89 research outputs found
A deep learning approach for determining the chiral indices of carbon nanotubes from high-resolution transmission electron microscopy images
Chiral indices determine important properties of carbon nanotubes (CNTs).
Unfortunately, their determination from high-resolution transmission electron
microscopy (HRTEM) images, the most accurate method for assigning chirality, is
a tedious task. We develop a Convolutional Neural Network that automatizes this
process. A large and realistic training data set of CNT images is obtained by
means of atomistic computer simulations coupled with the multi-slice approach
for image generation. In most cases, results of the automated assignment are in
excellent agreement with manual classification, and the origin of failures is
identified. The current approach, which combines HRTEM imaging and deep
learning algorithms allows the analysis of a statistically significant number
of HRTEM images of carbon nanotubes, paving the way for robust estimates of
experimental chiral distributions.Comment: for use of the discussed computer code, please contact the
corresponding autho
Intracellular degradation of functionalized carbon nanotube/iron oxide hybrids is modulated by iron via Nrf2 pathway.
The in vivo fate and biodegradability of carbon nanotubes is still a matter of debate despite tremendous applications. In this paper we describe a molecular pathway by which macrophages degrade functionalized multi-walled carbon nanotubes (CNTs) designed for biomedical applications and containing, or not, iron oxide nanoparticles in their inner cavity. Electron microscopy and Raman spectroscopy show that intracellularly-induced structural damages appear more rapidly for iron-free CNTs in comparison to iron-loaded ones, suggesting a role of iron in the degradation mechanism. By comparing the molecular responses of macrophages derived from THP1 monocytes to both types of CNTs, we highlight a molecular mechanism regulated by Nrf2/Bach1 signaling pathways to induce CNT degradation via NOXjournal article2017 Jan 252017 01 25importe
Liquid metal nanodroplet dynamics inside nanocontainers
Here we report direct observations of spatial movements of nanodroplets of Pb metal trapped inside sealed
carbon nanocontainers. We find drastic changes in the mobility of the liquid droplets as the particle size
increases from a few to a few ten nanometers. In open containers the droplet becomes immobile and readily
evaporates to the vacuum environment. The particle mobility strongly depends on confinement, particle
size, and wetting on the enclosed surface. The collisions between droplets increase mobility but the tendency
is reversed if collisions lead to droplet coalescence. The dynamics of confined nanodroplets could provide
new insights into the activity of nanostructures in spatially constrained geometries
Single-nanoparticle phase transitions visualized by four-dimensional electron microscopy
The advancement of techniques that can probe the behaviour of individual nanoscopic objects is of paramount importance
in various disciplines, including photonics and electronics. As it provides images with a spatiotemporal resolution,
four-dimensional electron microscopy, in principle, should enable the visualization of single-nanoparticle structural
dynamics in real and reciprocal space. Here, we demonstrate the selectivity and sensitivity of the technique by visualizing
the spin crossover dynamics of single, isolated metalâorganic framework nanocrystals. By introducing a small aperture in
the microscope, it was possible to follow the phase transition and the associated structural dynamics within a single
particle. Its behaviour was observed to be distinct from that imaged by averaging over ensembles of heterogeneous
nanoparticles. The approach reported here has potential applications in other nanosystems and those that undergo
(bio)chemical transformations
Recording low and high spatial frequencies in exit wave reconstructions.
Aberration corrected Transmission Electron Microscope (TEM) images can currently resolve information at significantly better than 0.1 nm. Aberration corrected imaging conditions seek to optimize the transfer of high-resolution information but in doing so they prevent the transfer of low spatial frequency information. To recover low spatial frequency information, aberration corrected images must be acquired at a large defocus which compromises high spatial frequency information transfer. In this paper we present two a posteriori solutions to this problem in which the information bandwidth in an exit wave reconstruction is increased. In the first we reconstruct the electron exit wavefunction from two focal series datasets, with different, uniform focal steps, experimentally demonstrating that the width of the transfer interval can be extended from 0.2 nmâ»Âč (âŒ5 nm) to better than 10 nmâ»Âč (0.1 nm). In the second we outline the use of a focal series recorded with a non-uniform focal step to recover a wider range of spatial frequencies without the need for a large number of images. Using simulated data we show that using this non-uniform focal step the spatial frequency interval for a five image data set may be increased to between 0.25 nmâ»Âč (4 nm) and 8.3 nmâ»Âč (0.12 nm) compared to between 0.74 nmâ»Âč (1.4 nm) and 8.3 nmâ»Âč (0.12 nm) for the standard focal series geometry
Nanoscale temperature measurement during temperature controlled in situ TEM using Al plasmon nanothermometry
International audienc
Attachment of iron oxide nanoparticles to carbon nanofibers studied by in-situ liquid phase transmission electron microscopy
International audienc
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