In this work,Ag/Bi_(5)O_(7)I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange(MO)degradation.Bi_(5)O_(7)I was synthesized via a hydrothermal-calcination m...In this work,Ag/Bi_(5)O_(7)I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange(MO)degradation.Bi_(5)O_(7)I was synthesized via a hydrothermal-calcination method and shows nanorods morphology.Ag nanoparticles(NPs)were photo deposited on the Bi_(5)O_(7)I nanorods as electron trappers to improve the spatial separation of charge carriers,which was confirmed via XPS,TEM,and electronic chemical analyses.The catalytic test indicates that Bi_(5)O_(7)I presents the piezoelectric-like behavior,while the loading of Ag NPs can strengthen the character.Under ultrasonic vibration,the optimal Ag/Bi_(5)O_(7)I presents high efficiency in MO degradation.The degradation rate is determined to be 0.033 min1,which is 4.7 folds faster than that of Bi_(5)O_(7)I.The Ag/Bi_(5)O_(7)I also presents a high performance in piezocatalytic N2 fixation.The piezocatalytic NH3 generation rate reaches 65.4 μmol L^(-1)g^(-1)h^(-1)with water as a hole scavenger.The addition of methanol can hasten the piezoelectric catalytic reaction.Interestingly,when ultrasonic vibration and light irradiation simultaneously act on the Ag/Bi_(5)O_(7)I catalyst,higher performance in NH3 generation and MO degradation is observed.However,due to the weak adhesion of Ag NPs,some Ag NPs would fall off from the Bi_(5)O_(7)I surface under long-term ultrasonic vibration,which would greatly reduce the piezoelectric catalytic performance.This result indicates that a strong binding force is required when preparing the piezoelectric composite catalyst.The current work provides new insights for the development of highly efficient catalysts that can use multiple energies.展开更多
In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120&...In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N2 fixation activity and diazotroph community structure showed the dominance of unicellular N2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N2 fixation.In surface waters, volumetric N2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with <10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N2 fixation rate over the upper 200 m ranged between 150 μmol/(m^2·d)and 480 μmol/(m^2·d)average(225±105) μmol/(m^2·d). N2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.展开更多
Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixa...Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.展开更多
Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the na...Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the natural process of legume biological nitrogen fixation. However, the optimal level of N fertilization for grass-legume mixtures, to obtain the highest yield, quality, and contribution of N2 fixation, varies with species. A greenhouse pot experiment was conducted to study the temporal dynamics of N2 fixation of alfalfa （Medicago sativa L.） grown alone and in mixture with smooth bromegrass （Bromus inermis Leyss.） in response to the addition of fertilizer N. Three levels of N （0, 75, and 150 kg ha-1） were examined using 15N-labeled urea to evaluate N2 fixation via the 15N isotope dilution method. Treatments were designated NO （0.001 g per pot）, N75 （1.07 g per pot） and N150 （2.14 g per pot）. Alfalfa grown alone did not benefit from the addition of fertilizer N; dry matter was not significantly increased. In contrast, dry weight and N content of smooth bromegrass grown alone was increased significantly by N application. When grown as a mixture, smooth bromegrass biomass was increased significantly by N application, resulted in a decrease in alfalfa biomass. In addition, individual alfalfa plant dry weight （shoots＋roots） was significantly lower in the mixture than when grown alone at all N levels. Smooth bromegrass shoot and root dry weight were significantly higher when grown with alfalfa than when grown alone, regardless of N application level. When grown alone, alfalfa＇s N2 fixation was reduced with N fertilization （R2=0.9376,P=0.0057）. When grown in a mixture with smooth bromegrass, with 75 kg ha-1 of N fertilizer, the percentage of atmospheric N2 fixation contribution to total N in alfalfa （%Ndfa） had a maximum of 84.07 and 83.05% in the 2nd and 3rd harvests, respectively. Total 3-harvest %Ndfa was higher when alfalfa was grown