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Biochar amendment affects soil nitrogen transformation and nitrous oxide emission:A15N tracer study 认领 引用
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作者 Jie ZHANG Ping HE +5 位作者 Liang JIN Dan WEI Xinpeng XU Shicheng ZHAO Wei ZHOU Shaojun QIU 《Pedosphere》 SCIE CAS CSCD 2026年第2期595-602,共8页
Biochar amendment is considered a potential strategy to improve soil fertility and mitigate climate change,yet its specific effects on the fate of fertilizer-derived and native soil nitrogen remain unclear.To elucidat... Biochar amendment is considered a potential strategy to improve soil fertility and mitigate climate change,yet its specific effects on the fate of fertilizer-derived and native soil nitrogen remain unclear.To elucidate the effect of biochar amendment on soil nitrogen(N)transformation and nitrous oxide(N2O)emission,a 56-d soil incubation experiment was conducted using15N isotope tracing to monitor the fate of N.Three treatments were set up:ⅰ)no addition of N or biochar control(CK),ⅱ)addition of15N-labeled ammonium sulfate((NH4)2SO4)(NS),andⅲ)combined addition of15N-labeled(NH4)2SO4and biochar(NS+BC).The15N abundances in soil ammonium(NH4+),nitrate(NO3-),microbial biomass N(MBN),particulate organic N(PON),mineral-associated total N(MTN),and N2O were measured.Compared with NS,endogenous soil N-derived NH4+-N and N2O decreased significantly by 34.4%-67.6% and 18.3%-51.2%,respectively,and exogenous N-derived NH4+-N,MTN,and N2O decreased significantly by 49.6%-81.4%,15.0%-47.0%,and 42.3%-76.5%,respectively,in NS+BC during the first 14 d.Biochar amendment significantly increased endogenous and exogenous soil N retention in MBN by 16.7%-40.1% and over 200 times,respectively,during the first 21 d.The endogenous and exogenous soil N retention in PON increased by12.5%-27.0% and 18.2%-78.5%,respectively,over the whole incubation period.For MTN,the endogenous and exogenous soil N retention increased by 3.9%-6.1% and 24.9%-30.6%,respectively,from days 21 to 56.The contribution of endogenous N to the total N2O emission was>80% across treatments.These results show that biochar amendment can mitigate soil N2O emission and promote inorganic N translocation into MBN,PON,and MTN in soil. 展开更多
关键词 endogenous N exogenous N microbial biomass N mineral-associated total N 15N isotope tracing particulate organic N soil N pool
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氮肥分期调控对黔湄601单芽产量及15N-肥料吸收利用特性的影响 认领 引用
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作者 王静 席亚楠 +5 位作者 曾廷廷 何开峰 王家伦 雷春兰 代文典 张小琴 《核农学报》 CAS CSCD 北大核心 2026年第2期356-364,共9页
为促进黔湄601全年采摘单芽茶园氮肥高效利用,本研究采用田间15N示踪技术,测定不同氮肥分期模式对新梢产量、氮积累量以及15N-肥料吸收利用特征的影响。结果表明,“一基一追”模式的新梢产量和氮积累量最高。由于“一基三追”模... 为促进黔湄601全年采摘单芽茶园氮肥高效利用,本研究采用田间15N示踪技术,测定不同氮肥分期模式对新梢产量、氮积累量以及15N-肥料吸收利用特征的影响。结果表明,“一基一追”模式的新梢产量和氮积累量最高。由于“一基三追”模式秋季15N-追肥在次年春茶中的吸收量较高,其15N-肥料累计吸收利用效率也高于“一基一追”和“一次追肥”模式。但是,“加入氮交互效应”在一定程度上影响了新梢对土壤氮与肥料氮的选择性吸收,促使“一基一追”模式在15N-肥料累计吸收量较低的情况下,其总氮积累量反而高于“一基三追”模式。新梢对各次15N-肥料的最大吸收茶季与相应施肥日期的间隔较长(78~274 d),可长达一个茶季。相应地,施入茶园的氮肥需要经过足够长的时间甚至一个茶季,才能在新梢产量和氮积累量上呈现出明显肥效。综上,“一基一追”模式是黔湄601单芽采摘制度下促进新梢高产高氮积累的氮肥分期模式。本研究结果可为地方黔茶品种氮高效利用提供科学依据,并有助于丰富茶园供氮理论体系。 展开更多
