Superior electro-catalytic activity of a heterogeneous bi-metallic [Cu/Co(6mna)₂]_n MOF was established by synergistic effects between conductive [Cu₂(6mna)(6mn)NH₄]_n with 2D (–Cu–S–)_n planes and porous [Co₂(6mna)₂]_n with helical (–Co–S–)_n chains.

A hierarchical urchin-like structure of CoSe₂/CoSeO₃ (denoted as CoSe₂/CoSeO₃-UL) is synthesized by a one-step hydrothermal method and investigated as the electro-catalyst for the counter electrode (CE) of dye-sensitized solar cells (DSSCs).

BackgroundTwo parallel cannulated screws along with an anterior wire to construct a tension band is a popular approach in transverse patellar fractures. However, the optimal screw proximity, either deep or superficial screw placements, remains controversial. Hence, a new concept of the addition of a third screw to form a triangular configuration along with the original two parallel screws was proposed in this study. Therefore, the biomechanical effect of the additional third screw on the stability of the fractured patella was investigated with finite element (FE) simulation.MethodsAn FE knee model including the distal femur, proximal tibia, and fractured patella (type AT/OTA 34-C) was developed in this study. Four different screw configurations, including two parallel cannulated screws with superficial (5-mm proximity) and deep (10-mm proximity) placements and two parallel superficial screws plus a third deep screw, and two parallel deep screws plus a third superficial screw, with or without the anterior wire, were considered for the simulation.ResultsResults indicated that the addition of a third screw increased stability by reducing the dorsal gap opening when two parallel screws were deeply placed, particularly on the fractured patella without an anterior wire. However, the third screw was of little value when two parallel screws were superficially placed. In the existence of two deep parallel screws and the anterior wire, the third screw reduced the gap opening by 23.5% (from 1.15mm to 0.88mm) and 53.6% (from 1.21mm to 0.61mm) in knee flexion 45 degrees and full extension, respectively. Furthermore, in the absence of the anterior wire, the third screw reduced the gap opening by 73.5% (from 2mm to 0.53mm) and 72.2% (from 1.33mm to 0.37mm) in knee flexion 45 degrees and full extension, respectively.ConclusionBased on the results, a third cannulated screw superficially placed (5-mm proximity) is recommended to increase stability and maintain contact of the fractured patella, fixed with two parallel cannulated screws deeply placed (10-mm proximity), particularly when an anterior wire was not used. Furthermore, the third screw deeply placed is not recommended in a fractured patella with two parallel superficial screws.