Power-line interference is one of the most common noises in magnetotelluric(MT)data.It usually causes distortion at the fundamental frequency and its odd harmonics,and may also affect other frequency bands.Although tr...Power-line interference is one of the most common noises in magnetotelluric(MT)data.It usually causes distortion at the fundamental frequency and its odd harmonics,and may also affect other frequency bands.Although trap circuits are designed to suppress such noise in most of the modern acquisition devices,strong interferences are still found in MT data,and the power-line interference will fluctuate with the changing of load current.The fixed trap circuits often fail to deal with it.This paper proposes an alternative scheme for power-line interference removal based on frequency-domain sparse decomposition.Firstly,the fast Fourier transform of the acquired MT signal is performed.Subsequently,a redundant dictionary is designed to match with the power-line interference which is insensitive to the useful signal.Power-line interference is separated by using the dictionary and a signal reconstruction algorithm of compressive sensing called improved orthogonal matching pursuit(IOMP).Finally,the frequency domain data are switched back to the time domain by the inverse fast Fourier transform.Simulation experiments and real data examples from Lu-Zong ore district illustrate that this scheme can effectively suppress the power-line interference and significantly improve data quality.Compared with time domain sparse decomposition,this scheme takes less time consumption and acquires better results.展开更多
The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (...The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems.展开更多
In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads th...In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.展开更多
The use of lithium-sulfur(Li-S)batteries is limited by sulfur redox reactions involving multi-phase transformations,especially at low-temperatures.To address this issue,we report a material(FCNS@NCFs)consisting of nit...The use of lithium-sulfur(Li-S)batteries is limited by sulfur redox reactions involving multi-phase transformations,especially at low-temperatures.To address this issue,we report a material(FCNS@NCFs)consisting of nitrogen-doped carbon fibers loaded with a ternary metal sulf-ide((Fe,Co,Ni)_(9)S_(8))for use as the sulfur host in Li-S batteries.This materi-al was prepared using transfer blot filter paper as the carbon precursor,thiourea as the source of nitrogen and sulfur,and FeCl_(3)·6H_(2)O,CoCl_(2)·6H_(2)O and NiCl_(2)·6H_(2)O as the metal ion sources.It was synthesized by an impreg-nation method followed by calcination.The nitrogen doping significantly in-creased the conductivity of the host,and the metal sulfides have excellent catalytic activities.Theoretical calculations,and adsorption and deposition experiments show that active sites on the surface of FCNS@NCFs selectively adsorb polysulfides,facilitate rapid adsorption and conversion,prevent cathode passivation and inhib-it the polysulfide shuttling.The FCNS@NCFs used as the sulfur host has excellent electrochemical properties.Its initial dis-charge capacity is 1639.0 mAh g^(−1) at 0.2 C and room temperature,and it remains a capacity of 1255.1 mAh g^(−1) after 100 cycles.At−20~C,it has an initial discharge capacity of 1578.5 mAh g^(−1) at 0.2 C,with a capacity of 867.5 mAh g^(−1) after 100 cycles.Its excellent performance at both ambient and low temperatures suggests a new way to produce high-performance low-temper-ature Li-S batteries.展开更多
This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low ...This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low resolution thermal infrared imaging,various optimizations have been carried out to improve the speed and accuracy of thermal infrared 3D reconstruction.Firstly,inspired by Boltzmann's law of thermal radiation,distance is incorporated into the NeRF model for the first time,resulting in a nonlinear propagation of a single ray and a more accurate description of the physical property that infrared radiation intensity decreases with increasing distance.Secondly,in terms of improving inference speed,based on the phenomenon of high and low frequency distribution of foreground and background in infrared images,a multi ray non-uniform light synthesis strategy is proposed to make the model pay more attention to foreground objects in the scene,reduce the distribution of light