The heavy metals in atmospheric fine particles are of great concern to human health. To understand the pollution characteristics and health risks of heavy metals in particulate matter with an aerodynamic equivalent di...The heavy metals in atmospheric fine particles are of great concern to human health. To understand the pollution characteristics and health risks of heavy metals in particulate matter with an aerodynamic equivalent diameter ≤2.5 μm (PM<sub>2.5</sub>) during winter in the suburb of Cangzhou, PM<sub>2.5</sub> samples were collected with an intelligent medium-flow atmospheric particulate matter sampler from January to February 2019. The Fe, Cu, Mn, Pb and Zn contents in PM<sub>2.5</sub> were determined via inductively coupled plasma optical emission spectrometry (ICP-OES). The sources and health risks of heavy metals in PM<sub>2.5</sub> were analysed via the enrichment factor (EF) method and the United States Environmental Protection Agency (US EPA) health risk assessment model. The results showed that the average PM<sub>2.5</sub> concentration in the suburb of Cangzhou reached 71.6 μg/m<sup>3</sup>, ranging from 23.7 to 169.5 μg/m<sup>3</sup>. The exceeding standard rate was 29.4% during the sampling period. The PM<sub>2.5</sub> concentration during the nighttime was higher than that during the daytime. The heavy metal concentrations in PM<sub>2.5</sub> decreased in the order of Fe > Mn > Zn > Cu > Pb, and the Fe, Mn, Pb and Zn concentrations decreased in the order of clean days < pollution days < heavy pollution days. The Fe and Mn concentrations were higher during the daytime than those during the nighttime, while the Cu, Pb and Zn concentrations were higher during the nighttime than those during the daytime. EF analysis revealed that Zn, Pb and Cu were significantly enriched, and Pb was highly enriched on heavy pollution days with increasing pollution degree. The enrichment level of heavy metals during the nighttime was higher than that during the daytime. Health risk assessment demonstrated that Mn posed non-carcinogenic risks to both adults and children, following the sequence of clean days < pollution days < heavy pollution days. Pb posed a carcinogenic risk to adults on heavy pollution days. The study revealed that the pollution levels of heavy metals in PM<sub>2.5</sub> in the suburb of Cangzhou were low, and Pb and Mn in PM<sub>2.5</sub> posed certain health risks to the population.展开更多
It is greatly desired to develop novel gadolinium-based contrast agents(GBCAs)as improved platforms for magnetic resonance imaging(MRI).Herein,we report the syntheses of a series of nonionic cyclenbased GBCAs by preci...It is greatly desired to develop novel gadolinium-based contrast agents(GBCAs)as improved platforms for magnetic resonance imaging(MRI).Herein,we report the syntheses of a series of nonionic cyclenbased GBCAs by precisely tuning carboxylate group on DO3A-pyridine scaffold.[Gd-DO3A-4cp]is isolated which adopts an octadentate coordination mode with a free carboxylate group at 4-position of pyridine.It shows the r_(1)relaxivity of 5.8(mmol/L)^(-1)s^(-1)(3 T,25℃),which is 75%higher than 3.3(mmol/L)^(-1)s^(-1)of the clinic used[Gd-DOTA].The possible mechanisms behind the enhanced relaxivity are investigated and proposed by structure-property relationship studies.After validation of low cytotoxicity and considerable kinetic inertness,in-vivo studies are further examined,demonstrating its good MRI performance,biodistribution as well as the way of excretion.展开更多
[Objectives]To study the variation in main chemical composition of Blumea balsamifera in different growth stages,and to provide a theoretical basis to determine appropriate harvest period.[Methods]The l-borneol of the...[Objectives]To study the variation in main chemical composition of Blumea balsamifera in different growth stages,and to provide a theoretical basis to determine appropriate harvest period.[Methods]The l-borneol of the plant was determined by gas chromatography( GC)with methyl salicylate as internal standard,and total flavonoids were determined by the Aluminum nitrate colorimetry method of Ultraviolet-Visible spectrophotometry. The analysis of variance was used for statistical analysis of the l-borneol and total flavonoids of B. balsamifera in different months and different plant age.[Results]There were differences in chemical ingredients of B. balsamifera in different months of the year.The content of l-borneol in October was the highest,but there was no significant difference from August to December in l-borneol content( P >0. 05). l-borneol content of B. balsamifera in three ages was the highest compared with other ages,and there was a significant difference with B. balsamifera in one year or less( P < 0. 05). Relatively speaking,total flavonoids in June,August and November were higher; total flavonoids content of B. balsamifera in two ages was the highest compared with other ages,and there was a significant difference with other ages( P <0. 05).[Conclusions]If l-borneol is taken as an indicator,for extracting Aipan( l-borneol),it can be harvested from September to midDecember,but October is the best. And it can be harvested at least three years. If the content of total flavonoids is taken as an indicator,it should be harvested in November. And it can be harvested 2-3 years.展开更多
