Effect of Sn content on microstructure and tensile properties of as-cast and as-extruded Mg-8Li-3Al-(1,2,3)Sn alloys

The effects of Sn content on microstructure and tensile properties of as-cast and as-extruded Mg-8Li-3Al-(1,2,3)Sn(wt.%)alloys were investigated by X-ray diffractometry(XRD),optical microscopy(OM),scanning electron microscopy(SEM)and tensile test.It is found that,as-cast Mg-8Li-3Al-(1,2,3)Sn alloys consist ofα-Mg+β-Li duplex matrix,MgLiAl2 and Li2Mg Sn phases.Increasing Sn content leads to grain refinement ofα-Mg dendrites and increase in content of Li2MgSn phase.During hot extrusion,complete dynamic recrystallization(DRX)takes place inβ-Li phase while incomplete DRX takes place inα-Mg phase.As Sn content is increased,the volume fraction of DRXedα-Mg grains is increased and the average grain size of DRXedα-Mg grains is decreased.Increasing Sn content is beneficial to strength but harmful to ductility for as-cast Mg-8Li-3Al-(1,2,3)Sn alloys.Tensile properties of Mg-8Li-3Al-(1,2,3)Sn alloys are improved significantly via hot extrusion and Mg-8Li-3Al-2Sn alloy exhibits the best tensile properties.

A liquid loading prediction method of gas pipeline based on machine learning

The liquid loading is one of the most frequently encountered phenomena in the transportation of gas pipeline,reducing the transmission efficiency and threatening the flow assurance.However,most of the traditional mechanism models are semi-empirical models,and have to be resolved under different working conditions with complex calculation process.The development of big data technology and artificial intelligence provides the possibility to establish data-driven models.This paper aims to establish a liquid loading prediction model for natural gas pipeline with high generalization ability based on machine learning.First,according to the characteristics of actual gas pipeline,a variety of reasonable combinations of working conditions such as different gas velocity,pipe diameters,water contents and outlet pressures were set,and multiple undulating pipeline topography with different elevation differences was established.Then a large number of simulations were performed by simulator OLGA to obtain the data required for machine learning.After data preprocessing,six supervised learning algorithms,including support vector machine(SVM),decision tree(DT),random forest(RF),artificial neural network(ANN),plain Bayesian classification(NBC),and K nearest neighbor algorithm(KNN),were compared to evaluate the performance of liquid loading prediction.Finally,the RF and KNN with better performance were selected for parameter tuning and then used to the actual pipeline for liquid loading location prediction.Compared with OLGA simulation,the established data-driven model not only improves calculation efficiency and reduces workload,but also can provide technical support for gas pipeline flow assurance.

Synthesis of dandelion-like TiO_2 microspheres as anode materials for lithium ion batteries with enhanced rate capacity and cyclic performances

Dandelion-like TiO2 microspheres consisting of numerous rutile single-crystalline nanorods were synthesized for the first time by a hydrothermal method. Their crystal structure, morphology and electrochemical properties were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and galvanostatic charge and discharge tests. The results show that the synthesized TiO2 microspheres exhibit good rate and cycle performances as anode materials of lithium ion batteries. It can be found that the dandelion-like structure provides a larger specific surface area and the single-crystalline nanorod provides a stable structure and fast pathways for electron and lithium ion transport, which contribute to the rate and cycle performances of the battery.

System design and measurements of flux concentrator and its solid-state modulator for CEPC positron source

Positron sources are one of the most important components of the injector of a circular electron positron collector(CEPC).The CEPC is designed as an e^(+)e^(−)collider for a Higgs factory.Its accelerator system is composed of 100-km-long storage rings and an injector.The design goal of the positron source is to obtain positron beams with a bunch charge of 3 nC.The flux concentrator(FC)is one of the cores of the positron source.This paper reports the design,development,and measurements of an FC prototype system.The prototype includes an FC and an all-solid-state high-current pulse modulator.Preliminary tests show that the peak current on the FC can reach 15.5 kA,and the peak magnetic field can reach 6.2 T.The test results are consistent with the theoretical simulation.The FC system fulfills the requirements of the CEPC positron source as well as provides a reference for the development of similar devices both domestically and abroad.

