Graphical Abstract

Grand canonical Monte Carlo simulations were employed to investigate the adsorption and separation of C2H6, CO2 and CH4 on two zeolitic imidazolate frameworks (ZIF-2 and ZIF-71). The adsorption isotherm and isosteric heat of pure gas, the separation performance of C2H6-CH4, CO2-CH4 and C2H6-CO2 binary mixtures and C2H6-CO2-CH4 ternary mixtures on two ZIFs were simulated and discussed. For single component gas adsorption at a low pressure, the adsorption amount depended on isosteric heat; at a high pressure, due to the limited pore volume, ZIFs preferably adsorbed smaller size gas molecules. For gas mixture separation, energetic effect dominated at low pressure, therefore, ZIFs selectively adsorbed gas component with strong interactions; packing effect usually played an important role at high pressures, consequently, smaller size component would be more entropically favorable. Results demonstrated that both ZIF-2 and ZIF-71 were of good separation performance for these three binary mixtures. For the ternary mixture separation, it was found that ZIF-2 cowld effectively separate C2H6 and CO2 from CH4 at 3000-4000 kPa and room temperature.

Patch-based approaches to regenerating damaged myocardium include 3D bioprinting of heart patches for epicardial transplantation. By the time this is ready for widespread clinical use, it will be important that patches can be delivered via minimally invasive and robotic surgical approaches. Here, we aimed to design a minimally invasive patch transplantation surgical device for human operation as well as master-slave and fully automated robotic control. METHOD: Over a 12-month period (2019-20) in our multidisciplinary team we designed a surgical instrument to transplant 3D bioprinted heart patches to the epicardial surface. The device was designed for use via uni-portal or multi-portal Video-Assisted Thorascopic Surgery (VATS). Forpreliminary feasibility and sizing, we used a 3D printer to produce a flexible resin model from a computer-aided design (CAD) software platform in preparation for more robust high-resolution metal manufacturing. RESULTS: The instrument was designed as a sheath containing foldable arms, less than 2 cm in diameter when infolded to fit minimally invasive thoracic ports. The total length was 35 cm. When the arms were projected from the sheath, three moveable mechanical arms at the distal end were designed to hold the 3D bioprinted patch. A rotational head allowing for the arms to be angled in real time, a surface with micro-attachment points for patches and a releasing mechanism to release the patch was included. At the proximal end, right-angled handles corresponding to each distal arm could be used to control the distal arms, either manually, or by robotic hardware attached to the arms. CONCLUSION: This world-first design paves the way for a new approach for epicardial patch transplantation via minimally invasive robotic surgery. Full prototyping, proof-of-concept and efficacy trials will be needed to confirm the utility of this approach for translation from bench to bedside.