Accelerating Solvent Selection for Type II Porous Liquids.

Type II porous liquids, comprising intrinsically porous molecules dissolved in a liquid solvent, potentially combine the adsorption properties of porous adsorbents with the handling advantages of liquids. Previously, discovery of appropriate solvents to make porous liquids had been limited to direct experimental tests. We demonstrate an efficient screening approach for this task that uses COSMO-RS calculations, predictions of solvent pKa values from a machine-learning model, and several other features and apply this approach to select solvents from a library of more than 11,000 compounds. This method is shown to give qualitative agreement with experimental observations for two molecular cages, CC13 and TG-TFB-CHEDA, identifying solvents with higher solubility for these molecules than had previously been known. Ultimately, the algorithm streamlines the downselection of suitable solvents for porous organic cages to enable more rapid discovery of Type II porous liquids.

A prospect of cost-effective handling and transportation of graphene oxides: folding and redispersion of graphene oxide microsheets.

Controlling the assembly of 2D materials such as graphene oxides (GO) has a significant impact on their properties and performance. One of the critical issues on the processing and handling of GO is that they need to be in dilution solution (0.5 to 2.5 wt%) to maintain their high degree of exfoliation and dispersion. As a result, the shipment of GO in large quantity involves a huge volume of solvent (water) and thus the transportation costs for large sales volume would become extremely high. Through cross-sectional scanning electron microscopy and polarized optical microscopy together with x-ray diffraction and small-angle x-ray scattering studies, we demonstrated that the assembly and structure of GO microsheets can be preserved without restacking, when assembled GO via water-based wet spinning are re-dispersed into solution. A couple of alkyl ammonium bromides, CTAB and TBAB, as well as NaOH, were examined as coagulants and the resulting fibers were redispersed in an aqueous solution. The redispersed solution of fibers that were wet-spun into the commonly used CTAB and TBAB coagulation baths, maintained their physico-chemical properties (similar to the original GO dispersion) however, did not reveal preservation of liquid crystallinity. Meanwhile, the redispersed fibers that were initially spun into NaOH coagulation bath were able to maintain their liquid crystallinity if the lateral size of the GO sheets was large. Based on these findings, a cost-effective solid handling approach is devised which involves (i) processing GO microsheets in solution into folded layers in solid-state, (ii) transporting assembled GO to the customers, and (iii) redispersion of folded GO into a solution for their use. The proposed solid handling of GO followed by redispersion into solution can greatly reduce the transportation costs of graphene oxide materials by reducing the transportation volume by more than 90%.

A novel software-defined network packet security tunnel forwarding mechanism.

The OpenFlow protocol match field capacity is fixed and limited, and packet forwarding in software-defined network lacks valid authentication of data source, integrity verification, and confidentiality protection mechanism. OpenFlow only supports the MPLS label tunnel establishment, and therefore cannot establish a secure tunnel flexibly. In order to solve these problems, we propose P4Sec, a novel software-defined network packet security tunnel forwarding mechanism. As P4 allows the data plane to be reprogrammed to realize the characteristics of packet forwarding, we build a software-defined network security tunnel to prevent data malicious tampering, stealing, forgery and other malicious network behavior, implementing packet routing and forwarding based on gateway identity. Finally, we construct a P4Sec prototype system based on the software switch BMv2, verify the effectiveness of the mechanism through experimental analysis, and evaluate the overhead of the mechanism. The results demonstrate that P4Sec security mechanism ensure the authenticity, integrity, and confidentiality of forwarded data, and realize the secure forwarding requirements of data packets in software-defined network.