We investigate high time resolution data obtained by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)during the flare event on 2022 April 21 at 01:52 UT.Several subpeaks with durat...We investigate high time resolution data obtained by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)during the flare event on 2022 April 21 at 01:52 UT.Several subpeaks with durations of 4-6 s have been detected in the hard X-ray precursor phase,and the key feature is that they appear in pairs and seem like double-peak struc-tures.These subpeaks are rarely observed in hard X-ray band and confirmed by the microwave obtained by Nobeyama Radio Polarimeters(NoRP)and Radio Solar Telescope Network(RSTN).While an exponential function can describe the continuum component of the time profile from the precursor to part of the impulsive phase.The periods of quasi-periodic pulsations(QPPs)are detected to be about 7.3 and 12.8 s for the precursor and impulsive phase,respectively,with at least 95%confidence level.The paired QPPs are assumed to be double-peak QPPs and then the scenario of current loop coalescence model is found to be in good agreement with our observation.The precursor phase can be interpreted as the oscillating coalescence of two islands,while the impulsive phase can be interpreted as more islands to coalesce one by one to form larger islands.展开更多
美国是全球重要的大豆生产国,中美大豆生产水平差距大,探讨美国大豆品种主要性状的时空演变规律对中国大豆生产具有重要借鉴意义。本研究基于1991—2019年美国213个大豆品种区试站点共计102,244个年点观测数据,综合运用线性回归模型、...美国是全球重要的大豆生产国,中美大豆生产水平差距大,探讨美国大豆品种主要性状的时空演变规律对中国大豆生产具有重要借鉴意义。本研究基于1991—2019年美国213个大豆品种区试站点共计102,244个年点观测数据,综合运用线性回归模型、空间分析和结构方程模型等方法,研究了近30年来美国大豆区试品种(系)农艺和品质性状的时空变化特征。结果表明:(1)1991—2019年美国大豆区试品种(系)数量和大豆单产均呈上升趋势,1991—2003年大豆单产稳定在3000 kg hm^(-2)左右,2004年以来大豆单产以年均46.4 kg hm^(-2)的速度显著增加,近15年大豆平均单产为3525 kg hm^(-2);西部和东部玉米带是美国大豆高产区,2004—2019年美国有22.6%的区试站点大豆单产超过4000 kg hm^(-2),且主要分布于西部玉米带和东部玉米带。(2)近30年美国大豆区试品种(系)的百粒重呈下降趋势,而株高和生育期无显著变化;1991—2003年间百粒重年均下降0.12 g,2004年以来百粒重无明显变化。(3)近30年美国大豆区试品种(系)的蛋白质含量呈下降趋势,平均蛋白质含量从1991—2003年间的41.3%下降到2004—2019年间的40.0%,美国南部地区的蛋白质含量比北部地区高1.4%;油脂呈先下降后增加趋势,平均油脂含量从1991—2003年间的20.3%上升到2004—2019年间的21.3%;2004—2019年美国有59.2%的区试站点大豆油脂含量超过21%。(4)2004—2019年美国大豆区试品种(系)单产水平和油脂含量协同提高,大豆自身农艺性状对单产的制约作用降低。本研究揭示了美国近30年来大豆品种(系)农艺和品质性状的时空变化特征,阐明了不同时期大豆区试品种(系)单产与主要性状之间的关系,可为中国大豆品种高产优质协同发展提供参考。展开更多
As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly wi...As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines.For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time intervals.The central energy of the Gaussian emission line evolves from about 37 to 6 MeV,with a nearly constant ratio(about 10%)between the line width and central energy.Particularly,we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of–1 and–2,respectively.We suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke V line.We find that a standard high latitude emission scenario cannot fully interpret the observation,thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet.In this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and reveal its time evolution(i.e.,Γ~t^(-1))during the prompt emission.Interestingly,we find that the flux of the annihilation line in the co-moving frame keeps constant.These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet.展开更多
The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.T...The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.展开更多
