Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rate...Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rates of lead and zinc and the metallization rate of iron were investigated. The results show that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, and the iron metallization rate was 91.97% under the optimal reduction roasting conditions of a coal dosage of 25.0 wt% and reduction roasting at 1250°C for 60 min. The magnetic concentrate with an iron content of 90.59 wt% and an iron recovery rate of 50.87% was obtained under the optimum conditions in which 96.56% of the reduction product particles were smaller than 37 μm and the magnetic field strength was 24 k A/m. Therefore, the results of this study demonstrate that recovering valuable metals such as lead, zinc, and iron from jarosite residues is feasible using the developed approach.展开更多
Background The therapeutic effect of Bifidobacterium and Lactobacillus on necrotizing enterocolitis(NEC)in very-low-birth-weight preterm infants was controversial,and we aimed to explore the exact impact of the two pr...Background The therapeutic effect of Bifidobacterium and Lactobacillus on necrotizing enterocolitis(NEC)in very-low-birth-weight preterm infants was controversial,and we aimed to explore the exact impact of the two probiotics.Methods The PubMed,EMBASE,Web of Science and Cochrane Library were systematically searched for studies published from January 1,2010 to February 28,2019.Results were combined with fixed-effect model or random-effect model with specific conditions.Sensitivity analysis was conducted by the trim-and-fill method,and the Begger's and Egger's test were used to measure publication bias.Results The meta-analysis included 16 original articles with 4632 very-low-birth-weight preterm infants.With respect to the intervention of Bifidobacterium,we estimated non-significant decrease in the morbidity of NEC with a risk ratio(RR)of 0.75[95%confidence internal(CI)0.56-1.01,P=0.06].Regarding the effect of Lactobacillus,there was no evidence of significant lower risk in the incidence of NEC(RR=0.67,95%CI 0.39-1.17,P=0.16).The use of mixture of probiotics(Bifidobacterium and Lactobacillus)reduced the risk of NEC in the probiotics group(RR=0.45,95%CI 0.25-0.80,P=0.007).Conclusion The mixture of Bifidobacterium and Lactobacillus could prevent the morbidity of NEC in very-low-birth-weight preterm infants.But Bifidobacterium or Lactobacillus alone did not show this effect.展开更多
文摘Lead, zinc, and iron were recovered from jarosite residues using direct reduction followed by magnetic separation. The influence of the coal dosage, reduction temperature, and reduction time on the volatilization rates of lead and zinc and the metallization rate of iron were investigated. The results show that the volatilization rates of lead and zinc were 96.97% and 99.89%, respectively, and the iron metallization rate was 91.97% under the optimal reduction roasting conditions of a coal dosage of 25.0 wt% and reduction roasting at 1250°C for 60 min. The magnetic concentrate with an iron content of 90.59 wt% and an iron recovery rate of 50.87% was obtained under the optimum conditions in which 96.56% of the reduction product particles were smaller than 37 μm and the magnetic field strength was 24 k A/m. Therefore, the results of this study demonstrate that recovering valuable metals such as lead, zinc, and iron from jarosite residues is feasible using the developed approach.
文摘Background The therapeutic effect of Bifidobacterium and Lactobacillus on necrotizing enterocolitis(NEC)in very-low-birth-weight preterm infants was controversial,and we aimed to explore the exact impact of the two probiotics.Methods The PubMed,EMBASE,Web of Science and Cochrane Library were systematically searched for studies published from January 1,2010 to February 28,2019.Results were combined with fixed-effect model or random-effect model with specific conditions.Sensitivity analysis was conducted by the trim-and-fill method,and the Begger's and Egger's test were used to measure publication bias.Results The meta-analysis included 16 original articles with 4632 very-low-birth-weight preterm infants.With respect to the intervention of Bifidobacterium,we estimated non-significant decrease in the morbidity of NEC with a risk ratio(RR)of 0.75[95%confidence internal(CI)0.56-1.01,P=0.06].Regarding the effect of Lactobacillus,there was no evidence of significant lower risk in the incidence of NEC(RR=0.67,95%CI 0.39-1.17,P=0.16).The use of mixture of probiotics(Bifidobacterium and Lactobacillus)reduced the risk of NEC in the probiotics group(RR=0.45,95%CI 0.25-0.80,P=0.007).Conclusion The mixture of Bifidobacterium and Lactobacillus could prevent the morbidity of NEC in very-low-birth-weight preterm infants.But Bifidobacterium or Lactobacillus alone did not show this effect.
