A new insight into LPSO phase transformation and mechanical properties uniformity of large-scale Mg-Gd-Y-Zn-Zr alloy prepared by multi-pass friction stir processing

A large-scale fine-grained Mg-Gd-Y-Zn-Zr alloy plate with high strength and ductility was successfully prepared by multi-pass friction stir processing(MFSP)technology in this work.The structure of grains and long period stacking ordered(LPSO)phase were characterized,and the mechanical properties uniformity was investigated.Moreover,a quantitative relationship between the microstructure and tensile yield strength was established.The results showed that the grains in the processed zone(PZ)and interfacial zone(IZ)were refined from 50μm to 3μm and 4μm,respectively,and numerous original LPSO phases were broken.In IZ,some block-shaped 18R LPSO phases were transformed into needle-like 14H LPSO phases due to stacking faults and the short-range diffusion of solute atoms.The severe shear deformation in the form of kinetic energy caused profuse stacking fault to be generated and move rapidly,greatly increasing the transformation rate of LPSO phase.After MFSP,the ultimate tensile strength,yield strength and elongation to failure of the large-scale plate were 367 MPa,305 MPa and 18.0% respectively.Grain refinement and LPSO phase strengthening were the major strengthening mechanisms for the MFSP sample.In particularly,the strength of IZ was comparable to that of PZ because the strength contribution of the 14H LPSO phase offsets the lack of grain refinement strengthening in IZ.This result opposes the widely accepted notion that IZ is a weak region in MFSP-prepared large-scale fine-grained plate.

数字政府视野下政务服务标准体系建设研究——基于太仓港经济技术开发区行政审批局政务服务标准化试点的实践探究

数字政府建设是提高政府部门服务效能的重要举措。在数字政府建设视野下,政务服务通过数字化、标准化建设,实现质量和效率的双向提升。本文基于太仓港经济技术开发区行政审批局政务服务标准化试点的建设实践,探索构建太仓市港区企业全生命周期标准化政务服务标准体系,系统推进政务服务标准化工作,实现以标准化促进政务服务的高质量发展。

搅拌摩擦加工制备AZ31/CoCrFeNi复合材料的组织、力学性能和磨损性能

采用搅拌摩擦加工工艺制备CoCrFeNi高熵合金颗粒增强AZ31镁基复合材料。采用OM、SEM、EDS和EBSD对复合材料的微观结构进行表征。通过拉伸、显微硬度和干滑动磨损实验研究复合材料的力学性能和磨损性能。结果表明,高熵合金颗粒分布均匀,与镁基体具有良好的冶金结合。复合材料的屈服强度、抗拉强度和硬度分别比母材高80 MPa、46 MPa和HV 54.9。细晶强化是主要的强化机制,对屈服强度的贡献率为43.9%。复合材料的平均摩擦因数由母材的0.331降低到0.240,磨损机制由母材的黏着磨损转变为磨粒磨损。

20mm厚AZ31镁合金厚板搅拌摩擦焊接接头的显微组织演变及强化机制

采用搅拌摩擦焊焊接20mm厚AZ31镁合金板材,并沿厚度方向分5层对接头的显微组织和力学性能进行表征。结果表明:焊接温度和温降速率的不同导致搅拌区晶粒尺寸不均匀,且在材料流动行为的作用下,接头不同区域形成不同强织构。此外,接头各层的屈服强度和抗拉强度从上表面至下表面整体呈逐渐增加的趋势,伸长率沿接头厚度方向首先由9.5%升高至10.5%,然后逐渐降低至6.0%。整体接头的抗拉强度达到母材的88.5%。接头的主要强化机制为细晶强化。

冷喷摩擦复合增材制造6061铝合金的显微组织、力学性能和腐蚀行为

采用冷喷摩擦复合增材制造(CFAM)技术制备6061铝合金块体材料。采用OM、SEM和EBSD对冷喷涂(CS)和CFAM试样的显微组织进行表征,通过显微硬度、拉伸和腐蚀实验研究两者的力学性能和腐蚀行为。结果表明,与CS试样相比,CFAM试样的显微组织更加致密和均匀,晶粒细小等轴,平均晶粒尺寸为3.1μm,显微硬度、极限抗拉强度和伸长率分别提高了22%、171%和683%。CFAM试样的腐蚀电流密度比CS试样低95.1%~97.8%,腐蚀机理由CS试样的点腐蚀转变为晶间腐蚀。

