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Achieving superior strength-ductility synergy in a heterostructured magnesium alloy via low-temperature extrusion and low-temperature annealing

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Journal of materials Science & Technology 2023年第32期163卷 32-44页

作者： H.Wang d.T.Zhang C.Qiu W.W.Zhang d.L.Chen Guangdong Key Laboratory for Advanced metallic materials Processing and Forming National Engineering Research Center of Near-net-shape Forming for Metallic MaterialsSouth China University of TechnologyGuangzhou 510640China department of mechanical and Industrial Engineering Toronto Metropolitan University(formerly Ryerson University)350 Victoria StreetTorontoON M5B 2K3Canada

A low-alloyed mg-1.2Zn-0.1Ca(wt.%)alloy was fabricated via low-temperature extrusion and annealing at 250℃for different times(10,30,and 90 min)to attain heterostructures with different fine-grained fractions,focusing on the effect of heterostructure on the mechanical *** dynamic recrystallization(RX)occurred during extrusion at 150℃,and a lamellar structure consisting of fine RX grains and coarse unRX grains was *** subsequent annealing promoted static RX in the as-extruded alloy,leading to an increased fine-grained fraction from 67%to 95%.meanwhile,the co-segregation of Zn and Ca atoms impeded the migration of grain boundaries,thus achieving a fine grain size of 0.8–1.6μ*** sample annealed for 10 min with a fine-grained fraction of 73%and an average RX grain size of 0.9μm exhibited a superior combination of high yield strength(305 mPa)and good ductility(20%).In comparison,an excellent elongation of 30%was achieved in the alloy with a nearly fully-RXed microstructure and an average grain size of 1.6μm after 90 min annealing,despite a lower yield strength of 228 *** unRX grains,the hard orientation with(01–10)parallel to the extrusion direction and high-density dislocations made it more difficult to deform compared with the RX grains,thus producing hetero-deformation induced(hdi)*** fine grains and high-density dislocations,hdi strengthening is the key to achieving the superior mechanical properties of the low-alloyed mg alloy.

关键词： Low-alloyed magnesium alloy Low-temperature extrusion Annealing Heterostructure mechanical properties

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Achieving high hetero-deformation induced(hdi)strengthening and hardening in brass by dual heterostructures

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Journal of materials Science & Technology 2022年第3期98卷 244-247页

作者： X.T.Fang Z.K.Li Y.F.Wang m.Ruiz X.L.ma H.Y.Wang Y.Zhu R.Schoell C.Zheng d.Kaoumi Y.T.Zhu department of materials Science and Engineering North Carolina State UniversityRaleighNC 27695USA Key Laboratory for Anisotropy and Texture of materials of ministry of Education Northeastern UniversityShenyang 110819China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China department of materials Science and Engineering Texas A and M UniversityCollege StationTX 77840USA department of mechanical and Aerospace Engineering North Carolina State UniversityRaleighNC 27695USA department of Nuclear Engineering North Carolina State UniversityRaleighNC 27695USA Science and Technology on Thermostructural Composite materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

Heterostructured materials,defined as materials that contain multiple zones with dramatically different flow stresses,have the potential to push the envelope of the strength-ductility of metals and alloys beyond what can be obtained conventionally[1–3].A prominent example is the heterogeneous lamella Ti that is as strong as its ultrafine-grained Ti,while as ductile as the coarsegrained Ti[4].

关键词： grain strengthening deformation

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单剂量丙泊酚注射对慢性每日头痛患者疼痛和生活质量的影响：一项随机双盲对照试验

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麻醉与镇痛 2011年第5期7卷 34-43页

作者： mark K. Simmonds, mB ChB Saifudin Rashiq, Bm BS Igor A. Sobolev, md Bruce d. dick, Phd daniel P. Gray, md Bradley J. Stewart, md Kathryn I. Jamieson-Lega, BSc 苏海华（译） department of Anesthesiology and Pain medicine University of Alberta 600 Hys Centre Edmonton Alberta Canada 不详

