Cadmium(Cd)is one of the most toxic heavy metals in the environment.Atmospheric deposition has been found to be the main source of Cd pollution of soil on a large scale in China,and identification of the relationships...Cadmium(Cd)is one of the most toxic heavy metals in the environment.Atmospheric deposition has been found to be the main source of Cd pollution of soil on a large scale in China,and identification of the relationships between anthropogenic emission,atmospheric deposition,and Cd accumulation in soil is important for developing ways to mitigate Cd non-point pollution.In this study,the relationship between atmospheric emission,atmospheric deposition,and soil Cd accumulation in the Middle-Lower Yangtze Plain in China was investigated using datasets of atmospheric emission,deposition,and soil accumulation from the literatures published between 2000 and 2020.The results showed that the soil Cd accumulation rate in the study area exceeded the national average(4.0μg kg^(–1)yr^(–1))and continued to accumulate in recent decades,although the average accumulation rate decreased from 9.45μg kg^(–1)yr^(–1)(2000–2010 period)to8.86μg kg^(–1)yr^(–1)(2010–2020 period).The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22–29%,with the atmospheric deposition flux decreasing from 0.54 mg m^(–2)yr^(–1)(2000–2010)to 0.48 mg m^(–2)yr^(–1)(2010–2020),both values being greater than the national average.Atmospheric Cd deposition and emission were highly correlated in a provincial administrative region,which is close to a ratio of 1.0.Emission factors may be in a state of dynamic change due to the influences of new Cd emission control technologies and environmental policies.As the main sources of Cd emissions,dust,and smoke emissions per ton of non-ferrous metal production decreased by 64.7%between the 2000–2010 and 2010–2020 periods.Although new environmental policies have been instigated,atmospheric emission of Cd is still excessive.It was hoped that the findings of this work would provide a scientific basis for the rational control of atmospheric emissions and Cd pollution of soil.展开更多
近年来,中性粒细胞与淋巴细胞比值(neutrophil to lymphocyte ratio,NLR)已被公认为一种新型预测生物标志物,由于其创伤小、经济、简便、敏感性和特异性高等优点,在心血管疾病、肾脏疾病、自身免疫性疾病等预后指标中广泛应用。血液透析...近年来,中性粒细胞与淋巴细胞比值(neutrophil to lymphocyte ratio,NLR)已被公认为一种新型预测生物标志物,由于其创伤小、经济、简便、敏感性和特异性高等优点,在心血管疾病、肾脏疾病、自身免疫性疾病等预后指标中广泛应用。血液透析(haemodialysis,HD)作为危重症或晚期肾病患者延长寿命的治疗手段,不可避免会导致很多并发症,因此及时识别和治疗HD相关并发症至关重要。有研究发现在HD相关并发症中NLR似乎具有一定的识别和预测能力,故本综述通过总结当前HD患者相关并发症中NLR研究进展,为临床医生评估HD患者相关并发症的发生和预后提供依据。展开更多
在基于SDN架构的混合卫星网络上讨论了服务功能链(Service Function Chain,SFC)的可靠性部署问题,首先对SFC可靠性保护的问题进行描述,建立了底层网络与SFC请求模型,然后建立了网络服务功能的可靠性需求模型与低轨卫星链路的可靠性需求...在基于SDN架构的混合卫星网络上讨论了服务功能链(Service Function Chain,SFC)的可靠性部署问题,首先对SFC可靠性保护的问题进行描述,建立了底层网络与SFC请求模型,然后建立了网络服务功能的可靠性需求模型与低轨卫星链路的可靠性需求模型,明确了优化目标与约束条件。接着提出基于可靠性的卫星服务功能链保护方法,包括基于深度强化学习的可靠性保护算法和基于低轨卫星节点与链路可靠性备份算法。实验表明,提出的基于可靠性的卫星服务功能链保护方法能在SDN架构的混合卫星网络上提高SFC请求接受率,减少平均时延,在不同的SFC可靠性需求的条件下也保持较高的请求接受率。展开更多
长波红外差分干涉仪在低温工况下会因光学元件受到非均匀应力作用产生干涉条纹的畸变,从而降低干涉仪系统性能。本文为解决低温工况干涉条纹弯曲畸变问题,基于长波红外差分干涉仪光机系统进行了干涉条纹畸变影响因素分析,结合光-机-热...长波红外差分干涉仪在低温工况下会因光学元件受到非均匀应力作用产生干涉条纹的畸变,从而降低干涉仪系统性能。本文为解决低温工况干涉条纹弯曲畸变问题,基于长波红外差分干涉仪光机系统进行了干涉条纹畸变影响因素分析,结合光-机-热耦合分析方法,对干涉仪系统低温工作状态进行仿真。随后设计了针对影响条纹畸变的关键元件——光栅元件的低温微应力动态稳定支撑安装结构,结构优化后的光栅表面面形均方根(Root Mean Square,RMS)值为3.89×10^(-2) nm,面形峰谷值(Peak to Valley,PV)值为2.21×10^(-1) nm,分别较优化前初始系统的分析结果减小了5个数量级,系统仿真干涉条纹畸变小于1个探测器像元。全系统低温验证试验表明,优化结构可有效抑制干涉条纹畸变,畸变量小于2个探测器像元,试验与仿真计算结果一致性较好,验证了优化分析方法的有效性。该优化方案对提升反射式光学系统结构低温稳定性,提高系统工作能力有较大意义和价值。展开更多