中性粒细胞外泌体中miR⁃15a⁃5p通过靶向抑制BCL2L2促进巨噬细胞凋亡

目的:探讨中性粒细胞外泌体调控巨噬细胞凋亡的可能机制。方法:采用脂多糖诱导中性粒细胞,ELISA检测炎症因子,电镜鉴定外泌体形态,RT‑PCR检测外泌体中miR‑15a‑5p表达;并采用中性粒细胞外泌体与miR‑15a‑5p模拟物分别处理raw267.4巨噬细胞,CCK8检测细胞活力,流式检测细胞凋亡;预测并采用双荧光素酶实验验证miR‑15a‑5p与BCL2L2结合位点;RT‑PCR与Western blot验证miR‑15a‑5p对BCL2L2表达调控。结果:脂多糖诱导的中性粒细胞炎症因子IL‑2、IL‑6、IL‑10与TNF‑α显著升高,电镜观察到外泌体形态特征,miR‑15a‑5p在脂多糖诱导的中性粒细胞外泌体中显著高表达;脂多糖诱导的中性粒细胞外泌体与miR‑15a‑5p模拟物均可以促进raw267.4巨噬细胞凋亡,抑制其细胞活力;Targetscan数据库预测miR‑15a‑5p与BCL2L2具有结合位点,双荧光素酶实验验证miR‑15a‑5p与BCL2L2通过结合位点结合;miR‑15a‑5p模拟物转染raw267.4巨噬细胞后抑制BCL2L2 mRNA与蛋白表达。结论:炎症状态中性粒细胞,可能通过分泌包含miR‑15a‑5p的外泌体,通过靶向抑制BCL2L2进而促进raw267.4巨噬细胞凋亡。这可能为进一步理解中性粒细胞与巨噬细胞炎症调控分子机制提供理论依据。

MiR-15a-5p in neutrophil exosomes promotes macrophage apoptosis through targeted inhibition of BCL2L2

Objective:To explore the possible mechanism of neutrophil exosomes regulating macrophage apoptosis.Methods:neutrophils were induced by lipopolysaccharide,inflammatory factors were detected by ELISA,the morphology of exosomes was identified by electron microscope,and the expression of mir-15a-5p in exosomes was detected by RT-PCR;Raw267.4 macrophages was treated with neutrophil exosomes and mir-15a-5p mimic respectively,CCK8 to detect cell viability,flow cytometry to detect apoptosis;The binding sites of mir-15a-5p and BCL2L2 were predicted and verified by double luciferase experiment;RT-PCR and Western blot verified that mir-15a-5p regulate the expression of BCL2L2.Results:lipopolysaccharide induced neutrophil inflammatory factors IL-2,IL-6,IL-10 and TNF-α.The morphological characteristics of exosomes were observed by electron microscope.Mir-15a-5p was significantly overexpressed in neutrophil exosomes induced by lipopolysaccharide;Lipopolysaccharide-induced neutrophil exosomes and mir-15a-5p simulants can promote raw267.4 macrophage apoptosis and inhibit its cell viability;Targetscan database predicted that mir-15a-5p and BCL2L2 had binding sites.Double-luciferase experiment verified that mir-15a-5p and BCL2L2 bound through binding sites;Mir-15a-5p mimic was transfected into raw267.4 macrophages which inhibit the expression of BCL2L2 mRNA and protein.Conclusion:inflammatory neutrophils may promote raw267.4 by secreting exosomes containing mir-15a-5p and inhibiting BCL2L2 by targeting macrophage apoptosis.This may provide a theoretical basis for further understanding the molecular mechanism of inflammatory regulation of neutrophils and macrophages.