关键词 15N示踪 氮肥 分期调控 茶树
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Contrasting NH4+and NO3−uptake preference between woody and herbaceous plants in Chinese terrestrial ecosystems 认领 引用
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作者 Lina Wang Ying Zhou +4 位作者 Hao Lu Jing Bai Jiayin Liu Gaolin Wu Yakun Tang 《Journal of Forestry Research》 SCIE EI CAS CSCD 2026年第3期229-242,共14页
Different plants exist in preferences for ammonium(NH4+)and nitrate(NO3−)as the dominant N source,reflecting their adaptation to habitat environments.Elucidating plant specific nitrogen preferences and inf... Different plants exist in preferences for ammonium(NH4+)and nitrate(NO3−)as the dominant N source,reflecting their adaptation to habitat environments.Elucidating plant specific nitrogen preferences and influencing factors is crucial for ecosystem management under climate change.In this study,we synthesized 216 observations from15N isotopic tracer studies of diverse forests and grasslands in China to elucidate variations in and factors influencing soil inorganic nitrogen uptake by woody and herbaceous plants.Woody plants had significantly higher uptake rates and proportional contributions of15NH4+than15NO3−(P<0.05),while herbaceous plants exhibited a contrary trend(P<0.05).Mean annual temperature played a significantly role in regulating both15NH4+and15NO3−uptake rates in woody and herbaceous plants,followed by mean annual precipitation,mean annual inorganic nitrogen deposition rates,and soil total nitrogen content(P<0.05).In addition,the key factors influencing nitrogen preference of woody and herbaceous plants were woody plant functional types(evergreen and deciduous plants)and soil inorganic nitrogen content,respectively.Based on the different functional types of woody plants,evergreen plants preferred15NH4+,while deciduous plants preferred15NO3−.The results reveal inorganic nitrogen patterns by different plant types in China and that mean annual temperature is a key determinant of plant nitrogen uptake rates.Thus,by matching species-specific nitrogen preferences with the environmental conditions of different regions,valuable insights can be gained to improve the uptake of inorganic N by different plant types and cope with N limitation. 展开更多
关键词 Nitrogen deposition Nitrogen preference 15N isotopic tracer Plant functional type
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Parallel denitrification and nitrite oxidation in the unsaturated zone: Isotopic constraints from nitrate δ15N and δ18O in Tianjin, China 认领 引用
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作者 Dongmei Xue Jinglei Wang +6 位作者 Lanxin Xiang Xiaoxian Peng Ke Jin Yunting Fang Xiangzhen Li Yidong Wang Zhongliang Wang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2026年第6期2580-2594,共15页
