China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-pro...China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-promotion effect under high-temperature conditions remains unclear.In this study,a self-built high-temperature adsorption-desorption system was used to investigate the coupled effects of temperature and coal rank on methane adsorption-desorption behavior in deep CBM.The results show that elevated temperatures significantly reduce methane adsorption capacity,with high-rank coals exhibiting greater sensitivity.Conversely,high-temperature conditions significantly enhance methane desorption and diffusion behavior,accelerating initial desorption rates,enabling rapid gas release in a short period,and thus improving desorption efficiency.The desorption volume and desorption-diffusion rate exhibited an asymmetric U-shaped variation with coal rank.By coupling the positive and negative effects of temperature and defining the desorption ratio,it was found that a 10 K increase in temperature raised the desorption ratio by 3.78%-8.05%.Finally,an effective gas content prediction model is proposed,and the key regulatory role of temperature in the resource potential and gas production characteristics of deep CBM is clarified.These findings can provide theoretical guidance for the subsequent optimization of deep CBM exploration and development strategies.展开更多
Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various...Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various N forms(NO_(3)^(-),urea,NH_(4)^(+))at anthesis was performed to measure their effects on wheat grain protein accumulation,quality formation,and the underlying mechanisms.Foliar application of three N forms showed varying effects in improving grain gluten proteins and quality traits.Under NH_(4)^(+) application,there was more post-anthesis N uptake for grain filling,with relatively strong increase in enzyme activities and gene expression associated with N metabolism in flag leaves at 8–20 days after anthesis(DAA),whereas its promotion of grain N metabolism became weaker after 20 DAA than those under NO_(3)^(-) and urea treatments.More N was remobilized from source organs to grain under treatment with foliar NO_(3)^(-) and urea.Genes controlling the synthesis of gluten protein and disulfide bonds were upregulated by NO_(3)^(-) and urea at 20–28 DAA,contributing to increased grain protein content and quality.Overall,foliar applications of NO_(3)^(-) and urea were more effective than those of NH_(4)^(+) in increasing grain N filling.These findings show that manipulating the source–sink relationship by reinforcing grain N metabolism and N remobilization is critical for optimizing grain protein accumulation and quality formation.展开更多
As an important forcing data for hydrologic models, precipitation has significant effects on model simulation. The China Meteorological Forcing Dataset （ITP） and Global Land Data Assimilation System （GLDAS） precip...As an important forcing data for hydrologic models, precipitation has significant effects on model simulation. The China Meteorological Forcing Dataset （ITP） and Global Land Data Assimilation System （GLDAS） precipitation data are the two commonly used data sources in the Heihe River Basin （HRB）. This paper focused on evaluating the accuracy of these two precipitation datasets. A set of metrics were developed to characterize the trend, magnitude, annual allocation, event matching, frequency, and spatial distribution of the two datasets. Meanwhile, such accuracy evaluation was performed at various scales, i.e., daily, monthly, and yearly. By comparing with observations, this study concluded that： first, both ITP and GLDAS precipitation data well represented the trends at corresponding sites, and GLDAS underestimated precipita- tion in most regions except the east tributary headwater region; second, unusual annual precipitation distribution was observed in both datasets with overestimation of precipitation in May through September and GLDAS appeared to be much severe; third, the ITP data seriously over-predicted the precipitation events; fourth, the ITP data have better spatial distribution than GLDAS in the upper reach area of HRB. Overall, we recommended ITP precipitation data for the land surface study in the uooer reach of HRB.展开更多
Both batch-to-batch(B2 B)and roll-to-roll(R2 R)processes can be used for mass production of graphene films.Because of the simplicity of equipment,the B2 B process is more commonly used in laboratory research.In contra...Both batch-to-batch(B2 B)and roll-to-roll(R2 R)processes can be used for mass production of graphene films.Because of the simplicity of equipment,the B2 B process is more commonly used in laboratory research.In contrast,the R2 R process is more industrially preferred because it is easier to automate and more compatible with the subsequent transfer process.Up to now,the research on R2 R process has mainly focused on the design of the reactor or the loading configuration,but the in-depth understanding on the growth kinetics is lack.In this paper,we investigated the evolution of graphene growth and revealed that the graphene domain density grown by the R2 R process was larger than that by the B2 B process with the same reaction parameters,which was attributed to different reaction profiles between the two processes.Furthermore,the defective graphene could be healed with elongated reaction time.With the optimized R2 R process,graphene films with quality comparable to those grown by conventional B2 B process could be achieved.Our research will promote the development of the mass-production technique for graphene films.展开更多
