Microscale Measurement and Visualization of Sulfide δS Using Photographic Film Sulfide Capture Coupled with Laser Ablation Multicollector Inductively Coupled Plasma Mass Spectrometry.

Measurements of the isotopic composition of sulfate and sulfide have been essential to uncovering the microbial and geochemical processes that drive Earth's sulfur cycle. These processes routinely operate over submillimeter spatial scales in anaerobic environments, necessitating sulfur isotopic measurement techniques that can identify isotopic variability over equivalently small scales. Here we present a new method for small-scale (10 μm) measurements of δS using black and white photographic film sulfide capture coupled with δS determination using laser ablation multicollector inductively coupled plasma mass spectrometry.

Temporal evolution and variability of dissolved inorganic nitrogen in beach pore water revealed using radon residence times.

We coupled measurements of beach pore water residence time, determined using the radioisotopic tracer (222)Rn, with dissolved carbon and nitrogen chemistry to identify the temporal evolution and variability of dissolved inorganic nitrogen (DIN) concentrations in beach pore water along the Santa Barbara, California coastline. Pore water dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) ratios (DOC:TDN) were negative exponentially correlated with residence time. Mean pore water residence times were positively correlated with tidal amplitudes, and ranged from 4.

Molecular forms of acetylcholinesterases in Alzheimer's disease.

In this study, we examined 26 cases of Alzheimer's disease (AD) and 14 age-matched controls. In Brodmann area 21 cerebral cortex of the AD cases, there was no change in soluble G1 and G4 acetylcholinesterase (AChE) (EC 3.1.