Phytic Acid-Based FeCo Bimetallic Metal-Organic Gels for Electrocatalytic Oxygen Evolution Reaction.

Electrocatalysts have been developed to improve the efficiency of gas release for oxygen evolution reaction (OER), and finding a simple and efficient method for efficient electrocatalysts has inspired research enthusiasm. Herein, we report bimetallic metal-organic gels derived from phytic acid (PA) and mixed transition metal ions to explore their performance in electrocatalytic oxygen evolution reaction. PA is a natural phosphorus-rich organic compound, which can be obtained from plant seeds and grains. PA reacts with bimetallic ions (Fe3+ and Co2+ ) in a facile one-pot synthesis under mild conditions to form PA-FeCo bimetallic gels, and the corresponding aerogels are further partially reduced with NaBH4 to improve the electrocatalytic activity. Mixed valence states of Fe(II)/Fe(III) and Co(III)/Co(II) are present in the materials. Excellent OER performance in terms of overpotential (257 mV at 20 mA cm-2 ) and Tafel slope (36 mV dec-1 ) is achieved in an alkaline electrolyte. This reduction method is superior to the pyrolysis method by well maintaining the gel morphology structure. This strategy is conducive to the further improvement of the performance of metal-organic electrocatalysts, and provides guidance for the subsequent application of metal-organic gel electrocatalysts.

[Serum levels and significance of HIF-1α and HIF-2α in healthy Tibetan and Han residents at different altitudes].

OBJECTIVE: To explore the serum levels and significance of hypoxic inducible factor (HIF)-1α and HIF-2α in Tibetan and Han residents living at different altitudes. METHODS: A total of 100 healthy adults of Han in plain (altitude 5 m, group P) and Tibetan and Han at moderate altitude (2260 m, groups M1 & M2) and high altitude (4380 m, groups H1 & H2) (n = 20 each) were selected from June 2010 to August 2010. Venous blood samples were collected in the morning. The serum concentrations of HIF-1α and HIF-2α were measured with enzyme-linked immunosorbent assay (ELISA) to analyze the correlations of HIF-1α and HIF-2α with arterial partial pressure of oxygen (PaO2) and hemoglobin (Hb). RESULTS: The level of HIF-1α in group H2 ( (6.06 ± 1.85) µg/L) was higher than that in groups P ( (4.56 ± 0.85) µg/L, P < 0.05) , M1 ((4.41 ± 1.05) µg/L, P < 0.01) and M2 ( (4.59 ± 1.03) µg/L, P < 0.05) . The level of HIF-1α in group H1 ( (5.27 ± 0.98) µg/L) was higher than that in group M1 (P < 0.05) . The level of HIF-2α in group H2 ((0.83 ± 0.48) µg/L) was higher than that in groups P ((0.33 ± 0.11) µg/L, P < 0.01), M1 ((0.14 ± 0.06 )µg/L, P < 0.01) and M2( (0.24 ± 0.11) µg/L, P < 0.01) . The level of HIF-2α in group M1 was lower than that in groups P (P < 0.01) and M2 (P < 0.01). The level of HIF-2α in group H1((0.18 ± 0.16)µg/L) was lower than that in groups P (P < 0.05) and H2 (P < 0.01) . The levels of HIF-1α and HIF-2α were negatively correlated with PaO2 (r = -0.475, -0.551, both P < 0.01) and positively with Hb in Han groups (r = 0.433, 0.463, all P < 0.01). The levels of HIF-1α and HIF-2α had no correlation with PaO2 in Tibetan groups (r = -0.270, -0.198, both P > 0.05). No correlation existed between HIF-1α and Hb in Tibetan. A positive correlation existed between HIF-2α and Hb in Tibetan (r = 0.325, P < 0.01). CONCLUSIONS: The changes of HIF-1α and HIF-2α vary for Tibetan and Han residents at different altitudes. And the level of HIF-2α is consistent with the change of Hb. As compared with HIF-1α, HIF-2α may play a more important role in regulating Hb.