The development of organic frameworks with radical skeletons is desired.In this study,we report the development of a novel two-dimensional radical halogen-bonded organic framework(XOF).The radical monomer,benzimidazol...The development of organic frameworks with radical skeletons is desired.In this study,we report the development of a novel two-dimensional radical halogen-bonded organic framework(XOF).The radical monomer,benzimidazole triphenylmethyl(BTTM),was synthesized through the coupling of TTM radicals with benzimidazole.Initially,the benzimidazole units were coordinated with Ag^(+)ions to create a[N···Ag···N]^(+)framework.Subsequently,the addition of iodine led to the in situ replacement of Ag^(+)with I^(+)ions,forming[N···I···N]^(+)linkers and resulting in the creation of the XOF structure.The resulting XOF-HBTTM and XOF-BTTM structures demonstrated good-crystallinity,confirmed by PXRD,HR-TEM,SEAD,and SAXS analyses.EPR measurements confirmed the preservation of radical characteristics within the XOF framework.Furthermore,SQUID measurements indicated that XOF-BTTM exhibits spin moments of S=1/2 at 2 K,with a saturated magnetization strength peaking at 4.10 emu/g,a notable enhancement compared to 1.87 emu/g for the BTTM monomer.This improvement in magnetism is attributed to the extended spin density distribution and the presence of[N···I···N]^(+)interactions,as suggested by DFT calculations.Additionally,the radical XOF-BTTM exhibited significantly enhanced electrical conductivity,reaching up to 1.30×10^(-4)S/cm,which is two orders of magnitude higher than that of XOF-HBTTM.This increased conductivity is linked to a reduced HOMO-LUMO gap,higher carrier density,and the incorporation of triphenylmethyl radicals within the framework.This research highlights the potential of benzimidazolyl motifs in constructing functional XOFs and advances our understanding of radical organic frameworks.展开更多
Nitrogen use efficiency in rice is lower than in upland crops,likely due to differences in soil nitrogen dynamics and crop nitrogen preferences.However,the specific nitrogen dynamics in paddy and upland systems and th...Nitrogen use efficiency in rice is lower than in upland crops,likely due to differences in soil nitrogen dynamics and crop nitrogen preferences.However,the specific nitrogen dynamics in paddy and upland systems and their impact on crop nitrogen uptake remain poorly understood.The N dynamics and impact on crop N uptake determine the downstream environmental pollution from nitrogen fertilizer.To address this poor understanding,we analyzed 2,044 observations of gross nitrogen transformation rates in soils from 136 studies to examine nitrogen dynamics in both systems and their effects on nitrogen uptake in rice and upland crops.Our findings revealed that nitrogen mineralization and autotrophic nitrification rates are lower in paddies than in upland soil,while dissimilatory nitrate reduction to ammonium is higher in paddies,these differences being driven by flooding and lower total nitrogen content in paddies.Rice exhibited higher ammonium uptake,while upland crops had over twice the nitrate uptake.Autotrophic nitrification stimulated by p H reduced rice nitrogen uptake,while heterotrophic nitrification enhanced nitrogen uptake of upland crops.Autotrophic nitrification played a key role in regulating the ammonium-to-nitrate ratio in soils,which further affected the balance of plant nitrogen uptake.These results highlight the need to align soil nitrogen dynamics with crop nitrogen preferences to maximize plant maximize productivity and reduce reactive nitrogen pollution.展开更多
The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were...The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were performed for the neutron capture cross sections of 159Tb measured at the China Spallation Neutron Source(CSNS)backscattering white neutron beamline(Back-n)facility.The resonance parameters were extracted from the R-Matrix code SAMMY and fitted to the experimental capture yield up to the 1.2 keV resolved resonance region(RRR).The average resonance parameters were determined by performing statistical analysis on the set of the resonance parameters in the RRR.These results were used to fit the measured average capture cross sections using the FITACS code in the unresolved resonance region from 2 keV to 1 MeV.The contributions of partial waves l=0,1,2 to the average capture cross sections are reported.展开更多
We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between e...We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between existing measurements and evaluations of this cross-section.Using an unfolding iteration method,^(63)Cu(γ,n)data were obtained with an uncertainty of less than 4%,and the inconsistencies between the available experimental data were discussed.Theγ-ray strength function of^(63)Cu(γ,n)was successfully extracted as an experimental constraint.We further calculated the cross-section of the radiative neutron capture reaction^(62)Cu(n,γ)using the TALYS code.Our calculation method enables the extraction of(n,γ)cross-sections for unstable nuclides.展开更多
