Electrochemical behaviour of Ti–25Nb–3Mo–3Zr–2Sn biomedical alloy in different simulated physiological environments

The electrochemical corrosion behaviour of biomedical Ti–25Nb–3Mo–3Zr-2Sn (TLM) alloy was investigated in various simulated body fluids at 37±0·5°C utilising potentiodynamic polarisation and current–time curves. The Ti–6Al–4V (TC4) alloy was also investigated to make a comparison. The different simulated body fluids comprised of 0·9%NaCl saline, Hank’s and Ringer’s solution were employed. The effect of heat treatment on the electrochemical behaviour of the TLM alloy was also considered. It was discovered that all the test specimens were passivated once immersed into the simulated body fluids. It was also found that the TLM alloy has poorer corrosion resistance in Hank’s solution, due to the chemical composition of the Hank’s. After different heat treated, the TLM alloy had different phases and microstructure, and the corrosion behaviour of the TLM alloy was different. In this study, after the heat treatment of 760°C/1 h/AC+550°C/6 h/AC, the TLM alloy had better corrosion resistance. Owing to the corrosion resistance of the TLM alloy was influenced by numerous factors, such as microstructure and the chemical composition of electrolyte, the corrosion behaviour of the TLM alloy is complex. By comparing with the corrosion behaviour of the TC4 alloy, the TLM alloy has poorer corrosion resistant than the TC4 alloy under the same conditions. But the current–time curves of the TLM alloy were more stable than these of the TC4 alloy with further experiments, because of the more passivation film on the surface of the TLM alloy.     

Entrepreneurial quality and regional development: Characterizing SME sectors in low income areas*

This paper analyses the characteristics of SMEs in less‐developed areas in comparison with more advanced economies. The conceptual framework includes different factors making up the so‐called ‘entrepreneurial quality’ of the SME sector: the personal characteristics of the entrepreneurs (motivations and previous experience), different dimensions of the SMEs’ entrepreneurial orientation, and the patterns of the SMEs’ insertion in national and global value chains. The empirical analysis uses data of SMEs in four different Spanish provinces representing examples of low income economies and comparatively high income ones, respectively. Results show the SMEs in the low income economies to be characterized by a lower entrepreneurial quality.     

等温锻造Ti-22Al-25Nb合金的显微组织与力学性能

对Ti-22Al-25Nb(at%)合金在不同相区等温锻造与锻后热处理过程中的组织演变及其对力学性能的影响进行了研究。结果表明,在980℃(B2+α_2+O三相区)、1040℃(α_2+B2两相区)以及1060℃(B2相区)等温锻造并热处理之后,合金的显微组织表现为典型的等轴组织、双态及双尺寸的板条组织,各相的尺寸以及体积分数可以通过热处理制度来控制。合金的力学性能测试表明:双尺寸的板条组织具有较高的室温强度但塑性最低,而等轴组织具有较高的塑性,强度最低。等轴组织的抗蠕变性能最低,双态组织以及双尺寸的板条组织具有相似的抗蠕变性,后两种组织主要以板条组织为主导,板条组织具有比等轴组织更优异的抗蠕变性能。     

低W-W连接度65W-25Cu-10Ni合金的制备及准静态力学性能研究

利用W颗粒表面化学镀Ni结合SPS的方法,制备了低W-W连接度65W-25Cu-10Ni合金,并开展了准静态力学性能研究。结果表明,制得的Ni包W复合粉中Ni包覆层分布均匀且与W结合良好;以Ni包W复合粉和Cu粉为原料制备的65W-25Cu-10Ni合金组织均匀且致密。在准静态压缩加载条件下,与65W-35Cu合金相比,65W-25Cu-10Ni合金的强度及塑性均大幅度提高;在准静态拉伸加载条件下,与65W-35Cu合金相比,65W-25Cu-10Ni合金的强度较高,塑性没有明显提高。机理分析表明,与65W-35Cu合金相比,65W-25Cu-10Ni合金中W-W连接度较低、粘结相由Cu相转变为Cu0.81Ni0.19固溶体,且W与粘结相之间形成了冶金结合,以上三个因素共同导致65W-25Cu-10Ni合金强度的提高;此外,W-W连接度的降低以及W-粘结相界面结合强度的提高是65W-25Cu-10Ni合金在准静态压缩加载条件下塑性提高的原因。     

摇床T25细胞培养瓶流体力学与传质特性研究

细胞培养技术是生物医药产业的支柱,以实现微小体积内的高密度、高通量细胞培养为目的,系统地研究了常用于单层静态培养的T25方瓶置于翘板摇床上在不同操作条件下的流体力学特性和传质性能。结果表明,振荡可以显著提高方瓶的传质速率并降低混合时间,使高密度培养成为可能,但瓶盖上的空气滤膜在高转速时成为传质速率的限制因素;培养瓶对称轴与摇床旋转轴平行时,其相对位置对混合和传质无明显影响,但当二者成45°角时,相同转速下混合时间显著缩短;使用自定义函数实现了基于动态网格的CFD模拟,对不同转速下方瓶内剪切应力和能量耗散在时间与空间上分布进行了分析,为基于T25培养瓶开发一次性高通量微型反应器提供了数据支持和理论基础。     

Identification and In Silico Characterization of a Novel COLGALT2 Gene Variant in a Child with Mucosal Rectal Prolapse

