Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal （RE, with lanthanum and cerium） doped WC-8%Co-0.048%RE（ma...Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal （RE, with lanthanum and cerium） doped WC-8%Co-0.048%RE（mass fraction） alloy with low carbon-containing level by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）, considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin （surface） is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.展开更多
Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration （DPDM） is based on accurate elevations of sources and receivers, by whi...Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration （DPDM） is based on accurate elevations of sources and receivers, by which static correction is completely abandoned before migration and surely the imaging quality is remarkably improved. To obtain some artificial shot gathers, high-order staggered-grid finite-difference （FD） method is adapted to model acoustic wave propagation. Since the shot gathers are always disturbed by regular interferences, the statics still must be applied to supporting the interference elimination by apparent velocity filtering method. Then all the shot gathers should be removed back to their original positions by reverse statics. Finally, they are migrated by pre-stack reverse-time depth migration and imaged. The numerical experiments show that the DPDM can ideally avoid the mistakes caused by statics and increase imaging precision.展开更多
Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been in...Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been independently demonstrated.However,how cells respond to electromechanical coupling cues remains mysterious.In this study,an electro-stiffness-coupled chip system was designed and fabricated,freely integrating and precisely controlling EF strength and the mechanical stiffness applied to cells across the physiological spectrum.Utilizing the innovative bioreactor,it was observed that electromechanical coupling stimulations can shape cancer cell morphology and cytoskeleton into a unique anteroposterior polarization state and orient cancer cell migration in a voltage-dependent manner through cytoskeleton-associated mechanisms.Moreover,the mechanical stiffness regulated cancer cell susceptibility to EFs,and the orientation effect of EFs on cells required a stiffness threshold.Furthermore,transforming growth factor-β1 suppressed the orientation of cancer cells induced by electromechanical coupling signals and showed a splitting effect on the directionality and velocity of cancer cell migration,indicating a comprehensive cross-talk of biochemical–electromechanical signals.Together with the dual-physical bioreactor we designed,these findings provide a robust and convenient platform for exploring cellular responses to electro-stiffness coupling signals,reveal the biophysical mechanisms of cell polarization and migration from the perspective of electromechanical coupling,and lay a promising foundation for biophysical-based cell manipulation and therapeutic interventions.展开更多
The Upper Permian Changxing dolomite reservoirs serves as one of the most important gas and oil reservoirs in the NE Sichuan Basin. Determining the dolomitizing fluid＇s pathway is regarded as the key to solve the ＂d...The Upper Permian Changxing dolomite reservoirs serves as one of the most important gas and oil reservoirs in the NE Sichuan Basin. Determining the dolomitizing fluid＇s pathway is regarded as the key to solve the ＂dolomite problem＂ and further petroleum exploration. Outcrop samples from Upper Permian Changhsingian Panlongdong Section were studied using oxygen isotopic analysis, cathodoluminescence（CL） and major element analysis, in an attempt to determine the migration path way and properties of the dolomitizing fluid. Of the Changxing dolomite, the δ18O values ranged from-3.494‰ to-5.481‰, which decreased from the top layer to the bottom in the section; the MgO contents varied from 9.24% to 21.43%, CaO contents from 28.65% to 39.87%, the CaO/MgO ratio from 1.40 to 4.31 and the Mn O contents from 0.004% to 0.009 8%. The Mg O contents showed a downwardly decreasing trend in the section, while the Ca O/Mg O showed an opposite rule. All of the dolomites looked dull or dark when they were exposed to the electron beam of the cathodoluminescence device. None of the fine-to medium grained dolomite showed a banded structure. Given that dolomitizing fluid＇s salinity decreased during the dolomitization process in its pathway, we concluded that the dolomitizing fluid migrated downwardly in Changxing Formation after excluding the possibility of deep burial or meteoric-marine mixing-water influences. As the dolomitizing fluid＇s pathway has always been difficult to be determined in highly dolomitized Formation, this study showed an important application of oxygen isotope values in resolving this problem.展开更多
A promising therapeutic strategy to promote the regeneration of injured axons in the adult central nervous system（CNS）is the transplantation of cells or tissues that can modify the local host environment and support...A promising therapeutic strategy to promote the regeneration of injured axons in the adult central nervous system（CNS）is the transplantation of cells or tissues that can modify the local host environment and support the growth of regenerating axons.展开更多
