The main objectives of this study were to introduce an integrated method for effectively identifying soil heavy metal pollution sources and apportioning their contributions, and apply it to a case study. The method co...The main objectives of this study were to introduce an integrated method for effectively identifying soil heavy metal pollution sources and apportioning their contributions, and apply it to a case study. The method combines the principal component analysis/absolute principal component scores (PCA/APCS) receptor model and geostatistics. The case study was conducted in an area of 31 km2 in the urban-rural transition zone of Wuhan, a metropolis of central China. 124 topsoil samples were collected for measuring the concentrations of eight heavy metal elements (Mn, Cu, Zn, Pb, Cd, Cr, Ni and Co). PCA results revealed that three major factors were responsible for soil heavy metal pollution, which were initially identified as "steel production", "agronomic input" and "coal consumption". The APCS technique, combined with multiple linear regression analysis, was then applied for source apportionment. Steel production appeared to be the main source for Ni, Co, Cd, Zn and Mn, agronomic input for Cu, and coal consumption for Pb and Cr. Geostatistical interpolation using ordinary kriging was finally used to map the spatial distributions of the contributions of pollution sources and further confirm the result interpretations. The introduced method appears to be an effective tool in soil pollution source apportionment and identification, and might provide valuable reference information for pollution control and environmental management.展开更多
介绍了主要由通用变频器、PLC、位置控制器、执行机构等组成的异步电动机传动的位置控制系统(APCS-Auto Position Control System),分析了系统的定位过程及工作原理,讨论和提出了减少系统定位偏差和克服死区的补偿方法;简要介绍了国内...介绍了主要由通用变频器、PLC、位置控制器、执行机构等组成的异步电动机传动的位置控制系统(APCS-Auto Position Control System),分析了系统的定位过程及工作原理,讨论和提出了减少系统定位偏差和克服死区的补偿方法;简要介绍了国内外异步电动机定位控制领域的研究发展动态。展开更多
The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The conc...The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.展开更多
Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure.Lymph nodes,which filter the lymph to identify and fight infections,play a central role in this pr...Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure.Lymph nodes,which filter the lymph to identify and fight infections,play a central role in this process.However,careful characterization of the impact of aging on lymph nodes and associated autoimmune diseases is lacking.We combined single-cell RNA sequencing(scRNA-seq)with flow cytometry to delineate the immune cell atlas of cervical draining lymph nodes(CDLNs)of both young and old mice with or without experimental autoimmune uveitis(EAU).We found extensive and complicated changes in the cellular constituents of CDLNs during aging.When confronted with autoimmune challenges,old mice developed milder EAU compared to young mice.Within this EAU process,we highlighted that the pathogenicity of T helper 17 cells(Th17)was dampened,as shown by reduced GM-CSF secretion in old mice.The mitigated secretion of GMCSF contributed to alleviation of IL-23 secretion by antigen-presenting cells(APCs)and may,in turn,weaken APCs’effects on facilitating the pathogenicity of Th17 cells.Meanwhile,our study further unveiled that aging downregulated GM-CSF secretion through reducing both the transcript and protein levels of IL-23R in Th17 cells from CDLNs.Overall,aging altered immune cell responses,especially through toning down Th17 cells,counteracting EAU challenge in old mice.展开更多
While the central nervous system (CNS) was once thought to be immune privileged, more recent data support that certain areas of the healthy CNS are routinely patrolled by immune cells. Further, antigen drainage is ano...While the central nervous system (CNS) was once thought to be immune privileged, more recent data support that certain areas of the healthy CNS are routinely patrolled by immune cells. Further, antigen drainage is another means by which the adaptive arm of the immune system can gain information about the health of the CNS. Altogether these ensure that the CNS is not beyond the scope of immune protection against viruses and tumors. However, immune surveillance in the CNS has to be tightly regulated, as CNS autoimmune disease and inflammation may arise from increased immune cell infiltration. In this review we discuss the concept and implications of CNS immune surveillance and introduce the CNS antigen-presenting cells (APCs) that potentially regulate neuroinflammation and autoimmunity. We also discuss novel animal models in which CNS disease initiation and the role of APCs in disease regulation can be tested.展开更多
