Role of electronic thermal transport in amorphous metal recrystallization: a molecular dynamics study

Recrystallization of glasses is important in a wide range of applications including electronics and reactive materials. Molecular dynamics (MD) has been used to provide an atomic picture of this process, but prior work has neglected the thermal transport role of electrons, the dominant thermal carrier in metallic systems. We characterize the role of electronic thermal conductivity on the velocity of recrystallization in Ni using MD coupled to a continuum description of electronic thermal transport via a two-temperature model. Our simulations show that for strong enough coupling between electrons and ions, the increased thermal conductivity removes the heat from the exothermic recrystallization process more efficiently, leading to a lower effective temperature at the recrystallization front and, consequently, lower propagation velocity. We characterize how electron-phonon coupling strength and system size affects front propagation velocity. Interestingly, we find that initial recrystallization velocity increases with decreasing in system size due to higher overall temperatures. Overall, we show that a more accurate description of thermal transport due to the incorporation of electrons results in better agreement with experiments

Mobile devices for the remote acquisition of physiological and behavioral biomarkers in psychiatric clinical research

Psychiatric disorders are linked to a variety of biological, psychological, and contextual causes and consequences. Laboratory studies have elucidated the importance of several key physiological and behavioral biomarkers in the study of psychiatric disorders, but much less is known about the role of these biomarkers in naturalistic settings. These gaps are largely driven by methodological barriers to assessing biomarker data rapidly, reliably, and frequently outside the clinic or laboratory. Mobile health (mHealth) tools offer new opportunities to study relevant biomarkers in concert with other types of data (e.g., self-reports, global positioning system data). This review provides an overview on the state of this emerging field and describes examples from the literature where mHealth tools have been used to measure a wide array of biomarkers in the context of psychiatric functioning (e.g., psychological stress, anxiety, autism, substance use). We also outline advantages and special considerations for incorporating mHealth tools for remote biomarker measurement into studies of psychiatric illness and treatment and identify several specific opportunities for expanding this promising methodology. Integrating mHealth tools into this area may dramatically improve psychiatric science and facilitate highly personalized clinical care of psychiatric disorders

Orientation and morphology of Pt nanoparticles in γ-alumina processed via ion implantation and thermal annealing

Structure and chemistry of metal/metal-oxide interfaces are critical for many catalytic processes and sensing. Pristine interfaces of Pt and γ -Al2O3 were fabricated using high-energy ion implantation and thermal processing. Amorphous regions of alumina develop in single crystal α-alumina during Pt+ implantation and an 800 °C thermal treatment crystalizes amorphized alumina to γ -Al2O3 and allows Pt ions to precipitate within the developing γ -alumina, yielding Pt nanoparticle tetrahedra terminated by {111} surfaces. The phase of alumina that developed and the distribution, morphology, and orientation of Pt nanoparticles was determined using x-ray diffraction, Rutherford backscattering spectrometry, transmission electron microscopy and scanning transmission electron microscopy

Photometric Signature of Ultraharmonic Resonances in Barred Galaxies

Bars may induce morphological features, such as rings, through their resonances. Previous studies suggested that the presence of "dark gaps,"or regions of a galaxy where the difference between the surface brightness along the bar major axis and that along the bar minor axis is maximal, can be attributed to the location of bar corotation. Here, using GALAKOS, a high-resolution N-body simulation of a barred galaxy, we test this photometric method's ability to identify the bar corotation resonance. Contrary to previous work, our results indicate that "dark gaps"are a clear sign of the location of the 4:1 ultraharmonic resonance instead of bar corotation. Measurements of the bar corotation can indirectly be inferred using kinematic information, e.g., by measuring the shape of the rotation curve. We demonstrate our concept on a sample of 578 face-on barred galaxies with both imaging and integral field observations and find that the sample likely consists primarily of fast bars

Bridging Gaps in Multi-scale Materials Modeling with Machine and Transfer Learning

In 2011, the Materials Genome Initiative (MGI) was founded as an effort to unite and drive materials design at an unprecedented pace. By linking computational tools with experimental data, and aligning their data structures to match and interact, scientists across the world have been able to change the way they do science at a fundamental level. The 3 Mission Statements of the Materials Genome Initiative include: 1) Developing a Materials Innovation Infrastructure 2) Achieving National Goals with Advanced Materials 3) Equipping the Next-Generation Materials Workforce. Since the inception of the MGI the Materials Engineering community has developed numerous cyberinfrastructure repositories for experimental, and varied levels of computational data. This practice aligns with a separate initiative for Findable, Accessible, Interoperable, and Reproducible (F.A.I.R.) principles for data handling and science. By integrating the cyberinfrastructure efforts with continued collaboration from experimental and computational scientists we push the field to evolve improved workflows for research. This thesis is a collection of applied solutions for materials design with atomistic modeling, and machine learning (ML). In Part 1, we will discuss bridges for the gaps between atomistic simulation and experiment, and what it means for material solutions. A showcase of combining experimental information with ab initio electronic transport calculations will be discussed, as well as the principles of density functional theory (DFT) and molecular dynamics (MD) simulations. In Part 2, our focus will shift to applications of machine learning and the use of composition and chemical featurizers for materials design. Here we leverage cyberinfrastructure efforts with APIs and ML with transfer and active learning for efficient high-dimensional space exploration. In Part 3 local atomic environments and configurations, associative fingerprinting solutions, and workflows for designing deep learning (DL) interatomic potentials for MD are discussed. Finally, a brief section will conclude with efforts made to align with F.A.I.R. principles for Materials Engineering research, and educational development for Mission Statement 3 of the MGI