Preservation du concentre de tomate par un agent antifongique (Huile essentielle du citron)

Les huiles essentielles ont des molécules naturelles considérées comme antioxydants, antimicrobiens servant comme conservateur naturel pour préserver l’aliment des différentes altérations. Cette étude a pour objectifs de valoriser les écorces de Citrus limon de la variété « Euréka » par extraction de ses huiles essentielles, d’évaluer in vitro l’activité antifongique de ces huiles extraites par deux modes: hydrodistillation (HEH) et pression à froid (HEP), et enfin les appliquer au concentré de tomate. Le rendement moyen en huile essentielle extraite par hydrodistillation est de 2,20±0,773% et celui de l’huile extraite par pression à froid est de 0,87±0,025%. La composition de ces huiles a été analysée par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC/MS). Les résultats nous ont permis d’identifier 30 constituants représentant 97,81% et 97,42% de l’huile essentielle totale HEH et de celle de HEP, respectivement. Les composants principaux étaient le limonène suivi du α-pinèneet de γ-terpinène. Le test de l’activité antifongique des huiles essentielles du citron a été réalisé par la méthode des aromatogrammes et a montré que cette huile possède une activité antifongique plus au moins intéressante. Les concentrations minimales inhibitrices (CMI) ont été estimées par la méthode de dilution d’agar. Les souches fongiques telles que Aspergillus terreus, Aspergillus niger, Aspergillus flavus, Trichoderma  longibrachiatum, Fusarium oxysporum et Fusarium culmorum ont révélé une nette sensibilité vis-à-vis des huiles extraites avec des CMIs qui varient entre 350 et 600 μg.ml-1 pour HEH et entre 180 à 500μg.ml-1 pour HEP. Ces résultats ont été confirmés par l’application des huiles HEH et HEP au concentré de tomate qui a présenté une meilleure résistance à la contamination fongique par rapport au témoin (sans huiles essentielles) révélant une modification de lacouleur (le rouge vire vers le marron). L’application de ces huiles essentiellesau concentré de tomate nous a permis de déduire que cette huile limite l’altération par les moisissures et le conserve un peu longtemps (deux mois). Essential oils have natural molecules considered as antioxidants, and antimicrobial substances serving as natural preservatives used to preserve the food from various alterations. The objectives of this study were to enhance the use of Citrus limonpeel of the "Eureka" variety by extracting its essential oils, to evaluate in vitro the antifungal activity of these oils extracted by two methods: hydrodistillation (HEH) and cold pressure (HEP), and finally apply them to the tomato concentrate in order to see their effect on fungi (molds). The average yield of essential oil extracted by hydrodistillation is 2.20 ± 0.773% and that of the oil extracted by cold pressing is 0.87 ± 0.025%. The composition of these oils was analyzed by gas chromatography coupled with mass spectrometry (GC / MS). The results allowed us to identify 30 constituents representing 97.81% and 97.42% of the total essential oil HEH and that of HEP, respectively. The main components were limonene followed by α-pinene and γ-terpinene. The test of the antifungal activity of essential oils of lemon has been carried out by the aromatogrammes method; it showed that this oil has an antifungal activity. Minimum inhibitory  concentrations (MIC) were estimated by the agar dilution method. The fungal strains (molds) Aspergillus terreus, Aspergillus niger, Aspergillus flavus, Trichoderma longibrachiatum, Fusarium oxysporum and Fusarium culmorum revealed sensitivity to extracted oils with MICs that vary between 350 and 600 μg.ml-1 for HEH and between 180 and 500 μg.ml-1 for HEP. These results were confirmed by the application of HEH and HEP oils to tomato concentrate, which showed better resistance to fungal contamination compared to the control (without essential oils) revealing a change in color (red turns to brown). The application of these essential oils to tomato concentrate has allowed us to deduce that this oil limits the damage caused by molds and keeps it safe for about two months

