Efficacy and safety of ulinastatin in the treatment of septic shock:a systematic review and meta-analysis

Background:Septic shock is a common systemic inflammatory response syndrome for critical patients in the intensive care unit.Ulinastatin is currently used for the treatment of septic shock.Our study sought to evaluate the efficacy and safety of ulinastatin in the treatment of septic shock patients.Methods:Three English databases(Embase,Medline,and Cochrane Library)and four Chinese databases(China National Knowledge Infrastructure,Wanfang data,SinoMed,and VIP)were searched for published randomized controlled trials.Stata 16.0 software was used to conduct the meta-analysis.Results:A total of 48 articles were included(Chinese article 47,1 in English).The results show that the treatment of ulinastatin could reduce mortality(risk ratio=0.63,95%confidence interval(CI)(0.55,0.72)),multiple organ dysfunction syndrome(risk ratio=0.6,95%CI(0.53,0.68)),length of intensive care unit stay(mean difference(MD)=-3.92,95%CI(-4.65,-3.18)),length of hospital stay(MD=-4.39,95%CI(-6.63,-2.15))and decrease Acute Physiology and Chronic Health Evaluation II score(MD=-4.55,95%CI(-5.63,-3.47))and Sequential Organ Failure Assessment score(MD=-2.02,95%CI(-2.59,-1.44))with P<0.001.Moreover,it lowers TNF-α(standardized mean difference(SMD)=-1.78,95%CI(-2.24,-1.32)),Interleukin-6(SMD=-1.17,95%CI(-1.55,-0.8)),C reactive protein(SMD=-1.49,95%CI(-1.99,-0.99)),hypersensitive C-reactive protein(SMD=-1.9,95%CI(-2.87,-0.94))and procalcitonin(SMD=-0.89,95%CI(-1.12,-0.67))levels in the body.Conclusions:Available evidence shows that ulinastatin reduces case mortality rate,multiple organ dysfunction syndrome,length of intensive care unit stay,and length of hospital stay and decreases Acute Physiology and Chronic Health Evaluation II score and Sequential Organ Failure Assessment score.Moreover,it also lowers TNF-α,Interleukin-6,C reactive protein,hypersensitive C-reactive protein,and procalcitonin levels in the body.

Development of diabetic complications and influencing factors among 32653 type 2 diabetes patients:retrospective cohort study using a multi-state Markov

Background:Patients with type 2 diabetes are at high risk for developing multiple chronic complications.However,there is a lack of studies of the cumulative number of diabetic complications in China.Methods:A retrospective cohort study was performed from 2009 to 2021.Type 2 diabetes patients who were first diagnosed after the age of 35 years between January 1,2009,and December 31,2017,were included.Five states were defined according to the number of chronic complications:no(S0),one(S1),two(S2),three(S3),and four or more complications(S4).A multi-state Markov model was constructed to estimate transition probability,transition intensity,mean sojourn time,and the possible factors for each state.Results:The study included 32653 type 2 diabetes patients(mean age,59.59 years;15929(48.8%)male),and mean follow-up time of 7.75 years.In all,4375 transitions were observed.The 12-year transition probability of from state S0 to S1 was the lowest at 16.4%,while that from S2 to S3 was the highest,at 45.6%.Higher fasting blood glucose,lower high-density lipoprotein cholesterol,higher total cholesterol,and an unhealthy diet were associated with higher risk of progression from S0 to S1.Being female,less than 60 years old,weekly physical activity,and vegetarian diet decreased this risk.Being female and less than 60 years old reduced the likelihood of transition from S1 to S2,whereas lower high-density lipoprotein cholesterol increased this likelihood.Conclusions:Following the occurrence of two complications in type 2 diabetes patients,the risk for accumulating a third complication within a short time is significantly increased.It is important to take advantage of the stable window period when patients have fewer than two complications,strengthen the monitoring of blood glucose and blood lipids,and encourage patients to maintain good living habits to prevent further deterioration.