Composite solid electrolytes(CSEs) containing polymer matrices and inorganic fillers hold promise for the next generation of solid-state batteries.However,the role of residual solvents in CSEs remains controversial.Th...Composite solid electrolytes(CSEs) containing polymer matrices and inorganic fillers hold promise for the next generation of solid-state batteries.However,the role of residual solvents in CSEs remains controversial.This study investigated the evolution and function of the residual solvent in a polymer-Li_2B_(12)H_(12) CSE.A partial reaction occurred between Li_2B_(12)H_(12) and solvent N,N-dimethylformamide(DMF),which produced dimethylaminomethanol(DMAM) in the CSE.Density functional theory calculations have revealed that DMA M forms stronger hydrogen bonds with polyvinylidene fluoride chains than DMF,which can have a plasticizing effect on the polymer matrix,leading to lower crystallinity and quicker segment motion.Therefore,this CSE exhibited improved Li-ion conducting properties,enabling the stable cycling of Li‖LiFePO_(4) solid-state batteries.This study provided insights into the role of residual solvents in CSEs.展开更多
The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning cal...The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.展开更多
BACKGROUND Cervical haemorrhage due to spontaneous rupture of a parathyroid adenoma is a rare complication that may cause life-threatening acute airway compromise.CASE SUMMARY A 64-year-old woman was admitted to the h...BACKGROUND Cervical haemorrhage due to spontaneous rupture of a parathyroid adenoma is a rare complication that may cause life-threatening acute airway compromise.CASE SUMMARY A 64-year-old woman was admitted to the hospital 1 day after the onset of right neck enlargement, local tenderness, head-turning difficulty, pharyngeal pain, and mild dyspnoea. Repeat routine blood testing showed a rapid decrease in the haemoglobin concentration, indicating active bleeding. Enhanced computed tomography images showed neck haemorrhage and a ruptured right parathyroid adenoma. The plan was to perform emergency neck exploration, haemorrhage removal, and right inferior parathyroidectomy under general anaesthesia. The patient was administered 50 mg of intravenous propofol, and the glottis was successfully visualised on video laryngoscopy. However, after the administration of a muscle relaxant, the glottis was no longer visible and the patient had a difficult airway that prevented mask ventilation and endotracheal intubation. Fortunately, an experienced anaesthesiologist successfully intubated the patient under video laryngoscopy after an emergency laryngeal mask placement. Postoperative pathology showed a parathyroid adenoma with marked bleeding and cystic changes. The patient recovered well without complications.CONCLUSION Airway management is very important in patients with cervical haemorrhage. After the administration of muscle relaxants, the loss of oropharyngeal support can cause acute airway obstruction.Therefore, muscle relaxants should be administered with caution. Anaesthesiologists should pay careful attention to airway management and have alternative airway devices and tracheotomy equipment available.展开更多
目的探讨心血管风险智能化评估干预方式对社区老年高血压患者的管理效果,为探索高血压管理新模式提供理论依据。方法采用分层抽样于2020年1—6月抽取20家宝安区社区健康服务中心,选取年龄≥60岁的高血压患者1208人,并采用随机数字表法...目的探讨心血管风险智能化评估干预方式对社区老年高血压患者的管理效果,为探索高血压管理新模式提供理论依据。方法采用分层抽样于2020年1—6月抽取20家宝安区社区健康服务中心,选取年龄≥60岁的高血压患者1208人,并采用随机数字表法分为对照组和干预组。对照组给予每个季度常规随访及健康教育,干预组在对照组管理措施的基础上,每次随访给予心血管风险智能化评估和针对性干预措施,进行为期1年随访,采用t检验、χ^(2)检验等评估干预后的管理效果。结果干预组患者在干预后收缩压和舒张压分别为(138.67±19.68)mmHg、(80.95±13.20)mmHg,低于对照组的收缩压(141.04±16.45)mmHg(t=1.998,P=0.045)和舒张压(82.42±11.59)mmHg(t=1.993,P=0.046);干预组干预后的自我护理能力量表(Exercise of Self-care Agency Scale,ESCA)中自我概念、自护责任感、自我护理技能、健康知识水平及总分分别为(20.49±2.41)分、(17.01±3.23)分、(28.91±4.23)分、(50.42±7.09)分、(116.82±9.14)分,均高于对照组得分(18.77±2.41)分(t=7.990,P<0.001)、(15.66±2.06)分(t=5.543,P<0.001)、(27.22±3.14)分(t=4.495,P<0.001)、(47.39±7.50)分(t=5.749,P<0.001)、(109.03±8.81)分(t=10.537,P<0.001);干预组干预后服药遵从行为量表得分为(4.97±0.83)分,高于对照组(4.48±1.03)分(t=5.496,P<0.001);腰围、舒张压等干预后两组差异无统计学意义(P均>0.05)。