Due to the limitations of the raw materials and processes involved,polyolefin separators used in commercial lithium-ion batteries(LIBs)have gradually failed to meet the increasing requirements of high-end batteries in...Due to the limitations of the raw materials and processes involved,polyolefin separators used in commercial lithium-ion batteries(LIBs)have gradually failed to meet the increasing requirements of high-end batteries in terms of energy density,power density,and safety.Hence,it is very important to develop next-generation separators for advanced lithium(Li)-based recharge-able batteries including LIBs and Li-S batteries.Nonwoven nanofiber membranes fabricated via electrospinning technology are highly attractive candidates for high-end separators due to their simple processes,low-cost equipment,controllable microporous structure,wide material applicability,and availability of multiple functions.In this review,the electrospinning technologies for separators are reviewed in terms of devices,process and environment,and polymer solution systems.Furthermore,strategies toward the improvement of electrospun separators in advanced LIBs and Li-S batteries are presented in terms of the compositions and the structure of nanofibers and separators.Finally,the challenges and prospects of electrospun separators in both academia and industry are proposed.We anticipate that these systematic discussions can provide information in terms of commercial applications of electrospun separators and offer new perspectives for the design of functional electrospun separators for advanced Li-based batteries.展开更多
In the model of the vehicle recognition algorithm implemented by the convolutional neural network,the model needs to compute and store a lot of parameters.Too many parameters occupy a lot of computational resources ma...In the model of the vehicle recognition algorithm implemented by the convolutional neural network,the model needs to compute and store a lot of parameters.Too many parameters occupy a lot of computational resources making it difficult to run on computers with poor performance.Therefore,obtaining more efficient feature information of target image or video with better accuracy on computers with limited arithmetic power becomes the main goal of this research.In this paper,a lightweight densely connected,and deeply separable convolutional network(DCDSNet)algorithmis proposed to achieve this goal.Visual Geometry Group(VGG)model is improved by utilizing the convolution instead of the fully connected module,the deeply separable convolution module,and the densely connected network module,with the first two modules reducing the parameters and the third module allowing the algorithm to have more features in a limited number of parameters.The algorithm achieves better results in the mine vehicle recognition dataset.Experiments show that the recognition accuracy is improved by 4.41% compared to VGG19 and the amount of parameters is reduced by 71% compared to VGG19.展开更多
In this work,an amorphous ZnO was coated on LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)using a sol-gel strategy method.The NCM coated with 1 wt.%Zn O and a thickness of about 3 nm exhibits an improved cycling performance,acc...In this work,an amorphous ZnO was coated on LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)using a sol-gel strategy method.The NCM coated with 1 wt.%Zn O and a thickness of about 3 nm exhibits an improved cycling performance,accompanied by a lower capacity fading(from 194.8 to 133.8 m Ah g^(-1),i.e.,68%)than that of the pristine one(i.e.,only 34%)after 300 cycles at 0.2 C.The cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)indicate that the Zn O coating can improve extraction/insertion of Li+and inhibit the increase in impedance of the NCM cathode material.This approach may benefit the performance improvement of the Ni-rich cathode materials in Lithium-ion batteries(LIBs).展开更多
The development of high-voltage direct current gas-insulated switchgear assemblies(DC GIS)of rated voltages up to±550 kV has been completed.DC GIS provide a compact technical solution with a high functional densi...The development of high-voltage direct current gas-insulated switchgear assemblies(DC GIS)of rated voltages up to±550 kV has been completed.DC GIS provide a compact technical solution with a high functional density,optimized for projects with limited space as in offshore HVDC converter platforms,onshore HVDC converter stations and transition stations between different transmission media.Up to now,no standards for testing of gas-insulated DC systems are available,although pre-standardization work is in progress within CIGRE.Some tests can be performed as required in AC GIS standards.Special aspects of DC voltage stress,like the electric field distribution of insulators influenced by the accumulation of electrical charge carriers and the operation-related inhomogeneous temperature distribution,must be considered by additional electric and thermoelectric tests.For DC GIS,the experience of long-term performance is limited today.Although ageing is expected to be of lower importance,tests are recommended.This contribution summarizes the physical and technical background to design and develop compact DC switchgear assemblies using gas-insulated technology.It explains the developed modules of the substation and gives an overview of the performed tests.Furthermore,it provides an insight in the on-going standardization activities and describes applications in converter and transition stations,showing its space-saving characteristics.展开更多
