外卖餐具中16种合成酚类抗氧化剂的迁移测定

摘 要：目的 测定外卖餐具中16种合成酚类抗氧化剂(Synthetic phenolic antioxidants, SPAs)的含量,分析外卖餐具中这类污染物的迁移行为。方法 本研究通过液相/气相色谱串联三重四极杆质谱联用技术,测定了6大类不同品牌外卖餐具中16种SPAs的含量,分别以纯净水、4%醋酸(v/v)、10%乙醇水溶液(v/v)、50%乙醇水溶液(v/v)和95%乙醇水溶液(v/v)为食品模拟物,开展不同品牌外卖餐具中主要SPAs的迁移实验。结果 外卖餐具中均可以检出一种以上SPAs,其中丁基化羟基甲苯及其代谢物的含量和检出率最高,2,4-二叔丁基苯酚和新兴化合物2,2''-亚甲基双-(4-甲基-6-叔丁基苯酚)次之,然而2,4-二叔丁基苯酚是外卖餐具最主要的迁移物。 结论 外卖餐具中合成酚类抗氧化剂广泛存在。 2,4-二叔丁基苯酚在外卖餐具中大量迁出,其健康危害需要引起足够关注。     

Phase-field simulation of dendritic sidebranching induced by thermal noise

The influence of undercooling and noise magnitude on dendritic sidebranching during crystal growth was investigated by simulation of a phase-field model which incorporates thermal noise. It is shown that, the sidebranching is not influenced with inclusion of the nonconserved noise, therefore, in order to save the computational costs it is often neglected; while conserved noise drives the morphological instability and is dominant origin of sidebranching. The dependence of temperature field on magnitude of thermal noise is apparent, when Fu gets an appropriate value, noise can induce sidebranching but not influence the dendritic tip operating state. In the small undercooled melt, the thermal diffusion layer collected around the dendrite is thick, which suppresses the growth of its sidebranching and makes the dendrite take on the morphology of no sidebranching, but when the undercooling is great, the thermal diffusion layer is thin, which is advantageous to the growth of the sidebranching and the dendrite presents the morphology of the developed sidebranching.     

压电陶瓷微位移驱动器在精密工件台上的应用研究

以压电陶瓷微位移原理为基础,对精密驱动技术在精密定位工件台上的应用作了实验研究。一个是对工件台的微动台进行驱动,另一个是对导轨直线进行误差补偿。设计了一个包括高压精密可调电源、压电微位移驱动器、作为反馈元件的光栅干涉仪、以及由IBMPC机和几个8031单片机的主从控制系统.     

地震采集仪器倾斜测试（TILT）指标与建模温度关系分析

作为408UL/428XL地震数据采集系统日检测的一个重要组成部分,倾斜度测试是我们检测测线正常与否的系统性指标.文章重点从影响倾斜度测试中建模温度与测试结果的关系出发,提出了一套专门的地震采集仪器倾斜测试指标与检波器及环境的对应关系,并针对野外施工的实际情况提出了一整套关于仪器倾斜测试的现场作业指导方案.     

介孔分子筛Al-MCM-41接枝三丁基氯化锡的表征及催化性能(英文)

Surface organometallic chemistry (SOMC) is a recently developing research field. It is of great significance for the quantitative modification, restoration of solid surface, identification of the physical and chemical nature of surface and the preparation of new catalyst. The production of R 3 Sn-O-MCM-41 (R 3 SnM) was obtained by heating tributyltin chloride and Al-MCM-41 mixture at 170 °C for 5 h under stirring in nitrogen atmosphere. The composition, structure and surface physical and chemical properties of the samples were characterized by inductively coupled plasma mass spectrometry (ICP-MS), 13 C, 119 Sn, 29 Si and 27 Al solid state NMR (nuclear magnetic resonance) spectra, in-situ pyridine infrared spectroscopy (Py-IR), N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), etc. The results of ICP and organic elemental analysis shows that the grafting yield w Sn was 6.46% for R 3 SnM. H 0 (the negative logarithm of the acid concentration)and the number of acid sites for R 3 SnM respectively were 2.77-0.99 and 4.8 mmol·g-1 by the Hammett method. N 2 adsorption-desorption, XRD, TEM analysis showed that R 3 SnM with ordered hexagonal mesopore structure, resulted in the decease of surface areas and pore size as well as the increase of mesoporous volume and surface acidity, as compared to Al-MCM-41. R 3 SnM was used in the synthesis of isoamyl acetate. The yield of isoamyl acetate was 96% when n(isoamyl alcohol)︰n(acetic acid) 1.0︰1.0, 3 R SnM w 5%, 138 °C for 5 h. The catalyst can be reused and the yield of 86% can be attained when catalyst was reused five times at the same catalytic conditions.     

基于模糊故障树分析法实现氢原子钟风险评估

利用模糊故障树分析方法对实际运行的氢原子钟系统进行风险评估。在对氢原子钟系统故障汇总分析的基础上详细论述了氢钟故障树建立的方式，并将引发故障的底事件进行归一化模糊描述。通过对氢原子钟系统发生故障概率以及每个底事件概率重要度的计算及排序，可以对氢原子钟系统发生故障的风险进行评估，找到系统发生故障的薄弱环节，为系统制定提高可靠性的改进措施提供理论依据。     

基于自适应速率模型的低时延视频编码速率控制算法

针对实时视频通信具有的低时延特性,通过研究速率模型形状参数和图像内容之间存在的关系,提出了一种视频图像自适应速率模型,此模型较其它速率模型能够更好地拟合真实码率输出,使得基于该模型速率控制下的输出速率更加平稳。为了避免TMN8模型中使用宏块方差方法得到宏块量化步长所引入的计算量,在帧层一次计算得到视频图像的基本量化步长,并在宏块层对其进行简单调整,从而降低了系统的处理时延。仿真实验表明,此文提出的基于新模型的速率控制算法较TMN8在输出码率稳定性及系统时延上都具有较好的性能。     

微波加热金葡菌对小白鼠致病性和菌液灭活的影响

采用微波加热和电炉加热的方法,对比研究了两种方法加热金黄色葡萄球菌（Staphylococcusaureus）对小白鼠致病性和菌液灭活的影响。研究结果表明：经过微波加热处理的细菌的毒力大大减弱,致病性减弱,对菌液的活性也产生了影响,证明了微波的非热效应在对小白鼠致病性和菌液灭活方面具有非常重要的作用,这进一步验证了微波的杀菌机理,同时也为食品工业消毒杀菌提供了参考。