《生物医学英文文献导读》SPOC教学模式研究与实践

《生物医学英文文献导读》是一门面向医科大学新入学硕士的公共选修课,课程目标是帮助学生掌握文献阅读的策略、技巧及方法,教学过程中运用小规模限制性在线课程(Small Private Online Course,SPOC)的模式,给临床医学专业型硕士的学习带来了便利,而从实践过程中总结出的经验和改进方案,为后续SPOC教学模式的完善和推广提供了依据。

基于改进灰色神经网络模型的三峡枢纽过坝货运量预测

针对三峡枢纽过坝货运量预测受多种因素影响及其具有的非线性特点,提出一种基于改进灰色模型和神经网络的组合预测模型。针对传统组合预测模型在赋权上的局限性,提出基于诱导有序加权几何平均(induced ordered weighted geometric averaging,IOWGA)算子的赋权方法。计算结果比较:组合预测模型的均方误差和均方百分比误差都比各单一预测模型的小。利用组合预测模型对2019—2022年三峡枢纽过坝货运量进行了预测,可为相关决策者提供参考。

不同术前胆道引流方式对可切除性恶性梗阻性黄疸种植性转移发生率的影响:Meta分析

目的系统评价不同术前胆道引流方式对可切除性恶性梗阻性黄疸(malignant obstructive jaundice,MOJ)种植性转移发生率的影响。方法计算机检索PubMed、EMbase、Web of Science、Cochrane Library、中国生物医学文献数据库、中国知网、万方及维普数据库,纳入比较可切除性MOJ经皮肝胆道引流(percutaneous transhepatic biliary drainage,PTBD)和经内镜胆道引流(endoscopic biliary drainage,EBD)的种植性转移率的临床对照研究。检索时限均从建库至2017年10月。应用比值比(odds,OR)和95%可信区间(confidence,CI)评价结局指标。用Review Manager 5.3软件进行Meta分析。结果共纳入10项研究,其中PTBD组1 085例、EBD组1 379例。分析结果表明,两种术前胆道引流方式的种植性转移率显著不同(OR 4.91,95%CI 0.23～0.53,P<0.00001)。亚组分析发现,在腹膜种植性转移和导管种植性转移上,EBD组均明显少于PTBD组(OR 3.34,95%CI 0.31～0.74,P=0.0008;OR 4.47,95%CI 0.12～0.44,P<0.00001);并且,这一优势在肝门部胆管癌、远端胆管癌和胰腺癌同时得到验证(OR 2.76,95%CI0.17～0.74,P=0.006;OR 3.50,95%CI 0.17～0.60,P=0.0005;OR 6.62,95%CI 0.19～0.40,P<0.00001)。结论本Meta分析显示,在可切除性MOJ的术前胆道引流的选择上,经内镜胆道引流后种植性转移发生率更低,但目前尚缺乏充足的循证医学证据支持。

Development and calibration of the Moon-based EUV camera for Chang'e-3

The process of development and calibration for the first Moon-based ex- treme ultraviolet （EUV） camera to observe Earth＇s plasmasphere is introduced and the design, test and calibration results are presented. The EUV camera is composed of a multilayer film mirror, a thin film filter, a photon-counting imaging detector, a mech- anism that can adjust the direction in two dimensions, a protective cover, an electronic unit and a thermal control unit. The center wavelength of the EUV camera is 30.2 nm with a bandwidth of 4.6nm. The field of view is 14.7° with an angular resolution of 0.08°, and the sensitivity of the camera is 0.11 count s-1 Rayleigh-1. The geomet- ric calibration, the absolute photometric calibration and the relative photometric cal- ibration are carried out under different temperatures before launch to obtain a matrix that can correct geometric distortion and a matrix for relative photometric correction, which are used for in-orbit correction of the images to ensure their accuracy.