阿柏西普和雷珠单抗治疗糖尿病性黄斑水肿的疗效

目的:比较阿柏西普和雷珠单抗治疗糖尿病性黄斑水肿(DME)的疗效。方法:前瞻性随机对照试验。纳入2020-06/2021-09于我院确诊的非增殖期糖尿病视网膜病变合并DME的患者35例60眼,均采用3+PRN方案行玻璃体腔注射治疗,其中17例30眼接受阿柏西普治疗(阿柏西普组),18例30眼接受雷珠单抗治疗(雷珠单抗组)。随访12mo,观察两组患者中心凹厚度(CMT)和最佳矫正视力(BCVA)情况,记录玻璃体腔注射次数和并发症发生情况。结果:治疗后1、3、6、12mo,阿柏西普组CMT和BCVA均明显优于雷珠单抗组(均P<0.001)。随访期间,阿柏西普组玻璃体腔注射次数少于雷珠单抗组(4.23±0.86次vs 6.40±0.97次,P<0.05),两组患者均未出现药物相关不良反应、眼内感染、血管栓塞等严重并发症。结论:阿柏西普和雷珠单抗治疗DME均具有明确的疗效和安全性,相较于雷珠单抗,阿柏西普可能是DME患者更有效和方便的治疗选择。

Management of regional citrate anticoagulation for continuous renal replacement therapy:guideline recommendations from Chinese emergency medical doctor consensus

Continuous renal replacement therapy(CRRT)is widely used for treating critically-ill patients in the emergency department in China.Anticoagulant therapy is needed to prevent clotting in the extracorporeal circulation during CRRT.Regional citrate anticoagulation(RCA)has been shown to potentially be safer and more effective,and is now recommended as the preferred anticoagulant method for CRRT.However,there is still a lack of unified standards for RCA management in the world,and there are many problems in using this method in clinical practice.The Emergency Medical Doctor Branch of the Chinese Medical Doctor Association(CMDA)organized a panel of domestic emergency medicine experts and international experts of CRRT to discuss RCA-related issues,including the advantages and disadvantages of RCA in CRRT anticoagulation,the principle of RCA,parameter settings for RCA,monitoring of RCA(mainly metabolic acid-base disorders),and special issues during RCA.Based on the latest available research evidence as well as the paneled experts'clinical experience,considering the generalizability,suitability,and potential resource utilization,while also balancing clinical advantages and disadvantages,a total of 16 guideline recommendations were formed from the experts'consensus.

QTL mapping for berry shape based on a high-density genetic map constructed by whole-genome resequencing in grape

Grape berry shape is an important agricultural trait.Clarifying its genetic basis is significant for cultivating grape varieties that meet market demands.However,the current study by forward genetics has not achieved in-depth results.Here,a high-density map was constructed to identify quantitative trait loci(QTLs)for berry shape.A total of 358709 polymorphic SNPs were obtained using whole-genome resequencing(WGS)based on 208 F2 individuals derived from round grape‘E42-6’and oblong grape‘Rizamat’.The 1635.65 cM high-density map was divided into 19 linkage groups with an average distance of 0.37 cM.Using this map,three significant QTLs for fruit shape index(ShI:ratio of berry length to berry width)identified over three years were mapped onto LG4 and LG5,including one stable QTL on Chr5 with the genomic region of 0.47–1.94 Mb.Combining with gene annotation and expression patterns based on RNA-seq data from two contrasting F2 individuals with round and oblong berry(their average ShI was 1.89 and 1.10,respectively)at four developmental stages,four candidate genes were selected from the above QTLs.They were mainly involved in DNA replication,cell wall modification,and phytohormone biosynthesis.Further analysis of RNA-seq data revealed that several important phytohormone synthesis and metabolic pathways were enriched based on differentially expressed genes(DEGs),which was consistent with the results of QTL mapping for genes related to plant hormone biosynthesis in the F2 population.Furthermore,a comparison of plant hormone content showed that there were significant differences in IAA and tZ content between the two contrasting F2 individuals at different developmental stages.Our findings provide molecular insights into the genetic variation in grape berry shape.Stable QTLs and their tightly linked markers offer the possibility of marker-assisted selection to accelerate berry shape breeding.

共同富裕目标下退役军人安置保障能力的评价与强化

共同富裕是社会主义的本质要求,退役军人是共同富裕不可或缺的群体。妥善安置退役军人有利于预防和解决该群体的贫困问题,是关乎新时代国家安全、社会稳定和全民共同富裕的国家重点工程。然而,通过建构指标并进行实证评估发现,当下退役军人安置保障能力存在价值引领偏颇、知识储备欠缺、技术应用生疏等不足,这或许将会对实现共同富裕、维护军队和社会稳定带来潜在风险。论文基于实证分析结果和系统组织理论,设计了退役军人安置保障的多维复合型能力强化模式,该模式以关注退役军人安置保障特点为前提,立足新时代、新机构和新挑战,实施价值、知识和技术的多维度强化,旨在克服退役军人安置保障能力困境并最终达到共同富裕目标。