The efficient utilization of visible light catalysts for organic reactions necessitates not only the effective separation of photogenerated electrons and holes to participate in the reaction,but also their ability to ...The efficient utilization of visible light catalysts for organic reactions necessitates not only the effective separation of photogenerated electrons and holes to participate in the reaction,but also their ability to form key intermediates with reactant molecules.The present study successfully synthesized a crusiform-like mesoporous structure of nitrogen-doped carbon-coated Cu_(2)O/Cu(Cu_(2)O/Cu/N-C)with a Cu_(2)O/dual electron acceptor interface using etched HKUST-1 as the precursor.A series of theoretical and experimental studies have demonstrated that the Cu_(2)O/Cu/N-C interface in the photocatalytic homo-coupling of terminal alkynes not only effectively enhances the separation of photogenerated electron−hole pairs,but also facilitates the formation of the key intermediate[Cu_(2)O/Cu/N-C]-phenylacetylide and promotes the rearrangement of its internal charges.As a result,the homo-coupling reaction can be effectively facilitated.The primary reason for the functional role of Cu_(2)O/Cu/N-C interface lies in the downward bending of energy band from Cu_(2)O to N-doped C layers,induced by the different work functions of Cu_(2)O,Cu and N-doped C layers.Consequently,Cu_(2)O/Cu/N-C photocatalysts demonstrate exceptional photocatalytic activity in the homo-coupling reaction of terminal alkynes under blue-light irradiation and air atmosphere.The present study presents a novel research methodology for the development of highly efficient visible light catalysts to facilitate organic reactions in future applications.展开更多
Thermocapillary migration in lubrication systems is a phenomenon in which the lubricant migrates via the interfacial tension difference caused by the nonuniform temperature generated by the wear behavior,which leads t...Thermocapillary migration in lubrication systems is a phenomenon in which the lubricant migrates via the interfacial tension difference caused by the nonuniform temperature generated by the wear behavior,which leads to lubricant starvation and results in severe damage.This paper proposes a novel method to eliminate the thermocapillary migration phenomenon,in which we successfully fabricate a surface that combines a shape gradient and wettability pattern on 316 L stainless steel,and the results prove that the prepared surface can not only effectively obstruct liquid paraffin droplet migration but also directionally transport liquid paraffin to the center of the wear track under the thermocapillary migration effect.The results of the wear tests further demonstrated that only the surface combination of a shape gradient and wettability pattern can achieve a decrease in the friction coefficient by means of external lubricant feeding in the state of lubricant starvation,which provides a strategy for improving and developing new types of lubrication enhancement for mitigating starvation lubrication.展开更多
The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE repres...The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, andβis cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.展开更多
The Markit Slope is an important area for the petroleum exploration in the Tarim Basin. Elucidation of the oil filling history of discovered oilfields has great significance for recognizing the accumulation processes ...The Markit Slope is an important area for the petroleum exploration in the Tarim Basin. Elucidation of the oil filling history of discovered oilfields has great significance for recognizing the accumulation processes of the whole region. Using molecular geochemistry, fluid inclusion techniques and basin modeling, we studied the oil filling process of the Bashituo Oilfield that is located in the west of the Markit Slope. The molecular migration indexes, such as the methyldibenzothiophene ratio （4-/1-MDBT）, trimethylnaphthalene ratio （TMNr） and pyrrolic nitrogen compounds content, decrease from west to east, indicating that the charging direction and migration pathways are from west to east. Lithological analysis and homogenization temperatures of saline fluid inclusions accompanied with oil fluid inclusions suggest that two charging periods occurred in the Devonian oil reservoir. Combining the burial history and heating history of well BT4, Basinmod 1D software modeling shows the two oil filling periods are from 290 Ma to 285 Ma and from l0 Ma to 4 Ma, respectively, and later oil filling dominates. This study may be helpful to understand the accumulation process and provide useful references for oil and gas exploration in the Markit Slope.展开更多
In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were a...In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.展开更多
