This work creates a droplet battery model based on the electrolyte performance in the porous electrode, studies the current density on the mesoscopic scale, and explains how the mesoscopic structure of the porous elec...This work creates a droplet battery model based on the electrolyte performance in the porous electrode, studies the current density on the mesoscopic scale, and explains how the mesoscopic structure of the porous electrode influences the current density on the air-diffusion electrode. Near the three-phase line, there is a strong band containing nearly 80% current. For porous electrodes, the total current is proportional to the length of the strong band. Thus, it can be inferred that on the macroscopic scale, the longer the total length of the strong band on unit area is, the larger the current density is.展开更多
A cement factory nearby communities raise pollution concerns. This study assessed air pollution levels for respirable particulate matter (PM2.5 and PM10) and heavy metals (lead, chromium, nickel, cadmium, zinc and cop...A cement factory nearby communities raise pollution concerns. This study assessed air pollution levels for respirable particulate matter (PM2.5 and PM10) and heavy metals (lead, chromium, nickel, cadmium, zinc and copper) adjacent to a cement factory in Ewekoro and neighbouring communities (Papalantoro, Lapeleko and Itori) in Ogun State, Nigeria. Respirable particulate matter (PM2.5 and PM10) and heavy metals were measured using an ARA N-FRM cassette sampler. Each location sampled was monitored for eight continuous hours daily for 12 days. The PM2.5, PM10 and heavy metals results were compared with different standards, including those of the World Health Organization (WHO), Nigeria’s National Environmental Standard and Regulation Enforcement Agency (NESREA) and Canadian Ambient Air Quality Standards (CAAQS). The PM levels fell within 11 - 19 μg/m3 of the air management level of CAAQS, which signifies continuous actions are needed to improve air quality in the areas monitored but below the NESREA standard. The mean Cd, Cr and Ni concentrations in the cement factory area and the impacted neighbourhoods are higher than the WHO/EU permissible limits, while Zn and Cu were below the WHO/EU permissible limit. A risk assessment hazard quotient (HQ) for Cr was above the WHO/EU safe level (=1) in adults and children throµgh ingestion, inhalation and dermal contact at all the monitoring sites. The HQ for Ni and Cd was higher than the safe level in the cement factory area and Papalantoro, while Zn was at safe levels.展开更多
Rechargeable alkali metal-air batteries are considered as the most promising candidate for the power source of electric vehicles(EVs) due to their high energy density. However, the practical application of metal-air b...Rechargeable alkali metal-air batteries are considered as the most promising candidate for the power source of electric vehicles(EVs) due to their high energy density. However, the practical application of metal-air batteries is still challenging. In the past decade, many strategies have been purposed and explored, which promoted the development of metal-air batteries. The reaction mechanisms have been gradually clarified and catalysts have been rationally designed for air cathodes. In this review, we summarize the recent development of alkali metal-air batteries from four parts: metal anodes, electrolytes, air cathodes and reactant gases, wherein we highlight the important achievement in this filed. Finally problems and prospective are discussed towards the future development of alkali metal-air batteries.展开更多
