Effect of endoscopic full-thickness resection assisted by distal serosal turnover with floss traction for gastric submucosal masses

BACKGROUND Complex and high-risk surgical complications pose pressing challenges in the clinical implementation and advancement of endoscopic full-thickness resection(EFTR).Successful perforation repair under endoscopy,thereby avoiding surgical intervention and postoperative complications such as peritonitis,are pivotal for effective EFTR.AIM To investigate the effectiveness and safety of EFTR assisted by distal serosal inversion under floss traction in gastric submucosal tumors.METHODS A retrospective analysis of patients with gastric and duodenal submucosal tumors treated with EFTR assisted by the distal serosa inversion under dental floss traction from January 2023 to January 2024 was conducted.The total operation time,tumor dissection time,wound closure time,intraoperative bleeding volume,length of hospital stay and incidence of complications were analyzed.RESULTS There were 93 patients,aged 55.1±12.1 years.Complete tumor resection was achieved in all cases,resulting in a 100% success rate.The average total operation time was 67.4±27.0 min,with tumor dissection taking 43.6±20.4 min.Wound closure times varied,with gastric body closure time of 24.5±14.1 min and gastric fundus closure time of 16.6±8.7 min,showing a significant difference(P<0.05).Intraoperative blood loss was 2.3±4.0 mL,and average length of hospital stay was 5.7±1.9 d.There was no secondary perforation after suturing in all cases.The incidence of delayed bleeding was 2.2%,and the incidence of abdominal infection was 3.2%.No patient required other surgical intervention during and after the operation.CONCLUSION Distal serosal inversion under dental-floss-assisted EFTR significantly reduced wound closure time and intraoperative blood loss,making it a viable approach for gastric submucosal tumors.

Microstructure and mechanical properties of squeeze-cast Al−5.0Mg−3.0Zn−1.0Cu alloys in solution-treated and aged conditions

The microstructure and mechanical properties at different depths of squeeze-cast,solution-treated and aged Al−5.0Mg−3.0Zn−1.0Cu alloy were investigated.For squeeze-cast alloy,from casting surface to interior,the grain size ofα(Al)matrix and width of T-Mg32(AlZnCu)49 phase increase significantly,while the volume fraction of T phase decreases.The related mechanical properties including ultimate tensile strength(UTS)and elongation decrease from 243.7 MPa and 2.3%to 217.9 MPa and 1.4%,respectively.After solution treatment at 470℃ for 36 h,T phase is dissolved into matrix,and the grain size increases so that the UTS and elongation from surface to interior are respectively reduced from 387.8 MPa and 18.6%to 348.9 MPa and 13.9%.After further peak-aging at 120℃ for 24 h,numerous G.P.II zone andη′phase precipitate in matrix.Consequently,UTS values of the surface and interior increase to 449.5 and 421.4 MPa,while elongation values decrease to 12.5%and 8.1%,respectively.

Conversion relationship of rainfall-soil moisture-groundwater in Quaternary thick cohesive soil in Jianghan Plain,Hubei Province,China

The scientific field test site of rainfall-soil moisture-groundwater conversion in Dabie Mountain Area–Jianghan Plain is located in the northern region of the Jianghan Plain,the transition zone between the Dabie Mountain Area and Jianghan Plain.It’s a great field test site to study the material and energy exchange among rainfall,soil moisture,and groundwater of the Earth’s critical zone in subtropical monsoon climate plain areas.This paper analyzed the connection between rainfall and volume water content(VWC)of soil at different depths of several soil profiles,and the dynamic feature of groundwater was discussed,which reveals the rainfall infiltration recharge of Quaternary Upper Pleistocene strata.The results show that the Quaternary Upper Pleistocene aquifer groundwater accepts a little direct rainfall recharge,while the lateral recharge is the main supplement source.There were 75 effective rainfall events among 120 rainfall events during the monitoring period,with an accumulated amount of 672.9 mm,and the percentages of effective rainfall amount and duration time were 62.50%and 91.56%,respectively.The max evaporation depth at the upper part in Quaternary cohesive soil was no less than 1.4 m.The soil profile was divided into four zones:(1)The sensitive zone of rainfall infiltration within 1.4 m,where the material and energy exchange frequently near the interface between atmosphere and soil;(2)the buffer zone of rainfall infiltration between 1.4 m and 3.5 m;(3)the migration zone of rainfall infiltration between 3.5 m and 5.0 m;and(4)the rainfall infiltration and groundwater level co-influenced zone below 5.0 m.The results revealed the reaction of soil moisture and groundwater to rainfall in the area covered by cohesive soil under humid climate in Earth’s critical zone,which is of great theoretical and practical significance for groundwater resources evaluation and development,groundwater environmental protection,ecological environmental improvement,drought disaster prevention,and flood disaster prevention in subtropical monsoon climate plain areas.

Effects of Mg content on microstructure and mechanical properties of low Zn-containing Al-xMg-3Zn-1Cu cast alloys

Effects of Mg content on the microstructure and mechanical properties of low Zn-containing Al−xMg−3Zn−1Cu cast alloys(x=3−5,wt.%)were investigated.As Mg content increased in the as-cast alloys,the grains were refined due to enhanced growth restriction,and the formation ofη-Mg(AlZnCu)_(2) and S-Al_(2)CuMg phases was inhibited while the formation of T-Mg_(32)(AlZnCu)_(49 )phase was promoted when Mg content exceeded 4 wt.%.The increase of Mg content encumbered the solution kinetics by increasing the size of eutectic phase but accelerated and enhanced the age-hardening through expediting precipitation kinetics and elevating the number density of the precipitates.As Mg content increased,the yield strength and tensile strength of the as-cast,solution-treated and peak-aged alloys were severally improved,while the elongation of the alloys decreased.The tensile strength and elongation of the peak-aged Al−5Mg−3Zn−1Cu alloy exceed 500 MPa and 5%,respectively.Precipitation strengthening implemented by T′precipitates is the predominant strengthening mechanism in the peak-aged alloys and is enhanced by increasing Mg content.

Effects of Solution Treatment on the Microstructure,Tensile Properties,and Impact Toughness of an Al–5.0Mg–3.0Zn–1.0Cu Cast Alloy

This study investigates the eff ect of solution treatment(at 470°C for 0–48 h)on the microstructural evolution,tensile properties,and impact properties of an Al–5.0Mg–3.0Zn–1.0Cu(wt%)alloy prepared by permanent gravity casting.The results show that the as-cast microstructure consists ofα-Al dendrites and a network-like pattern of T-Mg32(AlZnCu)49 phases.Most of the T-phases were dissolved within 24 h at 470℃;and a further prolonging of solution time resulted in a rapid growth ofα-Al grains.No transformation from the T-phase to the S-Al2CuMg phase was discovered in this alloy.Both the tensile properties and impact toughness increased quickly,reached a maximum peak value,and decreased gradually as the solution treatment proceeded.The impact toughness is more closely related to the elongation,and the relationship between impact toughness and elongation appears to obey an equation:IT=8.43 EL-3.46.After optimal solution treatment at 470℃for 24 h,this alloy exhibits excellent mechanical properties with the ultimate tensile strength,yield strength,elongation and impact toughness being 431.6 MPa,270.1 MPa,19.4%and 154.7 kJ/m^(2),which are comparable to that of a wrought Al–6.0 Mg–0.7 Mn alloy(5E06,a 5 xxx aluminum alloy).Due to its excellent comprehensive combination of mechanical properties,this cast alloy has high potential for use in components which require medium strength,high ductility and high toughness.