Microscopic characterization of semi-solid aluminium alloys

The microstructural evolution and element distribution of the Al-4Cu-Mg alloy during semi-solid compression were investigated, and the precipitate behavior and dislocation morphology were discussed. The experimental results show that the microstructure, the number of CuAl2 （θ phase） precipitates, and the dislocation density of the Al-4Cu-Mg alloy depend apparently on the process parameters. More segregation of Cu at the grain boundary happens with an increase of deformatinn temperature and a decrease of strain rate, leading to an increase in the number of θ phase. With an increase of height reduction, Cu segregation at the grain boundary decreases gradually. Moreover, unique dislocation morphologies including helical dislocations and dislocation loops appear at different process parameters and evolve to reduce the stored energy.

Observation on clinical application effect of ankle rehabilitation robot

Objective:The effect of ankle rehabilitation robot on joint movement of hemiplegic patients was studied and quantitatively evaluated.Methods 90 hemiplegic patients with lower limb dysfunction treated in our hospital from April 2017 to March 2019 were selected as subjects.The patients were randomly divided into two groups:control group(n=45)and observation group(n=45).The patients in the two groups received language training,physiotherapy,exercise therapy,spa,occupational therapy,massage and other comprehensive rehabilitation treatment,on the basis of which the observation group received the auxiliary intervention of ankle rehabilitation robot.The soft tissue compliance of the patients was evaluated by ankle metatarsal flexion moment before and after treatment,the metatarsal flexor tension was evaluated by modified Tardieu scale,and the clinical effect was evaluated by ankle active ankle dorsiflexion.Results After treatment,the ankle flexion angles(0°,10°,20°,30°)in the two groups were significantly lower than those in the control group(P<0.05).Results compared with before treatment,the ankle flexion angles(0°,10°,20°,30°)in the two groups were significantly lower than those in the control group(P<0.05).After treatment,the angle of R1 and R2 measured by modified Tardieu scale of ankle plantar flexor group increased significantly,and the difference of R2-R1 decreased significantly(P<0.05).The improvement degree of the observation group was significantly better than that of the control group(P<0.05).After treatment,the active ankle extension activity of the two groups was significantly higher than that before treatment(P<0.05),and the effective rate of the observation group was significantly higher than that of the observation group(P<0.05).Conclusion Auxiliary intervention with ankle rehabilitation robot system can effectively improve the compliance of ankle soft tissue in spastic hemiplegia,reduce the contracture of metatarsal flexor muscle and improve the disturbance of joint movement in a short time.At the same time,the degree of coordination and acceptance of patients and their families is high,which is an effective means to improve the therapeutic effect.

西藏各地市健康人群H.pylori菌感染状况分析

目的了解目前西藏地区人群幽门螺旋杆菌(Helicobacter pylori, H. pylori)的感染状况,为西藏地区幽门螺杆菌感染的防治提供临床数据.方法回顾2017年于西藏自治区人民政府驻成都办事处医院就诊且同时完成13C-尿素呼气试验的西藏地区体检者,收集临床资料、常居留地及H. pylori检测结果等.结果共纳入931例病例, H. pylori总体阳性率为480/931(51.6%,95%C I:48.3%-54.8%),其中藏族586例, H.pylori阳性率为331/586(56.5%,95%CI:52.5%-60.5%);汉族345例, H.pylori阳性率为149/345(43.2%,95%CI:37.9%-48.4%).藏汉族之间H.pylori阳性率存在显著差异(P <0.001).西藏地区各地市的H. pylori阳性率分别为:拉萨市99/219(45.2%,95%C I:38.6%-51.8%),昌都市213/372(57.3%,95%C I:52.2%-62.3%),林芝市56/110(50.9%,95%CI:41.4%-60.4%),山南市25/63(39.7%,95%CI:27.3%-52.1%),日喀则市21/51(41.2%,95%C I:27.2%-55.2%),那曲地区17/40(42.5%,95%C I:26.5%-58.5%),阿里地区49/76(64.5%,95%C I:53.5%-75.5%),各地市之间的H.pylori阳性率存在差异(P=0.002).结论西藏地区H. pylori现患率已下降趋于全国水平,藏汉族之间现患率存在差异,各地市H. pylori现患率亦存在差异.

