In order to characterize the oxygen isotopic composition of internal phosphate and explore the possibility of using these data to identify phosphate sources, we measured oxygen isotopic compositions of phosphate(δ^(1...In order to characterize the oxygen isotopic composition of internal phosphate and explore the possibility of using these data to identify phosphate sources, we measured oxygen isotopic compositions of phosphate(δ^(18)O_p) in sediment pore water in Hongfeng Lake, a typical deep-water lake in a mountainous area. These data, in combination with δ^(18)O_p in surface water samples and water column samples, were successfully used to identify phosphate sources. The δ^(18)O_p value of sediment pore water ranged from 15.2% to 15.8%, with an average value of 15.5%—the δ^(18)O_p value of internal phosphate. The δ^(18)O_p values decreased gradually through the water column from 19.4% in surface water to 16.4% in deeper water, implying that internal phosphate had more negative δ^(18)O_p values than external phosphate. This finding was substantiated by horizontal variations in δ^(18)O_p values, which decreased with increasing distance from inflowing rivers. All collected evidence suggests that external and internal phosphate have distinctly different isotopic signatures and that these signatures have not been considerably altered by biological mediation in Hongfeng Lake. Therefore, δ^(18)O_p can be used to distinguish phosphate sources. A two-endmember mixing model showed that internal phosphate had an average contribution of 40%, highlighting the influence of internal phosphorus loading on aqueous phosphate and eutrophication. This study illustrates the need to reduce the internal phosphorus load from sediment and provides guidance for nutrient management and in-lake restoration treatment in Hongfeng Lake. The data presented here are limited, but serve to highlight the great potential of δ^(18)O_p as an effective tracer for identifying phosphate sources. Systematic investigations of the oxygen isotopic compositions of external phosphate, internal phosphate, and phosphate through the water column, in combination with in-lake P biogeochemical cycle study, would be desirable in further research.展开更多
Phosphorus(P) species in surface sediments from a shallow,hypertrophic lake,Lake Dianchi,China,were investigated by P fractionation and ^(31)P nuclear magnetic resonance(NMR) spectroscopy during a regional algal bloom...Phosphorus(P) species in surface sediments from a shallow,hypertrophic lake,Lake Dianchi,China,were investigated by P fractionation and ^(31)P nuclear magnetic resonance(NMR) spectroscopy during a regional algal bloom.In addition,their potential contributions to the overlying water were also evaluated.Labile fractions of P extracted by NH_4C1,bicarbonate dithionite and NaOH ranged from 340.6 to 1,725.8 mg kg^(-1),accounting for20.5%-67.2%of the total P.A two-step extraction method refinement of P recovery was performed before the^(31)P NMR analysis.Recovery rates of sedimentary TP and organic P,by combining EDTA pretreatment and NaOH or mixed reagents,ranged from 31.8%to 69.3%and from19.8%to 51.7%.^(31)P NMR results showed that ortho-P and monoester-P were the most abundant P components in the sediment extractable P of sediments,followed by diester-P and pyro-P.Spatial distribution of the sum of ortho-P,diester-P and pyro-P detected by P NMR corresponded well with the labile P concentration determined by fractionation.Both exhibited a significant positive correlation with the total P in the water column,suggesting that internal loading may be an important source of P for the lake ecosystem.Biogenic P other than ortho-P may contribute to phytoplankton growth,with the relative proportion being 4.4%-18.7%.The release of labile P fractions fueled algal bloom,and the decay of organic matter,following the bloom events,consumed oxygen and elevated the pH value.This co-dependence might lead to a vicious cycle.Transformation mechanisms of various P species remain ambiguous and are worthy of further investigation.展开更多
