Search for: All records

Abstract Point defects typically reduce the thermal conductivity (κ) of a crystal due to increased scattering of heat‐carrying phonons, a mechanism that is well understood and widely used to enhance or impede heat transfer in the material for different applications. Here an opposite effect is reported where the introduction of point defects in graphite with energetic particle irradiation increases its cross‐planeκby nearly a factor of two, from 10.8 to 18.9 W m K⁻¹at room temperature. Integrated differential phase contrast imaging with scanning transmission electron microscopy revealed the creation of spiro interstitials in graphite by the irradiation. The enhancement inκis attributed to a remarkable mechanism that works to the benefit of phonon propagation in both the harmonic and anharmonic terms: these spiro interstitial defects covalently bridge neighboring basal planes, simultaneously enhancing acoustic phonon group velocity and reducing phonon–phonon scattering in the graphite structure. The enhancement ofκreveals an unconventional role of lattice defects in heat conduction, i.e., easing the propagation of heat‐carrying phonons rather than impeding them in layered materials, inspiring their applications for thermal management in heavily radiative environments. 

The analysis of live-cell single-molecule imaging experiments can reveal valuable information about the heterogeneity of transport processes and interactions between cell components. These characteristics are seen as motion changes in the particle trajectories. Despite the existence of multiple approaches to carry out this type of analysis, no objective assessment of these methods has been performed so far. Here, we report the results of a competition to characterize and rank the performance of these methods when analyzing the dynamic behavior of single molecules. To run this competition, we implemented a software library that simulates realistic data corresponding to widespread diffusion and interaction models, both in the form of trajectories and videos obtained in typical experimental conditions. The competition constitutes the first assessment of these methods, providing insights into the current limitations of the field, fostering the development of new approaches, and guiding researchers to identify optimal tools for analyzing their experiments.