in the background,and significantly reduce training time without reducing accuracy.In addition,compared to visible light scenes,infrared images only have a single channel,so fewer network parameters are required.Experiments using the same training data and data filtering method showed that,compared to the original NeRF,the improved network achieved an average improvement of 13.8%and 4.62%in PSNR and SSIM,respectively,while an average decreases of 46%in LPIPS.And thanks to the optimization of network layers and data filtering methods,training only takes about 25%of the original method's time to achieve convergence.Finally,for scenes with weak backgrounds,this article improves the inference speed of the model by 4-6 times compared to the original NeRF by limiting the query interval of the model.展开更多
One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific object...One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.展开更多
Background Soil available phosphorus(AP)deficiency significantly limits cotton production,particularly in arid and saline-alkaline regions.Screening cotton cultivars for low phosphorus(P)tolerance is crucial for the s...Background Soil available phosphorus(AP)deficiency significantly limits cotton production,particularly in arid and saline-alkaline regions.Screening cotton cultivars for low phosphorus(P)tolerance is crucial for the sustainable development of cotton production.However,the effect of different growth media on the screening outcomes remains unclear.To address this,we evaluated the low P tolerance of 25 cotton cultivars through hydroponic culture at two P levels(0.01 and 0.5 mmol·L^(-1) KH_(2)PO_(4))in 2018 and field culture with two P rates(0 and 90 kg·hm^(-2),in P2O5)in 2019.Results In the hydroponic experiments,principal component analysis(PCA)showed that shoot dry weight(SDW)and P utilization efficiency in shoots(PUES)of cotton seedlings explained over 45%of the genetic variation in P nutri-tion.Cotton cultivars were subjected to comprehensive cluster analysis,utilizing agronomic traits(SDW and PUES)during the seedling stage(hydroponic)and yield and fiber quality traits during the mature stage(in field).These cultivars were grouped into four clusters:resistant,moderately resistant,moderately sensitive,and sensitive.In low P conditions(0.01 mmol·L^(-1) KH_(2)PO_(4) and 4.5 mg·kg^(-1) AP),the low-P-resistant cluster showed significantly smaller reduc-tions in SDW(54%),seed cotton yield(3%),lint yield(-2%),fiber length(-1)%),and fiber strength(-3%)compared with the low-P-sensitive cluster(75%,13%,17%,7%,and 9%,respectively).The increase in PUES(299%)in the resist-ant cluster was also significantly higher than in the sensitive cluster(131%).Four of the eight low-P-tolerant cotton cultivars identified in the field and six in the hydroponic screening overlapped in both screenings.Two cultivars overlapped in both screening in the low-P-sensitive cluster.Conclusion Based on the screenings from both field and hydroponic cultures,ZM-9131,CCRI-79,JM-958,and J-228 were identified as low-P-tolerant cotton cultivars,while JM-169,XM-33B,SCRC-28,and LNM-18 were identified as low P-sensitive cotton cultivars.The relationship between field and hydroponic screening results for low-P-tolerant cotton cultivars was strong,although field validation is still required.The low P tolerance of these cultivars was closely associ-ated with SDW and PUES.展开更多
ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(...ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(2)-Nb_(2)O_(5)(CTN)ternary composite oxide additives with different composition ratios on sintering behavior and properties of ZnAl_(2)O_(4) microwave dielectric ceramics was investigated.When the molar fraction ranges of Cu,Ti and Nb elements in 5%CTN additives are 0.625-0.875,0-0.250 and 0.125-0.625,respectively,sintering temperature of ZnAl_(2)O_(4) ceramics can be reduced from above 1400℃to below 1000℃.The sintering additives CN(Cu:Nb=1:1,molar ratio)and CTN(Cu:Ti:Nb=4:1:3,molar ratio)can reduce sintering temperature of ZnAl_(2)O_(4) ceramics to 975 and 1000℃,respectively,while maintaining good dielectric properties(dielectric constantε_(r)=11.36,quality factor Q׃=8245 GHz andε_(r)=9.52,Q׃=22249 GHz)and flexural strengths(200 and 161 MPa),which are expected to be applied in preparation of low temperature co-fired ceramic(LTCC)materials with copper electrodes.Low-temperature sintering of the ZnAl_(2)O_(4)+CTN system is characterized as activated sintering.Nanometer-level