.6 mm,5μm)分离,保留时间定性,峰面积定量。结果 12种单体在0.3~60.0 mg/L(水性模拟物)及0.6~120.0 mg/L(异辛烷模拟物)的浓度范围内呈良好线性,相关系数r2大于0.9993。加标回收率在88.2%~109.3%之间,相对标准偏差为1.19%~7.48%,方法的检出限和定量限分别在0.01~0.12 mg/L和0.03~0.24 mg/L之间。结论该方法前处理简便,分离度好,分析灵敏度高,满足食品接触材料中12种丙烯酸酯单体迁移量的分析要求,并用该方法测定了6批次食品接触材料中丙烯酸酯类单体的迁移水平,甲基丙烯酸甲酯为主要检出。     

1-{N-丙基-N-[2-(2,4-二氯苯氧基)乙基]}氨基甲酰咪唑的合成工艺

探讨了N-丙基-N-[2-(2,4-二氯苯氧基)乙基]氨基甲酰氯合成1-N-丙基-N-[2-(2,4-二氯苯氧基)乙基]氨基甲酰咪唑时溶剂、物料比、碱的种类与用量、反应温度等条件对反应收率的影响。适于工业生产的最佳条件是：氯仿作溶剂、氨甲酰氯咪唑三乙胺=1：1：2、氨甲酰氯的浓度为0．52mol／L、反应温度为氯仿沸点、反应时间为5h。收率85％。     

基于HPL测试的集群系统性能分析与优化

集群系统以很高的性价比和良好的可扩展性而成为当今高性能研究的一大新熟点,如何评价与优化集群系统的特性也成为一个很关键的问题。本文通过采用全世界TOP500计算机排名所用的HPL基准测试,对集群的浮点运算性能进行评测和分析,根据在集群系统上进行的HPL基准测试的结果分析总结了影响其整体性能的重要因素,并对这些方面一一给出具体的分析,提出了针对集群系统具有实际意义和研究价值的优化方向和优化方法。     

Synthesis, characterization, and anomalous dielectric and conductivity performance of one-dimensional (bdaH)InSe2 (bda = 1,4-butanediamine)

A new indium selenide, namely (bdaH)InSe₂ (1) (bda = 1,4-butanediamine) has been solvothermally synthesized and structurally characterized. It belongs to the non-centrosymmetric space group Fdd2. Its structure features an infinite one-dimensional anionic chain of [InSe₂]_nⁿ⁻ with monoprotonated [bdaH]⁺ as charge compensating cation. The organic [bdaH]⁺ cations are joined into a supramolecular one-dimensional chain via N–H···N hydrogen bonding, which further interacts with the inorganic chain via N–H···Se and C–H···Se hydrogen bonding, forming a supramolecular three-dimensional network. Based on such a well-defined structure, the thermal stability, optical, conductivity, and dielectric properties were systematically investigated, showing that dielectric constant, as well as conductivity, had a hump at about 95 °C, which could be attributed to water molecules in the crystal boundary.     

超高效液相色谱-串联质谱法同时检测辣椒中吡唑醚菌酯和戊唑醇农药残留

目的 建立QuEChERS-超高效液相色谱-串联质谱法(ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS)同时检测辣椒中吡唑醚菌酯和戊唑醇农药残留的分析方法。方法 辣椒样品经乙腈提取, N-丙基乙二胺(primary secondary amine, PSA)+石墨化炭黑(graphitized carbon black, GCB)分散吸附剂净化, 采用甲醇(A)和0.1%甲酸水溶液(B)作为流动相进行梯度洗脱, 质谱应用电喷雾正离子源(electrospray ionization, ESI+), 采用多离子监测 (multiple reaction monitoring, MRM)模式对吡唑醚菌酯和戊唑醇的定量离子和定性离子进行监测, 外标法定量。结果 通过优化仪器方法中的流动相体系、质谱调谐参数及前处理过程中的提取溶剂和净化剂, 利用UPLC-MS/MS在6 min内完成吡唑醚菌酯和戊唑醇的分离分析。2种农药在0.001~ 0.100 mg/L范围内呈现出良好的线性关系(r>0.999), 检出限为0.001 mg/kg, 方法定量限为0.0025 mg/kg。当添加水平为0.0025、0.0050、0.0100、0.1000 mg/kg时, 吡唑醚菌酯在辣椒中的平均回收率为72.9%~96.1%, 相对标准偏差为3.5%~8.0% (n=5); 戊唑醇在辣椒中的平均回收率为78.4%~88.5%, 相对标准偏差为2.5%~11.8% (n=5)。 结论 本研究建立的方法检测速度快、灵敏度高、准确度和精密度符合农药残留分析的要求, 适用于辣椒中吡唑醚菌酯和戊唑醇农药残留的同时检测。     