吲哚菁绿荧光显像技术在腹腔镜肝切除术中的应用

目的探讨吲哚菁绿(indocyanine green, ICG)荧光显像技术在腹腔镜肝切除术中的安全性和有效性。方法回顾性分析福建医科大学孟超肝胆医院2018年1月至2019年12月行腹腔镜肝切除术病人的临床资料。采用倾向性评分匹配和Kaplan-Meier生存分析,比较匹配前后两组病人的术中指标(手术时间、出血量、输液量、输血率和切缘情况),术后指标(并发症和住院时间)和预后指标。结果共纳入145例病人,行常规腹腔镜肝切除病人114例(对照组),ICG荧光显像技术引导下腹腔镜肝切除病人31例(研究组)。经1∶1倾向性评分匹配后,两组均有31例病人纳入分析,临床基本特征差异无统计学意义(P>0.05)。匹配后研究组的术中出血量、术中输液量、术后住院时间均显著少于对照组(P<0.05);研究组宽切缘比率多于对照组(P<0.05);两组手术时间、术中输血率、R0切除率、术后并发症和无瘤生存率等差异均无统计学意义(均P>0.05)。结论 ICG荧光显像引导腹腔镜肝切除是一种安全有效的技术,可以获得更好的围手术期收益。

Mechanical and corrosion properties of low-carbon steel prepared by friction stir processing

Low-carbon steel plates were successfully subjected to normal friction stir processing(NFSP) in air and submerged friction stir processing(SFSP) under water, and the microstructure, mechanical properties, and corrosion behavior of the NFSP and SFSP samples were investigated. Phase transformation and dynamic recrystallization resulted in fine-grained ferrite and martensite in the processed zone. The SFSP samples had smaller ferrites(5.1 μm), finer martensite laths(557 nm), and more uniform distribution of martensite compared to the NFSP samples. Compared to the base material(BM), the microhardness of the NFSP and SFSP samples increased by 19.8% and 27.1%, respectively because of the combined strengthening effects of grain refinement, phase transformation, and dislocation. The ultimate tensile strengths(UTSs) of the NFSP and SFSP samples increased by 27.1% and 38.7%, respectively. Grain refinement and martensite transformation also improved the electrochemical corrosion properties of the low-carbon steel. Overall, the SFSP samples had better mechanical properties and electrochemical corrosion resistance than the NFSP samples.

Microstructural evolution and deformation behavior of friction stir welded twin-induced plasticity steel

The weldability of twin-induced plasticity(TWIP)steel with ultra-high strength via friction stir welding(FSW)technique was investigated,and microstructural evolution and deformation behavior of whole and micro-zones of FSW TWIP joint were studied for the first time.The results showed that the content of recrystallized grains in the stir zone(SZ)increased from 10.5%of basal material(BM)to 14.2%,and that of heat affected zone(HAZ)increased to 78.6%.The percentage of annealing twins decreased from 26.8%in BM to 11%in SZ,while increased to 35%in HAZ.Compared with the BM,the ultimate tensile strength and yield strength of the FSW joint increased to 1036 and 550 MPa,respectively,reaching 106.7%and 110.9%of BM,respectively.The elongation of the entire joint was 50.5%,which was lower than that of BM due to the nonuniform deformation during the tensile test.The engineering strain was mainly concentrated in BM and SZ and transferred to each other during the tensile test,while the engineering strain in HAZ was always the lowest.Finally,the tensile fracture occurred in the SZ.The order of ultimate tensile strength of micro-zones in the FSW joint was as follows:HAZ>BM≈SZ.The order of yield strength was as follows:HAZ>BM>SZ.

Microstructure Evolution and Recrystallized Behavior of Friction Stir Welding Twin-Induced Plasticity Steel

The restoration mechanism of twin-induced plasticity(TWIP)steel during friction stir welding(FSW)changed with the degree of the deformation,and the microstructure evolution and dynamic recrystallization are complex and unclear.In this paper,the electron backscattered diffraction and transmission electron microscopy techniques were used to evaluate the dynamic grain structure of FSW joint of TWIP steel.The results showed that the dynamic recrystallization mechanisms in TWIP steel during FSW contained discontinuous dynamic recrystallization(DDRX)and continuous dynamic recrystallization(CDRX).The recrystallization mechanism transitioned from DDRX at the initial deformation stage to DDRX and CDRX at the middle deformation stage,eventually becoming primarily CDRX at the end deformation stage.Numerous annealing twin boundaries(ATBs)were formed within the joint,and the straight ATBs primarily resulted from grain growth accidents,while cluster-shaped ATBs were formed through re-excitations and decomposition of specific grain boundaries.

