To estimate the relationships among bioleaching performance, additional elemental sulfur (S0), microbial population dynamics and its energy metabolism, bioleaching of chalcopyrite by three typical sulfur- and/or iro...To estimate the relationships among bioleaching performance, additional elemental sulfur (S0), microbial population dynamics and its energy metabolism, bioleaching of chalcopyrite by three typical sulfur- and/or iron-oxidizing bacteria, Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum and Acidithiobacillus thiooxidans with different levels of sulfur were studied in batch shake flask cultures incubated at 30 °C. Copper dissolution capability (71%) was increased with the addition of 3.193 g/L S0, compared to that (67%) without S0. However, lower copper extraction was obtained in bioleaching with excessive sulfur. Microbial population dynamics during chalcopyrite bioleaching process was monitored by using PCR-restriction fragment length polymorphism (PCR-RFLP). Additional S0 accelerated the growth of sulfur-oxidizing bacteria, inhibited the iron-oxidizing metabolism and led to the decrease of iron-oxidizing microorganisms, finally affected iron concentration, redox potential and bioleaching performance. It is suggested that mixed iron and sulfur-oxidizing microorganisms with further optimized additional S0 concentration could improve copper recovery from chalcopyrite.展开更多
The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receivin...The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.展开更多
The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium e...The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium extraction with over 90% at the Fe/S ratio of 5:0.5, 5:1 and 5:5, while poor extraction(<46%) at the Fe/S ratio of 5:0 and 5:10.Furthermore, the bacterial community analysis based on species-specific gyrB numbers indicated that, absent sulfur or excessive sulfur would be not conducive to the synergistic growth for A. ferrooxidans and A. thiooxidans, and then not conducive to the uranium dissolution. Meanwhile, the sulfur-oxidizers could play an important role in the process of uranium synergistic bioleaching by mixed bacterial consortia. Additionally, the characteristics of mineral residue was detected by SEM-EDS. The results showed appropriate sulfur dosage would change the structure and improve the porosity of passivation substance. Lastly, the uranium dissolution kinetics and biochemical reaction mechanism was analyzed. It indicated that the biochemical reaction coupling iron and sulfur had a pleiotropic effect on the uranium dissolution from the ore particles, appropriate Fe/S ratio is the key factor for uranium bioleaching by chemoautotrophic acidophiles.展开更多
The essential oil composition leaves of Juniperus communis L., Taxus canadensis Marshall. and Tsuga canadensis (L.) Carr. from Canada were investigated by head space solid phase microextraction (HS-SPME) and gas c...The essential oil composition leaves of Juniperus communis L., Taxus canadensis Marshall. and Tsuga canadensis (L.) Carr. from Canada were investigated by head space solid phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC-MS). Thirty-three, thirty and thirty-one components were identified representing 95.78%, 93.89%, 96.14% of the oil, respectively. Limonene (26.12%), benzene (15.62%), 13-mrycene (9.08%) and β-pinene (7.30%) were found to be the main constituents of J. communis; 1-propanone (36.38%), morpholine (10.95%), methylamine (9.10%) and methanone (8.14%) were detected main components of Taxus canadensis; bornylacetate (26.84%), α-pinene (23.74%), camphene (11.93%) and limonene (6.02%) were determined as major constituents of Tsuga canadensis. The chemical distributions of the essential oil compounds in the genus pattern were discussed in means of chemotaxonomy and natural products.展开更多
Six additives,i.e.,limestone,lime,magnesite,magnesia,dolomite and light-burned-dolomite,were added for investigating their influences on the pellet quality.For green balls,adding lime and light-burned-dolomite makes t...Six additives,i.e.,limestone,lime,magnesite,magnesia,dolomite and light-burned-dolomite,were added for investigating their influences on the pellet quality.For green balls,adding lime and light-burned-dolomite makes the wet drop strength decrease firstly,and then increase with further increase of additive dosage.Ca(OH)2 affects the bentonite properties at the beginning,but the binding property of Ca(OH)2 will be main when the dosage is higher.The other four additives decrease the drop strength for their disadvantageous physical properties.For preheated pellets,no mater what kind of additive is added,the compressive strength will be decreased because of unmineralized additives.For roasted pellets,calcium additives can form binding phase of calcium-ferrite,and suitable liquid phase will improve recrystallization of hematite,but excessive liquid will destroy the structure of pellets,so the compressive strength of pellet increases firstly and then drops.When adding magnesium additives,the strength will be decreased because of the oxidation of magnetite retarded by MgO.展开更多
