气相色谱-质谱联用法测定金属皂中的多环芳烃

建立了金属皂中16种美国环保局(EPA)优先监控的多环芳烃的气相色谱-质谱(GC/MS)联用测定方法,样品先用二甲基亚砜萃取,再用环己烷进行反萃取,经硅胶柱净化后,用GC/MS分离测定。优化了16种多环芳烃(PAHs)的分离测定条件,结果16种PAHs的平均回收率为75.32%￣98.72%,精密度实验相对标准偏差(RSD)为2.19%￣6.93%,检测限(S/N=5)为0.002￣0.010mg/kg。该方法灵敏度高、准确性好,完全可以满足金属皂中多环芳烃的检测要求。     

The mechanism of the poisoning of ammonia synthesis catalysts by oxygenates O2, CO and H2O: an in situ method for active surface determination

The effect of adding an oxygenated poison (O₂, CO or H₂O) to a hydrogen/nitrogen stream producing ammonia over a triply promoted (K₂O, CaO, Al₂O₃) commercial catalyst is not unsurprisingly rapidly to poison the catalyst. However, immediately the oxygenated poison reacts with the catalyst and before total poisoning has occurred, which in these experiments took 10 min, there was an explosive release of ammonia producing concentrations in the gas phase in excess of the equilibrium value. This is thought to be due to a convulsive reorganisation of the surface of the catalyst in forming regions of an oxide overlayer, resulting in the expulsion of the standing surface nitrogen atom coverage as ammonia. However, in contradistinction to the observation of complete poisoning of the triply promoted catalyst shortly after switching the water (2.9%) into the hydrogen/nitrogen stream, when polycrystalline iron was used as the catalyst, after the initial pulse of ammonia was observed, the small quantity of water (2.9%) in the hydrogen/nitrogen stream resulted in an increased rate ( ×3) of ammonia synthesis which declined only slightly over the twenty minute duration of the experiment. The difference in behaviour between the triply promoted catalyst and the polycrystalline iron is thought to be due to the relative ease of reduction of the latter, so that submonolayer quantities of oxide can be stabilised on the surface of the polycrystalline iron. The promoting effect of this oxide overlayer is either structural or electronic; no distinction can be made from these experiments. The technique of injecting either O₂ or CO into a hydrogen/nitrogen stream which is producing ammonia over promoted catalysts in quantities insufficient to cause complete poisoning and measuring the oxygen coverage of the catalyst to a measured decrease in the ammonia synthesis rate, appears to be a ready, in situ method for the determination of the active catalyst area.     

Product and process parameters determination for quality and cost

The purpose of this study is to conduct a concurrent product and process parameters determination for further cost reduction and quality enhancement. The process design-related parameters, such as process mean, process tolerance and product design-related parameters, such as product tolerance, are considered simultaneously in the proposed approach. To reflect the response from these three key controllable characteristics: process mean, process tolerance and product tolerance, the key measurement score, which is the sum of the mean cost, tolerance cost, quality loss and failure cost, is used to evaluate the present model. Two examples are provided for demonstrating the application of single and multiple quality characteristics.     

气相色谱法测定3-氯-1-丙醇

以填充柱气相色谱对 3 氯 1 丙醇进行了分析研究 ,方法变异系数 0 .5 % ,回收率99.5 0 %～ 10 0 .6 7%     

国内外活性氧化锌的进展

叙述了活性氧化锌的简史，特点、应用、生产方法的进展，活性的测定方法及标准。     

傅立叶变换红外光谱仪测定压缩空气中油的含量

介绍了傅立叶变换红外光谱仪（FTIR）测定压缩空气中油含量的方法，讨论了应用FTIR的注意问题。     

凯氏定氮法在测试氯乙烯-丙烯腈共聚树脂中丙烯腈含量的应用

介绍了凯氏定氮法在测定氯乙烯-丙烯腈共聚树脂中丙烯腈含量的应用及反应原理,对测试结果的准确性和重复性进行了研究,并与灼烧法进行了比较。实验结果表明:采用凯氏定氮法测定氯乙烯-丙烯腈共聚树脂中丙烯腈的含量是可行的,测定结果准确,重现性较好。     

黄姜皂素样品的测定

以浓H2SO4为显色剂,采用分光光度法测定黄姜中的皂素。对皂素提取条件进行了优化,在最佳条件下测定结果令人满意。     

甲氧胺盐酸盐的含量测定方法

提出了以酚酞为指示剂，氢氧化钠为滴定剂测定甲氧胺盐酸盐含量的方法。测定了甲氧胺盐酸盐的离解常数Ka，考察了干扰因素对测定的影响。结果表明，干扰物质NH4Cl在样品中的含量小于5％不影响测定。该方法具有简便、快速，准确等特点,测定了数批样品结果较满意。     

Markov随机场与Gaussian曲线在MR图像分割中的应用

针对扫描的人脑组织MR图像边缘分辨率低、模糊性大的特点,本文提出了一种基于模糊Markov随机场和Gaussian曲线相结合的MR图像最佳阈值分割方法。该方法通过对图像的像素邻域属性的统计将模糊论引入其中,建立模糊Markov随机场,并利用Gaussian曲线对二维直方图最佳一维投影进行拟合,确定出图像中各脑组织的二维阈值点,在二维直方图上实现对脑组织的分割。通过实验表明,本算法能够有效提高脑组织的分辨率,对噪声的鲁棒性、结果区域的连通性相对于一维Otsu和二维Otsu算法都有了很大的提高。