术前不同胆管引流方式对恶性梗阻性黄疸患者总生存率的影响及其Meta分析

目的系统评价不同术前胆管引流(PBD)方式对恶性梗阻性黄疸(MOJ)患者总生存率的影响及其危险因素分析。方法计算机检索CochraneLibrary、Pubmed、EMbase、中国知网、万方及维普数据库,纳入比较经皮肝胆管引流(PTBD)和经内镜胆管引流(EBD)两组患者总生存率的临床研究。检索时限均从建库至2018年4月30日。应用风险比(HR)和95%可信区间(cI)评价长期生存率,用比值比(on)和95%CI评价影响因素。用ReviewManager5.3软件进行Meta分析。结果共纳入9项研究。其中PTBD组818例、EBD组1253例。分析结果表明,与PTBD相比,EBD组患者具有明显生存优势,两组差异有统计学意义(HR=O.63,95%CI:0.51~O.77,P<0.05)。生存影响因素分析结果显示,EBD组患者病情较轻,表现为早期肿瘤患者比例高(P<0.05)、合并淋巴结转移率低(P<0.05),患者术中出血发生率低(P<0.05)、术后联合化疗的比例高(P<0.05)。结论在MOJ患者术前胆管引流选择方面,EBD在长期疗效上具有优势的结论缺乏足够依据。

经皮胆道支架联合近程放疗治疗恶性梗阻性黄疸:一项多中心、回顾性、对照研究

目的探讨经皮胆道支架联合^(125)I粒子链近程放射治疗(放疗)对恶性梗阻性黄疸的疗效、安全性及影响预后的因素。方法回顾性分析2017年1月至2020年12月收治的107例经皮胆道支架植入治疗的恶性梗阻性黄疸的患者资料,其中58例接受胆道支架联合^(125)I粒子链近程放疗(研究组),49例仅接受胆道支架植入(对照组)。分析两组患者胆红素的变化、支架通畅时间、并发症发生、总生存期(OS)及影响预后因素。结果研究组和对照组并发症的发生率分别为17.2%、18.3%,差异无统计学意义(P=0.974)。两组患者术后1个月血清总胆红素显著降低(P<0.001)。研究组术后支架通畅时间为(10.0±1.6)个月(95%CI:8.2~12.5),显著优于对照组(5.2±0.4)个月(95%CI:4.1~6.0,P<0.001)。研究组中位OS为(11.2±1.8)个月(95%CI:9.2~12.8),较对照组(8.0±1.1)个月更长(95%CI:8.0~12.8,P<0.001)。多因素分析结果表明,支架联合近程放疗(HR=0.08,95%CI:0.04~0.15,P<0.001)和术后接受进一步抗肿瘤治疗(HR=0.27,95%CI:0.15~0.49,P<0.001)是影响胆道支架通畅的独立危险因素;术前经皮肝穿刺胆道引流术治疗(HR=0.46,95%CI:0.28~0.74,P=0.002)、支架联合近程放疗(HR=0.23,95%CI:0.14~0.39,P<0.001)和术后接受进一步抗肿瘤治疗(HR=0.37,95%CI:0.22~0.61,P<0.001)是影响OS的独立危险因素。结论经皮胆道支架联合近程放疗治疗恶性梗阻性黄疸安全有效,可显著延长胆道支架通畅时间及患者的生存时间。

