单向拉伸条件下补片参数对复合材料胶接修复结构的影响

建立含中心半穿透圆孔的损伤金属板修补结构的三维有限元模型,以应力集中系数(Stress Concentration Factor,SCF)和挠度w作为复合材料胶接修复效果的指标,分析单向拉伸条件下,正方形补片的长度、厚度和铺层方式对修复效果的影响。结果表明:补片长度取孔直径的3.5倍、厚度取孔深度的0.6~0.8倍、铺层方式取0°/90°铺层时,复合材料单面修复含损伤裂纹板的效果较好。根据分析结果制备了实验件,进行了单向静拉伸实验,修补实验件的破坏强度比未修补实验件提高了10.1%。     

爆炸荷载下缺陷介质裂纹扩展规律数值分析研究

利用爆炸加载数字激光动态焦散线试验系统,同时借助ABAQUS有限元分析中内聚力模型数值计算方法,研究了爆炸应力波作用下缺陷介质裂纹扩展规律,并将试验结果与数值计算结果进行了对比。研究表明:在爆炸应力波作用下预制缺陷两端产生了两条翼裂纹A、B,扩展长度基本相同,方向垂直于预制缺陷。两条翼裂纹的扩展基本是对称的,只是在尾端发生轻微翘曲;翼裂纹扩展速度先增大至峰值又振荡减小,之后又增大至第二个较小的峰值,然后又减小,这种变化趋势和裂纹尖端应力强度因子KⅠ保持一致;扩展角β为85°时,计算结果较为接近试验,内聚力模型为动态裂纹扩展的研究提供了一种有效的方法。     

材料疲劳与断裂试验中的若干问题(2)

材料疲劳与断裂试验结果是否准确有效通常受多种因素的影响。从试验原始数据的不同处理方法和试验环境两个方面分析讨论其对材料疲劳与断裂性能试验处理结果的影响,为获得准确可靠的试验数据及其在工程设计及可靠性服役评估等方面提供支持。     

镍基单晶高温合金涡轮叶片缘板杂晶的研究进展

镍基单晶高温合金涡轮叶片缘板杂晶的出现严重影响叶片的力学性能,导致叶片报废。综述了关于缘板杂晶的形成本质的研究,总结了不同影响因素对缘板杂晶形成的影响及原因并概况了几种不同杂晶的控制方法,指出了以往研究中存在的问题,展望了未来研究的方向。     

Silver nanoparticles reduce the apoptosis induced by tumor necrosis factor-α

Silver nanoparticles (AgNPs) are widely known to have anti-inflammatory properties, but the exact mechanism underlying this anti-inflammatory effect is not clearly understood. Tumor necrosis factor-α (TNFα) is a major pro-inflammatory cytokine that is expressed in the early stage of cell inflammation and induces apoptosis by several known pathways. Our study aimed to investigate the effect of AgNPs on the response of lung epithelial cells to TNFα and the molecular mechanism of this response. Lung epithelial cell line NCI-H292 cells were exposed to AgNPs (5 µg/mL) and/or TNFα (20 ng/mL) for 24 h, then cellular uptake was analyzed using flow cytometry. Our results showed that AgNPs were taken up by cells in a dose-dependent manner and that the cellular uptake ratio of AgNPs was significantly increased in the presence of TNFα. Apoptosis assays indicated that exposure to AgNPs significantly decreased the apoptotic effect of TNFα. Confocal microscopy was used to localize the tumor necrosis factor receptor 1 (TNFR1) and revealed that TNFR1 localized on the surface of cells exposed to TNFα. In contrast, TNFR1 localized inside cells exposed to both AgNPs and TNFα, with very few receptors scattered on the cell membrane. The results indicated that AgNPs reduced the cell surface TNFR1 expression level. The results suggested that the reduction of surface TNFR1 reduced cellular response to TNFα, resulting in an anti-apoptotic effect.     