结论基于心血管风险智能化评估的管理模式,可以有效提高社区老年高血压患者自我护理能力及服药遵从行为,改善患者血压水平,提高患者生活质量。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. U1938102, and 11973092)the National Program on Key Research and Development Project (Grant No. 2016YFA0400802)supported by the Surface Project of Jiangsu Province (Grant No. BK20211402)
文摘We investigate high time resolution data obtained by the Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(GECAM)during the flare event on 2022 April 21 at 01:52 UT.Several subpeaks with durations of 4-6 s have been detected in the hard X-ray precursor phase,and the key feature is that they appear in pairs and seem like double-peak struc-tures.These subpeaks are rarely observed in hard X-ray band and confirmed by the microwave obtained by Nobeyama Radio Polarimeters(NoRP)and Radio Solar Telescope Network(RSTN).While an exponential function can describe the continuum component of the time profile from the precursor to part of the impulsive phase.The periods of quasi-periodic pulsations(QPPs)are detected to be about 7.3 and 12.8 s for the precursor and impulsive phase,respectively,with at least 95%confidence level.The paired QPPs are assumed to be double-peak QPPs and then the scenario of current loop coalescence model is found to be in good agreement with our observation.The precursor phase can be interpreted as the oscillating coalescence of two islands,while the impulsive phase can be interpreted as more islands to coalesce one by one to form larger islands.
文摘美国是全球重要的大豆生产国,中美大豆生产水平差距大,探讨美国大豆品种主要性状的时空演变规律对中国大豆生产具有重要借鉴意义。本研究基于1991—2019年美国213个大豆品种区试站点共计102,244个年点观测数据,综合运用线性回归模型、空间分析和结构方程模型等方法,研究了近30年来美国大豆区试品种(系)农艺和品质性状的时空变化特征。结果表明:(1)1991—2019年美国大豆区试品种(系)数量和大豆单产均呈上升趋势,1991—2003年大豆单产稳定在3000 kg hm^(-2)左右,2004年以来大豆单产以年均46.4 kg hm^(-2)的速度显著增加,近15年大豆平均单产为3525 kg hm^(-2);西部和东部玉米带是美国大豆高产区,2004—2019年美国有22.6%的区试站点大豆单产超过4000 kg hm^(-2),且主要分布于西部玉米带和东部玉米带。(2)近30年美国大豆区试品种(系)的百粒重呈下降趋势,而株高和生育期无显著变化;1991—2003年间百粒重年均下降0.12 g,2004年以来百粒重无明显变化。(3)近30年美国大豆区试品种(系)的蛋白质含量呈下降趋势,平均蛋白质含量从1991—2003年间的41.3%下降到2004—2019年间的40.0%,美国南部地区的蛋白质含量比北部地区高1.4%;油脂呈先下降后增加趋势,平均油脂含量从1991—2003年间的20.3%上升到2004—2019年间的21.3%;2004—2019年美国有59.2%的区试站点大豆油脂含量超过21%。(4)2004—2019年美国大豆区试品种(系)单产水平和油脂含量协同提高,大豆自身农艺性状对单产的制约作用降低。本研究揭示了美国近30年来大豆品种(系)农艺和品质性状的时空变化特征,阐明了不同时期大豆区试品种(系)单产与主要性状之间的关系,可为中国大豆品种高产优质协同发展提供参考。
基金supported by the National Key R&D Program of China(Grant Nos.2021YFA0718500,and 2023YFE0101200)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA15360102,XDA15360300,and XDA15052700)+3 种基金the National Natural Science Foundation of China(Grant Nos.12273042,61234003,61434004,61504141,11673062,12393813,2333007,12027803,and 12303045)the CAS Interdisciplinary Project(Grant No.KJZD-EW-L11-04)supported by the Strategic Priority Research Program on Space Science(Grant No.XDA15360000)of the Chinese Academy of Sciencessupported by the Yunnan Revitalization Talent Support Program(Yun Ling Scholar Award)。
