Characterization of Bacterial Magnetic Nanostructures Using High-Resolution Transmission Electron Microscopy and Off-Axis Electron Holography

Magnetotactic bacteria can be regarded as model systems for studying the structural, chemical, and magnetic properties of arrangements of ferrimagnetic iron oxide and sulfide nanocrystals. The aim of the present chapter is to show how the size, shape, crystal structure, crystallographic orientation, and spatial arrangement of bacterial magnetite (Fe 3 O 4) and greigite (Fe3S4) crystals affect their magnetic properties. We present recent results obtained using transmission electron microscopy (TEM) techniques, including high-resolution TEM imaging and off-axis electron holography

The synthesis of organic and inorganic compounds in evolved stars

Recent isotopic analysis of meteorites and interplanetary dust has identified solid-state materials of pre-solar origin. We can now trace the origin of these inorganic grains to the circumstellar envelopes of evolved stars. Moreover, organic (aromatic and aliphatic) compounds have been detected in proto-planetary nebulae and planetary nebulae, which are the descendants of carbon stars. This implies that molecular synthesis is actively happening in the circumstellar environment on timescales as short as several hundred years. The detection of stellar grains in the Solar System suggests that they can survive their journey through the interstellar medium and that they are a major contributor of interstellar grains.link_to_subscribed_fulltex