The feeding parameters in the final stage of vacuum arc remelting process obviously affect the solute segregation and shrinkage pore depth.Coupled with the electromagnetic field,fluid flow,and solute transport,a numer...The feeding parameters in the final stage of vacuum arc remelting process obviously affect the solute segregation and shrinkage pore depth.Coupled with the electromagnetic field,fluid flow,and solute transport,a numerical model was built to investigate the effect of feeding parameters on the ingot solidification phenomena.The Nb segregation and shrinkage pore depth in the solidified ingot were measured.The results show that the liquid moves along the solidification front and the vertex flow is formed in the liquid pool,which promotes solute transport.In the solidified ingot,the Nb segregation in the lower part is negative,while that in the upper part is positive.With the differential electrode applied,the positive segregation is slightly reduced but the segregation distribution remains unchanged.As the feeding current decreases,the positive segregation zone moves toward the ingot top surface,due to the final solidification position moving upward.With the feeding time extended,the positive segregation moves to the top surface and the shrinkage pore depth is reduced.As the feeding time is set at 12 min,the shrinkage pore depth can be reduced to 21 mm.展开更多
Infant formula milk(IFM)is increasingly utilized as a substitute for natural breastfeeding despite the fact that breast milk has been always recognized as the optimal nourishment method.While IFMs are fortified with e...Infant formula milk(IFM)is increasingly utilized as a substitute for natural breastfeeding despite the fact that breast milk has been always recognized as the optimal nourishment method.While IFMs are fortified with essential nutrients that are crucial for proper growth,they can also harbor non-essential toxic metal contaminants from various sources during the production process.Given the heightened vulnerability of newborns to such contaminants,it is imperative to thoroughly analyze,evaluate,and minimize the toxicity associated with the consumption of such IFMs.However,classical approaches to date,have been always adopted for assessing such risks by finding first the analytical concentration of metals in the IFMs followed by multiplying it by the average daily powder intake(ADI)then dividing by the average infant weight.The outcome is then compared to an established standard such a PTWI to assess the extent of toxicity.The drawback with such studies is the use of a fixed ADI for all samples as if all samples have the same and exact preparation directions while using somewhat different infant masses.Accordingly,this study aims at assessing the toxic risk amongst newborns from IFM consumption through the identification and application of various highly important and toxicity-contributing parameters from each IFM and its directions of preparation label separately which are discussed here for the first time while providing comparisons between the classical approach versus our new approach to highlight its importance.Seventy-three IFMs(0e6 months)were analyzed for lead(Pb),cadmium(Cd),arsenic(As),and aluminum(Al)levels and unlike previous studies,this work incorporated various feeding parameters from each IFM for calculating the intakes thus,revealing potential toxicity risks even in IFMs that are considered safe by the classical approach.Metal contamination was significant,with 97.3%of samples containing detectable Pb,41.1%Cd,16.4%As,and 93.2%Al while highlighting Pb in exceeding its maximum allowable level(MAL).This novel approach,which considers new diverse feeding schedules/parameters that are ironically suggested by manufacturers that have been previously overlooked elsewhere,emphasized IFMs'potential as sources of heightened metal toxicity in comparison to classical approaches.Results highlighted Pb and Al as major concerns,with As and Cd of lesser concern.Findings also emphasized the importance of such new parameters for safeguarding newborn health and should be payed attention to by caregivers.The study strongly and highly recommends adherence to minimum feeding schedules(MFS)and proper scooping techniques to reduce newborn exposure to toxic metals.It also suggests continuous monitoring and stricter regulations by health authorities at the production level of such products so as to provide a safer commodity in the first degree and to also provide better and somewhat uniform and specific feeding labels and precautions on such products.展开更多
基金the support from Science and Technology Program of Hebei(Nos.20311004D and 20591001D)National Natural Science Foundation of China(No.51904024).
文摘The feeding parameters in the final stage of vacuum arc remelting process obviously affect the solute segregation and shrinkage pore depth.Coupled with the electromagnetic field,fluid flow,and solute transport,a numerical model was built to investigate the effect of feeding parameters on the ingot solidification phenomena.The Nb segregation and shrinkage pore depth in the solidified ingot were measured.The results show that the liquid moves along the solidification front and the vertex flow is formed in the liquid pool,which promotes solute transport.In the solidified ingot,the Nb segregation in the lower part is negative,while that in the upper part is positive.With the differential electrode applied,the positive segregation is slightly reduced but the segregation distribution remains unchanged.As the feeding current decreases,the positive segregation zone moves toward the ingot top surface,due to the final solidification position moving upward.With the feeding time extended,the positive segregation moves to the top surface and the shrinkage pore depth is reduced.As the feeding time is set at 12 min,the shrinkage pore depth can be reduced to 21 mm.
基金support from the National Council for Scientific Research in Lebanon(CNRS)and the University of Balamand Internal research grants(CNRS-18-Obeid).
文摘Infant formula milk(IFM)is increasingly utilized as a substitute for natural breastfeeding despite the fact that breast milk has been always recognized as the optimal nourishment method.While IFMs are fortified with essential nutrients that are crucial for proper growth,they can also harbor non-essential toxic metal contaminants from various sources during the production process.Given the heightened vulnerability of newborns to such contaminants,it is imperative to thoroughly analyze,evaluate,and minimize the toxicity associated with the consumption of such IFMs.However,classical approaches to date,have been always adopted for assessing such risks by finding first the analytical concentration of metals in the IFMs followed by multiplying it by the average daily powder intake(ADI)then dividing by the average infant weight.The outcome is then compared to an established standard such a PTWI to assess the extent of toxicity.The drawback with such studies is the use of a fixed ADI for all samples as if all samples have the same and exact preparation directions while using somewhat different infant masses.Accordingly,this study aims at assessing the toxic risk amongst newborns from IFM consumption through the identification and application of various highly important and toxicity-contributing parameters from each IFM and its directions of preparation label separately which are discussed here for the first time while providing comparisons between the classical approach versus our new approach to highlight its importance.Seventy-three IFMs(0e6 months)were analyzed for lead(Pb),cadmium(Cd),arsenic(As),and aluminum(Al)levels and unlike previous studies,this work incorporated various feeding parameters from each IFM for calculating the intakes thus,revealing potential toxicity risks even in IFMs that are considered safe by the classical approach.Metal contamination was significant,with 97.3%of samples containing detectable Pb,41.1%Cd,16.4%As,and 93.2%Al while highlighting Pb in exceeding its maximum allowable level(MAL).This novel approach,which considers new diverse feeding schedules/parameters that are ironically suggested by manufacturers that have been previously overlooked elsewhere,emphasized IFMs'potential as sources of heightened metal toxicity in comparison to classical approaches.Results highlighted Pb and Al as major concerns,with As and Cd of lesser concern.Findings also emphasized the importance of such new parameters for safeguarding newborn health and should be payed attention to by caregivers.The study strongly and highly recommends adherence to minimum feeding schedules(MFS)and proper scooping techniques to reduce newborn exposure to toxic metals.It also suggests continuous monitoring and stricter regulations by health authorities at the production level of such products so as to provide a safer commodity in the first degree and to also provide better and somewhat uniform and specific feeding labels and precautions on such products.