背景有少量的病例研究提倡静脉输注丙泊酚来治疗慢性每日头痛（chronicdailyheadache；CdH），然而，尚无该疗法的随机对照试验。在本随机双盲对照试验中，我们的目的是观察单剂量的静脉丙泊酚输注（2．4mg＆g）能否显著降低CdH患者临... 详细信息

背景有少量的病例研究提倡静脉输注丙泊酚来治疗慢性每日头痛（chronicdailyheadache；CdH），然而，尚无该疗法的随机对照试验。在本随机双盲对照试验中，我们的目的是观察单剂量的静脉丙泊酚输注（2．4mg＆g）能否显著降低CdH患者临床不适及接下来30天的疼痛。方法符合标准的CdH成人患者，分别静脉输注丙泊酚（n=20）或安慰剂咪达唑仑（n=20）对照组。主要的结果评估包括：①治疗30天后头痛失劳动力调查评分（HeadachedisabilityInventory；hdi）；②头痛指数（HeadacheIndex，HI），治疗期间30天的头痛强度总评估；③采用用药量化评分表（medicationQuantificationScale，第1II版）评估镇痛药消耗量。结果输注丙泊酚30天后，hdi降低了9．47点（标准差14．1）（P=0．009），但是其降低程度比认为头痛相关失劳动力调查指数（hdi）有临床意义的降低程度更小。与对照组相比，hdi无显著统计差异。在降低平均头痛强度（用头痛指数评估）或用药量化表（medicationQuantification Scale）（第111版）方便，组内及两组间无统计学差异。结论单剂量的丙泊酚静脉输注（2．4mg/kg）产生了有统计学意义的变化，但是在输注药物后30天CdH失劳动力方面的改变无临床意义。丙泊酚也不能减轻头痛强度和减少镇痛药的应用。本研究不支持静脉输注丙泊酚临床治疗CdH。

关键词：随机双盲对照试验慢性每日头痛成人患者单剂量生活质量疼痛酚注射静脉输注

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先进的超声设备能否改善肥胖型孕妇胎心结构显影

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世界核心医学期刊文摘（妇产科学分册） 2005年第1期1卷 12-12页

作者： Hendler I. Blackwell S.C. Treadwell m.C. 李巍 division of ma ternal-Fetal medicine Dept. of Obstetrics and GynecologyHutzelHosp./Wayne Sta te UniversityDetroit MI United States Dr.

Objective This study was undertaken to determine the effect of advanc ed ultras ound equipment on the ability to visualize fetal cardiac structures in obese gra vid women. Study design Singleton pregnancies undergoing initial ultrasound exam ination between 14 weeks and 23 weeks 6 days were included. Patients were classi fied by body mass index (BmI) (nonobese mI m2] and obese mI ≥30 kg/ m2]). The rate of suboptimal ultrasound visualization (SUV) of the fetal heart ( cardiac axis, cardiac position, 4-chamber, and outflow tracts views) was compar ed between patients examined by standard (hdi 3000) or advanced ultrasound equip ment (hdi 5000)-(ATL, Philips medical Systems, Bothell, Wash). Results Over a 5 -year period, 7029 singleton gestations met inclusion criteria; 2498 (35.5%) w ere clinically obese. There was no difference in gestational age, rate of low am niotic fluid volume, anterior placenta, or vertex fetal presentation between the groups. When the advanced ultrasound equipment was used, SUV of the fetal heart was lower in the nonobese population (20.8%vs 16.4%; Pd women (38.1%vs 35.5%; P=.27). However, obese patients who were e xamined by advanced ultrasound equipment after 18 weeks had less SUV of the outf low tracts (28.5%vs 23.1%, P=.04) but not of the 4-chamber view. Conclusion d espite advanced ultrasound equipment,maternal obesity significantly limits visua lization of the fetal heart. However, the advanced ultrasound equipment may some what benefit obese gravid women examined after 18 weeksgestation.

关键词：肥胖型超声设备心脏位置顶先露超声检查前置胎盘羊水量流出道使用标准

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