in a mixture than when grown alone （shoots： ｜t｜=3.39, P=0.0096; root： ｜t｜=3.57, P=0.0073）. We believe this was due to smooth bromegrass being better able to absorb available soil N （due to its fibrous root system）, resulting inlower soil N availability and allowing alfalfa to develop an effective N2 fixing symbiosis prior to the 1st harvest. Once soil N levels were depleted, alfalfa was able to fix N2, resulting in the majority of its tissue N being derived from biological nitrogen fixation （BNF） in the 2nd and 3rd harvests. When grown in a mixture, with added N, alfalfa established an effective symbiosis earlier than when grown alone; in monoculture BNF did not contribute a significant portion of plant N in the N75 and N150 treatments, whereas in the mixture, BNF contributed 17.90 and 16.28% for these treatments respectively. Alfalfa has a higher BNF efficiency when grown in a mixture, initiating BNF earlier, and having higher N2 fixation due to less inhibition by soil-available N. For the greatest N-use-efficiency and sustainable production, grass-legume mixtures are recommended for imDrovino orasslands, usino a moderate amount of N fertilizer （75 kq N ha-l） to provide optimum benefits.展开更多
Legume plants are an essential component of sustainable farming systems.Phosphorus(P) deficiency is a significant constraint for legume production, especially in nutrient-poor soils of arid and semi-arid regions.In th...Legume plants are an essential component of sustainable farming systems.Phosphorus(P) deficiency is a significant constraint for legume production, especially in nutrient-poor soils of arid and semi-arid regions.In the present study, we conducted a pot experiment to evaluate the effects of a phosphorus-mobilizing plant-growth promoting rhizobacterial strain Bacillus cereus GS6, either alone or combined with phosphate-enriched compost(PEC) on the symbiotic(nodulation-N_2 fixation) performance of soybean(Glycine max(L.) Merr.) on an Aridisol.The PEC was produced by composting food waste with addition of single super phosphate.The bacterial strain B.cereus GS6 showed considerable potential for P solubilization and mobilization by releasing carboxylates in insoluble P(rock phosphate)-enriched medium.Inoculation of B.cereus GS6 in combination with PEC application significantly improved nodulation and nodule N_2 fixation efficiency.Compared to the control(without B.cereus GS6 and PEC), the combined application of B.cereus GS6 with PEC resulted in significantly higher accumulation of nitrogen(N), P, and potassium(K) in grain, shoot, and nodule.The N:P and P:K ratios in nodules were significantly altered by the application of PEC and B.cereus GS6, which reflected the important roles of P and K in symbiotic performance of soybean.The combined application of PEC and B.cereus GS6 also significantly increased the soil dehydrogenase and phosphomonoesterase activities, as well as the soil available N, P, and K contents.Significant positive relationships were found between soil organic carbon(C) content, dehydrogenase and phosphomonoesterase activities, and available N, P, and K contents.This study suggests that inoculation of P-mobilizing rhizobacteria, such as B.cereus GS6, in combination with PEC application might enhance legume productivity by improving nodulation and nodule N_2 fixation efficiency.展开更多
Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the...Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the modified F/2 medium for cultivation of marine algae. The optimal cultivation condition for exopolysaccharide yield by this cyanobacterial strain was 29℃, aeration, and continuous illumination at 86.0 μE/M^2/S. Under the optimal conditions, over 18.4 g/L of exopolysaccharide was produced within 12 days. This was so far the highest exopolysaccharide yield produced with strains of Cyanothece sp. obtained.展开更多
