锻造成形有限元数值模拟技术

数值模拟是目前塑性成形分析最有效的方法.通过有限元数值模拟,可以预测金属流动规律,获得应力场、应变场及温度场等场量分布及变化,进而揭示出复杂的变形机理.介绍锻造成形有限元法以及模拟中的关键技术,并以基于DEFORM软件的热-力耦合模拟实验为例,探讨了数值模拟技术在工程实际中的指导意义.     

百万千瓦级核电站轴封型主泵整机集成试验验证优化方案研究

为确保主泵的安全性和可靠性,主泵整机在完成集成设计后需通过试验进行验证。文中介绍了主泵设计与验证的总体思路,提出了主泵工程样机需开展的整机试验项目。基于已有的试验条件,进行了主泵整机集成试验验证方案的优化和可行性分析。分析结果表明,在充分开展主泵各模块、子模块、部件和材料的试验与分析的基础上,可采用小流量试验方案进行主泵整机集成试验验证。     

盛事之后——走向可持续发展的奥运场馆建设

本文根据国外现代奥运场馆建设实例提出,面对近期直接目标和长远间接目标的矛盾,奥运场馆建设必须根据举办城市的发展具体情况,确定各种效益的优先关系,在城市整体长远规划基础上,从节约化、续用化、生态化三方面指导奥运建设,落实可持续发展原则。     

现代电弧炉的脱磷脱碳

对现代电弧炉炼钢中的脱磷、脱碳等问题进行研究,对影响脱磷、脱碳的几个主要因素:熔池温度、炉渣碱度、炉渣氧化性及渣量等进行讨论,并且分析了脱磷与脱碳的关系.     

板栗壳鞣质提取及其对DPPH自由基清除活性的研究

本研究以板栗加工的废弃物板栗壳为原材料,以期得到板栗壳中鞣质的最佳提取工艺,并对其抗氧化活性进行考察。通过分析比较筛选出了板栗壳鞣质提取最佳溶剂为乙醇,较优提取方法为回流法,并在此基础上实施了乙醇浓度、料液比和提取时间三个单因素实验和以此为依据的正交实验。结果表明,回流法提取板栗壳鞣质的最佳工艺条件为:25%乙醇为提取溶剂,提取时间为2 h,料液比为1∶10.5(g∶m L),在该条件下,板栗壳鞣质的提取量为14.617 mg/g;DPPH实验结果表明板栗壳鞣质粗提物具有较强的清除DPPH自由基的能力,可以作为一种天然抗氧化剂予以开发。      

杜香多糖的单糖组分分析及其理化性质研究

为分析杜香多糖的单糖组成、酶抑制作用及抗氧化性能,采用高效阴离子色谱法、PNPG法及ABTS法对杜香多糖样品进行了分析检测。检测得到杜香多糖含有鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖、半乳糖几种单糖组分;其对α-葡萄糖苷酶的抑制与浓度呈正相关,在3 mg/m L时,抑制率达30%;清除ABTS自由基的EC50为2.25 mg/m L。杜香多糖含有丰富的单糖组成,具有较好的α-葡萄糖苷酶抑制和体外抗氧化活性。      

The Effects of Exercise Training on Mitochondrial Function in Cardiovascular Diseases: A Systematic Review and Meta-Analysis

Mitochondria dysfunction is implicated in the pathogenesis of cardiovascular diseases (CVD). Exercise training is potentially an effective non-pharmacological strategy to restore mitochondrial health in CVD. However, how exercise modifies mitochondrial functionality is inconclusive. We conducted a systematic review using the PubMed; Scopus and Web of Science databases to investigate the effect of exercise training on mitochondrial function in CVD patients. Search terms included “mitochondria”, “exercise”, “aerobic capacity”, and “cardiovascular disease” in varied combination. The search yielded 821 records for abstract screening, of which 20 articles met the inclusion criteria. We summarized the effect of exercise training on mitochondrial morphology, biogenesis, dynamics, oxidative capacity, antioxidant capacity, and quality. Amongst these parameters, only oxidative capacity was suitable for a meta-analysis, which demonstrated a significant effect size of exercise in improving mitochondrial oxidative capacity in CVD patients (SMD = 4.78; CI = 2.99 to 6.57; p < 0.01), but with high heterogeneity among the studies (I² = 75%, p = 0.003). Notably, aerobic exercise enhanced succinate-involved oxidative phosphorylation. The majority of the results suggested that exercise improves morphology and biogenesis, whereas findings on dynamic, antioxidant capacity, and quality, were inadequate or inconclusive. A further randomized controlled trial is clearly required to explain how exercise modifies the pathway of mitochondrial quantity and quality in CVD patients.     

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS.     

Cordycepin Inhibits Growth and Metastasis Formation of MDA-MB-231 Xenografts in Nude Mice by Modulating the Hedgehog Pathway

We previously found that cordycepin inhibits the growth and metastasis formation of MDA-MB-231 cells through the Hedgehog pathway but has not validated this in vivo. In this study, we confirmed cordycepin’s anti-triple-negative breast cancer (TNBC) effect in nude mice and documented its mechanism. We found that cordycepin reduced the volume and weight of MDA-MB-231 xenografts and affected the expression of proliferation-, apoptosis-, epithelial–mesenchymal transition-, and matrix metalloproteinase-related proteins without side effects. RNA sequencing screening, pathway enrichment, and the protein network interaction analysis revealed enriched pathways and targets mainly concentrated on the Hedgehog pathway and its core components of SHH and GLI2. This indicates that the Hedgehog pathway plays a central role in the cordycepin-mediated regulation of growth and metastasis formation in TNBC. The database analysis of the Hedgehog pathway markers (SHH, PTCH1, SMO, GLI1, and GLI2) revealed that the Hedgehog pathway is activated in breast cancer tissues, and its high expression is not conducive to a patient’s survival. Finally, we verified that cordycepin effectively inhibited the Hedgehog pathway in TNBC through Western blotting and immunohistochemistry. This study found that cordycepin could regulate the growth and metastasis formation of TNBC through the Hedgehog pathway in vivo, which provides new insights for targeting and treating breast cancer.