The aim of this work is to establish objective methods to quantitatively analyze e-cigarettes’ sweetness. Sixty samples of e-liquid were collected and measured by electronic tongue. Based on correlation analysis of electronic tongue data and artificial sensory data, three sweetness evaluation models were established by partial least squares, artificial neural network and support vector machine. Comparison results indicated that the support vector machine model was the most reliable for predicting sweetness of unknown e-cigarette samples. The correlation coefficient of the model was 0.96 with average relative error of predicted results of 7.30% and root mean square error of predicted results of 0.61. It was concluded that the evaluation model based on the combination of electronic tongue and the support vector machine can achieve reliable prediction of unknown e-cigarettes’ sweetness.
Field experiment was set up to select tobacco samples with different alkaloid composition by choosing different nicotine conversion strains of TN86 under the same field management and air-curing conditions. The selected samples were stored in temperature/humidity-controlled chamber at 45 °C for 12 d to explore the source of TSNAs accumulation during high temperature storage and its relationship with alkaloid content. Results showed that significant variation of individual alkaloids existed among 90 tobacco plants with greatest differences being observed for nicotine and nornicotine contents. With approximately same levels of total alkaloids, NO3-N and NO2-N contents, TSNAs contents at 45 °C for 12 d were significantly higher than those before storage. The increase of NNN and NNK contents during storage was significantly positively correlated with their precursors, nicotine and nornicotine, respectively. With the increase of nornicotine content, the net increase of NNN from nornicotine nitrosation during stora
【Objectives】This paper aimed to study effects of biochar on soil biological characteristics and soil respiration rate of Cd contaminated soil.【Methods】Experiment was carried out in 2016 by means of pot plants (25kg soil per pot). The added exogenous Cd concentrations were 0mg/kg (G0), 30mg/kg (G1), 60 mg/kg (G2) and the biochar concentrations were 0g/kg (T0), 10g/kg (T1), 20g/kg (T2) respectively. A total of nine treatments were used for the two-factor test, which were G0T0, G0T1, G0T2, G1T0, G1T1, G1T2, G2T0, G2T1, G2T2. Soil microorganisms and soil microbial biomass (carbon, nitrogen), soil enzyme activity and soil respiration rate were measured in different periods. Results showed that soil urease activity, number of soil bacteria and actinomycetes and soil microbial biomass carbon and microbial biomass nitrogen and soil respiration rate increased significantly along with the application of biochar, and all reached higher level 55d after transplanting. Soil respiration rate increased with growth period, an