The 2015/2016 El Nino event reached the threshold of super El Nino event,and was comparable to the super events in 1982/1983 and 1997/1998.Interestingly,the tropical cyclones(TCs)were found to have very late onsets in...The 2015/2016 El Nino event reached the threshold of super El Nino event,and was comparable to the super events in 1982/1983 and 1997/1998.Interestingly,the tropical cyclones(TCs)were found to have very late onsets in the decaying years of the super El Nino events.This study discusses the causes of late TC onsets related with atmospheric circulation,disturbance sources and trigger mechanisms.The analysis shows that the western North Pacific subtropical high(WNPSH)from January–June during the decaying years of the super El Nino events were stronger than the climatic mean,which resulted in a relatively stable atmospheric state by inhibiting deep convection.As a disturbance source,the April–June intertropical convergence zone(ITCZ)during the decaying years of the super El Nino events were significantly weaker than its climatic mean.The cross-equatorial flow and monsoon trough,as important TC generation triggers,were weaker from April–June during the decaying years of the super El Nino events,which further reduced the probability of TC generation.As for the late TC onsets,the role of atmospheric circulation anomalies(i.e.,subtropical-high,the ITCZ,cross-equatorial flow,and monsoon trough)were more important.The cross-equatorial flow may take as predictor of TC onsets in the decaying years of the super El Nino events.展开更多
African swine fever virus(ASFV)poses a significant threat to the global swine industry.Currently,there are no effective vaccines or treatments available to combat ASFV infection in pigs.The primary means of controllin...African swine fever virus(ASFV)poses a significant threat to the global swine industry.Currently,there are no effective vaccines or treatments available to combat ASFV infection in pigs.The primary means of controlling the spread of the disease is through rapid detection and subsequent elimination of infected pig.Recently,a lower virulent ASFV isolate with a deleted EP402R gene(CD2v-deleted)has been reported in China,which further complicates the control of ASFV infection in pig farms.Furthermore,an EP402R-deleted ASFV variant has been developed as a potential live attenuated vaccine candidate strain.Therefore,it is crucial to develop detection methods that can distinguish wild-type and EP402R-deleted ASFV infections.In this study,two recombinant ASFV-p72 and-CD2v proteins were expressed using a prokaryotic system and used to immunize Bactrian camels.Subsequently,eight nanobodies against ASFV-p72 and ten nanobodies against ASFV-CD2v were screened.Following the production of these nanobodies with horse radish peroxidase(HRP)fusion proteins,the ASFV-p72-Nb2-HRP and ASFV-CD2v-Nb22-HRP fusions were selected for the development of two competitive ELISAs(cELISAs)to detect anti-ASFV antibodies.The two cELISAs exhibited high sensitivity,good specificity,repeatability,and stability.The coincidence rate between the two cELISAs and commercial ELISA kits was 98.6%and 97.6%,respectively.Collectively,the two cELISA for detecting antibodies against ASFV demonstrated ease of operation,a low cost,and a simple production process.The two cELISAs could determine whether pigs were infected with wild-type or CD2v-deleted ASFV,and could play an important role in monitoring ASFV infections in pig farms.展开更多
The distribution characteristics of phosphorus （P） forms in the sediment profile of Lake Erhai, in southwestern China has been investigated by sequential extraction and 31p nuclear magnetic resonance spectroscopy （...The distribution characteristics of phosphorus （P） forms in the sediment profile of Lake Erhai, in southwestern China has been investigated by sequential extraction and 31p nuclear magnetic resonance spectroscopy （NMR） of NaOH extracts to understand P dynamics and its potential contribution to lake eutrophication. Contents of P fractions varied in the order of NH4C1 extracted P （NH4C1- P） 〈 bicarbonate-dithionite extracted P （BD-P） 〈 HC1-P, Residual-P 〈 NaOH extracted P （NaOH-P）. The highly available NH4C1-P represented less than 1% of total P （TP）. BD-P and NaOH extracted reactive P （NaOH-rP） averaged 39%, while the ratio of Fe/P was higher than 15, indicating low P release from the sediments under permanent oxic condition. The less bio-available HC1-P, NaOH extracted nonreactive P （NaOH-nrP） and residual-P contributed 61% of TP. Regression analysis revealed that BD-P, NaOH-rP and HC1-P were positively correlated with the contents of Fe and Mn, A1 and Fe, and Ca, respectively. The investigation of P compound groups in NaOH extracts by 31p NMR showed that ortho-P and monoester-P were the largest two constituents of the P pool, followed by diester-P, phosphonate and pyro-P. A comparison of vertical variations of P groups in the sediment profile suggested that these compounds were involved in the P recycling to different extents in Lake Erhai. In particular, the lake exhibits high potential for labile P release from the surface sediments, which should be taken into consideration even after the outsourced P runoff ceased.展开更多
Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like perfo...Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like performance.Unfortunately,these PMs suffer from limited write endurance.Existing space management strategies of PM file systems can induce a severely unbalanced wear problem,which can damage the underlying PMs quickly.In this paper,we propose a Wear-leveling-aware Multi-grained Allocator,called WMAlloc,to achieve the wear leveling of PMs while improving the performance of file systems.WMAlloc adopts multiple min-heaps to manage the unused space of PMs.Each heap represents an allocation granularity.Then,WMAlloc allocates less-worn blocks from the corresponding min-heap for allocation requests.Moreover,to avoid recursive split and inefficient heap locations in WMAlloc,we further propose a bitmap-based multi-heap tree(BMT)to enhance WMAlloc,namely,WMAlloc-BMT.We implement WMAlloc and WMAlloc-BMT in the Linux kernel based on NOVA,a typical PM file system.Experimental results show that,compared with the original NOVA and dynamic wear-aware range management(DWARM),which is the state-of-the-art wear-leveling-aware allocator of PM file systems,WMAlloc can,respectively,achieve 4.11×and 1.81×maximum write number reduction and 1.02×and 1.64×performance with four workloads on average.Furthermore,WMAlloc-BMT outperforms WMAlloc with 1.08×performance and achieves 1.17×maximum write number reduction with four workloads on average.展开更多
基金financially supported by the National Key Research and Development Project by MOST of China(No.2016YFA0601003)the National Natural Science Foundation of China(Nos.U1612441 and 41173125)Science and Technology Project of Guizhou Province
文摘In order to characterize the oxygen isotopic composition of internal phosphate and explore the possibility of using these data to identify phosphate sources, we measured oxygen isotopic compositions of phosphate(δ^(18)O_p) in sediment pore water in Hongfeng Lake, a typical deep-water lake in a mountainous area. These data, in combination with δ^(18)O_p in surface water samples and water column samples, were successfully used to identify phosphate sources. The δ^(18)O_p value of sediment pore water ranged from 15.2% to 15.8%, with an average value of 15.5%—the δ^(18)O_p value of internal phosphate. The δ^(18)O_p values decreased gradually through the water column from 19.4% in surface water to 16.4% in deeper water, implying that internal phosphate had more negative δ^(18)O_p values than external phosphate. This finding was substantiated by horizontal variations in δ^(18)O_p values, which decreased with increasing distance from inflowing rivers. All collected evidence suggests that external and internal phosphate have distinctly different isotopic signatures and that these signatures have not been considerably altered by biological mediation in Hongfeng Lake. Therefore, δ^(18)O_p can be used to distinguish phosphate sources. A two-endmember mixing model showed that internal phosphate had an average contribution of 40%, highlighting the influence of internal phosphorus loading on aqueous phosphate and eutrophication. This study illustrates the need to reduce the internal phosphorus load from sediment and provides guidance for nutrient management and in-lake restoration treatment in Hongfeng Lake. The data presented here are limited, but serve to highlight the great potential of δ^(18)O_p as an effective tracer for identifying phosphate sources. Systematic investigations of the oxygen isotopic compositions of external phosphate, internal phosphate, and phosphate through the water column, in combination with in-lake P biogeochemical cycle study, would be desirable in further research.