Straw return has demonstrated significant potential for enhancing carbon(C)sequestration and nitrogen(N)uptake while concurrently promoting plant productivity.However,the specific transport and distribution of C produ...Straw return has demonstrated significant potential for enhancing carbon(C)sequestration and nitrogen(N)uptake while concurrently promoting plant productivity.However,the specific transport and distribution of C produced by photosynthesis and exogenous N within the rice plant-soil system under straw return remains unclear.A long-term straw return pot trial experiment was conducted in a double cropping rice system,incorporating treatments of inorganic fertilizer application with straw removal(F),straw burning and ash return with reducing inorganic fertilizers(SBR),and straw return with reducing inorganic fertilizers(SR)to investigate C sequestration and exogenous N uptake using ^(13)C pulse and ^(15)N isotope tracer techniques.The SR treatment had significantly higher soil ^(13)C abundance,by 24.4 and 25.4%,respectively,^(13)C concentrations in aboveground plant parts,by 18.4 and 35.8%respectively,and ^(15)N concentrations in rice panicles,by 12.8 and 34.3%than the SBR and F treatments.This enhancement contributed to a higher total organic C concentration and increased rice grain yield in the SR treatment.Furthermore,the SR treatment had significantly higher photosynthetic C,by 9.8%,which was directly transferred to soil C.The SR treatment had a higher distribution of photosynthetic C in the leaves and stems,but a lower distribution in the panicle compared to the SBR treatment.This finding is advantageous for sequestering photosynthetic C into the soil through straw return;conversely,opposite trends were observed in ^(15)N distribution.In addition,rice plants in the SR treatment had increased N uptake from urea and soil N sources,enhancing N recovery by 9.2 and 12.5%,respectively,and reducing soil N residues.Correlation analysis showed that the SR treatment increased the concentrations of ^(13)C in leaves and roots while decreasing the ^(15)N abundance in all rice organs,thereby contributing to an increase in rice yield.The partial least square path model suggested that the increase in rice yield under the SR treatment was primarily linked to ^(13)C accumulation within the rice plant-soil system.The results suggest that straw return increases the sequestration of photosynthetic C and exogenous N in the rice plant-soil system and increases N utilization efficiency,which subsequently improves both rice and soil productivity.展开更多
This paper extends the previous work[1]for the three-temperature gray radiative transfer equations to the frequency-dependent case.Since the additional frequency variable is considered,the equations are more complicat...This paper extends the previous work[1]for the three-temperature gray radiative transfer equations to the frequency-dependent case.Since the additional frequency variable is considered,the equations are more complicated than those in the gray case.Moreover,opacity may be typically a decreasing function of the frequency variable in applications.At the same spatial location,the equations can be in the optically thick case for low frequency photons,while in the optically thin case for high frequency ones.Thus,the resulting discrete equations can significantly increase the computational cost for opacity having the multi-scale property in multiple frequency radiation.Due to the presence of the radiation-electron coupling,electronion coupling,and electron-ion diffusion terms,the model under consideration exhibits strong nonlinearity and strong coupling properties.In this paper,the multigroup method is used to discretize the frequency variable and the H_(N)^(T)method to discretize the angular variable first.Then,within the framework of a unified gas kinetic scheme(UGKS),a multigroup H_(N)^(T)-UGKS method is constructed to solve this complex model iteratively.Furthermore,it can be shown that as the Knudsen number tends to zero,with variations in the electron-ion coupling,absorption,and scattering coefficients,the multigroup H_(N)^(T)-UGKS scheme can converge to numerical schemes for the single-temperature,two-temperature,and the frequency-dependent three-temperature,two-temperature diffusion limit equations,respectively.Finally,several numerical examples are provided to validate the effectiveness and stability of the proposed scheme.展开更多
基金supported by National Natural Science Foundation of China(Nos.22371218,21702153,52270070 and21801194)Natural Science Foundation of Zhejiang Province(No.LR22B020001)+1 种基金Wuhan Science and Technology Bureau(No.whkxjsj009)the support of the Core Facility of Wuhan University and the Large-scale Instrument and Equipment Sharing Foundation of Wuhan University。
文摘The development of organic frameworks with radical skeletons is desired.In this study,we report the development of a novel two-dimensional radical halogen-bonded organic framework(XOF).The radical monomer,benzimidazole triphenylmethyl(BTTM),was synthesized through the coupling of TTM radicals with benzimidazole.Initially,the benzimidazole units were coordinated with Ag^(+)ions to create a[N···Ag···N]^(+)framework.Subsequently,the addition of iodine led to the in situ replacement of Ag^(+)with I^(+)ions,forming[N···I···N]^(+)linkers and resulting in the creation of the XOF structure.The resulting XOF-HBTTM and XOF-BTTM structures demonstrated good-crystallinity,confirmed by PXRD,HR-TEM,SEAD,and SAXS analyses.EPR measurements confirmed the preservation of radical characteristics within the XOF framework.Furthermore,SQUID measurements indicated that XOF-BTTM exhibits spin moments of S=1/2 at 2 K,with a saturated magnetization strength peaking at 4.10 emu/g,a notable enhancement compared to 1.87 emu/g for the BTTM monomer.This improvement in magnetism is attributed to the extended spin density distribution and the presence of[N···I···N]^(+)interactions,as suggested by DFT calculations.Additionally,the radical XOF-BTTM exhibited significantly enhanced electrical conductivity,reaching up to 1.30×10^(-4)S/cm,which is two orders of magnitude higher than that of XOF-HBTTM.This increased conductivity is linked to a reduced HOMO-LUMO gap,higher carrier density,and the incorporation of triphenylmethyl radicals within the framework.This research highlights the potential of benzimidazolyl motifs in constructing functional XOFs and advances our understanding of radical organic frameworks.
