To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 1...To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 100%,as well as on undisturbed and reconstituted non-plastic sandy soils retrieved from earth structures with a history of earthquake-induced damage.The specimens on sand-silt mixtures were produced under an initial degree of compaction of 95%.In these tests,liquefaction histories were applied three times to a single specimen under the same cyclic stress ratio after the respective consolidation stages with the measurements of the shear wave velocities.The following conclusions can be obtained from the test results:(1)The liquefaction resistance obtained in the firstto third cyclicloading stages decreased initially with increasing finescontent up to about 45%,while it increased afterward.Therefore,the susceptibility of sands containing a relatively large amount of non-plastic silt to reliquefaction may be more significantthan that of clean sands;(2)The liquefaction resistance and the shear wave velocity decreased significantlyduring the second cyclic-loading stage and after the second consolidation,respectively,despite an increase in the specimen density caused by the first liquefaction history,while they increased in the third stage.The possible reason for this change would be the disturbance of soil structures due to liquefaction,which may be partially evaluated by the volumetric strain during the respective consolidation stages,and the stress-induced anisotropy formed in the previous liquefaction stage;and(3)The liquefaction resistance and the shear wave velocity of the undisturbed specimens,which were measured in the firstto third stages,were larger than those of the reconstituted ones due to the aging effects,respectively.That is,the aging effects may not necessarily be eliminated by the subsequent liquefaction history and may remain partially in some cases.展开更多
针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案...针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案并优选“设置分流锥”方案。基于颗粒预热数学模型与气固耦合模型,采用ANSYS CFX对60°、90°、120°顶角分流锥的流道工况进行数值模拟,对比分析流速、湍流涡耗散、湍流动能等流场特征,并通过Q-criterion准则解析旋涡结构演化规律。结果表明:上部锥形顶角60°分流锥方案最优,可显著提升流动与预热性能,降低功能退化量;有限单元法验证显示其结构可靠性满足设计要求。可见,提出的方案可谓探索预热压力罐优化设计提供新思路。展开更多
背景:运动干预作为经济有效的非物理疗法,可有效上调脑源性神经营养因子表达进而防治帕金森病发生发展,但目前关于靶向脑源性神经营养因子的运动治疗策略在延缓帕金森病发生发展的潜在作用机制尚不明晰。目的:以脑源性神经营养因子和帕...背景:运动干预作为经济有效的非物理疗法,可有效上调脑源性神经营养因子表达进而防治帕金森病发生发展,但目前关于靶向脑源性神经营养因子的运动治疗策略在延缓帕金森病发生发展的潜在作用机制尚不明晰。目的:以脑源性神经营养因子和帕金森病的关系为切入点,分析帕金森病病理状态下运动对脑源性神经营养因子表达的特异性调控作用及机制,梳理脑源性神经营养因子介导下不同运动方式对帕金森病的改善效果,并阐明靶向脑源性神经营养因子的运动治疗策略在防治帕金森病的潜在作用机制,旨在为运动防治帕金森病提供新的理论依据。方法:以“帕金森病,脑源性神经营养因子,神经保护,多巴胺,神经元异常凋亡,神经炎症反应,突触可塑性,运动”等为中文检索词;以“Parkinson’s disease,BDNF,Neuroprotection,neuroinflammation,synaptic plasticity”等为英文检索词,分别检索中国知网、万方数据库、PubMed和Web of Science数据库,搜寻各数据库建库至2024年2月发表的所有研究文献,根据纳排标准共获得核心相关文献98篇。结果与结论:①在帕金森病理背景下,运动可通过促进肌因子鸢尾素大量分泌,并降低色氨酸-犬尿氨酸代谢途径紊乱特异性调控脑源性神经营养因子表达。②有氧运动,尤其是特殊有氧运动(动物:旋转杆步行/人类:北欧健走)以及多模式运动可显著上调脑源性神经营养因子表达,进而改善帕金森病的运动症状,此外脑源性神经营养因子还介导身心运动(太极拳)对帕金森病患者认知障碍和睡眠障碍等非运动症状的有效调节。③运动诱导的高表达脑源性神经营养因子可能通过上调抗炎因子白细胞介素10、神经生长因子β和转化生长因子β表达,下调促炎因子肿瘤坏死因子α及白细胞介素1β表达,并抑制核转录因子κB信号通路表达降低小胶质细胞活性减轻神经炎症反应;增加酪氨酸羟化酶活性以促进多巴胺合成释放,并通过下调基质金属蛋白酶3及糖原合成酶激酶3β表达抑制α-突触核蛋白在丝氨酸129位点的磷酸化修饰,以防止神经异常凋亡;诱导突触效能的长时程增强发生,促进突触后致密区蛋白95及突触素大量表达以改善突触可塑性,发挥神经保护作。④鉴于脑源性神经营养因子在帕金森病发病进程及治疗中发挥重要作用,靶向脑源性神经营养因子的运动治疗策略将有助于推动帕金森病疾病“运动+药物”精准医疗的发展。但由于目前研究采用的运动处方较为单一,且研究焦点主要围绕运动症状而缺乏对非运动症状的考察,因此亟待学者采用更加统一和系统的运动处方,围绕非有氧运动类型对同一批帕金森病患者进行长期纵向跟踪研究,以此完善帕金森病运动防治领域研究的不足。展开更多
基金supported by JSPS KAKENHI(Grant Nos.JP22K04305 and JP19K15083).
