Polyimides with excellent physicochemical properties have aroused a great deal of interest as gas separation membranes; however, the severe performance decay due to CO2-induced plasticization remains a challenge. Fortunately, in recent years, advanced plasticization-resistant membranes of great commercial and environmental relevance have been developed. In this review, we investigate the mechanism of plasticization due to CO2 permeation, introduce effective methods to suppress CO2-induced plasticization, propose evaluation criteria to assess the reduced plasticization performance, and clarify typical methods used for designing anti-plasticization membranes.
In recent years, investigations on various forms of solution for Internet of Things (IoT) paradigm opens the new era of smart devices. The Information-Centric Internet of Things (IC-IoT) can apply the characteristics of content caching which is a typical feature of Information-Centric Networking. Therefore, designing an efficient caching strategy for IC-IoT is able to improve the efficiency of smart devices. In this paper, we propose a Pre-Caching Strategy based on the Relevance of smart device request Content, namely PCSRC. After the first request of content chunk at a smart device side, PCSRC pre-caches the rest of the content chunks. There are two types of cached content chunks, that is, actual requested content chunks and pre-caching content chunks. Actual requested content chunks are pushed forward hop-by-hop according to the trend of the local activity. The popular content will be gradually pushed to the edge of IC-IoT. Furthermore, a sojourn time of a cached content chunk is employed to save storage space. The simulation results show PCSRC can reach 42.7% on the cache hit ratio with the different storage sizes. For the average hop count, PCSRC can increase about 42.2% than that of ProbCache. And PCSRC can improve about 47.9% than that of CEE for the average hop count.INDEX TERMS Information-centric networking, Internet of Things, content chunk, local activity, pre-caching.
Exosomal MicroRNA-21 (miRNA-21, miR-21) is significantly up-regulated in blood samples of patients with lung cancer. Exosomal-derived miR-21 can be used as a promising biomarker for the early diagnosis of lung cancer. This paper develops a fluorescent biosensor based on the combination of magnetic nanoparticles (MNPs), cascade strand displacement reaction (CSDR) and CRISPR/Cas12a to detect the exosomal miR-21 from lung cancer. The powerful separation performance of MNPs can eliminate the potential interference of matrix and reduce the background signal, which is very beneficial for the improvement of specificity and sensitivity. The CSDR can specifically transform one miR-21 into plenty of DNA which can specifically trigger the trans-cleavage nuclease activity of Cas12a, resulting in the cleavage of ssDNA bi-labeled with fluorescent and a quencher. Under the optimized experimental conditions, the developed fluorescence biosensor exhibited high sensitivity and specificity towards the determination of exosomal-derived miR-21 with a linear range from 10 to 1 × 105 fM and a low detection limit of about 0.89 fM. Most importantly, this method can be successfully applied to distinguish the exosomal miR-21 from the lung cancer patients and the healthy people.
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