Air pollution present the greatest threat to human health and welfare in urban environments. Population growth, industrial activities, expanded transport system, vehicular traffic, poor road planning, poor land use an...Air pollution present the greatest threat to human health and welfare in urban environments. Population growth, industrial activities, expanded transport system, vehicular traffic, poor road planning, poor land use and traffic congestion contribute to the problem. Particulate matter (PM<sub>2.5</sub> and PM<sub>10</sub>) has become the principal pollutants due to increased material use, energy demand and use as a result of global economic growth. This study assessed the levels of PM<sub>10</sub> in ambient air and heavy metal composition in Nairobi city. Sampling sites were classified into three categories namely;controlled areas, industrial and residential areas as proscribed in the EMCA Air Quality Regulations, 2014. Portable Mini-Vol ambient air samplers were used for fine particulate monitoring. The concentrations of manganese, lead, and cadmium was determined in PM<sub>10</sub> samples from all sampling sites. The lead concentration mean was 0.07 ± 0.06 μg/m<sup>3</sup>, 0.34 ± 0.35 μg/m<sup>3</sup> and 1.10 ± 0.59 μg/m<sup>3</sup> for residential, controlled and industrial areas respectively. Generally, all afternoons had high particulate matter while the lowest concentration levels of PM<sub>10</sub> were recorded at night.展开更多
The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs ...The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.展开更多
The paper analyzed the concentrations of trace metals in fine and respirable particulates (fine-PM<sub>1</sub> and PM<sub>2.5</sub>;respirable-PM<sub>10</sub>) to determine baseline...The paper analyzed the concentrations of trace metals in fine and respirable particulates (fine-PM<sub>1</sub> and PM<sub>2.5</sub>;respirable-PM<sub>10</sub>) to determine baseline concentrations in the ambient air and the factors impacting its distribution such as land use and time of year when levels may be concerning to public health. Measurements of particulates along with meteorological parameters were made at four sites over the heavily populated west coast of Trinidad (10<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span></span>32'N, 61<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span></span>18'W) during March ’15-May ’16, representing rural, urban, mixed background and industrial land uses. The study found mean levels of trace metals to be highest at the industrial and urban stations. Public health exceedances (referenced to the Canadian AAQ public health standards <a href="#ref23">(Ontario-MoE, 2012)</a>) were measured for beryllium, cadmium, chromium, iron, manganese and nickel (in PM<sub>10</sub>). Iron, manganese and nickel, most associated with particulates at the industrial station, were in frequent exceedance. Beryllium—concentrated in coarse PM (PM<sub>2.5-10</sub>) with only a single measured exceedance at the mixed background station likely poses minimal threat to the health of the nearby population. Cadmium—concentrated in fine PM which peaked once only at the rural station was likely due to an irregular event within a narrow timeframe during the time of sampling. Iron and manganese were frequently above the Canadian public health threshold, but predominated in the coarse PM fraction, suggesting localised sources. Nickel, concentrated in the fine PM fraction, was frequently in exceedance particularly at the industrial station. Cadmium and nickel are genotoxic and should be regulated in order to reduce the burden of toxic carcinogens to which the population can be exposed.展开更多
为了探究典型金属粉末对燃料空气炸药(fuel air explosive,FAE)冲击波效应和热毁伤性能的影响,采用20 L球形液体爆炸测试系统并结合比色测温方法,深入研究了不同金属粉种类和含量下环氧丙烷(epoxypropane,PO)的燃爆特性、火焰结构及温...为了探究典型金属粉末对燃料空气炸药(fuel air explosive,FAE)冲击波效应和热毁伤性能的影响,采用20 L球形液体爆炸测试系统并结合比色测温方法,深入研究了不同金属粉种类和含量下环氧丙烷(epoxypropane,PO)的燃爆特性、火焰结构及温度分布特征。实验结果表明:纯环氧丙烷的最佳质量浓度为780 g/m^(3),最大爆燃超压Δp_(max)=0.799 MPa,最大压力上升速率(dp/dt)_(max)=52.438 MPa/s。添加Al粉、Ti粉和Mg粉的环氧丙烷最大燃爆超压、最大压力上升速率和最大火焰平均温度均随着金属粉末质量比(I)的增加而增大,而最大压力上升时间的变化趋势则与之相反;最大燃爆超压和最大火焰平均温度的变化规律一致,从大到小依次为:Al/PO、Mg/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的?pmax值相较于纯环氧丙烷分别增加了12.00%、8.41%和11.54%;此外,最大压力上升速率和燃烧速率的变化规律一致,从大到小依次为:Mg/PO、Al/PO、Ti/PO,且当金属粉的质量比I=40%时,3种固-液混合燃料的(dp/dt)max值相较于纯环氧丙烷分别增加了41.91%、39.60%和45.29%。研究结果表明,不同高能金属粉末在改善环氧丙烷燃爆性能方面各有优势,在FAE的配方设计时,应根据毁伤性能指标合理选择金属粉末作为含能添加剂。展开更多
