High-quality color image restoration from a disturbed graded-index imaging system by deep neural networks.

Imaging transmission plays an important role in endoscopic clinical diagnosis involved in modern medical treatment. However, image distortion due to various reasons has been a major obstacle to state-of-art endoscopic development. Here, as a preliminary study we demonstrate ultra-efficient recovery of exemplary 2D color images transmitted by a disturbed graded-index (GRIN) imaging system through the deep neural networks (DNNs). Indeed, the GRIN imaging system can preserve analog images through the GRIN waveguides with high quality, while the DNNs serve as an efficient tool for imaging distortion correction. Combining GRIN imaging systems and DNNs can greatly reduce the training process and achieve ideal imaging transmission. We consider imaging distortion under different realistic conditions and use both pix2pix and U-net type DNNs to restore the images, indicating the suitable network in each condition. This method can automatically cleanse the distorted images with superior robustness and accuracy, which can potentially be used in minimally invasive medical applications.

Design of reduced graphene oxide decorated with DOPO-phosphanomidate for enhanced fire safety of epoxy resin.

A facile approach was developed to simultaneously functionalize and reduce graphene oxide (GO) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-phosphonamidate. To achieve stable dispersion and effective stress transfer, graphene was functionalized by polyethyleneimine (PEI). To improve the fire resistance of bare graphene, DOPO was grafted on the surface of PEI-reduced graphene oxide (PEI-rGO) to obtain the grafting of DOPO-phosphonamidate on the graphene. A morphological study indicated that, due to the good interfacial interaction between the functionalized graphene and epoxy (EP), functionalized reduced graphene oxide (f-rGO) was well-dispersed in the host polymer. Incorporation of 3.0 wt% f-rGO led to the increased char yields of the EP. Moreover, the storage modulus and glass transition temperature were improved, respectively. The evaluation of combustion behavior demonstrated that the peak heat release rate and total heat release of f-rGO/EP were reduced by 31% and 34.3%, respectively, compared to those of neat EP. This dramatically reduced fire hazards were mainly attributed to the synergistic effect of f-RGO. On one hand, DOPO-phosphonamidate on the surface of GO promoted flame inhibition in the gas phase while protecting the rGO against fire. On the other hand, the adsorption and barrier effect of rGO inhibited the heat and gas release, respectively, promoting the formation of graphitized carbons.