Microstructure Evolution and Deformation Mechanisms of As-Cast Antibacterial Ti6Al4V-5Cu Alloy for Isothermal Forging Process

The hot workability behavior of antibacterial Ti6Al4V-5Cu alloy was investigated using a hot compression experiment in the temperature range of 790–1040 °C and strain rate of 10⁻³–10 s⁻¹ with a strain of 0.4. The deformation behavior of the alloy was characterized by Gleeble 3800 compression experiment, and the relationship among deformed microstructures and deformation parameters was established. The deformations of Ti6Al4V-5Cu alloy were temperature and strain rate-dependent. Higher temperature and lower strain rate made power dissipation efficiency (η) increase and reach 89%. The activation energies (Q) in the dual-phase (α + β) and single β phase regions were calculated as 175.43 and 159.03 kJ mol⁻¹, respectively. In the dual (α + β) phase region, with an increase in strain rate, flow-softening behavior was dominated, however in the single β phase region such as processing at 940 °C. Flow stress increased slightly in which work-hardening behavior was dominated (especially between strain rates of 10⁻³–1 s⁻¹). The deformation at various conditions exhibited different stress-strain profiles, providing an insight that work hardening and flow softening coexisted in Ti6Al4V-5Cu alloy. The relative intensity of oscillatory change in flow stress profile decreased as the strain rate decreased. The hot workability of Ti6Al4V-5Cu alloy was also accessed from the viewpoint of the sub-grain structure.     

Electrochemical Evaluation of Stress Corrosion Cracking Susceptibility of Ti-6Al-3Nb-2Zr-1Mo Alloy Welded Joint in Simulated Deep-Sea Environment

Titanium alloys have high specific strength and excellent corrosion resistance and have been applied in deep-sea engineering fields. However, stress corrosion cracking may become one of the biggest threats to the service safety of a high-strength titanium alloy, as well as its weldment. In this work, stress corrosion cracking of a gas-tungsten-arc-welded Ti-6Al-3Nb-2Zr-1Mo (Ti6321) alloy influenced by the applied potentials in simulated deep-sea and shallow-sea environments was investigated by combining slow strain rate testing with electrochemical measurements. The results showed that the service environment and applied potential have a substantial effect on the stress corrosion cracking behavior of the Ti6321 welded joint. The Ti6321 welded joint exhibited higher stress corrosion susceptibility in a simulated deep-sea environment and at a strong polarization level owing to the diminishing protection of the passive film under passivation inhibition and the enhancement of the hydrogen effect. The fracture of a Ti6321 welded joint in the weld material could be attributed to the softening effect of the thick secondary α within the coarse-grained martensite. The electrochemical evaluation model of stress corrosion cracking susceptibility of a Ti6321 welded joint in a simulated marine environment was established by adding the criterion in the passivation region based on the literature model, and four potential regions corresponding to different stress corrosion cracking mechanisms were classified and discussed. Our study provides useful guidance for the deep-sea engineering applications of Ti6321 alloys and a rapid assessment method of stress corrosion risk.     

X线与CT诊断空洞型肺结核的价值分析

目的 探讨分析X线与CT诊断空洞型肺结核的价值.方法 在本院2016年2月~2017年2月间接诊的空洞型肺结核患者中随机选取50例作为本次研究的对象,对患者先后进行X线与CT检查,采用X线方式检查的为A组,采用CT方式检查的为B组.比较两种检查方法的差异性及临床诊断应用价值.结果 在50例确诊的患者中,常规X线胸片检查结果显示20例26个空洞,其中厚壁空洞11例,虫蚀样空洞2例,薄壁空洞7例;常规CT检查结果显示50例74个空洞,其中厚壁空洞32例,虫蚀样空洞4例,薄壁空洞14例.B组发现空洞个数及类型数量明显多于A组,两组间比较差异有统计学意义(P<0.05).B组的检查结果中发现空洞、卫星病灶、支气管播散、胸膜增厚、淋巴肿大、胸腔积液等个数明显多于A组,两组间比较差异有统计学意义(P<0.05).B组在病变分布检查中共检出128例,总检出率为93.4%,明显高于A组的64例和46.7%,两组间比较差异有统计学意义(P<0.05).B组病变隐藏部位的检出个数为25个,检出率为100.0%,明显高于A组的2个和8.0%的检出率,两组间比较差异有统计学意义(P<0.05).结论 CT诊断空洞型肺结核与X线相比较更加全面、清晰、准确,具有较高的临床应用价值.     

黄芪及其复方制剂含量测定方法的研究概况

黄芪(Astragalus Lepsensis Bge)以豆科紫云属膜荚黄芪(Astragalus M em branceus Fisch Bge)或蒙古黄芪(A,m ongholicus Bge)的干燥根作为正品使用。该药具补气固表、脱疮生肌和强心利尿等作用,可用于治疗体虚自汗、久泻等病症[1]。黄芪还具有增强免疫系统、抗氧化、延缓衰老、改善心功能状态、抗病毒、抗癌等功效[2]。黄芪的化学成分众多,主要有皂甙类、黄酮类、多糖类以及氨基酸类等,其不同的化学成分具有不同的药理活性。因此我们对近些年黄芪中活性成分的含量测定作简要概述。1皂甙类物质的含量测定黄芪中数种皂甙成分经过醇制氢氧…     