Neoadjuvant chemotherapy for locally advanced cervical cancer reduces surgical risks and lymph-vascular space involvement

Neoadjuvant chemotherapy(NACT),which can reduce the size and therefore increase the resectability of tumors,has recently evolved as a treatment for locally advanced cervical cancer.NACT has been reported to decrease the risk of pathologic factors related to prognosis of cervical cancer.To further assess the effects of NACT on surgery and the pathologic characteristics of cervical cancer,we reviewed 110 cases of locally advanced cervical cancer treated with radical hysterectomy with or without NACT at the People's Hospital of Peking University between January 2006 and December 2010.Of 110 patients,68 underwent platinum-based NACT prior to surgery(NACT group) and 42 underwent primary surgery treatment(PST group).Our results showed 48 of 68(70.6%) patients achieved a complete response or partial response to NACT.Estimated blood loss,operation time,and number of removed lymph nodes during surgery,as well as complication rates during and after surgery were not significantly different between the NACT group and the PST group.The rates of deep stromal invasion,positive parametria,positive surgical vaginal margins,and lymph node metastasis were not significantly different between the two groups.However,the rate of lymph-vascular space involvement(LVSI) was significantly lower in the NACT group than in the PST group(P = 0.021).In addition,the response rate of NACT was significantly higher in the patients with chemotherapeutic drugs administrated via artery than via vein.Our results suggest that NACT is a safe and effective treatment for locally advanced cervical cancer and significantly decreases the rate of LVSI.

Neuroprotective effects of SMAds in a rat model of cerebral ischemia/reperfusion

Previous studies have shown that up-regulation of transforming growth factor β1 results in neuroprotective effects. However, the role of the transforming growth factor β1 downstream molecule, SMAD2/3, following ischemia/reperfusion remains unclear. Here, we investigated the neuroprotective effects of SMAD2/3 by analyzing the relationships between SMAD2/3 expression and cell apoptosis and inflammation in the brain of a rat model of cerebral ischemia/reperfusion. Levels of SMAD2/3 mRNA were up-regulated in the ischemic penumbra 6 hours after cerebral ischemia/reperfusion, reached a peak after 72 hours and were then decreased at 7 days. Phos- phorylated SMAD2/3 protein levels at the aforementioned time points were consistent with the mRNA levels. Over-expression of SMAD3 in the brains of the ischemia/reperfusion model rats via delivery of an adeno-associated virus containing the SMAD3 gene could reduce tumor ne- crosis factor-a and interleukin-lβ mRNA levels, down-regulate expression of the pro-apoptotic gene, capase-3, and up-regulate expression of the anti-apoptotic protein, Bcl-2. The SMAD3 protein level was negatively correlated with cell apoptosis. These findings indicate that SMAD3 exhibits neuroprotective effects on the brain after ischemia/reperfusion through anti-inflamma- tory and anti-apoptotic pathways.

Mitogen-activated protein kinase phosphatase 1 protects PC12 cells from amyloid beta-induced neurotoxicity

The mitogen-activated protein kinase（MAPK） signaling pathway plays an important role in the regulation of cell growth, proliferation, differentiation, transformation and death. Mitogen-activated protein kinase phosphatase 1（MKP1） has an inhibitory effect on the p38 MAPK and JNK pathways, but it is unknown whether it plays a role in Aβ-induced oxidative stress and neuronal inflammation. In this study, PC12 cells were infected with MKP1 sh RNA, MKP1 lentivirus or control lentivirus for 12 hours, and then treated with 0.1, 1, 10 or 100 μM amyloid beta 42（Aβ42）. The cell survival rate was measured using the cell counting kit-8 assay. MKP1, tumor necrosis factor-alpha（TNF-α） and interleukin-1β（IL-1β） m RNA expression levels were analyzed using quantitative real time-polymerase chain reaction. MKP1 and phospho-c-Jun N-terminal kinase（JNK） expression levels were assessed using western blot assay. Reactive oxygen species（ROS） levels were detected using 2′,7′-dichlorofluorescein diacetate. Mitochondrial membrane potential was measured using flow cytometry. Superoxide dismutase activity and malondialdehyde levels were evaluated using the colorimetric method. Lactate dehydrogenase activity was measured using a microplate reader. Caspase-3 expression levels were assessed by enzyme-linked immunosorbent assay. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase d UTP nick end labeling method. MKP1 overexpression inhibited Aβ-induced JNK phosphorylation and the increase in ROS levels. It also suppressed the Aβ-induced increase in TNF-α and IL-1β levels as well as apoptosis in PC12 cells. In contrast, MKP1 knockdown by RNA interference aggravated Aβ-induced oxidative stress, inflammation and cell damage in PC12 cells. Furthermore, the JNK-specific inhibitor SP600125 abolished this effect of MKP1 knockdown on Aβ-induced neurotoxicity. Collectively, these results show that MKP1 mitigates Aβ-induced apoptosis, oxidative stress and neuroinflammation by inhibiting the JNK signaling pathway, thereby playing a neuroprotective role.