为了评价实验室空气中金属元素的浓度,开发了一种准确、高效的分析检测方法。将高纯液氩汽化时形成的冷凝冰碴作为样品载体,采用电感耦合等离子体质谱仪(Inductively Coupled Plasma Mass Spectrometry,ICP-MS)测定冷凝冰碴中12种金属...为了评价实验室空气中金属元素的浓度,开发了一种准确、高效的分析检测方法。将高纯液氩汽化时形成的冷凝冰碴作为样品载体,采用电感耦合等离子体质谱仪(Inductively Coupled Plasma Mass Spectrometry,ICP-MS)测定冷凝冰碴中12种金属元素的浓度,建立了一种冷凝收集ICP-MS测定实验室空气中金属元素的方法。该方法冷凝收集率为70.8%~85.8%,各元素线性相关系数R2均大于0.9999,检测限为0.001~0.019μg/L,定量限为0.003~0.063μg/L,6次重复测定的相对标准偏差均小于5%,加标回收率为80.5%~99.2%。该方法操作简便、检测效率高,检测限低,数据线性相关性良好,精密度和准确度良好。采用该方法测定某实验室空气冷凝收集样品中12种金属元素的含量,对比测定结果与标准方法职业接触限值,表明实验室空气中各元素浓度远低于职业接触限值对应浓度,该实验室空气中金属元素污染风险低。所建立的检测方法能准确、快速地测定空气中的多种金属元素含量,为实验室空气的安全性评价提供参考依据。展开更多
文摘This work creates a droplet battery model based on the electrolyte performance in the porous electrode, studies the current density on the mesoscopic scale, and explains how the mesoscopic structure of the porous electrode influences the current density on the air-diffusion electrode. Near the three-phase line, there is a strong band containing nearly 80% current. For porous electrodes, the total current is proportional to the length of the strong band. Thus, it can be inferred that on the macroscopic scale, the longer the total length of the strong band on unit area is, the larger the current density is.
文摘A cement factory nearby communities raise pollution concerns. This study assessed air pollution levels for respirable particulate matter (PM2.5 and PM10) and heavy metals (lead, chromium, nickel, cadmium, zinc and copper) adjacent to a cement factory in Ewekoro and neighbouring communities (Papalantoro, Lapeleko and Itori) in Ogun State, Nigeria. Respirable particulate matter (PM2.5 and PM10) and heavy metals were measured using an ARA N-FRM cassette sampler. Each location sampled was monitored for eight continuous hours daily for 12 days. The PM2.5, PM10 and heavy metals results were compared with different standards, including those of the World Health Organization (WHO), Nigeria’s National Environmental Standard and Regulation Enforcement Agency (NESREA) and Canadian Ambient Air Quality Standards (CAAQS). The PM levels fell within 11 - 19 μg/m3 of the air management level of CAAQS, which signifies continuous actions are needed to improve air quality in the areas monitored but below the NESREA standard. The mean Cd, Cr and Ni concentrations in the cement factory area and the impacted neighbourhoods are higher than the WHO/EU permissible limits, while Zn and Cu were below the WHO/EU permissible limit. A risk assessment hazard quotient (HQ) for Cr was above the WHO/EU safe level (=1) in adults and children throµgh ingestion, inhalation and dermal contact at all the monitoring sites. The HQ for Ni and Cd was higher than the safe level in the cement factory area and Papalantoro, while Zn was at safe levels.
基金supported by NSFC(21473094 and21421001)MOE Innovation Team(IRT13022) in China
文摘Rechargeable alkali metal-air batteries are considered as the most promising candidate for the power source of electric vehicles(EVs) due to their high energy density. However, the practical application of metal-air batteries is still challenging. In the past decade, many strategies have been purposed and explored, which promoted the development of metal-air batteries. The reaction mechanisms have been gradually clarified and catalysts have been rationally designed for air cathodes. In this review, we summarize the recent development of alkali metal-air batteries from four parts: metal anodes, electrolytes, air cathodes and reactant gases, wherein we highlight the important achievement in this filed. Finally problems and prospective are discussed towards the future development of alkali metal-air batteries.
