Study of alpha-, beta- and gamma-cyclodextrin/C-60 supramolecular complexes: Influence of the cavity dimension toward the host-guest complexes

Herein we report the spectroscopic, electrochemical, TEM and DLS characterizations Of C-60 supramolecular inclusion complexes with alpha-, beta- and gamma-cyclodextrins prepared using anionic C-60. The results indicate that the cyclodextrin itself has little effect on the encapsulated C-60 or on the properties of the inclusion complex. Instead, the cyclodextrin has a significant influence on the aggregation behavior of individual complex in aqueous solution, which in turn affects the property of the supramolecular complex of cyclodextrin and C-60 greatly, As the cavity dimension of cyclodextrin becomes smaller as it changes from gamma-CD to beta-CD, and finally to alpha-CD, it is observed that more aggregation occurs for the corresponding inclusion complex in aqueous solution.

A new flow field and its two-dimension model for polymer electrolyte membrane fuel cells (PEMFCs)

A new flow field was designed to search flow fields fitting polymer electrolyte membrane fuel cells (PEMFCs) better due its extensible. There are many independent inlets and outlets in the new flow field. The new flow field we named NINO can extend to be more general when pressures at the inlet and outlet vary and some usual flow fields will be obtained. A new mathematical model whose view angle is obverse is used to describe the flow field.

Factors affecting pore structure and performance of poly(vinylidene fluoride-co-hexafluoro propylene) asymmetric porous membrane

Preparation of poly(vinylidene fluoride-co-hexafluoro propylene) (F2.6) flat-sheet asymmetric porous membrane has been studied for the first time. Factors affecting F2.6 membrane pore structure and permeate performance, such as macromolecule pore formers (polyethylene glycol-400, 1000, 1540, 2000 and 6000), the small molecule former (glycerol), swelling agent (trimethyl phosphate) in casting solution, precipitating bath component and temperature, exposure time and ambient humidity, were investigated in detail. Average pore radius and porosity were used to characterize F2.6 membrane structure, and respectively, determined by ultrafiltration and gravimetric method for the wet membrane. Morphology of the resultant membranes was observed by scanning electronic microscopy (SEM). Final test on permeate performance of F2.6 porous membrane was carried out by a direct contact membrane distillation (DCMD) setup. The experimental F2.6 membrane exhibits a higher distilled flux than PVDF membrane under the same operational situations. The determination of contact angle to distilled water also reveals higher hydrophobic nature than that of PVDF membrane.