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Objective:To develope and analyze and optimize the performance of some kinds of environmentally friendly flexible X-ray protective materials in attempt to tackle the various environmental and high energy consumption problems in the development of traditional medical X-ray protective clothing.Methods:The Monte Carlo program was used to establish a simplified model of medical X-ray tube. The aim was to carry out numerical simulation and prediction of the shielding materials′ performance against X-ray, prepare the flexible X-ray shielding materials through experiments and test and verify the their shielding performances The development and optimization path was also obtained by comparing the result between simulation and experiment.Results:Bi was the preferred alternative to toxic Pb elements, while W was able to compensate for weak X-ray absorption zone of Bi. The shielding efficiency of the composite material doped with 25% Bi+ 25% W was able to reach 77.8% and 66.3% at 80 and 120 kV p tube voltages, respectively. Conclusions:With both the selection of elements and the optimization of functional particles, the combination of W and Bi is an economical, environmentally friendly, and efficient shielding way within the energy range of medical diagnostic X-rays. The numerical simulation helps reduce experimental costs, shorten the research period, and improve the design efficiency of X-ray shielding materials.
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Objective To investigate the contamination and dietary intake of the aluminium in commercial foods in Shaanxi Province,and evaluate its potential health risks in Shaanxi population.Methods Six hundred and sixty-six samples from 8 kinds of foods in Shaanxi Province were collected from 2013 to 2015.The aluminium contents were detected according to National Food Contamination and Harmful Factors in Risk Monitoring Manual,and dietary intake of aluminium in Shaanxi population was evaluated by point assessment model with of nutritional survey date.Results The average dietary intake of aluminium was 0.154 9 mg/kg BW per day,and the dietary intake of woman aged 18 to 59 years old was the highest,with an average of 0.178 5 mg/kg BW per day.When aluminum intake of the 97.5 percentile,the dietary intake of aluminium in children aged 2 to 7 years old was the highest.The margins of safety (MOS) of all age groups were smaller than 1,while the MOS of high exposure (P97.5) group was above 1.Fried and baked food were the main sources of aluminium exposure in two age groups (2-7 years and 8-12 years old group),while fried food,cold noodle and starch products were the main sources of aluminium exposure for others.Conclusion Dietary intake (tP97.5) of aluminium exceeded the provisional tolerable weekly intake (PTWI).The dietary intake of aluminium in women and children was high.Fried food was the main sources of aluminium exposure in all age groups.