Lithium(Li)metal is a potential anode for high-energy-density batteries because of its low potential and ultrahigh capacity.Nevertheless,the Li dendrites formation,the ununiform Li deposition,and the growth of Li dend...Lithium(Li)metal is a potential anode for high-energy-density batteries because of its low potential and ultrahigh capacity.Nevertheless,the Li dendrites formation,the ununiform Li deposition,and the growth of Li dendrites hamper its application,especially under high deposition capacity/high rate.Here,a spatially controlled Li deposition mode with array-oriented morphology is achieved based on the novel mixed ion/electron-conducting Li_(x)Cu_(y)P_(z) arrays constructed on Cu foil,which can be facile fabricated via an in-situ transformation of metal phosphide.Theoretic calculations indicate the excellent lithiophilicity and low Li diffusion barrier of the arrays,especially for the Li_(2)CuP phase,which are conducive to ho-mogenizing the Li nucleation/deposition of Li.Moreover,such mixed conducting arrays promote fast Li+diffusion via the continuous Li+pathways as well as modulate the Li+flux/electric field.Furthermore,the arrays with enlarged specific surface area and open spaces reduce the local current density and alle-viate the volume fluctuation of Li.Consequently,a dendrite-free Li anode is obtained under a high rate(20 mA cm^(–2))or a high deposition capacity(10 mAh cm^(–2)).In addition,even if the negative/positive ratio reduces to only 1.1,the full cells still perform outstanding stability for over 200 cycles.This work empha-sizes the importance of the design of the framework in terms of the intrinsic properties and structure and reveals a pathway for developing Li metal batteries.展开更多
Industrial NH3 production mainly employs the well‐known Haber‐Bosch(H‐B)process,which is associated with significant energy consumption and carbon emissions.Photoelectrochemical nitro‐gen reduction reaction(PEC‐N...Industrial NH3 production mainly employs the well‐known Haber‐Bosch(H‐B)process,which is associated with significant energy consumption and carbon emissions.Photoelectrochemical nitro‐gen reduction reaction(PEC‐NRR)under ambient conditions is considered a promising alternative to the H‐B process and has been attracting increasing attention owing to its associated energy effi‐ciency and environmentally friendly characteristics.The performance of a PEC‐NRR system,such as the NH_(3) yield,selectivity,and stability,is essentially determined by its key component,the photo‐cathode.In this review,the latest progress in the development of photocathode materials employed in PEC‐NRR is evaluated.The fundamental mechanisms and essential features required for the PEC‐NRR are introduced,followed by a discussion of various types of photocathode materials,such as oxides,sulfides,selenides,black silicon,and black phosphorus.In particular,the PEC‐NRR reac‐tion mechanisms associated with these photocathode materials are reviewed in detail.Finally,the present challenges and future opportunities related to the further development of PEC‐NRR are also discussed.This review aims to improve the understanding of PEC‐NRR photocathode materials while also shedding light on the new concepts and significant innovations in this field.展开更多
This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in ...This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.展开更多
Diamond-like carbon (DLC) films on ultra-high molecular weight polyethylene substrates were prepared at CHn+ ion bombarding energies of 200-1000eV at room temperature using ion beam assisted deposition technique. The ...Diamond-like carbon (DLC) films on ultra-high molecular weight polyethylene substrates were prepared at CHn+ ion bombarding energies of 200-1000eV at room temperature using ion beam assisted deposition technique. The wear tests exhibited a high wear resistance for all DLC films. X-ray photoelectron spectfoscopy and Raman spectroscopy analysis indicated that DLC film was amorphous with a characteristic high fracdion of sp3 bonds in the structure of mixed sp:2+ sp3 bonding at an optimal bombardingenergy of 600eV.展开更多
Multilayered ZrAlN/ZrB2 coatings containing alternating bilayer periods were synthesized by dc magnetron sputtering technique. The intensities of ZrN （111） or ZrN （200） textures in the structure of the nanolayers ...Multilayered ZrAlN/ZrB2 coatings containing alternating bilayer periods were synthesized by dc magnetron sputtering technique. The intensities of ZrN （111） or ZrN （200） textures in the structure of the nanolayers depended on the bilayer period as well as N2 gas partial pressure during deposition. Nanoindentation testing showed that hardness and internal stress of the nanolayers varied with the bilayer period and crystallographic orientation in the coatings. The hardness of the nanolayers with bilayer periods of 3-6 nm was enhanced （-27%） over the rule-of-mixture value. A low percent of N2 in processing gas was proved to be benefitial to the synthesis of high hard nanoscale multilayered coatings.展开更多
Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is re...Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is removed,which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level.Here,we conducted a two-year N addition experiment under two different topography positions(i.e.a slope and a valley)in a N-saturated subtropical forest.Soil enzyme activity was measured,and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation.Results:In the valley,two-year N addition changed the activity of all studied enzymes to various degrees.As a result,microbial C limitation was aggravated in the valley,and consequently microbial decomposition of soil labile organic C increased,but microbial P limitation was alleviated due to the stoichiometry balance.On the slope,however,N addition did not significantly change the activity of the studied enzymes,and did not alter the status of microbial resource limitation.Conclusions:These results indicate that C is a more limited element for microbial growth than P after removing N limitation,but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests.These findings provide useful supplements to the N saturation theory.展开更多
The relative limitation of microbes by soil organic carbon(SOC),nitrogen(N)and phosphorus(P)is linked with soil microbial activities,so how change of plant species diversity(PSD)affects microbial resource limitation w...The relative limitation of microbes by soil organic carbon(SOC),nitrogen(N)and phosphorus(P)is linked with soil microbial activities,so how change of plant species diversity(PSD)affects microbial resource limitation would partly determine its impacts on SOC dynamics and nutrient cycling.However,the responses of microbial resource limitation to increasing PSD have poorly explored.Here,45 plots covering a natural PSD gradient were used to investigate the effects of PSD on microbial resource limitation in a subtropical forest.Extracellular enzymatic stoichiometry along with a laboratory N and P addition experiment were used to determine microbial resource limitation.Contents of microbial biomass C,N and P significantly increased,but C:P and N:P ratios in microbial biomass were unchanged as PSD increased.Soil microbes were generally co-limited by C and P,but not by N across the 45 plots.Increasing PSD did not alter microbial N limitation,alleviated microbial C limitation and aggravated microbial P limitation.The alleviated microbial C limitation or aggravated microbial P limitation was attributed to increased soil C availability but decreased P availability,which resulted in stimulated soil C:P and N:P ratios and in turn greater C:P and N:P imbalance between soil and microbial biomass under higher PSD.Our results highlight the divergent effects of increasing PSD on microbial resource limitation.Considering that microbial C and P limitations are widespread,the patterns observed in the current study should be applicable broadly.展开更多
Soil microbial functions are closely related to ecosystem productivity,carbon sequestration and their responses to global change.Tree phylogenetic diversity(TPD)has been found to impact microbial community composition...Soil microbial functions are closely related to ecosystem productivity,carbon sequestration and their responses to global change.Tree phylogenetic diversity(TPD)has been found to impact microbial community composition,diversity and functions,but how it modulates the linkage between microbial community facets and functions remains unclear.Here,45 plots covering a natural gradient of TPD were selected in a subtropical forest of southwest China to explore how increasing TPD impacts soil microbial community facets and microbial functional potential.The microbial functional potential was evaluated based on the abundances of carbon,nitrogen and phosphorus cycling-related functional genes.Soil fungal alpha diversity increased significantly,but bacterial alpha diversity did not change as TPD increased.Both soil microbial network complexity and stability improved significantly with increasing TPD.Ultimately,increasing TPD promoted soil microbial functional potential by stimulating soil carbon and nitrogen availability,microbial keystone diversity and network stability collectively.These findings emphasize the critical roles of keystone taxa and network stability as microbial factors in stimulating soil microbial function in response to increasing TPD.Therefore,it is strongly recommended to increase TPD so as to stimulate soil microbial functions and other ecosystem functions when implementing afforestation or ecological restoration projects.展开更多
To identify useful genes from wild rice which have been lost or weakened in cultivated rice has become more and more important for modern breeding strategy. In this study, a BC4 population derived from 94W1, an access...To identify useful genes from wild rice which have been lost or weakened in cultivated rice has become more and more important for modern breeding strategy. In this study, a BC4 population derived from 94W1, an accession of common wild rice (Oryza rufipogon Griff.) from Dongxiang in Jiangxi Province of China, as the donor, and a high-yielding Indica cultivar (O. sativa L.), 'Guichao 2', as the recipient, was used to identify quantitative trait loci (QTL) associated with yield and its components. Based on the analysis for the genotype of BC4F1 population with 87 SSR markers distributed throughout the genome and investigation of the plant height, yield and yield components of BC4F2, a total of 52 QTLs, were detected. Of 7 QTLs associated with grain yield per plant, 2 QTLs on chromosome 2 and chromosome 11 for grain yield, explaining 16% and 11% of the phenotypic variance respectively, were identified. The alleles from Dongxiang common wild rice in those two loci could increase the yield of 'Guichao 2' by展开更多