Neurosurgical management of anterior meningo-encephaloceles about 60 cases

Anterior meningo-encephaloceles (AME) are congenital malformations characterized by herniation of brain tissue and meninges through a defect in the cranium, in frontal, orbital, nasal and ethmoidal regions. The management of this complex congenital malformation is controversial according to whether use, an intracranial, extra-cranial or combined approach. This is the first largest series published in Africa, in which we present our experience in the operative management of AME; we share our recommendation in technical consideration for surgical approach with review of the literature. All patients beneficed of neuro-radiological investigations including Plan X rays, Spiral Three dimensional CT scan and MRI. Ophthalmologic and maxillo-facial evaluations were done in all the cases. MEA are surgically approached in various ways, mainly on the basis of its location and type, by cranio-facial approach in one-step, or in two stages by intracranial approach followed by facial approach, only by cranial approach or facial approach. The surgical results were evaluated in the follow up on the basis of disappearance of cranio-facial tumefaction with correction of hypertelorism. 60 children with AME were treated in our department between January 1992 and December 2012. The mean age at time of surgery was 14 months (20 days to 18 years) with slight men predominance (28 females/32 males). Cranio-facial team operated 21 patients, 16 were operated in two stages by intracranial approach followed by facial approach, 20 cases beneficed the neurosurgical approach and three only the facial approach Some post operative complications were observed: 2 cases of post operative hydrocephalus underwent shunt; CSF fistulas in three cases cured by spinal drainage, one death due to per operative hypothermia, 3 cases of recurrence how needed second surgery. After mean follow up for 80 months (1 year to 19 years) theses techniques permitted a good cosmetics results in 42 cases, average cosmetics results in 8 cases, poor results in 5 cases and worse cosmetics results in 4 cases, The AME are rare conditions we used the multiples approach first intracranial approach followed by facial approach, but after 1998 we used one-step correction by combined approach, only cranial approach when needed or facial correction

Methidathion-induced hematological, biochemical and hepatohistological alterations in rat: Ameliorative effects of selenium and zinc

The aim of this study was to determine the effect of a sub-acute 4-week exposure to methidathion (MD) on the hematological system and hepatic integrity of rats. We also assessed whether co-administration of micronutrients such as selenium (Se) and zinc (Zn) prevented MD-induced hepatic damage. Rats were randomly divided into four groups of six each: the first group served as a control which received standard diet, the second group received both Se (0.5mg/kg of diet) and Zn (0.227 g/l drinking water), the third group received only MD (5 mg/kg b.w. by gavage using corn oil as a vehicle), and the fourth group received MD and combined selenium and zinc. After four weeks, exposure to MD induced a significant increase in plasmatic activities of AST, ALT, ALP, LDH, and liver malondialdehyde level. In contrast, reduced glutathione level (GSH), and the activities of catalase (CAT), superoxide dismutase (SOD), and the glutathione peroxidase (GPx) content of hepatic tissue decreased significantly. Moreover, treatment with Se and Zn in MD-treated rats maintained all the biochemical parameters cited above. In conclusion, the obtained results indicate the ability of Se and Zn to attenuate the MD-induced liver and erythrocytes oxidative damage.Key words: Biochemical studies, liver, methidathion, oxidative stress, rat, selenium, zinc

