Si/ZnO heterostructures for efficient diode and water-splitting applications

We have developed thin zinc oxide (ZnO) layers protected highly conductive p-type silicon (Si) electrodes and investigated their diode and photoanode characteristics. ZnO layers have been deposited on the glass as well as p-Si substrates at a temperature of 400 degrees C by pulsed spray pyrolysis method. The crystal structure, surface morphology, and phase purity of the layers along with electrical characteristics of the heterostructures were investigated. Finally, the photocatalytic water oxidation performance of the ZnO/Si structures was studied in an alkaline electrolyte solution (pH = 10). The as-grown devices exhibited excellent diode characteristics with a turn-on voltage of 4.5 V, and applied bias-voltage dependent carrier transport mechanisms. As compared to bare Si, ZnO coated Si-based PEC devices showed good stability and durability along with very low onset potential of 0.07 V versus Ag/AgCl. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved

Oxidatively-mediated in silico epimerization of a highly amyloidogenic segment in the human calcitonin hormone (hCT15-19)

In order to study the effects of peptide exposure to oxidative attack, we chose a model reaction in which the hydroxyl radical discretely abstracts a hydrogen atom from the α-carbon of each residue of a highly amyloidogenic region in the human calcitonin hormone, hCT15-19. Based on a combined Molecular Mechanics / Quantum Mechanics approach, the extended and folded L- and D-configuration and radical intermediate hCT15-19 peptides were optimized to obtain their compactness, secondary structure and relative thermodynamic data. The results suggest that the epimerization of residues is generally an exergonic process that can explain the cumulative nature of molecular aging. Moreover, the configurational inversion induced conformational changes can cause protein dysfunction. The epimerization of the central residue to the D-configuration induced a hairpin structure in hCT15-19, concomitant with a possible oligomerization of human calcitonin into Aβ(1–42)-like amyloid fibrils present in patients suffering from Alzheimer’s disease