In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction m...In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction mechanism is summarized.Results indicate that the reaction process of this method can be divided into three stages:stage I is the rapid release of volatiles and the rapid consumption of O_(2),primarily occurring within a reaction time range of 0-0.5 s;stage II is mainly the continuous release and diffusion of volatiles,which is the carbonization and activation coupling reaction stage,and the carbonization process is the main in this stage.This stage mainly occurs at the reaction time range of 0.5 -2.0 s when SL-coal is used as material,and that is 0.5-3.0 s when JJ-coal is used as material;stage III is mainly the activation stage,during which activated components diffuse to both the surface and interior of particles.This stage mainly involves the reaction stage of CO_(2)and H2O(g)activation,and it mainly occurs at the reaction time range of 2.0-4.0 s when SL-coal is used as material,and that is 3.0-4.0 s when JJ-coal is used as material.Besides,the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage.Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure,size of the reactor,and optimal positioning of the activator nozzle in PAC preparation.展开更多
The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storag...The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.展开更多
A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rate...A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.展开更多
目的对质子泵抑制剂和H_2受体阻滞剂预防应激性溃疡的有效性和安全性系统评价进行再评价。方法计算机检索Cochrane图书馆、Pub Med、Embase、Web of Sciene、中国知网(CNKI)、中国科技期刊全文数据库(VIP)、中国生物医学文献数据库(CBM...目的对质子泵抑制剂和H_2受体阻滞剂预防应激性溃疡的有效性和安全性系统评价进行再评价。方法计算机检索Cochrane图书馆、Pub Med、Embase、Web of Sciene、中国知网(CNKI)、中国科技期刊全文数据库(VIP)、中国生物医学文献数据库(CBM)和万方医学数据库,检索时限均从建库至2016年5月。根据纳入排除标准,筛选符合纳入排除标准的系统评价和Meta分析,使用AMSTAR量表评价所纳入系统评价的方法学质量,Grade系统评价结局指标的证据质量,提取原始研究用Rev Man 5.3软件进行Meta分析。结果共纳入7个系统评价/Meta分析,方法学质量评分>7分者仅占41.86%;对21个单个结局指标分别进行质量评价,14个(67.77%)的证据质量均为低或极低。对36个研究(3 820例)数据进行再分析,PPI在预防应激性溃疡出血、临床大出血和显性出血方面优于H_2RA(P<0.001),但是在肺炎发生率、死亡率和ICU住院天数方面,PPI和H_2RA比较差异无统计学意义(P>0.05)。结论 PPI预防ICU的危重患者的应激性溃疡出血优于H_2RA,但原始研究质量不高,仍需后续更多的高质量、结局指标设计全面的前瞻性研究。展开更多
基金supported by the Qingdao Postdoctoral Program Funding(QDBSH20220202045)Shandong provincial Natural Science Foundation(ZR2021ME049,ZR2022ME176)+1 种基金National Natural Science Foundation of China(22078176)Taishan Industrial Experts Program(TSCX202306135).
文摘In this study,the impact of different reaction times on the preparation of powdered activated carbon(PAC)using a one-step rapid activation method under flue gas atmosphere is investigated,and the underlying reaction mechanism is summarized.Results indicate that the reaction process of this method can be divided into three stages:stage I is the rapid release of volatiles and the rapid consumption of O_(2),primarily occurring within a reaction time range of 0-0.5 s;stage II is mainly the continuous release and diffusion of volatiles,which is the carbonization and activation coupling reaction stage,and the carbonization process is the main in this stage.This stage mainly occurs at the reaction time range of 0.5 -2.0 s when SL-coal is used as material,and that is 0.5-3.0 s when JJ-coal is used as material;stage III is mainly the activation stage,during which activated components diffuse to both the surface and interior of particles.This stage mainly involves the reaction stage of CO_(2)and H2O(g)activation,and it mainly occurs at the reaction time range of 2.0-4.0 s when SL-coal is used as material,and that is 3.0-4.0 s when JJ-coal is used as material.Besides,the main function of the first two stages is to provide more diffusion channels and contact surfaces/activation sites for the diffusion and activation of the activated components in the third stage.Mastering the reaction mechanism would serve as a crucial reference and foundation for designing the structure,size of the reactor,and optimal positioning of the activator nozzle in PAC preparation.
基金financial support provided by the National Natural Science Foundation of China (No. 52174106)the Key Technology Research and Development Program (No. 2022YFC2905102)。
文摘The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.
基金Project(51474238)supported by the National Natural Science Foundation of China
文摘A comparative study on the corrosion resistance of 17Ni/（NiFe2O4-10NiO） cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 （volume fraction） are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer （about 50 μm） is thicker than that （about 30 μm） formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe（II） in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.
文摘目的对质子泵抑制剂和H_2受体阻滞剂预防应激性溃疡的有效性和安全性系统评价进行再评价。方法计算机检索Cochrane图书馆、Pub Med、Embase、Web of Sciene、中国知网(CNKI)、中国科技期刊全文数据库(VIP)、中国生物医学文献数据库(CBM)和万方医学数据库,检索时限均从建库至2016年5月。根据纳入排除标准,筛选符合纳入排除标准的系统评价和Meta分析,使用AMSTAR量表评价所纳入系统评价的方法学质量,Grade系统评价结局指标的证据质量,提取原始研究用Rev Man 5.3软件进行Meta分析。结果共纳入7个系统评价/Meta分析,方法学质量评分>7分者仅占41.86%;对21个单个结局指标分别进行质量评价,14个(67.77%)的证据质量均为低或极低。对36个研究(3 820例)数据进行再分析,PPI在预防应激性溃疡出血、临床大出血和显性出血方面优于H_2RA(P<0.001),但是在肺炎发生率、死亡率和ICU住院天数方面,PPI和H_2RA比较差异无统计学意义(P>0.05)。结论 PPI预防ICU的危重患者的应激性溃疡出血优于H_2RA,但原始研究质量不高,仍需后续更多的高质量、结局指标设计全面的前瞻性研究。
