Film hole irrigation has been widely adopted as an effective water-saving irrigation technology in the arid and semiarid areas of China.To investigate the effects of initial soil moisture content(θ0)on soil water and...Film hole irrigation has been widely adopted as an effective water-saving irrigation technology in the arid and semiarid areas of China.To investigate the effects of initial soil moisture content(θ0)on soil water and nitrogen transport characteristics under muddy water film hole infiltration,the laboratory experiments were conducted with muddy water film hole infiltration,using five initial soil moisture content treatments.The models for describing the relationships between the cumulative infiltration(I(t))and infiltration duration(t);the relationship among the horizontal and vertical migration distances of the wetting front(Fx,Fz),θ0 and t,were established.The results showed that the initial soil moisture content had a significant effect on I(t),Fx,Fz and moisture content distribution in the wetted body.The change of I(t)over t conformed to Kostiakov model.With the increase ofθ0,the infiltration coefficient(K)gradually decreased.NO-3-N was mainly distributed in the range of the wetting radius of 15 cm,while NH+4-N was mainly distributed in the range of the wetting radius of 8 cm.This study can provide a theoretical basis and technical support for film hole irrigation.展开更多
To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,and pH were measured under different operating conditions.The flocs were obtained from a laborato...To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,and pH were measured under different operating conditions.The flocs were obtained from a laboratory-scale sequencing batch reactor.Nitrification,as observed from interfacial ammonium and nitrate fluxes,was higher at pH 8.5,than at pH 6.5 and 7.5.At pH 8.5,heterotrophic bacteria used less oxygen than nitrifying bacteria,whereas at lower pH heterotrophic activity dominated.When the ratio of C to N was decreased from 20 to 10,the ammonium uptake increased.When dissolved oxygen(DO)concentration in the bulk liquid was decreased from 4 to 2 mg·L^(-1),nitrification decreased,and only 25%of the DO influx into the flocs was used for nitrification.This study indicated that nitrifying bacteria became more competitive at a higher DO concentration,a higher pH value(approximately 8.5)and a lower C/N.展开更多
In recent years,in order to improve nutrient use efficiency,especially nitrogen use efficiency,fertilizer valueadded technology has been developed rapidly.However,the mechanism of the effect of synergistic fertilizer ...In recent years,in order to improve nutrient use efficiency,especially nitrogen use efficiency,fertilizer valueadded technology has been developed rapidly.However,the mechanism of the effect of synergistic fertilizer on plant nitrogen utilization is not clear.A study was,therefore,conducted to explore the activities and gene expression of key enzymes for nitrogen assimilation and the gene expression of nitrogen transporters in wheat after the application of synergistic fertilizer.Soil column experiment was set up in Qingdao Agricultural University experimental base from October 2018 to June 2019.Maleic acid and itaconic acid were copolymerized with acrylic acid as cross-linking monomer to make a fluid gel,which was sprayed on the fertilizer surface to make nitrogen and phosphorus synergistic fertilizer.A total of 6 treatments was set according to different nitrogen and phosphorus fertilizer ratios:(1)100%common nitrogen fertilizer+100%common phosphate fertilizer(2)70%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(3)100%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(4)100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(5)70%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(6)100%commercial nitrogen synergistic fertilizer+100%commercial phosphorus synergistic fertilizer.The results are as follows:(1)the enzyme activities of wheat plants under synergistic fertilizer condition were higher than those under ordinary fertilizer,except under the treatment that nitrogen and phosphorus synergistic fertilizer were both reduced;(2)the expression level of the genes under the treatment“100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer”was significantly higher than those in other treatments.Combined with the higher performance of nitrogen concentration in various parts of the plant under the condition of applying synergistic fertilizer,this study indicated that the application of synergistic fertilizer can improve the nitrogen metabolism of the plant by increasing the nitrogen level in the rhizosphere soil,inducing the expression of nitrogen transporter genes and key assimilation enzymes genes.展开更多
As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which i...As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces(passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential(Eh) and p H, and microorganisms are the predominant pulling forces(active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.展开更多
Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in ...Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in the red seaweed Pyropia yezoensis causes senescence-like discoloration. In this study, we identified five genes in P. yezoensis encoding AMT domain-containing proteins, which were phylogenetically categorized into the AMT1 subfamily. We also found a gene encoding a Rhesus protein (Rh) that was related to, but diverged from, AMTs. Moreover, our phylogenetic analysis showed that AMT domain-containing proteins from micro- and macro-algae belonged to either the AMT1 or Rh subfamily, indicating the absence of AMT2 in algae. Gene expression analyses revealed the presence of gametophyte- and sporophyte-specific AMT1 genes that were up-regulated transiently and continually, respectively, under nitrogen-deficient conditions. In addition, up-regulated sporophyte-specific gene expression was suppressed when nitrogen was resupplied. Accordingly, an expansion of the ancient AMT gene has produced AMT1 functional variants differing in temporal and nitrogen starvation-inducible expression patterns during the life cycle of P. yezoensis. These findings help elucidate the unique nutrition starvation responses involving functionally diverse AMT1 and Rh subfamilies in red seaweed.展开更多
We investigate the electronic transport properties of dipyrimidinyl-diphenyl sandwiched between two armchair graphene nanoribbon electrodes using the nonequilibrium Green function formalism combined with a first-princ...We investigate the electronic transport properties of dipyrimidinyl-diphenyl sandwiched between two armchair graphene nanoribbon electrodes using the nonequilibrium Green function formalism combined with a first-principles method based on density functional theory. Among the three models M1–M3, M1 is not doped with a heteroatom. In the left parts of M2 and M3, nitrogen atoms are doped at two edges of the nanoribbon. In the right parts, nitrogen atoms are doped at one center and at the edges of M2 and M3, respectively. Comparisons of M1, M2 and M3 show obvious rectifying characteristics, and the maximum rectification ratios are up to 42.9 in M2. The results show that the rectifying behavior is strongly dependent on the doping position of electrodes. A higher rectification ratio can be found in the dipyrimidinyl-diphenyl molecular device with asymmetric doping of left and right electrodes, which suggests that this system has a broader application in future logic and memory devices.展开更多
基金This work was jointly supported by the National Natural Science Foundation of China projects[grant numbers 42305178 and U2344224]the National Key Scientific and Technological Infrastructure project“Earth System Numerical Simulation Facility”(EarthLab).
基金This study was financially supported by the National Key Research and Development Program of China(Grant No.2016YFC0400204)the National Natural Science Foundation of China(Grant No.52079105,51779205 and 51479161)+1 种基金and the Public welfare industry research special project(Grant No.201203003)The authors acknowledge the anonymous reviewers and the editor for their valuable comments and suggestions.
文摘Film hole irrigation has been widely adopted as an effective water-saving irrigation technology in the arid and semiarid areas of China.To investigate the effects of initial soil moisture content(θ0)on soil water and nitrogen transport characteristics under muddy water film hole infiltration,the laboratory experiments were conducted with muddy water film hole infiltration,using five initial soil moisture content treatments.The models for describing the relationships between the cumulative infiltration(I(t))and infiltration duration(t);the relationship among the horizontal and vertical migration distances of the wetting front(Fx,Fz),θ0 and t,were established.The results showed that the initial soil moisture content had a significant effect on I(t),Fx,Fz and moisture content distribution in the wetted body.The change of I(t)over t conformed to Kostiakov model.With the increase ofθ0,the infiltration coefficient(K)gradually decreased.NO-3-N was mainly distributed in the range of the wetting radius of 15 cm,while NH+4-N was mainly distributed in the range of the wetting radius of 8 cm.This study can provide a theoretical basis and technical support for film hole irrigation.
基金This work was supported by Program for Changjiang Scholars and Innovative Research Team in University(No.IRT0853)State Commission of Science Technology of China(No.2009ZX07212-002)+1 种基金State Key Laboratory of Western Architecture and Technology(No.10KF08)Foundation of Shaanxi Educational Committee(No.11JK0759).
文摘To investigate the nitrogen transport and conversion inside activated sludge flocs,micro-profiles of O2,NHt 4,NO-2,NO-3,and pH were measured under different operating conditions.The flocs were obtained from a laboratory-scale sequencing batch reactor.Nitrification,as observed from interfacial ammonium and nitrate fluxes,was higher at pH 8.5,than at pH 6.5 and 7.5.At pH 8.5,heterotrophic bacteria used less oxygen than nitrifying bacteria,whereas at lower pH heterotrophic activity dominated.When the ratio of C to N was decreased from 20 to 10,the ammonium uptake increased.When dissolved oxygen(DO)concentration in the bulk liquid was decreased from 4 to 2 mg·L^(-1),nitrification decreased,and only 25%of the DO influx into the flocs was used for nitrification.This study indicated that nitrifying bacteria became more competitive at a higher DO concentration,a higher pH value(approximately 8.5)and a lower C/N.
基金supported by the Program of Shandong Modern Agricultural Technology and Industry System–Cultivation and Soil Fertilizer(SDAIT0107)the Major Application Technology Innovation Projects in Shandong Province and the Key Research and Development Projects of Shandong Province.
