Water based electrolyzers offer a promising approach for generating hydrogen gas for renewable energy storage. 3M's nanostructured thin film (NSTF) catalyst technology platform has been shown to significantly reduce many of the performance, cost and durability barriers standing in the way of H 2 /air PEM fuel cells for vehicles. In this paper we describe results from the first evaluations of low loaded NSTF catalysts in H 2 /O 2 electrolyzers at Proton OnSite and Giner, Inc. Over two dozen membrane electrode assemblies comprising nine different NSTF catalyst types were tested in 11 short stack durability tests at Proton OnSite and 14 performance tests in 50 cm 2 single cells at Giner Electrochemical Systems. NSTF catalyst alloys of Pt 68 Co 29 Mn 3 , Pt 50 Ir 50 and Pt 50 Ir 25 Ru 25 , with Pt loadings in the range of 0.1 to 0.2 mg/cm 2 , were investigated for beginning-of-life performance and durability up to 4000 hours as both electrolyzer cathodes and anodes. Catalyst composition, deposition and process conditions were found to be important for meeting the performance of standard PGM blacks on electrolyzer anodes while using only 10% as much PGM catalyst. Analyses of MEA's after the durability tests by multiple techniques document changes in catalyst alloy composition, loading, crystallite structure and support stability.Pure pressurized hydrogen gas offers a convenient and predictable means for storing and transporting convertible energy from renewable or other energy sources for powering fuel cells for vehicle, portable and back-up power applications. Renewable energy sources such as wind and solar will require large, efficient and versatile energy storage means for load leveling over wide periods of time covering seconds to days for which electrochemical storage means offer many advantages. Regenerative fuel cells and H 2 /O 2 electrolyzers used for energy storage are key examples. Water based electrolyzers with higher heating value voltage efficiencies of 75% are projected to be able to produce H 2 in the $3-$4/kg range, competitive with current gasoline prices, at reasonable electricity costs on the order of $0.05/kW-Hr. [1][2][3][4] Proton exchange membrane (PEM) based water electrolyzers offer a promising pathway to efficient hydrogen production because of a small installation footprint, ease of handling the solid polymer electrolyte and ability to generate high pressure hydrogen with only deionized water and electricity as inputs. Commercial PEM electrolyzer costs based on current technology are excessive due both to low volume (batch) system assembly and high stack component material costs. However, the electrolyzer stacks and their internal components, viz. separator plates, PEM's and catalysts have cost factors that could benefit significantly from the technology improvements that PEM fuel cell development has enabled over the past decade or more. With respect to the electrocatalysts, current commercial PEM electrolyzers use 2 mg/cm 2 or more of precious group metals (PGM) on their anodes (oxygen ev...

The fungal pathogen Histoplasma capsulatum evades the innate and adaptive immune responses and thrives within resting macrophages (Mφ). Cytokines that induce antimicrobial activity such as granulocyte macrophage-colony stimulating factor (GM-CSF) inhibit H. capsulatum growth in Mφ. Conversely, interleukin 4 (IL-4) inhibits the killing of intracellular pathogens. Using inductively coupled plasma mass spectrometry, we examined alterations in metal homeostasis of murine H. capsulatum-infected Mφ infected that were exposed to activating cytokines. Restriction of iron (Fe2+/3+) and zinc (Zn2+) was observed in infected, GM-CSF-treated Mφ compared to infected controls. IL-4 reversed the anti-fungal activity of GM-CSF-activated Mφ and was associated with increased intracellular Zn2+. Chelation of Zn2+ inhibited yeast replication both in the absence and presence of Mφ. Treatment of cells with GM-CSF altered the host Zn2+ binding species profile. These results establish that Zn2+ deprivation may be a host defense mechanism utilized by Mφ.

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This paper describes a comprehensive investigation of particle number concentrations including a multi-method comparison, theoretical modeling, and cellular dosimetry.

Soybean (Glycine Max) plants were grown in soil supplemented with sodium selenite. A comprehensive selenium profile, including total selenium concentration, distribution of high molecular weight selenium and characterization of low molecular weight selenium compounds, is reported for each plant compartment: bean, pod, leaf and root of the Se-enriched soybean plants. Two chromatographic techniques, coupled with inductively coupled plasma mass spectrometry (ICPMS) for specific selenium detection, were employed in this work to analyze extract solutions from the plant compartments. Size-exclusion chromatography revealed that the bean compartment, well-known for its strong ability to make proteins, produced high amounts (82% of total Se) of high molecular weight selenospecies, which may offer additional nutritional value and suggest high potential for studying proteins containing selenium in plants. The pod, leaf and root compartments primarily accumulate low molecular weight selenium species. For each compartment, low molecular weight selenium species (lower than 5 kDa) were characterized by ion-pairing reversed phase HPLC-ICPMS and confirmed by electrospray ionization ion trap mass spectrometry (ESI-ITMS). Selenomethionine and selenocystine are the predominant low molecular weight selenium compounds found in the bean, while inorganic selenium was the major species detected in other plant compartments.

