Microstructure Evolution of Al6061 Alloy Made by Additive Friction Stir Deposition

In this paper, the phase structure, composition distribution, grain morphology, and hardness of Al6061 alloy samples made with additive friction stir deposition (AFS-D) were examined. A nearly symmetrical layer-by-layer structure was observed in the cross section (vertical with respect to the fabrication-tool traversing direction) of the as-deposited Al6061 alloy samples made with a back-and-forth AFS-D strategy. Equiaxed grains were observed in the region underneath the fabrication tool, while elongated grains were seen in the “flash region” along the mass flow direction. No clear grain size variance was discovered along the AFS-D build direction except for the last deposited layer. Grains were significantly refined from the feedstock (~163.5 µm) to as-deposited Al6061 alloy parts (~8.5 µm). The hardness of the as-fabricated Al6061 alloy was lower than those of the feedstock and their heat-treated counterparts, which was ascribed to the decreased precipitate content and enlarged precipitate size.     

Optimizing the Thermomechanical Process of Nickel-Based ODS Superalloys by an Efficient Method

Thermo-mechanical process of nickel-based oxide dispersion strengthened (ODS) superalloys is critical to produce desired components. In this study, an efficient method of consolidating powder is introduced to optimize the preparation process, microstructure and properties of nickel-based ODS superalloys. The influences of consolidation temperature, strain rate and ball milling time on the hardness of nickel-based superalloys were studied. The relationship among process, microstructure and hardness was established, the nanoparticles strengthening and grain boundary strengthening in nickel-based ODS superalloys were discussed. The results indicate that long ball milling time, moderately low consolidation temperature and high strain rates are beneficial to improving properties of nickel-based superalloys. Moreover, dispersion strengthening of nanoparticles and grain boundary strengthening play important roles in enhancing nickel-based ODS superalloys.     

Quantitative Distribution Characterization and Correlation Study of Composition,Structure and Hardness of Rim Region in Railway Wheel

The railway wheel is the key component of high-speed railway train. To assure the safety in service, higher requirements are put forward in this study for the composition, microstructure uniformity, and comprehensive properties of wheel materials. In this paper, the high throughput quantitative distribution characterization methods of composition, microstructure, inclusions and Vickers hardness of high-speed railway wheel materials based on the spark source original position analysis technique, high throughput scanning electron microscope (SEM) combined with image batch processing technology, and automatic two-dimensional quantitative distribution analysis technique of inclusions and micro hardness have been studied. The distribution trend of the content of nine elements, size and quantity of sulfides and oxides, ferrite area fraction, and Vickers hardness from the wheel tread surface to the radial depth of about 50 mm below the surface has been discussed. The influence of inclusions distribution on the element segregation and the effect of rim-chilling process with different water spraying angle on the distribution of microstructure and micro hardness have been investigated. It was found that unsynchronized cooling on both sides of the rim altered the phase behavior of ferrite and pearlite and obvious inhomogeneity distribution of ferrite appeared, which led to the asymmetrical Vickers hardness in areas near or away from the flange. Based on the quantitative characterization of area fraction and micro hardness on the same location of wheel rim, a statistical mapping relationship between ferrite area fraction and Vickers hardness was established.     

HBV-DNA定量、肝脏硬度值与乙肝肝硬化并食管胃静脉曲张出血内镜治疗后早期再出血的相关性研究

目的 通过检测乙肝肝硬化并食管胃静脉曲张出血(EVB)经内镜治疗后患者的HBV-DNA定量、肝脏硬度值,探讨该两项指标对EVB内镜治疗后早期再出血的临床应用价值。方法 选取2016年8月—2018年7月行内镜治疗的EVB患者,根据治疗后是否发生早期出血分为出血组(27例)、未出血组(201例),记录两组患者HBV-DNA定量、肝脏硬度值并比较。对可能导致EVB术后再出血的风险因素进行赋值,然后行Logstic回归分析,对EVB术后再出血的风险因素进行初步探讨。通过描绘受试者工作曲线(ROC)观察HBV-DNA定量、肝脏硬度值与预测内镜治疗后再出血的相关性,并对上述指标联合检测的特异性、敏感度进行计算,观察上述指标联合检测的价值。结果 (1)本次研究的228例EVB患者中,有27例术后出现了早期再出血现象,EVB内镜治疗后早期再出血率为11.84%。(2)早期再出血患者HBV-DNA含量、肝脏硬度值显著高于未出血患者,两组比较有统计学意义(P＜0.01)。(3)Logistic回归分析显示:HBV-DNA、肝脏硬度值、空腹血糖、曲张静脉数量是EVB术后早期再出血的风险因子。(4)通过描绘ROC曲线发现,HBV-DNA含量、肝脏硬度值联合检测能显著提高预测EVB术后再出血的敏感度、特异性。结论 HBV-DNA定量、肝脏硬度值在EVB术后再出血患者中明显升高,是早期再出血的影响因子,临床上可通过HBV-DNA定量、肝脏硬度值检测评估EVB术后再出血风险。     

