Diet and lifestyle help mediate colorectal cancer (CRC) risk but the molecular events that mediate these effects are poorly characterized. Several dietary and lifestyle factors can modulate DNA methylation suggesting that they may influence CRC risk through epigenetic regulation of cancer-related genes. The Wnt regulatory genes DKK1 and Wnt5a are important contributors to colonic carcinogenesis and are often silenced by promoter hypermethylation in CRC; however, the dietary contributions to these events have not been explored. To investigate the link between dietary/lifestyle factors and epigenetic regulation of these Wnt signaling genes, we assessed promoter methylation of these genes in a large cohort of Canadian CRC patients from Ontario (n=549) and Newfoundland (n=443) and examined associations to dietary/lifestyle factors implicated in CRC risk and/or DNA methylation including intake of vitamins, fats, cholesterol, fibre, and alcohol as well as BMI and smoking status. Several factors were associated with methylation status including alcohol intake, BMI, and cigarette smoking. Most significantly however, dietary vitamin D intake was strongly negatively associated with DKK1 methylation in Newfoundland (p=0.001) and a similar trend was observed in Ontario. These results suggest that vitamin D and other dietary/lifestyle factors may alter CRC risk by mediating extracellular Wnt inhibition.
A comprehensive three-dimensional numerical model is developed for simulation of the industrial opposed multiburner (OMB) coal−water slurry (CWS) entrained flow gasifier. The CWS gasification process is divided into several submodels, including water evaporation, coal pyrolysis, and homogeneous and heterogeneous char reactions. The "effectiveness factor" method is used to extrapolate the intrinsic char reactivity data to industrial CWS gasifier conditions. Numerical simulations with the proposed models are performed on the industrial OMB gasifier, and the predicted temperature and gas compositions at the outlet of the gasifier are in good agreement with industrial operating data. The profiles of flow field, temperature, and gas composition in the gasifier are described. In addition, the effects of the slurry concentration and oxygen/ coal ratio on the gasifier performance are also studied, which reveal that the lower oxygen/coal ratio or higher slurry concentration leads to higher cold gas efficiency, while the carbon conversion slightly changes about 99%.
A reduced-order model (ROM) is considered a promising solution for engineering simulation of a gasifier. In this study, a ROM of a commercial-scale opposed multiburner gasifier is developed based on a reactor network model (RNM). The RNM blocking for this gasifier is established and validated based on analysis of the gasifier flow field. The particle flow in the gasifier is characterized by the particle residence time in each reactor of the RNM. The random pore model and the "effective factor" method are employed to model the char gasification rate under high pressure and temperature. The interphase heat transfer and heat loss through the refractory wall are calculated. In model validation, the simulation results show well agreement with the industrial data. The model provides distributions of the gas temperature and compositions in the gasifier. Effects of the particle size on the particle temperature and carbon conversion are discussed quantitatively. It is observed that fine particles can be completely converted in the jet zone, while the large ones (>100 μm) are converted mainly in the impinging zone and impinging flow zone.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.