[Objectives]To detect content of Pb,Cd,Hg,As,Cu,Zn,and Cr in Lysimachia christinae,and to analyze the pollution level.[Methods]Seven kinds of elements in L.christinae were determined by Inductively coupled plasma mass...[Objectives]To detect content of Pb,Cd,Hg,As,Cu,Zn,and Cr in Lysimachia christinae,and to analyze the pollution level.[Methods]Seven kinds of elements in L.christinae were determined by Inductively coupled plasma mass spectrometry and analyzed by single index and comprehensive index.[Results]The seven heavy metal elements showed good linearity in their respective concentration ranges.The recoveries of the samples were 84.5%-109.5%,and the RSD values were 2.30%-5.10%.Comparing the measured results of heavy metal elements with the limit values stipulated in the 2020 edition of the Chinese Pharmacopoeia and other standards,the Cr element in 19 batches of samples exceeded the standard,and the Zn element in 7 batches of samples exceeded the standard.The exceeding rates were 100.0%and 36.8%,respectively;the content of other heavy metal elements did not exceed the standard.The order of individual index from large to small was Cr,Zn,Cd,Hg,Cu,As,and Pb,and the average comprehensive pollution level was mild pollution and above.[Conclusions]L.christinae was mainly polluted by Cr,followed by Zn;this study can provide basic data for drafting of the limit standard for heavy metal elements in L.christinae.展开更多
[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F...[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F.thunbergii Miq.introduced to different places.[Methods]F.thunbergii Miq.from four different provenances including Zhejiang,Nantong and Chongqing were introduced and cultivated in Wanzhou of Chongqing.The contents of available Zn,Fe,Mn,Cu,Mo,N,P,K,Ca and Mg in rhizosphere soil of F.thunbergii Miq.during five growing stages were determined after selecting different stem sizes for field cultivation.[Results]Small stems of Pan an and Ningbo provenances(SSG3,121-160/kg)and middle stems of Nantong and Fengjie provenances(SSG2,81-120/kg)showed higher soil availability.[Conclusions]In the process of introduction and cultivation of F.thunbergii Miq.,high yield and high efficiency can be achieved by selecting smaller seed stems of F.thunbergii Miq.展开更多
Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increas...Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increases in agricultural production costs.This article reviews the research and application progress of mechanized rice direct seeding including direct seeding technologies,precision rice seeding,precision rice seed-metering devices,key supporting agronomy technologies for mechanized rice direct seeding.South China Agricultural University developed precision rice hill-drop drilling(PRHDD)with synchronous furrowing and ridging technology and series machines for paddy that affords remarkable advantages in terms of saving time and labour,higher yield,and higher efficiency.In this approach,pre-germinated seeds are uniformly hill-dropped in the expected positions in puddled soil.It significantly improved the crop growth population and effectively solved the problems of high frequency of disease and pests caused by the irregular distribution of rice seeds with manual broadcasting,and generally reduces seed usage and increases the yield.Therefore,this technology has broad application prospects and great potential for promoting the development of mechanized rice direct seeding in China.展开更多
To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that...To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.展开更多
Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a ...Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a nanoneedle material: γ-(AlOOH@FeOOH)(γ-Al@Fe).The physicochemical properties of γ-Al@Fe were thoroughly characterized, and its effectiveness as a catalyst for photocatalytic reduction of Cr(Ⅵ) was evaluated.The results showed that Cr(Ⅵ) could be efficiently reduced by γ-Al@Fe in the presence of tartaric acid(TA) under visible light.The variable factors on the reaction were investigated in detail, and the results showed that under optimal conditions(γ-Al@Fe 0.4 g/L, TA 0.6 g/L, pH 2), Cr(Ⅵ)was completely reduced within 7 min.Besides, scavenger experiments and EPR proved that O_(2)^(·-) and CO_(2)^(·-) played a significant role in the photocatalytic reduction of Cr(Ⅵ).TA acts as a sacrificial agent to trap the holes and generate strong reducing free radicals: CO_(2)^(·-).Dissolving O_(2) could react with electrons to generate O_(2)^(·-).This work discussed the performance and mechanism of photocatalytic reduction of Cr(Ⅵ) in detail, which provided a new idea for the resource utilization of solid waste and the treatment of heavy metal sewage.展开更多
基金Supported by Risk Monitoring Task Project of Chongqing Drug Administration in 2020。
文摘[Objectives]To detect content of Pb,Cd,Hg,As,Cu,Zn,and Cr in Lysimachia christinae,and to analyze the pollution level.[Methods]Seven kinds of elements in L.christinae were determined by Inductively coupled plasma mass spectrometry and analyzed by single index and comprehensive index.[Results]The seven heavy metal elements showed good linearity in their respective concentration ranges.The recoveries of the samples were 84.5%-109.5%,and the RSD values were 2.30%-5.10%.Comparing the measured results of heavy metal elements with the limit values stipulated in the 2020 edition of the Chinese Pharmacopoeia and other standards,the Cr element in 19 batches of samples exceeded the standard,and the Zn element in 7 batches of samples exceeded the standard.The exceeding rates were 100.0%and 36.8%,respectively;the content of other heavy metal elements did not exceed the standard.The order of individual index from large to small was Cr,Zn,Cd,Hg,Cu,As,and Pb,and the average comprehensive pollution level was mild pollution and above.[Conclusions]L.christinae was mainly polluted by Cr,followed by Zn;this study can provide basic data for drafting of the limit standard for heavy metal elements in L.christinae.
