La baisse de la densité osseuse au cours des maladies inflammatoires chroniques de l’intestin : prévalence et facteurs de risqué

Introduction: La baisse de la densité minérale osseuse représente la principale manifestation osseuse décrite au cours des maladies inflammatoires chroniques de l'intestin. En Tunisie, très peu d'études ont rapportés sa prévalence et ses facteurs de risque. Le but de ce travail était de déterminer la prévalence de la perte osseuse au cours des maladies inflammatoires chroniques de l'intestin, et rechercher ses facteurs de risque. Méthodes: Patients et méthodes: étude ouverte transversale, réalisée de 2007 jusqu'à 2012. Résultats: 146 cas étaient colligés, dont 105 avaient une maladie de Crohn (71,9%) et 41 avaient une rectocolite hémorragique (28,1%). Il s'agissait de 62 hommes et 84 femmes. L'âge moyen était de 33,18 ans. La perte osseuse était trouvée chez 85 patients (58,2%). Il s'agissait d'une ostéopénie dans 57 cas et d'ostéoporose dans 28 cas. Les facteurs de risque de perte osseuse étaient une activité physique limitée  (p=0,013), un indice de masse corporel '20 kg/m2 (p=0,015), une maladie active (p=0,035), l'étendue de l'atteinte intestinale (p=0,006) et une dose cumulée de corticothérapie dépassant 4,5g de Prednisone (p=0,003). Conclusion: La déminéralisation osseuse est une complication fréquente mais non constante. Ceci justifie un dépistage précoce chez les patients à risque, qui pourront ainsi bénéficier d'un traitement substitutif.Key words: Maladie de Crohn, recto-colite hémorragique, densité minérale osseuse, ostéopénie, ostéoporos

Insecticidal activities of essential oils from some cultivated aromatic plants against Ppodoptera littoralis (Boisd)

Medicinal plant species were tested for their fumigant activity against Spodoptera littoralis third instar larvae. Responses varied according to plant species and parts used. For the present investigation, volatile oils were obtained from: Foeniculum vulgare (flowers and seeds), Coriandrum sativum (seeds), Daucus carota (flowers), Pelargonium graveolens (leaves and flowers), Origanum majorana (leaves and flowers), and Salvia officinalis (leaves). Fumigant activity was observed after 24 hours of exposure. All essential oils were proved to be toxic to the third instar larvae. However, the highest mortality was observed in the essential oil of S. officinalis leaves, C. sativum seeds, F. vulgare seeds, D. carota flowers, and O. majorana leaves with LC50 = 23.050 μl/l air, 68.925 μl/l air, 95.075 μl/l air, 99.300 μl/l air, and 100.925 μl/l air, respectively. Other oils showed an LC50 between 101 and 183 μl/l air

Study and optimization of a 600V Pseudo-vertical GaN-on-silicon rectifier by finite elements simulation

International audienceReal performance breakthrough have been demonstrated for high voltage, high power, high temperature and high frequency devices by using wide band-gap semiconductors, such as 4H-SiC, GaN and AlGaN, over the previously existing devices based on group-IV and III-V lower band-gap semiconductor material. One of the key devices for high power switching converter is a fast rectifier. 4H-SiC based Schottky diodes are now commercially available from many companies with breakdown voltage up to 1,7 kV. However, bulk SiC substrates are very expensive and the hetero-epitaxial SiC layers on low cost substrates have too many crystal defects. These are the main reasons for the ongoing research programs toward GaN based-rectifiers on Silicon substrate for medium voltage range applications (600 V < Vbr < 1.2 kV)

Study and optimization of a 600V Pseudo-vertical GaN-on-silicon rectifier by finite elements simulation

International audienceReal performance breakthrough have been demonstrated for high voltage, high power, high temperature and high frequency devices by using wide band-gap semiconductors, such as 4H-SiC, GaN and AlGaN, over the previously existing devices based on group-IV and III-V lower band-gap semiconductor material. One of the key devices for high power switching converter is a fast rectifier. 4H-SiC based Schottky diodes are now commercially available from many companies with breakdown voltage up to 1,7 kV. However, bulk SiC substrates are very expensive and the hetero-epitaxial SiC layers on low cost substrates have too many crystal defects. These are the main reasons for the ongoing research programs toward GaN based-rectifiers on Silicon substrate for medium voltage range applications (600 V < Vbr < 1.2 kV)

The impact of paper constituents on the efficiency of mechanical strengthening by polyaminoalkylalkoxysilanes

International audienceThe aim of the research was to evaluate the influence of certain components of paper such as lignin and papermaking additives (fillers and sizing) on the efficiency of a recently proposed treatment for simultaneous deacidification and mechanical strengthening with polyaminosiloxane copolymer networks. Mixed mechanical and chemical pulp papers containing various additives were treated with aminoalkylalkoxysilanes (AAAS) by immersion or by spray. Upon treatment, the deposited alkaline reserve varied from 0.34 to 1.14 mol kg−1. For all the papers, copolymers formed from binary mixtures of a di- and a tri-functional AAAS provided the best improvement in the mechanical properties, i.e. in the tensile strength and the folding endurance, indicating an increase in the interfiber bonding energy and in the paper flexibility and plasticity, respectively. It was found that fillers had no influence while sizing hampered the efficiency of the treatment. The presence of mechanical pulp was shown to have a significant impact on the effect of the treatments as well by increasing the tensile resistance more than the folding endurance, indicating an increase in the paper rigidity. This observation was attributed to the response of lignin to the treatment