This study aimed to prepare and apply a novel Pt/CdMoO_(4) composite photocatalyst for photocatalytic N2 fixation and tetracycline degradation. The Pt/CdMoO_(4) composite was subjected to comprehensive investigation o...This study aimed to prepare and apply a novel Pt/CdMoO_(4) composite photocatalyst for photocatalytic N2 fixation and tetracycline degradation. The Pt/CdMoO_(4) composite was subjected to comprehensive investigation on the morphology, structure, optical properties, and photoelectric chemical properties. The results demonstrate the dispersion of Pt nanoparticles on the CdMoO_(4) surface. Close contact between CdMoO_(4) and Pt was observed, resulting in the formation of a heterojunction structure at their contact region. Density functional theory calculation and Mott-Schottky analysis revealed that Pt possesses a higher work function value than CdMoO_(4), resulting in electron drift from CdMoO_(4) to Pt and the formation of a Schottky barrier. The presence of this barrier increases the separation efficiency of electron-hole pairs, thereby improving the performance of the Pt/CdMoO_(4) composite in photocatalysis. When exposed to simulated sunlight, the optimal Pt/CdMoO_(4) catalyst displayed a photocatalytic nitrogen fixation rate of 443.7 μmol·L‒^(1)·g‒^(1)·h‒^(1), which is 3.2 times higher than that of pure CdMoO_(4). In addition, the composite also exhibited excellent performance in tetracycline degradation, with hole and superoxide species identified as the primary reactive species. These findings offer practical insights into designing and synthesizing efficient photocatalysts for photocatalytic nitrogen fixation and antibiotics removal.展开更多
With the fast-pace digitalization evolution in the current generation’s lifestyle and the industry revolution,the energy demand has been skyrocketed.Recently,the two-dimensional(2D)bismuth-based nanomaterials emerged...With the fast-pace digitalization evolution in the current generation’s lifestyle and the industry revolution,the energy demand has been skyrocketed.Recently,the two-dimensional(2D)bismuth-based nanomaterials emerged as a promising photocatalyst candidate in solar fuel conversion,not only for its exceptional light absorption capability and tunable optical properties,but it also can be synthesized into diverse variety of nanomaterials with different ranges of potential gap and band position to fulfill the potential requirement of wide range of photocatalytic reaction.Yet,the weak light harvesting ability and ultrafast charge recombination has restricted its potential in commercial application.Thus,recent researches have been focusing on tackling these issues by incorporating some modification strategies such as heteroatom doping,vacancy engineering,facet engineering,bismuth rich strategy and heterojunction engineering.Herein,this review article presents the state-of-the-art modifications on 2D bismuth-based parent material,specifically on the relationship between each of the modification strategy on the electronic properties and surface chemistry in achieving boosted photocatalytic performance.In the view of the unique charge interaction between two semiconductors with different dimensions,we systematically discuss the rational heterostructure design from the dimensionality perspective,namely,point-to-face,line-to-face,face-to-face,and bulk-to-face in solar fuel conversion to provide inspiring insights for future interface engineering.Finally,the challenges and the future research outlook in the solar-to-fuel conversion are highlighted to push forward the design of high-performance bismuth-based photocatalyst in realizing commercialscale solar-to-fuel conversion.展开更多
Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their product...Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their production rate and titer under photoautotrophic conditions are 10 to 100 folds lower than those in fast growing E. colt. Cyanobacterial factories face three indomitable bottlenecks. First, photosynthesis has limited ATP and NADPH generation rates. Second, CO2 fixation by ribulose-l,5-bisphosphate carboxylase/oxygenase （RuBisCO） has poor efficiency. Third, CO2 mass transfer and light supply are deficient within large photobioreac- tors. On the other hand, cyanobacteria may employ organic substrates to promote phototrophic cell growth, Nz fixation, and metabolite synthesis. The photo-fermenta- tions show enhanced photosynthesis, while CO2 loss from organic substrate degradation can be reused by the Calvin cycle. In addition, the plasticity of cyanobacterial path- ways （e.g., oxidative pentose phosphate pathway and the TCA cycle） has been recently revealed to facilitate the catabolism. The use of cyanobacteria as ＂green E. colt＂ could be a promising route to develop robust photobiorefineries.展开更多
基金supported by Nature Science Foundation of Zhejiang Province(Grant No.LY20B030004).