Animal and clinical studies have confirmed the therapeutic effect of bone marrow mesenchymal stem cells on cerebral ischemia, but their mechanisms of action remain poorly understood. Here, we summarize the transplanta...Animal and clinical studies have confirmed the therapeutic effect of bone marrow mesenchymal stem cells on cerebral ischemia, but their mechanisms of action remain poorly understood. Here, we summarize the transplantation approaches, directional migration, differentiation, replacement, neural circuit reconstruction,angiogenesis, neurotrophic factor secretion, apoptosis, immunomodulation, multiple mechanisms of action,and optimization strategies for bone marrow mesenchymal stem cells in the treatment of ischemic stroke.We also explore the safety of bone marrow mesenchymal stem cell transplantation and conclude that bone marrow mesenchymal stem cell transplantation is an important direction for future treatment of cerebral ischemia. Determining the optimal timing and dose for the transplantation are important directions for future research.展开更多
The random mobility of charge carriers is a main factor causing the low photocatalytic efficiency of gCN.Thus,the controllable migration of charge carriers is a rational strategy to suppress the charge recombination a...The random mobility of charge carriers is a main factor causing the low photocatalytic efficiency of gCN.Thus,the controllable migration of charge carriers is a rational strategy to suppress the charge recombination and facilitate charge separation.Herein,an ethylenediamine modified g-C_(3)N_(4)displays improved photocatalytic activity.The excellent charge separation efficiency is confirmed to be a key factor for the enhancement.The TEM observation after photo-depositing Pt nanoparticles and DFT calculations verify the accumulation of electrons on some areas of g-C_(3)N_(4)surface.The increased-NH_(2)groups significantly tune the electronic structure of g-C_(3)N_(4)after the modification.The generation of midgap states also affects the charge separation.Our reports provide a simple method to manage the migration of charge carriers and enable electrons directional transfer,which suppresses the recombination and improves the photocatalytic activity.展开更多
The period around Chinese New Year is the most active period of national popula-tion movement in China,providing a natural experiment to examine the character-istics of population flow and interregional connections.Ba...The period around Chinese New Year is the most active period of national popula-tion movement in China,providing a natural experiment to examine the character-istics of population flow and interregional connections.Based on Baidu migration big data from the 2022 and 2023 Spring Festival travel rush,this study analyses over 2.7 billion population flow records from 293 prefecture-level cities and 4 munici-palities over 80 days.From the perspectives of external connections and concentra-tion levels,this study investigates the characteristics and agglomeration features of population mobility at the provincial level.This study reveals that the average daily passenger flow during the 2023 Spring Festival travel rush significantly increased compared to 2022,and the proportion of interprovincial population flow in each province also increased,indicating a rebound in the scale and openness of popula-tion mobility after the COVID-19 pandemic.Guangdong Province is the most active in terms of population mobility,attracting both domestic and out-of-province popu-lations.Provinces with active interprovincial migration are mainly concentrated in the central and eastern regions,with all provinces in the Yangtze River Delta being major employment hubs.Interprovincial migrant populations not only have a large scale and high proportion but also diverse source regions.Central provinces such as Henan,Anhui,and Hunan are major labour exporters.Western,North,and North-east China mainly experience intraprovincial population flow,with interprovincial mobility mostly occurring within provinces in the same region.In contrast,border provinces such as Xinjiang and Tibet have smaller population flows,are less attrac-tive for populations from other provinces,and have lower proportions of local popu-lations leaving,indicating a need for enhanced external connections.展开更多
基金Project(50574104) supported by the National Natural Science Foundation of China
文摘Three observation methods were used to investigate the existing form and the behavior of rare earth during the sintering process of high activity mischmetal （RE, with lanthanum and cerium） doped WC-8%Co-0.048%RE（mass fraction） alloy with low carbon-containing level by scanning electron microscopy （SEM） and energy dispersive X-ray spectroscopy （EDXS）, considering the fact that the addition amount of rare earth in the alloy is very minute. The directional migration process and mechanism of cerium were discussed. First, the sinter skin （surface） is observed. oxide on the sinter skin, and lanthanum in these cerium observed, and lanthanum containing phase/micro-zone in It is shown that there exists a dispersedly distributed cerium containing enrichment positions is very minute. Secondly, the polished section is the alloy is identified. Finally, based on the fact that the fracture of cemented carbide is resulted from the heterogeneous phase or other defects within the microstructure, the fracture surface is observed and cerium containing phase/micro-zone in the fracture source approximately 260 μm from the surface is identified. These combined observations reveal adequately the fact that lanthanum and cerium get separated and cerium predominantly migrates towards the surface during the sintering process.