Chemical vapor deposition(CVD)is the most promising method for the preparation of high-quality and large-area graphene films,especially the epitaxial growth of graphene on large-area single-crystal Cu foils.While sing...Chemical vapor deposition(CVD)is the most promising method for the preparation of high-quality and large-area graphene films,especially the epitaxial growth of graphene on large-area single-crystal Cu foils.While single-crystal Cu foils are normally achieved by thermally annealing the commercial poly-crystalline Cu foils,their size and therefore the size of graphene films grown on them are limited to the size of the reaction chamber.We report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils,where the Cu layers are separated by thin porous carbon fiber cloths.The carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas transportation.In such a way,the utilization efficiency of the reaction chamber is significantly improved,e.g.,0.2 m×(1e2)m Cu foils can be processed even in a 5 cm diameter quartz tube chamber.High-quality graphene films grown on such Cu foils are then demon-strated.This method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.展开更多
基金supported by the National Natural Science Fund of China(No.42272195)the National Natural Science Fund of China(No.42130802)+2 种基金the Fundamental Research Funds for the Central Universities(No.2025ZDPY10)the China National Petroleum Co.,Ltd..Research applied science and technology special(No.2023ZZ18)the PetroChina Changqing oilfield science and technology major project(No.2023DZZ01).
文摘China’s deep coalbed methane(CBM)resources demonstrate immense potential with extensive developmental prospects.However,the coupling relationship between the negative adsorption effect and the positive desorption-promotion effect under high-temperature conditions remains unclear.In this study,a self-built high-temperature adsorption-desorption system was used to investigate the coupled effects of temperature and coal rank on methane adsorption-desorption behavior in deep CBM.The results show that elevated temperatures significantly reduce methane adsorption capacity,with high-rank coals exhibiting greater sensitivity.Conversely,high-temperature conditions significantly enhance methane desorption and diffusion behavior,accelerating initial desorption rates,enabling rapid gas release in a short period,and thus improving desorption efficiency.The desorption volume and desorption-diffusion rate exhibited an asymmetric U-shaped variation with coal rank.By coupling the positive and negative effects of temperature and defining the desorption ratio,it was found that a 10 K increase in temperature raised the desorption ratio by 3.78%-8.05%.Finally,an effective gas content prediction model is proposed,and the key regulatory role of temperature in the resource potential and gas production characteristics of deep CBM is clarified.These findings can provide theoretical guidance for the subsequent optimization of deep CBM exploration and development strategies.
基金supported by the National Natural Science Foundation of China(31971860).
文摘Foliar nitrogen(N)application is an effective strategy to improve protein content and quality in wheat kernels,but the specific effects of N forms remain unclear.In a two-year field study,foliar application of various N forms(NO_(3)^(-),urea,NH_(4)^(+))at anthesis was performed to measure their effects on wheat grain protein accumulation,quality formation,and the underlying mechanisms.Foliar application of three N forms showed varying effects in improving grain gluten proteins and quality traits.Under NH_(4)^(+) application,there was more post-anthesis N uptake for grain filling,with relatively strong increase in enzyme activities and gene expression associated with N metabolism in flag leaves at 8–20 days after anthesis(DAA),whereas its promotion of grain N metabolism became weaker after 20 DAA than those under NO_(3)^(-) and urea treatments.More N was remobilized from source organs to grain under treatment with foliar NO_(3)^(-) and urea.Genes controlling the synthesis of gluten protein and disulfide bonds were upregulated by NO_(3)^(-) and urea at 20–28 DAA,contributing to increased grain protein content and quality.Overall,foliar applications of NO_(3)^(-) and urea were more effective than those of NH_(4)^(+) in increasing grain N filling.These findings show that manipulating the source–sink relationship by reinforcing grain N metabolism and N remobilization is critical for optimizing grain protein accumulation and quality formation.
