We report on the development of a miniature, flexible, fiber-optic scanning endoscope for two-photon fluorescence imaging. The endoscope uses a tubular piezoelectric actuator for achieving two-dimensional beam scanning and a double-clad fiber for delivery of the excitation light and collection of two-photon fluorescence. Real-time imaging of fluorescent beads and cancer cells has been performed.

The thermodynamics for the first electron transfer step for sulfide and oxygen indicates that the reaction is unfavorable as unstable superoxide and bisulfide radical ions would need to be produced. However, a two-electron transfer is favorable as stable S(0) and peroxide would be formed, but the partially filled orbitals in oxygen that accept electrons prevent rapid kinetics. Abiotic sulfide oxidation kinetics improve when reduced iron and/or manganese are oxidized by oxygen to form oxidized metals which in turn oxidize sulfide. Biological sulfur oxidation relies on enzymes that have evolved to overcome these kinetic constraints to affect rapid sulfide oxidation. Here we review the available thermodynamic and kinetic data for H 2 S and HS• as well as O 2 , reactive oxygen species, nitrate, nitrite, and NO x species. We also present new kinetic data for abiotic sulfide oxidation with oxygen in trace metal clean solutions that constrain abiotic rates of sulfide oxidation in metal free solution and agree with the kinetic and thermodynamic calculations. Moreover, we present experimental data that give insight on rates of chemolithotrophic and photolithotrophic sulfide oxidation in the environment. We demonstrate that both anaerobic photolithotrophic and aerobic chemolithotrophic sulfide oxidation rates are three or more orders of magnitude higher than abiotic rates suggesting that in most environments biotic sulfide oxidation rates will far exceed abiotic rates due to the thermodynamic and kinetic constraints discussed in the first section of the paper. Such data reshape our thinking about the biotic and abiotic contributions to sulfide oxidation in the environment.

Any beneficial effect of creatine at 5 g per day in ALS must be small. Other agents should be considered in future studies of therapeutic agents to address mitochondrial dysfunction in ALS. In addition, motor unit number estimation may be a useful outcome measure for future clinical trials in ALS.

Intertidal aquifers host a reactive zone comprised of Fe mineral‐coated sands where fresh and saline groundwaters mix. This zone may significantly influence the export of C, N, P, Fe, and other metals in submarine groundwater discharge (SGD). Toward determining the roles of microbes in Fe and S mineralization, and the interplay of microbiology with geochemistry and physical hydrology, we conducted a biogeochemical study of pore waters at Cape Shores, Delaware. Here, fresh groundwater provides Fe(II), which precipitates as FeIIIOOH predominantly through microbial Fe(II) oxidation. Candidate division OP3 was the dominant microbial group associated with Fe(II)‐ and Fe(III)‐rich regions of the aquifer, suggesting that this uncharacterized phylum may be involved in Fe(II) oxidation. Saline water brings O2, sulfate, and organic C into the intertidal mixing zone. Microbial reduction of sulfate produces sulfide that is transported to the Fe‐mineralized zone leading to the transformation of FeOOH to Fe(II) sulfides. Microbial populations are structured by the availability of chemical species supplied along groundwater flow paths. Seasonal changes in the relative supply of fresh and saline groundwater affect solute fluxes, and therefore, microbial controls on the location and composition of the Fe‐mineralized zone. Ultimately, the composition, extent, and dynamics of the Fe‐mineralized zone will affect the sequestration, affinity, and residence time of solutes bound for export to coastal oceans through SGD.

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