Health risk assessment of arsenic and some heavy metals in the edible crab (Portunus trituberculatus) collected from Hangzhou Bay, China.

In 2018, 108 swimming crabs (P. trituberculatus) were collected from the local market in Zhoushan. Each crab was separated into huang (the edible lipid portion) and meat groups and prepared according to different cooking methods. In most uncooked samples the levels of seven trace metals; mercury, cadmium, lead, zinc, copper, chromium and arsenic were higher in huang than in meat. Cadmium and total arsenic concentrations exceeded the maximum safe residue levels for China. Risk assessments revealed that only the cadmium levels in huang samples posed a toxicological risk to consumers, and uncooked huang were of carcinogenic concern. Cooking methods eliminated the carcinogenic risk and reduced the toxicological risk in huang by approximately 20%. These results show that the seven trace metals identified in P. trituberculatus from Hangzhou bay do not pose a safety concern for consumption of the meat or of the complete crab, after conventional cooking.

Influences of an Aluminum Covering Layer on the Performance of Cross-Like Hall Devices.

This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were characterized using a self-built measurement system. The work analyzes the influences of the aluminum covering on those two aspects of the performance. The aluminum layer covering mainly leads to an eddy-current effect in an unstable magnetic field and an additional depletion region above the active region. Those two points have influences on the sensitivity and the offset voltage, respectively. The analysis guides the designer whether to choose covering with an aluminum layer the active region of the Hall sensor as a method to reduce the flicker noise and to improve the stability of the Hall sensor. Because Hall devices, as a reference element, always suffer from a large dispersion, improving their stability is a crucial issue.

Performance comparison of cross-like Hall plates with different covering layers.

This paper studies the effects of the covering layers on the performance of a cross-like Hall plate. Three different structures of a cross-like Hall plate in various sizes are designed and analyzed. The Hall plate sensitivity and offset are characterized using a self-built measurement system. The effect of the P-type region over the active area on the current-related sensitivity is studied for different Hall plate designs. In addition, the correlation between the P-type covering layer and offset is analyzed. The best structure out of three designs is determined. Besides, a modified eight-resistor circuit model for the Hall plate is presented with improved accuracy by taking the offset into account.