基金supported by NSFC (91125006)partially by state key laboratory grant (SKLFSE201009)
文摘As an important forcing data for hydrologic models, precipitation has significant effects on model simulation. The China Meteorological Forcing Dataset （ITP） and Global Land Data Assimilation System （GLDAS） precipitation data are the two commonly used data sources in the Heihe River Basin （HRB）. This paper focused on evaluating the accuracy of these two precipitation datasets. A set of metrics were developed to characterize the trend, magnitude, annual allocation, event matching, frequency, and spatial distribution of the two datasets. Meanwhile, such accuracy evaluation was performed at various scales, i.e., daily, monthly, and yearly. By comparing with observations, this study concluded that： first, both ITP and GLDAS precipitation data well represented the trends at corresponding sites, and GLDAS underestimated precipita- tion in most regions except the east tributary headwater region; second, unusual annual precipitation distribution was observed in both datasets with overestimation of precipitation in May through September and GLDAS appeared to be much severe; third, the ITP data seriously over-predicted the precipitation events; fourth, the ITP data have better spatial distribution than GLDAS in the upper reach area of HRB. Overall, we recommended ITP precipitation data for the land surface study in the uooer reach of HRB.
基金supported by the National Natural Science Foundation of China(51772043,51802036)Shenzhen Science and Technology Program((2021)105)。
文摘Both batch-to-batch(B2 B)and roll-to-roll(R2 R)processes can be used for mass production of graphene films.Because of the simplicity of equipment,the B2 B process is more commonly used in laboratory research.In contrast,the R2 R process is more industrially preferred because it is easier to automate and more compatible with the subsequent transfer process.Up to now,the research on R2 R process has mainly focused on the design of the reactor or the loading configuration,but the in-depth understanding on the growth kinetics is lack.In this paper,we investigated the evolution of graphene growth and revealed that the graphene domain density grown by the R2 R process was larger than that by the B2 B process with the same reaction parameters,which was attributed to different reaction profiles between the two processes.Furthermore,the defective graphene could be healed with elongated reaction time.With the optimized R2 R process,graphene films with quality comparable to those grown by conventional B2 B process could be achieved.Our research will promote the development of the mass-production technique for graphene films.
基金supported by National Natural Science Founda-tion of China(No.52172138)Shenzhen Science and Technology Program(No.(2021)105).
文摘Chemical vapor deposition(CVD)is the most promising method for the preparation of high-quality and large-area graphene films,especially the epitaxial growth of graphene on large-area single-crystal Cu foils.While single-crystal Cu foils are normally achieved by thermally annealing the commercial poly-crystalline Cu foils,their size and therefore the size of graphene films grown on them are limited to the size of the reaction chamber.We report a simple and feasible method to prepare large-area Cu foils with decimeter grains by thermally annealing the rolled-up Cu foils,where the Cu layers are separated by thin porous carbon fiber cloths.The carbon fiber cloths prevent Cu layers from sticking to each other at high temperatures while do not block the gas transportation.In such a way,the utilization efficiency of the reaction chamber is significantly improved,e.g.,0.2 m×(1e2)m Cu foils can be processed even in a 5 cm diameter quartz tube chamber.High-quality graphene films grown on such Cu foils are then demon-strated.This method may be suitable for the annealing of other metal foils to enlarge grain size and the synthesis of other two-dimensional materials on them such as h-BN.
