The present study focused on the action mechanism of S. pneumoniae (Sp) in inducing autophagy in human alveolar epithelial cells. Sp, a gram-positive extracellular bacterium, activates autophagy with considerably increased microtuble-associated protein light chain 3 (LC3) punctation in A549 cells. The accumulation of typical autophagosomes and conjugation of LC3 to phosphatidylethanolamine were observed in Sp-infected cells as an indication of autophagy. Using the pneumolysin (PLY) mutant, we successfully demonstrated that PLY is involved in initiating autophagy without affecting the expression levels of PI3K-III and Beclin1. PLY-mediated autophagy depends on the inhibition of the phosphoinositide 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway. Furthermore, Sp could also lead to the reactive oxygen species (ROS) hypergeneration in A549 cells. Taken together, Sp infection-induced autophagy is PLY-mediated through ROS hypergeneration and mTOR inhibition. PI3K-I and rapamycin (autophagy inducers) enhanced bacterial clearance, whereas wortmannin (autophagy inhibitor) and acetylcysteine (ROS inhibitor) reduced intracellular bacteria clearance. Thus, Sp-induced autophagy represents a host-protective mechanism, providing new insight into the pathogenesis of respiratory tract Sp infection.
In order to improve the modernization of textile production, single off-line testing will miss a lot of information of work-field. It is necessary to improve the yarn quality testing methods to make it more perfect. So the production will grow toward the rapid, high yield, high-quality. In this study, only a sensor that is Intelligent laser sensor is used to finish the yarn quality on line testing. Experimental device is easy to install and carry. It can print images and data at all times. The accurate information of equipment state and yarn can be got from the experimental curve and the trend figure, which improved the inspection efficiency and accuracy of yarn quality.
Aviation polysulfide sealants have been subjected to thermo-oxidative ageing. Their morphologies, Shore A hardness, and tensile properties have been tested by means of an optical microscope, a glossiness meter, a Shore A hardness meter, and a universal testing machine. Changes in their microstructures were measured by Fourier-transform infrared spectroscopy and dynamic mechanical analysis (DMA). The results showed that glossiness was gradually reduced, and bubbles appeared on the surface of the samples during the course of ageing. The Shore A hardness of the sealant first decreased and then remained unchanged. Likewise, the tensile strength and tensile elongation percent first decreased and then remained unchanged. The infrared monitoring showed that the sealant underwent a post-cure reaction. The glass transition temperature and the room-temperature storage modulus of the sealant remained unchanged. No new functional groups were formed during ageing of the sealant. The aviation sealants did not undergo chemical degradation, showing that they have good endurance under thermo-oxidative conditions.
Low-density polyethylene (LDPE) film was treated by low-temperature plasma. Scanning electronic microscope, electronic universal testing machine, contact angle/interfacial tension measuring instrument were used to analyze the surface morphology, surface contact angle, bonding strength and performance of LDPE film before and after they were treated by low-temperature plasma. The results show that air ambience is more appropriate than N2, CO2 for treatment. Specifically, plasma treatment in air ambience, under conditions of 44 W (power), 30 s (duration) and 60 Pa (vacuum degree), can decline static contact angle of LDPE film from 101° to 13.5°. The transiency of plasma-treated LDPE film is so obvious that storage time of longer than one hour will result in a contact angle up to 74° and loss of plasma treatment effect (timeliness). Therefore, the reversible plasma-treated LDPE film should be processed immediately.
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