大孔树脂富集分离葡萄叶总黄酮的研究

目的优化大孔吸附树脂分离纯化葡萄叶黄酮类化合物的工艺条件。方法采用分光光度法,以芦丁为标准品,采用硝酸铝显色法测定总黄酮含量;以葡萄叶总黄酮的含量、吸附量和解吸率为考察指标,通过静态及动态实验,筛选出理想的吸附树脂,并通过单因素试验确定了葡萄叶总黄酮富集分离的优选操作条件。结果 D-101树脂是吸附葡萄叶提取液中总黄酮较理想的树脂,对其优化的工艺参数为:最佳吸附p H值:p H=3,洗脱剂浓度:70%的乙醇,最佳上样流速:0.8 m L/min,最佳上样液浓度:65.65 mg/L,最佳解吸流速:0.8m L/min。结论 D-101树脂对葡萄叶总黄酮的吸附量大,解吸容易,环境友好,确定的吸附与洗脱条件简单可行,此工艺具有良好的产业化前景。     

Direct electrochemical reduction of titanium dioxide in Lewis basic AlCl3–1-butyl-3-methylimidizolium ionic liquid

The direct electrochemical reduction of titanium dioxide (TiO₂) to metallic titanium at room temperature is firstly studied in Lewis basic AlCl₃–1-butyl-3-methylimidizolium (AlCl₃–BMIC) ionic liquid. In this study, cyclic voltammetry, potentiodynamic polarization, sampled current voltammetry and X-ray photoelectron spectroscopy (XPS) techniques were utilized. Analysis of the cyclic voltammetry suggested that TiO₂ film can be reduced to metallic Ti. The sampled current voltammetry was applied to elaborate the reduction mechanism and the results showed that this reduction process may include two steps. When the output potential difference of 2.8 V was applied, a TiO₂ cylindrical pellet was partly reduced to metallic Ti. However, due to the very slow reaction rate, there was only about 12 wt% of TiO₂ was reduced during the electrolysis time of 48 h. It was predicted that the process for the direct reduction of solid TiO₂ would be explained as follows: given enough cathode potential, the reduction happened at the cathode/ionic liquids interface, where the oxygen was ionized, then dissolved in the ionic liquid and discharged at the anode, with the metallic Ti left at the cathode.     

不同碳纳米管/羟基磷灰石复合粉末的添加对磷酸钙骨水泥性能和结构的影响

采用物理共混法(PB)、化学共沉积法(CC)和仿生浸泡法(BI)合成了多壁碳纳米管/羟基磷灰石复合粉(MWNTs/HA), 并将其作为磷酸钙骨水泥(CPC)的固相粉末之一, 分别制备了相应的CPC样品。由于MWNTs对液相中水分子的吸附、毛细管作用以及表面存在较多的亲水基团, 使得含有MWNTs的CPC样品的亲水性得以提高, 且初凝时间和终凝时间都有所缩短, 但仍满足临床应用的要求。由于CPC中的MWNTs/HA复合粉末的合成方式不同, 使之对CPC的抗压性能、CPC中HA的结晶性、微观形貌影响均较大, 但并不影响CPC的晶相组成。其中PB法所合成的MWNTs/HA复合粉末能促进CPC中纳米级HA晶体的转化和生长, 使针状HA含量的表现为最高, 且抗压力学性能为最好, 其抗压强度和弹性模量分别较空白CPC提高了48.23%和41.87%。     

宽带隙、高折射率聚偏四氟乙烯/TiO2-ZrO2光学膜的制备和表征

以氧氯化锆(ZrOCl₂·8H₂O)为锆源, 钛酸丁酯(Ti(OBu)₄)为钛源, 聚偏氟乙烯(PVDF)为有机添加剂, 采用溶胶–凝胶法在K9玻璃基片上制备PVDF/TiO₂-ZrO₂光学膜, 提高了ZrO₂-TiO₂光学膜的综合性能。然后采用SEM、FT-IR、接触角以及紫外/可见/近红外透射光谱等手段对PVDF/TiO₂-ZrO₂光学膜的组成、光学性能和抗激光损伤阈值进行了研究。SEM测试表明, 在K9玻璃基片上制备了光学膜。PVDF的添加导致水与薄膜的接触角增大。ZrO₂-TiO₂光学膜的光学带隙随ZrO₂含量的增加而略微增大, PVDF/ZrO₂(50mol%)-TiO₂薄膜的光学带隙随PVDF质量分数的增加而增大。另外, ZrO₂-TiO₂光学膜的折射率随ZrO₂摩尔分数的减小而增大, PVDF/ZrO₂(50mol%)-TiO2膜的折射率随PVDF质量分数的增加而增大。