不同消毒方法对碳离子改性硅橡胶表面自由能及邵氏硬度的影响

目的 初步探讨碳离子硅橡胶经过不同消毒试剂与方法处理后其表面亲疏水性、表面自由能以及邵氏硬度的变化情况.方法 碳离子硅橡胶经过70％酒精、2％碱性戊二醛、0.5％碘伏、5.25％次氯酸钠、3％过氧化氢以及134℃高温、高压等消毒试剂或方法处理后,采用静态接触角测定仪检测其表面水、甘油接触角以及邵氏硬度变化情况,采用Owen-Wendt公式计算表面自由能γs、极性分量γsp以及非极性分量γsd变化.结果 碳离子硅橡胶经过5.25％次氯酸钠以及3％过氧化氢处理后,其表面接触角以及表面自由能发生明显变化,前者使得其表面呈现出完全的亲水性;70％酒精、2％碱性戊二醛、0.5％碘伏以及134℃高温、高压等方法对材料表面接触角以及表面自由能等影响较小.不同处理组材料表面邵氏硬度差异均无统计学意义.结论 70％酒精以及134℃高温、高压等消毒方法对碳离子硅橡胶表面性能影响最小,结合操作便利性等因素,70％酒精可认为是该材料最适宜的消毒处理方式.而次氯酸钠消毒液极不利于该材料表面形貌维持,不宜采用.     

软坚散结法治疗痰瘀交结型高脂血症性脂肪肝的临床疗效观察

【目的】观察具有软坚散结作用的经验方心脉康片治疗痰瘀交结型高脂血症性脂肪肝的临床疗效及安全性。【方法】采用分层随机原则将64例痰瘀交结型高脂血症性脂肪肝患者随机分成试验组和对照组,每组各32例。2组患者均予禁酒以及对饮食、运动和生活规律进行指导的常规处理,在此基础上,对照组给予阿托伐他汀钙片治疗,试验组给予阿托伐他汀钙片联合心脉康片治疗,疗程为12周。观察2组患者治疗前后血脂[总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)]、肝功能指标[谷丙转氨酶(ALT)/谷草转氨酶(AST)]和腹部B超评分的变化情况,并评价2组的中医证候疗效及安全性。【结果】(1)研究过程中,试验组和对照组分别有1例和2例患者退出,实际纳入研究试验组31例,对照组30例。(2)中医证候疗效方面,疗程结束后,试验组的总有效率为87.09%,对照组为73.33%,试验组的疗效明显优于对照组(P<0.05)。(3)血脂方面,治疗后,2组患者的TC、TG、LDL-C水平均较治疗前降低,HDL-C水平均治疗前升高(P<0.05),且试验组对TC、TG、LDL-C水平的降低作用和对HDL-C水平的升高作用均明显优于对照组(P<0.05)。(4)B超评分方面,治疗后,2组患者的B超评分均较治疗前明显降低(P<0.05),且试验组对B超评分的降低作用明显优于对照组(P<0.05)。(5)治疗后,2组患者的血清ALT、AST水平均较治疗前明显降低(P<0.05);但治疗后组间比较,差异均无统计学意义(P>0.05)。(6)观察过程中,2组患者的血常规、离子、肌酶、肾功能等均未见明显异常。【结论】心脉康片治疗痰瘀交结型高脂血症性脂肪肝,疗效确切且安全性高,初步证明软坚散结法是治疗痰瘀交结型高脂血症性脂肪肝的一种新思路和新方法。     

超声弹性成像技术联合血清学标志物预测2型糖尿病的应用价值

<正>多项研究表明,非酒精性脂肪性肝病患者(NAFLD)发生2型糖尿病(type 2 diabetes mellitus,T2DM)的风险是正常人的5倍^[1-3]。在T2DM患者中,NAFLD的患病率可高达70%^[4]。肝脏瞬时弹性成像技术(tran-sient elastography,TE)是近年来新兴的超声无创检查方法,主要基于超声信号在肝组织中传播受肝细胞中脂滴的影响而出现显著衰减的原理来评估肝脏脂肪性病变,     

