Background Although the first leading cause of death in China was malignant neoplasms （mortality, 374.1 per 100 000 person-years）, the full impact of primary brain tumors （PBT） on the healthcare system is not comp...Background Although the first leading cause of death in China was malignant neoplasms （mortality, 374.1 per 100 000 person-years）, the full impact of primary brain tumors （PBT） on the healthcare system is not completely described because there are a few well documented reports about the epidemiologic features of brain tumors. This study aimed to report a comprehensive assessment on the prevalence of PBT. Methods A multicenter cross-sectional study on brain tumor （MCSBT） in China was initiated in five regional centers： Daqing （northeast）, Puyang （north of China）, Shiyan （center of China）, Ma＇anshan （center of China） and Shanghai （southeast）. Prevalence rate was calculated by counting the number of people living with a PBT between October 1,2005 and September 30, 2006 and dividing by the total population of the five communities at January 1, 2006. Estimates of prevalence were expressed as percentages and grouped according to gender and to age in fifteen-year categories. Within these strata, the rates were estimated with 95% confidence intervals （C/） using the accurate calculation of CI for Poisson distribution. A chi-square test was used to compare the various frequencies with a 〈0.05. Age-standardized prevalence with the direct method was calculated with the ten-year age-specific prevalence and the age distribution of population prospects： the 2008 revision. Results We estimated that the overall prevalence of PBT was 24.56 per 100 000 （95% CI, 14.85 to 34.27）, and the overall prevalence of PBT in female population （30.57 per 100 000 and its 95% Cl ranged from 19.73 to 41.41） was higher than that in male population （18.84 per 100 000 and its 95% Cl ranged from 10.33 to 27.35）. However, the discrepancy between genders was not statistically significant because the 95% Cl overlapped. Of 272 cases of newly diagnosed PBT, the proportion of histological subtypes by age groups, gender was statistically different （X2=52.6510, P 〈0.0001）. More than half of all re展开更多
There are three types of shale gas resources in China.The resources are present in large amounts and are widely distributed.Marine facies,transitional facies and continental facies resources each account for a third.B...There are three types of shale gas resources in China.The resources are present in large amounts and are widely distributed.Marine facies,transitional facies and continental facies resources each account for a third.Based on resource distributions,there are many wells penetrated into the Sinian,Cambrian, Ordovieian,Silurian,Devonian,Carboniferous and Permian strata of the Yangtze plate and its periphery, the North China Craton and the Tarim Basin.Many years of exploration have indicated that the marine Silurian Longmaxi shale gas is widely distributed in south China and has been industrialized in its production in the Siehuan basin.The shale gas from the Cambrian Niutitang Formation and the Sinian Doushantuo Formation are important discoveries in Yichang,Hub ei and Zhenba,Shanxi.There are also shale gas resources found within transitional facies and continental facies in different areas in China.The "two element enrichment theory"has been summarized during the exploration process of Silurian marine shale gas in the Sichuan Basin.In addition,horizontal drilling and fracturing technologies up to 3500 m in depth have been developed.Based on the understanding of shale gas accumulation in a complex tectonic zone outside the Sichnan basin,a preliminary summary of the formation of the "converse fault syneline control reservoir"and "paleo uplift control reservoir"model has been constructed.The dominant theory of "Trinity"shale gas enrichment and the high yield of the "deep water Lu Pengxiang sedimentary facies belt, structural preservation conditions and overpressure"is summarized.Guided by the above theories.Anyel well in Guizhou and Eyangyel well in Hubei were drilled."Four storey"oil and shale "gas is found in the Permian Qixia group,the Silurian Shiniulan Formation,the Longmaxi Formation and the Ordovician Baota Formation in Anyel well.Good shale gas has been gound in the Cambrian Niutitang formation inian Doushantuo formation in Eyangye lwell.This paper aims to summarize and review the main progress,theoretical tech展开更多
Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since ...Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.展开更多
