ABSTRACT
Widespread access to greener energy is required in order to mitigate the effects of climate change. A significant barrier to cleaner natural gas usage lies in the safety/efficiency limitations of storage technology. Despite highly porous metal-organic frameworks (MOFs) demonstrating record-breaking gas-storage capacities, their conventionally powdered morphology renders them non-viable. Traditional powder shaping utilising high pressure or chemical binders collapses porosity or creates low-density structures with reduced volumetric adsorption capacity. Here, we report the engineering of one of the most stable MOFs, Zr-UiO-66, without applying pressure or binders. The process yields centimetre-sized monoliths, displaying high microporosity and bulk density. We report the inclusion of variable, narrow mesopore volumes to the monoliths' macrostructure and use this to optimise the pore-size distribution for gas uptake. The optimised mixed meso/microporous monoliths demonstrate Type II adsorption isotherms to achieve benchmark volumetric working capacities for methane and carbon dioxide. This represents a critical advance in the design of air-stable, conformed MOFs for commercial gas storage.
ABSTRACT
Two new bismuth metal-organic frameworks (Bi-MOFs) were discovered using high throughput experiments employing bismuth(iii) nitrate pentahydrate and triazine-2,4,6-triyl-tribenzoic acid (H3TATB). The reaction was carried out for long reaction times (â¼5 d) in a water/DMF-mixture and resulted in the formation of [Bi2(O)(OH)(TATB)]·H2O (denoted as CAU-35). By switching to short reaction times and a methanol/DMF-mixture as the solvent, an analogue of CAU-7-BTB with the composition [Bi(TATB)]·DMF·6H2O (denoted as CAU-7-TATB) was obtained. The use of the amino-functionalised H3TATB linker (H3TATB-NH2) resulted in the formation of a functionalised porous Bi-MOF with the composition [Bi(TATB-NH2)]·5H2O·0.5DMF (CAU-7-TATB-NH2). The structures of CAU-35 and CAU-7-TATB were successfully solved and refined from the PXRD data. CAU-7-TATB-NH2 was post-synthetically modified using anhydrides (acetic anhydride and valeric anhydride), cyclic anhydrides (succinic anhydride and phthalic anhydride), and 1,3-propane sultone. The degree of conversion ranged from 33% to 79%.
Subject(s)
Bone Development , Growth Plate/anatomy & histology , Rabbits/anatomy & histology , Animals , MaleABSTRACT
Twenty-nine patients with transposition of the great arteries (TGA) and intact ventricular septum underwent hemodynamic and angiocardiographic investigation 18,8 +/- 5,8 months after inflow correction (Mustard). The mean age at operation was 14,6 +/- 7,5 months and in all, a good anatomical result was achieved. The hemodynamic parameters such as cardiac index, pressures in all heart chambers as well as in the venous channels and arterial vessels were found within normal limits. The end-diastolic volume of the right ventricle (RVEDV) was closely correlated to body surface area (r = 0,697). It increased, however, more rapidly than in children with normal hearts. Mean RVEDV/m2 was 86 +/- 8 ml which is 123 +/- 10% of the normal values for children (70 +/- 13 ml) according to Graham et al. The mean ejection fraction (EF) of the right ventricle (58 +/- 7%) was only slightly below the normal range (65 +/- 7%). Thus, a good hemodynamic function of the RV can be assumed at least for the early postoperative years after a Mustard operation. It remains open, however, if the more rapid increase of RVEDV/m2 expresses the RV adjustment to the afterload of the systemic circulation or if this should be interpreted as an early sign of RV functional impairment.