文摘In this work,Ag/Bi_(5)O_(7)I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange(MO)degradation.Bi_(5)O_(7)I was synthesized via a hydrothermal-calcination method and shows nanorods morphology.Ag nanoparticles(NPs)were photo deposited on the Bi_(5)O_(7)I nanorods as electron trappers to improve the spatial separation of charge carriers,which was confirmed via XPS,TEM,and electronic chemical analyses.The catalytic test indicates that Bi_(5)O_(7)I presents the piezoelectric-like behavior,while the loading of Ag NPs can strengthen the character.Under ultrasonic vibration,the optimal Ag/Bi_(5)O_(7)I presents high efficiency in MO degradation.The degradation rate is determined to be 0.033 min1,which is 4.7 folds faster than that of Bi_(5)O_(7)I.The Ag/Bi_(5)O_(7)I also presents a high performance in piezocatalytic N2 fixation.The piezocatalytic NH3 generation rate reaches 65.4 μmol L^(-1)g^(-1)h^(-1)with water as a hole scavenger.The addition of methanol can hasten the piezoelectric catalytic reaction.Interestingly,when ultrasonic vibration and light irradiation simultaneously act on the Ag/Bi_(5)O_(7)I catalyst,higher performance in NH3 generation and MO degradation is observed.However,due to the weak adhesion of Ag NPs,some Ag NPs would fall off from the Bi_(5)O_(7)I surface under long-term ultrasonic vibration,which would greatly reduce the piezoelectric catalytic performance.This result indicates that a strong binding force is required when preparing the piezoelectric composite catalyst.The current work provides new insights for the development of highly efficient catalysts that can use multiple energies.
基金The National Basic Research Program of China under contract No.2015CB452903the Foundation of China Ocean Mineral Resources R&D Association under contract No.DY135-E2-2-03+1 种基金the Science and Technology Basic Resources Investigation Program of China under contract No.2017FY201403the National Natural Science Foundation of China under contract Nos 41676174,41206104 and 41876198
文摘In the present study, we report N2 fixation rate(15N isotope tracer assay) and the diazotroph community structure(using the molecular method) in the western tropical North Pacific Ocean(WTNP)(13°–20°N, 120°–160°E). Our independent evidence on the basis of both in situ N2 fixation activity and diazotroph community structure showed the dominance of unicellular N2 fixation over majority of the WTNP surface waters during the sampling periods.Moreover, a shift in the diazotrophic composition from unicellular cyanobacteria group B-dominated to Trichodesmium spp.-dominated toward the western boundary current(Kuroshio) was also observed in 2013. We hypothesize that nutrient availability may have played a major role in regulating the biogeography of N2 fixation.In surface waters, volumetric N2 fixation rate(calculated by nitrogen) ranged between 0.6 and 2.6 nmol/(L·d) and averaged(1.2±0.5) nmol/(L·d), with <10 μm size fraction contributed predominantly(88%±6%) to the total rate between 135°E and 160°E. Depth-integrated N2 fixation rate over the upper 200 m ranged between 150 μmol/(m^2·d)and 480 μmol/(m^2·d)average(225±105) μmol/(m^2·d). N2 fixation can account for 6.2%±3.7% of the depthintegrated primary production, suggesting that N2 fixation is a significant N source sustaining new and export production in the WTNP. The role of N2 fixation in biogeochemical cycling in this climate change-vulnerable region calls for further investigations.
基金The National Natural Science Foundation of China under contract Nos 42076042 and 41721005the Fund of Ministry of Science and Technology of China under contract No.2017FY201403the Fund of China Ocean Mineral Resources R&D Association under contract No.DY135-13-E2-03.
