The human dietary selenium requirement in China has been estimated by various methods. The minimum dietary selenium requircment for the prevention of Keshan disease (KD) was found to be around 17 μg/d. On the other h...The human dietary selenium requirement in China has been estimated by various methods. The minimum dietary selenium requircment for the prevention of Keshan disease (KD) was found to be around 17 μg/d. On the other hand, an intake of 40 μg/d is required to maintain the plasma glutathione peroxidase (GPx) activity at plateau. Hence 40 μg/d is considered as the adequate dietary selenium requirement. Studies conducted in a chronic selenosis area indicate thai the toxic dietary selenlum inlake (adverse effect level), which would maintain the characteristic fingernail changes, was approximately 1600 μg/d. The mean value of dietary selenium intakes, which enabled the five patients to recover from fingernail lesions, was found to be 819 ±126μg/d. At a 95% confidence limit, the lower limit is around 600μg/d. Therefore, 600 and 400μg/d were suggested as the individual daily maximum safe selenium intake and the safe dietary selenium intake, respectively,The results were used in the prevention of Se-related endemic KD and Kashin-Beck disease (KBD)展开更多
The spraying of herbicides in crops has become the main form of weed control. Although it means unexpected effects on non-target plants resulted by spraying drift. Thus, improvements in application techniques, as the ...The spraying of herbicides in crops has become the main form of weed control. Although it means unexpected effects on non-target plants resulted by spraying drift. Thus, improvements in application techniques, as the best selection of spray nozzles and adjuvant, are essential to avoid environmental contamination and economic losses. On this work, we evaluate how much adjuvant associated with nozzles can reduce the spray drift. The nozzles used at experiment were air induction flat tip, hollow cone and twinjet and the spray liquids, which were composed of herbicide glyphosate and phosphatidylcholine + propionic acid adjuvant. Measurements were made at wind tunnel and droplet sizer, at laser diffraction method. The models of nozzles influence in droplet size characteristics and in occurrence of spray drift. The use of adjuvants reduces the spray drift only combined with the twinjet nozzle, while for the other models the adjuvant did not reduce the global spray drift at significant levels. The adjuvant reduced the spray drift until 39%, while the nozzles model reduced until 74%. Both techniques when combined were able to reduce until 80%. The model of nozzle has the biggest result on drift mitigation and the use of adjuvants can increase the drift mitigation specially with nozzles that produces smallest droplets.展开更多
文摘The human dietary selenium requirement in China has been estimated by various methods. The minimum dietary selenium requircment for the prevention of Keshan disease (KD) was found to be around 17 μg/d. On the other hand, an intake of 40 μg/d is required to maintain the plasma glutathione peroxidase (GPx) activity at plateau. Hence 40 μg/d is considered as the adequate dietary selenium requirement. Studies conducted in a chronic selenosis area indicate thai the toxic dietary selenlum inlake (adverse effect level), which would maintain the characteristic fingernail changes, was approximately 1600 μg/d. The mean value of dietary selenium intakes, which enabled the five patients to recover from fingernail lesions, was found to be 819 ±126μg/d. At a 95% confidence limit, the lower limit is around 600μg/d. Therefore, 600 and 400μg/d were suggested as the individual daily maximum safe selenium intake and the safe dietary selenium intake, respectively,The results were used in the prevention of Se-related endemic KD and Kashin-Beck disease (KBD)
文摘The spraying of herbicides in crops has become the main form of weed control. Although it means unexpected effects on non-target plants resulted by spraying drift. Thus, improvements in application techniques, as the best selection of spray nozzles and adjuvant, are essential to avoid environmental contamination and economic losses. On this work, we evaluate how much adjuvant associated with nozzles can reduce the spray drift. The nozzles used at experiment were air induction flat tip, hollow cone and twinjet and the spray liquids, which were composed of herbicide glyphosate and phosphatidylcholine + propionic acid adjuvant. Measurements were made at wind tunnel and droplet sizer, at laser diffraction method. The models of nozzles influence in droplet size characteristics and in occurrence of spray drift. The use of adjuvants reduces the spray drift only combined with the twinjet nozzle, while for the other models the adjuvant did not reduce the global spray drift at significant levels. The adjuvant reduced the spray drift until 39%, while the nozzles model reduced until 74%. Both techniques when combined were able to reduce until 80%. The model of nozzle has the biggest result on drift mitigation and the use of adjuvants can increase the drift mitigation specially with nozzles that produces smallest droplets.