本刊讯为了提高制浆和回收工段的稳定性,Navigator集团位于葡萄牙的Cacia工厂(Cacia mill)将在线分析与高级过程控制系统(advanced process controls,APCs)结合起来,提高产量的同时也降低了原料和能源消耗。Cacia工厂年产能37万吨,主要...本刊讯为了提高制浆和回收工段的稳定性,Navigator集团位于葡萄牙的Cacia工厂(Cacia mill)将在线分析与高级过程控制系统(advanced process controls,APCs)结合起来,提高产量的同时也降低了原料和能源消耗。Cacia工厂年产能37万吨,主要生产漂白桉木浆,用于高质量壁纸、滤纸、卷烟纸等多种特种纸生产。展开更多
在太原市运用中流量采样器进行24 h PM_(2.5)样品采集,并进行水溶性有机碳(WSOC)、水溶性总氮(WSTN)、水溶性有机氮(WSON)以及无机离子分析,探究其浓度、组成、时间变化特征与来源。结果表明,冬季采暖期太原PM_(2.5)中WSON日平均浓度为(...在太原市运用中流量采样器进行24 h PM_(2.5)样品采集,并进行水溶性有机碳(WSOC)、水溶性总氮(WSTN)、水溶性有机氮(WSON)以及无机离子分析,探究其浓度、组成、时间变化特征与来源。结果表明,冬季采暖期太原PM_(2.5)中WSON日平均浓度为(10.0±4.9)μg/m^3,平均占WSTN的44%。在无霾天(能见度>10 km)、微霾天(5 km≤能见度≤10 km)和重霾天(能见度<5 km),WSON分别为(1.1±1.0)、(4.3±2.9)、(15.5±4.5)μg/m^3。WSON/WSOC质量比从无霾天、微霾天到重灰霾天呈逐步增大趋势,其均值分别为0.3±0.5、0.47±0.16、0.64±0.15。PCA/APCS模型分析表明,燃煤燃烧、生物质燃烧以及汽车尾气排放的混合源对WSON的贡献率为21.4%,建筑扬尘对WSON的贡献率为1.3%,烹饪对WSON的贡献率为1.7%。展开更多
Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into p...Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.展开更多
基金Supported by the National Natural Science Foundation of China (No. 40971269)
文摘The main objectives of this study were to introduce an integrated method for effectively identifying soil heavy metal pollution sources and apportioning their contributions, and apply it to a case study. The method combines the principal component analysis/absolute principal component scores (PCA/APCS) receptor model and geostatistics. The case study was conducted in an area of 31 km2 in the urban-rural transition zone of Wuhan, a metropolis of central China. 124 topsoil samples were collected for measuring the concentrations of eight heavy metal elements (Mn, Cu, Zn, Pb, Cd, Cr, Ni and Co). PCA results revealed that three major factors were responsible for soil heavy metal pollution, which were initially identified as "steel production", "agronomic input" and "coal consumption". The APCS technique, combined with multiple linear regression analysis, was then applied for source apportionment. Steel production appeared to be the main source for Ni, Co, Cd, Zn and Mn, agronomic input for Cu, and coal consumption for Pb and Cr. Geostatistical interpolation using ordinary kriging was finally used to map the spatial distributions of the contributions of pollution sources and further confirm the result interpretations. The introduced method appears to be an effective tool in soil pollution source apportionment and identification, and might provide valuable reference information for pollution control and environmental management.
基金supported by the ALCA project of Japan Science and Technology Agency.
文摘The pinning of quantized magnetic vortices in superconducting YBa_(2)Cu_(3)O_(7-δ)(YBCO or Y123)thin films with Y_(2)BaCuO_(5)(Y211)nanoinclusions have been investigated over wide temperature range(4.2-77 K).The concentration of Y211 nanoinclusions has been systematically varied inside YBCO thin films prepared by laser ablation technique using surface modified target approach.Large pinning force density values(Fp∼0.5 TNm^(−3)at 4.2 K,9 T)have been observed for the YBCO film with moderate concentration of Y211 nanoinclusions(3.6 area%on ablation target).In addition,uniform enhancement in critical current density(J_(c))was observed in the angular dependent J_(c)measurement of YBCO+Y211 nanocomposite films.Y211 nanoinclusions have been found to be very efficient in pinning the quantized vortices thereby enhancing the in‐field J_(c)values over a wide range of temperature.Increasing the concentration of Y211 secondary phase into Y123 film matrix results into agglomeration of Y211 phase and observed as increased Y211 nanoparticle size.These larger secondary phase nanoparticles are not as efficient pinning centers at lower temperatures as they are at higher temperatures due to substantial reduction of the coherence length at lower temperatures.Investigation of the temperature dependence of J_(c)for YBCO+Y211 nanocomposite films has been conducted and possible vortex pinning mechanism in these nanocomposite films has been discussed.
