Inorganic Materials Synthesis Planning with Literature-Trained Neural Networks

Leveraging new data sources is a key step in accelerating the pace of materials design and discovery. To complement the strides in synthesis planning driven by historical, experimental, and computed data, we present an automated method for connecting scientific literature to synthesis insights. Starting from natural language text, we apply word embeddings from language models, which are fed into a named entity recognition model, upon which a conditional variational autoencoder is trained to generate syntheses for arbitrary materials. We show the potential of this technique by predicting precursors for two perovskite materials, using only training data published over a decade prior to their first reported syntheses. We demonstrate that the model learns representations of materials corresponding to synthesis-related properties, and that the model's behavior complements existing thermodynamic knowledge. Finally, we apply the model to perform synthesizability screening for proposed novel perovskite compounds.Comment: Added new funding support to the acknowledgments section in this versio

Left ventricular global longitudinal strain in bicupsid aortic valve patients: head-to-head comparison between computed tomography, 4D flow cardiovascular magnetic resonance and speckle-tracking echocardiography

Left ventricular global longitudinal strain (LVGLS) analysis is a sensitive measurement of myocardial deformation most often done using speckle-tracking transthoracic echocardiography (TTE). We propose a novel approach to measure LVGLS using feature-tracking software on the magnitude dataset of 4D flow cardiovascular magnetic resonance (CMR) and compare it to dynamic computed tomography (CT) and speckle tracking TTE derived measurements. In this prospective cohort study 59 consecutive adult patients with a bicuspid aortic valve (BAV) were included. The study protocol consisted of TTE, CT, and CMR on the same day. Image analysis was done using dedicated feature-tracking (4D flow CMR and CT) and speckle-tracking (TTE) software, on apical 2-, 3-, and 4-chamber long-axis multiplanar reconstructions (4D flow CMR and CT) or standard apical 2-, 3-, and 4-chamber acquisitions (TTE). CMR and CT GLS analysis was feasible in all patients. Good correlations were observed for GLS measured by CMR (− 21 ± 3%) and CT (− 20 ± 3%) versus TTE (− 20 ± 3%, Pearson’s r: 0.67 and 0.65, p 0.61, p < 0.001). Feature-tracking GLS analysis is feasible using the magnitude images acquired with 4D flow CMR. GLS measurement by CMR correlates well with CT and speckle-tracking 2D TTE. GLS analysis on 4D flow CMR allows for an integrative approach, integrating flow and functional data in a single sequence. Not applicable, observational study

Fundamental properties of five Kepler stars using global asteroseismic quantities and ground-based observations

We present an asteroseismic study of the solar-like stars KIC 11395018, KIC 10273246, KIC 10920273, KIC 10339342, and KIC 11234888 using short-cadence time series of more than eight months from the Kepler satellite. For four of these stars, we derive atmospheric parameters from spectra acquired with the Nordic Optical Telescope. The global seismic quantities (average large frequency separation and frequency of maximum power), combined with the atmospheric parameters, yield the mean density and surface gravity with precisions of 2% and ~0.03 dex, respectively. We also determine the radius, mass, and age with precisions of 2-5%, 7-11%, and ~35%, respectively, using grid-based analyses. We determine asteroseismic distances to these stars with a precision better than 10%, and constrain the stellar inclination for three of the stars. An Li abundance analysis yields an independent estimate of the age, but this is inconsistent with the asteroseismically determined age for one of the stars. We compare the results from five different grid-based analyses, and we find that they all provide radius and mass values to within 2.4sigma. The absence of a metallicity constraint when the average large frequency separation is measured with a precision of 1% biases the fitted radius and mass for the stars with non-solar metallicity (metal-rich KIC 11395018 and metal-poor KIC 10273246), while including a metallicity constraint reduces the uncertainties in both of these parameters by almost a factor of two. We found that including the average small frequency separation improves the determination of the age only for KIC 11395018 and KIC 11234888, and for the latter this improvement was due to the lack of strong atmospheric constraints. (Abridged).Comment: accepted A&A, 14 two-column pages + appendix, 5 figures, 15 table

A pair of Sub-Neptunes transiting the bright K-dwarf TOI-1064 characterised with CHEOPS