The remnant of SN1987A revealed at (sub-)mm wavelengths

Context: Supernova 1987A (SN1987A) exploded in the Large Magellanic Cloud (LMC). Its proximity and rapid evolution makes it a unique case study of the early phases in the development of a supernova remnant. One particular aspect of interest is the possible formation of dust in SN1987A, as SNe could contribute significantly to the dust seen at high redshifts. Aims: We explore the properties of SN1987A and its circumburst medium as seen at mm and sub-mm wavelengths, bridging the gap between extant radio and infrared (IR) observations of respectively the synchrotron and dust emission. Methods: SN1987A was observed with the Australia Telescope Compact Array (ATCA) at 3.2 mm in July 2005, and with the Atacama Pathfinder EXperiment (APEX) at 0.87 mm in May 2007. We present the images and brightness measurements of SN1987A at these wavelengths for the first time. Results: SN1987A is detected as an unresolved point source of 11.2 +/- 2.0 mJy at 3.2 mm (5" beam) and 21 +/- 4 mJy at 0.87 mm (18" beam). These flux densities are in perfect agreement with extrapolations of the powerlaw radio spectrum and modified-blackbody dust emission, respectively. This places limits on the presence of free-free emission, which is similar to the expected free-free emission from the ionized ejecta from SN1987A. Adjacent, fainter emission is observed at 0.87 mm extending ~0.5' towards the south-west. This could be the impact of the supernova progenitor's wind when it was still a red supergiant upon a dense medium. Conclusions: We have established a continuous spectral energy distribution for the emission from SN1987A and its immediate surroundings, linking the IR and radio data. This places limits on the contribution from ionized plasma. Our sub-mm image reveals complexity in the distribution of cold dust surrounding SN1987A, but leaves room for freshly synthesized dust in the SN ejecta.Comment: Accepted for publication in Astronomy and Astrophysics Letters on 28 April 2011. A better quality figure 1 can be had from http://www.astro.keele.ac.uk/~jacco/research/SN1987A087mm.ep

Efficient hole-transporting layer MoO3:CuI deposited by co-evaporation in organic photovoltaic cells

In order to improve hole collection at the interface anode/electron donor in organic photovoltaic cells, it is necessary to insert a hole transporting layer. CuI was shown to be a very efficient hole transporting layer. However, its tendency to be quite rough tends to induce leakage currents and it is necessary to use a very slow deposition rate for CuI to avoid such negative effect. Herein, we show that the co-deposition of MoO3 and CuI avoids this difficulty and allows deposition of a homogeneous efficient hole-collecting layer at an acceptable deposition rate. Via an XPS study, we show that blending MoO3:CuI improves the hole collection efficiency through an increase of the gap state density. This increase is due to the formation of Mo5þ following interaction between MoO3 and CuI. Not only does the co-evaporation process allow for decreasing significantly the deposition time of the hole transporting layer, but also it increases the efficiency of the device based on the planar heterojunction, CuPc/C60

MoO3/Ag/MoO3 anode in organic photovoltaic cells: Influence of the presence of a CuI buffer layer between the anode and the electron donor

MoO3/Ag/MoO3 (MAM) multilayer structures (layers thickness 20 nm/10nm/35 nm) are used as anode in CuPc/C60/Alq3/Al organic photovoltaic cells. The averaged transmittance (400 nm-800 nm) of these MoO3/Ag/MoO3 multilayer structures is 70%62% and their sheet resistance is 3.5 61.0 X/sq. When these multilayer structures are used as anode, the power conversion efficiency of the MoO3/Ag/MoO3/CuPc/C60/Alq3/Al cells is around 1%, this efficiency is increased of 50% when a thin CuI film (3 nm) is introduced at the interface between the anode and the organic film. This improvement is attributed to the templating effect of CuI on the CuPc molecule

Effects of e−e+νee^- e^+ \nu_e Decays of Tau Neutrinos Near A Supernova

We revisit the constraints implied by SN 1987 A observations on the decay rate of a multi-MeV $\nu_\tau$ decaying into the visible channel $\nu_\tau \rightarrow e^+ e^- \nu_e$, if its lifetime is more than 10 {\it sec.}. We discuss its implication for the minimal left-right symmetric model with see-saw mechanism for neutrino masses. We also speculate on the possible formation of a ``giant Capacitor" in intergalactic space due to the decay of "neutronization" $\nu_\tau$'s and spin allignment possibility in the supernova.Comment: 29 Pages, Tex file, UMDHEP 94-4

