6,7,4′-Trihydroxyisoflavone from Doenjang inhibits lipid accumulation

Doenjang is a unique traditional Korean fermented soybean paste. 6,7,4′-Trihydroxyisoflavone was identified from traditional Korean fermented Doenjang. The four products isolated from 100 g Korean Doenjang using acetonitrile and methanol (70/30, v/v) was identified as daidzein, genistein, glycitein and 6,7,4′-trihydroxyisoflavone. The products were structurally elucidated by GC–MS and ¹H NMR analysis. 6,7,4′-Trihydroxyisoflavone was evaluated for antioxidant activity against the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging and superoxide radical scavenging activity. Among four products isolated, 6,7,4′-trihydroxyisoflavone had remarkable antioxidant activity with IC₅₀ values of 31.5 μM, 50.0 μM, respectively. Furthermore, 6,7,4′-trihydroxyisoflavone was found to inhibit fat droplet formation triglyceride accumulation in 3T3-L1 adipocytes. Accordingly, 6,7,4′-trihydroxyisoflavone compound is of growing scientific interest due to its attractive biological properties.     

A 2-dof gravity compensator with bevel gears

This paper presents a 2-dof gravity compensator used for roll-pitch rotations, which are often applied to the shoulder joint of a service or humanoid robot. The 2-dof gravity compensator is comprised of two 1-dof gravity compensators and a bevel differential. The rollpitch rotations are decoupled into two rotations on the moving link by the bevel differential; the two 1-dof gravity compensators are applied to the two rotations. The spring coefficients are determined through energy and torque analyses in order to achieve complete static balancing. The experiment results indicate that the proposed gravity compensator effectively counterbalances the gravitational torques and can also be operated in the hemispherical work space.     

Highly sensitive H2S gas sensors based on CuO-coated ZnSnO3 nanorods synthesized by thermal evaporation

ZnSnO₃ one-dimensional (1D) nanostrutures were synthesized by thermal evaporation. The morphology, crystal structure and sensing properties of the CuO-coated ZnSnO₃ nanostructures to H₂S gas at 100 °C were examined. Transmission electron microscopy and X-ray diffraction revealed both the ZnSnO₃ nanorods and CuO nanoparticles to be single crystals. The diameters of the CuO nanoparticles on the nanorods ranged from a few to a few tens of nanometers. The gas sensors fabricated from multiple networked CuO-coated ZnSnO₃ nanorods exhibited enhanced electrical responses to H₂S gas compared to the uncoated ZnSnO₃ nanorod sensors, showing 61.7-, 49.9-, and 31.3-fold improvement at H₂S concentrations of 25, 50, and 100 ppm, respectively. The response time of the nanorod sensor to H₂S gas was reduced by the CuO coating but the recovery time was similar. The mechanism for the enhanced H₂S gas sensing properties of ZnSnO₃ nanorods by the CuO coating is discussed.     

Densification of silicon dioxide formed by plasma-enhanced atomic layer deposition on 4H-silicon carbide using argon post-deposition annealing

Post-deposition annealing (PDA) was used to improve gate oxide physical and electrical properties. Deposition was accomplished by plasma-enhanced atomic layer deposition (PEALD). We investigated the densification silicon dioxide (SiO₂) formed by PEALD on 4H-silicon carbide (SiC) using PDA without oxidation and nitridation. PDA was conducted at 400–1200?°C in argon (Ar) ambient. The thickness of the SiO₂ was reduced by up to 13.5% after Ar PDA at 1000?°C. As the temperature of the Ar PDA increased, the etching rate of SiO₂ decreased. At temperatures greater than 1000?°C, the SiO₂ etching rate was low compared with that of thermal SiO₂. After PDA, the SiO₂/4H-SiC interface was smoother than that of thermal SiO₂/4H-SiC. The current density versus oxide field and capacitance versus voltage of the SiO₂/4H-SiC metal oxide semiconductor (MOS) capacitors were measured. Sufficient densification of SiO₂ formed by PEALD on 4H-SiC was obtained using Ar PDA at 1200?°C.