The energy metabolism structure of microbial community plays an important role in the process of biohydrometallurgy.In this article,an artificial microbial community composed of three strains(Acidithiobacillus ferroox...The energy metabolism structure of microbial community plays an important role in the process of biohydrometallurgy.In this article,an artificial microbial community composed of three strains(Acidithiobacillus ferrooxidans,Leptospirillum ferriphilum and Acidithiobacillus thiooxidans)was used to leach three kinds of chalcopyrites with different iron-sulfur ratios.After 36 d of leaching,the chalcopyrite with iron-sulfur ratio of about 1:1 achieved the highest copper extraction(69.62%).In the early stage,iron oxidizing bacteria predominated,and the expression of rus and rio was 8 times higher than that in the late stage.In the late stage,sulfur oxidizing bacteria predominated,and the expression of tetH and HdrAB was 4 times higher than that in the early stage.Furthermore,the three bioleaching systems above were added with elemental sulfur(3 g/L);the chalcopyrite with iron-sulfur ratio of about 2:1 achieved the highest copper extraction(80.63%).The results suggest that the energy metabolism structure of the microbial community could be changed by changing the iron-sulfur ratio during the leaching process for improving the leaching efficiency of chalcopyrite.展开更多
The phenomenon of ground vibration amplification caused by railway traffic was found and proved. In order to study the reasons which cause the amplification, a drop-weight test was performed. Then, the model for both ...The phenomenon of ground vibration amplification caused by railway traffic was found and proved. In order to study the reasons which cause the amplification, a drop-weight test was performed. Then, the model for both homogeneous and layered soil subjected to a harmonic vertical load was built. With the help of this model, displacement Green's function was calculated and the propagation laws of ground vibration responses were discussed. Results show that: 1) When applying a harmonic load on the half-space surface, the amplitude of ground vibrations attenuate with fluctuation, which is caused by the superposition of bulk and Rayleigh waves. 2) Vibration amplification can be enlarged under the conditions of embedded source and the soil layers. 3) In practice, the fluctuant attenuation should be paid attention to especially for the vibration receivers who are sensitive to single low frequencies(<10 Hz). Moreover, for the case of embedded loads, it should also be paid attention to that the receivers are located at the place where the horizontal distance is similar to embedded depth, usually 10 to 30 m for metro lines.展开更多
Leptospirillum ferriphilum YSK was added to a native consortium of bioleaching bacteria including Acidithiobacillus caldus,A.thiooxidans,A.ferrooxidans,Sulfobacillus thermosulfidooxidans,Acidiphilium spp.,and Ferropla...Leptospirillum ferriphilum YSK was added to a native consortium of bioleaching bacteria including Acidithiobacillus caldus,A.thiooxidans,A.ferrooxidans,Sulfobacillus thermosulfidooxidans,Acidiphilium spp.,and Ferroplasma thermophilum cultured in modified 9K medium containing 0.5%(W/V)pyrite.The bioleaching efficiency markedly increased.Changes in community structure and gene expression were monitored with real-time PCR and functional gene arrays.Dynamic changes that varied in different populations in the consortium occurred after the addition of L.ferriphilum YSK,with growth of A.caldus S1,A.thiooxidans A01,Acidiphillum spp.DX1-1 promoted the growth of Ferroplasma L1,inhibited that of S.thermosulfidooxidans ST,and exerted little effect on that of A.ferrooxidans CMS.Genes encoding ADP heptose,phosphoheptose isomerase,glycosyltransferase,biotin carboxylase,and protoheme ferrolyase from L.ferriphilum,acetyl-CoA carboxylase from Acidiphillum spp.,and doxD from A.caldus were up-regulated in 0-20 h.Genes encoding lipid A disaccharide synthase LpxB,glycosyl transferase,and ADP heptose synthase from A.ferrooxidans were up-regulated in 0-8 h and then down-regulated in 8-20 h.Genes encoding ferredoxin oxidoreductase from Ferroplasma sp.were up-regulated in 0-4 h,down-regulated in 4-16 h,and again up-regulated in 16-20 h.CbbS from A.ferrooxidans was down-regulated in 0-20 h.展开更多