文摘Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration （DPDM） is based on accurate elevations of sources and receivers, by which static correction is completely abandoned before migration and surely the imaging quality is remarkably improved. To obtain some artificial shot gathers, high-order staggered-grid finite-difference （FD） method is adapted to model acoustic wave propagation. Since the shot gathers are always disturbed by regular interferences, the statics still must be applied to supporting the interference elimination by apparent velocity filtering method. Then all the shot gathers should be removed back to their original positions by reverse statics. Finally, they are migrated by pre-stack reverse-time depth migration and imaged. The numerical experiments show that the DPDM can ideally avoid the mistakes caused by statics and increase imaging precision.
基金Beijing Academy of Science and Technology (BJAST) supported this worksupported by the Financial Program of BJAST (Nos. 24CE-BGS-02, 24CA010-01, and 23CB106)
文摘Cells live in a multiphysics-coupled microenvironment in vivo,in which electric fields(EFs)and mechanical cues are the most essential induction signals.The regulatory effects of EFs and stiffness on cells have been independently demonstrated.However,how cells respond to electromechanical coupling cues remains mysterious.In this study,an electro-stiffness-coupled chip system was designed and fabricated,freely integrating and precisely controlling EF strength and the mechanical stiffness applied to cells across the physiological spectrum.Utilizing the innovative bioreactor,it was observed that electromechanical coupling stimulations can shape cancer cell morphology and cytoskeleton into a unique anteroposterior polarization state and orient cancer cell migration in a voltage-dependent manner through cytoskeleton-associated mechanisms.Moreover,the mechanical stiffness regulated cancer cell susceptibility to EFs,and the orientation effect of EFs on cells required a stiffness threshold.Furthermore,transforming growth factor-β1 suppressed the orientation of cancer cells induced by electromechanical coupling signals and showed a splitting effect on the directionality and velocity of cancer cell migration,indicating a comprehensive cross-talk of biochemical–electromechanical signals.Together with the dual-physical bioreactor we designed,these findings provide a robust and convenient platform for exploring cellular responses to electro-stiffness coupling signals,reveal the biophysical mechanisms of cell polarization and migration from the perspective of electromechanical coupling,and lay a promising foundation for biophysical-based cell manipulation and therapeutic interventions.
基金supported by the National Natural Science Foundation of China (Nos.40472015, 40802001, and 41372121)the State Key Laboratory of Oil/Gas Reservoir Geology and Exploitation at CDUT (PL200801)
文摘The Upper Permian Changxing dolomite reservoirs serves as one of the most important gas and oil reservoirs in the NE Sichuan Basin. Determining the dolomitizing fluid＇s pathway is regarded as the key to solve the ＂dolomite problem＂ and further petroleum exploration. Outcrop samples from Upper Permian Changhsingian Panlongdong Section were studied using oxygen isotopic analysis, cathodoluminescence（CL） and major element analysis, in an attempt to determine the migration path way and properties of the dolomitizing fluid. Of the Changxing dolomite, the δ18O values ranged from-3.494‰ to-5.481‰, which decreased from the top layer to the bottom in the section; the MgO contents varied from 9.24% to 21.43%, CaO contents from 28.65% to 39.87%, the CaO/MgO ratio from 1.40 to 4.31 and the Mn O contents from 0.004% to 0.009 8%. The Mg O contents showed a downwardly decreasing trend in the section, while the Ca O/Mg O showed an opposite rule. All of the dolomites looked dull or dark when they were exposed to the electron beam of the cathodoluminescence device. None of the fine-to medium grained dolomite showed a banded structure. Given that dolomitizing fluid＇s salinity decreased during the dolomitization process in its pathway, we concluded that the dolomitizing fluid migrated downwardly in Changxing Formation after excluding the possibility of deep burial or meteoric-marine mixing-water influences. As the dolomitizing fluid＇s pathway has always been difficult to be determined in highly dolomitized Formation, this study showed an important application of oxygen isotope values in resolving this problem.
基金supported by NIH NS055976Craig H.Neilsen Foundation 280850
文摘A promising therapeutic strategy to promote the regeneration of injured axons in the adult central nervous system（CNS）is the transplantation of cells or tissues that can modify the local host environment and support the growth of regenerating axons.
基金supported by the Xuzhou Key Research and Development Program(Social Development)(No.KC23298)the National Natural Science Foundation of China(No.22271122)+1 种基金the Natural Science Foundation of Jiangsu Province(No.BK20211549)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX23_2903).
