Electrochemical and Photoelectrochemical Investigation of Water Oxidation with Hematite Electrodes

Atomic layer deposition (ALD) was utilized to deposit uniform thin films of hematite (α-Fe2O3) on transparent conductive substrates for photocatalytic water oxidation studies. Comparison of the oxidation of water to the oxidation of a fast redox shuttle allowed for new insight in determining the rate limiting processes of water oxidation at hematite electrodes. It was found that an additional overpotential is needed to initiate water oxidation compared to the fast redox shuttle. A combination of electrochemical impedance spectroscopy, photoelectrochemical and electrochemical measurements were employed to determine the cause of the additional overpotential. It was found that photogenerated holes initially oxidize the electrode surface under water oxidation conditions, which is attributed to the first step in water oxidation. A critical number of these surface intermediates need to be generated in order for the subsequent hole-transfer steps to proceed. At higher applied potentials, the behavior of the electrode is virtually identical while oxidizing either water or the fast redox shuttle; the slight discrepancy is attributed to a shift in potential associated with Fermi level pinning by the surface states in the absence of a redox shuttle. A water oxidation mechanism is proposed to interpret these results

Atrial natriuretic peptide-induced microalbuminuria is associated with endothelial dysfunction in noncomplicated type 1 diabetes patients.

Item does not contain fulltextBACKGROUND: Microalbuminuria reflects widespread vascular dysfunction in type 1 diabetes mellitus and results from increased glomerular sieving caused by changes in transglomerular pressure and/or permselectivity characteristics of the glomerular basement membrane. Increased tubular reabsorption or degradation of albumin will offset an early increase in albuminuria. We hypothesized that the infusion of atrial natriuretic peptide (ANP) as a tool to increase glomerular permeability might uncover changes in permselectivity in patients with uncomplicated type 1 diabetes. METHODS: We investigated whether these patients were characterized by endothelial and/or vascular dysfunction. We therefore studied 46 normoalbuminuric patients (urinary albumin excretion [UAE] 2 SD of controls) to ANP infusion (mean UAE, 30.3 +/- 1.0 microg/min; 425% +/- 61%) was characterized by a diminished vasodilatory response to ACh (maximal forearm blood flow, 17.2 +/- 2.9 [+563%] versus 26.3 +/- 2.3 mL/min/dL [+800%] in patients with diabetes with a normal albuminuric response; P < 0.05). CONCLUSIONS: In a subgroup of patients with uncomplicated type 1 diabetes, an increase in glomerular permselectivity can be unmasked by the infusion of ANP. These patients are characterized by a diminished vascular response to ACh

Insight into the Selectivity of Isopropanol Conversion at Strontium Titanate (100) Surfaces: A Combination Kinetic and Spectroscopic Study

This work aims to better understand the role of interfacial molecular structure that governs selectivity and activity in heterogeneous catalytic reactions. To address this, a comprehensive study of isopropyl alcohol conversion over an archetypal perovskite material, strontium titanate (SrTiO₃ or STO), was performed with an array of techniques sensitive to orthogonal aspects of the ensuing chemistry. Cubic-shaped STO nanoparticles with only the (100) facet exposed were synthesized and used to study the ensemble kinetic conversion of isopropyl alcohol over the surfaces, which showed selectivity to form acetone, with minor propylene products appearing at elevated temperatures. These results in combination with inelastic neutron scattering measurements provide not only insight into the selectivity and overall activity of the catalysts but also low-frequency vibrational signatures of the adsorbed and reacted species. To complement these measurements, pristine thin films of STO (100) were synthesized and used in combination with vibrational sum frequency generation spectroscopy to extract the absolute molecular orientation of the adsorbed molecules at the interface. It was found that the isopropyl alcohol assumes an orientation where the −CH group points toward the STO surface; this prereaction geometry offers an obvious pathway to produce acetone by abstracting the α proton and, thus, provides a mechanistic explanation of selectivity at STO (100) surfaces. This insight opens up pathways to explore and modify surfaces to tune the activity/selectivity through a molecular level understanding of the reactions at the surface

Orthodox, Humanitarian, and Science-Inspired Belief in Relation to Prejudice Against Jews, Muslims, and Ethnic Minorities: The Content of One's Belief Does Matter

Contains fulltext : 55832.pdf (publisher's version ) (Closed access)In this study, we empirically explored the relation between (a) the content of people's orthodox, humanitarian, and science-inspired beliefs and (b) three measures of prejudice. Using survey data from a representative subsample of indigenous Dutch (n = 582), we found that orthodox, humanitarian, and science-inspired convictions that had different relations with prejudice could be discerned in The Netherlands. Most important, we found that humanitarian convictions could make people show compassion for their fellow human beings and could, thereby, work against the acceptance of prejudice. In contrast, orthodox convictions did not seem to work against the acceptance of prejudice against ethnic minorities, Muslims, and Jews. Science-inspired convictions were found to be unrelated to prejudice