To reveal the effects of Fe2+ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage (AMD) samples were collected at Dabaoshan Mine and Shenbu Mine. Community success...To reveal the effects of Fe2+ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage (AMD) samples were collected at Dabaoshan Mine and Shenbu Mine. Community successions of AMD niches were analyzed by Amplified Ribosomal DNA Restriction Analysis (ARDRA), sequencing, and phylogenetic analysis in original AMD samples and their subculture under Fe2+ concentrations. Although geochemical properties and community structures were greatly different between the two original AMD samples, bacterial community successions were still very similar under high Fe2+ concentrations. The results showed that Acidithiobacillus ferrooxidans have competitive relationship with other bacterial species living in the AMD, including species that were also capable of oxidizing ferrous ion. A competitive relationship among different At. ferrooxidans strains likewise existed. Some of At. ferrooxidans can grow first under conditions of high ferrous ion concentration, and other At. ferrooxidans species decreased gradually and disappeared. This suggested that these species of At. ferrooxidans are most acidophilic bacteria and afford Fe3+ to leach other metallic ion in the early stages of minerals dissolution.展开更多
The denitrifying sulfide removal(DSR) process has recently been studied extensively from an engineering perspective. However, the importance of microbial communities of this process was generally underestimated. In th...The denitrifying sulfide removal(DSR) process has recently been studied extensively from an engineering perspective. However, the importance of microbial communities of this process was generally underestimated. In this study, the microbial community structure of a lab-scale DSR reactor was characterized in order to provide a comprehensive insight into the key microbial groups in DSR system. Results from high-throughput sequencing analysis revealed that the fraction of autotrophic denitrifiers increased from 2.34 % to 10.93% and 44.51% in the DSR system when the influent Na Cl increased from 0 g/L, to 4 g/L and 30 g/L, respectively. On the contrary, the fraction of heterotrophic denitrifiers decreased from 61.74% to 39.57%, and 24.12%, respectively. Azoarcus and Thiobacillus were the main autotrophic denitrifiers, and Thauera was the main hetetrophic denitrifier during the whole process. This study could be useful for better understanding the interaction between autotrophs and heterotrophs in DSR system.展开更多
Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under mic...Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.展开更多
The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories an...The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories and expression forms of the change rate arededuced,including acceleration and deceleration cases.These modified models provide more accurate and realisticapproximations in modeling rapidly fading channels.展开更多
基金Project (20803094) supported by the National Natural Science Foundation of ChinaProject (20100471233) supported by the Postdoctoral Foundation of China and the Postdoctoral Foundation of Central South University
文摘To estimate the relationships among bioleaching performance, additional elemental sulfur (S0), microbial population dynamics and its energy metabolism, bioleaching of chalcopyrite by three typical sulfur- and/or iron-oxidizing bacteria, Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum and Acidithiobacillus thiooxidans with different levels of sulfur were studied in batch shake flask cultures incubated at 30 °C. Copper dissolution capability (71%) was increased with the addition of 3.193 g/L S0, compared to that (67%) without S0. However, lower copper extraction was obtained in bioleaching with excessive sulfur. Microbial population dynamics during chalcopyrite bioleaching process was monitored by using PCR-restriction fragment length polymorphism (PCR-RFLP). Additional S0 accelerated the growth of sulfur-oxidizing bacteria, inhibited the iron-oxidizing metabolism and led to the decrease of iron-oxidizing microorganisms, finally affected iron concentration, redox potential and bioleaching performance. It is suggested that mixed iron and sulfur-oxidizing microorganisms with further optimized additional S0 concentration could improve copper recovery from chalcopyrite.
