No abstract

The microenvironment of the developing follicle is critical to the acquisition of oocyte developmental competence, which is influenced by several factors including follicle size and season. The aim of this study was to characterise the metabolomic signatures of porcine follicular fluid (FF) collected from good and poor follicular environments, using high-resolution proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy. Sow ovaries were collected at slaughter, 4 days after weaning, in summer and winter. The contents of small (3-4 mm) and large (5-8 mm) diameter follicles were aspirated and pooled separately for each ovary pair. Groups classified as summer-small (nZ8), summer-large (nZ15), winter-small (nZ9) and winter-large (nZ15) were analysed by 1 H-NMR spectroscopy.The concentrations of 11 metabolites differed due to follicle size alone (P!0.05), including glucose, lactate, hypoxanthine and five amino acids. The concentrations of all these metabolites, except for glucose, were lower in large FF compared with small FF. Significant interaction effects of follicle size and season were found for the concentrations of glutamate, glycine, N-acetyl groups and uridine. Succinate was the only metabolite that differed in concentration due to season alone (P!0.05). The FF levels of progesterone, androstenedione and oestradiol were correlated with the concentrations of most of the metabolites examined. The results indicate that there is a distinct shift in follicular glucose metabolism as follicles increase in diameter and suggest that follicular cells may be more vulnerable to oxidative stress during the summer months. Our findings demonstrate the power of 1 H-NMR spectroscopy to expand our understanding of the dynamic and complex microenvironment of the developing follicle.

Recent progress in the performance of intermediate temperature (500–600°C) protonic ceramic fuel cells (PCFCs) has demonstrated both fuel flexibility and increasing power density that approach commercial application requirements. Under the U.S. DOE ARPA-E REBELS program, the Colorado School of Mines (Mines), in collaboration with Fuel Cell Energy (FCE), is developing durable, kW-scale PCFC stacks and system concepts. Results from cell scale-up efforts are reviewed. Several cells have been tested for over 6,000 hours, and we demonstrate excellent performance and exceptional durability (<1.5%/1,000 hours in most cases) across all fuels without any modifications in the cell composition or architecture. The success of scale-up efforts towards commercially viable, kW-scale cell platforms is given, inclusive of short stack test results. System-level work shows that trade-offs between lower cell power densities (due to lower operating temperature), lower-cost materials, manufacturing processes, and balance-of-stack components exist which can offer competitive advantage for PCFCs in various stationary power applications.

The behavior of individual positive and negative electrodes of the sintered‐plate nickel‐cadmium battery system in the presence of foreign ions in KOH solutions has been examined. Carbonate choke: The variation of electrochemical capacity as a function of carbonate contamination of the electrolyte, temperature, and current density was measured for both positive and negative electrodes. The effect of carbonate on the negative cadmium electrode is much greater than on the positive. The general mechanism and the role of intermediate complexes are discussed. Nitrate shuttle: Self‐discharge occurs in cells containing nitrate, as a result of reduction of NO3− to NO2− at the cadmium electrode with subsequent reoxidation to NO3− at the nickel hydroxide electrode. Cations on the positive: Addition of Li+, Ag+ Sb+3, Al+3, and As+3 to the electrolyte had effects on capacity and on charge‐retention of well‐formed nickel hydroxide positive electrodes. Lithium promoted the highest average oxidation, particularly at high temperatures (55°C). Arsenic was the best inhibitor of loss of charge. Possible mechanisms are discussed.

This paper develops and discusses a two-dimensional, axisymmetric, computational model that predicts the coupled chemo-thermoinduced stresses associated with a protonic-ceramic fuel cell (PCFC) in a button-cell configuration. The cell is structurally supported on a porous composite Ni-BZY20 anode, with a 20-μm dense BZY20 electrolyte membrane, and a 20-μm porous composite cathode. BZY20 (BaZr 0.8 Y 0.2 O 3−δ ) is a doped perovskite that is dominantly a proton conductor, but supports three mobile charged defects (protons, oxygen vacancies, and small polarons). Lattice-scale strain associated with defect concentrations and temperature manifests itself as a macroscopic stress. The model first evaluates thermally induced stresses that result from large temperature differences during membrane-electrode-assembly fabrication. The model is also applied to evaluate the coupled effects of chemo-thermo-mechanical stresses in the operating fuel cell. Sensitivity analysis is used to characterize the effects of electrochemical and mechanical properties, as well as cell architecture.