Comparative study of the chemical composition and biological activities of the essential oils of Senecio gallicus from Tunisia.

The essential oils of flowers and remaining parts of the plant Senecio gallicus (Asteraceae), growing wild in Sfax (Tunisia), were obtained by hydrodistillation over a period of two years (2012 and 2013). Their analysis by Gas Chromatography-Mass Spectrometry (GC-MS), led to a total number of 36 components, belonging to different classes of chemical compounds. Oils compositions were characterized by the abundance of monoterpenes hydrocarbons, the major compounds present in flowers for the two years of study were  respectively the sabinene (49.45% and 28.86%), the α-pinene (9.67% and 9.1%), and the β-myrcene (9.88% and 10.97%). These compounds were also dominant in the essential oils of the plant without flowers where they represent (65.34% and 55%) for the sabinene, (4.14% and 7.3%) for α-pinene, and (6.86% and 0%) for β-myrcene. Obtained essential oils were tested for many biological activities and showed a moderate effect against the fungus Trichoderma reesei and bacteria such as Bacillus sp and Staphylococcus aureus. This study of the Senecio gallicus essential oils represents the first one in Tunisia

Study of Structural Stability of a Concrete Gravity Dam Using a Reliability Approach

The safety of dams is a priority at the international level, based on a large amount of data from a dam-reservoir allows analysts to make optimization on its structural stability, the latter is based on the estimation of the probability of failure from the effects of stress and resistance acting on the dam-reservoir system. This investigation is to establish a methodology in order to optimize the safety of a concrete gravity dam in operation by carrying out a risk analysis which includes the identification of the sources of danger in terms of scenarios that can occur due to a failure on the dam-reservoir system on an implication of natural hazards (floods, earthquakes) and technical accidents such as malfunction of a spillway gate, drain valve, drainage system or important silting. Reliability methods provide a basis for the probabilistic assessment of the structural safety of a dam. They make it possible to take into account in a probabilistic context, the uncertainties in the data associated with the calculation parameters used in the justifications of structural stability and make it possible to assess as closely as possible the intrinsic safety of a concrete gravity dam

Reaction de cohalogenation: Synthese d'alpha-methylene-gamma-butyrolactones. Application a la synthese de la botryodiplodine

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 81557 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Comparative study of the chemical composition and biological activities of the essential oils of Senecio gallicus from Tunisia.

The essential oils of flowers and remaining parts of the plant Senecio gallicus (Asteraceae), growing wild in Sfax (Tunisia), were obtained by hydrodistillation over a period of two years (2012 and 2013). Their analysis by Gas Chromatography-Mass Spectrometry (GC-MS), led to a total number of 36 components, belonging to different classes of chemical compounds. Oils compositions were characterized by the abundance of monoterpenes hydrocarbons, the major compounds present in flowers for the two years of study were  respectively the sabinene (49.45% and 28.86%), the α-pinene (9.67% and 9.1%), and the β-myrcene (9.88% and 10.97%). These compounds were also dominant in the essential oils of the plant without flowers where they represent (65.34% and 55%) for the sabinene, (4.14% and 7.3%) for α-pinene, and (6.86% and 0%) for β-myrcene. Obtained essential oils were tested for many biological activities and showed a moderate effect against the fungus Trichoderma reesei and bacteria such as Bacillus sp and Staphylococcus aureus. This study of the Senecio gallicus essential oils represents the first one in Tunisia

Application Reliability Method for Concrete Dams

Probabilistic risk analysis models are used to provide a better understanding of the reliability and structural failure of works, including when calculating the stability of large structures to a major risk in the event of an accident or breakdown. This work is interested in the study of the probability of failure of concrete dams through the application of reliability analysis methods including the methods used in engineering. It is in our case, the use of level 2 methods via the study limit state. Hence, the probability of product failures is estimated by analytical methods of the type first order risk method (FORM) and the second order risk method (SORM). By way of comparison, a level three method was used which generates a full analysis of the problem and involves an integration of the probability density function of random variables extended to the field of security using the Monte Carlo simulation method. Taking into account the change in stress following load combinations: normal, exceptional and extreme acting on the dam, calculation of the results obtained have provided acceptable failure probability values which largely corroborate the theory, in fact, the probability of failure tends to increase with increasing load intensities, thus causing a significant decrease in strength, shear forces then induce a shift that threatens the reliability of the structure by intolerable values of the probability of product failures. Especially, in case the increase of uplift in a hypothetical default of the drainage system

Noise reduction of a horizontal wind turbine using different blade shapes

Investigation of blade tip shape effect on the noise emission from horizontal axis wind turbine is the target of this work. To recognize the flow around blade wind turbine, and to minimize the noise emission especially at the tip; three different tip blade configurations are tested by using the aerodynamic and the aero-acoustic computational methods. Three dimensional flow simulations are carried out with two unsteady CFD simulations; Unsteady Reynolds-averaged Naviere-Stokes (URANS) and Detached Eddy Simulation (DES). These methods are used to calculate the near-field flow around a HAWT of NREL Phase VI small scale model with different tip blade shapes. Ffowcs Williams-Hawkings (FWâH) analogy is used to predict the sound generated from the turbine, and then it is validated and compared with available experimental data for small-scaled model of NREL Phase VI. In general, the comparison confirms a good and acceptable agreement between DES results and the experimental m easured noise results. Moreover, it is shown that a possibility to reduce or minimize the sound pressure level by using a specific tip shape. The results indicated that the usage of a specific tip shape has an important and significant influence on the noise emission in particular at the high frequency range