经颈静脉肝内门体分流术联合^(125)I粒子链治疗合并门静脉癌栓肝癌患者的安全性及疗效

目的研究对合并门静脉癌栓肝癌患者采用经颈静脉肝内门体分流术(TIPS)联合^(125)I粒子链植入治疗的安全性及疗效。方法对25例肝内弥漫性肿瘤同时合并Ⅲ/Ⅳ型癌栓需要行TIPS治疗的患者,在TIPS术的同时植入^(125)I粒子链。通过^(125)I粒子链的近程放疗作用控制癌栓来保持TIPS通路通畅,降低门静脉压力,观察患者死亡原因的变化。以同期30例没有行TIPS及^(125)I粒子链植入的患者作对照。组间数据比较采用t检验、Chi-Squre检验或Fisher精确概率法。结果对合并Ⅲ/Ⅳ型门静脉癌栓的弥漫性肝癌患者进行TIPS联合^(125)I粒子链植入操作安全,有92.0%(23/25)患者TIPS通路保持通畅。治疗组与对照组相比,引起患者死亡的并发症种类减少,大多数患者死于慢性肝功能衰竭(84.0%与56.7%,χ^(2)=4.771,P=0.029),发生上消化道出血的例数明显减少(12.0%与46.7%,χ^(2)=7.674,P=0.006);腹水严重程度显著改善(轻度40.0%与16.7%、中度52.0%与20.0%、重度8.0%与46.7%,χ^(2)=13.246,P=0.001)。结论对肝内存在弥漫性肿瘤同时合并Ⅲ/Ⅳ型癌栓患者行TIPS联合植入^(125)I粒子链治疗安全可行,可有效地保持分流道通畅,达到降低门静脉压力从而降低上消化道出血发生率及改善腹水程度的目的。联合^(125)I粒子链植入可能作为需要行TIPS治疗同时合并Ⅲ/Ⅳ型癌栓患者的一种标准治疗模式.

Friction Stir Processing of Magnesium Alloys:A Review

Magnesium(Mg)alloys have been extensively used in various fields,such as aerospace,automobile,electronics,and biomedical industries,due to their high specific strength and stiff ness,excellent vibration absorption,electromagnetic shielding eff ect,good machinability,and recyclability.Friction stir processing(FSP)is a severe plastic deformation technique,based on the principle of friction stir welding.In addition to introducing the basic principle and advantages of FSP,this paper reviews the studies of FSP in the modification of the cast structure,superplastic deformation behavior,preparation of finegrained Mg alloys and Mg-based surface composites,and additive manufacturing.FSP not only refines,homogenizes,and densifies the microstructure,but also eliminates the cast microstructure defects,breaks up the brittle and network-like phases,and prepares fine-grained,ultrafine-,and nano-grained Mg alloys.Indeed,FSP significantly improves the comprehensive mechanical properties of the alloys and achieves low-temperature and/or high strain rate superplasticity.Furthermore,FSP can produce particle-and fiber-reinforced Mg-based surface composites.As a promising additive manufacturing technique of light metals,FSP enables the additive manufacturing of Mg alloys.Finally,we prospect the future research direction and application with friction stir processed Mg alloys.

A case of human infection with a novel Babesia species in China

Background:Babesiosis is an uncommon but emerging tick-borne disease caused by the genus Babesia.In this case study,we report a case of human infection with a novel Babesia sp.in China.Findings:The patient in question had been suffering from repetitive occurrences of mild fever of unknown origin and fatigue for 10 years.Ring forms,tetrads,and one or two dots of chromatin or trophozoite-like organisms were observed in the patient’s thin blood smears and bone marrow smears.Using a confocal laser-scanning microscope,it was observed that the patient’s serum had reactivity with the surface proteins of the B.microti strain.Electron microscopy revealed oval red blood cells with 1~2μm of knob protrusions in the cellular membrane.The results of the Babesia-specific nested PCR assay for 18S rRNA confirmed the presence of Babesia infection.The construction of a phylogenetic relationship showed clustering with B.microti and B.duncani,which was identified as a novel Babesia species and named as Babesia sp.XXB/HangZhou.Azithromycin,doxycycline,and moxifloxacin hydrochloride were shown to relieve symptoms but were not as effective after continuous usage.After atovaquone(Mepron®)administration,the patient recovered from fever and tested negative for detection of Babesia-specific genes.Conclusion:Babesia sp.XXB/HangZhou is a novel Babesia species,which causes mild babesiosis in an immunocompetent patient.