Three burley tobacco samples from three different areas in China and Brazil were roasted under three processing conditions. The amino acids and basic components of the burley tobacco samples were determined before and after roasting. Routine tobacco variables (reducing sugars, total water-soluble sugars, total nitrogen, total alkaloids, total volatile bases, and pH) were determined according to the Chinese National Standard Methods (CNSM). Free amino acids were determined by high performance liquid chromatography (HPLC). The basic compounds were isolated by use of simultaneous distillation and extraction (SDE) equipment. Their levels were determined qualitatively and quantitatively on a) a gas chromatograph (GC) equipped with a nitrogen-phosphorus detector (NPD) and b) by gas chromatography mass spectrometry (GC-MS). The results indicated that the chemical changes occurring during roasting have a significant impact on burley tobacco quality. Roasting decreased the tobacco pH value and the levels of total nitrogen, reducing sugars, free amino acids, and other nitrogenous substances, such as amines and alkaloids. The latter are usually related to the irritancy and sharp taste of burley tobacco smoke. In contrast, the levels of pyrazines, important contributors to the characteristic burley flavor, increased.
The main purpose of the study is to investigate the mechanical properties around an underground gas storage cavern in bedded salt rock. Firstly, considering the characteristics of the salt rock formation in China, the mechanical model was simplified into a hollow cylinder, which containing non-salt interlayer. In terms of elastic theory, Love displacement function was developed, and the elastic general solution of stress and deformation components were obtained after determining the undetermined coefficients. Under the same condition, numerical simulation was carried out. The validity of the elastic general solution is verified by comparing to numerical simulation results. Furthermore, Based on the feasible general elastic solution, viscoelastic solution was obtained through Laplace transformation and inverse Laplace transform, which could provide reference for the study on the stability and tightness of underground gas storage carven during operation to some extent.