amorphous interfacial films containing Cu,Ti,and Nb elements are observed at the grain boundaries,which may provide fast diffusion pathways for mass transportation during the sintering process.Valence changes of Ti and Cu ions,along with changes of oxygen vacancies,are confirmed,which provides a potential mechanism for reduced sintering temperature of ZnAl_(2)O_(4) ceramics.In addition,a series of reactions occurring at the grain boundaries can activate these boundaries and further promote the sintering densification process.These results suggest a promising way to design a novel LTCC material with excellent properties based on the low temperature sintering of ceramics with the sintering aid of CuO-TiO_(2)-Nb_(2)O_(5) composite oxide.展开更多
The new technology of direct decomposition of H_(2)S into high value-added H_(2) and S,as an alternative to the Claus process in industry,is an ideal route that can not only deal with toxic and abundant H_(2)S waste g...The new technology of direct decomposition of H_(2)S into high value-added H_(2) and S,as an alternative to the Claus process in industry,is an ideal route that can not only deal with toxic and abundant H_(2)S waste gas but also recover clean energy H_(2),which has significant socio-economic and ecological advantages.However,the highly effective decomposition of H_(2)S at low temperatures is still a great challenge,because of the stringent thermodynamic equilibrium constraints(only 20% even at high temperature of 1010℃).Conventional microwave catalysts exhibit unsatisfactory performance at low temperatures(below 600℃).Herein,Mo_(2)C@CeO_(2) catalysts with a core-shell structure were successfully developed for robust microwave catalytic decomposition of H_(2)S at low temperatures.Two carbon precursors,para-phenylenediamine(Mo_(2)C-p)and meta-phenylenediamine(Mo_(2)C-m),were employed to tailor Mo_(2)C configurations.Remarkably,the H_(2)S conversion of Mo_(2)C-p@CeO_(2) catalyst at a low temperature of 550℃ is as high as 92.1%,which is much higher than the H_(2)S equilibrium conversion under the conventional thermal conditions(2.6% at 550℃).To our knowledge,this represents the most active catalyst for microwave catalytic decomposition of H_(2)S at low temperature of 550℃.Notably,Mo_(2)C-p demonstrated superior intrinsic activity(84%)compared to Mo_(2)C-m(6.4%),with XPS analysis revealing that its enhanced performance stems from a higher concentration of Mo_(2+)active sites.This work presents a substitute approach for the efficient utilization of H_(2)S waste gas and opens up a novel avenue for the rational design of microwave catalysts for microwave catalytic reaction at low-temperature.展开更多
基金Project(2014AA06A602)supported by the National High-Tech Research and Development Program of ChinaProjects(41404111,41304098)supported by the National Natural Science Foundation of ChinaProject(2015JJ3088)supported by the Natural Science Foundation of Hunan Province,China
文摘Power-line interference is one of the most common noises in magnetotelluric(MT)data.It usually causes distortion at the fundamental frequency and its odd harmonics,and may also affect other frequency bands.Although trap circuits are designed to suppress such noise in most of the modern acquisition devices,strong interferences are still found in MT data,and the power-line interference will fluctuate with the changing of load current.The fixed trap circuits often fail to deal with it.This paper proposes an alternative scheme for power-line interference removal based on frequency-domain sparse decomposition.Firstly,the fast Fourier transform of the acquired MT signal is performed.Subsequently,a redundant dictionary is designed to match with the power-line interference which is insensitive to the useful signal.Power-line interference is separated by using the dictionary and a signal reconstruction algorithm of compressive sensing called improved orthogonal matching pursuit(IOMP).Finally,the frequency domain data are switched back to the time domain by the inverse fast Fourier transform.Simulation experiments and real data examples from Lu-Zong ore district illustrate that this scheme can effectively suppress the power-line interference and significantly improve data quality.Compared with time domain sparse decomposition,this scheme takes less time consumption and acquires better results.
基金Projects(51007021, 60402004) supported by the National Natural Science Foundation of China
文摘The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems.
