After mass extinctions, most areas became “ecologically barren areas” lacking or even without ecosystem over an extensive region. Studying the pioneer organisms and the reconstruction process of a new ecosystem in t...After mass extinctions, most areas became “ecologically barren areas” lacking or even without ecosystem over an extensive region. Studying the pioneer organisms and the reconstruction process of a new ecosystem in the “ecologically barren area” is very important for revealing the evo- lution after bio-mass extinctions. In the Dushan region, Guizhou Province, China, the trace fossils appeared and flourished evidently earlier than body fossils after Frasnian-Famennian (F-F) mass extinction. The pioneer organisms and pathfinders in the “ecologically barren areas” are the trace-makers that are deposit-feeders with relatively simple structure and conformation on or near the deposit surface. The trace-makers have undergone an evolutionary process that their trace structures changed from simple to complex, and their living and moving areas and spaces enlarged from linear to planar and then to three-dimension spaces. Those characters show that the ability of the trace-makers to deposits and their efficiency of looking for food have been enhanced gradually and that those trace-makers constructed gradually a base for the new ecosystem. This process is similar to that of the trace fossils near the Precambrian-Cambrian boundary. In the Dushan area, only the recovery intervals have been identified for the Famennian body fossils, with no eminent radiation interval recognizable due to the Devonian-Carboniferous (C-D) mass ex- tinction. However, both the recovery and radiation intervals may be clearly recognized in the Famen- nian trace fossils based on their conformation and diversity. The evolution and diversification of the trace fossils in the “ecologically barren area” is considered to have played a role of necessary foun- dation for the recovery of body fossils in the ecological chain. With the gradual disappearance of the unfavourable environment factors resulting in the F-F mass extinction, a new ecosystem was reconstructed in the “ecologically barren area” through a three-step process from the “ori展开更多
Two positive d 13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbon-ate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attrib...Two positive d 13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbon-ate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attrib-uted to enhanced organic carbon burial during the F-F biological mass extinction. However, this worldwide pattern has not been revealed from the well-deposited Late Devonian sequences in southern China. In this paper, a detailed inves-tigation has been made on the Late Devonian section at Dongcun, Guilin, southern China to constrain perturbations in d 13C of carbonates in the F-F deposited sequence. The result from this section also indicates two positive d 13C ex-cursions during the F-F transition. The first excursion with an amplitude of 1.5 occurred at the bottom of linguiformis Zone, later than the early excursion existing in the Late rhe-nana Zone of the Late Devonian profiles in other continents, especially, in central Europe. This difference has been ex-pected to be a result as conodont Palmatolepis linguiformis occurred earlier in southern China than other sites. The second excursion with an amplitude of 2.1 is located at the F-F boundary, same as the records from other continents. This result strongly supports the view that two carbon iso-tope positive excursions during the F-F transition are com-mon in carbonate sediments, resulting from worldwide in-creases of organic carbon burial intensity.展开更多
The abundance curves derived from area proportions of brachiopods and Girvanella in the thin sections from the Yangdi section, South China, exhibits complex relationships during the Late Devonian Frasnian-Famennian tr...The abundance curves derived from area proportions of brachiopods and Girvanella in the thin sections from the Yangdi section, South China, exhibits complex relationships during the Late Devonian Frasnian-Famennian transition. The living activity of brachiopods such as grazing and borrowing did great damage to the growth of Girvanella. However, there was more to just a mere a survival competing relationship between them, Girvanella actually improved marine environments by oxygenating the dysoxic ambient sea-water through photosynthesis in the lower Kellwasser Horizon. Profited from this improvement brachiopods' abundance increased subsequently and suppressed Girvanella again. Nonetheless, without Girvanella's photosynthesis, brachiopods were wiped out by the farther anoxic environments in the upper Kellwasser Horizon. The complex relationships between Girvanella and brachiopods may be a key to unlocking the relationships between geomicrobes and metazoans in the geological overturn periods.展开更多