Microstructure and mechanical properties of as-extruded Mg-Sn-Zn-Ca alloy with different extrusion ratios

The effect of extrusion ratio on microstructure and mechanical properties of as-extruded Mg-6Sn-2Zn-1Ca （TZX621）（mass fraction, %） alloy was investigated. It is found that incomplete dynamic recrystallization （DRX） took place in as-extrudedTZX621 alloy. As the extrusion ratio was increased from 6 to 16, both fraction of un-DRXed grains and average size of DRXedgrains in as-extruded TZX621 alloy decreased and the basal texture was weakened. Coarse CaMgSn phase was broken into particlesand fine Mg2Sn phase precipitated from α-Mg matrix during hot extrusion. Yield strength, ultimate tensile strength and elongation ofas-extruded TZX621 alloy with extrusion ratio of 16 reached 226.9 MPa, 295.6 MPa and 18.1%, which were improved by 36.0%,17.7% and 13.5%, respectively, compared to those of as-extruded TZX621 alloy with extrusion ratio of 6.

Serum gastrin-17 concentration for prediction of upper gastrointestinal tract bleeding risk among peptic ulcer patients

BACKGROUND Serum gastrin-17(G-17),pepsinogen I(PGI),and pepsinogen II(PGII)concentrations regulate gastric acid secretion,and hypersecretion of gastric acid increases the risks of peptic ulcer and upper gastrointestinal bleeding.These associations suggest that serum G-17,PGI,and(or)PGII may predict gastrointestinal bleeding risk among peptic ulcer patients.AIM To evaluate the efficacies of serum G-17,PGI,PGII,and PGI/PGII ratio(PGR)for predicting upper gastrointestinal bleeding among peptic ulcer patients.METHODS A total of 199 patients diagnosed with peptic ulcer confirmed by gastroscopy and positivity for Helicobacter pylori by the 14C-urea breath test were recruited,including 107 patients with simple peptic ulcer and 92 cases complicated by upper gastrointestinal bleeding.Serum PGI,PGII,G-17,and PGR were measured by immune methods and compared between bleeding and non-bleeding groups by univariate analysis.The specificity and sensitivity of PGs and G-17 for evaluating upper gastrointestinal bleeding risk were then assessed by constructing receiver operating characteristic(ROC)curves.RESULTS Serum G-17 was significantly higher among peptic ulcer patients with upper gastrointestinal bleeding compared to simple peptic ulcer patients(25.34±14.29 vs 8.84±8.03 pmol/L,t=9.822,P<0.01),whereas serum PGI,PGII,and PGR did not differ significantly between bleeding and non-bleeding groups(all P>0.05).The risk of bleeding was significantly higher among peptic ulcer patients with elevated serum G-17(>15 pmol/L)compared to patients with normal or low serum G-17(73.2%vs 27.4%,χ2=40.72,P<0.01).The area under the ROC curve for serum G-17 was 0.866±0.024,and a cut-off of 9.86 pmol/L yielded 90.2%sensitivity and 68.2%specificity for distinguishing peptic ulcer with and without upper gastrointestinal bleeding.CONCLUSION Serum G-17 is significantly upregulated in peptic ulcer patients and higher levels are predictive of upper gastrointestinal bleeding.Conversely,serum PGI,PGII,and PGR have no predictive value.Further prospective studies are warranted to examine if high G-17 can be used to assess risk of bleeding prior to onset.