文摘As the brightest gamma-ray burst ever observed,GRB 221009A provided a precious opportunity to explore spectral line features.In this article,we performed a comprehensive spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption lines.For the first time we investigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time intervals.The central energy of the Gaussian emission line evolves from about 37 to 6 MeV,with a nearly constant ratio(about 10%)between the line width and central energy.Particularly,we find that both the central energy and the energy flux of the emission line evolve with time as a power law decay with power law index of–1 and–2,respectively.We suggest that the observed emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke V line.We find that a standard high latitude emission scenario cannot fully interpret the observation,thus we propose that the emission line comes from some dense clumps with electron positron pairs traveling together with the jet.In this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and reveal its time evolution(i.e.,Γ~t^(-1))during the prompt emission.Interestingly,we find that the flux of the annihilation line in the co-moving frame keeps constant.These discoveries of the spectral line features shed new and important lights on the physics of GRB and relativistic jet.
基金grateful for the financial support from the National Natural Science Foundation of China(51904156,51971163 and 51705082)the Open Fund of Jiangsu Wind Power Engineering Technology Center(ZK22-03-02)the Ten thousand talents project of Zhejiang Province(2019R52056).
文摘The grain boundary(GB)damage of long-term crept HR3C(25Cr–20Ni–Nb–N)austenitic steel with solid solution state was investigated by nanoindentation test accompanied with in-situ electron back-scattered diffraction.The corresponding microstructure was characterized by scanning electron microscopy and transmission electron microscopy.Results show that the increase in nanoindentation hardness at the GBs and triple grain junctions may be related to the dislocation accumulation and carbide growth during the creep.Coarsened M23C6 and dislocations piling-up at the GB accelerate the nucleation and coalescence of creep cavity along the GB.The nanoindentation hardness in grains varies with orientation of the stress axis.The orientation difference of neighbor grains may induce local high geometrically necessary dislocation densities and strain gradients near the GB,consequently causing stress concentration and subsequent crack growth at specific GBs.
基金financially supported by the National Natural Science Foundation of China (Nos.51971146,51971147,52171218 and 52271222)Shanghai Municipal Science and Technology Commission (No.21010503100)+3 种基金the Major Program for the Scientific Research Innovation Plan of Shanghai Education Commission (No.2019-01-07-00-07-E00015)Shanghai Outstanding Academic Leaders Plan,Guangxi Key Laboratory of Information Materials (Guilin University of Electronic Technology,201017-K)Shanghai Rising-Star Program (No.20QA1407100)General Program of Natural Science Foundation of Shanghai (No.20ZR1438400)。
文摘Composite solid electrolytes(CSEs) containing polymer matrices and inorganic fillers hold promise for the next generation of solid-state batteries.However,the role of residual solvents in CSEs remains controversial.This study investigated the evolution and function of the residual solvent in a polymer-Li_2B_(12)H_(12) CSE.A partial reaction occurred between Li_2B_(12)H_(12) and solvent N,N-dimethylformamide(DMF),which produced dimethylaminomethanol(DMAM) in the CSE.Density functional theory calculations have revealed that DMA M forms stronger hydrogen bonds with polyvinylidene fluoride chains than DMF,which can have a plasticizing effect on the polymer matrix,leading to lower crystallinity and quicker segment motion.Therefore,this CSE exhibited improved Li-ion conducting properties,enabling the stable cycling of Li‖LiFePO_(4) solid-state batteries.This study provided insights into the role of residual solvents in CSEs.
