The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how ...The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how dissolved organic matter(DOM)transformation regulates the aquatic As concentrations.The present study revealed that the DOM components from the Singe Tsangpo River(STR)basin primarily consisted of protein-like components(81.30%±6.48%),with the microbially-endogenous production being a predominant source under the control of temperature and glacier-runoff recharge along the river flow path.Notably,the chemical weathering processes have significantly facilitated the enhancement of humic-like components in the river water.Besides,the groundwater DOM characteristics were predominantly influenced by the mobilization of sedimentary organic matter and the introduction of allochthonous DOM resulting from surface-water recharge.Interestingly,humic-like components facilitated As enrichment through complexation and competitive adsorption effects in both surface water and groundwater under oxidizing conditions,whichwas supported by the significant positive correlations between As and humiclike component(R^(2)=0.31/0.65,P<0.05/0.01)and the concurrent mobilization of As and humic-like components from sediment incubation experiments.Moreover,the Structural Equation Modeling analysis revealed a stronger contribution of humic-like components to the As enrichment in the groundwater compared with surface water,possibly due to the relatively strongermicrobial activity and enhanced mobilization of humic-like components in alluvial aquifers.The present study thus provided new insights into the transformation of DOM and its important role in facilitating As enrichment in the aquatic environment from alpine river basins.展开更多
The stable carbon isotope composition of cellulose(δ^(13)Ccell)in fossil wood is valuable for reconstructing past climatic and ecological changes,on seasonal to decadal timescales.However,extracting cellulose from fo...The stable carbon isotope composition of cellulose(δ^(13)Ccell)in fossil wood is valuable for reconstructing past climatic and ecological changes,on seasonal to decadal timescales.However,extracting cellulose from fossil wood is challenging,leading to a lack ofδ^(13)Ccell data over deep time;moreover,there is a debate about whether the stable carbon isotope composition of whole wood(δ^(13)Cwood)can reliably reflect past paleoclimatic or palaeoecological conditions.Here,we present an improved method for extracting cellulose from fossil wood.We initially used conventional methods to extract cellulose from a fossil wood sample a drill core from the Yuncheng Basin,near the Chinese Loess Plateau;however,we were unsuccessful.Subsequently,we successfully extracted cellulose and recovered 94%of the cellulose after modifying the conventional procedure.This involved increasing the reaction time during lignin removal,reducing the concentration of NaOH solution during hemicellulose removal,and employing multiple centrifugation steps for sample separation instead of a single step.We examined the relationship betweenδ^(13)Ccell andδ^(13)Cwood values(n=136),and the results revealed a positive correlation between them(R^(2)=0.51,P<0.001).This indicates thatδ^(13)Cwood is a dependable proxy for qualitative paleoclimatic reconstruction.However,the apparent enrichment factorεbetweenδ^(13)Ccell andδ^(13)Cwood values varied between samples,highlighting the need for caution when using records ofδ^(13)Cwood for quantitative paleoenvironmental reconstruction.展开更多
In this study,we utilized gene knockout and overexpression techniques to generate brewer's yeast strains with either a deletion or overexpression of the fatty acyl-CoA oxidase(POX1)gene.The strains studied include...In this study,we utilized gene knockout and overexpression techniques to generate brewer's yeast strains with either a deletion or overexpression of the fatty acyl-CoA oxidase(POX1)gene.The strains studied included the parental strain,the POX1 deletion strain,and the POX1 overexpression strain.These strains were exposed to iso-αacid from hops at a concentration of 300 mg/L,leading to the induction of a viable but nonculturable(VBNC)state.Our results indicated that the silencing of the POX1 gene rendered brewer's yeast cells unable to withstand the high concentration of iso-αacid stress,ultimately leading to cell death.Conversely,the overexpression of POX1 accelerated the transition of yeast cells into the VBNC state compared to the parental strain.Furthermore,we evaluated the levels of reactive oxygen species(ROS),catalase(CAT)activity,superoxide dismutase(SOD)activity,glutathione reductase(GR)activity,and the m RNA expression of genes that regulate these enzymes(the stress-inducible yeast Mpv17(SYM1)gene,CTA1,SOD1,and glutathione reductase(GLR1)gene)in brewer's yeast cells at three distinct stages:normal,short-term stress,and VBNC states.Based on these findings,it can be inferred that the formation of the VBNC state in brewer's yeast is associated with the response to oxidative stress.展开更多
Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as ...Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as they tend to be laborious,time-consuming,or technically difficult.Disinfection byproducts(DBPs)are a family of well-known secondary pollutants formed by the reactions of chemical disinfectants with DBP precursors during water disinfection treatment.Since DBP precursors have various origins(e.g.,natural,domestic,industrial,and agricultural sources),and since the formation of DBPs from different precursors in the presence of specific disinfectants is distinctive,we argue that DBPs and DBP precursors can serve as alternative indicators to assess the contamination in water sources and identify pollution origins.After providing a retrospective of the origins of DBPs and DBP precursors,as well as the specific formation patterns of DBPs from different precursors,this article presents an overview of the impacts of various natural and anthropogenic factors on DBPs and DBP precursors in drinking water sources.In practice,the DBPs(i.e.,their concentration and speciation)originally present in source water and the DBP precursors determined using DBP formation potential tests—in which water samples are dosed with a stoichiometric excess of specific disinfectants in order to maximize DBP formation under certain reaction conditions—can be considered as alternative metrics.When jointly used with other water quality parameters(e.g.,dissolved organic carbon,dissolved organic nitrogen,fluorescence,and molecular weight distribution)and specific contaminants of emerging concern(e.g.,certain pharmaceuticals and personal care products),DBPs and DBP precursors in drinking water sources can provide a more comprehensive picture of water pollution for better managing water resources and ensuring human health.展开更多
