Janus Graphene Oxide Sponges for High-Purity Fast Separation of Both Water-in-Oil and Oil-in-Water Emulsions

Membrane separation of oil and water with high purity and high permeability is of great interest in environmental and industrial processes. However, membranes with fixed wettability can separate only one type of surfactant-stabilized emulsion (water-in-oil or oil-in-water). Here, we report on Janus graphene oxide (J-GO) sponges for high purity and high permeability separation of both water-in-oil and oil-in-water emulsions. Millimeter-scale reduced GO sponges with a controlled pore size (11.2 or 94.1 mu m) are synthesized by freeze drying, and the wettability is further controlled by fluorine (hydrophobic/oleophilic in air) or oxygen (hydrophilic/oleophilic in air) functionalization. J-GO sponges are prepared by the fluorine functionalization on one side and oxygen functionalization on the other side. Interestingly, the oil wettability of oxygen-functionalized surface turns into an oleophobic surface when immersed in water, which is explained by Young's theory. This effect is further used in the separation of both water-in-oil and oil-in-water emulsions by changing the flow direction. The purity of the separated oil and water is very high (>= 99.2%), and the permeability is more than an order of magnitude greater than those of the other Janus membranes reported. J-GO sponges can be reused with an excellent repeatability, demonstrating feasibility in practical applications. © 2017 American Chemical Society131

Towards a Universal Query Language for Resource Description Framework (RDF) and Topic Maps

ABSTRACT Resource Description Framework (RDF) and Topic Maps are the two prominent technologies of Semantic Web developed for the purpose to make Web useful for humans and 'understandable' by machines by facilitating knowledge integration and sharing. The basic goal of RDF and Topic Maps is the same, i.e. to successfully turn the vision of semantic web into reality by attaching rich structured semantics to web contents. The problem of interoperability between RDF and Topic Maps emerged due to the difference in their fundamental architectures and their owner organizations which may lead to islands on the future web. The architecture of RDF and Topic Maps is also complex and a suitable query language is the essential pats of it for the precise and quick retrieval of required information from RDF and Topic Maps. Therefore, several types of query languages have been developed for both technologies to retrieve the required information precisely from both RDF and Topic Maps. These query languages have the capability of logic and inferencing and may be used to address the problem of interoperability. The purpose of this paper is to thoroughly investigate all aspects of the available query languages developed for RDF and Topic Maps. In this paper, a comprehensive literature study and comparison of RDF and Topic Maps query languages has been done according to different parameters. It is concluded that a universal query language capable of retrieving and filtering both RDF and Topic Maps data is possible subjected to little more efforts. This paper will not only provide a jump start in the field for new comers but will also help future researchers in selecting one query language over the other for their applications

Highly elastic conductive sponges by joule heat-driven selective polymer reinforcement at reduced graphene oxide junctions

© 2019 Elsevier LtdPolymer reinforcement of reduced graphene oxide (rGO) sponges is widely employed to enhance mechanical strength and elasticity. However, the surplus polymer decreases electrical conductivity by passivating the conductive surface of rGO flakes. Here we firstly report the selective polydimethylsiloxane (PDMS) reinforcement at the flake junction of rGO sponge by the Joule heating process utilizing the high electrical contact resistance. The preferential Joule heating of the junction is theoretically simulated by finite element modeling and experimentally confirmed by micro-thermal infrared imaging. The local temperature increase results in the further reduction of rGO and preferential PDMS curing at the flake junction only. The PDMS/rGO mass ratio was carefully optimized at 3.96. The electrical conductivity (0.087 S m−1 at 0% strain) is more than an order of magnitude higher than that (0.00251 S m−1) of the conventional oven-heated sponge with a similar PDMS/rGO mass ratio. The mechanical strength is equivalent (210.3 kPa at 70% strain), in spite of the preferential polymer coating at the rGO flake junction only, with excellent elasticity. The Joule heating method is an excellent curing strategy to selectively reinforce flake junctions for conductive elastic rGO-polymer sponges11sciescopu