Application of sequential extraction for analyzing source and sink of uranium in Huanghe River sediments,China

Geochemical behaviors of heavy metals are closely related to their chemical state that can be divided by sequential extraction into exchangeable(F1),bound to carbonates(F2),bound to Fe-Mn oxides(F3),bound to organic matter or sulfide(F4),and residual(F5).Uranium in sediment of the Huanghe(Yellow)River,China,in different chemical states was extracted using the five-step procedure of Tessier and the source and sink were analyzed.Results show that more than 70%of the total uranium was immobile residual F5 in abundance,followed in order of F4>F3>F2>F1,indicating that the main source of uranium in the sediments was from weathered rock in the drainage basin.In addition,the uranium in the sediments presents potential exogenous input in the Lanzhou,Baotou,and Tongguan reach.Fe-Mn oxides are main carriers of unstable uranium,especially those of F1 and F3.Calcite and illite are secondary adsorption minerals of unstable uranium in sediments under natural conditions.Human activities can also produce an obvious impact on uranium speciation.This study provides a reference for the application of sequential extraction in analyzing the source and sink of uranium in river sediments.

Smart Design and Manufacturing the Welded Q350 Steel Frames via Lifecycle Management Strategy of Digital Twin

Artificial intelligent aided design and manufacturing have been recognized as one kind of robust data-driven and data-intensive technologies in the integrated computational material engi-neering(ICME)era.Motivated by the dramatical developments of the services of China Railway High-speed series for more than a decade,it is essential to reveal the foundations of lifecycle man-agement of those trains under environmental conditions.Here,the smart design and manufacturing of welded Q350 steel frames of CR200J series are introduced,presenting the capability and opportu-nity of ICME in weight reduction and lifecycle management at a cost-effective approach.In order to address the required fatigue life time enduring more than 9×10^(6)km,the response of optimized frames to the static and the dynamic loads are comprehensively investigated.It is highlighted that the maximum residual stress of the optimized welded frame is reduced to 69 MPa from 477 MPa of previous existing one.Based on the measured stress and acceleration from the railways,the fatigue life of modified frame under various loading modes could fulfil the requirements of the lifecycle man-agement.Moreover,our recent developed intelligent quality control strategy of welding process mediated by machine learning is also introduced,envisioning its application in the intelligent weld-ing.

Hsa_circ_0136666 mediates the antitumor effect of curcumin in colorectal carcinoma by regulating CXCL1 via miR-1301-3p

BACKGROUND This study investigate the anti-tumor effect of curcumin and whether its mediated by hsa_circ_0136666 through miR-1301-3p/CXCL1 in colorectal carcinoma(CRC).Through multiple experiments,we have drawn the conclusion that curcumin inhibited CRC development through the hsa_circ_0136666/miR-1301-3p/CXCL1 axis,hinting at a novel treatment option for curcumin to prevent CRC development.AIM To determine whether hsa_circ_0136666 involvement in curcumin-triggered CRC progression was mediated by sponging miR-1301-3p.METHODS Cell counting kit-8,colony-forming cell,5-ethynyl-2’-deoxyuridine,and flow cytometry assays were carried out to determine cell proliferation,apoptosis,and cell cycle progression.Real-time quantitative polymerase chain reaction quantified hsa_circ_0136666,miR-1301-3p,and chemokine(C-X-C motif)ligand 1(CXCL1),and western blot analysis determined CXCL1,B-cell lymphoma-2(Bcl-2),and Bcl-2 related X protein(Bax)protein levels.CircBank or starbase software was first used for the prediction of miR-1301-3p binding with hsa_circ_0136666 and CXCL1,followed by RNA pull-down,RNA immunoprecipitation,and dualluciferase reporter assay validation.In vivo experiments were implemented in a murine xenograft model.RESULTS Curcumin blocked CRC cell proliferation but boosted apoptosis.Moreover,elevated hsa_circ_0136666 Levels were observed in CRC cells,which were reduced by curcumin.In vitro,hsa_circ_0136666 overexpression abolished the antitumor activity of CRC cells.Mechanical analysis revealed the ability of hsa_circ_0136666 to sponge miR-1301-3p to modulate CXCL1 levels.CONCLUSION Curcumin inhibited CRC development through the hsa_circ_0136666/miR-1301-3p/CXCL1 axis,hinting at a novel treatment option for curcumin to prevent CRC development.