基金Supported by Technological Innovation and Application Demonstration Project of Chongqing City(cstc2018jscx-msybX0367).
文摘[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F.thunbergii Miq.introduced to different places.[Methods]F.thunbergii Miq.from four different provenances including Zhejiang,Nantong and Chongqing were introduced and cultivated in Wanzhou of Chongqing.The contents of available Zn,Fe,Mn,Cu,Mo,N,P,K,Ca and Mg in rhizosphere soil of F.thunbergii Miq.during five growing stages were determined after selecting different stem sizes for field cultivation.[Results]Small stems of Pan an and Ningbo provenances(SSG3,121-160/kg)and middle stems of Nantong and Fengjie provenances(SSG2,81-120/kg)showed higher soil availability.[Conclusions]In the process of introduction and cultivation of F.thunbergii Miq.,high yield and high efficiency can be achieved by selecting smaller seed stems of F.thunbergii Miq.
基金The authors wish to acknowledge the funding from National Postdoctoral Program for Innovative Talents(BX201700083)Introduction of the International Advanced Agricultural Science and Technology Program(948 plan)(Project No.2016-X24)+1 种基金Commonweal Project(Project No.201203059)13th Five-year Plan National Key Research Program(Project No.2017YFD0700503-2).
文摘Mechanized rice direct seeding is a cost-effective and efficient approach for rice cultivation.Recently,the use of rice direct seeding has been increasing rapidly owing to rural labour shortages and continuous increases in agricultural production costs.This article reviews the research and application progress of mechanized rice direct seeding including direct seeding technologies,precision rice seeding,precision rice seed-metering devices,key supporting agronomy technologies for mechanized rice direct seeding.South China Agricultural University developed precision rice hill-drop drilling(PRHDD)with synchronous furrowing and ridging technology and series machines for paddy that affords remarkable advantages in terms of saving time and labour,higher yield,and higher efficiency.In this approach,pre-germinated seeds are uniformly hill-dropped in the expected positions in puddled soil.It significantly improved the crop growth population and effectively solved the problems of high frequency of disease and pests caused by the irregular distribution of rice seeds with manual broadcasting,and generally reduces seed usage and increases the yield.Therefore,this technology has broad application prospects and great potential for promoting the development of mechanized rice direct seeding in China.
基金funding from National key research program(Project No.2017YFD07000700,2017YFD07000704)Commonweal Project(Project No.201203059)+1 种基金National Natural Science Foundation of China(Project No.51105147)Foundation of Guangdong Province of China(Project No.S2011010001948).
文摘To address the clogging of the rice seed metering device after a long period of operation without affecting the precision of normal seeding,an active seed throwing and cleaning unit was designed based on the fact that magnets of the same pole were mutually exclusive.The working principle of the two devices was analysed theoretically,and a mechanical model was created according to the relationship between the repulsion forces of magnets and the spring forces of springs.The super hybrid rice Y-2 You 900 with 22.5%moisture content(wet basis)was used as the test object.The whole factor experiments were carried out under different negative pressures,rotational speeds of the suction plates,and lengths of probes.The results indicated that under any test conditions,the active seed throwing and cleaning unit worked normally.The results of high-speed photography showed that the rate of seed cleaning was 100%.The results also showed that the optimal negative pressure was 0.8 kPa.The probability of 1-3 seeds per hill for the seed metering device was approximately 95%under the optimal negative pressure.The optimal length of the probe was found to be 2 mm.The average qualified rate of hill space was 96.04%under the optimal length of probe,the longer the length of the probe,the lower the qualified rate of hill space.It also showed that an active seed throwing and cleaning unit could effectively avoid the hole clogging caused by the long-term operation and had no influence on the normal operation of the pneumatic rice seed metering device.The active seed throwing and cleaning unit improved the stability of the seed metering device,and the research provided a reference for the optimal design of seed throwing and cleaning structures of the pneumatic rice seed metering device.
基金supported by the National Natural Science Foundation of China (Nos.51672077, 51872089)。
文摘Cr(Ⅵ) is a common heavy metal ion, which will seriously harm human body and environment.Therefore, the removal of Cr(Ⅵ) has become an attractive topic.In this work, cinder was used as a raw material to synthesize a nanoneedle material: γ-(AlOOH@FeOOH)(γ-Al@Fe).The physicochemical properties of γ-Al@Fe were thoroughly characterized, and its effectiveness as a catalyst for photocatalytic reduction of Cr(Ⅵ) was evaluated.The results showed that Cr(Ⅵ) could be efficiently reduced by γ-Al@Fe in the presence of tartaric acid(TA) under visible light.The variable factors on the reaction were investigated in detail, and the results showed that under optimal conditions(γ-Al@Fe 0.4 g/L, TA 0.6 g/L, pH 2), Cr(Ⅵ)was completely reduced within 7 min.Besides, scavenger experiments and EPR proved that O_(2)^(·-) and CO_(2)^(·-) played a significant role in the photocatalytic reduction of Cr(Ⅵ).TA acts as a sacrificial agent to trap the holes and generate strong reducing free radicals: CO_(2)^(·-).Dissolving O_(2) could react with electrons to generate O_(2)^(·-).This work discussed the performance and mechanism of photocatalytic reduction of Cr(Ⅵ) in detail, which provided a new idea for the resource utilization of solid waste and the treatment of heavy metal sewage.