文摘Air pollution present the greatest threat to human health and welfare in urban environments. Population growth, industrial activities, expanded transport system, vehicular traffic, poor road planning, poor land use and traffic congestion contribute to the problem. Particulate matter (PM<sub>2.5</sub> and PM<sub>10</sub>) has become the principal pollutants due to increased material use, energy demand and use as a result of global economic growth. This study assessed the levels of PM<sub>10</sub> in ambient air and heavy metal composition in Nairobi city. Sampling sites were classified into three categories namely;controlled areas, industrial and residential areas as proscribed in the EMCA Air Quality Regulations, 2014. Portable Mini-Vol ambient air samplers were used for fine particulate monitoring. The concentrations of manganese, lead, and cadmium was determined in PM<sub>10</sub> samples from all sampling sites. The lead concentration mean was 0.07 ± 0.06 μg/m<sup>3</sup>, 0.34 ± 0.35 μg/m<sup>3</sup> and 1.10 ± 0.59 μg/m<sup>3</sup> for residential, controlled and industrial areas respectively. Generally, all afternoons had high particulate matter while the lowest concentration levels of PM<sub>10</sub> were recorded at night.
基金The Natural Science Foundation of China (50266063) .
文摘The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.
文摘The paper analyzed the concentrations of trace metals in fine and respirable particulates (fine-PM<sub>1</sub> and PM<sub>2.5</sub>;respirable-PM<sub>10</sub>) to determine baseline concentrations in the ambient air and the factors impacting its distribution such as land use and time of year when levels may be concerning to public health. Measurements of particulates along with meteorological parameters were made at four sites over the heavily populated west coast of Trinidad (10<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span></span>32'N, 61<span style="font-size:10.0pt;font-family:;" "=""><span style="color:#4F4F4F;font-family:"font-size:14px;white-space:normal;background-color:#FFFFFF;">°</span></span>18'W) during March ’15-May ’16, representing rural, urban, mixed background and industrial land uses. The study found mean levels of trace metals to be highest at the industrial and urban stations. Public health exceedances (referenced to the Canadian AAQ public health standards <a href="#ref23">(Ontario-MoE, 2012)</a>) were measured for beryllium, cadmium, chromium, iron, manganese and nickel (in PM<sub>10</sub>). Iron, manganese and nickel, most associated with particulates at the industrial station, were in frequent exceedance. Beryllium—concentrated in coarse PM (PM<sub>2.5-10</sub>) with only a single measured exceedance at the mixed background station likely poses minimal threat to the health of the nearby population. Cadmium—concentrated in fine PM which peaked once only at the rural station was likely due to an irregular event within a narrow timeframe during the time of sampling. Iron and manganese were frequently above the Canadian public health threshold, but predominated in the coarse PM fraction, suggesting localised sources. Nickel, concentrated in the fine PM fraction, was frequently in exceedance particularly at the industrial station. Cadmium and nickel are genotoxic and should be regulated in order to reduce the burden of toxic carcinogens to which the population can be exposed.
文摘为了评价实验室空气中金属元素的浓度,开发了一种准确、高效的分析检测方法。将高纯液氩汽化时形成的冷凝冰碴作为样品载体,采用电感耦合等离子体质谱仪(Inductively Coupled Plasma Mass Spectrometry,ICP-MS)测定冷凝冰碴中12种金属元素的浓度,建立了一种冷凝收集ICP-MS测定实验室空气中金属元素的方法。该方法冷凝收集率为70.8%~85.8%,各元素线性相关系数R2均大于0.9999,检测限为0.001~0.019μg/L,定量限为0.003~0.063μg/L,6次重复测定的相对标准偏差均小于5%,加标回收率为80.5%~99.2%。该方法操作简便、检测效率高,检测限低,数据线性相关性良好,精密度和准确度良好。采用该方法测定某实验室空气冷凝收集样品中12种金属元素的含量,对比测定结果与标准方法职业接触限值,表明实验室空气中各元素浓度远低于职业接触限值对应浓度,该实验室空气中金属元素污染风险低。所建立的检测方法能准确、快速地测定空气中的多种金属元素含量,为实验室空气的安全性评价提供参考依据。