基金funded by the National Key Research and Development Program of China(2024YFD1501602)the National Natural Science Foundation of China(42407437)conducted as part of the Coordinated Research Project D1.50.16,implemented by the Soil and Water Management and Crop Nutrition Section of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture,Department of Nuclear Sciences and Applications,Vienna,Austria。
文摘Nitrogen use efficiency in rice is lower than in upland crops,likely due to differences in soil nitrogen dynamics and crop nitrogen preferences.However,the specific nitrogen dynamics in paddy and upland systems and their impact on crop nitrogen uptake remain poorly understood.The N dynamics and impact on crop N uptake determine the downstream environmental pollution from nitrogen fertilizer.To address this poor understanding,we analyzed 2,044 observations of gross nitrogen transformation rates in soils from 136 studies to examine nitrogen dynamics in both systems and their effects on nitrogen uptake in rice and upland crops.Our findings revealed that nitrogen mineralization and autotrophic nitrification rates are lower in paddies than in upland soil,while dissimilatory nitrate reduction to ammonium is higher in paddies,these differences being driven by flooding and lower total nitrogen content in paddies.Rice exhibited higher ammonium uptake,while upland crops had over twice the nitrate uptake.Autotrophic nitrification stimulated by p H reduced rice nitrogen uptake,while heterotrophic nitrification enhanced nitrogen uptake of upland crops.Autotrophic nitrification played a key role in regulating the ammonium-to-nitrate ratio in soils,which further affected the balance of plant nitrogen uptake.These results highlight the need to align soil nitrogen dynamics with crop nitrogen preferences to maximize plant maximize productivity and reduce reactive nitrogen pollution.
文摘在第四代反应堆的发展中,钍基反应堆(例如钍基熔盐堆)是其中一个重要的研究方向.由于钍的储量大等因素,利用中子诱发^(232)Th发生辐射俘获反应产生^(233)Th是钍基反应堆中的一个重要反应,用于产生易裂变核素^(233)U.本研究采用Monte Carlo方法,定义了一种评价靶材和中子利用效率的综合利用系数,利用多项式拟合得到了综合利用系数和靶材厚度关系,并考虑了不同入射中子数目的影响,最后得到进行此反应的靶材最佳厚度为(1.980±0.002) cm.
基金supported by the National Natural Science Foundation of China(Nos.12365018,U2032146,12465024)Natural Science Foundation of Inner Mongolia(Nos.2023MS01005,2024ZD23,2024FX30)the program of Innovative Research Team and Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(Nos.NMGIRT2217,NJYT23109)。
文摘The neutron capture resonance parameters for 159Tb are crucial for validating nuclear models,nucleosynthesis during the neutron capture process,and nuclear technology applications.In this study,resonance analyses were performed for the neutron capture cross sections of 159Tb measured at the China Spallation Neutron Source(CSNS)backscattering white neutron beamline(Back-n)facility.The resonance parameters were extracted from the R-Matrix code SAMMY and fitted to the experimental capture yield up to the 1.2 keV resolved resonance region(RRR).The average resonance parameters were determined by performing statistical analysis on the set of the resonance parameters in the RRR.These results were used to fit the measured average capture cross sections using the FITACS code in the unresolved resonance region from 2 keV to 1 MeV.The contributions of partial waves l=0,1,2 to the average capture cross sections are reported.
基金supported by the National Key Research and Development Program(Nos.2023YFA1606901 and 2022YFA1602400)National Natural Science Foundation of China(Nos.U2230133,12275338,and 12388102)Open Fund of the CIAE Key Laboratory of Nuclear Data(No.JCKY2022201C152).
