Perovskite With Tunable Active-Sites Oxidation State by High-Valence W for Enhanced Oxygen Evolution Reaction

Perovskite oxides have been established as a promising kind of catalyst for alkaline oxygen evolution reactions (OER), because of their regulated non-precious metal components. However, the surface lattice is amorphous during the reaction, which gradually decreases the intrinsic activity and stability of catalysts. Herein, the precisely control tungsten atoms substituted perovskite oxides (Pr0.5Ba0.5Co1-xWxO3-δ) nanowires were developed by electrostatic spinning. The activity and Tafel slope were both dependent on the W content in a volcano-like fashion, and the optimized Pr0.5Ba0.5Co0.8W0.2O3-δ exhibits both excellent activity and superior stability compared with other reported perovskite oxides. Due to the outermost vacant orbitals of W6+, the electronic structure of cobalt sites could be efficiently optimized. Meanwhile, the stronger W-O bond could also significantly improve the stability of latticed oxide atoms to impede the generation of surface amorphous layers, which shows good application value in alkaline water splitting.

Susceptibility artifacts induced by crowns of different materials with prepared teeth and titanium implants in magnetic resonance imaging

This study aimed to investigate the artifacts induced by crowns composed of different materials with prepared teeth and titanium implants. Resin, metal-ceramic, ceramic and zirconia crowns were fabricated and placed onto the prepared teeth on a human cadaver head or titanium implants with prosthesis abutments on a dry human mandible. The samples were scanned on a 1.5 T MRI apparatus, and artifact areas were defined as the signal intensity and signal loss adjacent to the prosthesis and measured by a threshold tool with ImageJ2x. Data were analyzed using SPSS 22.0. Resin, ceramic, zirconia, and precious metal-ceramic crowns barely produced artifacts on the cadaver skull (p > 0.999). By contrast, pure Ti and nonprecious metal-ceramic crowns created significant artifacts (p < 0.001). The average artifacts reduction of double Au-Pt and Ag-Pd metal-ceramic crowns combined with titanium implants and abutments was 79.49 mm2 (p < 0.001) and 74.17 mm2 (p < 0.001) respectively, while artifact areas were increased in double Co-Cr and Ni–Cr metal-ceramic crowns by 150.10 mm2 (p < 0.001) and 175.50 mm2 (p < 0.001) respectively. Zirconia, ceramic and precious metal-ceramic crowns induce less MRI artifacts after tooth preparation while precious metal-ceramic crowns alleviate artifacts in combination with titanium implants.

Boosting Nitrate Electroreduction to Ammonia on NbOx via Constructing Oxygen Vacancies

We have synthesized NbOx with oxygen vacancies (OVs) and conducted the first work for nitrate electroreduction to NH3 over Nb oxides. It was a robust non-precious metal catalyst for NH3...

Atomically dispersed Mn-N4 electrocatalyst with high oxygen reduction reaction catalytic activity from metal organic framework ZIF-8 by minimal water assisted mechanochemical synthesis

Developing efficient and stable non-precious metal (NPM) oxygen reduction reaction (ORR) catalyst in an environmentally benign and economically affordable way is highly desired but remains challenging. Manganese and nitrogen co-doped...

Size-Dependent Selectivity of Iron-Based Electrocatalysts for electrochemical CO2 reduction

Applying non-precious metal catalysts to electrocatalytic CO2 reduction (CO2RR) to CO efficiently, rather than gold-based nanomaterials, is of practical significance. Here, we adopt zeolitic imidazolate frameworks (ZIFs) to assist the...

The Cultural Messages of Pyramid House in Palembang

Pyramid House in Palembang is one of the works of art that is still very interesting to be researched today. The problem raised in this study aims to analyze the cultural message of the Pyramid House in Palembang. The method used is a qualitative method with a case study research design. The data collection techniques include observation, interviews, and document study. The results showed that in the manufacture of the Pyramid house, the main construction of traditional buildings used wood construction and a stilt system. The foundation used the construction of piles, the walls used boards, the roof used a leaf or shingle roof. The core parts consisted of the roof of the house, the door, the window, the stairs, and the floor of the house. In general, the typical architectural form of the Pyramid House, namely, the roof was shaped like a severed pyramid. Besides, the uniqueness of the house located in its multi-storey shape (kijing) and the walls were made of wood shaped like planks. Then related to the house name Pyramid, it contained two special meanings, namely, Five and Gold. The word five means the number five, while gold means the precious metal of great value. This is also a symbol of the function of the Pyramid house.