The copper transporter ATP7A has attracted significant attention since the discovery of its gene mutation leading to human Menkes disease. We previously reported that ATP7A is highly expressed in the human vasculature and identified a novel vascular function of ATP7A in modulation of the expression and activity of extracellular superoxide dismutase. We recently identified that ATP7A expression in THP-1 cells (a monocyte/macrophage model cell line) plays a role in the oxidation of low density lipoproteins, indicating that it is necessary to further investigate its expression and function in monocytes/macrophages. In the current study, we demonstrated the protein and mRNA expression of ATP7A in human peripheral blood mononuclear cell (PBMC)-derived macrophages and alveolar macrophages. ATP7A was strongly co-localized with the trans-Golgi apparatus in PBMC-derived macrophages. Intracellular copper, detected by synchrotron X-ray fluorescence microscopy, was found to be distributed to the nucleus and cytoplasm in human THP-1 cells. To confirm the role of endogenous ATP7A in macrophage copper homeostasis, we performed inductively coupled plasma mass spectrometry in murine peritoneal macrophages, which showed markedly increased intracellular copper levels in macrophages isolated from ATP7A-deficient mice versus control mice. Moreover, the role of ATP7A in regulating macrophage responses to dermal wounds was studied by introduction of control and ATP7A-downregulated THP-1 cells into dermal wounds of nude mice. Infiltration of THP-1 cells into the wounded area (detected by expression of human macrophage markers MAC2 and CD68) was reduced in response to downregulation of ATP7A, hinting decreased macrophage accumulation subsequent to dermal wounds. In summary, alongside our previous studies, these findings indicate that human macrophage ATP7A is localized in the trans-Golgi apparatus, regulates intracellular copper levels, and mediates macrophage responses to a dermal wound.

Our previous study found that high-molecular-weight selenium (Se) species make up 82% of the total Se in the bean of Se-enriched soybean plants (Chan et al. 2010, Metallomics, 2(2): p. 147-153). The Se species have been commonly seen in other plants in addition to soybean, but their identities remain unresolved. The present study employs a multi-technique metallomics approach to characterize the proteins containing Se in the beans of Se-enriched soybean plants. Two main categories of proteins, maturation proteins and protease inhibitors, were found in Se-containing high-performance liquid chromatography (HPLC) fractions. The proteins were screened by two-dimensional HPLC-inductively coupled plasma mass spectrometry, size-exclusion chromatography, and anion-exchange chromatography, and the Se-containing fractions were then identified by peptide mapping using HPLC-Chip-electrospray ion trap mass spectrometry. Based on the belief that Se goes into proteins through non-specific incorporation, a new method was designed and applied for the Se-containing peptide identification. The Se-containing peptide KSDQSSSYDDDEYSKPCCDLCMCTRS, part of the sequence of protein Bowman-Birk proteinase isoinhibitor (Glycine max), was found in one of the Se-containing fractions. The nutritional value of the Se-containing proteins in Se-enriched soybeans will be an interesting topic for the future studies.

Owing to recent progress in analytical techniques, metallomics are evolving from detecting distinct trace metals in a defined state to monitor the dynamic changes in the abundance and location of trace metals in vitro and in vivo. Vascular metallomics is an emerging field that studies the role of trace metals in vasculature. This review will introduce common metallomics techniques including atomic absorption spectrometry, inductively coupled plasma-atomic emission spectrometry, inductively coupled plasma-mass spectrometry and X-ray fluorescence spectrometry with a summary table to compare these techniques. Moreover, we will summarize recent research findings that have applied these techniques to human population studies in cardiovascular diseases, with a particular emphasis on the role of copper in these diseases. In order to address the issue of interdisciplinary studies between metallomics and vascular biology, we will review the progress of efforts to understand the role of copper in neovascularization. This recent advance in the metallomics field may be a powerful tool to elucidate the signaling pathways and specific biological functions of these trace metals. Finally, we summarize the evidence to support the notion that copper is a dynamic signaling molecule. As a future direction, vascular metallomics studies may lead to the identification of targets for diagnosis and therapy in cardiovascular disease.