基金Supported by the National Natural Science Foundation of China(61971401)。
文摘In this paper,a wideband true time delay line for X-band is designed to overcome the beam dispersion problem in a high-resolution spaceborne synthetic aperture radar phased array antenna system.The delay line loads the electromagnetic bandgap structure on the upper surface of the substrate integrated waveguide.This is equivalent to including an additional inductance-capacitance for energy storage,which realizes the slow-wave effect.A microstrip line-SIW tapered transition structure is introduced to achieve a low loss and a large bandwidth.In the frequency band between 8-12 GHz,the measured results show that the delay multiplier of the delay line reaches 4 times,i.e.,delay line’s delay time is 4 times larger than 50Ωmicrostrip line with same length.Furthermore,the delay fluctuation,i.e.,the difference between the maximum and minimum delay as a percentage of the standard delay is only 2.5%,the insertion loss is less than-2.5 dB,and the return loss is less than-15 dB.Compared with the existing delay lines,the proposed delay line has the advantages of high delay efficiency,low delay error,wide bandwidth and low loss,which has good practical value and application prospects.
基金partially supported by National Natural Science Foundation of China(52172250)Institute of Process Engineering(IPE)Project for Frontier Basic Research(QYJC-2023-06)。
文摘The use of lithium-sulfur(Li-S)batteries is limited by sulfur redox reactions involving multi-phase transformations,especially at low-temperatures.To address this issue,we report a material(FCNS@NCFs)consisting of nitrogen-doped carbon fibers loaded with a ternary metal sulf-ide((Fe,Co,Ni)_(9)S_(8))for use as the sulfur host in Li-S batteries.This materi-al was prepared using transfer blot filter paper as the carbon precursor,thiourea as the source of nitrogen and sulfur,and FeCl_(3)·6H_(2)O,CoCl_(2)·6H_(2)O and NiCl_(2)·6H_(2)O as the metal ion sources.It was synthesized by an impreg-nation method followed by calcination.The nitrogen doping significantly in-creased the conductivity of the host,and the metal sulfides have excellent catalytic activities.Theoretical calculations,and adsorption and deposition experiments show that active sites on the surface of FCNS@NCFs selectively adsorb polysulfides,facilitate rapid adsorption and conversion,prevent cathode passivation and inhib-it the polysulfide shuttling.The FCNS@NCFs used as the sulfur host has excellent electrochemical properties.Its initial dis-charge capacity is 1639.0 mAh g^(−1) at 0.2 C and room temperature,and it remains a capacity of 1255.1 mAh g^(−1) after 100 cycles.At−20~C,it has an initial discharge capacity of 1578.5 mAh g^(−1) at 0.2 C,with a capacity of 867.5 mAh g^(−1) after 100 cycles.Its excellent performance at both ambient and low temperatures suggests a new way to produce high-performance low-temper-ature Li-S batteries.
基金Support by the Fundamental Research Funds for the Central Universities(2024300443)the National Natural Science Foundation of China(NSFC)Young Scientists Fund(62405131)。
文摘This article proposes a three-dimensional light field reconstruction method based on neural radiation field(NeRF)called Infrared NeRF for low resolution thermal infrared scenes.Based on the characteristics of the low resolution thermal infrared imaging,various optimizations have been carried out to improve the speed and accuracy of thermal infrared 3D reconstruction.Firstly,inspired by Boltzmann's law of thermal radiation,distance is incorporated into the NeRF model for the first time,resulting in a nonlinear propagation of a single ray and a more accurate description of the physical property that infrared radiation intensity decreases with increasing distance.Secondly,in terms of improving inference speed,based on the phenomenon of high and low frequency distribution of foreground and background in infrared images,a multi ray non-uniform light synthesis strategy is proposed to make the model pay more attention to foreground objects in the scene,reduce the distribution of light in the background,and significantly reduce training time without reducing accuracy.In addition,compared to visible light scenes,infrared images only have a single channel,so fewer network parameters are required.Experiments using the same training data and data filtering method showed that,compared to the original NeRF,the improved network achieved an average improvement of 13.8%and 4.62%in PSNR and SSIM,respectively,while an average decreases of 46%in LPIPS.And thanks to the optimization of network layers and data filtering methods,training only takes about 25%of the original method's time to achieve convergence.Finally,for scenes with weak backgrounds,this article improves the inference speed of the model by 4-6 times compared to the original NeRF by limiting the query interval of the model.