Denitrification plays a critical role in mitigating anthropogenic nitrate(NO3-) accumulation in ecosystems.The isotopic composition of NO3-(δ15N and δ18O) serves as a powerful tracer for identifyin... Denitrification plays a critical role in mitigating anthropogenic nitrate(NO3-) accumulation in ecosystems.The isotopic composition of NO3-(δ15N and δ18O) serves as a powerful tracer for identifying N sources and transformation processes.Denitrification often superimposed on the isotope effects of NO2- oxidation, resulting in parallel enrichment of δ15N-and δ18O-NO3-(Δδ18O:Δδ15N trajectory) that causes them to be either below or above 1.This study compared the Δδ18O:Δδ15N trajectory during denitrification, functional genes(nar G, nap A, and nxr A), and carbon sources from metabolites in the Δδ18O:Δδ15N trajectories below or above 1 in unsaturated zones.The results revealed that NO3- reduction was more important for variation in the Δδ18O:Δδ15N trajectory because the difference in isotope effects(15ε_(NO_(3 reduction)) and 18ε_(NO_(3 reduction))) between the two Δδ18O:Δδ15N trajectory groups was significant, whereas the difference in isotope effects(15εnxr and 18εnxr) upon NO2- oxidation was not.Carbon sources in the group with Δδ18O:Δδ15N trajectories below 1 facilitated more efficient electron production to promote NO3- reduction because of their low molecular weight and simple structure.Conversely, the lower electron production efficiency due to the high molecular weight and complex structures of carbon sources in the group with Δδ18O:Δδ15N trajectories above 1 downregulated the expression of the three functional genes(nar G, nap A, and nxr A).The group with Δδ18O:Δδ15N trajectories below 1 showed significantly higher levels of 15ε_(NO_(3 reduction)), 18ε_(NO_(3 reduction)), NO2- oxidation ratio, and copy numbers of nar G, nap A, and nxr A genes compared to the other group, revealing that NO3- reduction at the cellular level was more active in the former group.This study elucidated the integrated infiuence of isotope effects, NO3- reductase and NO2- oxidoreductase activities, and carbon sources from metabolites.These findings are significant for understanding the Δδ18O:Δδ15N trajectories of N cycling in terrestrial ecosystems and support groundwater conservation by improving carbon supplementation approaches that stimulate denitrification, with Δδ18O:Δδ15N trajectories serving as effective tracers for assessing denitrification performance in terrestrial environments. 展开更多
关键词 denitrification NO2-oxidation Δδ18O:Δδ15N trajectory NO3-reductase NO2-oxidoreductase carbon sources
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15N标记同位素在一氧化二氮合成机理中的应用 认领 引用
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作者 刘占峰 徐建飞 +4 位作者 宋明鸣 侯莉婷 郭王王 叶展宏 岳海艳 《化学世界》 CAS 2026年第3期168-171,共4页
一氧化二氮是一种既有利也有害的气体,在亚硝酸钠与盐酸羟胺合成一氧化二氮的方法中,无法确定一氧化二氮中每个氮的具体来源.利用15N标记的亚硝酸钠为原料,与盐酸羟胺反应,确定了合成的产物为15N标记的一氧化二氮(N15NO),其中... 一氧化二氮是一种既有利也有害的气体,在亚硝酸钠与盐酸羟胺合成一氧化二氮的方法中,无法确定一氧化二氮中每个氮的具体来源.利用15N标记的亚硝酸钠为原料,与盐酸羟胺反应,确定了合成的产物为15N标记的一氧化二氮(N15NO),其中连接O的N来源于亚硝酸钠,另一个N来源于盐酸羟胺,经实验验证推断正确.为后续获得不同标记位置的15N标记的一氧化二氮奠定基础. 展开更多
关键词 15N标记亚硝酸钠 同位素 一氧化二氮