文摘We present new data on the^(63)Cu(γ,n)cross-section studied using a quasi-monochromatic and energy-tunableγbeam produced at the Shanghai Laser Electron Gamma Source to resolve the long-standing discrepancy between existing measurements and evaluations of this cross-section.Using an unfolding iteration method,^(63)Cu(γ,n)data were obtained with an uncertainty of less than 4%,and the inconsistencies between the available experimental data were discussed.Theγ-ray strength function of^(63)Cu(γ,n)was successfully extracted as an experimental constraint.We further calculated the cross-section of the radiative neutron capture reaction^(62)Cu(n,γ)using the TALYS code.Our calculation method enables the extraction of(n,γ)cross-sections for unstable nuclides.
基金supported by the National Natural Science Foundation of China(32160503)the Earmarked Fund for Jiangxi Agriculture Research System,China(JXARS-01)the National Key R&D Program of China(2023YFD2301303).
文摘Straw return has demonstrated significant potential for enhancing carbon(C)sequestration and nitrogen(N)uptake while concurrently promoting plant productivity.However,the specific transport and distribution of C produced by photosynthesis and exogenous N within the rice plant-soil system under straw return remains unclear.A long-term straw return pot trial experiment was conducted in a double cropping rice system,incorporating treatments of inorganic fertilizer application with straw removal(F),straw burning and ash return with reducing inorganic fertilizers(SBR),and straw return with reducing inorganic fertilizers(SR)to investigate C sequestration and exogenous N uptake using ^(13)C pulse and ^(15)N isotope tracer techniques.The SR treatment had significantly higher soil ^(13)C abundance,by 24.4 and 25.4%,respectively,^(13)C concentrations in aboveground plant parts,by 18.4 and 35.8%respectively,and ^(15)N concentrations in rice panicles,by 12.8 and 34.3%than the SBR and F treatments.This enhancement contributed to a higher total organic C concentration and increased rice grain yield in the SR treatment.Furthermore,the SR treatment had significantly higher photosynthetic C,by 9.8%,which was directly transferred to soil C.The SR treatment had a higher distribution of photosynthetic C in the leaves and stems,but a lower distribution in the panicle compared to the SBR treatment.This finding is advantageous for sequestering photosynthetic C into the soil through straw return;conversely,opposite trends were observed in ^(15)N distribution.In addition,rice plants in the SR treatment had increased N uptake from urea and soil N sources,enhancing N recovery by 9.2 and 12.5%,respectively,and reducing soil N residues.Correlation analysis showed that the SR treatment increased the concentrations of ^(13)C in leaves and roots while decreasing the ^(15)N abundance in all rice organs,thereby contributing to an increase in rice yield.The partial least square path model suggested that the increase in rice yield under the SR treatment was primarily linked to ^(13)C accumulation within the rice plant-soil system.The results suggest that straw return increases the sequestration of photosynthetic C and exogenous N in the rice plant-soil system and increases N utilization efficiency,which subsequently improves both rice and soil productivity.
基金supported by the Beijing Natural Science Foundation(Z230003)for Sunby the National Key R&D Program(2020YFA0712200)+1 种基金the National Key Project(GJXM92579)the Sino-German Science Center(GZ 1465)for Jiang。
文摘This paper extends the previous work[1]for the three-temperature gray radiative transfer equations to the frequency-dependent case.Since the additional frequency variable is considered,the equations are more complicated than those in the gray case.Moreover,opacity may be typically a decreasing function of the frequency variable in applications.At the same spatial location,the equations can be in the optically thick case for low frequency photons,while in the optically thin case for high frequency ones.Thus,the resulting discrete equations can significantly increase the computational cost for opacity having the multi-scale property in multiple frequency radiation.Due to the presence of the radiation-electron coupling,electronion coupling,and electron-ion diffusion terms,the model under consideration exhibits strong nonlinearity and strong coupling properties.In this paper,the multigroup method is used to discretize the frequency variable and the H_(N)^(T)method to discretize the angular variable first.Then,within the framework of a unified gas kinetic scheme(UGKS),a multigroup H_(N)^(T)-UGKS method is constructed to solve this complex model iteratively.Furthermore,it can be shown that as the Knudsen number tends to zero,with variations in the electron-ion coupling,absorption,and scattering coefficients,the multigroup H_(N)^(T)-UGKS scheme can converge to numerical schemes for the single-temperature,two-temperature,and the frequency-dependent three-temperature,two-temperature diffusion limit equations,respectively.Finally,several numerical examples are provided to validate the effectiveness and stability of the proposed scheme.