Q Sepharose Fast Flow(Q Sepharose F.F.) was adopted to purify the suspensions of type Ⅰ,Ⅱ,Ⅲ oral poliovaccine (OPV), which is prepared from Vero cells. After clarification and concentration by ultrafiltration,th...Q Sepharose Fast Flow(Q Sepharose F.F.) was adopted to purify the suspensions of type Ⅰ,Ⅱ,Ⅲ oral poliovaccine (OPV), which is prepared from Vero cells. After clarification and concentration by ultrafiltration,the recovery of virus infected titre may attain above 85%.Using column chromatography on Q Sepharose F.F. to purify the concentrated virus suspensions,the purified viruses attain 100% recovery of virus infectivity. Dot membrane hybrization was used to detect DNA with the probe of Vero cell genome DNA which was labeled with α P 32 dATP,the contents of residual substrate DNA was less than 100 Pg/dose. The process of downstream had no significant influence on some biological characters of purified viruses,such as virus morphology ,tumorigenicity, rct/40 character and capsid protein.This downstream reseach indicates that Q Sepharose F.F. is an ideal chromatography material for purifying OPV prepared from Vero cells.展开更多
Abundant perfectly-preserved phosphatic microspherules have been discovered across the Frasnian-Famennian （F-F） transition from the Yangdi section in Guilin, Guangxi, South China. They are mostly spherical or ellipt...Abundant perfectly-preserved phosphatic microspherules have been discovered across the Frasnian-Famennian （F-F） transition from the Yangdi section in Guilin, Guangxi, South China. They are mostly spherical or elliptical in shape and about 150 gin in diameter with smooth exterior surfaces. Each microspherule consistently possesses a small dimple on the surface. The internal texture of microspherules consists of concentric light-colored apatite and dark-colored organic matter bands alternating around a central core. Conodonts have also been found preserved together with phosphatic microspherules in the same horizon, and the abundance of the former is obviously higher than that of the latter. Laser Raman spectral studies show close similarities in spectral patterns between the outer shells of phosphatic microspherules and the blade of the conodont genus Palmatolepis sp., as well as between the microspherule nucleus and the platform of the same conodont genus. Furthermore, the statistical results and geochemical data demonstrate that the elevated abundance of phosphatic microspherules roughly coincides with the blooms of bacteria and algae, but is later than the sharp increase of oceanic nutrients. The phosphatic microspherules are inter- preted here to be the ＇otoliths＇ secreted by conodont animals based on the compositional similarities between phosphatic mi- crospherules and conodonts and their interrelated abundances. In addition, an analogous study reveals morphological and tex- tural similarities between fish otoliths and phosphatic microspherules. The formation of phosphatic microspherules is probably related to seawater eutrophication. We speculate that the explosive growth of bacteria and algae is probably caused by the en- richment of nutrients that is most likely associated with the increase of terrestrial inputs, submarine hydrothermal activities or the upwelling anoxic bottom waters in the late Devonian, which would stimulate the conodont animals to secrete phosphatic microspherules--the ＇otoli展开更多
In this paper,we designed Eu^(2+)-doped BaAlF_(5) and BaSiF_(6) downconversion nanophosphors with strong f-f transition emission to realize the quantitative detection of TNP.The surface of the as-prepared nanophosphor...In this paper,we designed Eu^(2+)-doped BaAlF_(5) and BaSiF_(6) downconversion nanophosphors with strong f-f transition emission to realize the quantitative detection of TNP.The surface of the as-prepared nanophosphors was modified by polyethylenimine(PEI) to increase the water solubility and to provide a pair of electrons to bind to the benzene ring in TNP,forming a Meisenheimer complex.The detection principle of TNP is based on luminescence resonance energy transfer(LRET) technology,where the PEI-functionalized BaAlF_(5):Eu^(2+) and BaSiF_(6):Eu^(2+) nanophosphors are used as energy donors and TNP is an energy acceptor.With increasing TNP concentrations,the luminescence intensity of the BaAlF5:Eu^(2+) and BaSiF6:Eu^(2+) nanophosphors at 359 nm [^(4)f_(7)(^(6)P_(7/2))→^(4)f_(7)(^(8)S_(7/2)) transition of Eu^(2+)] displays dramatic luminescent quenching.The BaAlF_(5):Eu^(2+)@PEI or BaSiF_(6):Eu^(2+)@PEI nanophosphor downconversion luminescent sensors show great sensitivity and selectivity and good linearity,and the detection limits of TNP are 0.57 and 2.82 ng/mL,respectively.展开更多
The complexation of pentavalent neptunium,Np(Ⅴ),with nitrate ion in an ionic liquid solution has been studied spectroscopically for the first time.The characteristic f-f transition absorption band of Np(Ⅴ)in the NIR...The complexation of pentavalent neptunium,Np(Ⅴ),with nitrate ion in an ionic liquid solution has been studied spectroscopically for the first time.The characteristic f-f transition absorption band of Np(Ⅴ)in the NIR region changes significantly upon the titration of nitrate ion into the solution,revealing strong complexation of Np(Ⅴ)with nitrate ion in the ionic liquid.Most notably,the absorption band of Np(Ⅴ)almost disappears when a sufficiently high concentration of nitrate ion is present in the solution.Such a rare optically“silent”species can be assigned to the 1:2 Np(Ⅴ)/nitrate complex with a centrosymmetric coordination environment where Np sits at the inversion center.展开更多
基金supported by the National Natural Science F oundation of China(Grant No.40172014)the Guizhou University Foundation.