文摘The efficient utilization of visible light catalysts for organic reactions necessitates not only the effective separation of photogenerated electrons and holes to participate in the reaction,but also their ability to form key intermediates with reactant molecules.The present study successfully synthesized a crusiform-like mesoporous structure of nitrogen-doped carbon-coated Cu_(2)O/Cu(Cu_(2)O/Cu/N-C)with a Cu_(2)O/dual electron acceptor interface using etched HKUST-1 as the precursor.A series of theoretical and experimental studies have demonstrated that the Cu_(2)O/Cu/N-C interface in the photocatalytic homo-coupling of terminal alkynes not only effectively enhances the separation of photogenerated electron−hole pairs,but also facilitates the formation of the key intermediate[Cu_(2)O/Cu/N-C]-phenylacetylide and promotes the rearrangement of its internal charges.As a result,the homo-coupling reaction can be effectively facilitated.The primary reason for the functional role of Cu_(2)O/Cu/N-C interface lies in the downward bending of energy band from Cu_(2)O to N-doped C layers,induced by the different work functions of Cu_(2)O,Cu and N-doped C layers.Consequently,Cu_(2)O/Cu/N-C photocatalysts demonstrate exceptional photocatalytic activity in the homo-coupling reaction of terminal alkynes under blue-light irradiation and air atmosphere.The present study presents a novel research methodology for the development of highly efficient visible light catalysts to facilitate organic reactions in future applications.
基金supported by the National Natural Science Foundation of China(No.52205204)the Outstanding Youth Innovation Team in Universities of Shandong Province(No.2023KJ116).
文摘Thermocapillary migration in lubrication systems is a phenomenon in which the lubricant migrates via the interfacial tension difference caused by the nonuniform temperature generated by the wear behavior,which leads to lubricant starvation and results in severe damage.This paper proposes a novel method to eliminate the thermocapillary migration phenomenon,in which we successfully fabricate a surface that combines a shape gradient and wettability pattern on 316 L stainless steel,and the results prove that the prepared surface can not only effectively obstruct liquid paraffin droplet migration but also directionally transport liquid paraffin to the center of the wear track under the thermocapillary migration effect.The results of the wear tests further demonstrated that only the surface combination of a shape gradient and wettability pattern can achieve a decrease in the friction coefficient by means of external lubricant feeding in the state of lubricant starvation,which provides a strategy for improving and developing new types of lubrication enhancement for mitigating starvation lubrication.
基金Project(51074189)supported by the National Natural Science Foundation of ChinaProject(2012ZX04003–021)supported by the National Science&Technology Special Foundation of ChinaProject(Y2012–010)supported by the Nonferrous Metals Research Foundation from Hunan Nonferrous Metals Holding Group Co.,Ltd.–CSU,China
文摘The as-sintered sinter skin of WC-11Co-0.71Cr3C2-0.06RE cemented carbide with WC＋βmicrostructure was analyzed by scanning electron microscope, energy dispersive X-ray spectroscope and X-ray diffractometer. RE represents La-, Ce-, Pr- and Nd-containing mischmetal, andβis cobalt-based binder phase. It was discovered that La, Ce, Pr and Nd migrated directionally from the alloy to the sinter skin to combine with the impurity elements S and O from the sintering atmosphere during the sintering process. As a result, main dispersed phase RE2S3 and minor RE2O2S were formed in situ on the sinter skin. The mechanisms for the stimulation of the migration activity and the directional migration of RE atoms were discussed in terms of the thermodynamics stability of Cr3C2, solubility characteristic of Cr in Co and the polarization or ionization of RE atoms.
基金supported by the Natural Science Foundation of China (Grant No.40972089)the Foundation of the State Key Laboratory of Petroleum Resources and Prospecting (Grant No.PRPDX2008-01)
文摘The Markit Slope is an important area for the petroleum exploration in the Tarim Basin. Elucidation of the oil filling history of discovered oilfields has great significance for recognizing the accumulation processes of the whole region. Using molecular geochemistry, fluid inclusion techniques and basin modeling, we studied the oil filling process of the Bashituo Oilfield that is located in the west of the Markit Slope. The molecular migration indexes, such as the methyldibenzothiophene ratio （4-/1-MDBT）, trimethylnaphthalene ratio （TMNr） and pyrrolic nitrogen compounds content, decrease from west to east, indicating that the charging direction and migration pathways are from west to east. Lithological analysis and homogenization temperatures of saline fluid inclusions accompanied with oil fluid inclusions suggest that two charging periods occurred in the Devonian oil reservoir. Combining the burial history and heating history of well BT4, Basinmod 1D software modeling shows the two oil filling periods are from 290 Ma to 285 Ma and from l0 Ma to 4 Ma, respectively, and later oil filling dominates. This study may be helpful to understand the accumulation process and provide useful references for oil and gas exploration in the Markit Slope.