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Construction of radical halogen-bonded organic frameworks with enhanced magnetism and conductivity 认领 引用 被引量：2
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作者 Hong-Qiang Dong Shang-Bo Yu +9 位作者 Shu-Meng Wang Jia-Hao Zhao Xu-Guan Bai Shi-Xing Lei Zhen-Nan Tian Jia Tian Kang-Da Zhang Lu Wang Zhan-Ting Li Shigui Chen 《Chinese Chemical Letters》 SCIE CAS CSCD 2025年第8期331-336,共6页
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 1.30×10-4S/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
关键词 [N...I...N%0X005D%+Halogen-bonded organic framework Radical Paramagnetic Hall effect
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土壤浸提液中自然丰度和低浓度标记NH4+-15N测定方法优化 认领 引用
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作者 游志洁 叶平 +3 位作者 张思苇 戴沈艳 温腾 张金波 《土壤学报》 CAS CSCD 北大核心 2026年第3期905-916,共12页
土壤铵态氮(NH4+-N)的15N同位素比值在氮转化研究中具有重要的应用价值。扩散法作为分离转化土壤NH4+-N的最有效方法,其在低浓度标记丰度、自然丰度NH4+-N上的应用仍有限。通过优化酸阱材料及制作方法、培养时间... 土壤铵态氮(NH4+-N)的15N同位素比值在氮转化研究中具有重要的应用价值。扩散法作为分离转化土壤NH4+-N的最有效方法,其在低浓度标记丰度、自然丰度NH4+-N上的应用仍有限。通过优化酸阱材料及制作方法、培养时间、反应体积和培养温度,探讨仅使用扩散法转化、测定低浓度(≤1 mg·L–1)标记和自然丰度NH4+-15N的可行性。结果发现:(1)使用价格低廉的纯聚四氟乙烯(PTFE)膜并改进制作方式的扩散包式酸阱不仅降低成本、操作简便,且提高回收率至99.8%。(2)扩散法可准确、灵敏测定低至0.2 mg·L–1的标记NH4+-15N丰度,误差低于0.060 atom%,经校正后与理论值差距小于0.020 atom%;单独使用扩散法也能准确、灵敏测定大于等于1 mg·L–1的自然丰度NH4+-15N,误差小于等于0.30‰,测定值与理论值的差距小于0.38‰;更低浓度的标记或自然丰度NH4+-15N需将扩散法与其他方法结合。(3)加温虽能有效缩短扩散时间,提高回收率,却也增大了杂质氮和可溶性有机氮的干扰,在实际测定中需谨慎使用。扩散法仍然是转化、测定土壤中NH4+-15N丰度的有力方法,改进后的扩散法可用于不同浓度、丰度的NH4+-15N测定。 展开更多
关键词 扩散法 土壤NH4+-15N 标记丰度 自然丰度 低浓度
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Soil nitrogen dynamics regulate differential nitrogen uptake between rice and upland crops 认领 引用
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作者 Shending Chen Ahmed S.Elrys +5 位作者 Siwen Du Wenyan Yang Zucong Cai Jinbo Zhang LeiMeng Christoph Müller 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2026年第1期302-312,共11页
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
关键词 paddy soil upland soil plant nitrogen uptake N mineralization nitrification 15N tracing study
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New measurement of 63Cu(γ,n)62Cu cross-section using quasi-monoenergeticγ-ray beam 认领 引用 被引量：2
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作者 Zhi-Cai Li Zi-Rui Hao +16 位作者 Qian-Kun Sun Yu-Long Shen Long-Xiang Liu Hang-Hua Xu Yue Zhang Pu Jiao Meng-Die Zhou Yu-Xuan Yang Sheng Jin Kai-Jie Chen Zhen-Wei Wang Shan Ye Xin-Xiang Li Chun-Wang Ma Hong-Wei Wang Gong-Tao Fan Wen Luo 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2025年第2期131-140,共10页
We present new data on the63Cu(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 the63Cu(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,63Cu(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 of63Cu(γ,n)was successfully extracted as an experimental constraint.We further calculated the cross-section of the radiative neutron capture reaction62Cu(n,γ)using the TALYS code.Our calculation method enables the extraction of(n,γ)cross-sections for unstable nuclides. 展开更多
