In this research, supercritical carbon dioxide extraction (SFE) showed better extraction effect when compared with Solid- liquid extraction (SLE), Soxhlet extraction (SE) and Ultrasonic extraction (UE), not only in the rate but also the time. The comparison among these three extraction modifiers, including acetone, ethanol and methanol demonstrated that ethanol was preferred to SFE due to its high extraction effect and low toxicology. In addition, parameter of SFE, influence of temperature and pressure were investigated, and the best extraction effect was achieved at the optima conditions, temperature of 40°C and the pressure of 35 MPa. Thus, SFE is a highly effective method for flavonols extraction, requiring minimum energy and producing non-toxic byproduct. SFE-GC system is applied for the evaluation on flavonols that plays a key role in plant resistance to heavy metal, with its content and synthetase gene expression significantly increasing in plant when threatened by heavy metal. Besides, results indicated that flavonols can improve plant resistance to oxidative stress by quenching the redundant ROS in matrix.
In this paper, we propose a semiparametric survival model to investigate the pattern of spatial and temporal variation in
disease prevalence of chronic wasting disease (CWD) in wild deer in Wisconsin over the years 2002 and 2006. The semiparametric
survival model we suggested allows to build a more flexible model than the parametric model with fewer parametric assumptions
by modeling the baseline hazard using a Gamma process prior. Based on the proposed model, we investigate the geographical
distribution of CWD, and assess the effect of sex on disease prevalence. We use a Bayesian hierarchical framework where latent
parameters capture temporal and spatial trends in disease incidence, incorporating sex and spatially correlated random effects.
We also propose bivariate baseline hazard which change over age and time simultaneously to adopt different effects of age
and time on the baseline hazard. Inference is carried out by using MCMC simulation techniques in a fully Bayesian framework.
Our results suggest that disease has been spreaded mainly in the disease eradication zone and male deer show a significantly
higher infection probability than female deer. 相似文献