We have measured reaction rate constants for CO and CO reacting with N and O atoms using a selected ion flow tube apparatus equipped with a microwave discharge atom source. Experimental work was supplemented by molecular structure calculations. Calculated pathways show the sensitivity of kinetic barriers to theoretical methods and imply that high-level ab initio methods are required for accurate energetics. We report room-temperature rate constants of 1.0 ± 0.4 × 10 cm s and 4.0 ± 1.6 × 10 cm s for the reactions of CO with N and O atoms, respectively, and 8.0 ± 3.0 × 10 cm s and 2.0 ± 0.8 × 10 cm s for the reactions of CO with N and O atoms, respectively. The reaction of CO + O is observed to yield O exclusively. These values help resolve discrepancies in the literature and are important for modeling of the Martian atmosphere.

The gut microbiota is composed mainly of members from the phyla Bacteroides and Firmicutes. Others have shown a correlation of obesity with a reduction in the Bacteroides’ ability to grow normally and maintain their role in the gut. Sucralose is a ‘non‐metabolizable’ chlorinated sucrose derivative and the synthesized ingredient in the artificial sweetener Splenda®. Turbidity data obtained from active cultures showed a differential effect of sucralose on the growth curves between members of these Phyla. Sucralose had little effect on two Firmicutes, E. faecalis and C. sordellii, while there was a concentration dependent inhibition of growth of Bacteroides, B. fragilis and B. uniformis. Preliminary results of sucrase enzyme assays may demonstrate considerable competitive inhibition in the presence of sucralose. Furthermore, preliminary transport tests may have displayed differential results between the two phyla suggesting two putative means of metabolic inhibition that explain the reported growth curves. It must be considered that sucralose has the ability to alter gut flora composition by these differential metabolic findings and the negative health impacts from this imbalance must be addressed.

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