关键词 63Cu(γ n)reaction Cross-section data Quasi-monochromaticbeam Radiative neutron capture reaction
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基于15N示踪技术的甘蔗不同季节播种对氮肥利用效率影响研究 认领 引用 被引量：1
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作者 韦剑锋 韦冬萍 +5 位作者 胡桂娟 罗小芬 吴炫柯 胡文莉 黄锴霖 马纪 《核农学报》 CAS CSCD 北大核心 2025年第2期369-376,共8页
为促进甘蔗(Saccharum spp.)氮肥高效利用,以甘蔗品种桂糖42号为材料,采用田间微区15N示踪技术分析秋季(8月20日)、春季(2月20日)和夏季(5月20日)播种甘蔗的氮肥利用效率及去向。结果表明,3个播期新植蔗吸收的N有21.56%~33.93%来自... 为促进甘蔗(Saccharum spp.)氮肥高效利用,以甘蔗品种桂糖42号为材料,采用田间微区15N示踪技术分析秋季(8月20日)、春季(2月20日)和夏季(5月20日)播种甘蔗的氮肥利用效率及去向。结果表明,3个播期新植蔗吸收的N有21.56%~33.93%来自当季施用的氮肥,氮肥利用率、残留率和损失率分别为16.84%~21.50%、42.71%~47.45%和31.05%~39.43%;宿根蔗吸收的N来自上季施用氮肥的比率为6.65%~9.16%,上季氮肥在宿根季的利用率、残留率和损失率分别为4.15%~6.58%、30.25%~31.26%和8.31%~9.61%。3个播期两季甘蔗氮肥残留均随土层深度的增加而大幅递减,但0~40 cm土层残留以夏季播种较多,40~60 cm土层残留以秋季播种较多。秋季播种两季蔗茎干物质积累量为59693.69 kg·hm-2,较春季、夏季播种增加2.74%和34.43%;夏季播种两季甘蔗的氮肥利用率为28.08%,较秋季、春季播种提高4.63和6.58个百分点;春季播种两季甘蔗的氮肥损失率为47.85%,较秋季、夏季播种增加1.54和7.19个百分点。可见,甘蔗秋季播种产量较高,夏季播种氮肥吸收较多、损失较少,但夏季播种新植蔗吸收的大量氮肥未能转化为增产效应。本研究结果可为优化广西甘蔗氮肥施用提供科学依据。 展开更多
关键词 甘蔗 播种期 15N示踪 氮肥利用 氮素残留
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瞬时NH4+—N冲击后投加碳源对系统稳定运行的影响 认领 引用 被引量：1
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作者 王帆 崔秦 +3 位作者 蒋维卿 刘轩彤 艾胜书 边德军 《东北师大学报（自然科学版）》 CAS 北大核心 2025年第2期151-156,共6页
为解决实际工程中序批式活性污泥法(SBR)工艺出现的瞬时NH4+—N冲击导致运行不稳定问题,通过单周期瞬时高浓度NH4+—N冲击试验,探究了瞬时高浓度NH4+—N冲击对SBR工艺的影响;采用投加碳源的方式应对冲击,并确定了最... 为解决实际工程中序批式活性污泥法(SBR)工艺出现的瞬时NH4+—N冲击导致运行不稳定问题,通过单周期瞬时高浓度NH4+—N冲击试验,探究了瞬时高浓度NH4+—N冲击对SBR工艺的影响;采用投加碳源的方式应对冲击,并确定了最适碳源投加量.结果表明,系统经过瞬时高浓度NH4+—N冲击后,C/N比从8.5下降到3.9,碳源不足影响反硝化效果,TN和NH4+—N出水浓度升高.通过投加有机物改变进水C/N比的方式对系统进行调控,当C/N比增加至6.1时,TP去除效果变化显著,并能在1.5 h实现完全去除,出水浓度为0.11 mg/L;当C/N比增至8.3时,NH4+—N去除率明显提高,出水为3.76 mg/L;当C/N比增至10.5时,COD降解速率达到151.90 mg/(L·h),TP浓度在单周期运行前期呈大幅度的上升趋势,在后期完全去除.3种有机物投加量下出水COD、NH4+—N、TN、TP浓度值均能达标.SBR在面临瞬时NH4+—N冲击C/N比下降至3.9时,最适碳源投加量选用C/N比为8.3,经济成本较低且处理效果最好. 展开更多
关键词 瞬时NH4+—N冲击 脱氮除磷 去除率 C/N比 投加碳源
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Quantitative assessment of the transport and distribution of photosynthetic carbon and exogenous nitrogen in a rice-soil system under long-term straw return:An isotope trial using 13C and 15N labelling 认领 引用 被引量：1
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作者 Shiqi Yang Liming Chen +4 位作者 Yifan Tang Xueming Tan Yongjun Zeng Xiaohua Pan Yanhua Zeng 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2025年第10期4063-4077,共15页
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 13C pulse and 15N isotope tracer techniques.The SR treatment had significantly higher soil 13C abundance,by 24.4 and 25.4%,respectively,13C concentrations in aboveground plant parts,by 18.4 and 35.8%respectively,and 15N 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 15N 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 13C in leaves and roots while decreasing the 15N 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 13C 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