文摘Nitrogen fixation is one of the most important sources of new nitrogen in the ocean and thus profoundly affects the nitrogen and carbon biogeochemical processes.The distribution,controlling factors,and flux of N2 fixation in the global ocean remain uncertain,partly because of the lack of methodological uniformity.The^(15)N_(2)tracer assay(the original bubble method→the^(15)N_(2)-enriched seawater method→the modified bubble method)is the mainstream method for field measurements of N2 fixation rates(NFRs),among which the original bubble method is the most frequently used.However,accumulating evidence has suggested an underestimation of NFRs when using this method.To improve the availability of previous data,we compared NFRs measured by three^(15)N_(2)tracer assays in the South China Sea.Our results indicate that the relationship between NFRs measured by the original bubble method and the^(15)N_(2)-enriched seawater method varies obviously with area and season,which may be influenced by incubation time,diazotrophic composition,and environmental factors.In comparison,the relationship between NFRs measured by the original bubble method and the modified bubble method is more stable,indicating that the N2 fixation rates based on the original bubble methods may be underestimated by approximately 50%.Based on this result,we revised the flux of N2 fixation in the South China Sea to 40 mmol/(m2·a).Our results improve the availability and comparability of literature NFR data in the South China Sea.The comparison of the^(15)N_(2)tracer assay for NFRs measurements on a larger scale is urgently necessary over the global ocean for a more robust understanding of the role of N2 fixation in the marine nitrogen cycle.
基金supported by the China Forage and Grass Research System (CARS-35)the National Key Technology R&D Program of China (2011BAD17B01)
文摘Planting grass and legume mixtures on improved grasslands has the potential advantage of realizing both higher yields and lower environmental pollution by optimizing the balance between applied N fertilizer and the natural process of legume biological nitrogen fixation. However, the optimal level of N fertilization for grass-legume mixtures, to obtain the highest yield, quality, and contribution of N2 fixation, varies with species. A greenhouse pot experiment was conducted to study the temporal dynamics of N2 fixation of alfalfa （Medicago sativa L.） grown alone and in mixture with smooth bromegrass （Bromus inermis Leyss.） in response to the addition of fertilizer N. Three levels of N （0, 75, and 150 kg ha-1） were examined using 15N-labeled urea to evaluate N2 fixation via the 15N isotope dilution method. Treatments were designated NO （0.001 g per pot）, N75 （1.07 g per pot） and N150 （2.14 g per pot）. Alfalfa grown alone did not benefit from the addition of fertilizer N; dry matter was not significantly increased. In contrast, dry weight and N content of smooth bromegrass grown alone was increased significantly by N application. When grown as a mixture, smooth bromegrass biomass was increased significantly by N application, resulted in a decrease in alfalfa biomass. In addition, individual alfalfa plant dry weight （shoots＋roots） was significantly lower in the mixture than when grown alone at all N levels. Smooth bromegrass shoot and root dry weight were significantly higher when grown with alfalfa than when grown alone, regardless of N application level. When grown alone, alfalfa＇s N2 fixation was reduced with N fertilization （R2=0.9376,P=0.0057）. When grown in a mixture with smooth bromegrass, with 75 kg ha-1 of N fertilizer, the percentage of atmospheric N2 fixation contribution to total N in alfalfa （%Ndfa） had a maximum of 84.07 and 83.05% in the 2nd and 3rd harvests, respectively. Total 3-harvest %Ndfa was higher when alfalfa was grown in a mixture than when grown alone （shoots： ｜t｜=3.39, P=0.0096; root： ｜t｜=3.57, P=0.0073）. We believe this was due to smooth bromegrass being better able to absorb available soil N （due to its fibrous root system）, resulting inlower soil N availability and allowing alfalfa to develop an effective N2 fixing symbiosis prior to the 1st harvest. Once soil N levels were depleted, alfalfa was able to fix N2, resulting in the majority of its tissue N being derived from biological nitrogen fixation （BNF） in the 2nd and 3rd harvests. When grown in a mixture, with added N, alfalfa established an effective symbiosis earlier than when grown alone; in monoculture BNF did not contribute a significant portion of plant N in the N75 and N150 treatments, whereas in the mixture, BNF contributed 17.90 and 16.28% for these treatments respectively. Alfalfa has a higher BNF efficiency when grown in a mixture, initiating BNF earlier, and having higher N2 fixation due to less inhibition by soil-available N. For the greatest N-use-efficiency and sustainable production, grass-legume mixtures are recommended for imDrovino orasslands, usino a moderate amount of N fertilizer （75 kq N ha-l） to provide optimum benefits.
