Dynamic Accumulation of β-carotene and Dry Matter in Orange-fleshed Sweetpotato [Ipomoea batatas(L.) Lam] and Their Correlation Analysis

Using three orange-fleshed sweetpotato varieties as experimental materials,16 economic traits at 60 d,75 d,90 d,105 d,120 d and 135 d after planting were measured,so as to revealing the dynamic variations of β-carotene and dry matter accumulation in roots and their relationships with economic traits in orangefleshed sweetpotato.The results showed that the dynamic variations of β-carotene accumulation in tubers varied hugely among different varieties.Interesting,the βcarotene content of all three varieties showed a significant decrease after 120 d,while the dry matter content of them performed a similar ＂fluctuation-type＂.Correlation analysis indicated that β-carotene content of three orange-fleshed sweetpotato varieties had no significant correlation with dry matter content and photosynthetic parameters,but the correlation with other economic traits also varied among varieties.

神经网络算法在X荧光方法中的应用

在X荧光方法中,对物质含量定量分析需要解多元素的复杂能谱,采用神经网络算法解谱具有比较好的效果。介绍了一个三层BP(back propagation)神经网络结构,并推导出LM(Levenberg-Marquardt)算法对网络的权重和偏置的更新。LM算法收敛很快,节约了大量的时间,而且解谱效果良好。还对解谱的残差进行了分析,提出了神经网络解谱的过程中需要注意的问题及其缺陷。在对多元素物质进行含量分析的过程中,采用称量法和解谱法,并对二者的结果进行比较。结果表明,误差很小,而且可以进一步减小误差。

Judgment of Aroma Types of Middle and Upper Flue-cured Tobacco Leaves Based on Stepwise Discriminant Analysis

[Objective] The aim of this study was to establish mathematical models for judging the aroma types of middle and upper flue-cured tobacco leaves according to the contents and proportions of aroma compositions. [Method] The aroma types of tobacco leaves were judged based on stepwise discriminant analysis, using 63 C3F and 65 B2F tobacco leaf samples from 13 tobacco producing regions in 11 provinces of China （Huili in Sichuan, Baokang in Hubei, Wulong in Chongqing, Lu- oyang in Henan, Zhucheng in Shandong, Wuyi Mountain in Fujian, Malong in Yun- nan, Chuxiong in Yunnan, Bijie in Guizhou, Liuyang in Hunan, Suiyang in Guizhou, Kaiyuan in Liaoning, Nanxiong in Guangdong） as calibration samples, and 67 aroma components as indices. And the Fisher discriminant functions were verified using 21 C3F and 19 B2F tobacco leaf samples. [Result] Variation coefficients of the propor- tions were lower than that of contents of most aroma components in middle and upper leaves of the samples, indicating that the proportions were more stable than contents of aroma components. The proportions of benzyl alcohol, solanone, β-dam- ascone, neophytadiene, farnesylacetone A, palmitic acid, thunbergol, methyl linole- nate and cembratriene-diol were all over 1% in both middle and upper leaves, al- though the dominant aroma components of the same aroma type varied between middle and upper leaves. Moreover, 11, 18, 7 and 11 aroma components were re- spectively introduced into the Fisher discriminant functions established based on the contents and proportions of middle and upper flue-cured tobacco leaves, which ex- hibited accuracy rates of 91.7%, 100%, 91.7% and 91.7% in the judgments of other tobacco leaf samples. The results revealed that the components those determined aroma types in middle leaves were obviously more than in upper leaves. In middle leaves, the accuracy rates of aroma type judgment could be improved by using the proportions rather than the contents of aroma components as indices. However, the functions based on the proportions and the contents of aroma components in upper leaves gave close accuracy rates. [Conclusion] The results of the study will provide references for identifying aroma types of flue-cured tobacco leaves in future work.

Hygienic Quality of Fish Depending of Cadmium （Cd） and Lead （Pb） Content in Bottom Sediments of Water Reservoirs Kolinany

Analysis of bottom sediments in water reservoir Kolifiany from the aspect of Cd and Pb contents, the determination of observed heavy metal contents in different parts of carp body （meat muscle, liver and kidney） and the evaluation of hygienic status and suitability of fish meat for the human consumption were performed. For analysis, each tissue sample was dissolved in a solution of nitric acid p.a. （HNO3：HzO = 2：1）; sediment sample in solution of acids （HF-HNO3-HCIO4） and analyzed for presence of Cd, Pb by the atomic absorption spectrophotometer （AAS） Varian Duo 240FS and 240Z. Our results confirmed hygienic harmless of bottom sediments in water reservoir Kolifiany. The Cd, Pb contents in sediments represent no risk within their input into the fish organisms. The Cd content in fish meat is lower than maximum available amount given by legislative norms, and the contents of Pb in fish meat too. The results of Cd, Pb content determination in carp body confirmed that fish muscles belong to suitable foodstuff for the human consumption.