Funding: TGW, ACC, and KH acknowledge support from STFC consolidated grant numbers ST/R000824/1 and ST/V000861/1, and UKSA grant ST/R003203/1.We report the discovery and characterization of a pair of sub-Neptunes transiting the bright K-dwarf TOI-1064 (TIC 79748331), initially detected in the Transiting Exoplanet Survey Satellite (TESS) photometry. To characterize the system, we performed and retrieved the CHaracterising ExOPlanets Satellite (CHEOPS), TESS, and ground-based photometry, the High Accuracy Radial velocity Planet Searcher (HARPS) high-resolution spectroscopy, and Gemini speckle imaging. We characterize the host star and determine Teff,⋆=4734±67K⁠, R⋆=0.726±0.007R⊙⁠, and M⋆=0.748±0.032M⊙⁠. We present a novel detrending method based on point spread function shape-change modelling and demonstrate its suitability to correct flux variations in CHEOPS data. We confirm the planetary nature of both bodies and find that TOI-1064 b has an orbital period of Pb = 6.44387 ± 0.00003 d, a radius of Rb = 2.59 ± 0.04 R⊕, and a mass of Mb=13.5+1.7−1.8 M⊕, whilst TOI-1064 c has an orbital period of Pc=12.22657+0.00005−0.00004 d, a radius of Rc = 2.65 ± 0.04 R⊕, and a 3σ upper mass limit of 8.5 M⊕. From the high-precision photometry we obtain radius uncertainties of ∼1.6 per cent, allowing us to conduct internal structure and atmospheric escape modelling. TOI-1064 b is one of the densest, well-characterized sub-Neptunes, with a tenuous atmosphere that can be explained by the loss of a primordial envelope following migration through the protoplanetary disc. It is likely that TOI-1064 c has an extended atmosphere due to the tentative low density, however further radial velocities are needed to confirm this scenario and the similar radii, different masses nature of this system. The high-precision data and modelling of TOI-1064 b are important for planets in this region of mass–radius space, and it allow us to identify a trend in bulk density–stellar metallicity for massive sub-Neptunes that may hint at the formation of this population of planets.Publisher PDFPeer reviewe

Manufacturing variability; effects and characterization through text-mining

Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and Society, 2019Thesis: S.M., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2019Cataloged from PDF version of thesis.Includes bibliographical references (pages 77-89).Researchers and developers of new materials and processes often underestimate or neglect the effects of manufacturing variability and, as a result, make overly optimistic assumptions about their technologies. In this thesis, I explore the effects of manufacturing variability and find ways to characterize the manufacturing variability of emerging manufacturing processes. I develop a framework that connects manufacturing variability to environmental impact and economic costs through the concept of overdesign. I study examples using this framework and find that around 19% of concrete production is used solely to overcome issues of manufacturing variability, and that reducing the variability when producing fiber composite parts for a Boeing 787 reduces fuel consumption by millions of dollars and saves ktons of CO₂ from entering the atmosphere. I further explore the effects of manufacturing variability by considering its impacts on the commercialization process of new technologies.I consider Additive Manufacturing (AM), a promising technology, and argue that this technology has not reached commercial traction in great part due to our lack of understanding of the uncertainty associated with this process. I draw parallels to fiber composites, which faced similar issues in the 1980s before a collaborative effort, through the Advanced Composite Technology (ACT) and Advanced General Aviation Technology Experiments (AGATE) programs, was able to solve many of these challenges. Finally, I consider the volumes of data available in published documents and analyze whether it is possible to extract this information using text mining techniques, and to use these data to characterize the manufacturing variability of upcoming technologies. Some important challenges obstruct our ability to extract all the important information from these documents, but important steps are made to remove some of these challenges and I demonstrate that useful information can be extracted.Manufacturing engineers view processes as stochastic rather than deterministic. I ultimately argue for this view to also be adopted by environmentalists, materials researchers, and decision makers. I also further develop methods to extract and utilize manufacturing variation information.by Alexander van Grootel.S.M. in Technology and PolicyS.M.S.M.inTechnologyandPolicy Massachusetts Institute of Technology, School of Engineering, Institute for Data, Systems, and SocietyS.M. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Scienc

Simulating build to order strategies, capacity estimations and impacts of batching

Thesis: M. Eng. in Advanced Manufacturing and Design, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 96-98).When a startup scales up its enterprise the manufacturing system used to govern the production process should be robust enough to scale up with it. NVBOTS is in a position where it plans to scale up production by an order of magnitude within a few months. NVBOTS's manufacturing systems should therefore be reevaluated to ensure its design will meet requirements. In order to model the production process at NVBOTS a discrete event manufacturing simulation is developed. Both a Push system and a Build to Order (BtO) system are initially considered. The trade-offs that exist in these policies are identified and analyzed. A recommendation is made to adopt a BtO policy and to build in a batch size of one. Based on the feedback from NVBOTS an advanced model is then developed, which incorporates some benefit of batching. The effects of batch size on lead time, inventory level and capacity are investigated. Even when assuming a 30% setup time for assembly steps, the optimal batch size with regards to lead time or inventory levels remains at one. However, it is found that batching has a significant impact on the capacity of the system. The advanced model also introduces a new policy named Sell x Build y (SxBy, e.g. S1B6), which allows NVBOTS to operate in larger batches by minimizing the effect on lead time while keeping inventory roughly constant. With the current labor levels, and using a S1B6 policy, the model estimates a maximum capacity of around 23 printers per month. The expected 99 percentile lead time of this policy is roughly 11 work days. The work described in this thesis covers roughly half of the project on manufacturing systems at NVBOTS. The other half is covered in Yugal Raj Jain's thesis [1]. Jain's thesis focuses on multiple product lines and late-stage differentiation, and analyses CONWIP and CONWIP-BtO policies. In contrast, this thesis focuses on the capacity at the current facility and the policies which NVBOTS should look to adopt in the short term. The policies that this thesis considers includes Push, BtO and SxBy policies.by Alexander Willem Anton van Grootel.M. Eng. in Advanced Manufacturing and Desig