Porous materials bearing stepwise-controlled pore-shape change that are capable of executing sophisticated tasks are of considerable interest due to their fascinating features.In this work,we present a(3,4,6)-connecte...Porous materials bearing stepwise-controlled pore-shape change that are capable of executing sophisticated tasks are of considerable interest due to their fascinating features.In this work,we present a(3,4,6)-connected metal–organic framework built of 1D hinge-like zig–zag chain and tritopic ligand,formulated as(H_(3)O)_(2)[Zn_(3)(dmtrz)_(2)(tipa)_(2)]·4H_(2)O(MAC-20,Hdmtrz=3,5-dimethyl-1H-1,2,4-triazole,H_(3)tipa=5-(2Htetrazol-5-yl)isophthalic acid).By regulating the hinge angle and hydrogen bond interaction of 1D chain and tritopic ligand precisely,we realize a unique two-step pore-shape change in MAC-20 structure,which reveals that 1D chain and tritopic ligands have a synergistic effect on the structural transformation.Furthermore,the MAC-20 structure executes the sequential adsorption of indigo blue(ID)and sudan-I(SD-I)stepwise-controlled by trimethylamine and N,N-dimethylformamide,which offers the potential to exploit the flexible MOFs for smart multi-step stimuli-responsive applications.展开更多
Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a po...Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal–organic–frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni^(2+) and Fe^(3+). This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO_(2). This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm^(–2) and a small Tafel slope of 84.4 mV·dec^(–1) in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.展开更多
文摘The heavy metals in atmospheric fine particles are of great concern to human health. To understand the pollution characteristics and health risks of heavy metals in particulate matter with an aerodynamic equivalent diameter ≤2.5 μm (PM<sub>2.5</sub>) during winter in the suburb of Cangzhou, PM<sub>2.5</sub> samples were collected with an intelligent medium-flow atmospheric particulate matter sampler from January to February 2019. The Fe, Cu, Mn, Pb and Zn contents in PM<sub>2.5</sub> were determined via inductively coupled plasma optical emission spectrometry (ICP-OES). The sources and health risks of heavy metals in PM<sub>2.5</sub> were analysed via the enrichment factor (EF) method and the United States Environmental Protection Agency (US EPA) health risk assessment model. The results showed that the average PM<sub>2.5</sub> concentration in the suburb of Cangzhou reached 71.6 μg/m<sup>3</sup>, ranging from 23.7 to 169.5 μg/m<sup>3</sup>. The exceeding standard rate was 29.4% during the sampling period. The PM<sub>2.5</sub> concentration during the nighttime was higher than that during the daytime. The heavy metal concentrations in PM<sub>2.5</sub> decreased in the order of Fe > Mn > Zn > Cu > Pb, and the Fe, Mn, Pb and Zn concentrations decreased in the order of clean days < pollution days < heavy pollution days. The Fe and Mn concentrations were higher during the daytime than those during the nighttime, while the Cu, Pb and Zn concentrations were higher during the nighttime than those during the daytime. EF analysis revealed that Zn, Pb and Cu were significantly enriched, and Pb was highly enriched on heavy pollution days with increasing pollution degree. The enrichment level of heavy metals during the nighttime was higher than that during the daytime. Health risk assessment demonstrated that Mn posed non-carcinogenic risks to both adults and children, following the sequence of clean days < pollution days < heavy pollution days. Pb posed a carcinogenic risk to adults on heavy pollution days. The study revealed that the pollution levels of heavy metals in PM<sub>2.5</sub> in the suburb of Cangzhou were low, and Pb and Mn in PM<sub>2.5</sub> posed certain health risks to the population.
基金financial support from National Natural Science Foundation of China(No.21971045)National Key Technologies R&D Program of China(No.2017YFA0205103)。
文摘It is greatly desired to develop novel gadolinium-based contrast agents(GBCAs)as improved platforms for magnetic resonance imaging(MRI).Herein,we report the syntheses of a series of nonionic cyclenbased GBCAs by precisely tuning carboxylate group on DO3A-pyridine scaffold.[Gd-DO3A-4cp]is isolated which adopts an octadentate coordination mode with a free carboxylate group at 4-position of pyridine.It shows the r_(1)relaxivity of 5.8(mmol/L)^(-1)s^(-1)(3 T,25℃),which is 75%higher than 3.3(mmol/L)^(-1)s^(-1)of the clinic used[Gd-DOTA].The possible mechanisms behind the enhanced relaxivity are investigated and proposed by structure-property relationship studies.After validation of low cytotoxicity and considerable kinetic inertness,in-vivo studies are further examined,demonstrating its good MRI performance,biodistribution as well as the way of excretion.