基金the National Key Research and Development Program of China(2017YFA0105804)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA16010000)+3 种基金the National Key Research and Development Program of China(2020YFA0804000,2018YFC2000100,2017YFA0103304,2020YFA0803401,2019YFA0802202)the National Natural Science Foundation of China(Grant Nos.81921006,81625009,91749202,91949209,81822018,82125011,82122024,31970597)the Key Research Program of the Chinese Academy of Sciences(KFZD-SW-221)the 14th Five-year Network Security and Informatization Plan of Chinese Academy of Sciences(WX145XQ07-18)。
文摘Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure.Lymph nodes,which filter the lymph to identify and fight infections,play a central role in this process.However,careful characterization of the impact of aging on lymph nodes and associated autoimmune diseases is lacking.We combined single-cell RNA sequencing(scRNA-seq)with flow cytometry to delineate the immune cell atlas of cervical draining lymph nodes(CDLNs)of both young and old mice with or without experimental autoimmune uveitis(EAU).We found extensive and complicated changes in the cellular constituents of CDLNs during aging.When confronted with autoimmune challenges,old mice developed milder EAU compared to young mice.Within this EAU process,we highlighted that the pathogenicity of T helper 17 cells(Th17)was dampened,as shown by reduced GM-CSF secretion in old mice.The mitigated secretion of GMCSF contributed to alleviation of IL-23 secretion by antigen-presenting cells(APCs)and may,in turn,weaken APCs’effects on facilitating the pathogenicity of Th17 cells.Meanwhile,our study further unveiled that aging downregulated GM-CSF secretion through reducing both the transcript and protein levels of IL-23R in Th17 cells from CDLNs.Overall,aging altered immune cell responses,especially through toning down Th17 cells,counteracting EAU challenge in old mice.
文摘While the central nervous system (CNS) was once thought to be immune privileged, more recent data support that certain areas of the healthy CNS are routinely patrolled by immune cells. Further, antigen drainage is another means by which the adaptive arm of the immune system can gain information about the health of the CNS. Altogether these ensure that the CNS is not beyond the scope of immune protection against viruses and tumors. However, immune surveillance in the CNS has to be tightly regulated, as CNS autoimmune disease and inflammation may arise from increased immune cell infiltration. In this review we discuss the concept and implications of CNS immune surveillance and introduce the CNS antigen-presenting cells (APCs) that potentially regulate neuroinflammation and autoimmunity. We also discuss novel animal models in which CNS disease initiation and the role of APCs in disease regulation can be tested.
文摘本刊讯为了提高制浆和回收工段的稳定性,Navigator集团位于葡萄牙的Cacia工厂(Cacia mill)将在线分析与高级过程控制系统(advanced process controls,APCs)结合起来,提高产量的同时也降低了原料和能源消耗。Cacia工厂年产能37万吨,主要生产漂白桉木浆,用于高质量壁纸、滤纸、卷烟纸等多种特种纸生产。
文摘Due to development of distribution systems and increase in electricity demand,the use of capacitor banks increases.From the other point of view,nonlinear loads generate and inject considerable harmonic currents into power system.Under this condition if capacitor banks are not properly selected and placed in the power system,they could amplify and propagate these harmonics and deteriorate power quality to unacceptable levels.With attention of disadvantages of passive filters,such as occurring resonance,nowadays the usage of this type of harmonic compensator is restricted.On the other side,one of parallel multi-function compensating devices which are recently used in distribution system to mitigate voltage sag and harmonic distortion,performs power factor correction,and improves the overall power quality as active power conditioner(APC).Therefore,the utilization of APC in harmonic distorted system can affect and change the optimal location and size of shunt capacitor bank under harmonic distortion condition.This paper presents an optimization algorithm for improvement of power quality using simultaneous optimal placement and sizing of APC and shunt capacitor banks in radial distribution networks in the presence of voltage and current harmonics.The algorithm is based on particle swarm optimization(PSO).The objective function includes the cost of power losses,energy losses and those of the capacitor banks and APCs.