The effect of different storage media on the monomer elution and hardness of CAD/CAM composite blocks

ObjectiveThis study aimed to assess the effect of different storage media on the hardness and monomer elution of CAD/CAM composite blocks.MethodsFive resin-composite blocks (RCB), one polymer-infiltrated ceramic network (PICN) block (Enamic (EN)), one ceramic-filled poly ether ether ketone (PEEK) block (Dentokeep (DK)), and one feldspathic ceramic block. Microhardness was measured using a Vickers indenter tester (FM-700, Future Tech Corp., Japan). In addition 4 conventional resin-composites were investigated for monomer elution using high performance liquid chromatography (HPLC) after storage in different media for 3 months. The data were analysed by three-way ANOVA, two-way ANOVA, one-way ANOVA, Tukey’s post hoc test and the independent t-test (α = 0.05 for all tests).ResultsThe specimens stored in the water had a hardness reduction ranging from 0.9% to 24.4%. In artificial saliva, the specimens had a hardness reduction ranging from 2.8% to 23.2%. The hardness reduction percentage in 75% Ethanol/Water (E/W) ranged between 3.8% and 35.3%. All materials, except GR (resin-composite block) and DK (Polyetheretherketone (PEEK)), showed a variable extent of monomer elution into 75% E/W with significantly higher amounts eluted from conventional composites. GRA and GND (conventional resin-composites) eluted TEGDMA in artificial saliva and GRA eluted TEGDMA in water.SignificanceThe hardness of CAD/CAM composite blocks was affected by different storage media, and they were not as stable as ceramic, with PICN exhibited superior hardness stability to all of the resin-composite blocks in all the storage media and was comparable to ceramic block. The hardness reduction percentage of the CAD/CAM composite blocks was influenced by the filler loading and resin-matrix composition.Minimal or no monomer elution from CAD/CAM blocks was detected.     

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目的探讨偏振数码照相结合计算机辅助图像分析法评价邻面去釉后釉质脱矿程度的准确性。方法于2010年3月选取青岛大学医学院附属医院口腔外科门诊因正畸需要拔除的上颌第一前磨牙40颗,沿牙冠颊舌向磨切得到80个标本,随机分为A（空白对照,未进行任何去釉处理）、B（邻面去釉）、C（邻面去釉后使用氟化泡沫）、D（邻面去釉后使用护牙素）4组。体外pH循环60d后,用偏振数码照相结合计算机辅助图像分析法定量测量各组标本邻面去釉及再矿化后的灰度值,以此来评价其釉质脱矿程度。同时用显微硬度仪定量测量各组标本的硬度值作为对照。结果（1）灰度值：A组灰度值最低,B组灰度值最高,C组和D组经过再矿化处理后灰度值较B组降低,差异有统计学意义（P〈0．05）。c组和A、D组之间灰度值差异无统计学意义（P〉0．05）。（2）硬度值：A组硬度值最高,B组硬度值最低,c组和D组经过再矿化处理后硬度值升高,但均较A组低。B组硬度值和其他3组之间比较,差异均有统计学意义（P〈0．05）,而A组与c组、c组与D组之间硬度值比较,差异均无统计学意义（P〉0．05）。结论偏振数码照相结合计算机辅助图像分析法得出的结果与显微硬度仪的定量检测结果相符合,表明了其是一种有效的定量评价釉质脱矿及再矿化效果的方法,值得临床推广。     

NiTi根管器械表面耐磨镀层的制备和性能研究

目的：研究镍钛合金表面耐磨镀层的制备工艺和性能,提高镍钛根管器械的表面硬度和耐磨性。方法：采用直流电镀法在NiTi合金表面制备了Ni—W合金镀层,通过能谱分析和X射线衍射技术（XRD）研究电镀工艺对Ni—W耐磨镀层成分和结构的影响。采用销一盘式摩擦试验机对耐磨Ni—W合金镀层的耐磨性进行测试,通过磨损失重和磨痕形貌观察评价和分析了Ni—W合金镀层的耐磨性和耐磨机理。结果：在NiTi合金表面所制备的Ni—W合金耐磨镀层的W含量在15．2．20．2wt％范围内,且镀层致密,无微观裂纹。Ni—W合金镀层的结构是W在Ni中的固溶体。与Ni—Ti合金基体相比,镀有Ni—W合金镀层的Ni—B合金试样的磨损失重大幅度降低,耐磨性显著提高;Ni—W合金镀层的硬度和耐磨性随镀层中W含量的增加而增大。结论：直流电镀技术对镍钛合金根管器械进行表面改性可显著提高其耐磨忡．