Hard carbon is the most promising anode for sodium-ion battery applications due to the wide availability and low work voltage.However,it often delivers worse electrochemical performance in ester-based electrolytes.Her...Hard carbon is the most promising anode for sodium-ion battery applications due to the wide availability and low work voltage.However,it often delivers worse electrochemical performance in ester-based electrolytes.Herein,a hierarchically porous loose sponge-like hard carbon with a highly disordered phase,prepared from the biomass of platanus bark,exhibits superior rate performance with a capacity of 165 mAh·g-1 at a high current of1 A·g-1,and high retention of 71.5%after 2000 cycles in an ester-based electrolyte.The effect of the hierarchically porous loose sponge-like structure on the formation dynamics of solid electrolyte interphase(SEI),and related properties,was studied via cyclic voltammetry(CV),galvanostatic intermittent titration technique(GITT),X-ray photoelectron spectroscope(XPS),Fourier transform infrared spectroscopy(FTIR)and electrochemical impedance spectroscopy(EIS)analysis.These results reveal that the hierarchically porous structure can construct continued connecting channels and accelerate the electrolyte transport,which is beneficial to the reaction kinetics of SEI.Moreover,the mesoporous structure is conducive to good contact between electrolyte and materials and shortens the Na+diffusion path,which in turn facilitates the charge transfer kinetics in the material.展开更多
Zero-dimensional(0D)carbon quantum dots(CQDs),as a nanocarbon material in the carbon family,have garnered increasing attention in recent years due to their outstanding features of low cost,nontoxicity,large surface ar...Zero-dimensional(0D)carbon quantum dots(CQDs),as a nanocarbon material in the carbon family,have garnered increasing attention in recent years due to their outstanding features of low cost,nontoxicity,large surface area,high electrical conductivity,and rich surface functional groups.By virtue of their rapid electron transfer and large surface area,CQDs also emerge as promising functional materials for the applications in energy-conversion sectors through electrocatalysis.Besides,the rich functional groups on the surface of CQDs offer abundant anchoring sites and active sites for the engineering of multicomponent and high-performance composite materials.More importantly,the heteroatom in the CQDs could effectively tailor the charge distribution to promote the electron transfer via internal interactions,which is crucial to the enhancement of electrocatalytic performance.Herein,an overview about recent progress in preparing CQDs-based composites and employing them as promising electrode materials to promote the catalytic activity and stability for electrocatalysis is provided.The introduced CQDs could enhance the conductivity,modify the morphology and crystal phase,optimize the electronic structure,and provide more active centers and defect sites of composites.After establishing a deep understanding of the relationship between CQDs and electrocatalytic performances,the issues and challenges for the development of CQDs-based composites are discussed.展开更多
Efficient N fertilizer management is critical for the economic production of rice and the long-term protection of environmental quality. A field experiment was designed to study the effects of N fertilizer management ...Efficient N fertilizer management is critical for the economic production of rice and the long-term protection of environmental quality. A field experiment was designed to study the effects of N fertilizer management practices on grain yield and N uptake office. The experiment was laid out in the randomized complete block design with four replications in Central China during 2008 and 2009. Five N treatments denoted as No, NIsoA, N15oB, N24OA, and N24oB, respectively, were studied. NO represented no N application and served as a control, N15OA and N15oB indicated the total N application of 150 kg N ha-I but with two different application schedules （A and B） across the early stage of rice growth. Schedule A was applied as follows： 40% basal, 30% at 10 d after transplanting （DAT） and 30% at 36 DAT （nearly at the panicle initiation stage）, while schedule B was as follows： 30% at basal, 20% at 10 DAT, and 50% at 36 DAT. Similarly, N240A and N240B indicated the total N application of 240 kg N ha-1 with schedules A and B as described above. To quantify N uptake from fertilizer and soil, a 15N experiment was also conducted within the main experimental field, with micro-plots. Grain yields were significantly increased as N rates increased from 0 to 240 kg N ha-1. At the same rate, splitting N application as schedule B significantly increased the grain yield, spikelets per panicle, percentage of ripened grain, and 1 000-grain weight, compared with the N application according to schedule A. Mean rice recovery of N fertilizer by ~SN tracing method ranged from 25.39% at N24oA to 34.89% at NIsoB, however, N fertilizer residual rate in the soil ranged from 12.40% at N240A to 16.61% at N^s0w About 31.5 and 28.5% of total uptake of ~SN derived from basal fertilizer was absorbed at panicle initiation and heading stages, respectively. However, 65.6-92.5% of total uptake of 15N derived from topdressing fertilizer was absorbed at the heading stage. Based on yield and nitrogen recovery efficiency, splitting N applicati展开更多
