Spontaneous preterm birth (SPTB) is characterized by the delivery of a baby before 37 completed weeks of gestation, and this condition is associated with significant health challenges for the newborn. Emerging evidenc...Spontaneous preterm birth (SPTB) is characterized by the delivery of a baby before 37 completed weeks of gestation, and this condition is associated with significant health challenges for the newborn. Emerging evidence highlights the importance of biomarkers for understanding the mechanisms underlying SPTB. One such biomarker, 8-OH-2dG, plays a critical role in evaluating oxidative stress and its impact on pregnancy outcomes. It has been demonstrated that 8-OH-2dG is a product of oxidative DNA damage and is widely recognized as a key indicator of cellular oxidative stress. Elevated reactive oxygen species in SPTB result in higher levels of the DNA degradation product 8-OH-2dG in amniotic fluid, causing damage to maternal and fetal tissues that could lead to premature rupture of fetal membranes. Therefore, evaluating the role of 8-OH-2dG in SPTB is of great interest. This review provides an overview of the current knowledge on 8-OH-2dG as a biomarker for SPTB and aims to elucidate its mechanism in this condition.展开更多
目的分析1995-2023年分娩心理创伤(psychological birth trauma,PBT)研究主题的热点变迁及其发展趋势,为今后开展精准筛查、预防及干预PBT研究提供参考依据。方法检索中国知网、万方数据库、Web of science和Scopus数据库,获取PBT的相...目的分析1995-2023年分娩心理创伤(psychological birth trauma,PBT)研究主题的热点变迁及其发展趋势,为今后开展精准筛查、预防及干预PBT研究提供参考依据。方法检索中国知网、万方数据库、Web of science和Scopus数据库,获取PBT的相关文献,经过人工筛查最终纳入565篇文献。运用CiteSpace对该研究的发文量、关键词进行可视化分析。结果PBT研究始于1995年,预测高峰时期为2026年。高中心性的关键词为创伤后应激障碍、创伤后应激、母婴互动、产后抑郁等。研究前沿多聚焦于分娩方式、分娩满意度等方面。结论目前PBT研究处于发展期,并位于高峰增长的前夕。建议深入研究并探索PBT的最佳干预措施,提升母婴的身心健康水平,并为有效预防及治疗产后精神心理障碍提供最佳证据。展开更多
With a focus on the intake tower of the Yanshan Reservoir, this paper discusses the method of modeling in the 3D CAD software SolidWorks and the interface processing between SolidWorks and the ANSYS code, which decrea...With a focus on the intake tower of the Yanshan Reservoir, this paper discusses the method of modeling in the 3D CAD software SolidWorks and the interface processing between SolidWorks and the ANSYS code, which decreases the difficulty in modeling complicated models in ANSYS. In view of the function of the birth-death element and secondary development with APDL （ANSYS parametric design language）, a simulation analysis of the temperature field and thermal stress during the construction period of the intake tower was conveniently conducted. The results show that the temperature rise is about 29.934 ℃ over 3 or 4 days. The temperature differences between any two points are less than 24 ℃. The thermal stress increases with the temperature difference and reaches its maximum of 1.68 MPa at the interface between two concrete layers.展开更多
Residual stresses can have a strong effect on the usability of machined parts,and the X-ray diffraction(XRD)measuring equipment,which is commonly used to measure residual stresses,is very expensive.This paper presents...Residual stresses can have a strong effect on the usability of machined parts,and the X-ray diffraction(XRD)measuring equipment,which is commonly used to measure residual stresses,is very expensive.This paper presents a method of measuring the residual stresses induced by boring in the internal surface of a tube with much cheaper equipment.The method,called the strain-based method is mainly based on the strains measured on the external surface of the tube.It is proposed on the basis of the very long tube assumption.The finite element method(FEM)analysis is thus used to validate the length of the tube.Guided by the FEM results,an appropriate length of the tube is chosen,and the residual stresses are obtained from both the strain-based method and the XRD method.Stress profiles obtained from both two methods are compared.The comparison result indicates that the profiles of the two methods agree well with each other.Therefore,it can be concluded that the accuracy of the strain-based method is high enough,and it can be applied to residual stress measurement in practice.展开更多
The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, th...The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, the influences of spinning parameters on the distribution of the residual stress were investigated in detail, and the formation mechanism of residual stress during tube spinning was discussed. Based on the calculation of the residual stress, the reasons for annealing cracks on the spun tube during interpass heat treatment were explored. The simulation results and the characteristics of annealing cracks show that the circumferential residual tensile stress is a main factor to cause the annealing cracks.展开更多
文摘Spontaneous preterm birth (SPTB) is characterized by the delivery of a baby before 37 completed weeks of gestation, and this condition is associated with significant health challenges for the newborn. Emerging evidence highlights the importance of biomarkers for understanding the mechanisms underlying SPTB. One such biomarker, 8-OH-2dG, plays a critical role in evaluating oxidative stress and its impact on pregnancy outcomes. It has been demonstrated that 8-OH-2dG is a product of oxidative DNA damage and is widely recognized as a key indicator of cellular oxidative stress. Elevated reactive oxygen species in SPTB result in higher levels of the DNA degradation product 8-OH-2dG in amniotic fluid, causing damage to maternal and fetal tissues that could lead to premature rupture of fetal membranes. Therefore, evaluating the role of 8-OH-2dG in SPTB is of great interest. This review provides an overview of the current knowledge on 8-OH-2dG as a biomarker for SPTB and aims to elucidate its mechanism in this condition.