基金financially supported by the Agricultural Linkages Programme (ALP) of Pakistan Agricultural Research Council (PARC) (ALP/PARC) (No.CS-268) on Microbial Biotechnology for Sustainable Production of LegumesProf.Dr.Zahir A.Zahir, Soil Microbiology & Biochemistry Laboratory, Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad, Pakistan, for providing financial and logistic support to carry out the present investigation
文摘Legume plants are an essential component of sustainable farming systems.Phosphorus(P) deficiency is a significant constraint for legume production, especially in nutrient-poor soils of arid and semi-arid regions.In the present study, we conducted a pot experiment to evaluate the effects of a phosphorus-mobilizing plant-growth promoting rhizobacterial strain Bacillus cereus GS6, either alone or combined with phosphate-enriched compost(PEC) on the symbiotic(nodulation-N_2 fixation) performance of soybean(Glycine max(L.) Merr.) on an Aridisol.The PEC was produced by composting food waste with addition of single super phosphate.The bacterial strain B.cereus GS6 showed considerable potential for P solubilization and mobilization by releasing carboxylates in insoluble P(rock phosphate)-enriched medium.Inoculation of B.cereus GS6 in combination with PEC application significantly improved nodulation and nodule N_2 fixation efficiency.Compared to the control(without B.cereus GS6 and PEC), the combined application of B.cereus GS6 with PEC resulted in significantly higher accumulation of nitrogen(N), P, and potassium(K) in grain, shoot, and nodule.The N:P and P:K ratios in nodules were significantly altered by the application of PEC and B.cereus GS6, which reflected the important roles of P and K in symbiotic performance of soybean.The combined application of PEC and B.cereus GS6 also significantly increased the soil dehydrogenase and phosphomonoesterase activities, as well as the soil available N, P, and K contents.Significant positive relationships were found between soil organic carbon(C) content, dehydrogenase and phosphomonoesterase activities, and available N, P, and K contents.This study suggests that inoculation of P-mobilizing rhizobacteria, such as B.cereus GS6, in combination with PEC application might enhance legume productivity by improving nodulation and nodule N_2 fixation efficiency.
文摘Cyanothece sp. 113 is a unicellular, aerobic, diazotrophic and photosynthetic marine cyanobacterium. The optimal medium for exopolysaccharide yield by the strain was 70.0 g/L of NaCl, and 0.9 g/L of MgSO4 based on the modified F/2 medium for cultivation of marine algae. The optimal cultivation condition for exopolysaccharide yield by this cyanobacterial strain was 29℃, aeration, and continuous illumination at 86.0 μE/M^2/S. Under the optimal conditions, over 18.4 g/L of exopolysaccharide was produced within 12 days. This was so far the highest exopolysaccharide yield produced with strains of Cyanothece sp. obtained.
基金financially supported by the National Natural Science Foundation of China(Grant No.22172144).