文摘After mass extinctions, most areas became “ecologically barren areas” lacking or even without ecosystem over an extensive region. Studying the pioneer organisms and the reconstruction process of a new ecosystem in the “ecologically barren area” is very important for revealing the evo- lution after bio-mass extinctions. In the Dushan region, Guizhou Province, China, the trace fossils appeared and flourished evidently earlier than body fossils after Frasnian-Famennian (F-F) mass extinction. The pioneer organisms and pathfinders in the “ecologically barren areas” are the trace-makers that are deposit-feeders with relatively simple structure and conformation on or near the deposit surface. The trace-makers have undergone an evolutionary process that their trace structures changed from simple to complex, and their living and moving areas and spaces enlarged from linear to planar and then to three-dimension spaces. Those characters show that the ability of the trace-makers to deposits and their efficiency of looking for food have been enhanced gradually and that those trace-makers constructed gradually a base for the new ecosystem. This process is similar to that of the trace fossils near the Precambrian-Cambrian boundary. In the Dushan area, only the recovery intervals have been identified for the Famennian body fossils, with no eminent radiation interval recognizable due to the Devonian-Carboniferous (C-D) mass ex- tinction. However, both the recovery and radiation intervals may be clearly recognized in the Famen- nian trace fossils based on their conformation and diversity. The evolution and diversification of the trace fossils in the “ecologically barren area” is considered to have played a role of necessary foun- dation for the recovery of body fossils in the ecological chain. With the gradual disappearance of the unfavourable environment factors resulting in the F-F mass extinction, a new ecosystem was reconstructed in the “ecologically barren area” through a three-step process from the “ori
文摘Two positive d 13C excursions are presented in records from the Frasnian-Famennian (F-F) marine carbon-ate sediments in Europe, America, Africa, and Australia, having been considered as a worldwide pattern, and attrib-uted to enhanced organic carbon burial during the F-F biological mass extinction. However, this worldwide pattern has not been revealed from the well-deposited Late Devonian sequences in southern China. In this paper, a detailed inves-tigation has been made on the Late Devonian section at Dongcun, Guilin, southern China to constrain perturbations in d 13C of carbonates in the F-F deposited sequence. The result from this section also indicates two positive d 13C ex-cursions during the F-F transition. The first excursion with an amplitude of 1.5 occurred at the bottom of linguiformis Zone, later than the early excursion existing in the Late rhe-nana Zone of the Late Devonian profiles in other continents, especially, in central Europe. This difference has been ex-pected to be a result as conodont Palmatolepis linguiformis occurred earlier in southern China than other sites. The second excursion with an amplitude of 2.1 is located at the F-F boundary, same as the records from other continents. This result strongly supports the view that two carbon iso-tope positive excursions during the F-F transition are com-mon in carbonate sediments, resulting from worldwide in-creases of organic carbon burial intensity.
基金NSFC Innovation Research Group Program (Grant No. 40621002)MOE Innovative Research Team Program (Grant No. IRT0546)+1 种基金the National Natural Science Foundation of China (Grant Nos. 40472020, 40730209, 40802005 and 40872001)SINOPEC Project (Grant No. G0800-06-ZS-319)
文摘The abundance curves derived from area proportions of brachiopods and Girvanella in the thin sections from the Yangdi section, South China, exhibits complex relationships during the Late Devonian Frasnian-Famennian transition. The living activity of brachiopods such as grazing and borrowing did great damage to the growth of Girvanella. However, there was more to just a mere a survival competing relationship between them, Girvanella actually improved marine environments by oxygenating the dysoxic ambient sea-water through photosynthesis in the lower Kellwasser Horizon. Profited from this improvement brachiopods' abundance increased subsequently and suppressed Girvanella again. Nonetheless, without Girvanella's photosynthesis, brachiopods were wiped out by the farther anoxic environments in the upper Kellwasser Horizon. The complex relationships between Girvanella and brachiopods may be a key to unlocking the relationships between geomicrobes and metazoans in the geological overturn periods.