文摘Background Although the first leading cause of death in China was malignant neoplasms （mortality, 374.1 per 100 000 person-years）, the full impact of primary brain tumors （PBT） on the healthcare system is not completely described because there are a few well documented reports about the epidemiologic features of brain tumors. This study aimed to report a comprehensive assessment on the prevalence of PBT. Methods A multicenter cross-sectional study on brain tumor （MCSBT） in China was initiated in five regional centers： Daqing （northeast）, Puyang （north of China）, Shiyan （center of China）, Ma＇anshan （center of China） and Shanghai （southeast）. Prevalence rate was calculated by counting the number of people living with a PBT between October 1,2005 and September 30, 2006 and dividing by the total population of the five communities at January 1, 2006. Estimates of prevalence were expressed as percentages and grouped according to gender and to age in fifteen-year categories. Within these strata, the rates were estimated with 95% confidence intervals （C/） using the accurate calculation of CI for Poisson distribution. A chi-square test was used to compare the various frequencies with a 〈0.05. Age-standardized prevalence with the direct method was calculated with the ten-year age-specific prevalence and the age distribution of population prospects： the 2008 revision. Results We estimated that the overall prevalence of PBT was 24.56 per 100 000 （95% CI, 14.85 to 34.27）, and the overall prevalence of PBT in female population （30.57 per 100 000 and its 95% Cl ranged from 19.73 to 41.41） was higher than that in male population （18.84 per 100 000 and its 95% Cl ranged from 10.33 to 27.35）. However, the discrepancy between genders was not statistically significant because the 95% Cl overlapped. Of 272 cases of newly diagnosed PBT, the proportion of histological subtypes by age groups, gender was statistically different （X2=52.6510, P 〈0.0001）. More than half of all re
文摘There are three types of shale gas resources in China.The resources are present in large amounts and are widely distributed.Marine facies,transitional facies and continental facies resources each account for a third.Based on resource distributions,there are many wells penetrated into the Sinian,Cambrian, Ordovieian,Silurian,Devonian,Carboniferous and Permian strata of the Yangtze plate and its periphery, the North China Craton and the Tarim Basin.Many years of exploration have indicated that the marine Silurian Longmaxi shale gas is widely distributed in south China and has been industrialized in its production in the Siehuan basin.The shale gas from the Cambrian Niutitang Formation and the Sinian Doushantuo Formation are important discoveries in Yichang,Hub ei and Zhenba,Shanxi.There are also shale gas resources found within transitional facies and continental facies in different areas in China.The "two element enrichment theory"has been summarized during the exploration process of Silurian marine shale gas in the Sichuan Basin.In addition,horizontal drilling and fracturing technologies up to 3500 m in depth have been developed.Based on the understanding of shale gas accumulation in a complex tectonic zone outside the Sichnan basin,a preliminary summary of the formation of the "converse fault syneline control reservoir"and "paleo uplift control reservoir"model has been constructed.The dominant theory of "Trinity"shale gas enrichment and the high yield of the "deep water Lu Pengxiang sedimentary facies belt, structural preservation conditions and overpressure"is summarized.Guided by the above theories.Anyel well in Guizhou and Eyangyel well in Hubei were drilled."Four storey"oil and shale "gas is found in the Permian Qixia group,the Silurian Shiniulan Formation,the Longmaxi Formation and the Ordovician Baota Formation in Anyel well.Good shale gas has been gound in the Cambrian Niutitang formation inian Doushantuo formation in Eyangye lwell.This paper aims to summarize and review the main progress,theoretical tech
文摘Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.