基金Supported by the National Natural Science Foundation of China(42474239,41204128)China National Space Administration(Pre-research project on Civil Aerospace Technologies No.D010301)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA17010303)。
文摘One of the detection objectives of the Chinese Asteroid Exploration mission is to investigate the space environment near the Main-belt Comet(MBC,Active Asteroid)311P/PANSTARRS.This paper outlines the scientific objectives,measurement targets,and measurement requirements for the proposed Gas and Ion Analyzer(GIA).The GIA is designed for in-situ mass spectrometry of neutral gases and low-energy ions,such as hydrogen,carbon,and oxygen,in the vicinity of 311P.Ion sampling techniques are essential for the GIA's Time-of-Flight(TOF)mass analysis capabilities.In this paper,we present an enhanced ion sampling technique through the development of an ion attraction model and an ion source model.The ion attraction model demonstrates that adjusting attraction grid voltage can enhance the detection efficiency of low-energy ions and mitigate the repulsive force of ions during sampling,which is influenced by the satellite's surface positive charging.The ion source model simulates the processes of gas ionization and ion multiplication.Simulation results indicate that the GIA can achieve a lower pressure limit below 10-13Pa and possess a dynamic range exceeding 10~9.These performances ensure the generation of ions with stable and consistent current,which is crucial for high-resolution and broad dynamic range mass spectrometer analysis.Preliminary testing experiments have verified GIA's capability to detect gas compositions such as H2O and N2.In-situ measurements near 311P using GIA are expected to significantly contribute to our understanding of asteroid activity mechanisms,the evolution of the atmospheric and ionized environments of main-belt comets,the interactions with solar wind,and the origin of Earth's water.
基金the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2024D01A56)the National Key Research and Develop-ment Program of China(2017YFD0201906)+2 种基金the Central Research Institutes of Basic Research and the Public Service Special Foundation(1610162022044)the China Agriculture Research System(CARS-15-11)the Agricultural Sci-ence and Technology Innovation Program of Chinese Academy of Agricultural Sciences.
文摘Background Soil available phosphorus(AP)deficiency significantly limits cotton production,particularly in arid and saline-alkaline regions.Screening cotton cultivars for low phosphorus(P)tolerance is crucial for the sustainable development of cotton production.However,the effect of different growth media on the screening outcomes remains unclear.To address this,we evaluated the low P tolerance of 25 cotton cultivars through hydroponic culture at two P levels(0.01 and 0.5 mmol·L^(-1) KH_(2)PO_(4))in 2018 and field culture with two P rates(0 and 90 kg·hm^(-2),in P2O5)in 2019.Results In the hydroponic experiments,principal component analysis(PCA)showed that shoot dry weight(SDW)and P utilization efficiency in shoots(PUES)of cotton seedlings explained over 45%of the genetic variation in P nutri-tion.Cotton cultivars were subjected to comprehensive cluster analysis,utilizing agronomic traits(SDW and PUES)during the seedling stage(hydroponic)and yield and fiber quality traits during the mature stage(in field).These cultivars were grouped into four clusters:resistant,moderately resistant,moderately sensitive,and sensitive.In low P conditions(0.01 mmol·L^(-1) KH_(2)PO_(4) and 4.5 mg·kg^(-1) AP),the low-P-resistant cluster showed significantly smaller reduc-tions in SDW(54%),seed cotton yield(3%),lint yield(-2%),fiber length(-1)%),and fiber strength(-3%)compared with the low-P-sensitive cluster(75%,13%,17%,7%,and 9%,respectively).The increase in PUES(299%)in the resist-ant cluster was also significantly higher than in the sensitive cluster(131%).Four of the eight low-P-tolerant cotton cultivars identified in the field and six in the hydroponic screening overlapped in both screenings.Two cultivars overlapped in both screening in the low-P-sensitive cluster.Conclusion Based on the screenings from both field and hydroponic cultures,ZM-9131,CCRI-79,JM-958,and J-228 were identified as low-P-tolerant cotton cultivars,while JM-169,XM-33B,SCRC-28,and LNM-18 were identified as low P-sensitive cotton cultivars.The relationship between field and hydroponic screening results for low-P-tolerant cotton cultivars was strong,although field validation is still required.The low P tolerance of these cultivars was closely associ-ated with SDW and PUES.