文摘Q Sepharose Fast Flow(Q Sepharose F.F.) was adopted to purify the suspensions of type Ⅰ,Ⅱ,Ⅲ oral poliovaccine (OPV), which is prepared from Vero cells. After clarification and concentration by ultrafiltration,the recovery of virus infected titre may attain above 85%.Using column chromatography on Q Sepharose F.F. to purify the concentrated virus suspensions,the purified viruses attain 100% recovery of virus infectivity. Dot membrane hybrization was used to detect DNA with the probe of Vero cell genome DNA which was labeled with α P 32 dATP,the contents of residual substrate DNA was less than 100 Pg/dose. The process of downstream had no significant influence on some biological characters of purified viruses,such as virus morphology ,tumorigenicity, rct/40 character and capsid protein.This downstream reseach indicates that Q Sepharose F.F. is an ideal chromatography material for purifying OPV prepared from Vero cells.
基金supported by National Basic Research Program of China (Grant No. 2011CB808800)National Natural Science Foundation of China (Grant Nos. 41290260, 41072252)Doctoral Fund of Ministry of Education of China (Grant No. 20120145110012)
文摘Abundant perfectly-preserved phosphatic microspherules have been discovered across the Frasnian-Famennian （F-F） transition from the Yangdi section in Guilin, Guangxi, South China. They are mostly spherical or elliptical in shape and about 150 gin in diameter with smooth exterior surfaces. Each microspherule consistently possesses a small dimple on the surface. The internal texture of microspherules consists of concentric light-colored apatite and dark-colored organic matter bands alternating around a central core. Conodonts have also been found preserved together with phosphatic microspherules in the same horizon, and the abundance of the former is obviously higher than that of the latter. Laser Raman spectral studies show close similarities in spectral patterns between the outer shells of phosphatic microspherules and the blade of the conodont genus Palmatolepis sp., as well as between the microspherule nucleus and the platform of the same conodont genus. Furthermore, the statistical results and geochemical data demonstrate that the elevated abundance of phosphatic microspherules roughly coincides with the blooms of bacteria and algae, but is later than the sharp increase of oceanic nutrients. The phosphatic microspherules are inter- preted here to be the ＇otoliths＇ secreted by conodont animals based on the compositional similarities between phosphatic mi- crospherules and conodonts and their interrelated abundances. In addition, an analogous study reveals morphological and tex- tural similarities between fish otoliths and phosphatic microspherules. The formation of phosphatic microspherules is probably related to seawater eutrophication. We speculate that the explosive growth of bacteria and algae is probably caused by the en- richment of nutrients that is most likely associated with the increase of terrestrial inputs, submarine hydrothermal activities or the upwelling anoxic bottom waters in the late Devonian, which would stimulate the conodont animals to secrete phosphatic microspherules--the ＇otoli
基金the National Natural Science Foundation of China(21173034)the Fundamental Research Funds for the Central Universities of China(wd01206)。
文摘In this paper,we designed Eu^(2+)-doped BaAlF_(5) and BaSiF_(6) downconversion nanophosphors with strong f-f transition emission to realize the quantitative detection of TNP.The surface of the as-prepared nanophosphors was modified by polyethylenimine(PEI) to increase the water solubility and to provide a pair of electrons to bind to the benzene ring in TNP,forming a Meisenheimer complex.The detection principle of TNP is based on luminescence resonance energy transfer(LRET) technology,where the PEI-functionalized BaAlF_(5):Eu^(2+) and BaSiF_(6):Eu^(2+) nanophosphors are used as energy donors and TNP is an energy acceptor.With increasing TNP concentrations,the luminescence intensity of the BaAlF5:Eu^(2+) and BaSiF6:Eu^(2+) nanophosphors at 359 nm [^(4)f_(7)(^(6)P_(7/2))→^(4)f_(7)(^(8)S_(7/2)) transition of Eu^(2+)] displays dramatic luminescent quenching.The BaAlF_(5):Eu^(2+)@PEI or BaSiF_(6):Eu^(2+)@PEI nanophosphor downconversion luminescent sensors show great sensitivity and selectivity and good linearity,and the detection limits of TNP are 0.57 and 2.82 ng/mL,respectively.
基金the financial support from the National Natural Science Foundation of China(Nos.21790372 and 21822606)Beijing Natural Science Foundation(No.JQ20041)。
文摘The complexation of pentavalent neptunium,Np(Ⅴ),with nitrate ion in an ionic liquid solution has been studied spectroscopically for the first time.The characteristic f-f transition absorption band of Np(Ⅴ)in the NIR region changes significantly upon the titration of nitrate ion into the solution,revealing strong complexation of Np(Ⅴ)with nitrate ion in the ionic liquid.Most notably,the absorption band of Np(Ⅴ)almost disappears when a sufficiently high concentration of nitrate ion is present in the solution.Such a rare optically“silent”species can be assigned to the 1:2 Np(Ⅴ)/nitrate complex with a centrosymmetric coordination environment where Np sits at the inversion center.