基金financially supported by the National Natural Science Foundation of China(Nos.U1804129,21771164,21671205 and U1804126)Zhongyuan Youth Talent Support Program of Henan Province and Zhengzhou University Youth Innovation Program。
文摘Hard carbon is the most promising anode for sodium-ion battery applications due to the wide availability and low work voltage.However,it often delivers worse electrochemical performance in ester-based electrolytes.Herein,a hierarchically porous loose sponge-like hard carbon with a highly disordered phase,prepared from the biomass of platanus bark,exhibits superior rate performance with a capacity of 165 mAh·g-1 at a high current of1 A·g-1,and high retention of 71.5%after 2000 cycles in an ester-based electrolyte.The effect of the hierarchically porous loose sponge-like structure on the formation dynamics of solid electrolyte interphase(SEI),and related properties,was studied via cyclic voltammetry(CV),galvanostatic intermittent titration technique(GITT),X-ray photoelectron spectroscope(XPS),Fourier transform infrared spectroscopy(FTIR)and electrochemical impedance spectroscopy(EIS)analysis.These results reveal that the hierarchically porous structure can construct continued connecting channels and accelerate the electrolyte transport,which is beneficial to the reaction kinetics of SEI.Moreover,the mesoporous structure is conducive to good contact between electrolyte and materials and shortens the Na+diffusion path,which in turn facilitates the charge transfer kinetics in the material.
基金supported by The Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJB150019)Youth Science and Technology Talents Enrollment Project of the Jiangsu Association of Science and Technology。
文摘Zero-dimensional(0D)carbon quantum dots(CQDs),as a nanocarbon material in the carbon family,have garnered increasing attention in recent years due to their outstanding features of low cost,nontoxicity,large surface area,high electrical conductivity,and rich surface functional groups.By virtue of their rapid electron transfer and large surface area,CQDs also emerge as promising functional materials for the applications in energy-conversion sectors through electrocatalysis.Besides,the rich functional groups on the surface of CQDs offer abundant anchoring sites and active sites for the engineering of multicomponent and high-performance composite materials.More importantly,the heteroatom in the CQDs could effectively tailor the charge distribution to promote the electron transfer via internal interactions,which is crucial to the enhancement of electrocatalytic performance.Herein,an overview about recent progress in preparing CQDs-based composites and employing them as promising electrode materials to promote the catalytic activity and stability for electrocatalysis is provided.The introduced CQDs could enhance the conductivity,modify the morphology and crystal phase,optimize the electronic structure,and provide more active centers and defect sites of composites.After establishing a deep understanding of the relationship between CQDs and electrocatalytic performances,the issues and challenges for the development of CQDs-based composites are discussed.
基金supported by the Key Technologies R&D Program of China during the 12th Five-Year Plan period(2011BAD16B02)the Natural Science Foundation of Guangdong Province, China(S2011040004466)
文摘Efficient N fertilizer management is critical for the economic production of rice and the long-term protection of environmental quality. A field experiment was designed to study the effects of N fertilizer management practices on grain yield and N uptake office. The experiment was laid out in the randomized complete block design with four replications in Central China during 2008 and 2009. Five N treatments denoted as No, NIsoA, N15oB, N24OA, and N24oB, respectively, were studied. NO represented no N application and served as a control, N15OA and N15oB indicated the total N application of 150 kg N ha-I but with two different application schedules （A and B） across the early stage of rice growth. Schedule A was applied as follows： 40% basal, 30% at 10 d after transplanting （DAT） and 30% at 36 DAT （nearly at the panicle initiation stage）, while schedule B was as follows： 30% at basal, 20% at 10 DAT, and 50% at 36 DAT. Similarly, N240A and N240B indicated the total N application of 240 kg N ha-1 with schedules A and B as described above. To quantify N uptake from fertilizer and soil, a 15N experiment was also conducted within the main experimental field, with micro-plots. Grain yields were significantly increased as N rates increased from 0 to 240 kg N ha-1. At the same rate, splitting N application as schedule B significantly increased the grain yield, spikelets per panicle, percentage of ripened grain, and 1 000-grain weight, compared with the N application according to schedule A. Mean rice recovery of N fertilizer by ~SN tracing method ranged from 25.39% at N24oA to 34.89% at NIsoB, however, N fertilizer residual rate in the soil ranged from 12.40% at N240A to 16.61% at N^s0w About 31.5 and 28.5% of total uptake of ~SN derived from basal fertilizer was absorbed at panicle initiation and heading stages, respectively. However, 65.6-92.5% of total uptake of 15N derived from topdressing fertilizer was absorbed at the heading stage. Based on yield and nitrogen recovery efficiency, splitting N applicati
