a b s t r a c t a r t i c l e i n f o Available online xxxx Keywords: Platinum Catalysts Hydrogen pumping Fluidized bed Fluidization Atomic layer depositionPlatinum nanoparticle catalysts for electrochemical hydrogen pumping were synthesized on a functionalized powder carbon substrate (XC72R) using atomic layer deposition (ALD) in a fluidized bed reactor (FBR). Trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtMe 3 ) was used as the reagent for platinum delivery. Following deposition, MeCpPtMe 3 ligands were combusted or hydrogenated to yield platinum on the XC72R surface. Reactions throughout the ALD cycle were monitored using mass spectrometry and IR spectroscopy to clarify the deposition chemistry. The resultant platinum catalysts were compared to commercial products in hydrogen pumping tests. Hydrogenation made finer, more dispersed, platinum nanoparticles that performed similarly to their commercial equivalent when pumping hydrogen. Conversely, oxygenation made a coarser catalyst that underperformed its commercial equivalent. Thus, altering chemistries shows potential for improving ALD catalyst performance.

The hippocampus has become a significant target of stress research in recent years because of its role in cognitive functioning, neuropathology, and regulation of the hypothalamic-pituitary-adrenal (HPA) axis. Despite the pervasive impact of stress on psychiatric and neurological disease, many of the circuit-and cell-dependent mechanisms giving rise to the limbic regulation of the stress response remain unknown.Hippocampal excitatory neurons generally express high levels of glucocorticoid receptors (GRs) and are therefore positioned to respond directly to serum glucocorticoids. These neurons are, in turn, regulated by neighboring interneurons, subtypes of which have been shown to respond to stress exposure. However, GR expression among hippocampal interneurons is not well characterized. To determine whether key interneuron populations are direct targets for glucocorticoid action, we used two transgenic mouse lines to label parvalbumin-positive (PV+) and somatostatin-positive (SST+) interneurons. GR immunostaining of labeled interneurons was characterized within the dorsal and ventral dentate hilus, dentate cell body layer, and CA1 and CA3 stratum oriens and stratum pyramidale. While nearly all hippocampal SST+ interneurons expressed GR across all regions, GR labeling of PV+ interneurons showed considerable subregion variability. The percentage of PV+, GR+ cells was highest in the CA3 stratum pyramidale and lowest in the CA1 stratum oriens, with other regions showing intermediate levels of expression. Together, these findings indicate that, under baseline conditions, hippocampal SST+ interneurons are a ubiquitous glucocorticoid target, while only distinct populations of PV+ interneurons are direct targets. This anatomical diversity suggests functional differences in the regulation of stress-dependent hippocampal responses.

Proton exchange membrane fuel cell (PEMFC) catalysts manufactured using atomic layer deposition (ALD) on unmodified and functionalized carbon were compared to a commercial catalyst in half-and whole-cell tests. Half-cell tests showed the ALD catalyst performed better or comparable to a commercial catalyst. Conversely, whole-cell tests revealed flooding in the ALD catalyst produced on functionalized carbon. Residual functional groups had reduced the hydrophobicity, and rendered this catalyst impractical for use in whole-cell PEMFC applications. However, the ALD catalyst produced on unmodified carbon performed better than the commercial catalyst, which illustrates the power of ALD on appropriate catalyst supports.

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