Rectal prolapse is influenced by many factors including connective tissue dysfunction. Currently, there is no data about genetic contribution in the etiology of this disorder. In this study, we performed trio whole-exome sequencing in an 11-year-old girl with mucosal rectal prolapse and her parents and sibling. Genetic testing revealed a novel heterozygous missense variant c.1406G>T; p.G469V in exon 11 of the COLGALT2 gene encoding the GLT25 D2 enzyme. Sanger sequencing confirmed this variant only in the patient while the mother, father and sister showed a wild-type sequence. The pathogenicity of the novel variant was predicted using 10 different in silico tools that classified it as pathogenic. Further, in silico prediction, according to Phyre2, Project HOPE, I-Mutant3.0 and MutPred2 showed that the missense variant can decrease protein stability and cause alterations in the physical properties of amino acids resulting in structural and functional changes of the GLT25D2 protein. In conclusion, the present study identifies a previously unknown missense mutation in the COLGALT2 gene that encodes the enzyme involved in collagen glycosylation. The clinical features observed in the patient and the results of in silico analysis suggest that the new genetic variant can be pathogenic.     

Overexpression of microRNAs miR-25-3p,miR-185-5p and miR-132-3p in Late Onset Fetal Growth Restriction,Validation of Results and Study of the Biochemical Pathways Involved

In a prospective study, 48 fetuses were evaluated with Doppler ultrasound after 34 weeks and classified, according to the cerebroplacental ratio (CPR) and estimated fetal weight (EFW), into fetuses with normal growth and fetuses with late-onset fetal growth restriction (LO-FGR). Overexpression of miRNAs from neonatal cord blood belonging to LO-FGR fetuses, was validated by real-time PCR. In addition, functional characterization of overexpressed miRNAs was performed by analyzing overrepresented pathways, gene ontologies, and prioritization of synergistically working miRNAs. Three miRNAs: miR-25-3p, miR-185-5p and miR-132-3p, were significantly overexpressed in cord blood of LO-FGR fetuses. Pathway and gene ontology analysis revealed over-representation of certain molecular pathways associated with cardiac development and neuron death. In addition, prioritization of synergistically working miRNAs highlighted the importance of miR-185-5p and miR-25-3p in cholesterol efflux and starvation responses associated with LO-FGR phenotypes. Evaluation of miR-25-3p; miR-132-3p and miR-185-5p might serve as molecular biomarkers for the diagnosis and management of LO-FGR; improving the understanding of its influence on adult disease.     

25 Cr2 Ni2 MoV 钢焊接接头低周疲劳性能研究

对新型汽轮机焊接转子材料25Cr2Ni2MoV焊接接头及其母材进行应变控制的低周疲劳试验,并进行了相应的断裂位置统计和循环变形特征分析。试验结果表明,焊接削弱了焊接接头的疲劳强度,受到结构非均匀性和各部分力学性能的相对不匹配等因素的影响,焊接接头的断裂位置体现出明显的应变水平依赖性;焊接接头和母材在循环变形过程中均表现出循环软化特性,且存在明显的拉压不对称性,拉压不对称程度随应变水平的增加而增加;与母材相比,焊接接头表现出更加明显的平均应力松弛现象,且平均应力绝对值随着循环周次不断减小最后趋于常值。     

微观相场法研究沉淀早期两相竞争对筏化的影响

基于微观相场动力学模型,研究沉淀早期不同成分Ni-Al-V合金时效时有序相的生长和组织生长方向的变化。结果表明:沉淀早期有序相间的竞争生长会很大程度地影响合金的形貌及生长方向。在一定的温度、应力场作用下,Al含量较低时,DO22有序相先析出,DO22相颗粒数量较多、尺寸较小,有序相的筏化不明显,合金整体上无显著的筏化现象;Al含量稍高时,L12相先析出,DO22相颗粒数量较少、尺寸较大,组织在[010]方向上发生一定程度的择优生长;Al含量较高时,L12相先析出,DO22相颗粒数量继续减少、尺寸继续增大,组织在[100]方向上显示出较强的筏化趋势;较低温度时效的合金L12有序相析出提前,组织的筏化趋势较弱。     

SiC和Al2O3颗粒对Ti-25Nb-3Mo-3Zr-2Sn合金微磨损行为的影响

本文研究了SiC和Al₂O₃颗粒对生物医用植入材料Ti-25Nb-3Mo-3Zr-2Sn合金的微磨损行为的影响。在文中研究了合金的比磨损率、摩擦系数、磨损机制以及微磨损与腐蚀之间的协同作用。研究结果显示,合金的比磨损率随磨粒尺寸的增加而增加。由于SiC磨粒的硬度和切削性均优于Al₂O₃磨粒,由此在同尺寸磨粒下SiC磨粒所造成的材料的损失比Al₂O₃磨粒造成的要大。摩擦系数的结果显示,在同一种磨粒作用下,Hank’s溶液中所获得的摩擦系数的平均值大于蒸馏水中所获得的摩擦系数平均值,且由于Hank’s溶液的腐蚀性所致在Hank’s溶液中获得的摩擦系数的稳定性要比在蒸馏水中的稳定性差;在同尺寸磨粒下,Al₂O₃磨粒所造成的摩擦系数要大于SiC磨粒所造成的。随磨粒尺寸的减小,磨损机制由三体磨损转变为混合磨损之后再转变为二体磨损。从磨损机制图中可以看出腐蚀对材料损失的贡献是不容小视的,磨损机制为以磨损为主的磨损腐蚀。