Deep learning for synthetic microstructure generation in a materials-by-design framework for heterogeneous energetic materials

The sensitivity of heterogeneous energetic (HE) materials (propellants, explosives, and pyrotechnics) is critically dependent on their microstructure. Initiation of chemical reactions occurs at hot spots due to energy localization at sites of porosities and other defects. Emerging multi-scale predictive models of HE response to loads account for the physics at the meso-scale, i.e. at the scale of statistically representative clusters of particles and other features in the microstructure. Meso-scale physics is infused in machine-learned closure models informed by resolved meso-scale simulations. Since microstructures are stochastic, ensembles of meso-scale simulations are required to quantify hot spot ignition and growth and to develop models for microstructure-dependent energy deposition rates. We propose utilizing generative adversarial networks (GAN) to spawn ensembles of synthetic heterogeneous energetic material microstructures. The method generates qualitatively and quantitatively realistic microstructures by learning from images of HE microstructures. We show that the proposed GAN method also permits the generation of new morphologies, where the porosity distribution can be controlled and spatially manipulated. Such control paves the way for the design of novel microstructures to engineer HE materials for targeted performance in a materials-by-design framework

Multiple Endocrine Neoplasia Type 1 with Multiple Leiomyomas Linked to a Novel Mutation in the MEN1 Gene

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited syndrome. MEN1 is characterized by the presence of functioning and nonfunctioning tumors or hyperplasia of the pituitary gland, parathyroid glands, and pancreatic islet cells. In addition, MEN1 carriers can have adrenal or thyroid tumors and non-endocrine tumors, such as lipomas, angiofibromas, and leiomyomas. Although leiomyoma is not a major component of MEN1, it is thought to occur more frequently than expected. However, there has been no report of a case of MEN1 with leiomyoma in Korea so far. This report describes a patient with multiple leiomyomas in MEN1. A 50-year-old woman was referred for further evaluation of elevated calcium levels and osteoporosis. Biochemical abnormalities included hypercalcemia with elevated parathyroid hormone. There was hyperprolactinemia with pituitary microadenoma in sella MRI. An abdominal MRI demonstrated adrenal nodules and leiomyomas in the bladder and uterus. Endoscopic ultrasonography demonstrated esophageal leiomyoma and pancreatic islet cell tumor. A subtotal parathyroidectomy with thymectomy was performed. Sequencing of the MEN1 gene in this patient revealed a novel missense mutation (D350V, exon 7). This is the first case of MEN1 accompanied with multiple leiomyomas, parathyroid adenoma, pituitary adenoma, pancreatic tumor, and adrenal tumor

Metastable hexagonal close-packed palladium hydride in liquid cell TEM

Metastable phases-kinetically favoured structures-are ubiquitous in nature1,2. Rather than forming thermodynamically stable ground-state structures, crystals grown from high-energy precursors often initially adopt metastable structures depending on the initial conditions, such as temperature, pressure or crystal size1,3,4. As the crystals grow further, they typically undergo a series of transformations from metastable phases to lower-energy and ultimately energetically stable phases1,3,4. Metastable phases sometimes exhibit superior physicochemical properties and, hence, the discovery and synthesis of new metastable phases are promising avenues for innovations in materials science1,5. However, the search for metastable materials has mainly been heuristic, performed on the basis of experiences, intuition or even speculative predictions, namely 'rules of thumb'. This limitation necessitates the advent of a new paradigm to discover new metastable phases based on rational design. Such a design rule is embodied in the discovery of a metastable hexagonal close-packed (hcp) palladium hydride (PdHx) synthesized in a liquid cell transmission electron microscope. The metastable hcp structure is stabilized through a unique interplay between the precursor concentrations in the solution: a sufficient supply of hydrogen (H) favours the hcp structure on the subnanometre scale, and an insufficient supply of Pd inhibits further growth and subsequent transition towards the thermodynamically stable face-centred cubic structure. These findings provide thermodynamic insights into metastability engineering strategies that can be deployed to discover new metastable phases. © 2022. The Author(s), under exclusive licence to Springer Nature Limited.11Nsciescopu