通风机系列群设计的构思与研究

为了拓宽风机的选型范围,使风机适应更广的运行区间,将离心风机的一些零件设计成通用的,其他零件重新设计,对新旧模型组成一个“离心风机系列群”的可行性进行了研究。文中对一台FRP材料的风机蜗壳做通用设计,更换叶轮及进风口延伸出“高压型”及“大流量型”两款机型。并对两款机型做CFD分析,预测风机性能。再通过选型实例说明“系列群设计法”能拓宽风机的选型范围,在不同的选型工况下选择不同的风机能提高运行工况的效率。实际生产中能通用大量模具,具有很高的实用价值。

Multidrug resistant organism infections in patients with COVID-19:risk factors and outcomes

Background:Coronavirus disease 2019(COVID-19)has now spread to most countries and regions of the world.Risk factors associated with multi-drug resistant organism(MDRO)infections in patients with COVID-19 have not been well studied yet.In the present study,we aimed to identify the risk factors associated with the MDRO infections and their impact on in-hospital mortality of COVID-19 patients.Methods:This retrospective cohort study was conducted between December 2019 and April 2020 at two tertiary hospitals in Wuhan,China.Data of cases were collected through electronic medical records system.This study was focused on cases with bacterial culture records.Risk factors and outcomes associated with MDRO infections were analyzed using logistic regression model.Results:Of the 2891 patients,370 patients have bacterial culture results,and MDROs were isolated in 38 patients.Respiratory tract infections(67.3%)were the most common hospital acquired infections.Variables independently associated with MDRO infections were dyspnea at admission(odds ratio(OR)4.74;95%confidence interval(CI)2.06-10.88;P<0.001),intensive care unit(ICU)admission(OR 5.02;95%CI 1.99-12.63;P<0.01),and invasive mechanical ventilation(OR 5.13;95%CI 2.15-12.27;P<0.001),adjusted for age and gender.MDROs infection was also a significant risk factor of death for the patients,adjusted for age,gender,severity of illness,ICU admission and mechanical ventilation(OR 1.12,95%CI:0.43-2.96,P=0.817).Conclusion:In our study,dyspnea at admission,ICU admission and invasive mechanical ventilation were associated with the presence of MDRO infections,and clinicians should be alert in MDRO infections in COVID-19 hospitalized patients.

Prediction for risk of disease progression among hospitalized COVID-19 patients

Objective:The COVID-19 pandemic poses a significant threat to global health.Given the lack of studies on risk factors for COVID-19 progression at present,this study aimed to build a predictive model to predict the progression risk among hospitalized COVID-19 patients.Methods:We extracted data from 1074 mild and moderate COVID-19 patients from Electronic Health Records(EHRs)in a designated Wuhan hospital including demographic characteristics and clinical and laboratory information.Disease progression was defined as progressing to severe critical illness after admission.The LASSO regression was used to select the predicted variables and a logistic regression model was applied to build the predictive model.Nomogram was used to show the results.Results:Seven variables were included in the predictive model:age per 10 years(OR,1.15;95%CI,1.03-1.29),lactate dehydrogenase(OR,1.73;95%CI,1.14-2.62),neutrophil-to-lymphocyte ratio(OR,2.07;95%CI,1.42-3.02),eosinophil count(OR,2.10;95%CI,1.20-3.69),albumin(OR,2.37;95%CI,1.65-3.45),hemoglobin(OR,1.50;95%CI,1.10-2.05),D-dimer(OR,1.63;95%CI,1.19-2.23).The mean area under the receiver operating characteristic curve of the predictive model was 0.72(95%CI,0.69-0.76).Conclusions:This study built a predictive model that could effectively predict the progression risk among hospitalized COVID-19 patients.