Eucommia ulmoides, also called hardy rubber tree, is an economically important tree; however, the lack of its genome sequence restricts the fundamental biological research and applied studies of this plant species. He...Eucommia ulmoides, also called hardy rubber tree, is an economically important tree; however, the lack of its genome sequence restricts the fundamental biological research and applied studies of this plant species. Here, we present a high-quality assembly of its ~l.2-Gb genome （scaffold N50 = 1.88 Mb） with at least 26 723 predicted genes for E. ulmoides, the first sequenced genome of the order Garryales, which was obtained using an integrated strategy combining Illumina sequencing, PacBio sequencing, and BioNano mapping. As a sister taxon to lamiids and campanulids, E. ulmoides underwent an ancient genome triplication shared by core eudicots but no further whole-genome duplication in the last ~125 million years. E. ulmoides exhibits high expression levels and/or gene number expansion for multiple genes involved in stress responses and the biosynthesis of secondary metabolites, which may account for its considerable environmental adaptability. In contrast to the rubber tree （Hevea brasiliensis）, which produces cis-polyisoprene, E. ulmoides has evolved to synthe- size long-chain trans-polyisoprene via farnesyl diphosphate synthases （FPSs）. Moreover, FPS and rub- ber elongation factor/small rubber particle protein gene families were expanded independently from the H. brasiliensis lineage. These results provide new insights into the biology of E. ulmoides and the origin of polyisoprene biosynthesis.展开更多
基金The authors gratefully acknowledge financial support from Dagong Equipment Manufacturing(Tianjin)Co.,Ltd.(53H23019)the Tianjin Research Innovation Project for Postgraduate Students(2022BKYZ037)the National Natural Science Foundation of China(22179093).
文摘Due to the limitations of the raw materials and processes involved,polyolefin separators used in commercial lithium-ion batteries(LIBs)have gradually failed to meet the increasing requirements of high-end batteries in terms of energy density,power density,and safety.Hence,it is very important to develop next-generation separators for advanced lithium(Li)-based recharge-able batteries including LIBs and Li-S batteries.Nonwoven nanofiber membranes fabricated via electrospinning technology are highly attractive candidates for high-end separators due to their simple processes,low-cost equipment,controllable microporous structure,wide material applicability,and availability of multiple functions.In this review,the electrospinning technologies for separators are reviewed in terms of devices,process and environment,and polymer solution systems.Furthermore,strategies toward the improvement of electrospun separators in advanced LIBs and Li-S batteries are presented in terms of the compositions and the structure of nanofibers and separators.Finally,the challenges and prospects of electrospun separators in both academia and industry are proposed.We anticipate that these systematic discussions can provide information in terms of commercial applications of electrospun separators and offer new perspectives for the design of functional electrospun separators for advanced Li-based batteries.
基金supported by the open project of National Local Joint Engineering Research Center for Agro-Ecological Big Data Analysis and Application Technology,“Adaptive Agricultural Machinery Motion Detection and Recognition in Natural Scenes”,AE202210By the school-level key discipline of Suzhou University in China with No.2019xjzdxk12022 Anhui Province College Research Program Project of the Suzhou Vocational College of Civil Aviation,No.2022AH053155.
文摘In the model of the vehicle recognition algorithm implemented by the convolutional neural network,the model needs to compute and store a lot of parameters.Too many parameters occupy a lot of computational resources making it difficult to run on computers with poor performance.Therefore,obtaining more efficient feature information of target image or video with better accuracy on computers with limited arithmetic power becomes the main goal of this research.In this paper,a lightweight densely connected,and deeply separable convolutional network(DCDSNet)algorithmis proposed to achieve this goal.Visual Geometry Group(VGG)model is improved by utilizing the convolution instead of the fully connected module,the deeply separable convolution module,and the densely connected network module,with the first two modules reducing the parameters and the third module allowing the algorithm to have more features in a limited number of parameters.The algorithm achieves better results in the mine vehicle recognition dataset.Experiments show that the recognition accuracy is improved by 4.41% compared to VGG19 and the amount of parameters is reduced by 71% compared to VGG19.