关键词 long-term straw return 13C pulse labelling 15N isotope tracer rice plant-soil system photosynthetic C nitrogen utilization efficiency
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Resonance analysis of159Tb(n,γ)reaction based on the CSNS Back-n experiment 认领 引用 被引量：1
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作者 De-Xin Wang Su-Ya-La-Tu Zhang +14 位作者 Wei Jiang Jie Ren Mei-Rong Huang Jing-Yu Tang Xi-Chao Ruan Hong-Wei Wang Long-Xiang Liu Xue Li Dan-Dan Niu Guo Li Gu-Fu Meng Yong-Shun Huang Zhi-Long Wang Yu Bai Xue Yang 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2025年第3期85-94,共10页
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
关键词 Statistical analysis Resonance parameters 159Tb(n,γ)cross section γ
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Mg3Bn0/-(n=1~8)团簇几何结构、稳定性和特性研究 认领 引用
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作者 李成刚 赵海涛 +2 位作者 田浩 滕达 申梓刚 《北京化工大学学报（自然科学版）》 CAS CSCD 北大核心 2025年第3期55-64,共10页
基于卡利普索结构预测程序和密度泛函理论,系统地研究了Mg3Bn0/-(n=1~8)团簇的几何结构、稳定性和特性。首先,基于CCSD(T)/aug-cc-pvdz//B3LYP/6-311+G(d)下单点能的计算,Mg3B3-和Mg3B4-团簇全局极小结构具... 基于卡利普索结构预测程序和密度泛函理论,系统地研究了Mg3Bn0/-(n=1~8)团簇的几何结构、稳定性和特性。首先,基于CCSD(T)/aug-cc-pvdz//B3LYP/6-311+G(d)下单点能的计算,Mg3B3-和Mg3B4-团簇全局极小结构具有平面二维结构,其他团簇均呈现三维结构。当n=3、6、8时,中性和阴性团簇分别具有相同的对称性结构。其次,基于平均键能、二阶能量差分和HOMO-LUMO能隙分析,Mg3B6和Mg3B7-团簇在各自体系中具有相对高的稳定性。电荷和键级分析表明,电荷由镁原子向硼原子转移,B-B之间作用均为共价键,硼原子的加入削弱了镁原子之间的作用力。基于Multiwfn软件,拟合出了体系的光电子能谱、红外和拉曼光谱。最后,通过对Mg3B6和Mg3B7-团簇的热力学特性分析发现,随着温度升高,定容热容和标准熵随之增大,温度和两者之间分别存在近似二次函数关系。 展开更多
关键词 Mg3Bn0/-(n=1~8)团簇 卡利普索 几何结构 特性
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北京典型绿化乔木对PM2.5无机成分NH4+和NO3-的吸收和分配机制 认领 引用
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作者 房佳兴 李少宁 +9 位作者 柴硕 赵娜 徐晓天 李斌 张俊杰 王梦雪 张琴 刘辰 吕金昊 鲁绍伟 《生态学报》 CAS CSCD 北大核心 2025年第2期837-853,共17页
植物能有效吸收大气中PM2.5改善空气质量,探明其吸收和分配PM2.5机理对提高植物生态功能和改善生态环境意义重大。利用一次性熏气法结合15N示踪法探究北京典型绿化乔木油松(Pinus tabuliformis)、白皮松(Pinus bungeana)、旱柳... 植物能有效吸收大气中PM2.5改善空气质量,探明其吸收和分配PM2.5机理对提高植物生态功能和改善生态环境意义重大。利用一次性熏气法结合15N示踪法探究北京典型绿化乔木油松(Pinus tabuliformis)、白皮松(Pinus bungeana)、旱柳(Salix matsudana)、银杏(Ginkgo biloba)、国槐(Styphnolobium japonicum)和栾树(Koelreuteria paniculata)对PM2.5水溶性无机成分NH4+和NO3-吸收与分配特征。结果表明:(1)植物能有效吸收PM2.5中NH4+(0.03—0.80μg/g)和NO3-(0.02—1.10μg/g)。对NH4+吸收能力表现为旱柳和油松最强,其次是银杏和栾树,白皮松和国槐最弱;对NO3-吸收能力表现为旱柳和油松最强,其次是白皮松和国槐,栾树和银杏最弱。(2)植物地上器官15N吸收能力和分配率大于地下器官。叶片对两种离子的吸收能力(NH4+:0.08—1.63μg/g,NO3-:0.01—1.18μg/g)和分配率(NH4+:18.95%—76.10%,NO3-:6.86%—91.64%)最高。(3)不同浓度、树种及二者交互作用显著影响各器官15N吸收能力和分配率(P<0.01),其中地上器官吸收能力随浓度升高而增加。(4)具有较小根冠比、粗根生物量比和较大枝生物量比特征的植物更利于吸收NH4+;具有较小根冠比、粗细根生物量比和较大干生物量比特征的植物更利于吸收NO3-。研究结果进一步揭示植物吸收PM2.5机制及其与自身因素(植物性状)和自然因素(PM2.5浓度)的关系,对不同污染程度地区如何有效利用植物净化PM2.5污染提供科学依据。 展开更多
关键词 典型绿化乔木 一次性熏气法 15N示踪 PM2.5无机成分 吸收与分配
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衰老抑制C57BL/6J小鼠肺部CD8+T细胞对甲型H1N1流感病毒的记忆性免疫应答 认领 引用
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作者 王超 李顺 +4 位作者 任晓楠 杨华 陈丽香 徐春华 周晓辉 《实验动物与比较医学》 CAS 2025年第5期515-523,共9页
