Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study ...Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study is to provide a reference for the accurate estimation of the total LNO_(x) in the mainland of China based on cloud-to-ground lightning(CG)location data from 2014 to 2018.The energy of each CG flash was based on the number of return strokes per CG flash,the peak current of each return stroke,and the assumed CG breakdown voltage.The energy of intracloud lightning(IC)was based on the estimated frequencies of IC and the assumed energy of each IC flash.Combining the energy of lightning and the number of nitric oxide(NO)molecules produced by unit energy(ρno),the total LNO_(x) production in the mainland of China was determined.The LNO_(x) in the mainland of China estimated in this study is in the range(0.157-0.321)×10^(9) kg per year[Tg(N)yr-1],which is on the high end of other scholars’works.Negative cloud-to-ground lightning(NCG)flashes produce the most moles of NO_(x),while positive cloud-to-ground lightning(PCG)flashes produce the least total moles of NO_(x).The breakdown voltage of PCG is greater than that of IC or NCG,while the latter has a greater output of LNO_(x).展开更多
To reduce CO_(2) emissions from coal-fired power plants,the development of low-carbon or carbon-free fuel combustion technologies has become urgent.As a new zero-carbon fuel,ammonia(NH_(3))can be used to address the s...To reduce CO_(2) emissions from coal-fired power plants,the development of low-carbon or carbon-free fuel combustion technologies has become urgent.As a new zero-carbon fuel,ammonia(NH_(3))can be used to address the storage and transportation issues of hydrogen energy.Since it is not feasible to completely replace coal with ammonia in the short term,the development of ammonia-coal co-combustion technology at the current stage is a fast and feasible approach to reduce CO_(2) emissions from coal-fired power plants.This study focuses on modifying the boiler and installing two layers of eight pure-ammonia burners in a 300-MW coal-fired power plant to achieve ammonia-coal co-combustion at proportions ranging from 20%to 10%(by heat ratio)at loads of 180-to 300-MW,respectively.The results show that,during ammonia-coal co-combustion in a 300-MW coal-fired power plant,there was a more significant change in NO_(x) emissions at the furnace outlet compared with that under pure-coal combustion as the boiler oxygen levels varied.Moreover,ammonia burners located in the middle part of the main combustion zone exhibited a better high-temperature reduction performance than those located in the upper part of the main combustion zone.Under all ammonia co-combustion conditions,the NH_(3) concentration at the furnace outlet remained below 1 parts per million(ppm).Compared with that under pure-coal conditions,the thermal efficiency of the boiler slightly decreased(by 0.12%-0.38%)under different loads when ammonia co-combustion reached 15 t·h^(-1).Ammonia co-combustion in coal-fired power plants is a potentially feasible technology route for carbon reduction.展开更多
Various Mn-based catalysts for NO oxidation were prepared using MnO_(x)as active compound,while Ti O_(2)and Al_(2)O_(3)were adopted as catalyst support.The performance of the catalysts was tested to study the effect o...Various Mn-based catalysts for NO oxidation were prepared using MnO_(x)as active compound,while Ti O_(2)and Al_(2)O_(3)were adopted as catalyst support.The performance of the catalysts was tested to study the effect of support on Mn-based catalyst activity.Performance of the catalysts followed as Mn_(0.4)/Al>Mn_(0.2)/Al>Mn_(0.4)/Ti>Mn_(0.2)/Ti>MnO_(x)>Al_(2)O_(3)on the whole,indicating the synergism of MnO_(x)and Al_(2)O_(3)for NO catalytic oxidation.Results were analyzed according to characterization data.Adsorbed oxygen on catalyst rather than lattice oxygen was detected as the active oxidizer for NO oxidation.As catalyst support,Al_(2)O_(3)provided more sites to carry surface adsorbed oxygen than TiO_(2),resulting in the presence of more active oxygen on Mn O_(x)/Al_(2)O_(3)than on MnO_(x)/TiO_(2).Moreover,MnO_(x)/Al_(2)O_(3)possessed high surface area and pore volume,which greatly benefited the adsorption of NO on catalyst and further favored the oxidation of NO by active oxygen.All these advantages helped Mn_(0.4)/Al exhibited the best catalytic efficiency.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 91537209 and 91644224)
文摘Lightning-generated nitrogen oxides(LNO_(x))have a major influence on the atmosphere and global climate change.Therefore,it is of great importance to obtain a more accurate estimation of LNO_(x).The aim of this study is to provide a reference for the accurate estimation of the total LNO_(x) in the mainland of China based on cloud-to-ground lightning(CG)location data from 2014 to 2018.The energy of each CG flash was based on the number of return strokes per CG flash,the peak current of each return stroke,and the assumed CG breakdown voltage.The energy of intracloud lightning(IC)was based on the estimated frequencies of IC and the assumed energy of each IC flash.Combining the energy of lightning and the number of nitric oxide(NO)molecules produced by unit energy(ρno),the total LNO_(x) production in the mainland of China was determined.The LNO_(x) in the mainland of China estimated in this study is in the range(0.157-0.321)×10^(9) kg per year[Tg(N)yr-1],which is on the high end of other scholars’works.Negative cloud-to-ground lightning(NCG)flashes produce the most moles of NO_(x),while positive cloud-to-ground lightning(PCG)flashes produce the least total moles of NO_(x).The breakdown voltage of PCG is greater than that of IC or NCG,while the latter has a greater output of LNO_(x).