基金supported by the Natural Science Basic Research Plan in Shaanxi Province of China(2019JLP-04)the National Natural Science Foundation of China(51672189)+1 种基金Xi’an Science and Technology Project of China(201805037YD15CG21(20))Tianjin Science and Technology Project(18PTZWHZ00020)
文摘In this work,an amorphous ZnO was coated on LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)(NCM)using a sol-gel strategy method.The NCM coated with 1 wt.%Zn O and a thickness of about 3 nm exhibits an improved cycling performance,accompanied by a lower capacity fading(from 194.8 to 133.8 m Ah g^(-1),i.e.,68%)than that of the pristine one(i.e.,only 34%)after 300 cycles at 0.2 C.The cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)indicate that the Zn O coating can improve extraction/insertion of Li+and inhibit the increase in impedance of the NCM cathode material.This approach may benefit the performance improvement of the Ni-rich cathode materials in Lithium-ion batteries(LIBs).
基金supported by the Federal Ministry for Economic Affairs and Energy, Germany (FKZ:03ET7511C)the Bavarian Ministry of Economic Affairs, Regional Development and Energy (FKZ:IET-1208-0018)
文摘The development of high-voltage direct current gas-insulated switchgear assemblies(DC GIS)of rated voltages up to±550 kV has been completed.DC GIS provide a compact technical solution with a high functional density,optimized for projects with limited space as in offshore HVDC converter platforms,onshore HVDC converter stations and transition stations between different transmission media.Up to now,no standards for testing of gas-insulated DC systems are available,although pre-standardization work is in progress within CIGRE.Some tests can be performed as required in AC GIS standards.Special aspects of DC voltage stress,like the electric field distribution of insulators influenced by the accumulation of electrical charge carriers and the operation-related inhomogeneous temperature distribution,must be considered by additional electric and thermoelectric tests.For DC GIS,the experience of long-term performance is limited today.Although ageing is expected to be of lower importance,tests are recommended.This contribution summarizes the physical and technical background to design and develop compact DC switchgear assemblies using gas-insulated technology.It explains the developed modules of the substation and gives an overview of the performed tests.Furthermore,it provides an insight in the on-going standardization activities and describes applications in converter and transition stations,showing its space-saving characteristics.
基金This work was supported by the National Science Foundation of Tianjin(No.20JCQNJC00500)。
文摘Lithium(Li)metal is a potential anode for high-energy-density batteries because of its low potential and ultrahigh capacity.Nevertheless,the Li dendrites formation,the ununiform Li deposition,and the growth of Li dendrites hamper its application,especially under high deposition capacity/high rate.Here,a spatially controlled Li deposition mode with array-oriented morphology is achieved based on the novel mixed ion/electron-conducting Li_(x)Cu_(y)P_(z) arrays constructed on Cu foil,which can be facile fabricated via an in-situ transformation of metal phosphide.Theoretic calculations indicate the excellent lithiophilicity and low Li diffusion barrier of the arrays,especially for the Li_(2)CuP phase,which are conducive to ho-mogenizing the Li nucleation/deposition of Li.Moreover,such mixed conducting arrays promote fast Li+diffusion via the continuous Li+pathways as well as modulate the Li+flux/electric field.Furthermore,the arrays with enlarged specific surface area and open spaces reduce the local current density and alle-viate the volume fluctuation of Li.Consequently,a dendrite-free Li anode is obtained under a high rate(20 mA cm^(–2))or a high deposition capacity(10 mAh cm^(–2)).In addition,even if the negative/positive ratio reduces to only 1.1,the full cells still perform outstanding stability for over 200 cycles.This work empha-sizes the importance of the design of the framework in terms of the intrinsic properties and structure and reveals a pathway for developing Li metal batteries.
文摘Industrial NH3 production mainly employs the well‐known Haber‐Bosch(H‐B)process,which is associated with significant energy consumption and carbon emissions.Photoelectrochemical nitro‐gen reduction reaction(PEC‐NRR)under ambient conditions is considered a promising alternative to the H‐B process and has been attracting increasing attention owing to its associated energy effi‐ciency and environmentally friendly characteristics.The performance of a PEC‐NRR system,such as the NH_(3) yield,selectivity,and stability,is essentially determined by its key component,the photo‐cathode.In this review,the latest progress in the development of photocathode materials employed in PEC‐NRR is evaluated.The fundamental mechanisms and essential features required for the PEC‐NRR are introduced,followed by a discussion of various types of photocathode materials,such as oxides,sulfides,selenides,black silicon,and black phosphorus.In particular,the PEC‐NRR reac‐tion mechanisms associated with these photocathode materials are reviewed in detail.Finally,the present challenges and future opportunities related to the further development of PEC‐NRR are also discussed.This review aims to improve the understanding of PEC‐NRR photocathode materials while also shedding light on the new concepts and significant innovations in this field.