基金the Science and Technology Development Fund,Macao SAR,China(0159/2019/A3,001/2022/NIF and 0008/2022/AFJ)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province,China(2019B121205004)。
文摘Cadmium(Cd)is one of the most toxic heavy metals in the environment.Atmospheric deposition has been found to be the main source of Cd pollution of soil on a large scale in China,and identification of the relationships between anthropogenic emission,atmospheric deposition,and Cd accumulation in soil is important for developing ways to mitigate Cd non-point pollution.In this study,the relationship between atmospheric emission,atmospheric deposition,and soil Cd accumulation in the Middle-Lower Yangtze Plain in China was investigated using datasets of atmospheric emission,deposition,and soil accumulation from the literatures published between 2000 and 2020.The results showed that the soil Cd accumulation rate in the study area exceeded the national average(4.0μg kg^(–1)yr^(–1))and continued to accumulate in recent decades,although the average accumulation rate decreased from 9.45μg kg^(–1)yr^(–1)(2000–2010 period)to8.86μg kg^(–1)yr^(–1)(2010–2020 period).The contribution of atmospheric deposition flux to Cd increment in the soil was in the range of 22–29%,with the atmospheric deposition flux decreasing from 0.54 mg m^(–2)yr^(–1)(2000–2010)to 0.48 mg m^(–2)yr^(–1)(2010–2020),both values being greater than the national average.Atmospheric Cd deposition and emission were highly correlated in a provincial administrative region,which is close to a ratio of 1.0.Emission factors may be in a state of dynamic change due to the influences of new Cd emission control technologies and environmental policies.As the main sources of Cd emissions,dust,and smoke emissions per ton of non-ferrous metal production decreased by 64.7%between the 2000–2010 and 2010–2020 periods.Although new environmental policies have been instigated,atmospheric emission of Cd is still excessive.It was hoped that the findings of this work would provide a scientific basis for the rational control of atmospheric emissions and Cd pollution of soil.
文摘近年来,中性粒细胞与淋巴细胞比值(neutrophil to lymphocyte ratio,NLR)已被公认为一种新型预测生物标志物,由于其创伤小、经济、简便、敏感性和特异性高等优点,在心血管疾病、肾脏疾病、自身免疫性疾病等预后指标中广泛应用。血液透析(haemodialysis,HD)作为危重症或晚期肾病患者延长寿命的治疗手段,不可避免会导致很多并发症,因此及时识别和治疗HD相关并发症至关重要。有研究发现在HD相关并发症中NLR似乎具有一定的识别和预测能力,故本综述通过总结当前HD患者相关并发症中NLR研究进展,为临床医生评估HD患者相关并发症的发生和预后提供依据。
文摘在基于SDN架构的混合卫星网络上讨论了服务功能链(Service Function Chain,SFC)的可靠性部署问题,首先对SFC可靠性保护的问题进行描述,建立了底层网络与SFC请求模型,然后建立了网络服务功能的可靠性需求模型与低轨卫星链路的可靠性需求模型,明确了优化目标与约束条件。接着提出基于可靠性的卫星服务功能链保护方法,包括基于深度强化学习的可靠性保护算法和基于低轨卫星节点与链路可靠性备份算法。实验表明,提出的基于可靠性的卫星服务功能链保护方法能在SDN架构的混合卫星网络上提高SFC请求接受率,减少平均时延,在不同的SFC可靠性需求的条件下也保持较高的请求接受率。
文摘长波红外差分干涉仪在低温工况下会因光学元件受到非均匀应力作用产生干涉条纹的畸变,从而降低干涉仪系统性能。本文为解决低温工况干涉条纹弯曲畸变问题,基于长波红外差分干涉仪光机系统进行了干涉条纹畸变影响因素分析,结合光-机-热耦合分析方法,对干涉仪系统低温工作状态进行仿真。随后设计了针对影响条纹畸变的关键元件——光栅元件的低温微应力动态稳定支撑安装结构,结构优化后的光栅表面面形均方根(Root Mean Square,RMS)值为3.89×10^(-2) nm,面形峰谷值(Peak to Valley,PV)值为2.21×10^(-1) nm,分别较优化前初始系统的分析结果减小了5个数量级,系统仿真干涉条纹畸变小于1个探测器像元。全系统低温验证试验表明,优化结构可有效抑制干涉条纹畸变,畸变量小于2个探测器像元,试验与仿真计算结果一致性较好,验证了优化分析方法的有效性。该优化方案对提升反射式光学系统结构低温稳定性,提高系统工作能力有较大意义和价值。
