Quench sensitivity and microstructures of high-Zn-content Al−Zn−Mg−Cu alloys with different Cu contents and Sc addition

The Zn,Cu,and Sc contents of 7xxx Al alloys were adjusted according to the chemical composition of a 7085 Al alloy,and the effects of Zn and Cu contents and Sc addition on the microstructures,hardness,and quench sensitivity of the 7xxx Al alloys were studied.The alloys with high Zn content and Sc addition exhibited higher hardness than the 7085 alloy at the position 3 mm away from the quenching end.The density ofηand T phases increased with the increase in Zn and Cu contents,and the Sc addition led to the formation of the Y phase and moreηphases at the position 120 mm away from the quenching end.Compared with the 7085 alloy,the high Zn−high Cu and Sc-added alloys exhibited higher quench sensitivity,while the simultaneous increase in Zn content and decrease in Cu content could enhance the hardness and reduce the quench sensitivity of the 7085 alloy.

Effects of Sc and Zr microalloying on the microstructure and mechanical properties of high Cu content 7xxx Al alloy

The effects of Sc and Zr microalloying on the microstructure and mechanical properties of a 7xxx Al alloy with high Cu content(7055)during casting,deformation,and heat treatment were investigated.The addition of Sc and Zr not only refined the grains but also transformed theθ-phase into the W-phase in the 7055 alloy.Minor Sc and Zr additions enhanced the hardness and yield strength of the 7055-T6 alloy by strengthening the grain boundaries and Al3(Sc,Zr)precipitates.However,a further increase in the Sc and Zr fractions did not refine the grains but instead resulted in the formation of the large-sized W-phase and primary coarse Al3(Sc,Zr)phase and subsequently deteriorated the mechanical properties of the alloys.The 7055 alloy with 0.25Sc addition exhibited the best mechanical property among the prepared alloys.

Ursodeoxycholic acid induces apoptosis in hepatocellular carcinoma xenografts in mice

AIM: To evaluate the efficacy of ursodeoxycholic acid(UDCA) as a chemotherapeutic agent for the treatment of hepatocellular carcinoma(HCC).METHODS: BALB/c nude mice were randomized into four groups 24 h before subcutaneous injection of hepatocarcinoma BEL7402 cells suspended in phosphate buffered saline(PBS) into the right flank. The control group(n = 10) was fed a standard diet while treatment groups(n = 10 each) were fed a standard daily diet supplemented with different concentrations of UDCA(30,50 and 70 mg/kg per day) for 21 d. Tumor growth was measured once each week,and tumor volume(V) was calculated with the following equation: V =(L × W2) × 0.52,where L is the length and W is the width of the xenograft. After 21 d,mice were killed under ether anesthesia,and tumors were excised and weighed. Apoptosis was evaluated through detection of DNA fragmentation with gel electrophoresis and the terminaldeoxynucleotidyl transferase-mediated d UTP-biotin nick end labeling(TUNEL) assay. Western blot analysis was performed to determine the expression of apoptosisrelated proteins BAX,BCL2,APAF1,cleaved caspase-9,and cleaved caspase-3.RESULTS: UDCA suppressed tumor growth relative to controls. The mean tumor volumes were the following: control,1090 ± 89 mm3; 30 mg/kg per day,612 ± 46 mm3; 50 mg/kg per day,563 ± 38 mm3; and 70 mg/kg per day,221 ± 26 mm3. Decreased tumor volumes reached statistical significance relative to control xenografts(30 mg/kg per day,P < 0.05; 50 mg/kg per day,P < 0.05; 70 mg/kg per day,P < 0.01). Increasing concentrations of UDCA led to increased DNA fragmentation observed on gel electrophoresis and in the TUNEL assay(control,1.6% ± 0.3%; 30 mg/kg per day,2.9% ± 0.5%; 50 mg/kg per day,3.15% ± 0.7%,and 70 mg/kg per day,4.86% ± 0.9%). Western blot analysis revealed increased expression of BAX,APAF1,cleaved-caspase-9 and cleaved-caspase-3 proteins,which induce apoptosis,but decreased expression of BCL2 protein,which is an inhibitor of apoptosis,following administration of UDCA. CONCLUSION: UDCA suppresses growth of BEL7402 hepatocellular carcinoma cells in vivo,in part through apoptosis induction,and is thus a candidate for therapeutic treatment of HCC.