文摘The kinetics of the thermal decomposition for a naturally ageing ammonium perchlorate(AP) and hydroxyl-terminated-polybutadiene(HTPB) base bleed composite propellant were investigated using a differential scanning calorimetry(DSC). The naturally ageing AP/HTPB base bleed propellant samples have been stored in a sealed plastic bag at room temperature(5-25 ℃) for more than 20 years. The experimental DSC results were obtained by placing samples(each about 1.5 mg) in a sealed pan under non-isothermal condition under different heating rates, 5.0, 10.0, 15.0, 20.0 and 30.0 ℃·min^(-1). The activation energy and pre-exponential factor were estimated based on the relationship between the exothermic peak temperature and the heating rate by Ozawa and Kissinger methods, respectively. The decomposition kinetic parameters is lower the values under laboratorial aging condition.
基金Supported by Key Clinical Projects of Peking University Third Hospital,No. BYSYZD2021013Beijing Haidian District Innovation and transformation project,No. HDCXZHZB2021202。
文摘BACKGROUND Cervical haemorrhage due to spontaneous rupture of a parathyroid adenoma is a rare complication that may cause life-threatening acute airway compromise.CASE SUMMARY A 64-year-old woman was admitted to the hospital 1 day after the onset of right neck enlargement, local tenderness, head-turning difficulty, pharyngeal pain, and mild dyspnoea. Repeat routine blood testing showed a rapid decrease in the haemoglobin concentration, indicating active bleeding. Enhanced computed tomography images showed neck haemorrhage and a ruptured right parathyroid adenoma. The plan was to perform emergency neck exploration, haemorrhage removal, and right inferior parathyroidectomy under general anaesthesia. The patient was administered 50 mg of intravenous propofol, and the glottis was successfully visualised on video laryngoscopy. However, after the administration of a muscle relaxant, the glottis was no longer visible and the patient had a difficult airway that prevented mask ventilation and endotracheal intubation. Fortunately, an experienced anaesthesiologist successfully intubated the patient under video laryngoscopy after an emergency laryngeal mask placement. Postoperative pathology showed a parathyroid adenoma with marked bleeding and cystic changes. The patient recovered well without complications.CONCLUSION Airway management is very important in patients with cervical haemorrhage. After the administration of muscle relaxants, the loss of oropharyngeal support can cause acute airway obstruction.Therefore, muscle relaxants should be administered with caution. Anaesthesiologists should pay careful attention to airway management and have alternative airway devices and tracheotomy equipment available.
文摘目的探讨心血管风险智能化评估干预方式对社区老年高血压患者的管理效果,为探索高血压管理新模式提供理论依据。方法采用分层抽样于2020年1—6月抽取20家宝安区社区健康服务中心,选取年龄≥60岁的高血压患者1208人,并采用随机数字表法分为对照组和干预组。对照组给予每个季度常规随访及健康教育,干预组在对照组管理措施的基础上,每次随访给予心血管风险智能化评估和针对性干预措施,进行为期1年随访,采用t检验、χ^(2)检验等评估干预后的管理效果。结果干预组患者在干预后收缩压和舒张压分别为(138.67±19.68)mmHg、(80.95±13.20)mmHg,低于对照组的收缩压(141.04±16.45)mmHg(t=1.998,P=0.045)和舒张压(82.42±11.59)mmHg(t=1.993,P=0.046);干预组干预后的自我护理能力量表(Exercise of Self-care Agency Scale,ESCA)中自我概念、自护责任感、自我护理技能、健康知识水平及总分分别为(20.49±2.41)分、(17.01±3.23)分、(28.91±4.23)分、(50.42±7.09)分、(116.82±9.14)分,均高于对照组得分(18.77±2.41)分(t=7.990,P<0.001)、(15.66±2.06)分(t=5.543,P<0.001)、(27.22±3.14)分(t=4.495,P<0.001)、(47.39±7.50)分(t=5.749,P<0.001)、(109.03±8.81)分(t=10.537,P<0.001);干预组干预后服药遵从行为量表得分为(4.97±0.83)分,高于对照组(4.48±1.03)分(t=5.496,P<0.001);腰围、舒张压等干预后两组差异无统计学意义(P均>0.05)。结论基于心血管风险智能化评估的管理模式,可以有效提高社区老年高血压患者自我护理能力及服药遵从行为,改善患者血压水平,提高患者生活质量。