基金supported by the National Natural Science Foundation of China(No.41273151,41273148, 40903052)the Opening Project of Key Laboratory of Solid Waste Treatment and Resource Recycle,Ministry of Education(13zxgkO3)
文摘Phosphorus(P) species in surface sediments from a shallow,hypertrophic lake,Lake Dianchi,China,were investigated by P fractionation and ^(31)P nuclear magnetic resonance(NMR) spectroscopy during a regional algal bloom.In addition,their potential contributions to the overlying water were also evaluated.Labile fractions of P extracted by NH_4C1,bicarbonate dithionite and NaOH ranged from 340.6 to 1,725.8 mg kg^(-1),accounting for20.5%-67.2%of the total P.A two-step extraction method refinement of P recovery was performed before the^(31)P NMR analysis.Recovery rates of sedimentary TP and organic P,by combining EDTA pretreatment and NaOH or mixed reagents,ranged from 31.8%to 69.3%and from19.8%to 51.7%.^(31)P NMR results showed that ortho-P and monoester-P were the most abundant P components in the sediment extractable P of sediments,followed by diester-P and pyro-P.Spatial distribution of the sum of ortho-P,diester-P and pyro-P detected by P NMR corresponded well with the labile P concentration determined by fractionation.Both exhibited a significant positive correlation with the total P in the water column,suggesting that internal loading may be an important source of P for the lake ecosystem.Biogenic P other than ortho-P may contribute to phytoplankton growth,with the relative proportion being 4.4%-18.7%.The release of labile P fractions fueled algal bloom,and the decay of organic matter,following the bloom events,consumed oxygen and elevated the pH value.This co-dependence might lead to a vicious cycle.Transformation mechanisms of various P species remain ambiguous and are worthy of further investigation.
基金The National Key Research and Development Program for Developing Basic Sciences under contract No.2016YFC1401601the National Natural Science Foundation of China under contract No.41576026
文摘The 2015/2016 El Nino event reached the threshold of super El Nino event,and was comparable to the super events in 1982/1983 and 1997/1998.Interestingly,the tropical cyclones(TCs)were found to have very late onsets in the decaying years of the super El Nino events.This study discusses the causes of late TC onsets related with atmospheric circulation,disturbance sources and trigger mechanisms.The analysis shows that the western North Pacific subtropical high(WNPSH)from January–June during the decaying years of the super El Nino events were stronger than the climatic mean,which resulted in a relatively stable atmospheric state by inhibiting deep convection.As a disturbance source,the April–June intertropical convergence zone(ITCZ)during the decaying years of the super El Nino events were significantly weaker than its climatic mean.The cross-equatorial flow and monsoon trough,as important TC generation triggers,were weaker from April–June during the decaying years of the super El Nino events,which further reduced the probability of TC generation.As for the late TC onsets,the role of atmospheric circulation anomalies(i.e.,subtropical-high,the ITCZ,cross-equatorial flow,and monsoon trough)were more important.The cross-equatorial flow may take as predictor of TC onsets in the decaying years of the super El Nino events.
基金supported by the Natural Science Foundation of China(grant no.32273041)the Natural Science Foundation of Shaanxi Province of China(grant no.2022JC-12)+1 种基金the Key R&D Program of Shaanxi Province(grant no.S2022-YF-YBNY-0673)the Central Public-interest Scientific Institution Basal Research Fund.
文摘African swine fever virus(ASFV)poses a significant threat to the global swine industry.Currently,there are no effective vaccines or treatments available to combat ASFV infection in pigs.The primary means of controlling the spread of the disease is through rapid detection and subsequent elimination of infected pig.Recently,a lower virulent ASFV isolate with a deleted EP402R gene(CD2v-deleted)has been reported in China,which further complicates the control of ASFV infection in pig farms.Furthermore,an EP402R-deleted ASFV variant has been developed as a potential live attenuated vaccine candidate strain.Therefore,it is crucial to develop detection methods that can distinguish wild-type and EP402R-deleted ASFV infections.In this study,two recombinant ASFV-p72 and-CD2v proteins were expressed using a prokaryotic system and used to immunize Bactrian camels.Subsequently,eight nanobodies against ASFV-p72 and ten nanobodies against ASFV-CD2v were screened.Following the production of these nanobodies with horse radish peroxidase(HRP)fusion proteins,the ASFV-p72-Nb2-HRP and ASFV-CD2v-Nb22-HRP fusions were selected for the development of two competitive ELISAs(cELISAs)to detect anti-ASFV antibodies.The two cELISAs exhibited high sensitivity,good specificity,repeatability,and stability.The coincidence rate between the two cELISAs and commercial ELISA kits was 98.6%and 97.6%,respectively.Collectively,the two cELISA for detecting antibodies against ASFV demonstrated ease of operation,a low cost,and a simple production process.The two cELISAs could determine whether pigs were infected with wild-type or CD2v-deleted ASFV,and could play an important role in monitoring ASFV infections in pig farms.