Synthesis of C3/C1-Substituted Tetrahydroisoquinolines

A broad biological screening of the natural alkaloid N-methylisosalsoline (2) extracted from Hammada scoparia leaves against a panel of human and parasitic proteases revealed an interesting activity profile of 2 towards human 20S proteasome. This outcome suggests that the 1,2,3,4-tetrahydroisoquinoline skeleton may be exploited as a template for the development of novel anticancer agents. In this article, we report the synthesis and chemical characterization of a new series of isosalsoline-type alkaloids (10–11) with variations at N2 and C3 positions with respect to the natural Compound 2, obtained by a synthetic strategy that involves the Bischler-Napieralski cyclization. The substrate for the condensation to the tetrahydroisoquinoline system, i.e., a functionalized β-arylethyl amine, was obtained through an original double reduction of nitroalkene. The synthetic strategy can be directed to the construction of highly substituted and functionalized 1,2,3,4-tetrahydroisoquinolines

7-ketocholesterol and 7β-hydroxycholesterol: in vitro and animal models used to characterize their activities and to identify molecules preventing their toxicity

International audienceOxysterols are molecules derived by the oxidation of cholesterol and can be formed either by auto-oxidation, enzymatically or by both processes. Among the oxysterols formed by auto-oxidation, 7-ketocholesterol and 7beta-hydroxycholesterol are the main forms generated. These oxysterols, formed endogenously and brought in large quantities by certain foods, have major cytotoxic properties. They are powerful inducers of oxidative stress, inducing dysfunction of organelles (mitochondria, lysosomes and peroxisomes) that can cause cell death. These molecules are often identified in increased amounts in common pathological states such as cardiovascular diseases, certain eye conditions, neurodegenerative disorders and inflammatory bowel diseases. To oppose the cytotoxic effects of these molecules, it is important to know their biological activities and the signaling pathways they affect. Numerous cell models of the vascular wall, eye, brain, and digestive tract have been used. Currently, to counter the cytotoxic effects of 7-ketocholesterol and 7beta-hydroxycholesterol, natural molecules and oils, often associated with the Mediterranean diet, as well as synthetic molecules, have proved effective in vitro. Bioremediation approaches and the use of functionalized nanoparticles are also promising. At the moment, invertebrate and vertebrate models are mainly used to evaluate the metabolism and the toxicity of 7-ketocholesterol and 7beta-hydroxycholesterol. The most frequently used models are mice, rats and rabbits. In order to cope with the difficulty of transferring the results obtained in animals to humans, the development of in vitro alternative methods such as organ / body-on-a-chip based on microfluidic technology are hopeful integrative approaches

Protective effects of milk thistle (Sylibum marianum) seed oil and α-tocopherol against 7β-hydroxycholesterol-induced peroxisomal alterations in murine C2C12 myoblasts: Nutritional insights associated with the concept of pexotherapy

International audiencePeroxisomes play an important role in regulating cell metabolism and RedOx homeostasis. Peroxisomal dysfunctions favor oxidative stress and cell death. The ability of 7β-hydroxycholesterol (7β-OHC; 50 μM, 24 h), known to be increased in patients with age-related diseases such as sarcopenia, to trigger oxidative stress, mitochondrial and peroxisomal dysfunction was studied in murine C2C12 myoblasts. The capacity of milk thistle seed oil (MTSO, 100 μg/mL) as well as α-tocopherol (400 µM; reference cytoprotective agent) to counteract the toxic effects of 7β-OHC, mainly at the peroxisomal level were evaluated. The impacts of 7β-OHC, in the presence or absence of MTSO or α-tocopherol, were studied with complementary methods: measurement of cell density and viability, quantification of reactive oxygen species (ROS) production and transmembrane mitochondrial potential (ΔΨm), evaluation of peroxisomal mass as well as topographic, morphologic and functional peroxisomal changes. Our results indicate that 7β-OHC induces a loss of cell viability and a decrease of cell adhesion associated with ROS overproduction, alterations of mitochondrial ultrastructure, a drop of ΔΨm, and several peroxisomal modifications. In the presence of 7β-OHC, comparatively to untreated cells, important quantitative and qualitative peroxisomal modifications were also identified: a) a reduced number of peroxisomes with abnormal sizes and shapes, mainly localized in cytoplasmic vacuoles, were observed; b) the peroxisomal mass was decreased as indicated by lower protein and mRNA levels of the peroxisomal ABCD3 transporter; c) lower mRNA level of Pex5 involved in peroxisomal biogenesis as well as higher mRNA levels of Pex13 and Pex14, involved in peroxisomal biogenesis and/or pexophagy, was found; d) lower levels of ACOX1 and MFP2 enzymes, implicated in peroxisomal β-oxidation, were detected; e) higher levels of very-long-chain fatty acids, which are substrates of peroxisomal β-oxidation, were found. These different cytotoxic effects were strongly attenuated by MTSO, in the same range of order as with α-tocopherol. These findings underline the interest of MTSO and α-tocopherol in the prevention of peroxisomal damages (pexotherapy)