文摘目的探讨新生儿持续肺动脉高压(persistent pulmonary hypertension of newborn,PPHN)患儿血清人CXC型趋化因子配体8(C-X-C motif chemokine ligand 8,CXCL8)、CXCL12与一氧化氮吸入治疗临床转归的关系。方法选择2021-08/2023-05月作者医院收治并给予一氧化氮吸入治疗的PPHN患儿135例为研究对象。根据患儿出院时临床转归结局分为死亡组(n=32)和存活组(n=103)。比较两组PPHN患儿血清CXCL8、CXCL12水平。单因素及多因素Logistic回归模型分析接受一氧化氮吸入治疗PPHN患儿临床转归的影响因素。受试者工作特征(receiver operating characteristic,ROC)曲线分析血清CXCL8、CXCL12对接受一氧化氮吸入治疗PPHN患儿临床转归的预测价值。结果死亡组患儿血清CXCL8、CXCL12水平显著高于存活组(P均<0.05)。多因素Logsitic回归分析结果显示,血清CXCL8水平升高、血清CXCL12水平升高、早产、出生时Apgar评分0~3分、合并并发症是接受一氧化氮吸入治疗的PPHN患儿死亡的危险因素,肺表面活性物质应用、吸入一氧化氮早期反应则是保护因素(P<0.05)。ROC曲线分析结果显示,血清CXCL8、CXCL12联合检测对接受一氧化氮吸入治疗的PPHN患儿死亡预测的曲线下面积(area under the curve,AUC)为0.828,大于血清CXCL8、CXCL12单独检测(AUC分别为0.762、0.714)。结论PPHN患儿血清CXCL8、CXCL12水平升高与接受一氧化氮治疗的不良临床转归有关,且CXCL8、CXCL12水平升高是PPHN患儿死亡的危险因素。CXCL8、CXCL12联合检测对接受一氧化氮治疗PPHN患儿死亡具有较高的预测价值。
基金supported by the National Key Research and Development Program of China(2023YFB4005700,2023YFB4005705,and 2023YFB4005702-03)the Academy-Local Cooperation Project of the Chinese Academy of Engineering(2023-DFZD-01)+4 种基金the National Natural Science Foundation of China(52207151)the Natural Science Foundation of Anhui Province(2208085QA29)the University Synergy Innovation Program of Anhui Province(GXXT-2022025)the independent project of the Energy Research Institute of Hefei Comprehensive National Science Center(Anhui Energy Laboratory22KZZ525,23KZS402,22KZS301,and 22KZS304).
文摘To reduce CO_(2) emissions from coal-fired power plants,the development of low-carbon or carbon-free fuel combustion technologies has become urgent.As a new zero-carbon fuel,ammonia(NH_(3))can be used to address the storage and transportation issues of hydrogen energy.Since it is not feasible to completely replace coal with ammonia in the short term,the development of ammonia-coal co-combustion technology at the current stage is a fast and feasible approach to reduce CO_(2) emissions from coal-fired power plants.This study focuses on modifying the boiler and installing two layers of eight pure-ammonia burners in a 300-MW coal-fired power plant to achieve ammonia-coal co-combustion at proportions ranging from 20%to 10%(by heat ratio)at loads of 180-to 300-MW,respectively.The results show that,during ammonia-coal co-combustion in a 300-MW coal-fired power plant,there was a more significant change in NO_(x) emissions at the furnace outlet compared with that under pure-coal combustion as the boiler oxygen levels varied.Moreover,ammonia burners located in the middle part of the main combustion zone exhibited a better high-temperature reduction performance than those located in the upper part of the main combustion zone.Under all ammonia co-combustion conditions,the NH_(3) concentration at the furnace outlet remained below 1 parts per million(ppm).Compared with that under pure-coal conditions,the thermal efficiency of the boiler slightly decreased(by 0.12%-0.38%)under different loads when ammonia co-combustion reached 15 t·h^(-1).Ammonia co-combustion in coal-fired power plants is a potentially feasible technology route for carbon reduction.
基金supported by the National Natural Science Foundation of China(51906193)the Fundamental Research Funds for the Central Universities(xjh012019013)+1 种基金the Basic Research Program of Natural Science in Shaanxi Province(2020JQ-039)support from Young Talent Support Program of Xi'an Association for Science and Technology。
文摘Various Mn-based catalysts for NO oxidation were prepared using MnO_(x)as active compound,while Ti O_(2)and Al_(2)O_(3)were adopted as catalyst support.The performance of the catalysts was tested to study the effect of support on Mn-based catalyst activity.Performance of the catalysts followed as Mn_(0.4)/Al>Mn_(0.2)/Al>Mn_(0.4)/Ti>Mn_(0.2)/Ti>MnO_(x)>Al_(2)O_(3)on the whole,indicating the synergism of MnO_(x)and Al_(2)O_(3)for NO catalytic oxidation.Results were analyzed according to characterization data.Adsorbed oxygen on catalyst rather than lattice oxygen was detected as the active oxidizer for NO oxidation.As catalyst support,Al_(2)O_(3)provided more sites to carry surface adsorbed oxygen than TiO_(2),resulting in the presence of more active oxygen on Mn O_(x)/Al_(2)O_(3)than on MnO_(x)/TiO_(2).Moreover,MnO_(x)/Al_(2)O_(3)possessed high surface area and pore volume,which greatly benefited the adsorption of NO on catalyst and further favored the oxidation of NO by active oxygen.All these advantages helped Mn_(0.4)/Al exhibited the best catalytic efficiency.
基金supported by the National Natural Science Foundation of China(51568068)the Young and Middle-aged Academic and Technical Leaders Reserve Talent Project(202105AC160054).
