A Retrofittable Photoelectron Gun for Low-Voltage Imaging Applications in the Scanning Electron Microscope.

Low-voltage scanning electron microscopy is a powerful tool for examining surface features and imaging beam-sensitive materials. Improving resolution during low-voltage imaging is then an important area of development. Decreasing the effect of chromatic aberration is one solution to improving the resolution and can be achieved by reducing the energy spread of the electron source.

Cost and Capability Compromises in STEM Instrumentation for Low-Voltage Imaging.

Low-voltage transmission electron microscopy (≤80 kV) has many applications in imaging beam-sensitive samples, such as metallic nanoparticles, which may become damaged at higher voltages. To improve resolution, spherical aberration can be corrected for in a scanning transmission electron microscope (STEM); however, chromatic aberration may then dominate, limiting the ultimate resolution of the microscope. Using image simulations, we examine how a chromatic aberration corrector, different objective lenses, and different beam energy spreads each affect the image quality of a gold nanoparticle imaged at low voltages in a spherical aberration-corrected STEM.

Molecular epidemiology of Rhodococcus equi based on traA, vapA, and vapB virulence plasmid markers.

Molecular typing of the actinomycete Rhodococcus equi is insufficiently developed, and little is known about the epidemiology and transmission of this multihost pathogen. We report a simple, reliable polymerase chain reaction typing system for R. equi based on 3 plasmid gene markers: traA from the conserved conjugal transfer machinery and vapA and vapB, found in 2 different plasmid subpopulations.