Numerical Modeling and Analysis of Ti6Al4V Alloy Chip for Biomedical Applications

The influence of cutting forces during the machining of titanium alloys has attained prime attention in selecting the optimal cutting conditions to improve the surface integrity of medical implants and biomedical devices. So far, it has not been easy to explain the chip morphology of Ti6Al4V and the thermo-mechanical interactions involved during the cutting process. This paper investigates the chip configuration of the Ti6Al4V alloy under dry milling conditions at a macro and micro scale by employing the Johnson-Cook material damage model. 2D modeling, numerical milling simulations, and post-processing were conducted using the Abaqus/Explicit commercial software. The uncut chip geometry was modeled with variable thicknesses to accomplish the macro to micro-scale cutting by adapting a trochoidal path. Numerical results, predicted for the cutting reaction forces and shearing zone temperatures, were found in close approximation to experimental ones with minor deviations. Further analyses evaluated the influence of cutting speeds and contact friction coefficients over the chip flow stress, equivalent plastic strain, and chip morphology. The methodology developed can be implemented in resolving the industrial problems in the biomedical sector for predicting the chip morphology of the Ti6Al4V alloy, fracture mechanisms of hard-to-cut materials, and the effects of different cutting parameters on workpiece integrity.     

p53-Ser~(392)的磷酸化在肿瘤治疗中的作用

磷酸化是p53转录后修饰最常见的方式,但对p53-Ser392的磷酸化在肿瘤治疗中的作用及具体机制知之甚少。我们就p53-Ser392的磷酸化状态对野生型及突变型p53功能的影响、放疗化疗因素及蛋白激酶对p53-Ser392的磷酸化水平的调节和p53-Ser392的磷酸化研究意义进行了阐述。     

Tumor Necrosis Factor and Interleukin‐6 Gene Polymorphisms and Endometriosis Risk in Asians: A Systematic Review and Meta‐Analysis

A relationship between endometriosis and tumor necrosis factor (TNF‐α) and interleukin‐6 (IL‐6) gene polymorphisms has been raised for Asians. However, this topic is controversial. This study was a meta‐analysis to explore whether TNF‐α/IL‐6 gene polymorphisms were associated with a risk of endometriosis in Asians. By searching PubMed, HuGENet, and China National Knowledge Infrastructure (CNKI) databases, 17 studies were identified and included (3372 cases and 4008 controls). The odds ratio (OR) with 95% confidence interval (CI) was used to assess the association between TNF‐α/IL‐6 gene polymorphisms and endometriosis risk. An association of TNF‐α gene ‐1031T/C polymorphism with endometriosis was found (TT + TC vs. CC: OR 0.50, 95% CI 0.30–0.82, I² = 37.1%, P = 0.20; TT vs. CC: OR 0.50, 95% CI 0.30–0.82, I² = 43.0%, P = 0.173; TC vs. CC: OR 0.49, 95% CI 0.29–0.83, I² = 10.6%, P = 0.327). In addition, TNF‐α‐238A/G and IL‐6 ‐174C/G gene polymorphisms were also likely to be associated with endometriosis in Asians. For the TNF‐α‐238A/G gene polymorphism, the OR was 1.577 (95% CI: 1.01–2.48). For the IL‐6 ‐174C/G gene polymorphism, the OR was 1.554 (95% CI: 1.04–2.31). No associations were detected between the TNF‐α‐308A/G and IL‐6 ‐634C/G polymorphisms and susceptibility to endometriosis. Our results indicate that the TNF‐α gene ‐1031T/C polymorphism can reduce the risk of endometriosis, but for Asians, TNF‐α‐238A/G and IL‐6 ‐174C/G gene polymorphisms may be a risk factor for endometriosis. No association was found for the TNF‐α‐308A/G and IL‐6 ‐634C/G gene polymorphisms.     

Gene expression profiles in granuloma tissue reveal novel diagnostic markers in sarcoidosis

Sarcoidosis is an immune-mediated multisystem disease characterized by the formation of non-caseating granulomas. The pathogenesis of sarcoidosis is unclear, with proposed infectious or environmental antigens triggering an aberrant immune response in susceptible hosts. Multiple pro-inflammatory signaling pathways have been implicated in mediating macrophage activation and granuloma formation in sarcoidosis, including IFN-γ/STAT-1, IL-6/STAT-3, and NF-κB. It is difficult to distinguish sarcoidosis from other granulomatous diseases or assess disease severity and treatment response with histopathology alone. Therefore, development of improved diagnostic tools is imperative. Herein, we describe an efficient and reliable technique to classify granulomatous disease through selected gene expression and identify novel genes and cytokine pathways contributing to the pathogenesis of sarcoidosis. We quantified the expression of twenty selected mRNAs extracted from formalin-fixed paraffin embedded (FFPE) tissue (n = 38) of normal lung, suture granulomas, sarcoid granulomas, and fungal granulomas. Utilizing quantitative real-time RT-PCR we analyzed the expression of several genes, including IL-6, COX-2, MCP-1, IFN-γ, T-bet, IRF-1, Nox2, IL-33, and eotaxin-1 and revealed differential regulation between suture, sarcoidosis, and fungal granulomas. This is the first study demonstrating that quantification of target gene expression in FFPE tissue biopsies is a potentially effective diagnostic and research tool in sarcoidosis.     

脂蛋白相关磷脂酶A2与冠心病的相关性研究进展

脂蛋白相关磷脂酶A2（Lp-PLA2）是由炎性细胞产生并与低密度脂蛋白（LDL）结合,可水解氧化型低密度脂蛋白（ox-LDL）而产生炎症介质促进动脉粥样硬化。Lp-PLA2编码基因PLA2G7的单核苷酸多态性与冠心病之间存在明显相关性。Lp-PLA2作为新型的炎症标记物,与动脉粥样硬化的发生发展密切相关,作为冠心病的一个独立危险因素逐渐被关注,Lp-PLA2可能成为治疗冠心病的新靶点。本文就Lp-PLA2与冠心病的相关性研究新进展进行综述。     

聚乙烯亚胺非病毒基因载体结构修饰研究进展

聚乙烯亚胺（PEI）作为最经典的非病毒基因载体之一,由于其高转染效率,在基因递送领域受到极大的关注,但其毒性限制了聚乙烯亚胺的应用。本文综述了对聚乙烯亚胺进行不同的结构修饰,如多糖修饰、PEG修饰和低分子聚乙烯亚胺衍生物等,以实现在不显著降低转染效率的前提下减少细胞毒性。     

红藻氨酸受体与神经退行性变疾病相关性研究进展

研究表明,红藻氨酸受体（ KARs）在神经退行性变疾病中起着重要作用。兴奋性神经递质的过度活化KARs可引起该受体的过度表达,从而使神经细胞死亡。研究KARs的作用机制,可为临床治疗神经退行性变疾病提供治疗的靶点。