基金supported by the National Key Research and Development Project(Grant No.2019YFA0606803,2016YFA0601704)the National Natural Science Foundation of China(Grant No.41925022)+1 种基金the Innovation and Development Project of China Meteorological Administration(CXFZ2022J036)the Science and Technology Development Fund of Hubei Meteorological Bureau(Grant No.2017Y06,2017Y07,2016Y06,2019Y10).
文摘This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.
文摘Diamond-like carbon (DLC) films on ultra-high molecular weight polyethylene substrates were prepared at CHn+ ion bombarding energies of 200-1000eV at room temperature using ion beam assisted deposition technique. The wear tests exhibited a high wear resistance for all DLC films. X-ray photoelectron spectfoscopy and Raman spectroscopy analysis indicated that DLC film was amorphous with a characteristic high fracdion of sp3 bonds in the structure of mixed sp:2+ sp3 bonding at an optimal bombardingenergy of 600eV.
基金This work is supported by the Applied Basic Key Project of Tianjin under grant No. 043801011 the National Natural Science Foundation of China （No. 50472026） This work is also supported by Joint Project of Tianjin Municipal Universities, Nankai University and Tianjin University, State Education Ministry under grant No. GJDF01.
文摘Multilayered ZrAlN/ZrB2 coatings containing alternating bilayer periods were synthesized by dc magnetron sputtering technique. The intensities of ZrN （111） or ZrN （200） textures in the structure of the nanolayers depended on the bilayer period as well as N2 gas partial pressure during deposition. Nanoindentation testing showed that hardness and internal stress of the nanolayers varied with the bilayer period and crystallographic orientation in the coatings. The hardness of the nanolayers with bilayer periods of 3-6 nm was enhanced （-27%） over the rule-of-mixture value. A low percent of N2 in processing gas was proved to be benefitial to the synthesis of high hard nanoscale multilayered coatings.
基金funded by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA13010302)the National Natural Science Foundation of China(Nos.31872691,41877094,and 31760153)+1 种基金Guangxi Bagui Scholarship Program to Dejun LiNational High-Level Talents Special Support Program to Dejun Li.
文摘Background:Nitrogen(N)saturation theory proposes that an ecosystem might switch from N limitation to carbon(C),phosphorus(P),or other nutrient limitations if it receives continuous N input.Yet,after N limitation is removed,which nutrient is the most limited and whether topography modulates such change is rarely tested at a microbial level.Here,we conducted a two-year N addition experiment under two different topography positions(i.e.a slope and a valley)in a N-saturated subtropical forest.Soil enzyme activity was measured,and ecoenzymatic stoichiometry indexes were calculated as indicators of microbial resource limitation.Results:In the valley,two-year N addition changed the activity of all studied enzymes to various degrees.As a result,microbial C limitation was aggravated in the valley,and consequently microbial decomposition of soil labile organic C increased,but microbial P limitation was alleviated due to the stoichiometry balance.On the slope,however,N addition did not significantly change the activity of the studied enzymes,and did not alter the status of microbial resource limitation.Conclusions:These results indicate that C is a more limited element for microbial growth than P after removing N limitation,but we also highlight that topography can regulate the effect of N deposition on soil microbial resource limitation in subtropical forests.These findings provide useful supplements to the N saturation theory.
基金National Natural Science Foundation of China(U21A2007).
