The bond film on the surface of the CO_(2) sodium silicate used sands is not easy to decompose,therefore,it is difficult to reclaim used sands.A new reclamation method of CO_(2) sodium silicate used sands was develope...The bond film on the surface of the CO_(2) sodium silicate used sands is not easy to decompose,therefore,it is difficult to reclaim used sands.A new reclamation method of CO_(2) sodium silicate used sands was developed by steam leaching,which can reduce the water consumption of reclamation and improve the removal effect of sodium silicate bond film.Firstly,the leaching effect of the sodium silicate sands after 20/200/400/600/800/1,000°C heat preservation treatment was simulated.Furthermore,the influence of the leaching time on the removal effect of the sodium silicate bond film was studied.Finally,the casting properties of the reclaimed sands after the leaching reclamation treatment were tested.The results show for simulated used sands after 30 min of steam leaching,the removal ratio of the alkali exceeds 84.1%,the removal ratio of silicate is 86.2%,and the removal ratio of carbonate is 93.6%.The removal rate of alkali,silicate and carbonate is relatively low in the leaching time of 30-50 min.Considering the reclamation effect and cost,the leaching time is controlled in 30 min.Water consumption is only 60%of the mass of used sands for 30 min steam leaching,while it is 200%for wet reclamation.Morphological analysis shows that most of the hazardous substances in the used sands are removed in 30 min steam leaching,and the reclaimed sands surface after steam leaching in 50 min is as smooth as new sands.After 30 min of steam leaching,the alkali removal effect of the factory used sands can reach 81.5%,the water consumption by the steam leaching reclamation is 58%of the mass of the used sand,which is similar to the result of simulated used sands.The performance of reclaimed sands obtained after 30 min steam leaching is better than that of new sands when the amount of sodium silicate added is 6%of the mass of the reclaimed sands and the CO_(2) blowing time is 15 s:the 24 h ultimate compressive strength of reclaimed sands is 5.6 MPa(equated with new sands),and the collapsibility compressive strength is 5.2 MPa,which is lower than the collapsibility compressive strength of new sands(7.7 MPa).This indicates that the reclamation of CO_(2) sodium silicate used sands by steam leaching is a feasible method.展开更多
Background:Tuberculosis(TB)is the notifiable infectious disease with the second highest incidence in the Qinghai province,a province with poor primary health care infrastructure.Understanding the spatial distribution ...Background:Tuberculosis(TB)is the notifiable infectious disease with the second highest incidence in the Qinghai province,a province with poor primary health care infrastructure.Understanding the spatial distribution of TB and related environmental factors is necessary for developing effective strategies to control and further eliminate TB.Methods:Our TB incidence data and meteorological data were extracted from the China Information System of Disease Control and Prevention and statistical yearbooks,respectively.We calculated the global and local Moran’s I by using spatial autocorrelation analysis to detect the spatial clustering of TB incidence each year.A spatial panel data model was applied to examine the associations of meteorological factors with TB incidence after adjustment of spatial individual effects and spatial autocorrelation.Results:The Local Moran’s I method detected 11 counties with a significantly high-high spatial clustering(average annual incidence:294/100000)and 17 counties with a significantly low-low spatial clustering(average annual incidence:68/100000)of TB annual incidence within the examined five-year period;the global Moran’s I values ranged from 0.40 to 0.58(all P-values<0.05).The TB incidence was positively associated with the temperature,precipitation,and wind speed(all P-values<0.05),which were confirmed by the spatial panel data model.Each 10°C,2 cm,and 1 m/s increase in temperature,precipitation,and wind speed associated with 9%and 3%decrements and a 7%increment in the TB incidence,respectively.Conclusions:High TB incidence areas were mainly concentrated in south-western Qinghai,while low TB incidence areas clustered in eastern and north-western Qinghai.Areas with low temperature and precipitation and with strong wind speeds tended to have higher TB incidences.展开更多
基金This work was financially supported by the State Key Laboratory of New Textile Materials and Advanced Processing Technologies(No.FZ2021014)the Wuhan Science and Technology Bureau Application Foundation Frontier Project(2022023988065216)+2 种基金the National Natural Science Foundation of China(J2124010,51405348,51575405)the Educational Commission of Hubei Province of China(D20171604)the Hubei Provincial Natural Science Foundation of China(2018CFB673).