The fluid-structure interaction(FSI)in aircraft hydraulic pipeline systems is of great concern because of the damage it causes.To accurately predict the vibration characteristic of long hydraulic pipelines with curved...The fluid-structure interaction(FSI)in aircraft hydraulic pipeline systems is of great concern because of the damage it causes.To accurately predict the vibration characteristic of long hydraulic pipelines with curved segments,we studied the frequency-domain modeling and solution method for FSI in these pipeline systems.Fourteen partial differential equations(PDEs)are utilized to model the pipeline FSI,considering both frequency-dependent friction and bending-flexibility modification.To address the numerical instability encountered by the traditional transfer matrix method(TMM)in solving relatively complex pipelines,an improved TMM is proposed for solving the PDEs in the frequency domain,based on the matrix-stacking strategy and matrix representation of boundary conditions.The proposed FSI model and improved solution method are validated by numerical cases and experiments.An experimental rig of a practical hydraulic system,consisting of an aircraft engine-driven pump,a Z-shaped aero-hydraulic pipeline,and a throttle valve,was constructed for testing.The magnitude ratio of acceleration to pressure is introduced to evaluate the theoretical and experimental results,which indicate that the proposed model and solution method are effective in practical applications.The methodology presented in this paper can be used as an efficient approach for the vibrational design of aircraft hydraulic pipeline systems.展开更多
基金supported by the National Natural Science Foundation of China(No.42107094)Sichuan Science and Technology Program(No.2023NSFSC0806)the Geology Bureau project of Xinjiang Uygur Autonomous Region(Nos.XGMB202356 and XGMB202358).
文摘The geogenic enrichment of arsenic(As)extensively occurred in the riverine systems from the Qinghai-Tibetan Plateau under active geothermal discharge and chemical weathering conditions,while little is known about how dissolved organic matter(DOM)transformation regulates the aquatic As concentrations.The present study revealed that the DOM components from the Singe Tsangpo River(STR)basin primarily consisted of protein-like components(81.30%±6.48%),with the microbially-endogenous production being a predominant source under the control of temperature and glacier-runoff recharge along the river flow path.Notably,the chemical weathering processes have significantly facilitated the enhancement of humic-like components in the river water.Besides,the groundwater DOM characteristics were predominantly influenced by the mobilization of sedimentary organic matter and the introduction of allochthonous DOM resulting from surface-water recharge.Interestingly,humic-like components facilitated As enrichment through complexation and competitive adsorption effects in both surface water and groundwater under oxidizing conditions,whichwas supported by the significant positive correlations between As and humiclike component(R^(2)=0.31/0.65,P<0.05/0.01)and the concurrent mobilization of As and humic-like components from sediment incubation experiments.Moreover,the Structural Equation Modeling analysis revealed a stronger contribution of humic-like components to the As enrichment in the groundwater compared with surface water,possibly due to the relatively strongermicrobial activity and enhanced mobilization of humic-like components in alluvial aquifers.The present study thus provided new insights into the transformation of DOM and its important role in facilitating As enrichment in the aquatic environment from alpine river basins.
基金support for this research was provided by the National Natural Science Foundation of China(Grant No.42072211)the Fundamental Research Funds for the Central Universities,China(No.lzujbky-2021-ey12).
文摘The stable carbon isotope composition of cellulose(δ^(13)Ccell)in fossil wood is valuable for reconstructing past climatic and ecological changes,on seasonal to decadal timescales.However,extracting cellulose from fossil wood is challenging,leading to a lack ofδ^(13)Ccell data over deep time;moreover,there is a debate about whether the stable carbon isotope composition of whole wood(δ^(13)Cwood)can reliably reflect past paleoclimatic or palaeoecological conditions.Here,we present an improved method for extracting cellulose from fossil wood.We initially used conventional methods to extract cellulose from a fossil wood sample a drill core from the Yuncheng Basin,near the Chinese Loess Plateau;however,we were unsuccessful.Subsequently,we successfully extracted cellulose and recovered 94%of the cellulose after modifying the conventional procedure.This involved increasing the reaction time during lignin removal,reducing the concentration of NaOH solution during hemicellulose removal,and employing multiple centrifugation steps for sample separation instead of a single step.We examined the relationship betweenδ^(13)Ccell andδ^(13)Cwood values(n=136),and the results revealed a positive correlation between them(R^(2)=0.51,P<0.001).This indicates thatδ^(13)Cwood is a dependable proxy for qualitative paleoclimatic reconstruction.However,the apparent enrichment factorεbetweenδ^(13)Ccell andδ^(13)Cwood values varied between samples,highlighting the need for caution when using records ofδ^(13)Cwood for quantitative paleoenvironmental reconstruction.
