[Analysis of urine cadmium and blood cadmium of workers before and after the cadmium dust control].

OBJECTIVE: To analyze the urinary cadmium, blood cadmium and urinary beta2-MG of workers in a zinc powder processing plant before and after the cadmium dust control, and to explore the effects of dust control on the prevention and treatment of cadmium hazards. METHODS: The on-site occupational hazard survey was used to investigate the changes of urine cadmium, blood cadmium and beta3-MG of 84 workers exposed to cadmium before and after the treatment by self-control analysis for evaluating the effects of dust control measures in a zinc powder processing plant. RESULTS: After treatment of the cadmium dust, the geometric mean of zinc dust in the workplace significantly decreased from 3.38 mg/m3 to 2.22 mg/m3 (P < 0.01). The geometric mean concentration of blood cadmium [(2.19 +/- 1.19) microg/L] and urine cadmium [(1.96 +/- 0.74) microg/g Cr] before treatment were significantly higher than those of one year [(1.63 +/- 0.83) microg/L] and [(1.25 +/- 0.83) microg/g Cr] and two years [(1.36 +/- 0.95) microg/L] and [(0.94 +/- 0.72) microg/g Cr] after the cadmium dust control (P < 0.01), respectively. The positive correlations analysis between urine cadmium and blood cadmium concentration of one and two years before and after the cadmium dust treatment implied that there was significant difference (r = 0.466, P < 0.01). CONCLUSION: Dust treatment could reduce the impact of low concentration cadmium on the urine cadmium and blood cadmium concentrations of the workers exposed to cadmium, and effectively prevent the cadmium poisoning.

Modifying spin current filtering and magnetoresistance in a molecular spintronic device.

The zigzag edged graphene nanoribbon (ZGNR) is excellent for spintronics devices, and many efforts have been made to investigate its properties such as spin filtering, rectification and magnetoresistance. Here we propose a molecular spintronic transport device based on two ZGNR electrodes connected with a dibenzo[a,c]dibenzo[5,6:7,8]quinoxalino[2,3-i]phenazine (DDQP) molecule. By performing first-principles electron transport computations, we found an enhanced spin polarized current-voltage curve, giant spin filter efficiency, magnetoresistance and rectification ratio properties of the device compared to its all-carbon molecular analogue. Our systematic investigation suggests the vital role played in spin polarized electron transport by nitrogen atoms in DDQP, the ZGNR probe's width and terminal geometry, especially the increased spin filter efficiency with higher ZGNR width.