基金Project of Science and Technology Research and Development Plan of China Railway Corporation(No.2013G010-D)Foundation of a Hundred Youth Talent Training Program of Lanzhou Jiaotong University
文摘The user signal quality as well as the performance of transmission link experiences severe loss due to wireless channel fading and propagation loss in high-speed railway scenario.To improve the quality at the receiving end,spatial diversity was realized by means of cooperative communication technology based on the uncorrelated characteristics of the channels.The model of mobile communication system in high-speed railway was set up,and a cooperative scheme based on statistics was proposed.Mathematical analysis and simulation results show that the quality of the received signal and the performance of the transmission link are significantly improved using cooperative communication technology compared to that in non-cooperative communication mode.
基金Project(51804165) supported by the National Natural Science Foundation of ChinaProject(2018JJ3441) supported by the Natural Science Foundation of Hunan Province,China。
文摘The role of Fe/S ratios(ω, g/g) in the uranium bioleaching from a complex uranium ore by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans consortium was investigated. The results showed good uranium extraction with over 90% at the Fe/S ratio of 5:0.5, 5:1 and 5:5, while poor extraction(<46%) at the Fe/S ratio of 5:0 and 5:10.Furthermore, the bacterial community analysis based on species-specific gyrB numbers indicated that, absent sulfur or excessive sulfur would be not conducive to the synergistic growth for A. ferrooxidans and A. thiooxidans, and then not conducive to the uranium dissolution. Meanwhile, the sulfur-oxidizers could play an important role in the process of uranium synergistic bioleaching by mixed bacterial consortia. Additionally, the characteristics of mineral residue was detected by SEM-EDS. The results showed appropriate sulfur dosage would change the structure and improve the porosity of passivation substance. Lastly, the uranium dissolution kinetics and biochemical reaction mechanism was analyzed. It indicated that the biochemical reaction coupling iron and sulfur had a pleiotropic effect on the uranium dissolution from the ore particles, appropriate Fe/S ratio is the key factor for uranium bioleaching by chemoautotrophic acidophiles.
文摘The essential oil composition leaves of Juniperus communis L., Taxus canadensis Marshall. and Tsuga canadensis (L.) Carr. from Canada were investigated by head space solid phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC-MS). Thirty-three, thirty and thirty-one components were identified representing 95.78%, 93.89%, 96.14% of the oil, respectively. Limonene (26.12%), benzene (15.62%), 13-mrycene (9.08%) and β-pinene (7.30%) were found to be the main constituents of J. communis; 1-propanone (36.38%), morpholine (10.95%), methylamine (9.10%) and methanone (8.14%) were detected main components of Taxus canadensis; bornylacetate (26.84%), α-pinene (23.74%), camphene (11.93%) and limonene (6.02%) were determined as major constituents of Tsuga canadensis. The chemical distributions of the essential oil compounds in the genus pattern were discussed in means of chemotaxonomy and natural products.
基金Project(2008BAB32B06) supported by the Key Projects in the National Science and Technology Pillar Program during the 11th Five-year Plan PeriodProject(2009ybfz20) supported by the Program for Excellent Doctor’s Degree Paper in Central South University,ChinaProject(1343/74333001114) supported by the Postgraduate’s Paper Innovation Fund of Hunan Province,China
文摘Six additives,i.e.,limestone,lime,magnesite,magnesia,dolomite and light-burned-dolomite,were added for investigating their influences on the pellet quality.For green balls,adding lime and light-burned-dolomite makes the wet drop strength decrease firstly,and then increase with further increase of additive dosage.Ca(OH)2 affects the bentonite properties at the beginning,but the binding property of Ca(OH)2 will be main when the dosage is higher.The other four additives decrease the drop strength for their disadvantageous physical properties.For preheated pellets,no mater what kind of additive is added,the compressive strength will be decreased because of unmineralized additives.For roasted pellets,calcium additives can form binding phase of calcium-ferrite,and suitable liquid phase will improve recrystallization of hematite,but excessive liquid will destroy the structure of pellets,so the compressive strength of pellet increases firstly and then drops.When adding magnesium additives,the strength will be decreased because of the oxidation of magnetite retarded by MgO.
