Stability of the 13C column separation in industrial mode of operation
Based on the original cryogenic column conceived and built by National Institute for Research and Development of Isotopic and Molecular Technologies Cluj-Napoca, it is necessary to implement control algorithms for the industrial mode of operation of this equipment, in order to produce some chemical compounds with higher concentration in (13C), compounds asked in various domains. The present work deals with column efficiency analysis and stability in industrial mode of operation.
Electrical power monitoring and control in 13C isotope separation column boiler
One of the main elements of a cryogenic (13C) separation column is the boiler. The control of the power supply which feeds the boiler's resistance is of major importance. In order to ensure a safe and stable operation of the plant, a monitoring and control unit is designed using NI PXI-8183 process computer. The developed LabVIEW™ application implements a PI controller and also data logging. Step response and disturbance rejection test are carried out to prove the feasibility of the design.
Human exposure to methylmercury from crayfish (Procambarus clarkii) in China
Methylmercury (MeHg) accumulation in aquatic food raises global concerns about human exposure to MeHg. Crayfish is the world’s third largest farmed crustacean species and a favorite aquatic food in many countries. However, human health hazard due to MeHg exposure via crayfish consumption is unclear, partly because appropriate survey data are lacking. We report on mercury concentrations and speciation in edible tail muscle of crayfish collected from restaurants in 23 Chinese cities. On average, MeHg constituted 99.1 % of mercury in tail muscle, and MeHg concentrations were comparable with those reported for fish in China. Variation in MeHg concentrations was not attributable to broad geographic region (i.e., provinces) or tail length. For different populations, potential health risk (characterized by hazard quotient or HQ) of MeHg exposure through crayfish consumption depended largely on crayfish consumption rates. In particular, a health hazard (HQ > 1) was found for high-rate consumers (i.e., 95 %ile or higher) in some cities in the middle and lower reaches of the Yangtze River (MLYR), during the peak consumption season. Our results suggest that more attention should be paid to dietary MeHg intake via crayfish consumption in China, particularly for communities with high consumption in MLYR.