The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(...The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.展开更多
Preterm birth(PTB),defined as delivery before 37 weeks of gestation,is the most common adverse pregnancy outcome[1].PTB is a global health concern,with an estimated 13.4 million cases in 2020[1],accounting for more th...Preterm birth(PTB),defined as delivery before 37 weeks of gestation,is the most common adverse pregnancy outcome[1].PTB is a global health concern,with an estimated 13.4 million cases in 2020[1],accounting for more than one in 10 births worldwide.Compared to full-term births,PTBs are associated with a higher risk of short-and long-term complications,including bronchopulmonary dysplasia,necrotizing enterocolitis,visual impairment,and cerebral injuries[2].Despite substantial research efforts to prevent PTB,the global PTB rate has shown little improvement over the past decade[1].Therefore,identifying additional risk factors remains a critical goal in preventing PTB.展开更多
乳腺叶状肿瘤（phyllodes tumor of breast，PTB）是一种少见、类型特殊的肿瘤，其声像图表现缺乏特异性，与其他良恶性肿瘤难以鉴别。PTB首次术式的选择与复发率、病死率关系密切，大多数死亡都是在复发后发生的。因此，术前确诊PTB显...乳腺叶状肿瘤（phyllodes tumor of breast，PTB）是一种少见、类型特殊的肿瘤，其声像图表现缺乏特异性，与其他良恶性肿瘤难以鉴别。PTB首次术式的选择与复发率、病死率关系密切，大多数死亡都是在复发后发生的。因此，术前确诊PTB显得尤为重要。本研究回顾性分析16例经手术病理证实的PTB患者的超声表现，旨在提高超声诊断PTB的可行性及其在指导治疗方面的临床价值。展开更多
基金supported by the Scientific Research Fund of the Education Department of Yunnan Province(Grant Number:2019J0488).
文摘The End-Permian mass extinction(EPME),Earth’s most severe biocrisis,occurred proximal to the Permian-Triassic Boundary(PTB),with marine ecosystems experiencing catastrophic collapse.This study employs stable carbon(δ^(13)C)and oxygen isotopes from marine carbonates in the Haidai Section(Xuanwei,northeastern Yunnan)to decipher paleoenvironmental drivers.The well-preserved stratigraphic sequence encompasses the Upper Permian(Yangxin and Xuanwei Formations)transitioning into the Lower Triassic(Feixianguan and Jialingjiang Formations),providing a continuous marine sedimentary archive.A marked negativeδ^(13)C excursion(-9.66‰V-PDB)occurs at the PTB,initiating from+0.82‰with subsequent gradual recovery.This geochemical signature correlates with:90%reduction in primary productivity Biodiversity collapse exhibiting cluster extinction patterns Prolonged suppression of ecological recovery Concurrently,reconstructed seawater temperatures reveal extreme thermal fluctuations,surging from 23℃to 32℃at the PTB before precipitously declining to 16℃.These perturbations demonstrate coupled biogeochemical dynamics wherein:•Carbon cycle destabilization disrupted nutrient fluxes.•Temperature oscillations exceeded marine taxa thermal tolerances.•Synergistic environmental stresses amplified extinction selectivity.Theδ^(13)C-temperature covariance(r^(2)=0.085)establishes mechanistic linkages between physicochemical perturbations and biotic responses.Our findings demonstrate that the EPME was driven by positive feedback loops in which:Volcanic CO₂emissions triggered carbonate saturation decline Thermal stratification exacerbated anoxia Biogeochemical cycling perturbations suppressed primary producers This integrated geochemical record from the Haidai Section provides critical insights into environment-organism coevolution during Phanerozoic Earth’s most profound mass extinction.
基金supported by the National Natural Science Foundation of China(8200340181972981)+1 种基金the Scientific and Technological Project of Henan Province(222102310150,China)the Open Research Fund of the National Health Commission Key Laboratory of Birth Defects Prevention(NHCKLBDP202504,China).
文摘Preterm birth(PTB),defined as delivery before 37 weeks of gestation,is the most common adverse pregnancy outcome[1].PTB is a global health concern,with an estimated 13.4 million cases in 2020[1],accounting for more than one in 10 births worldwide.Compared to full-term births,PTBs are associated with a higher risk of short-and long-term complications,including bronchopulmonary dysplasia,necrotizing enterocolitis,visual impairment,and cerebral injuries[2].Despite substantial research efforts to prevent PTB,the global PTB rate has shown little improvement over the past decade[1].Therefore,identifying additional risk factors remains a critical goal in preventing PTB.
文摘乳腺叶状肿瘤（phyllodes tumor of breast，PTB）是一种少见、类型特殊的肿瘤，其声像图表现缺乏特异性，与其他良恶性肿瘤难以鉴别。PTB首次术式的选择与复发率、病死率关系密切，大多数死亡都是在复发后发生的。因此，术前确诊PTB显得尤为重要。本研究回顾性分析16例经手术病理证实的PTB患者的超声表现，旨在提高超声诊断PTB的可行性及其在指导治疗方面的临床价值。
