Soot-in-Oil 3D Volume Reconstruction Through the Use of Electron Tomography: An Introductory Study

Progress towards a methodology for high throughput 3D reconstruction of soot nanoparticles via electron tomography

“…The apparent morphology of a particle in a projection can change considerably if the angle of projection is altered, and as such the value of any measured morphological properties would also change considerably. Previous work by the authors observed that commonly measured morphological properties could vary by up to 60% for the same particle when projection angles over a ±60° range were considered (La Rocca et al ., ). Work by Adachi also found that 2D‐derived properties are highly sensitive to the angle of projection, with similar levels of variability (Adachi et al ., ).…”

“…A small number of researchers (Medalia, ;, Adachi et al ., ), including the authors (La Rocca et al ., ), have expressed concern over the validity of 3D properties inferred from just a single projection, though in the vast majority of publications this is ignored. The notion is that it can be considered incorrect to only use values measured from a single 2D projection of a particle, given that all possible 2D projections are equally valid representations of the 3D structure and all involve the same lack of depth perception.…”

“…Whilst a handful of publications have proved that soot characterization through 3D volume reconstruction is possible (van Poppel et al ., ; Adachi et al ., ; La Rocca et al ., ), there remain a major challenge to be overcome before the technique becomes a viable alternative to 2D‐TEM, as the time required to produce the models is currently far too long for a statistically significant number of particles to be characterized.…”

“…Over the last few decades, TEM has been widely used for the detailed characterization of soot nanoparticles (Dobbins & Megaridis, ; Megaridis & Dobbins, ; Palotas et al ., ; Clague et al ., ; Su et al ., ; Devlin et al ., ; Lapuerta et al ., ; La Rocca et al ., ; La Rocca et al ., ; La Rocca et al ., ). From TEM images a variety of parameters may be measured (volume, surface area, radius of gyration, fractal dimension, skeletal length etc.).…”

Ecotoxicity testing of microplastics: Considering the heterogeneity of physicochemical properties

“…Although surface area is not generally reported in MP studies, for primary microbeads it can be calculated based on spherical equivalent diameter, but for irregularly shaped secondary MPs this can cause an overestimation. For example, La Rocca et al (2015) found that for nanoscale soot particles, surface area estimates using geometrical estimates can lead to a 7-fold overestimation of the surface area, and a particle shape factor needs to be applied to correct for this.…”