基金supported by NSFC (Grant No. 41202100)the National Science and Technology Major Projects(Grant No. 2008ZX05007-003)
文摘In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.
基金supported by the Natural Science Foundation of Heilongjiang Province of China,No.H2015083a grant from Higher Education Reform Project of Mudanjaing Medical University of China,No.2013016
文摘Animal and clinical studies have confirmed the therapeutic effect of bone marrow mesenchymal stem cells on cerebral ischemia, but their mechanisms of action remain poorly understood. Here, we summarize the transplantation approaches, directional migration, differentiation, replacement, neural circuit reconstruction,angiogenesis, neurotrophic factor secretion, apoptosis, immunomodulation, multiple mechanisms of action,and optimization strategies for bone marrow mesenchymal stem cells in the treatment of ischemic stroke.We also explore the safety of bone marrow mesenchymal stem cell transplantation and conclude that bone marrow mesenchymal stem cell transplantation is an important direction for future treatment of cerebral ischemia. Determining the optimal timing and dose for the transplantation are important directions for future research.
基金supported by Shenzhen Key Laboratory of Solid State Batteries(ZDSYS20180208184346531)Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(2018B030322001)+3 种基金Guangdong Provincial Key Laboratory of Catalysis(2020B121201002)Shenzhen Clean Energy Research Institute(CERI-KY-2019-003)the National Natural Science Foundation of China(2017M611446)supported by the Core Research Facilities at SUSTech that receives support from a Presidential fund and the Development and Reform Commission of Shenzhen Municipality。
文摘The random mobility of charge carriers is a main factor causing the low photocatalytic efficiency of gCN.Thus,the controllable migration of charge carriers is a rational strategy to suppress the charge recombination and facilitate charge separation.Herein,an ethylenediamine modified g-C_(3)N_(4)displays improved photocatalytic activity.The excellent charge separation efficiency is confirmed to be a key factor for the enhancement.The TEM observation after photo-depositing Pt nanoparticles and DFT calculations verify the accumulation of electrons on some areas of g-C_(3)N_(4)surface.The increased-NH_(2)groups significantly tune the electronic structure of g-C_(3)N_(4)after the modification.The generation of midgap states also affects the charge separation.Our reports provide a simple method to manage the migration of charge carriers and enable electrons directional transfer,which suppresses the recombination and improves the photocatalytic activity.
基金Major Program of National Fund of Philosophy and Social Science of China:Research on Precision Management of Public Services Driven by Big Data(Project No.:20&ZD113).
文摘The period around Chinese New Year is the most active period of national popula-tion movement in China,providing a natural experiment to examine the character-istics of population flow and interregional connections.Based on Baidu migration big data from the 2022 and 2023 Spring Festival travel rush,this study analyses over 2.7 billion population flow records from 293 prefecture-level cities and 4 munici-palities over 80 days.From the perspectives of external connections and concentra-tion levels,this study investigates the characteristics and agglomeration features of population mobility at the provincial level.This study reveals that the average daily passenger flow during the 2023 Spring Festival travel rush significantly increased compared to 2022,and the proportion of interprovincial population flow in each province also increased,indicating a rebound in the scale and openness of popula-tion mobility after the COVID-19 pandemic.Guangdong Province is the most active in terms of population mobility,attracting both domestic and out-of-province popu-lations.Provinces with active interprovincial migration are mainly concentrated in the central and eastern regions,with all provinces in the Yangtze River Delta being major employment hubs.Interprovincial migrant populations not only have a large scale and high proportion but also diverse source regions.Central provinces such as Henan,Anhui,and Hunan are major labour exporters.Western,North,and North-east China mainly experience intraprovincial population flow,with interprovincial mobility mostly occurring within provinces in the same region.In contrast,border provinces such as Xinjiang and Tibet have smaller population flows,are less attrac-tive for populations from other provinces,and have lower proportions of local popu-lations leaving,indicating a need for enhanced external connections.