Effect of respiratory training apparatus and vibration expectoration vest on expectoration in patients with lung cancer resection

Objective: The aim of this study was to explore the safe and effective method of expectoration in the preoperative period of patients with lung cancer resection and to promote the rehabilitation of patients.Methods: A total of 100 cases of lung cancer patients undergoing elective surgery were divided into the observation group and the control group, with 50 cases in each group. The control group was treated with vibration expectoration vest for expectoration during the perioperative period, and the observation group was treated with respiratory function exerciser that has expectoration function in the perioperative period, three times a day, and the effect was evaluated after 5 days.Results: The number of patients in the observation group after the first expectoration time was significantly less than that of the control group(P<0.001). Pain score, pulmonary atelectasis, and pulmonary infection rate of the observation group were significantly lower than those of the control group;the hospitalization time was significantly shorter than that of the control group; and the difference was statistically significant(P<0.05).Conclusions: Lobectomy for lung cancer patients with perioperative respiratory training for respiratory function exercise, compared with conventional methods, is helpful for postoperative expectoration and to reduce the incidence of adverse events.

Research progress of “shared nurses” under the family community hospital integrated management mode

In order to meet the diverse and multilevel health service needs of the people,following the implementation of the“multi-point practice”of registered physicians by the government in 2009,many pilot projects on the legality of“shared nurses”have been carried out,but there are many difficulties in the process.Through reviewing and researching the relevant literature inland and abroad,this study explores the application of family-community-hospital integrated medical and nursing management model in order to provide a reference for the development and management of“shared nurses”in China.

Preliminary construction of evaluation indicator system for inpatients'nursing service needs in tertiary general hospital

Objectives:To construct a comprehensive evaluation indicator system for inpatients'nursing service needs in tertiary general hospital and to provide evidence for identifying and meeting the needs of inpatients'nursing services.Method:We used the Delphi method to conduct two rounds of expert consultations with 41 experts.Result:The indicator system consisting of 5 first-level indicators and 48 second-level indicators was preliminarily constructed.Conclusions:We formed an evaluation indicator system for inpatients'nursing service needs in tertiary general hospital and classified it into five categories:hospital environment,nursing attitude,nursing skills,information exchange,and emotional support.The indicator system is scientific and reliable.It can provide a basis for nursing staffs to identify and meet the needs of inpatients'care services.

Application of machine learning algorithm for predicting gestational diabetes mellitus in early pregnancy

Objective:To study the application of a machine learning algorithm for predicting gestational diabetes mellitus(GDM)in early pregnancy.Methods:This study identified indicators related to GDM through a literature review and expert discussion.Pregnant women who had attended medical institutions for an antenatal examination from November 2017 to August 2018 were selected for analysis,and the collected indicators were retrospectively analyzed.Based on Python,the indicators were classified and modeled using a random forest regression algorithm,and the performance of the prediction model was analyzed.Results:We obtained 4806 analyzable data from 1625 pregnant women.Among these,3265 samples with all 67 indicators were used to establish data set F1;4806 samples with 38 identical indicators were used to establish data set F2.Each of F1 and F2 was used for training the random forest algorithm.The overall predictive accuracy of the F1 model was 93.10%,area under the receiver operating characteristic curve(AUC)was 0.66,and the predictive accuracy of GDM-positive cases was 37.10%.The corresponding values for the F2 model were 88.70%,0.87,and 79.44%.The results thus showed that the F2 prediction model performed better than the F1 model.To explore the impact of sacrificial indicators on GDM prediction,the F3 data set was established using 3265 samples(F1)with 38 indicators(F2).After training,the overall predictive accuracy of the F3 model was 91.60%,AUC was 0.58,and the predictive accuracy of positive cases was 15.85%.Conclusions:In this study,a model for predicting GDM with several input variables(e.g.,physical examination,past history,personal history,family history,and laboratory indicators)was established using a random forest regression algorithm.The trained prediction model exhibited a good performance and is valuable as a reference for predicting GDM in women at an early stage of pregnancy.In addition,there are cer tain requirements for the propor tions of negative and positive cases in sample data sets when the random forest algorithm is applied to the early prediction of GDM.

Mechanical properties and thermal stability of 7055 Al alloy by minor Sc addition

This study investigated the effect of 0.25 wt%Sc addition on the microstructure and mechanical properties of AA 7055 alloy.The addition of Sc obviously refined the grains of AA 7055 alloy during casting,homogenizing,rolling,solution,and aging treatments due to the formation of primary and precipitate Al3(Sc,Zr)phase.The recrystallization and precipitation of AA 7055 alloy were inhibited during heat treatments by Sc addition.The Sccontaining AA 7055 alloy exhibited higher thermal stability than AA 7055 alloy during homogenizing treatment,because of the grain boundary pinning effect of nano-sized Al3(Sc,Zr)particles.Given its structure characteristics such as fine grains,fineη′phase,and lessηphase,AA 7055 alloy with added Sc showed good mechanical properties after aging at 120℃for 24 h,with an ultimate tensile strength(UTS)of 679 MPa and elongation(EL)of 14%.This work provides an effective strategy to fabricate AlZn-Mg(-Cu)series(7 xxx)alloys with excellent mechanical properties.