Immobilization of Photo‐Immunoconjugates on Nanoparticles Leads to Enhanced Light‐Activated Biological Effects

The past three decades have witnessed notable advances in establishing photosensitizer–antibody photo‐immunoconjugates for photo‐immunotherapy and imaging of tumors. Photo‐immunotherapy minimizes damage to surrounding healthy tissue when using a cancer‐selective photo‐immunoconjugate, but requires a threshold intracellular photosensitizer concentration to be effective. Delivery of immunoconjugates to the target cells is often hindered by I) the low photosensitizer‐to‐antibody ratio of photo‐immunoconjugates and II) the limited amount of target molecule presented on the cell surface. Here, a nanoengineering approach is introduced to overcome these obstacles and improve the effectiveness of photo‐immunotherapy and imaging. Click chemistry coupling of benzoporphyrin derivative (BPD)–Cetuximab photo‐immunoconjugates onto FKR560 dye‐containing poly(lactic‐co‐glycolic acid) nanoparticles markedly enhances intracellular photo‐immunoconjugate accumulation and potentiates light‐activated photo‐immunotoxicity in ovarian cancer and glioblastoma. It is further demonstrated that co‐delivery and light activation of BPD and FKR560 allow longitudinal fluorescence tracking of photoimmunoconjugate and nanoparticle in cells. Using xenograft mouse models of epithelial ovarian cancer, intravenous injection of photo‐immunoconjugated nanoparticles doubles intratumoral accumulation of photo‐immunoconjugates, resulting in an enhanced photoimmunotherapy‐mediated tumor volume reduction, compared to “standard” immunoconjugates. This generalizable “carrier effect” phenomenon is attributed to the successful incorporation of photo‐immunoconjugates onto a nanoplatform, which modulates immunoconjugate delivery and improves treatment outcomes.     

Spatial Micropatterning of Growth Factors in 3D Hydrogels for Location‐Specific Regulation of Cellular Behaviors

Growth factors are potent stimuli for regulating cell function in tissue engineering strategies, but spatially patterning their presentation in 3D in a facile manner using a single material is challenging. Micropatterning is an attractive tool to modulate the cellular microenvironment with various biochemical and physical cues and study their effects on stem cell behaviors. Implementing heparin's ability to immobilize growth factors, dual‐crosslinkable alginate hydrogels are micropatterned in 3D with photocrosslinkable heparin substrates with various geometries and micropattern sizes, and their capability to establish 3D micropatterns of growth factors within the hydrogels is confirmed. This 3D micropatterning method could be applied to various heparin binding growth factors, such as fibroblast growth factor‐2, vascular endothelial growth factor, transforming growth factor‐betas and bone morphogenetic proteins while retaining the hydrogel's natural degradability and cytocompability. Stem cells encapsulated within these micropatterned hydrogels have exhibited spatially localized growth and differentiation responses corresponding to various growth factor patterns, demonstrating the versatility of the approach in controlling stem cell behavior for tissue engineering and regenerative medicine applications.     

Laser‐Assisted Large‐Scale Fabrication of All‐Solid‐State Asymmetrical Micro‐Supercapacitor Array

The micro‐supercapacitors are of great value for portable, flexible, and integrated electronic equipments. Here, the large‐scale and integrated asymmetrical micro‐supercapacitor (AMSC) array is fabricated in virtue of the laser direct writing and electrodeposition technology. The AMSC shows the ideal flexibility, high areal specific capacitance (21.8 mF cm^?2), and good rate capability. Moreover, its energy density reaches 12.16 µW h cm^?2, outperforming most micro‐supercapacitors reported previously. Meanwhile, large‐scale series‐connected AMSCs are integrated on the flexible substrates (e.g., indium tin oxide‐polyethylene terephthalate film), which can power a veriety of the commercial electronics. The combination of AMSCs array, solar cell, and electronic device proves the feasibility for practical application in the portable, flexible, and integrated electronic equipments.