文摘目的分析1995-2023年分娩心理创伤(psychological birth trauma,PBT)研究主题的热点变迁及其发展趋势,为今后开展精准筛查、预防及干预PBT研究提供参考依据。方法检索中国知网、万方数据库、Web of science和Scopus数据库,获取PBT的相关文献,经过人工筛查最终纳入565篇文献。运用CiteSpace对该研究的发文量、关键词进行可视化分析。结果PBT研究始于1995年,预测高峰时期为2026年。高中心性的关键词为创伤后应激障碍、创伤后应激、母婴互动、产后抑郁等。研究前沿多聚焦于分娩方式、分娩满意度等方面。结论目前PBT研究处于发展期,并位于高峰增长的前夕。建议深入研究并探索PBT的最佳干预措施,提升母婴的身心健康水平,并为有效预防及治疗产后精神心理障碍提供最佳证据。
基金supported by the Natural Science Foundation of Henan Province (Grant No. 511050100)
文摘With a focus on the intake tower of the Yanshan Reservoir, this paper discusses the method of modeling in the 3D CAD software SolidWorks and the interface processing between SolidWorks and the ANSYS code, which decreases the difficulty in modeling complicated models in ANSYS. In view of the function of the birth-death element and secondary development with APDL （ANSYS parametric design language）, a simulation analysis of the temperature field and thermal stress during the construction period of the intake tower was conveniently conducted. The results show that the temperature rise is about 29.934 ℃ over 3 or 4 days. The temperature differences between any two points are less than 24 ℃. The thermal stress increases with the temperature difference and reaches its maximum of 1.68 MPa at the interface between two concrete layers.
基金Supported by the National Defense Program of China(C152012C002)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20123218120025)
文摘Residual stresses can have a strong effect on the usability of machined parts,and the X-ray diffraction(XRD)measuring equipment,which is commonly used to measure residual stresses,is very expensive.This paper presents a method of measuring the residual stresses induced by boring in the internal surface of a tube with much cheaper equipment.The method,called the strain-based method is mainly based on the strains measured on the external surface of the tube.It is proposed on the basis of the very long tube assumption.The finite element method(FEM)analysis is thus used to validate the length of the tube.Guided by the FEM results,an appropriate length of the tube is chosen,and the residual stresses are obtained from both the strain-based method and the XRD method.Stress profiles obtained from both two methods are compared.The comparison result indicates that the profiles of the two methods agree well with each other.Therefore,it can be concluded that the accuracy of the strain-based method is high enough,and it can be applied to residual stress measurement in practice.
基金the National Natural Science Foundation of China(No.59995444).
文摘The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, the influences of spinning parameters on the distribution of the residual stress were investigated in detail, and the formation mechanism of residual stress during tube spinning was discussed. Based on the calculation of the residual stress, the reasons for annealing cracks on the spun tube during interpass heat treatment were explored. The simulation results and the characteristics of annealing cracks show that the circumferential residual tensile stress is a main factor to cause the annealing cracks.