A search for transiting planets around hot subdwarfs : I. Methods and performance tests on light curves from Kepler, K2, TESS, and CHEOPS

Context. Hot subdwarfs experienced strong mass loss on the red giant branch (RGB) and are now hot and small He-burning objects. These stars constitute excellent opportunities for addressing the question of the evolution of exoplanetary systems directly after the RGB phase of evolution.Aims. In this project we aim to perform a transit survey in all available light curves of hot subdwarfs from space-based telescopes (Kepler, K2, TESS, and CHEOPS) with our custom-made pipeline SHERLOCK in order to determine the occurrence rate of planets around these stars as a function of orbital period and planetary radius. We also aim to determine whether planets that were previously engulfed in the envelope of their red giant host star can survive, even partially, as a planetary remnant.Methods. For this first paper, we performed injection-and-recovery tests of synthetic transits for a selection of representative Kepler, K2, and TESS light curves to determine which transiting bodies in terms of object radius and orbital period we will be able to detect with our tools. We also provide estimates for CHEOPS data, which we analyzed with the pycheops package.Results. Transiting objects with a radius ≲1.0 R⊕ can be detected in most of the Kepler, K2, and CHEOPS targets for the shortest orbital periods (1 d and shorter), reaching values as low as ~0.3 R⊕ in the best cases. Sub-Earth-sized bodies are only reached for the brightest TESS targets and for those that were observed in a significant number of sectors. We also give a series of representative results for larger planets at greater distances, which strongly depend on the target magnitude and on the length and quality of the data.Conclusions. The TESS sample will provide the most important statistics for the global aim of measuring the planet occurrence rate around hot subdwarfs. The Kepler, K2, and CHEOPS data will allow us to search for planetary remnants, that is, very close and small (possibly disintegrating) objects

Inorganic Materials Synthesis Planning with Literature-Trained Neural Networks

Copyright © 2020 American Chemical Society. Leveraging new data sources is a key step in accelerating the pace of materials design and discovery. To complement the strides in synthesis planning driven by historical, experimental, and computed data, we present an automated, unsupervised method for connecting scientific literature to inorganic synthesis insights. Starting from the natural language text, we apply word embeddings from language models, which are fed into a named entity recognition model, upon which a conditional variational autoencoder is trained to generate syntheses for any inorganic materials of interest. We show the potential of this technique by predicting precursors for two perovskite materials, using only training data published over a decade prior to their first reported syntheses. We demonstrate that the model learns representations of materials corresponding to synthesis-related properties and that the model's behavior complements the existing thermodynamic knowledge. Finally, we apply the model to perform synthesizability screening for proposed novel perovskite compounds

A new dynamical modeling of the WASP-47 system with CHEOPS observations

Among the hundreds of known hot Jupiters (HJs), only five have been found to have companions on short-period orbits. Within this rare class of multiple planetary systems, the architecture of WASP-47 is unique, hosting an HJ (planet-b) with both an inner and an outer sub-Neptunian mass companion (-e and -d, respectively) as well as an additional non-transiting, long-period giant (-c). The small period ratio between planets -b and -d boosts the transit time variation (TTV) signal, making it possible to reliably measure the masses of these planets in synergy with the radial velocity (RV) technique. In this paper, we present new space- and ground-based photometric data of WASP-47b and WASP-47-d, including 11 unpublished light curves from the ESA mission CHaracterising ExOPlanet Satellite (CHEOPS). We analyzed the light curves in a homogeneous way together with all the publicly available data to carry out a global N-body dynamical modeling of the TTV and RV signals. We retrieved, among other parameters, a mass and density for planet -d of Md = 15.5 ± 0.8 M⊕ and ρd = 1.69 ± 0.22 g cm−3, which is in good agreement with the literature and consistent with a Neptune-like composition. For the inner planet (-e), we found a mass and density of Me = 9.0 ± 0.5 M⊕ and ρe = 8.1 ± 0.5 g cm−3, suggesting an Earth-like composition close to other ultra-hot planets at similar irradiation levels. Though this result is in agreement with previous RV plus TTV studies, it is not in agreement with the most recent RV analysis (at 2.8σ), which yielded a lower density compatible with a pure silicate composition. This discrepancy highlights the still unresolved issue of suspected systematic offsets between RV and TTV measurements. In this paper, we also significantly improve the orbital ephemerides of all transiting planets, which will be crucial for any future follow-up.ISSN:0004-6361ISSN:1432-074