目的比较年轻与老年C57BL/6J小鼠感染甲型H1N1流感病毒后肺组织中CD8+T细胞在收缩期及记忆性免疫应答期的功能差异。方法摘取未行流感病毒感染的年轻(3月龄)与老年(24月龄)雌性C57BL/6J小鼠肺组织,制备单细胞悬液,分别用佛波酯(phorb... 目的比较年轻与老年C57BL/6J小鼠感染甲型H1N1流感病毒后肺组织中CD8+T细胞在收缩期及记忆性免疫应答期的功能差异。方法摘取未行流感病毒感染的年轻(3月龄)与老年(24月龄)雌性C57BL/6J小鼠肺组织,制备单细胞悬液,分别用佛波酯(phorbol 12-myristate 13-acetate,PMA)/离子霉素或分化簇(cluster of differentiation,CD)3/CD28抗体(T细胞抗原受体/共刺激信号)进行非特异性抗原刺激,通过流式细胞术对肺CD8+T细胞行细胞内细胞因子染色(flow cytometry intracellular cytokine staining,ICS)以检测其分泌肿瘤坏死因子-α(tumornecrosisfactor-α,TNF-α)和干扰素-γ(interferon-γ,IFN-γ)的能力。以490 PFUPR8流感病毒滴鼻感染年轻和老年C57BL/6J小鼠,28天后进行同源流感病毒的二次感染,于初次感染后第28天(收缩期)、第32天(记忆性免疫应答期)分离肺组织,采用流感病毒特异性MHC-Ⅰ四聚体染色法检测病毒特异性CD8+T细胞在肺组织CD8+T细胞中的比例,ICS法分析CD8+CD44high T细胞亚群TNF-α、IFN-γ及颗粒酶B(granzyme B)的表达。结果非特异性抗原刺激后,老年组小鼠的肺组织CD8+T细胞中TNF-α、IFN-γ分泌能力显著高于年轻组(P0.05);而在记忆性免疫应答期,老年组小鼠的病毒特异性CD8+T细胞比例以及TNF-α、IFN-γ、granzymeB的表达水平均显著低于年轻组(P<0.05)。结论老年小鼠肺部CD8+T细胞在非特异性抗原刺激下免疫相关因子表达功能正常,但在抗原特异性记忆免疫应答阶段的免疫相关因子表达功能受损,提示衰老导致CD8+T细胞免疫记忆形成或维持发生缺陷。 展开更多
关键词 甲型H1N1流感病毒 CD8+T细胞 免疫衰老 记忆性免疫应答 小鼠
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哀牢山亚热带森林附生维管植物δ15N特征及分馏效应 认领 引用
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作者 周春艳 苏天昊 +3 位作者 刘彦 普晓妍 鲁志云 李苏 《热带亚热带植物学报》 CAS CSCD 北大核心 2025年第5期495-502,共8页
叶片氮(N)同位素组成(δ15N)的自然变化被用于研究附生维管植物的N获取和利用策略,但植物在N吸收、转运和同化过程中发生的15N分馏效应往往会影响基于15N自然丰度法的研究结果的可靠性。而附生植物体内是否发生15N分馏效应... 叶片氮(N)同位素组成(δ15N)的自然变化被用于研究附生维管植物的N获取和利用策略,但植物在N吸收、转运和同化过程中发生的15N分馏效应往往会影响基于15N自然丰度法的研究结果的可靠性。而附生植物体内是否发生15N分馏效应并导致不同器官间δ15N差异,以及叶片δ15N是否能够作为全株δ15N的可靠代用指标仍不明晰。该研究以哀牢山亚热带常绿阔叶林的附生植物为研究对象,分析了附生植物全株和各器官的δ15N变化特征,以及器官间δ15N差值与其他性状的关系。结果表明,附生植物叶片(–3.48‰)、茎(–3.47‰)、根(–2.25‰)的δ15N均为负值,表明其主要依赖于大气沉降的15N贫化N源。除长叶粗筒苣苔(Oreocharis longifolia)外,其余附生植物[距药姜(Cautleya gracilis)、棕鳞瓦韦(Lepisorus scolopendrium)、毛唇独蒜兰(Pleione hookeriana)]体内叶-根(∆15Nleaf–root:–1.23‰)、叶-茎(∆15Nleaf–stem:–0.62‰)、茎-根(∆15Nstem–root:–1.10‰)间均表现出显著的N同位素分馏效应,但通常弱于陆生植物。此外,附生植物叶-根15N分馏值与叶δ13C(r=–0.57;P<0.01)、根δ13C(r=–0.57,–0.50;P<0.05)均显著负相关,可能暗示其对水分亏缺高度敏感。附生维管植物叶片δ15N与全株δ15N显著相关(R2 adj.=0.526,P<0.01),证实叶片δ15N可以作为全株δ15N的代用指标。这为利用叶片δ15N探讨附生植物氮获取策略及其生态适应机制提供了重要依据。 展开更多
关键词 附生维管植物 亚热带森林 氮同位素自然丰度(δ15N) 15N分馏 N营养 水分胁迫
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A HNT-UGKS SCHEME FOR THE THREE-TEMPERATURE FREQUENCY-DEPENDENT RADIATIVE TRANSFER EQUATIONS 认领 引用
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作者 Qi LI Wenjun SUN Song JIANG 《Acta Mathematica Scientia》 SCIE CSCD 2025年第6期2391-2420,共30页
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 HNTmethod to discretize the angular variable first.Then,within the framework of a unified gas kinetic scheme(UGKS),a multigroup HNT-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 HNT-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
关键词 frequency-dependent radiative transfer three-temperature model HNTmethod unified gas kinetic scheme asymptotic preserving property
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15N稳定同位素技术在陆地生态系统生物固氮研究中的应用 认领 引用
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作者 陈美凤 高英志 《应用生态学报》 CAS CSCD 北大核心 2025年第7期1952-1960,共9页