基金Project(2017zzts382)supported by Central South University Postgraduate Independent Exploration and Innovation,ChinaProject(2014jpkc003)supported by Central South University Graduate Excellent Course,China+1 种基金Project(2015JJ2165)supported by Hunan Provincial Natural Science Foundation of ChinaProject(165611031)supported by Central South University Fundamental Research Funds Special Funding,China。
文摘The energy metabolism structure of microbial community plays an important role in the process of biohydrometallurgy.In this article,an artificial microbial community composed of three strains(Acidithiobacillus ferrooxidans,Leptospirillum ferriphilum and Acidithiobacillus thiooxidans)was used to leach three kinds of chalcopyrites with different iron-sulfur ratios.After 36 d of leaching,the chalcopyrite with iron-sulfur ratio of about 1:1 achieved the highest copper extraction(69.62%).In the early stage,iron oxidizing bacteria predominated,and the expression of rus and rio was 8 times higher than that in the late stage.In the late stage,sulfur oxidizing bacteria predominated,and the expression of tetH and HdrAB was 4 times higher than that in the early stage.Furthermore,the three bioleaching systems above were added with elemental sulfur(3 g/L);the chalcopyrite with iron-sulfur ratio of about 2:1 achieved the highest copper extraction(80.63%).The results suggest that the energy metabolism structure of the microbial community could be changed by changing the iron-sulfur ratio during the leaching process for improving the leaching efficiency of chalcopyrite.
基金Project(51278043)supported by National Natural Science Foundation of China
文摘The phenomenon of ground vibration amplification caused by railway traffic was found and proved. In order to study the reasons which cause the amplification, a drop-weight test was performed. Then, the model for both homogeneous and layered soil subjected to a harmonic vertical load was built. With the help of this model, displacement Green's function was calculated and the propagation laws of ground vibration responses were discussed. Results show that: 1) When applying a harmonic load on the half-space surface, the amplitude of ground vibrations attenuate with fluctuation, which is caused by the superposition of bulk and Rayleigh waves. 2) Vibration amplification can be enlarged under the conditions of embedded source and the soil layers. 3) In practice, the fluctuant attenuation should be paid attention to especially for the vibration receivers who are sensitive to single low frequencies(<10 Hz). Moreover, for the case of embedded loads, it should also be paid attention to that the receivers are located at the place where the horizontal distance is similar to embedded depth, usually 10 to 30 m for metro lines.
基金Projects(51604308,41771300,41301274)supported by the National Natural Science Foundation of ChinaProject(2017QNCXTD_GTD)supported by the Youth Innovation Team Project of Institute of Subtropical Agriculture,Chinese Academy of Sciences+1 种基金Project(2017YFD0202000)supported by the National Key Research and Development Program of ChinaProject(2020GDASYL-20200402001)supported by the special Project of Science and Technology Development,China。
文摘Leptospirillum ferriphilum YSK was added to a native consortium of bioleaching bacteria including Acidithiobacillus caldus,A.thiooxidans,A.ferrooxidans,Sulfobacillus thermosulfidooxidans,Acidiphilium spp.,and Ferroplasma thermophilum cultured in modified 9K medium containing 0.5%(W/V)pyrite.The bioleaching efficiency markedly increased.Changes in community structure and gene expression were monitored with real-time PCR and functional gene arrays.Dynamic changes that varied in different populations in the consortium occurred after the addition of L.ferriphilum YSK,with growth of A.caldus S1,A.thiooxidans A01,Acidiphillum spp.DX1-1 promoted the growth of Ferroplasma L1,inhibited that of S.thermosulfidooxidans ST,and exerted little effect on that of A.ferrooxidans CMS.Genes encoding ADP heptose,phosphoheptose isomerase,glycosyltransferase,biotin carboxylase,and protoheme ferrolyase from L.ferriphilum,acetyl-CoA carboxylase from Acidiphillum spp.,and doxD from A.caldus were up-regulated in 0-20 h.Genes encoding lipid A disaccharide synthase LpxB,glycosyl transferase,and ADP heptose synthase from A.ferrooxidans were up-regulated in 0-8 h and then down-regulated in 8-20 h.Genes encoding ferredoxin oxidoreductase from Ferroplasma sp.were up-regulated in 0-4 h,down-regulated in 4-16 h,and again up-regulated in 16-20 h.CbbS from A.ferrooxidans was down-regulated in 0-20 h.