Postoperative decrease of serum albumin predicts shortterm complications in patients undergoing gastric cancer resection

AIM To find an accurate and simple predictor for postoperative short-term complications after gastrectomy. METHODS Two hundred and twenty-three patients undergoing gastric cancer resection between October 1,2015 and September 30,2016 were enrolled in this study. Univariate and multivariate analyses were used toidentify risk factors for complications after gastrectomy. The cutoff values and diagnostic accuracy were examined by receiver operating characteristic curves.RESULTS Sixty-two(27.8%) patients had short-term complications after gastric cancer resection. The postoperative decrease in serum albumin(?ALB) was an independent risk factor for complications(OR = 17.957,95%CI: 6.073-53.095,P < 0.001). The cutoff value was 14.0% and the area under the curve was higher than that of C-reactive protein on postoperative day 3(area under the curve: 0.806 vs 0.709). Patients with ?ALB ≥ 14.0% were more likely to have short-term complications after gastrectomy(46.7% vs 5.0%,P < 0.001),prolonged hospital stay(17.2 ± 10.8 d vs 14.1 ± 4.2 d,P = 0.007) and higher comprehensive complication index(P < 0.001) than those with ?ALB < 14.0%.CONCLUSION Postoperative ?ALB with a cutoff of 14.0% can be used to recognize patients who have high risk of short-term complications following gastric cancer resection.

Assessment of cerebrovascular reserve impairment using the breath-holding index in patients with leukoaraiosis

Many studies have demonstrated that leukoaraiosis is associated with impaired cerebrovascular reserve function. However, the definitive hemodynamic changes that occur in leukoaraiosis are not clear, and there are many controversies. This study aimed to investigate hemodynamic changes in symptomatic leukoaraiosis using transcranial Doppler ultrasonography and the breath-holding test in a Chinese Han population, from northern China. A total of 203 patients who were diagnosed with ischemic stroke or clinical chronic progressive ischemic symptoms were enrolled in this study, including 97 males and 106 females, with an age range of 43-93 years. The severity of leukoaraiosis was evaluated according to the Fazekas grading scale, and patients were divided into four groups accordingly. Grade 0 was no leukoaraiosis, and grades I, II, and III were mild, moderate, and severe leukoaraiosis, respectively, with 44, 79, 44, and 36 cases in each group. Transcranial Doppler ultrasonography and the breath-holding test were performed. The mean blood flow velocity of the bilateral middle cerebral artery was measured and the breath-holding index was calculated. The breath holding index was correlated with leukoaraiosis severity and cognitive impairment. Patients with a low breath holding index presented poor performance in the Montreal Cognitive Assessment (MoCA) and executive function tests. That is, the lower the breath holding index, the lower the scores for the MoCA and the higher for the trail-making test Parts A and B. These results indicate that the breath-holding index is a useful parameter for the evaluation of cerebrovascular reserve impairment in patients with leukoaraiosis. In addition, the breath-holding index can reflect cognitive dysfunction, providing a new insight into the pathophysiology of leukoaraiosis. This study was approved by the Ethics Committee of the Fifth Peoples Hospital of Shenyang, China (approval No. 20160301) and registered in the Chinese Clinical Trial Registry (registration number: ChiCTR1800014421).

Nuclear reprogramming: the zygotic transcription program is established through an“erase-and-rebuild” strategy

卵母细胞显示母亲特定的基因表达式侧面，它被换到当染色质的一个单倍体集合被传递到发展成一个胚胎的受精卵时， zygotic 介绍。位于这抄写 reprogramming 下面的机制当前是未知的。等到当抄写在幼芽的泡卵母细胞被关掉时，一般抄写因素和 transcriptional 管理者的一个范围从染色质被分裂，这里，我们表明那。染色质因素(CF ) 的全球分离破坏在染色质和 CF 之间的物理接触并且在功能的水平导致母亲的抄写节目的檫除。与染色质论坛分开的批评抄写因素和管理者遗体延长了时期，并且立即在专业版以后与染色质成为 re-associated 原子形成。Thisis 由象 DNA 和抄写那样的原子功能的重建跟随了速度集合。我们建议母亲的抄写节目在卵子发生期间被擦掉产生相对天真的染色质， zygotic 抄写节目是在授精以后的重建的重新。这个过程作为“ erase-and-rebuild ”被称为过程，它被用来重设抄写节目，和最可能的其它原子过程也，从母亲的到胚胎的。我们进一步在伴随的纸出现(高 T，等，房间物件 2007；17:135-150 .) 一样的策略也被采用到改编 transcriptional，这在体细胞介绍原子转移和单性生殖，建议这当模特儿在早胚胎开始期间对 transcriptional reprogramming 的所有形式普遍适用。从染色质的 CF 的排水量也为抄写沉默的现象提供解释在期间对 zygotic 转变母亲。

Nanoimprint Lithography:A Processing Technique for Nanofabrication Advancement

Nanoimprint lithography(NIL) is an emerging micro/nano-patterning technique,which is a high-resolution,high-throughput and yet simple fabrication process.According to International Technology Roadmap for Semiconductor(ITRS),NIL has emerged as the next generation lithography candidate for the22 nm and 16 nm technological nodes.In this paper,we present an overview of nanoimprint lithography.The classfication,research focus,critical issues,and the future of nanoimprint lithography are intensively elaborated.A pattern as small as 2.4 nm has been demonstrated.Full-wafer nanoimprint lithography has been completed on a 12-inch wafer.Recently,12.5 nm pattern resolution through soft molecular scale nanoimprint lithography has been achieved by EV Group,a leading nanoimprint lithography technology supplier.

