Yingshihan Zhu

© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.Metal-organic frameworks are crystalline porous materials with designable topology, porosity and functionality, having promising applications in gas storage and separation, ion conduction and catalysis. It is challenging to observe MOFs with transmission electron microscopy due to the extreme instability of MOFs upon electron beam irradiation. Here, we use a direct-detection electron-counting camera to acquire TEM images of the MOF ZIF-8 with an ultralow dose of 4.1 electrons per square ångström to retain the structural integrity. The obtained image involves structural information transferred up to 2.1 Å, allowing the resolution of individual atomic columns of Zn and organic linkers in the framework. Furthermore, TEM reveals important local structural features of ZIF-8 crystals that cannot be identified by diffraction techniques, including armchair-type surface terminations and coherent interfaces between assembled crystals. These observations allow us to understand how ZIF-8 crystals self-assemble and the subsequent influence of interfacial cavities on mass transport of guest molecules.

What does it mean to be a good ally to the LGBTQ community? Does it count if you attach a rainbow pin to your backpack or post occasional messages of support on social media? We argue that in order to be a good ally involves avoiding the vice of complacency and that allies need to ask themselves two distinct, but related questions: (1) Who are you an ally to?; (2) How are you an ally? While reflecting on these questions helps allies examine what they have or have not been doing so far, these questions point towards future action by encouraging allies to consider what else they need to be doing to help and who else they need to help.