First Stars. I. Evolution without mass loss

The first generation of stars was formed from primordial gas. Numerical simulations suggest that the first stars were predominantly very massive, with typical masses M > 100 Mo. These stars were responsible for the reionization of the universe, the initial enrichment of the intergalactic medium with heavy elements, and other cosmological consequences. In this work, we study the structure of Zero Age Main Sequence stars for a wide mass and metallicity range and the evolution of 100, 150, 200, 250 and 300 Mo galactic and pregalactic Pop III very massive stars without mass loss, with metallicity Z=10E-6 and 10E-9, respectively. Using a stellar evolution code, a system of 10 equations together with boundary conditions are solved simultaneously. For the change of chemical composition, which determines the evolution of a star, a diffusion treatment for convection and semiconvection is used. A set of 30 nuclear reactions are solved simultaneously with the stellar structure and evolution equations. Several results on the main sequence, and during the hydrogen and helium burning phases, are described. Low metallicity massive stars are hotter and more compact and luminous than their metal enriched counterparts. Due to their high temperatures, pregalactic stars activate sooner the triple alpha reaction self-producing their own heavy elements. Both galactic and pregalactic stars are radiation pressure dominated and evolve below the Eddington luminosity limit with short lifetimes. The physical characteristics of the first stars have an important influence in predictions of the ionizing photon yields from the first luminous objects; also they develop large convective cores with important helium core masses which are important for explosion calculations.Comment: 17 pages, 24 figures, 2 table

Two Type Ic supernovae in low-metallicity, dwarf galaxies: diversity of explosions

We present BVRI photometry and optical spectroscopy of two Type Ic supernovae SN 2007bg and SN 2007bi discovered in wide-field, non-targeted surveys and associated with sub-luminous blue dwarf galaxies. Neither SNe 2007bg nor 2007bi were found in association with an observed GRB, but are found to inhabit similar low-metallicity environments as GRB associated supernovae. The radio-bright SN 2007bg is hosted by an extremely sub-luminous galaxy of magnitude MB = -12.4+/-0.6 mag with an estimated oxygen abundance of 12+log(O/H) = 8.18+/-0.17. The lightcurve of SN 2007bg displays one of the fastest post-maximum decline rates of all broad-lined Type Ic supernovae known to date and, when combined with its high expansion velocities, a high kinetic energy to ejected mass ratio (E_K/Mej ~ 2.7). We show that SN 2007bi is possibly the most luminous Type Ic known, reaching a peak magnitude of MR ~ 21.3 mag and displays a remarkably slow decline, following the radioactive decay rate of 56Co to 56Fe throughout the course of its observed lifetime. From a simple model of the bolometric light curve of SN 2007bi we estimate a total ejected 56Ni mass of M_Ni = 3.5 - 4.5 solar masses, the largest 56Ni mass measured in the ejecta of a supernova to date. There are two models that could explain the high luminosity and large ejected 56Ni mass. One is a pair-instability supernova (PISN) which has been predicted to occur for massive stars at low metallicities. We measure the host galaxy metallicity of SN 2007bi to be 12 + log(O/H) = 8.15+/-0.15 which is somewhat high to be consistent with the PISN model. An alternative is the core-collapse of a C+O star of 20 - 40 solar masses which is the core of a star of originally 50 - 100 solar masses. (Abridged)Comment: Minor changes. 19 pages, 21 Figures. Accepted by A&

Formation of Supermassive Black Holes

Evidence shows that massive black holes reside in most local galaxies. Studies have also established a number of relations between the MBH mass and properties of the host galaxy such as bulge mass and velocity dispersion. These results suggest that central MBHs, while much less massive than the host (~ 0.1%), are linked to the evolution of galactic structure. In hierarchical cosmologies, a single big galaxy today can be traced back to the stage when it was split up in hundreds of smaller components. Did MBH seeds form with the same efficiency in small proto-galaxies, or did their formation had to await the buildup of substantial galaxies with deeper potential wells? I briefly review here some of the physical processes that are conducive to the evolution of the massive black hole population. I will discuss black hole formation processes for `seed' black holes that are likely to place at early cosmic epochs, and possible observational tests of these scenarios.Comment: To appear in The Astronomy and Astrophysics Review. The final publication is available at http://www.springerlink.co