生物固氮(BNF)是陆地生态系统氮素的重要来源,准确估算生物固氮速率对精确量化大气氮输入自然生态系统的总氮量至关重要。15N自然丰度法常用于测定野外共生和联合固氮植物的固氮速率,但高度依赖参考植物的选择。15N稳定同位素标... 生物固氮(BNF)是陆地生态系统氮素的重要来源,准确估算生物固氮速率对精确量化大气氮输入自然生态系统的总氮量至关重要。15N自然丰度法常用于测定野外共生和联合固氮植物的固氮速率,但高度依赖参考植物的选择。15N稳定同位素标记技术不仅能精确测定共生、自生和联合型3种类型的固氮速率,还有助于深入研究生物固氮策略、氮转移过程以及根瘤与宿主之间的碳氮交换关系。其中15N同位素稀释法主要用于植物固氮研究,而15N稳定同位素探针技术尽管操作繁琐且成本较高,但通过标记DNA或RNA能用于固氮微生物的功能研究以及有效测定非共生微生物固氮速率。15N稳定同位素技术的发展能为生物固氮研究提供强有力的技术保障。 展开更多
关键词 15N同位素 固氮菌 标记 微生物 自然丰度法
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A Type of Halogen-Bonded Organic Frameworks Based on N…Cl+…N Bonds: Stabilizing Sensitive Species 认领 引用
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作者 Xuguan Bai Zhennan Tian +12 位作者 Hongqiang Dong Jiahao Zhao Qiaoyan Qi Shixing Lei Mao Sun Min Wei Jianrong Zeng Shangming He Jia Tian Lu Wang Jike Wang Haohu Li Shigui Chen 《CCS Chemistry》 CSCD 2026年第5期2583-2596,共14页
It remains a significant challenge to explore halogen bonds(XB)based on chlorine,despite extensive investigation into those involving larger halogen atoms like iodine and bromine.The[N…Cl…N]+ halogen bond is usua... It remains a significant challenge to explore halogen bonds(XB)based on chlorine,despite extensive investigation into those involving larger halogen atoms like iodine and bromine.The[N…Cl…N]+ halogen bond is usually unstable and typically only obtainable at extremely low temperatures(approximately−80℃)due to chlorine’s high electronegativity.In this work,we demonstrated the inaugural construction of stable chlorine(Ⅰ)-bridged two-dimensional halogen-bonded organic frameworks(XOFs)utilizing sensitive[N…Cl…N]+ XB.The formation of XOF(Cl)-TPy-BF4/OTf was investigated using proton nuclear magnetic resonance,X-ray photoelectron spectroscopy,infrared,high-resolution transmission electron microscopy,selected area electron diffraction,powder X-ray diffraction,and smallangle X-ray scattering,exhibiting its good crystallinity.Unlike the highly unstable Py2ClBF4/OTf,XOF(Cl)displayed remarkable chemical and thermal stability,even maintaining the periodic framework integrity across various organic solvents.Moreover,the XOF(Cl)can be utilized as a platform to stabilize and immobilize the reactive Pd(0)clusters among the frameworks.The resulting XOF(Cl)-TPy-Pd0 demonstrated excellent catalytic activities in various Pd-catalyzed coupling reactions,including Suzuki,Heck,and Sonogashira couplings,affording high yields even under ambient conditions.Importantly,the synthesis of industrially relevant biphenyl-based liquid crystal molecules using XOF(Cl)-TPy-Pd0 resulted in no detectable palladium residue and the catalyst could be easily recovered via simple filtration and recycled multiple times with consistent catalytic performance.This work not only advances our understanding of chlorine(Ⅰ)chemistry but also establishes a new strategy for the design and development of stable XOFs.The successful demonstration of XOF(Cl)as a robust platform for stabilizing and utilizing reactive species highlights its promising potential for applications in catalysis and beyond. 展开更多
关键词 noncovalent interactions [N…Cl…N]+halogen bond supramolecular assembly anionexchange catalytic coupling
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