基金Supported by Project of Central Public-interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences(No.1630032017064)
文摘[Objectives]To study the variation in main chemical composition of Blumea balsamifera in different growth stages,and to provide a theoretical basis to determine appropriate harvest period.[Methods]The l-borneol of the plant was determined by gas chromatography( GC)with methyl salicylate as internal standard,and total flavonoids were determined by the Aluminum nitrate colorimetry method of Ultraviolet-Visible spectrophotometry. The analysis of variance was used for statistical analysis of the l-borneol and total flavonoids of B. balsamifera in different months and different plant age.[Results]There were differences in chemical ingredients of B. balsamifera in different months of the year.The content of l-borneol in October was the highest,but there was no significant difference from August to December in l-borneol content( P >0. 05). l-borneol content of B. balsamifera in three ages was the highest compared with other ages,and there was a significant difference with B. balsamifera in one year or less( P < 0. 05). Relatively speaking,total flavonoids in June,August and November were higher; total flavonoids content of B. balsamifera in two ages was the highest compared with other ages,and there was a significant difference with other ages( P <0. 05).[Conclusions]If l-borneol is taken as an indicator,for extracting Aipan( l-borneol),it can be harvested from September to midDecember,but October is the best. And it can be harvested at least three years. If the content of total flavonoids is taken as an indicator,it should be harvested in November. And it can be harvested 2-3 years.
基金financial support from the Natural Science Foundation of Shanghai(Grant 18ZR1402900)National Natural Science Foundation of China(No.21971045)+1 种基金National Key Technologies R&D Program of China(2017YFA0205103)Shanghai Leading Academic Discipline Project(B108).
文摘Porous materials bearing stepwise-controlled pore-shape change that are capable of executing sophisticated tasks are of considerable interest due to their fascinating features.In this work,we present a(3,4,6)-connected metal–organic framework built of 1D hinge-like zig–zag chain and tritopic ligand,formulated as(H_(3)O)_(2)[Zn_(3)(dmtrz)_(2)(tipa)_(2)]·4H_(2)O(MAC-20,Hdmtrz=3,5-dimethyl-1H-1,2,4-triazole,H_(3)tipa=5-(2Htetrazol-5-yl)isophthalic acid).By regulating the hinge angle and hydrogen bond interaction of 1D chain and tritopic ligand precisely,we realize a unique two-step pore-shape change in MAC-20 structure,which reveals that 1D chain and tritopic ligands have a synergistic effect on the structural transformation.Furthermore,the MAC-20 structure executes the sequential adsorption of indigo blue(ID)and sudan-I(SD-I)stepwise-controlled by trimethylamine and N,N-dimethylformamide,which offers the potential to exploit the flexible MOFs for smart multi-step stimuli-responsive applications.
基金financial support from the National Key Technologies R&D Program of China(Grant No.2017YFA0205103)the National Natural Science Foundation of China(Grant No.21971045)+1 种基金the Natural Science Foundation of Shanghai(Grant No.18ZR1402900)Shanghai Leading Academic Discipline Project(Grant No.B108).
文摘Improvement of the low-cost transition metal electrocatalyst used in sluggish oxygen evolution reaction is a significant but challenging problem. In this study, ultrafine Fe-modulated Ni nanoparticles embedded in a porous Ni-doped carbon matrix were produced by the pyrolysis of zirconium metal–organic–frameworks, in which 2,2′-bipyridine-5,5′-dicarboxylate operating as a ligand can coordinate with Ni^(2+) and Fe^(3+). This strategy allows formation of Fe-modulated Ni nanoparticles with a uniform dimension of about 2 nm which can be ascribed to the spatial blocking effect of ZrO_(2). This unique catalyst displays an efficient oxygen evolution reaction electrocatalytic activity with a low overpotential of 372 mV at 10 mA·cm^(–2) and a small Tafel slope of 84.4 mV·dec^(–1) in alkaline media. More importantly, it shows superior durability and structural stability after 43 h in a chronoamperometry test. Meanwhile, it shows excellent cycling stability during 4000 cyclic voltammetry cycles. This research offers a new insight into the construction of uniform nanoscale transition metals and their alloys as highly efficient and durable electrocatalysts.