基金funded by National Natural Science Foundation of China(32272279)the Key R&D project of Shandong Province(2023CXPT007)the Key R&D project of Qingdao Science and Technology Plan(22-3-3-hygg-29-hy)。
文摘In this study,we utilized gene knockout and overexpression techniques to generate brewer's yeast strains with either a deletion or overexpression of the fatty acyl-CoA oxidase(POX1)gene.The strains studied included the parental strain,the POX1 deletion strain,and the POX1 overexpression strain.These strains were exposed to iso-αacid from hops at a concentration of 300 mg/L,leading to the induction of a viable but nonculturable(VBNC)state.Our results indicated that the silencing of the POX1 gene rendered brewer's yeast cells unable to withstand the high concentration of iso-αacid stress,ultimately leading to cell death.Conversely,the overexpression of POX1 accelerated the transition of yeast cells into the VBNC state compared to the parental strain.Furthermore,we evaluated the levels of reactive oxygen species(ROS),catalase(CAT)activity,superoxide dismutase(SOD)activity,glutathione reductase(GR)activity,and the m RNA expression of genes that regulate these enzymes(the stress-inducible yeast Mpv17(SYM1)gene,CTA1,SOD1,and glutathione reductase(GLR1)gene)in brewer's yeast cells at three distinct stages:normal,short-term stress,and VBNC states.Based on these findings,it can be inferred that the formation of the VBNC state in brewer's yeast is associated with the response to oxidative stress.
基金supported by the National Natural Science Foundation of China(52325001,52170009,and 52091542)the National Key Research and Development Program of China(2021YFC3200700)+3 种基金the Program of Shanghai Academic Research Leader,China(21XD1424000)the International Cooperation Project of Shanghai Science and Technology Commission(20230714100)the Key-Area Research and Development Program of Guangdong Province(2020B1111350001)Tongji University Youth 100 Program.
文摘Tracing the contamination origins in water sources and identifying the impacts of natural and human processes are essential for ecological safety and public health.However,current analysis approaches are not ideal,as they tend to be laborious,time-consuming,or technically difficult.Disinfection byproducts(DBPs)are a family of well-known secondary pollutants formed by the reactions of chemical disinfectants with DBP precursors during water disinfection treatment.Since DBP precursors have various origins(e.g.,natural,domestic,industrial,and agricultural sources),and since the formation of DBPs from different precursors in the presence of specific disinfectants is distinctive,we argue that DBPs and DBP precursors can serve as alternative indicators to assess the contamination in water sources and identify pollution origins.After providing a retrospective of the origins of DBPs and DBP precursors,as well as the specific formation patterns of DBPs from different precursors,this article presents an overview of the impacts of various natural and anthropogenic factors on DBPs and DBP precursors in drinking water sources.In practice,the DBPs(i.e.,their concentration and speciation)originally present in source water and the DBP precursors determined using DBP formation potential tests—in which water samples are dosed with a stoichiometric excess of specific disinfectants in order to maximize DBP formation under certain reaction conditions—can be considered as alternative metrics.When jointly used with other water quality parameters(e.g.,dissolved organic carbon,dissolved organic nitrogen,fluorescence,and molecular weight distribution)and specific contaminants of emerging concern(e.g.,certain pharmaceuticals and personal care products),DBPs and DBP precursors in drinking water sources can provide a more comprehensive picture of water pollution for better managing water resources and ensuring human health.
基金supported by the National Natural Science Foundation of China(Nos.51975025 and 51890822)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2016QNRC001)the National Key Research and Development Program of China(No.2019YFB2004500)。
文摘The fluid-structure interaction(FSI)in aircraft hydraulic pipeline systems is of great concern because of the damage it causes.To accurately predict the vibration characteristic of long hydraulic pipelines with curved segments,we studied the frequency-domain modeling and solution method for FSI in these pipeline systems.Fourteen partial differential equations(PDEs)are utilized to model the pipeline FSI,considering both frequency-dependent friction and bending-flexibility modification.To address the numerical instability encountered by the traditional transfer matrix method(TMM)in solving relatively complex pipelines,an improved TMM is proposed for solving the PDEs in the frequency domain,based on the matrix-stacking strategy and matrix representation of boundary conditions.The proposed FSI model and improved solution method are validated by numerical cases and experiments.An experimental rig of a practical hydraulic system,consisting of an aircraft engine-driven pump,a Z-shaped aero-hydraulic pipeline,and a throttle valve,was constructed for testing.The magnitude ratio of acceleration to pressure is introduced to evaluate the theoretical and experimental results,which indicate that the proposed model and solution method are effective in practical applications.The methodology presented in this paper can be used as an efficient approach for the vibrational design of aircraft hydraulic pipeline systems.
