Relation between Chemical Composition or Antioxidant Activity and Antihypertensive Activity for Six Essential Oils

Six essential oils (EOs), Juniperus phoenicea (leaves and berries), Thymus capitatus, Lauris nobilis, Melaleuca armillaris, and Eucalyptus gracilis, were screened for their antioxidant and antihypertensive activity as well as their chemical compositions. We identified and quantified 24 compounds (representing 99.8% of total oil) for J. phoenicea leaves, 14 compounds (representing 98.8% of total oil) for J. phoenicea berries, 11 compounds (representing 99.6% of total oil) for T. capitatus, 32 compounds (representing 98.9% of total oil) for L. nobilis, 32 compounds (representing 98.7% of total oil) for M. armillaris, and 26 compounds (representing 99.3% of total oil) for E. gracilis. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the antioxidant activity was in the range of 0.59 to 2183.6 mg/L, whereas T. capitatus (1.24 ± 0.05 mg/L) gave the best activity in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonate assay. Antihypertensive activity was evaluated by testing the vasorelaxing capacity of EOs on rat aorta precontracted by phenylephrine (10(-6) M). T. capitatus and L. nobilis were most active for an antihypertensive activity (29 ± 3 and 59 ± 2 mg/L, respectively). Correlations between chemical composition or antioxidant activity and/or antihypertensive activity were studied. Significant correlation has been found for antihypertensive activity and p-cymene (R(2) = 0.86), β-elemene (R(2) = 0.90), and β-myrcene (R(2) = 0.76). A good correlation has been found between antihypertensive activity and antioxidant activity by DPPH assay (R(2) = 0.98). Antioxidant activity can contribute to the prevention of the increase of the blood pressure. According to the literature, no study has been reported until now of correlation between antihypertensive activity and antioxidant activity. Natural EOs can find its interest and application in a medicinal area.     

Al matrix composites fabricated by solid-state cold spray deposition:A critical review

Cold spraying(CS),or cold gas dynamic spray(CGDS),is an emerging solid-state powder deposition process,allowing fast and mass production and restoration of metallic components.CS of metal matrix composites(MMCs)has attracted increasing attention from academia and industry over the last decades,especially in the area of Al matrix composites(AMCs),which have demonstrated a high potential for applications in aerospace,automotive,and electronics industries.This article aims to summarize the recent development of CS-processed AMCs in terms of composite powder preparation,deposition pro-cessing,microstructure evolution,mechanical and corrosion properties.Furthermore,this review also reports the relevant research progress with the focus on post-treatments of the AMCs for CS additive manufacturing applications including heat treatment,hot rolling,and friction stir processing.Finally,the challenges and perspectives on the fabrication of advanced AMCs by CS are addressed.     

Study of the elaboration of a practical weldability window in magnetic pulse welding

This work investigates the elaboration of a weldability window of an aluminium alloy 6060T6 tubular assembly welded by magnetic pulse welding. A destructive test is used to characterize the weld quality. The fractographic analysis of the fracture surface combined with the analysis of the macrographic section of the welded joint allows characterizing two typical weld cases: a potentially permanent weld enabling to undergo plastic deformation and a weld with interfacial discontinuous voids. The presentation of the weld variance in a charging voltage–air gap width diagram gives an operative welding range. The analysis of the impact velocity isovalues in this diagram allows understanding the shape of the weldability window which is potentially convex. The measurement of the wave height at the interface of the welded joint corroborates the qualitative weldability window.     

High deposition efficiency and delamination issues during high-pressure cold spraying metallization of PEEK using spherical copper powders

The International Journal of Advanced Manufacturing Technology - Achieving high deposition efficiency (DE) is a current challenge of cold spraying metallization of polymers for developing surface...     

Contact conditions on nugget development during resistance spot welding of Zn coated steel sheets using rounded tip electrodes

This paper investigates the influence of coating on the nugget development during resistance spot welding of Zn coated steel sheets using rounded tip electrodes. The study relies on an experimental observation of zinc behaviour coupled with a numerical Electro-Thermo-Metallurgical–Mechanical analysis. The electro-thermal contact surface enlargement due to zinc ejection at sheet/sheet and electrode/sheet interfaces is found to have a negligible effect on the nugget development. The numerical analysis shows that the dispersion on the efficient weld size, attributable to the zinc effect, is below 10%.