As synthesised ZIF-8 nanoparticles (size $ 60 nm and specific surface area $ 1300-1600 m 2 g À1 ) were directly incorporated into a model polymer matrix (MatrimidÒ 5218) by solution mixing. This produces flexible transparent membranes with excellent dispersion of nanoparticles (up to loadings of 30 wt%) with good adhesion within the polymer matrix, as confirmed by scanning electron microscopy, dynamic mechanical thermal analysis and gas sorption studies. Pure gas (H 2 , CO 2 , O 2 , N 2 and CH 4 ) permeation tests showed enhanced permeability of the mixed matrix membrane with negligible losses in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that an increase in the free volume of the polymer with ZIF-8 loading together with the free diffusion of gas through the cages of ZIF-8 contributed to an increase in gas permeability of the composite membrane. The gas transport properties of the composite membranes were well predicted by a Maxwell model whilst the processing strategy reported can be extended to fabricate other polymer nanocomposite membranes intended for a wide range of emerging energy applications.
Matrix metalloproteinases (MMPs) are implicated in multiple sclerosis where one of their roles may be to facilitate the transmigration of circulating leukocytes into the CNS. Studies have focused on only a few MMPs, and much remains unknown of which of the 23 MMP family members is/are critical to the multiple sclerosis disease process. Using quantitative real time polymerase chain reactions, we have systematically analysed the expression of all 23 MMP members in subsets of leukocytes isolated from the blood of normal individuals. We found a distinctive pattern of MMP expression in different cellular populations: MMP-11, MMP-26 and MMP-27 were enriched in B cells, while MMP-15, MMP-16, MMP-24 and MMP-28 were prominent in T lymphocytes. Of interest is the enrichment of a majority of MMP members in monocytes: MMP-1, MMP-3, MMP-9, MMP-10, MMP-14, MMP-19 and MMP-25. MMP-2 and MMP-17 were also significantly represented in monocytes, although B cells had significant amounts of these MMPs. In correspondence with their strong expression of many MMP members, monocytes migrated more rapidly across a model of the blood-brain barrier in culture than T or B lymphocytes. Finally, we found higher levels of two of the monocyte-expressed MMPs in multiple sclerosis patients compared with normal individuals: MMP-2 and MMP-14. Tissue inhibitor of metalloproteinases (TIMP)-2 was also elevated in monocytes from multiple sclerosis patients, providing a mechanism for the reported activation of MMP-2 by MMP-14 and TIMP-2. These results emphasize that monocytes are prominent contributors of the neuroinflammation in multiple sclerosis through a mechanism that involves their high MMP expression and that they identify specific MMP members as targets for novel therapeutics in the disease.
The prognostic value of cardiopulmonary exercise tests in heart failure patients can be improved by assessing a new variable, the circulatory power - a surrogate of cardiac power - at peak exercise.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.