文摘The relative limitation of microbes by soil organic carbon(SOC),nitrogen(N)and phosphorus(P)is linked with soil microbial activities,so how change of plant species diversity(PSD)affects microbial resource limitation would partly determine its impacts on SOC dynamics and nutrient cycling.However,the responses of microbial resource limitation to increasing PSD have poorly explored.Here,45 plots covering a natural PSD gradient were used to investigate the effects of PSD on microbial resource limitation in a subtropical forest.Extracellular enzymatic stoichiometry along with a laboratory N and P addition experiment were used to determine microbial resource limitation.Contents of microbial biomass C,N and P significantly increased,but C:P and N:P ratios in microbial biomass were unchanged as PSD increased.Soil microbes were generally co-limited by C and P,but not by N across the 45 plots.Increasing PSD did not alter microbial N limitation,alleviated microbial C limitation and aggravated microbial P limitation.The alleviated microbial C limitation or aggravated microbial P limitation was attributed to increased soil C availability but decreased P availability,which resulted in stimulated soil C:P and N:P ratios and in turn greater C:P and N:P imbalance between soil and microbial biomass under higher PSD.Our results highlight the divergent effects of increasing PSD on microbial resource limitation.Considering that microbial C and P limitations are widespread,the patterns observed in the current study should be applicable broadly.
基金supported by National Natural Science Foundation of China(U22A20560,U21A2007)International Partnership Program of Chinese Academy of Sciences(177GJHZ2022020BS).
文摘Soil microbial functions are closely related to ecosystem productivity,carbon sequestration and their responses to global change.Tree phylogenetic diversity(TPD)has been found to impact microbial community composition,diversity and functions,but how it modulates the linkage between microbial community facets and functions remains unclear.Here,45 plots covering a natural gradient of TPD were selected in a subtropical forest of southwest China to explore how increasing TPD impacts soil microbial community facets and microbial functional potential.The microbial functional potential was evaluated based on the abundances of carbon,nitrogen and phosphorus cycling-related functional genes.Soil fungal alpha diversity increased significantly,but bacterial alpha diversity did not change as TPD increased.Both soil microbial network complexity and stability improved significantly with increasing TPD.Ultimately,increasing TPD promoted soil microbial functional potential by stimulating soil carbon and nitrogen availability,microbial keystone diversity and network stability collectively.These findings emphasize the critical roles of keystone taxa and network stability as microbial factors in stimulating soil microbial function in response to increasing TPD.Therefore,it is strongly recommended to increase TPD so as to stimulate soil microbial functions and other ecosystem functions when implementing afforestation or ecological restoration projects.
基金This work was supported by the "973" Project (Grant No. 2001CB108800)China National High-Tech Research and Development Program ("863" Program)the National Tackle Key Problem Project of the Ministry of Science and Technology of China.
文摘To identify useful genes from wild rice which have been lost or weakened in cultivated rice has become more and more important for modern breeding strategy. In this study, a BC4 population derived from 94W1, an accession of common wild rice (Oryza rufipogon Griff.) from Dongxiang in Jiangxi Province of China, as the donor, and a high-yielding Indica cultivar (O. sativa L.), 'Guichao 2', as the recipient, was used to identify quantitative trait loci (QTL) associated with yield and its components. Based on the analysis for the genotype of BC4F1 population with 87 SSR markers distributed throughout the genome and investigation of the plant height, yield and yield components of BC4F2, a total of 52 QTLs, were detected. Of 7 QTLs associated with grain yield per plant, 2 QTLs on chromosome 2 and chromosome 11 for grain yield, explaining 16% and 11% of the phenotypic variance respectively, were identified. The alleles from Dongxiang common wild rice in those two loci could increase the yield of 'Guichao 2' by
文摘Eucommia ulmoides, also called hardy rubber tree, is an economically important tree; however, the lack of its genome sequence restricts the fundamental biological research and applied studies of this plant species. Here, we present a high-quality assembly of its ~l.2-Gb genome （scaffold N50 = 1.88 Mb） with at least 26 723 predicted genes for E. ulmoides, the first sequenced genome of the order Garryales, which was obtained using an integrated strategy combining Illumina sequencing, PacBio sequencing, and BioNano mapping. As a sister taxon to lamiids and campanulids, E. ulmoides underwent an ancient genome triplication shared by core eudicots but no further whole-genome duplication in the last ~125 million years. E. ulmoides exhibits high expression levels and/or gene number expansion for multiple genes involved in stress responses and the biosynthesis of secondary metabolites, which may account for its considerable environmental adaptability. In contrast to the rubber tree （Hevea brasiliensis）, which produces cis-polyisoprene, E. ulmoides has evolved to synthe- size long-chain trans-polyisoprene via farnesyl diphosphate synthases （FPSs）. Moreover, FPS and rub- ber elongation factor/small rubber particle protein gene families were expanded independently from the H. brasiliensis lineage. These results provide new insights into the biology of E. ulmoides and the origin of polyisoprene biosynthesis.