基金supported by the National Natural Science Foundation of China (No. 40903052,41273151)the National Basic Research Program (973) of China (No.2008CB418006)the opening foundation of Guizhou University (No. 2009GDGP0105)
文摘The distribution characteristics of phosphorus （P） forms in the sediment profile of Lake Erhai, in southwestern China has been investigated by sequential extraction and 31p nuclear magnetic resonance spectroscopy （NMR） of NaOH extracts to understand P dynamics and its potential contribution to lake eutrophication. Contents of P fractions varied in the order of NH4C1 extracted P （NH4C1- P） 〈 bicarbonate-dithionite extracted P （BD-P） 〈 HC1-P, Residual-P 〈 NaOH extracted P （NaOH-P）. The highly available NH4C1-P represented less than 1% of total P （TP）. BD-P and NaOH extracted reactive P （NaOH-rP） averaged 39%, while the ratio of Fe/P was higher than 15, indicating low P release from the sediments under permanent oxic condition. The less bio-available HC1-P, NaOH extracted nonreactive P （NaOH-nrP） and residual-P contributed 61% of TP. Regression analysis revealed that BD-P, NaOH-rP and HC1-P were positively correlated with the contents of Fe and Mn, A1 and Fe, and Ca, respectively. The investigation of P compound groups in NaOH extracts by 31p NMR showed that ortho-P and monoester-P were the largest two constituents of the P pool, followed by diester-P, phosphonate and pyro-P. A comparison of vertical variations of P groups in the sediment profile suggested that these compounds were involved in the P recycling to different extents in Lake Erhai. In particular, the lake exhibits high potential for labile P release from the surface sediments, which should be taken into consideration even after the outsourced P runoff ceased.
基金Project supported by the National Natural Science Foundation of China(No.62162011)the Doctor Funds of Guizhou University,China(Nos.2020(13)and 2022(44))。
文摘Persistent memory(PM)file systems have been developed to achieve high performance by exploiting the advanced features of PMs,including nonvolatility,byte addressability,and dynamic random access memory(DRAM)like performance.Unfortunately,these PMs suffer from limited write endurance.Existing space management strategies of PM file systems can induce a severely unbalanced wear problem,which can damage the underlying PMs quickly.In this paper,we propose a Wear-leveling-aware Multi-grained Allocator,called WMAlloc,to achieve the wear leveling of PMs while improving the performance of file systems.WMAlloc adopts multiple min-heaps to manage the unused space of PMs.Each heap represents an allocation granularity.Then,WMAlloc allocates less-worn blocks from the corresponding min-heap for allocation requests.Moreover,to avoid recursive split and inefficient heap locations in WMAlloc,we further propose a bitmap-based multi-heap tree(BMT)to enhance WMAlloc,namely,WMAlloc-BMT.We implement WMAlloc and WMAlloc-BMT in the Linux kernel based on NOVA,a typical PM file system.Experimental results show that,compared with the original NOVA and dynamic wear-aware range management(DWARM),which is the state-of-the-art wear-leveling-aware allocator of PM file systems,WMAlloc can,respectively,achieve 4.11×and 1.81×maximum write number reduction and 1.02×and 1.64×performance with four workloads on average.Furthermore,WMAlloc-BMT outperforms WMAlloc with 1.08×performance and achieves 1.17×maximum write number reduction with four workloads on average.
