Aide à la conception optimale d'une section de fuselage d'avion entièrement composite

International audienceUsing composite materials to build aircraft structures allows minimizing theweight. It also presents new parameters that can be optimized. The finite element modellingof a barrel with several openings is presented. This study exposes the influence of severalfactors on the critical buckling load and determines the best type of conception in terms ofweight.L’utilisation de matériaux composites pour concevoir un fuselage ouvre de nombreuses possibilités et permet un allègement notable. La modélisation par éléments finis d’un barrel percé d’ouvertures est menée. L’étude de l’influence de plusieurs paramètres est proposée afin de déterminer le type de conception répondant au critère de stabilité au flambage tout en assurant un poids minimal

Protective effects of ethyl acetate fraction of Lawsonia inermis fruits extract against carbon tetrachloride-induced oxidative damage in rat liver

This study aimed to investigate the antioxidant properties of different fractions obtained from the fruits of Lawsonia inermis, a widely used medicinal plant, against carbon tetrachloride (CCl4)-induced oxidative stress in rat liver. The results show that several fractions obtained from L. inermis fruits possessed important antioxidant activity. Among them, the ethyl acetate (EA) fraction showed the highest antioxidant activity. Then, EA fraction was selected for the purification of potential antioxidant compounds. The hepatoprotective effects of EA fraction and its most active constituent, gallic acid (GA), were evaluated against CCl4-induced hepatotoxicity in rats. CCl4 induced oxidative stress by a significant rise in serum marker enzymes. However, pretreatment of rats with EA fraction of fruits of L. inermis at a dose of 250 mg kg-1 body weight and GA significantly lowered some serum biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase) in treated rats. A significant reduction in hepatic thiobarbituric acid reactive substances and an increase in antioxidant enzymes namely superoxide dismutase, catalase, and glutathione peroxidase by treatment with plant extract and GA, against CCl4-treated rats, were observed. Histopathological examinations showed extensive liver injuries, characterized by extensive hepatocellular necrosis, vacuolization, and inflammatory cell infiltration. This potential antioxidant activity is comparable to those of the major purified antioxidant compound, GA. Based on these results, it was observed that fruits of L. inermis protect liver from oxidative stress induced by CCl4 and thus help in evaluation of traditional claim on this plant.Tunisian Ministry of Higher Educatio

Protective effects of ethyl acetate fraction of Lawsonia inermis fruits extract against carbon tetrachloride-induced oxidative damage in rat liver

International audienceThis study aimed to investigate the antioxidant properties of different fractions obtained from the fruits of Lawsonia inermis, a widely used medicinal plant, against carbon tetrachloride (CCl 4 )-induced oxidative stress in rat liver. The results show that several fractions obtained from L. inermis fruits possessed important antioxidant activity. Among them, the ethyl acetate (EA) fraction showed the highest antioxidant activity. Then, EA fraction was selected for the purification of potential antioxidant compounds. The hepatoprotective effects of EA fraction and its most active constituent, gallic acid (GA), were evaluated against CCl 4 -induced hepatotoxicity in rats. CCl 4 induced oxidative stress by a significant rise in serum marker enzymes. However, pretreatment of rats with EA fraction of fruits of L. inermis at a dose of 250 mg kg −1 body weight and GA significantly lowered some serum biochemical parameters (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase) in treated rats. A significant reduction in hepatic thiobarbituric acid reactive substances and an increase in antioxidant enzymes namely superoxide dismutase, catalase, and glutathione peroxidase by treatment with plant extract and GA, against CCl 4 -treated rats, were observed. Histopathological examinations showed extensive liver injuries, characterized by extensive hepatocellular necrosis, vacuolization, and inflammatory cell infiltration. This potential antioxidant activity is comparable to those of the major purified antioxidant compound, GA. Based on these results, it was observed that fruits of L. inermis protect liver from oxidative stress induced by CCl 4 and thus help in evaluation of traditional claim on this plant

<em>STA1</em>, an <em>Arabidopsis</em> pre-mRNA processing factor 6 homolog, is a new player involved in miRNA biogenesis

MicroRNAs (miRNAs) are small regulatory RNAs that have important regulatory roles in numerous developmental and metabolic processes in most eukaryotes. In Arabidopsis, DICER-LIKE1 (DCL1), HYPONASTIC LEAVES 1, SERRATE, HUA ENHANCER1 and HASTY are involved in processing of primary miRNAs (pri-miRNAs) to yield precursor miRNAs (pre-miRNAs) and eventually miRNAs. In addition to these components, mRNA cap-binding proteins, CBP80/ABA HYPERSENSITIVE1 and CBP20, also participate in miRNA biogenesis. Here, we show that STABILIZED1 (STA1), an Arabidopsis pre-mRNA processing factor 6 homolog, is also involved in the biogenesis of miRNAs. Similar to other miRNA biogenesis-defective mutants, sta1-1 accumulated significantly lower levels of mature miRNAs and concurrently higher levels of pri-miRNAs than wild type. The dramatic reductions of mature miRNAs were associated with the accumulation of their target gene transcripts and developmental defects. Furthermore, sta1-1 impaired splicing of intron containing pri-miRNAs and decreased transcript levels of DCL1. These results suggest that STA1 is involved in miRNA biogenesis directly by functioning in pri-miRNA splicing and indirectly by modulating the DCL1 transcript level