直接测定红细胞平均血红蛋白含量在贫血诊断中的应用

目的探讨直接测定红细胞平均血红蛋白含量(celluarHb,CHb)在贫血诊断中的意义。方法通过全自动血液分析仪检测健康人群及不同类型贫血患者的CHb,并进行ROC曲线分析。结果CHb的正常参考范围是27.74～31.21pg;除了正常细胞均一性贫血患者的CHb与健康人群无显著性差异(P>0.05)外,下述四类贫血患者的CHb与健康人群均有极显著性差异(P<0.01):在大细胞均一性贫血诊断时,若以CHb>31.2pg为分界值,其敏感度0.94、特异性0.99、诊断效率0.97;在大细胞不均一性贫血诊断时,以CHb>31.2pg为分界值,其敏感度1.00、特异性0.99、诊断效率0.99;在诊断正常细胞不均一性贫血时,以CHb<29.4pg为分界值:敏感度0.62、特异性0.54、诊断效率0.57;在诊断小细胞性贫血时,以CHb<27.2pg为分界值,诊断敏感度1.00、特异性1.00、诊断效率1.00。结论直接测定能真实反映机体红细胞血红蛋白含量,结合合适的分界值,在各种贫血的诊断与鉴别诊断中,尤其是小细胞性贫血,CHb是一项理想的诊断指标,值得进一步推广应用。     

Differential temporal neural responses of pain-related regions by acupuncture at acupoint ST36: a magnetoencephalography study

Background  Previous neuroimaging studies primarily focused on the spatial distribution of acupuncture needling stimulation. However, a salient feature of acupuncture was its long-lasting effect. This study attempted to detect the spatial-temporal neural responses evoked by acupuncture at an analgesia acupoint ST36 by using magnetoencephalography. To further verify its functional specificity, we also adopted acupuncture at Pericardium 6 and nonacupoint as separated controls.

Methods  Forty-two college students, all right-handed and acupuncture naïve, participated in this study. Every participant received only one acupoint stimulation, resulting in 14 subjects in one group. Both magnetoencephalography data (151-channel whole-head system) and structural functional magnetic resonance imaging data (3D sequence with a voxel size of 1 mm³ for anatomical localization) were collected for each subject. All processing procedures were performed in BrainStorm Toolbox.

Results  Acupuncture at ST36 showed a significantly time-varied brain activities with different onset time. Our results presented that acupuncture at different acupoints (or comparing with nonacupoint) can specifically induce neural responses in different brain areas—acupuncture at ST36 can specifically induce the neural responses of pain-inhibition areas, while acupuncture at PC6 can specifically induce the activities of the insula and amygdala.

Conclusions  In the present study, we attempted to detect the temporal neural responses underlying the functional specificity of acupuncture at ST36, using acupoint belonging to different meridians and non-acupoint with efficacy-irreverent as separate controls. The specific neural substrates involving acupuncture at different acupoints may be related to its functional specificity in clinical settings.

     

缺血性脑损伤后多巴胺和5羟色胺含量的变化

对沙土鼠(gerbil)进行单侧颈总动脉结扎,做成单侧脑缺血的动物模型,运用高效液相色谱电化学检测仪测定,研究额叶皮质区、尾状核区、海马区内神经递质多巴胺及5羟色胺在恢复过程中不同存活期内的含量变化,其中下降最显著的在海马组内,损伤侧DA下降到仅占对照侧的33%,P<0.01(第七天);在尾状核组内,5HT下降到仅占对照侧的38%,P<0.01(第七天),但额叶皮质组内二者变化不显著,为防治脑血管疾患提供了客观指标。     

Rational design of M–N4–Gr/V2C heterostructures as highly active ORR catalysts: a density functional theory study

Inspired by the composites of N-doped graphene and transition metal-based materials as well as MXene-based materials, heterostructures (M–N₄–Gr/V₂C) of eight different transition metals (M = Ti, Cr, Mn, Fe, Co, Ni, Cu, and Zn) doped with nitrogen-coordinated graphene and V₂C as potential catalysts for the oxygen reduction reaction (ORR) using density functional theory (DFT) were designed and are described herein. The calculations showed that the heterostructure catalysts (except for Zn–N₄–Gr/V₂C) were thermodynamically stable. Ni–N₄–Gr/V₂C and Co–N₄–Gr/V₂C showed higher activities towards the ORR, with overpotentials as low as 0.32 and 0.45 V, respectively. Excellent catalytic performance results were observed from the change in electronic structure caused by the strong interaction between V₂C and the graphene layers as well as the synergistic effect between the MN₄ groups and the graphene layers. This study further provides insights into the practical application of ORR catalysts for MXene systems through the modulation of the electronic structure of two-dimensional materials.

Heterostructures (M-N₄-Gr/V₂C) of eight different transition metals (M = Ti, Cr, Mn, Fe, Co, Ni, Cu and Zn) were designed as potential catalysts for oxygen reduction reactions (ORR).     

应用ATPase组化法及TEM法对皮肤癣菌病患者表皮郎格罕细胞的观察

本文应用ATPase组化方法首次对30例皮肤癣菌病患者皮损表皮及70例对照者相应部位表皮作了郎格罕细胞(LC)观察,并对其中3例患者及1例对照者表皮LC作了透射电镜(TEM)观察。结果发现患者表皮LC形态改变、数量减少或消失及细胞超微结构受损;且上述改变程度随病变范围扩大及病程延长而加重。本文首次提出LC与皮肤癣菌病的免疫病理改变有密切关系,可能皮肤癣菌的入侵使表皮LC受损,从而干扰了T淋巴细胞诱导的机体对病原体的清除功能。本文还讨论了两种方法的注意点。