Notebook · The Month Under the Beam

The Month Under the Beam — August 2026

A roundup of recent papers in which the scanning electron microscope did real work, read from the operator's chair — plus the meetings worth putting on the calendar. First edition, so it casts a slightly wider net across 2026 than later ones will.

The rule for inclusion is simple: the SEM has to have mattered. Not "Fig. S14 is an SEM image," but a paper where the microscope settled the question, or where the way it was used is worth stealing. Five this month, spanning a kidney, a steel, a fungus, an aluminium alloy, and the instrument itself. Every DOI below was resolved before it was cited; if one of them has since moved, tell us.

1. SE2 are not just noise — a rethink of where ultrahigh resolution comes from

H. T. Chen, Y. B. Zou, B. Da, Z. J. Ding et al., "A Quest for the Mechanism of Ultrahigh Resolution SEM Imaging," Advanced Science (published 26 January 2026). doi:10.1002/advs.202516341

The textbook story — the one we tell in our own SE-vs-BSE guide — is that SE1, born under the probe, carry the resolution, while SE2, born where backscattered electrons exit, smear it. Chen and colleagues push on that with Monte Carlo simulations that keep SE1 and SE2 strictly separate across beam energies from 0.1 to 30 keV, and report that surface morphology modulates the spatial distribution of SE2 in a way that can contribute to resolution rather than only degrade it — enough, in their modelling of gold nanoparticles on carbon, to account for sub-nanometre detail. The bench-level moral is not that SE2 are your friend (on a bulk, flat, multi-phase sample they are still a composition wash), but that the SE1/SE2 division is a model, and models have edges. Worth reading before you next explain "why in-lens images look different."

2. Low-kV SE imaging of the kidney — beating erythrocyte charging without perfusion

S. Conti, A. Benigni, G. Remuzzi et al., "A scanning electron microscopy-based approach to explore subpodocyte space remodeling in diabetic kidneys of mice and humans," Scientific Reports (21 February 2026). doi:10.1038/s41598-026-40816-9

This is a sample-prep paper wearing a nephrology coat. The subpodocyte space is a narrow compartment in the glomerulus usually measured by TEM, slowly. The authors instead image non-perfused kidney tissue — mouse and human — by secondary-electron SEM at 4–7 kV, and report that the charging artifacts from residual red blood cells, which would normally force perfusion or rescue coating, could be managed by beam-parameter choice alone. With that protocol they quantify the space quickly enough to compare cohorts, and find it markedly enlarged in diabetic BTBR ob/ob mice and in a diabetic patient relative to controls — proposing it as an early ultrastructural marker. The part to steal: the explicit trade of kV and current against charging on material you cannot coat away, and the willingness to write the compromise down as a method.

3. Watching a dual-phase steel fail, one interrupted punch at a time

A. Alsharif, S. Q. Moinuddin, C. Pinna et al., "Small punch testing and scanning electron microscopy analysis of damage evolution in dual-phase steel," Scientific Reports (17 February 2026). doi:10.1038/s41598-026-40489-4

Small-punch testing deforms a coin-sized disc with a hemispherical punch; here the tests are interrupted at increasing displacements and the surface is imaged in the SEM at each stop, then fractured specimens are sectioned for through-thickness views. The sequence shows damage starting early at ferrite–martensite interfaces — strain incompatibility between the soft and hard phases — followed by void growth and coalescence in the ferrite, with cracks running from the punch-contact face toward the far surface; martensite cracking is confined to the early stages, and later damage growth is ferrite-dominated. It is a tidy example of the "interrupt, image, continue" pattern that turns a mechanical test into a movie, and of why a polished cross-section and a BSE detector are the fastest route to reading a two-phase microstructure.

4. Earthstar fungi, identified by SEM, a deep-learning model, and DNA — together

E. Kumru, Ş. Altaş, G. Ediş et al., "Integrating scanning electron microscopy, explainable deep learning, and ITS sequencing for accurate identification in some species Geastrum," Scientific Reports (13 May 2026). doi:10.1038/s41598-026-53120-3

Geastrum — the earthstars — are notoriously hard to tell apart by eye. This study stacks three methods: SEM imaging of the specimens, a deep-learning classifier whose decisions are made inspectable (the "explainable" part, so you can see which image regions drove the call), and ITS sequencing as the molecular ground truth. The point for microscopists is less the fungi than the architecture: the SEM provides morphology at a scale the eye cannot, the model makes it reproducible, and the sequencing keeps everyone honest. Expect to see this pattern — micrograph, interpretable model, orthogonal confirmation — spread well beyond mycology.

5. Low-voltage SEM–EDS for dispersoids in aluminium alloys

J. Tschirhart, E. Vandale, P. Gauthier et al., "Low Voltage SEM–EDS Methodology for Quantitative Characterization of Dispersoids in Aluminum Alloys," Microscopy and Microanalysis 32 (Supplement 1), M&M 2026 proceedings (July 2026). doi:10.1093/mam/ozag053.236

A proceedings abstract rather than a full paper, so we will not overclaim its contents — but the problem it names is one every aluminium person knows. Dispersoids are the sub-micron particles that pin grain boundaries and set recrystallization behaviour, and at a conventional 15–20 kV the X-ray generation volume swallows them whole: the spectrum is mostly matrix. Dropping the accelerating voltage shrinks that volume toward the particle size, which is the whole premise of a low-voltage EDS methodology, at the cost of losing the higher-energy lines and fighting lower count rates. If you analyse fine second phases in any light-metal matrix, this is the kind of method to chase into the full write-up.

Meetings & events

Upcoming, with verified dates; regional societies are listed by MSA at microscopy.org/local-affiliated-societies and most of them run an autumn meeting — check yours.