The work presented herein focuses on simulating the compounding process via a torque rheometer, as well as the relationship between the melt viscosity and the polymer molecular weight (MW). We aim to predict the plasticization of polylactic acid (PLA) using polypropylene glycol (PPG) with different MWs. The rheological properties of the PLA/PPG composites containing PPG with different MWs were systematically studied by capillary rheometry and torque rheometry. The initial degradation of PLA/PPG composites during melt processing was monitored in real time. The results indicate that PPG can significantly reduce the melt viscosity of PLA/PPG composites, leading to obvious pseudoplastic fluid behavior. The lower the MW of PPG, the lower the viscosity of the PLA/PPG composite. The addition of PPG was favorable for the degradation of PLA during processing, and the degradation degree of the composite materials increased as the MW of PPG was decreased.
Subarachnoid hemorrhage (SAH) is an acute cerebral vascular disease featured by oxidative insults and neuroinflammation. Cycloastragenol (CAG), the major active component of Astragalus radix, has a wide range of biological functions. However, the potential beneficial effects and the underlying molecular mechanisms of CAG on SAH remain obscure. In the current study, the cerebroprotective effects and mechanism of CAG on SAH were evaluated both in vivo and in vitro. Our results indicated that CAG significantly suppressed SAH-triggered oxidative insults, inflammatory mediators production, microglia activation, and the neutrophil infiltration in the brain. In addition, CAG improved neurological function and ameliorated neuronal apoptosis and degeneration after SAH. In vitro results also revealed the therapeutic effects of CAG on neurons and microglia co-culture system. Mechanistically, CAG treatment upregulated sirtuin 1 (SIRT1) expression, inhibited the levels of FoxO1, nuclear factor-kappa B, and p53 acetylation, and suppressed the subsequent oxidative, inflammatory, and apoptotic pathways. In contrast, inhibiting SIRT1 by pretreatment with Ex527 abrogated the protective actions of CAG both in vivo and in vitro models of SAH. Collectively, our findings indicated that CAG could be a promising and effective drug candidate for SAH.
Injured bone regeneration requires complex and carefully orchestrated a series of events involving inflammation, angiogenesis, and osteogenesis. To mimic the developmental spatial structure, microenvironment of bone regeneration and the integration...
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