High thermal conductivity and high strength magnesium alloy for high pressure die casting ultrathin-walled components

With the rapid development of 3C industries,the demand for high-thermal-conductivity magnesium alloys with high mechanical performance is increasing quickly.However,the thermal conductivities of most common Mg foundry alloys(such as Mg-9wt%-1wt%Zn)are still relatively low.In this study,we developed a high-thermal-conductivity Mg-4Al-4Zn-4RE-1Ca(wt%,AZEX4441)alloy with good mechanical properties for ultrathin-walled cellphone components via high-pressure die casting(HPDC).The HPDC AZEX4441 alloy exhibited a fine homogeneous microstructure(average grain size of 2.8μm)with granular Al_(11)RE_(3),fibrous Al_(2)REZn_(2),and networked Ca_(6)Mg_(2)Zn_(3) phases distributed at the grain boundaries.The room-temperature thermal conductivity of the HPDC AZEX4441 alloy was 94.4 W·m^(-1)·K^(-1),which was much higher than 53.7 W·m^(-1)·K^(-1) of the HPDC AZ91D alloy.Al and Zn in the AZEX4441 alloy were largely consumed by the formation of Al_(11)RE_(3),Al_(2)REZn_(2),and Ca_(2)Mg_(6)Zn_(3) phases because of the addition of RE and Ca.Therefore,the lattice distortion induced by solute atoms of the AZEX4441 alloy(0.171%)was much lower than that of the AZ91D alloy(0.441%),which was responsible for the high thermal conductivity of the AZEX4441 alloy.The AZEX4441 alloy exhibited a high yield strength of~185 MPa,an ultimate tensile strength of~233 MPa,and an elongation of~4.2%.This result indicated that the tensile properties were comparable with those of the AZ91D alloy.Therefore,this study contributed to the development of high-performance Mg alloys with a combination of high thermal conductivity,high strength,and good castability.

Statistical Analysis of Students’Learning Effectiveness in Online Courses Offered by British Partners in China-UK Joint Education Program

In the context of internationalization,China-UK Joint Education Programs are receiving increasing attention from universities.Based on the difficulties faced in China-UK Joint Education Program,this paper adopts a questionnaire survey method to study the learning effectiveness of students majoring in digital media technology in the China-UK Joint Education Program at Guangxi University of Finance and Economics,focusing on four aspects:learning materials,learning content,teacher conditions,and student learning outcomes.The research analysis in this paper not only provides strong support for the construction of China-UK Joint Education Program but also offers references for other China-UK Joint Education Programs.

Elevated preoperative plasma D-dimer dose not adversely affect survival of gastric cancer after gastrectomy with curative intent: A propensity score analysis

Objective： Elevated plasma D-dimer has been reported to be associated with advanced tumor stage and poor survival in several types of malignancies. The purpose of this study was to assess the potential impact of preoperative plasma D-dimer level（PDL） on overall survival（OS） of gastric cancer（GC） patients undergoing curative surgery by applying propensity score analysis.Methods： A total of 1,025 curatively resected GC patients in Tianjin Medical University Cancer Institute ＆Hospital were enrolled. Patients were categorized into two groups based on preoperative PDL： the elevated group（EG） and the normal group（NG）. To overcome bias due to the different distribution of covariates for the two groups, a one-to-one match was applied using propensity score analysis, after matching, prognostic factors were analyzed.Results： In analysis for the whole study series, patients in the EG were more likely to have a larger proportion of tumor size ≥5 cm（67.5% vs. 55.8%, P=0.006）, elder mean age（64.0±10.8 years vs. 60.5±11.6 years, P〈0.001） and advanced tumor（T）, node（N）, and TNM stage. Patients with elevated PDL demonstrated a significantly lower 5-year OS than those with normal PDL（27.0% vs. 42.6%, P〈0.001）, however, the PDL was not an independent prognostic factor for OS in multivariate analysis [hazard ratio： 1.13, 95% confidence interval（95% CI）： 0.92–1.39,P=0.236]. After matching, 163 patients in the EG and 163 patients in the NG had the same characteristics. The 5-year OS rate for patients in the EG was 27.0% compared with 25.8% for those in the NG（P=0.809, log-rank）.Conclusions： The poor prognosis of GC patients with elevated preoperative PDL was due to the advanced tumor stage and elder age rather than the elevated D-dimer itself.