文摘In recent years,in order to improve nutrient use efficiency,especially nitrogen use efficiency,fertilizer valueadded technology has been developed rapidly.However,the mechanism of the effect of synergistic fertilizer on plant nitrogen utilization is not clear.A study was,therefore,conducted to explore the activities and gene expression of key enzymes for nitrogen assimilation and the gene expression of nitrogen transporters in wheat after the application of synergistic fertilizer.Soil column experiment was set up in Qingdao Agricultural University experimental base from October 2018 to June 2019.Maleic acid and itaconic acid were copolymerized with acrylic acid as cross-linking monomer to make a fluid gel,which was sprayed on the fertilizer surface to make nitrogen and phosphorus synergistic fertilizer.A total of 6 treatments was set according to different nitrogen and phosphorus fertilizer ratios:(1)100%common nitrogen fertilizer+100%common phosphate fertilizer(2)70%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(3)100%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(4)100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer;(5)70%nitrogen synergistic fertilizer+70%phosphorus synergistic fertilizer;(6)100%commercial nitrogen synergistic fertilizer+100%commercial phosphorus synergistic fertilizer.The results are as follows:(1)the enzyme activities of wheat plants under synergistic fertilizer condition were higher than those under ordinary fertilizer,except under the treatment that nitrogen and phosphorus synergistic fertilizer were both reduced;(2)the expression level of the genes under the treatment“100%nitrogen synergistic fertilizer+100%phosphorus synergistic fertilizer”was significantly higher than those in other treatments.Combined with the higher performance of nitrogen concentration in various parts of the plant under the condition of applying synergistic fertilizer,this study indicated that the application of synergistic fertilizer can improve the nitrogen metabolism of the plant by increasing the nitrogen level in the rhizosphere soil,inducing the expression of nitrogen transporter genes and key assimilation enzymes genes.
基金the National Natural Science Foundation of China (Grant No. 41272249)Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110072110020)
文摘As an essential component of proteins and genetic material for all organisms, nitrogen(N) is one of the major limiting factors that control the dynamics, biodiversity and functioning of lacustrine wetlands, in which intensified N biogeochemical activities take place. Reactive N loaded into wetland ecosystems has been doubled due to various human activities, including industrial, agricultural activities and urbanization. The main driving mechanisms of N transport and transformation in lacustrine wetlands are categorized to pushing forces and pulling forces in this study. Geomorphology, wetland age, N concentrations, and temperature are the main pushing forces(passive forces); whereas water table variation, oxygen concentration, other elements availability, oxidation-reduction potential(Eh) and p H, and microorganisms are the predominant pulling forces(active forces). The direction and kinetic energy of reactions are determined by pulling forces and then are stimulated by pushing forces. These two types of forces are analyzed and discussed separately. Based on the analysis of driving mechanisms, possible solutions to wetland N pollutions are proposed at individual, regional and global scales, respectively. Additional research needs are addressed to obtain a thorough understanding of N transport and transformations in wetlands and to reduce detrimental impacts of excessive N on such fragile ecosystems.
文摘Nitrogen deficiency induces senescence and the expression of genes encoding ammonium transporters (AMTs) in terrestrial plants where the AMT family is subdivided into AMT1 and AMT2 subfamilies. Nitrogen starvation in the red seaweed Pyropia yezoensis causes senescence-like discoloration. In this study, we identified five genes in P. yezoensis encoding AMT domain-containing proteins, which were phylogenetically categorized into the AMT1 subfamily. We also found a gene encoding a Rhesus protein (Rh) that was related to, but diverged from, AMTs. Moreover, our phylogenetic analysis showed that AMT domain-containing proteins from micro- and macro-algae belonged to either the AMT1 or Rh subfamily, indicating the absence of AMT2 in algae. Gene expression analyses revealed the presence of gametophyte- and sporophyte-specific AMT1 genes that were up-regulated transiently and continually, respectively, under nitrogen-deficient conditions. In addition, up-regulated sporophyte-specific gene expression was suppressed when nitrogen was resupplied. Accordingly, an expansion of the ancient AMT gene has produced AMT1 functional variants differing in temporal and nitrogen starvation-inducible expression patterns during the life cycle of P. yezoensis. These findings help elucidate the unique nutrition starvation responses involving functionally diverse AMT1 and Rh subfamilies in red seaweed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11504283 and 21503153the Natural Science Foundation of Shaanxi Province under Grant No 2014JM1025the Science and Technology Star Project of Shaanxi Province under Grant No 2016KJXX-45
文摘We investigate the electronic transport properties of dipyrimidinyl-diphenyl sandwiched between two armchair graphene nanoribbon electrodes using the nonequilibrium Green function formalism combined with a first-principles method based on density functional theory. Among the three models M1–M3, M1 is not doped with a heteroatom. In the left parts of M2 and M3, nitrogen atoms are doped at two edges of the nanoribbon. In the right parts, nitrogen atoms are doped at one center and at the edges of M2 and M3, respectively. Comparisons of M1, M2 and M3 show obvious rectifying characteristics, and the maximum rectification ratios are up to 42.9 in M2. The results show that the rectifying behavior is strongly dependent on the doping position of electrodes. A higher rectification ratio can be found in the dipyrimidinyl-diphenyl molecular device with asymmetric doping of left and right electrodes, which suggests that this system has a broader application in future logic and memory devices.