Development of Preparation Systems with K_2CsSb Photocathodes and Study on the Preparation Process

The next generation of advanced light sources requires photons with large average flux and high brightness,which needs advanced electron gun matched with excellent photocathode materials. K_2CsSb photocathode has the advantages of high quantum efficiency, long lifetime and instantaneous response. This study introduces the design of a set of K_2CsSb photocathode preparation systems and detailed preparation process of K_2CsSb photocathodes, including sequential deposition process and co-deposition process, and finally develops a K_2CsSb photocathode. The influence of laser power on the quantum efficiency is also investigated.

Microstructure evolution and mechanical properties of rheo-squeeze casting AZ91-Ca alloy during heat treatment

The rheo-squeeze casting(RSC)process is a newly-developed casting process for high-performance components.In order to further improve the mechanical properties of magnesium alloys,AZ91-2wt.%Ca(AZX912)alloy was prepared by the RSC process and then subjected to heat treatment.The microstructure evolution and mechanical properties of AZX912 alloy during heat treatment were investigated.It was found that during solid solution treatment at 410°C,β-Mg_(17)Al_(12) phase with low melting point dissolves intoα-Mg matrix,while the connected network-like Al_2Ca phase with high melting point tends to separate gradually,and the tips of Al_2Ca phase is partially spheroidized.With the increase of solid solution time,the yield strength(YS)of AZX912 alloy decreases gradually while the ultimate tensile strength(UTS)and elongation to failure(E_f)increase continuously.Isothermal ageing at 225°C promotes the precipitation ofβ-Mg_(17)Al_(12) phase in the matrix of AZX912 alloy.The hardness reaches the peak after ageing for 96 h and the increase in hardness is about 24.8%.The precipitation ofβ-Mg_(17)Al_(12) phase during ageing treatment is beneficial to YS but harmful to E_f.The mechanism of microstructure evolution during heat treatment and its effect on mechanical properties are discussed.

Microstructure and mechanical properties of AZ91-Ca magnesium alloy cast by different processes

The microstructure and mechanical properties of magnesium （Mg） alloys are significantly influenced by the casting process. In this paper, a comparative study on microstructure and mechanical properties at ambient and elevated temperatures of AZ91-2wt.% Ca （AZX912） Mg alloy samples prepared by gravity casting （GC）, squeeze casting （SC） and rheo-squeeze casting （RSC）, respectively, was carried out. The results show that mMg grains in SC and RSC samples are significantly refined compared to the GC sample. The average secondary dendritic arm spacing of AZX912 alloy samples decreases in the order of GC, SC and RSC. As testing temperature increases from 25 ~C to 200 ~C, strength of AZX912 alloy samples is reduced, while their elongation is increased continuously. Compared to GC and SC processes, RSC process can improve the mechanical properties of AZX912 alloy at both ambient and elevated temperatures. The enhancement of mechanical properties of RSC sample over GC and SC samples mainly results from grain refinement in the as-cast microstructure of AZX912 alloy.

Multiple left ventricular myxomas combined with severe rheumatic valvular lesions: A case report

BACKGROUND Primary cardiac tumors are uncommon,of which cardiac myxoma accounts for 50%-80%.Left ventricular myxoma has been rarely reported,accounting for only 3%-4%of all cardiac myxomas.Multiple left ventricular myxomas are,relatively,even rarer.CASE SUMMARY In this report,we present a case of multiple left ventricular myxomas combined with severe rheumatic valve lesions.Symptomatically,the patient presented with fatigue,shortness of breath,and palpitation after activities.The patient underwent complete surgical resection of multiple left ventricular myxomas combined with mechanical replacement of the mitral and aortic valves,tricuspid valvuloplasty.The patient recovered well after the operation,with no obvious related complications.CONCLUSION Multiple left ventricular myxomas may coexist with severe rheumatic valve disease.Operation is an effective treatment.