文摘To reveal the effects of Fe2+ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage (AMD) samples were collected at Dabaoshan Mine and Shenbu Mine. Community successions of AMD niches were analyzed by Amplified Ribosomal DNA Restriction Analysis (ARDRA), sequencing, and phylogenetic analysis in original AMD samples and their subculture under Fe2+ concentrations. Although geochemical properties and community structures were greatly different between the two original AMD samples, bacterial community successions were still very similar under high Fe2+ concentrations. The results showed that Acidithiobacillus ferrooxidans have competitive relationship with other bacterial species living in the AMD, including species that were also capable of oxidizing ferrous ion. A competitive relationship among different At. ferrooxidans strains likewise existed. Some of At. ferrooxidans can grow first under conditions of high ferrous ion concentration, and other At. ferrooxidans species decreased gradually and disappeared. This suggested that these species of At. ferrooxidans are most acidophilic bacteria and afford Fe3+ to leach other metallic ion in the early stages of minerals dissolution.
基金supported by the National Natural Science Foundation of China under Grant No.21307160the Natural Science Foundation of Shandong Province under Grant No.ZR2013EEQ030the Fundamental Research Funds for the Central Universities under Grant No.R1404005A
文摘The denitrifying sulfide removal(DSR) process has recently been studied extensively from an engineering perspective. However, the importance of microbial communities of this process was generally underestimated. In this study, the microbial community structure of a lab-scale DSR reactor was characterized in order to provide a comprehensive insight into the key microbial groups in DSR system. Results from high-throughput sequencing analysis revealed that the fraction of autotrophic denitrifiers increased from 2.34 % to 10.93% and 44.51% in the DSR system when the influent Na Cl increased from 0 g/L, to 4 g/L and 30 g/L, respectively. On the contrary, the fraction of heterotrophic denitrifiers decreased from 61.74% to 39.57%, and 24.12%, respectively. Azoarcus and Thiobacillus were the main autotrophic denitrifiers, and Thauera was the main hetetrophic denitrifier during the whole process. This study could be useful for better understanding the interaction between autotrophs and heterotrophs in DSR system.
基金funded by the National Natural Science Foundations of China(41420104007,41330857,and 41701295)Guangdong Natural Science Funds for Distinguished Young Scholar(2014A030306041)and Special Support Program(2016)
文摘Iron oxidation is a prevalent and important biogeochemical process in paddy soil,but little is known about whether and how microbially mediated iron oxidation is coupled with carbon assimilation,particularly under microaerobic conditions.Here,we investigated kinetics of CO_2 assimilation and Fe(Ⅱ)oxidation in an incubation experiment with paddy soil under suboxic conditions,and profiled the associated microbial community using DNA-stable isotope probing and 16S r RNA gene-based sequencing.The results showed that CO_2 assimilation and Fe(II)oxidation in the gradient tubes were predominantly mediated by the microbes enriched in the paddy soil,primarily Azospirillum and Magnetospirillum,as their relative abundances were higher in the^( 13)C heavy fractions compared to^( 12)C heavy fractions.This study provided direct evidence of chemoautotrophic microaerophiles linking iron oxidation and carbon assimilation at the oxic–anoxic interface in the paddy soil ecosystem.
基金supported in part by the NSFC Project under Grants No.61371070Fundamental Research Funds for the Central Universities under grant2015JBM011+2 种基金the Beijing Nova Programme(No.xx2016023)the Open Research Fund of National Mobile Communications Research Laboratory,Southeast University,under Grant No.2012D07Beijing Natural Science Foundation project under grant No.4142041
文摘The varying trajectory of Doppler frequency under changing speed motion conditionsare investigated in Highspeed Railway(HSR) scenarios.Based on the geometrical physical parameters,instantaneous Doppler trajectories and expression forms of the change rate arededuced,including acceleration and deceleration cases.These modified models provide more accurate and realisticapproximations in modeling rapidly fading channels.