No abstract

No abstract

Spirulina (Artrhospira platensis) is rich in chlorophylls (CH) and is used as a potential natural additive in the food industry. In this study, the CH content was extracted from spirulina powder after ultrasound treatment. Microcapsules were then prepared at different ratios of gum Arabic (GA) and whey protein isolate (WPI) through freeze-drying to improve the chemical stability of CH. As a result, a* and C* values of the microcapsules prepared from GA:WPI ratios (3:7) were −8.94 ± 0.05 and 15.44 ± 0.08, respectively. The GA fraction increased from 1 to 9, and encapsulation efficiency (EE) of microcapsules also increased by 9.62%. Moreover, the absorption peaks of CH at 2927 and 1626 cm−1 in microcapsules emerged as a redshift detected by FT-IR. From SEM images, the morphology of microcapsules changed from broken glassy to irregular porous flake-like structures when the GA ratio increased. In addition, the coated microcapsules (GA:WPI = 3:7) showed the highest DPPH free radical scavenging activity (SADPPH) (56.38 ± 0.19) due to low moisture content and better chemical stability through thermogravimetric analysis (TGA). Conclusively, GA and WPI coacervates as the wall material may improve the stability of CH extracted from spirulina.

No abstract

Ultra-high-voltage transmission line is prone to severely aeolian vibration, especially for the large crossing span. However, few studies were conducted previously, as a result of high nonlinearity and complexity of the bundled conductor aeolian vibration system. This article introduces the analytical models of conductor and damping devices first, to get the key factors for aeolian vibration and to direct the experimental study based on the energy balance principal. Second, the self-damping characteristics of single sub-conductor and energy dissipation power of vibration damper are tested in the laboratory. Third, two aeolian vibration schemes, the first one with vibration dampers only and the second one with both vibration dampers and damping wires, are proposed and evaluated experimentally on the single sub-conductor and then on the eight-bundle test spans. It is found that the concerned conductor has excellent damping effect at highfrequency range and that both of the two schemes show satisfactory aeolian vibration suppression result, but the second one is recommended for its good long-term service performance. This study provides useful reference for aeolian vibration suppression of ultra-high-voltage lines, to avoid fatigue failures of components induced by aeolian vibration and to improve the mechanical security of transmission lines.