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Expansion of TATB is studied on a molecular level by means of x‐ray crystallography. Continuous monitoring of the cell constants of TATB between 214 K and 377 K allows calculation of a volume change of +5.1% for this molecular system. Expansion of the pure material is almost exclusively a function of a 4% linear increase in the c axis (the perpendicular distance between sheets of hydrogen‐bonded TATB). Calculated from these data, the volume coefficient of thermal expansion for crystalline TATB is 30.4 × 10−5 K−1. The structural features of crystalline TATB and its anisotropic thermal‐expansion behaviour are compared with those of graphite and boron nitride. Two other crystalline products in the bulk TATB are either actual polymorphs of TATB or impurities.

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Blockchains are a topic of immense interest in academia and industry, but their true nature is often obscured by marketing and hype. In this tutorial, we explain the fundamental elements of blockchains. We discuss their ability to achieve availability, consistency, and data integrity as well as their inherent limitations. Using Ethereum as a case study, we describe the inner workings of blockchains in detail before comparing blockchains to traditional distributed systems. In the second part of our tutorial, we discuss the major challenges facing blockchains and summarize ongoing research and commercial offerings that seek to address these challenges. CCS Concepts: • General and reference → Surveys and overviews; • Computer systems organization → Peer-to-peer architectures; • Security and privacy → Cryptography; • Information systems → Data management systems;