[Application of Fluorescence Spectra and Matrix Analysis in the Classification of Edible Vegetable Oils].

The fluorescence spectra of 42 vegetable oil samples are measured with FS920 fluorescence spectrometer, including 36 pure vegetable oil samples, 3 blend oil samples and 3 mixed oil samples. The fluorescence matrixs (EEMs) are normalized to determine representative excitation wavelength and matrix analysis model of vegetable oils. Vegetable oils are divided into three categories by analyzing representative emission spectra and contour maps in the range of emission wavelength from 260 to 750 nm, and excitation wavelengths from 250 to 550 nm. Applying matrix analysis model to identify pure vegetable oils, blend oils and mixed oils, the correct classification rate is 100% for pure vegetable oils, the composition is close to actual for mixed oils, and the conclusion of soybean and rapeseed oil as base for blend oils is reached. The results demonstrate the capability of the combination of fluorescence spectra technology and matrix analysis model for differentiating and characterizing vegetable oils.

[Molluscicidal effect of plastic film mulch covering method].

OBJECTIVE: To evaluate the molluscicidal effect of the plastic film mulch covering method. METHODS: In the barren land with a lot of Oncomelania hupensis snails, 3 experimental groups were set up, in which respectively using 3 different methods: a simple plastic film mulch covering method, film assisted with ammonium bicarbonate, and film assisted with amine molluscicide. In the canals, two experimental groups were set up, in which respectively using 2 different methods: simple plastic film mulch covering method and film assisted with ammonium bicarbonate. In above-mentioned areas, obstacles were cleared artificially. In each experiment group, 4 observation spots were set up, and 100 living snails were pot in each spot, and then, the plastic film mulch was evenly covered. The status of the snails was observed 3, 7, 15 and 30 days after the intervention. RESULTS: In the barren land, the snail death rates of the simple plastic film group were 20.77% and 96.92% 15 days and 30 days after the intervention, respectively. The snail death rate of the film assisted with amine molluscicide group was 80.46% 3 days after the intervention. In all the experiment groups, the snail death rates were from 96.92 to 100% 30 days after the intervention. CONCLUSION: The plastic film mulch covering method has a great molluscicide effect in the hill subtype and water network type of schistosomiasis epidemic areas.