For estimations of P-T conditions of igneous and metamorphic rocks, Fe31 in coexisting minerals is either assumed to be zero or is calculated from electron microprobe analyses (EMPA) based upon stoichiometry and charge balance. Geothermobarometers that involve Fe21-Mg21 exchange can be significantly affected by either neglecting Fe31 or using incorrect values. Ratios of Fe31/SFe in garnet and c...

Recent developments in analytical instrumentation have led to revolutionary discoveries in cosmochemistry. Instrumental advances have been made along two lines: (i) increase in spatial resolution and sensitivity of detection, allowing for the study of increasingly smaller samples, and (ii) increase in the precision of isotopic analysis that allows more precise dating, the study of isotopic hete...

The properties of many biological materials often depend on the spatial distribution and concentration of the trace elements present in a matrix. Scientists have over the years tried various techniques including classical physical and chemical analyzing techniques each with relative level of accuracy. However, with the development of spatially sensitive submicron beams, the nuclear microprobe t...

1. The concentrations of sodium, potassium, chloride and water in the cells, secretory canaliculi and the lumen of Calliphora salivary glands have been measured by microprobe analysis of frozen-hydrated sections. Free concentrations of K+ and Cl~ in all three compartments were measured with ion-selective microelectrodes. 2. Most of the quantitative data from the two techniques are in close agre...

X-ray absorption spectroscopy (XAS) is proving invaluable in determining the average chemical form of metals or metalloids in intact biological tissues. As most tissues have spatial structure, there is great additional interest in visualizing the spatial location of the metal(loid) as well as its chemical forms. XAS imaging gives the opportunity of producing maps of specific chemical types of e...

Microprobes are used to repair neuronal injury by recording electrical signals from neuronal cells around the sur‐ face of the device. Following implantation into the brain, the immune response results in formation of scar tissue around the microprobe. However, neurons must be in close proximity to the microprobe to enable signal recording. A common reason for failure of microprobes is impaired...