文摘To investigate the influencesof non-plastic silt and soil aging on the re-liquefaction resistance of sands,a series of undrained triaxial tests was performed on sand-silt mixtures with finescontent ranging from 0%to 100%,as well as on undisturbed and reconstituted non-plastic sandy soils retrieved from earth structures with a history of earthquake-induced damage.The specimens on sand-silt mixtures were produced under an initial degree of compaction of 95%.In these tests,liquefaction histories were applied three times to a single specimen under the same cyclic stress ratio after the respective consolidation stages with the measurements of the shear wave velocities.The following conclusions can be obtained from the test results:(1)The liquefaction resistance obtained in the firstto third cyclicloading stages decreased initially with increasing finescontent up to about 45%,while it increased afterward.Therefore,the susceptibility of sands containing a relatively large amount of non-plastic silt to reliquefaction may be more significantthan that of clean sands;(2)The liquefaction resistance and the shear wave velocity decreased significantlyduring the second cyclic-loading stage and after the second consolidation,respectively,despite an increase in the specimen density caused by the first liquefaction history,while they increased in the third stage.The possible reason for this change would be the disturbance of soil structures due to liquefaction,which may be partially evaluated by the volumetric strain during the respective consolidation stages,and the stress-induced anisotropy formed in the previous liquefaction stage;and(3)The liquefaction resistance and the shear wave velocity of the undisturbed specimens,which were measured in the firstto third stages,were larger than those of the reconstituted ones due to the aging effects,respectively.That is,the aging effects may not necessarily be eliminated by the subsequent liquefaction history and may remain partially in some cases.
文摘针对预热压力容器罐出料口堵塞、颗粒预热不足等性能缺陷,提出融合TRIZ(theory of inventive problem solving)创新理论与数值模拟的系统解决方案。通过构建技术系统功能模型、专创融合解题流程及性能提升框架,结合ARIZ算法生成多方案并优选“设置分流锥”方案。基于颗粒预热数学模型与气固耦合模型,采用ANSYS CFX对60°、90°、120°顶角分流锥的流道工况进行数值模拟,对比分析流速、湍流涡耗散、湍流动能等流场特征,并通过Q-criterion准则解析旋涡结构演化规律。结果表明:上部锥形顶角60°分流锥方案最优,可显著提升流动与预热性能,降低功能退化量;有限单元法验证显示其结构可靠性满足设计要求。可见,提出的方案可谓探索预热压力罐优化设计提供新思路。
文摘背景:运动干预作为经济有效的非物理疗法,可有效上调脑源性神经营养因子表达进而防治帕金森病发生发展,但目前关于靶向脑源性神经营养因子的运动治疗策略在延缓帕金森病发生发展的潜在作用机制尚不明晰。目的:以脑源性神经营养因子和帕金森病的关系为切入点,分析帕金森病病理状态下运动对脑源性神经营养因子表达的特异性调控作用及机制,梳理脑源性神经营养因子介导下不同运动方式对帕金森病的改善效果,并阐明靶向脑源性神经营养因子的运动治疗策略在防治帕金森病的潜在作用机制,旨在为运动防治帕金森病提供新的理论依据。方法:以“帕金森病,脑源性神经营养因子,神经保护,多巴胺,神经元异常凋亡,神经炎症反应,突触可塑性,运动”等为中文检索词;以“Parkinson’s disease,BDNF,Neuroprotection,neuroinflammation,synaptic plasticity”等为英文检索词,分别检索中国知网、万方数据库、PubMed和Web of Science数据库,搜寻各数据库建库至2024年2月发表的所有研究文献,根据纳排标准共获得核心相关文献98篇。结果与结论:①在帕金森病理背景下,运动可通过促进肌因子鸢尾素大量分泌,并降低色氨酸-犬尿氨酸代谢途径紊乱特异性调控脑源性神经营养因子表达。②有氧运动,尤其是特殊有氧运动(动物:旋转杆步行/人类:北欧健走)以及多模式运动可显著上调脑源性神经营养因子表达,进而改善帕金森病的运动症状,此外脑源性神经营养因子还介导身心运动(太极拳)对帕金森病患者认知障碍和睡眠障碍等非运动症状的有效调节。③运动诱导的高表达脑源性神经营养因子可能通过上调抗炎因子白细胞介素10、神经生长因子β和转化生长因子β表达,下调促炎因子肿瘤坏死因子α及白细胞介素1β表达,并抑制核转录因子κB信号通路表达降低小胶质细胞活性减轻神经炎症反应;增加酪氨酸羟化酶活性以促进多巴胺合成释放,并通过下调基质金属蛋白酶3及糖原合成酶激酶3β表达抑制α-突触核蛋白在丝氨酸129位点的磷酸化修饰,以防止神经异常凋亡;诱导突触效能的长时程增强发生,促进突触后致密区蛋白95及突触素大量表达以改善突触可塑性,发挥神经保护作。④鉴于脑源性神经营养因子在帕金森病发病进程及治疗中发挥重要作用,靶向脑源性神经营养因子的运动治疗策略将有助于推动帕金森病疾病“运动+药物”精准医疗的发展。但由于目前研究采用的运动处方较为单一,且研究焦点主要围绕运动症状而缺乏对非运动症状的考察,因此亟待学者采用更加统一和系统的运动处方,围绕非有氧运动类型对同一批帕金森病患者进行长期纵向跟踪研究,以此完善帕金森病运动防治领域研究的不足。