文摘This study aimed to prepare and apply a novel Pt/CdMoO_(4) composite photocatalyst for photocatalytic N2 fixation and tetracycline degradation. The Pt/CdMoO_(4) composite was subjected to comprehensive investigation on the morphology, structure, optical properties, and photoelectric chemical properties. The results demonstrate the dispersion of Pt nanoparticles on the CdMoO_(4) surface. Close contact between CdMoO_(4) and Pt was observed, resulting in the formation of a heterojunction structure at their contact region. Density functional theory calculation and Mott-Schottky analysis revealed that Pt possesses a higher work function value than CdMoO_(4), resulting in electron drift from CdMoO_(4) to Pt and the formation of a Schottky barrier. The presence of this barrier increases the separation efficiency of electron-hole pairs, thereby improving the performance of the Pt/CdMoO_(4) composite in photocatalysis. When exposed to simulated sunlight, the optimal Pt/CdMoO_(4) catalyst displayed a photocatalytic nitrogen fixation rate of 443.7 μmol·L‒^(1)·g‒^(1)·h‒^(1), which is 3.2 times higher than that of pure CdMoO_(4). In addition, the composite also exhibited excellent performance in tetracycline degradation, with hole and superoxide species identified as the primary reactive species. These findings offer practical insights into designing and synthesizing efficient photocatalysts for photocatalytic nitrogen fixation and antibiotics removal.
基金the financial support provided by the Ministry of Higher Education(MOHE)Malaysia under the Fundamental Research Grant Scheme(FRGS)(No.FRGS/1/2020/TK0/XMU/02/1)the Guangdong Basic and Applied Basic Research Foundation(No.2021A1515111019)+1 种基金funded by Xiamen University Malaysia Investigatorship Grant(No.IENG/0038),Xiamen University Malaysia Research Fund(Nos.XMUMRF/2021-C8/IENG/0041 and XMUMRF/2019-C3/IENG/0013)Hengyuan International Sdn.Bhd.(No.EENG/0003).
文摘With the fast-pace digitalization evolution in the current generation’s lifestyle and the industry revolution,the energy demand has been skyrocketed.Recently,the two-dimensional(2D)bismuth-based nanomaterials emerged as a promising photocatalyst candidate in solar fuel conversion,not only for its exceptional light absorption capability and tunable optical properties,but it also can be synthesized into diverse variety of nanomaterials with different ranges of potential gap and band position to fulfill the potential requirement of wide range of photocatalytic reaction.Yet,the weak light harvesting ability and ultrafast charge recombination has restricted its potential in commercial application.Thus,recent researches have been focusing on tackling these issues by incorporating some modification strategies such as heteroatom doping,vacancy engineering,facet engineering,bismuth rich strategy and heterojunction engineering.Herein,this review article presents the state-of-the-art modifications on 2D bismuth-based parent material,specifically on the relationship between each of the modification strategy on the electronic properties and surface chemistry in achieving boosted photocatalytic performance.In the view of the unique charge interaction between two semiconductors with different dimensions,we systematically discuss the rational heterostructure design from the dimensionality perspective,namely,point-to-face,line-to-face,face-to-face,and bulk-to-face in solar fuel conversion to provide inspiring insights for future interface engineering.Finally,the challenges and the future research outlook in the solar-to-fuel conversion are highlighted to push forward the design of high-performance bismuth-based photocatalyst in realizing commercialscale solar-to-fuel conversion.
文摘Cyanobacterium offers a promising chassis for phototrophic production of renewable chemicals. Although engineered cyanobacteria can achieve similar product carbon yields as heterotrophic microbial hosts, their production rate and titer under photoautotrophic conditions are 10 to 100 folds lower than those in fast growing E. colt. Cyanobacterial factories face three indomitable bottlenecks. First, photosynthesis has limited ATP and NADPH generation rates. Second, CO2 fixation by ribulose-l,5-bisphosphate carboxylase/oxygenase （RuBisCO） has poor efficiency. Third, CO2 mass transfer and light supply are deficient within large photobioreac- tors. On the other hand, cyanobacteria may employ organic substrates to promote phototrophic cell growth, Nz fixation, and metabolite synthesis. The photo-fermenta- tions show enhanced photosynthesis, while CO2 loss from organic substrate degradation can be reused by the Calvin cycle. In addition, the plasticity of cyanobacterial path- ways （e.g., oxidative pentose phosphate pathway and the TCA cycle） has been recently revealed to facilitate the catabolism. The use of cyanobacteria as ＂green E. colt＂ could be a promising route to develop robust photobiorefineries.