可控震源地震资料中的谐波畸变及消除

基于升频扫描定义,针对瞬时频率随时间呈线性变化的情况,L_1等(1995)提出了一个确定性的纯相移滤波器(PPSF)以消除可控震源地震资料中的谐波畸变。应用PPSF有可能改善谐振畸变的地面压力信号与谐振畸变的可控震源信号间的相关。这种PPSF已成功地应用于实际资料。本文中,我们首先通过对谐波畸变扫描(HDS)的傅里叶相位谱及它的分量进行数值计算,并将它们与相应的瞬时相位进行比较来研究可控震源资料。我们提供了时间域和频率域内谱之间的一些有意义的关系。我们还论证了这些关系将如何对利用PPSF消除谐波畸变的方法起作用。最后,我们给出了利用PPSF消除谐波畸变过程的数学模型。

Waveguide distribution system of the HEPS linac

Purpose The High-Energy Photon Source(HEPS)is a 6 GeV storage ring-based light source under construction in Beijing,China.Its accelerator consists of a 6 GeV storage ring,a full-energy booster,an S-band normal-conducting 500 MeV linac,and three transport lines.As the beginning of HEPS,a stable linac is quite important,which needs a qualified waveguide distribution system to transmit microwave power from klystrons to accelerating structures.Methods Installation and high-power conditioning of the HEPS linac were performed from February to September 2022.The assembly and conditioning of the waveguide distribution system were completed in April and July,respectively.The design of the waveguide distribution system began in 2018 and was finalized at the end of 2020 after multiple iterations.Results Owing to careful design,fabrication,and assembly preparation,the assembly and conditioning of the system proceeded smoothly and considerable time was saved.Conclusion The entire process from the design to the ultimate realization of the system is introduced in detail in this paper.Satisfactory measurement results were obtained for some waveguide components.

用全波地震资料现场计算Q_p—log

本文介绍了一种传统的用全波声波资料(FWS)现场计算视纵波衰减因子的修正方法。衰减因子(Q_p^(-1))可以在两个频率点处用远近两个接收器组的傅里叶频谱比来求取。这种方法的优点是我们不必知道如何校正频谱的几何扩散损失。 修正后的方法已经成功地应用于FWS资料。此FWS资料是在Oberpfalz地区KTB井(德国大陆超深钻井计划)随钻测量时记录的。此法产生了比频谱法更为稳定的结果,使我们可以获得连续的等间隔的衰减因素Q_p的测井曲线Q_p—log。Q_p—log可以提供地震波沿井壁传播衰减的详细信息。它可以和其它声测井(τ_p—log)及用VSP资料估算的衰减等对比,以取得更佳的地震波衰减的岩性解释结果。

Identification of new fusion genes and their clinical significance in endometrial cancer

Background:Fusion genes may play an important role in tumorigenesis, prognosis, and drug resistance;however, studies on fusion genes in endometrial cancer (EC) are rare. This study aimed to identify new fusion genes and to explore their clinical significance in EC. Methods: A total of 28 patients diagnosed with EC were enrolled in this study. RNA sequencing was used to obtain entire genomes and transcriptomes. STAR-comparison and STAR-fusion prediction were applied to predict the fusion genes. Chi-square tests and Student t tests were used to verify the clinical significance with SPSS 13.0 software. Results: New fusion genes were found, and the number of fusion genes varied from 3 to 110 among all patients with EC. The type of fusion genes varied and included messenger RNA (mRNA)-mRNA, long non-coding RNA (lncRNA)-lncRNA, and lncRNAmRNA. There were six fusion genes with high fusion rates, namely, RF11-123010.4-GRIP1-RP11-444D3.1-SOXS,RP11-680G10.1-GSE1,NRIP1-AF127936.7,RP11-96H19.1-RP11-446N19.1,andDPH7-PTP4A3. Further studies showed that these fusion genes are related to stage, grade, and recurrence, in which NRIP1-AF127936.7andDPH7-PTP4A3 were found only in stage Ⅲ patients with EC. DPH7-PTP4A3was found in grades 2 and 3, and recurrent patients with EC. Conclusion: Fusion genes play an essential role in EC. Six genes that are overexpressed with high fusion rates are identified. NRIP1-AF127936.7and DPH7-PTP4A3 might be related to stage, and DPH7-PTP4A3 be related to grade and recurrence.