基金National Natural Science Foundation of China (U24A2052)Shanghai Eastern Talent Plan。
文摘ZnAl_(2)O_(4) and ZnAl_(2)O_(4)-based ceramics have attracted much attention from researchers due to their good microwave dielectric,thermal and mechanical properties.In this work,the influence of 5%(in mass)CuO-TiO_(2)-Nb_(2)O_(5)(CTN)ternary composite oxide additives with different composition ratios on sintering behavior and properties of ZnAl_(2)O_(4) microwave dielectric ceramics was investigated.When the molar fraction ranges of Cu,Ti and Nb elements in 5%CTN additives are 0.625-0.875,0-0.250 and 0.125-0.625,respectively,sintering temperature of ZnAl_(2)O_(4) ceramics can be reduced from above 1400℃to below 1000℃.The sintering additives CN(Cu:Nb=1:1,molar ratio)and CTN(Cu:Ti:Nb=4:1:3,molar ratio)can reduce sintering temperature of ZnAl_(2)O_(4) ceramics to 975 and 1000℃,respectively,while maintaining good dielectric properties(dielectric constantε_(r)=11.36,quality factor Q׃=8245 GHz andε_(r)=9.52,Q׃=22249 GHz)and flexural strengths(200 and 161 MPa),which are expected to be applied in preparation of low temperature co-fired ceramic(LTCC)materials with copper electrodes.Low-temperature sintering of the ZnAl_(2)O_(4)+CTN system is characterized as activated sintering.Nanometer-level amorphous interfacial films containing Cu,Ti,and Nb elements are observed at the grain boundaries,which may provide fast diffusion pathways for mass transportation during the sintering process.Valence changes of Ti and Cu ions,along with changes of oxygen vacancies,are confirmed,which provides a potential mechanism for reduced sintering temperature of ZnAl_(2)O_(4) ceramics.In addition,a series of reactions occurring at the grain boundaries can activate these boundaries and further promote the sintering densification process.These results suggest a promising way to design a novel LTCC material with excellent properties based on the low temperature sintering of ceramics with the sintering aid of CuO-TiO_(2)-Nb_(2)O_(5) composite oxide.
基金supported by the National Natural Science Foundation of China(22178295,21706225)Natural Science Foundation of Hunan Province(2025JJ50085)Hunan Collaborative Innovation Center of New Chemical Technologies for Environmental Benignity and Efficient Resource Utilization.
文摘The new technology of direct decomposition of H_(2)S into high value-added H_(2) and S,as an alternative to the Claus process in industry,is an ideal route that can not only deal with toxic and abundant H_(2)S waste gas but also recover clean energy H_(2),which has significant socio-economic and ecological advantages.However,the highly effective decomposition of H_(2)S at low temperatures is still a great challenge,because of the stringent thermodynamic equilibrium constraints(only 20% even at high temperature of 1010℃).Conventional microwave catalysts exhibit unsatisfactory performance at low temperatures(below 600℃).Herein,Mo_(2)C@CeO_(2) catalysts with a core-shell structure were successfully developed for robust microwave catalytic decomposition of H_(2)S at low temperatures.Two carbon precursors,para-phenylenediamine(Mo_(2)C-p)and meta-phenylenediamine(Mo_(2)C-m),were employed to tailor Mo_(2)C configurations.Remarkably,the H_(2)S conversion of Mo_(2)C-p@CeO_(2) catalyst at a low temperature of 550℃ is as high as 92.1%,which is much higher than the H_(2)S equilibrium conversion under the conventional thermal conditions(2.6% at 550℃).To our knowledge,this represents the most active catalyst for microwave catalytic decomposition of H_(2)S at low temperature of 550℃.Notably,Mo_(2)C-p demonstrated superior intrinsic activity(84%)compared to Mo_(2)C-m(6.4%),with XPS analysis revealing that its enhanced performance stems from a higher concentration of Mo_(2+)active sites.This work presents a substitute approach for the efficient utilization of H_(2)S waste gas and opens up a novel avenue for the rational design of microwave catalysts for microwave catalytic reaction at low-temperature.