文摘The bond film on the surface of the CO_(2) sodium silicate used sands is not easy to decompose,therefore,it is difficult to reclaim used sands.A new reclamation method of CO_(2) sodium silicate used sands was developed by steam leaching,which can reduce the water consumption of reclamation and improve the removal effect of sodium silicate bond film.Firstly,the leaching effect of the sodium silicate sands after 20/200/400/600/800/1,000°C heat preservation treatment was simulated.Furthermore,the influence of the leaching time on the removal effect of the sodium silicate bond film was studied.Finally,the casting properties of the reclaimed sands after the leaching reclamation treatment were tested.The results show for simulated used sands after 30 min of steam leaching,the removal ratio of the alkali exceeds 84.1%,the removal ratio of silicate is 86.2%,and the removal ratio of carbonate is 93.6%.The removal rate of alkali,silicate and carbonate is relatively low in the leaching time of 30-50 min.Considering the reclamation effect and cost,the leaching time is controlled in 30 min.Water consumption is only 60%of the mass of used sands for 30 min steam leaching,while it is 200%for wet reclamation.Morphological analysis shows that most of the hazardous substances in the used sands are removed in 30 min steam leaching,and the reclaimed sands surface after steam leaching in 50 min is as smooth as new sands.After 30 min of steam leaching,the alkali removal effect of the factory used sands can reach 81.5%,the water consumption by the steam leaching reclamation is 58%of the mass of the used sand,which is similar to the result of simulated used sands.The performance of reclaimed sands obtained after 30 min steam leaching is better than that of new sands when the amount of sodium silicate added is 6%of the mass of the reclaimed sands and the CO_(2) blowing time is 15 s:the 24 h ultimate compressive strength of reclaimed sands is 5.6 MPa(equated with new sands),and the collapsibility compressive strength is 5.2 MPa,which is lower than the collapsibility compressive strength of new sands(7.7 MPa).This indicates that the reclamation of CO_(2) sodium silicate used sands by steam leaching is a feasible method.
基金This work was supported by the National Basic Scientific Research Program of China （973 Program, No. 2007CB935803）, the National Natural Science Foundation of China （No. 30825018） and the Key Clinical Program of the Ministry of Health of China （No. 2010439）.
基金This study was supported by the Qinghai Center for Disease Control and Prevention(CDC).
文摘Background:Tuberculosis(TB)is the notifiable infectious disease with the second highest incidence in the Qinghai province,a province with poor primary health care infrastructure.Understanding the spatial distribution of TB and related environmental factors is necessary for developing effective strategies to control and further eliminate TB.Methods:Our TB incidence data and meteorological data were extracted from the China Information System of Disease Control and Prevention and statistical yearbooks,respectively.We calculated the global and local Moran’s I by using spatial autocorrelation analysis to detect the spatial clustering of TB incidence each year.A spatial panel data model was applied to examine the associations of meteorological factors with TB incidence after adjustment of spatial individual effects and spatial autocorrelation.Results:The Local Moran’s I method detected 11 counties with a significantly high-high spatial clustering(average annual incidence:294/100000)and 17 counties with a significantly low-low spatial clustering(average annual incidence:68/100000)of TB annual incidence within the examined five-year period;the global Moran’s I values ranged from 0.40 to 0.58(all P-values<0.05).The TB incidence was positively associated with the temperature,precipitation,and wind speed(all P-values<0.05),which were confirmed by the spatial panel data model.Each 10°C,2 cm,and 1 m/s increase in temperature,precipitation,and wind speed associated with 9%and 3%decrements and a 7%increment in the TB incidence,respectively.Conclusions:High TB incidence areas were mainly concentrated in south-western Qinghai,while low TB incidence areas clustered in eastern and north-western Qinghai.Areas with low temperature and precipitation and with strong wind speeds tended to have higher TB incidences.