Detection of Asymptomatic Carotid Artery Stenosis in High-Risk Individuals of Stroke Using a Machine-Learning Algorithm

Objective Asymptomatic carotid stenosis(ACS)is closely associated to the incidence of severe cerebrovascular diseases.Early identifying the individuals with ACS and its associated risk factors could be beneficial for primary prevention of stroke.This study aimed to investigate a machine-learning algorithm for the detection of ACS among high-risk population of stroke based on the associated risk factors.Methods A novel model of machine learning was utilized to screen the associated predictors of ACS based on 30 potential risk factors.The algorithm of this model adopted a random forest pattern based on the training data and then was verified using the testing data.All of the original data were retrieved from the China National Stroke Screening and Prevention Project(CNSSPP),including demographic,clinical and laboratory characteristics.The individuals with high risk of stroke were enrolled and randomly divided into a training group and a testing group at a ratio of 4:1.The identification of carotid stenosis by carotid artery duplex scans was set as the golden standard.The receiver operating characteristic(ROC)curve and the area under the curve(AUC)was used to evaluate the efficacy of the model in detecting ACS.Results Of 2841 high risk individual of stroke enrolled,326(11.6%)were diagnosed as ACS by ultrasonography.The top five risk fectors contributing to ACS in this model were identified as family history of dyslipidemia,high level of lowdensity lipoprotein cholesterol(LDL-c),low level of high-density lipoprotein cholesterol(HDL-c),aging,and low body.

Novel approach to GPS/SINS integration for IMU alignment

Strapdown inertial navigation system（SINS） requires an initialization process that establishes the relationship between the body frame and the local geographic reference.This process,called alignment,is generally used to estimate the initial attitude angles.This is possible because an accurate determination of the inertial measurement unit（IMU） motion is available based on the measurement obtained from global position system（GPS）.But the update frequency of GPS is much lower than SINS.Due to the non-synchronous data streams from GPS and SINS,the initial attitude angles may not be computed accurately enough.In addition,the estimated initial attitude angles may have relatively large uncertainties that can affect the accuracy of other navigation parameters.This paper presents an effective approach of matching the velocities which are provided by GPS and SINS.In this approach,a digital high-pass filter,which implements a pre-filtering scheme of the measured signal,is used to filter the Schuler cycle of discrete velocity difference between the SINS and GPS.Simulation results show that this approach improves the accuracy greatly and makes the convergence time satisfy the required accuracy.

A review of biomimetic research for erosion wear resistance

One of the reasons behind failed engineering surfaces and mechanical components is particle erosion wear;thus,to mitigate its happening,biomimetic engineering is the current state-of-the-art being applied.Hence,this paper reviews the literature and the development trends on erosive wear resistance that employ biomimetic methods as well as analyze the bio-inspired surface,the bio-inspired structure,the bio-based materials,the associated challenges,and the future trends.Furthermore,the feasibility of the multi-biological and perspective on the coupling biomimetic method for anti-erosion wear are studied.It is concluded that the design of anti-erosion materials or structures by the bio-inspired methods is of great significance in the development of engineering applications.

Temperature Field and Microstructural Formation of Semi-Solid AlSi_7Mg Alloy

The microstructural formation of the semi-solid AlSi7Mg alloy stirred by electromagnetic field is investigated together withthe tempeatre field of the stirred melt at continuously cooling. A impoat kinetic factor for primny a-Al nucleation is proposed. It isfound that a low temperatUre gradient exists in the electromagnetic stirred melt. This is why the first dendritic arms and secondary de-ndritic arms are refmed. Experimefltal results also show that the root remelting of secontw dendritic arms is an twortat mechanismfor the primary α-Al refmement. Strong electromagnetic stirring greatly reduces the composition supercooling in the melt and eliminatesprefedrig growth of the first dendritic arms. Therefore, many rosettes or spherical Primary α-Al phase particles form finally.