Factors driving surface deformations in plain area of eastern Zhengzhou City,China

With the rapid socio-economic development and urban expansion,land subsidence has emerged as a major environmental issue,impeding the high-quality development of the plain area in eastern Zhengzhou City,Henan Province,China.However,effective prevention and control of land subsidence in this region have been challenging due to the lack of comprehensive surface deformations monitoring and the quantitative analysis of the factors driving these deformations.In order to accurately identify the dominant factor driving surface deformations in the study area,this study utilized the Persistent Scattered Interferometric Synthetic Aperture Radar(PS-InSAR)technique to acquire the spatio-temporal distribution of surface deformations from January 2018 to March 2020.The acquired data was verified using leveling data.Subsequently,GIS spatial analysis was employed to investigate the responses of surface deformations to the driving factors.The findings are as follows:Finally,the geographical detector model was utilized to quantify the contributions of the driving factors and reveal the mechanisms of their interactions.The findings are as follows:(1)Surface deformations in the study area are dominated by land subsidence,concentrated mainly in Zhongmu County,with a deformation rate of−12.5–−37.1 mm/a.In contrast,areas experiencing surface uplift are primarily located downtown,with deformation rates ranging from 0 mm to 8 mm;(2)Groundwater level,lithology,and urban construction exhibit strong spatial correlations with cumulative deformation amplitude;(3)Groundwater level of the second aquifer group is the primary driver of spatially stratified heterogeneity in surface deformations,with a contributive degree of 0.5328.The contributive degrees of driving factors are significantly enhanced through interactions.Groundwater level and the cohesive soil thickness in the second aquifer group show the strongest interactions in the study area.Their total contributive degree increases to 0.5722 after interactions,establishing them as the primary factors influencing surface deformation patterns in the study area.The results of this study can provide a theoretical basis and scientific support for precise prevention and control measures against land subsidence in the study area,as well as contributing to research on the underlying mechanisms.

冠状动脉微循环阻力指数与传统心血管危险因素、Hcy及LP-PLA2的相关性研究

目的探讨冠状动脉(冠脉)微循环障碍与LP-PLA2、Hcy的相关性,以及其发生、发展的相关危险因素。方法 63例冠脉造影显示临界病变(狭窄40%～70%,且测量冠脉血流储备分数(FFR)>0.8),冠脉造影术后测量前降支微循环阻力指数(IMR)值,以IMR中位数为界分为IMR正常组(<21.3 u)和IMR升高组(≥21.3 u)。分别记录和测定两组一般资料、相关生化指标、心血管疾病危险因素和血浆脂蛋白相关磷脂酶A2(LP-PLA2)及同型半胱氨酸(Hcy)值,分析各指标与IMR的关系。结果 63例患者完成IMR测量,IMR范围:6.5～42.3 u,中位数:21.3 u,与正常组比较,IMR升高组HDL-C和CFR更低,而Hcy和年龄较高(P <0.05);IMR值与Hcy、年龄及LDL-C(r=0.263)呈正相关(P <0.05),与CFR、HDL-C呈负相关(P <0.05),与LPLPA2水平无相关性(P>0.05);多因素logistic回归分析显示,年龄、Hcy是IMR升高的危险因素(P <0.05),HDL-C、CFR是IMR升高的保护因素(P <0.05)。结论 (1) FFR>0.8的冠脉临界病变中,CFR可作为评估冠脉微循环的指标;(2)年龄和Hcy是冠脉微循环障碍的危险因素,CFR和HDL-C是冠脉微循环的保护因素;(3)年龄的增长、HDL-C水平的降低和Hcy可能参与冠脉微循环障碍的病理过程,导致IMR值升高。

Formation mechanism and growth kinetics of TiAl_(3) phase in cold-rolled Ti/Al laminated composites during annealing

Cold-rolled Ti/Al laminated composites were annealed at 525−625℃for 0−128 h,and the interfacial microstructure evolution was investigated.The results indicate that only the TiAl_(3) phase was formed at the Ti/Al interface;most of TiAl_(3) grains were fine equiaxed with average sizes ranging from hundreds of nanometers to several microns and the TiAl_(3) grain size increased with increasing annealing time and/or temperature,but the effect of annealing temperature on the TiAl_(3) grain size was far greater than that of annealing time.The growth of the TiAl_(3) phase consisted of two stages.The initial stage was governed by chemical reaction with a reaction activation energy of 195.75 kJ/mol,and the reaction rate constant of the TiAl_(3) phase was larger as the Ti/Al interface was bonded with fresh surfaces.At the second stage,the growth was governed by diffusion,the diffusion activation energy was 33.69 kJ/mol,and the diffusion growth rate constant of the TiAl_(3) phase was mainly determined by the grain boundary diffusion owing to the smaller TiAl_(3) grain size.

Cu-Al interfacial compounds and formation mechanism of copper cladding aluminum composites

Copper cladding aluminum(CCA)rods with the section dimensions of12mm in diameter and2mm in sheath thickness were fabricated by vertical core-filling continuous casting(VCFC)technology.The kinds and morphology of interfacial intermetallic compounds(IMCs)were investigated by SEM,XRD and TEM.The results showed that the interfacial structure of Cu/Al was mainly composed of layeredγ1(Cu9Al4),cellularθ(CuAl2),andα(Al)+θ(CuAl2)phases.Moreover,residual acicularε2(Cu3Al2+x)phase was observed at the Cu/Al interface.By comparing the driving force of formation forε2(Cu3Al2+x)andγ1(Cu9Al4)phases,the conclusion was drawn that theε2(Cu3Al2+x)formed firstly at the Cu/Al interface.In addition,the interfacial formation mechanism of copper cladding aluminum composites was revealed completely.

Dual-wavelength rectangular pulse erbium-doped fiber laser based on topological insulator saturable absorber

We reported on the generation of the dual-wavelength rectangular pulse in an erbium-doped fiber laser(EDFL)with a topological insulator saturable absorber.The rectangular pulse could be stably initiated with pulse width from 13.62 to 25.16 ns and fundamental repetition rate of 3.54 MHz by properly adjusting the pump power and the polarization state.In addition,we verified that the pulse shape of the dual-wavelength rectangular pulse can be affected by the total net cavity dispersion in the fiber laser.Furthermore,by properly rotating the polarization controllers,the harmonic mode-locking operation of the dual-wavelength rectangular pulse was also obtained.The dual-wavelength rectangular pulse EDFL would benefit some potential applications,such as spectroscopy,biomedicine,and sensing research.