Hybrid materials for molecular sieves

Hybrid microporous organosilica membranes for molecular separations made by acid-catalyzed solgel synthesis from bridged silsesquioxane precursors have demonstrated good performance in terms of flux and selectivity and remarkable hydrothermal stability in various pervaporation and gas separation processes. The availability of wide range of α,ω-bis(trialkoxysilyl)alkane and 1,4-bis (triethoxysilyl)benzene precursors allows tuning of membrane properties such as pore size and chemistry. This chapter presents an overview of the synthesis and application of hybrid organosilica microporous membranes in liquid and gas separation processes. After a concise discussion of the history of solgel-derived microporous ceramic membranes for molecular separations, the solgel chemistry of bridged silsesquioxanes and all relevant processing steps needed to obtain a supported microporous films suitable for molecular separations are discussed. The performance of these membranes is correlated with the membrane compositional properties, such as nature, stiffness and length of the bridging group, and details of the solgel process

Limitations to the performance of PIT Tl(Bi)-1223 tapes.

We have investigated the possibility of improving the weak link properties of Tl-1223 tape by melt processing, and also studied the technical limitations of coil fabrication using multimeter lengths of PIT tape. We conclude that melt processing does offer some potential for grain growth, but that grain alignment is only achieved in some places at the Ag/1223 interface. Until we can establish more control of the local grain alignment by altering the geometry of the samples, the properties of coils in high fields remains rather poor

Use of partial melting in Tl-1223 coil production

We report progress towards defining the optimum conditions for melt processing TlBi-1223 PIT tapes. The Bi substitution level has been found to have a strong influence on these conditions, affect the intercalation structure of the 1223 phase and the amount of secondary phases observed. TEM studies have identified a new Ba-Sr-Bi-Ca-O phase with a layered structure. A 3 pancake coil of length greater than 10m has been fabricated and tested in high magnetic fields. We conclude that although melt processing can be used to significantly modify the grain structure, further work on grain alignment is required to achieve useful properties

Past, present and future of dynamic kidney and liver preservation and resuscitation.

The increased demand for organs has led to the increased usage of “higher-risk” kidney and liver grafts. These grafts from donation after circulatory death or expanded criteria donors are more susceptible to preservation injury and have a higher risk of unfavourable outcomes. Dynamic, instead of static preservation could allow for organ optimisation, offering a platform for viability assessment, active organ repair and resuscitation. Ex situ machine perfusion and in situ regional perfusion in the donor are emerging as potential tools to preserve and resuscitate vulnerable grafts. Preclinical findings have ignited clinical organ preservation research that investigates dynamic preservation, its various modes (continuous, pre-implantation) and temperatures (hypothermic, sub-, or normothermic). This review outlines the current status of dynamic preservation of kidney and liver grafts and describes on-going research and emerging clinical trial