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Sabbahi S.,Institute National Of Recherche En Genie Rural Eaux Et Forets Inrgref | Ben Ayed L.,Institute National Agronomique Of Tunis | Boudabbous A.,Laboratoire Microorganismes et Biomolecules Actives
Journal of Water and Health

The aim of this study was to evaluate the photobactericidal effect of four photosensitizers (PSs) with different structural and physico-photochemical properties, namely mesotetracationic porphyrin (T4MPyP), dianionic rose Bengal (RB), monocationic methylene blue (MB) and neutral red (NR). Their photokilling activity was tested in vitro on pathogenic bacteria such as Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) suspended in nutrient broth (NB) and in phosphate buffered saline (PBS) through following their influence on the PSs antimicrobial efficacy. Photodynamic inactivation (PDI) experiments were performed using visible light (L) and different PSs concentrations (20-70 μM). The ability of these PSs to mediate bacterial photodynamic inactivation was investigated as a function of type of PS and its concentrations, spectral and physico-chemical properties, bacterial strain, irradiation time and suspending medium. Indeed, they showed antibacterial effects against S. aureus and P. aeruginosa with significant difference in potency. Staphylococcus aureus suspended in NB showed 0.92 log units reduction in viable count in the presence of T4MPyP at 20 μM. Changing the suspending medium from NB to PBS, S. aureus was successfully photoinactivated by T4MPyP (20 μM) when suspended in PBS at least time exposure (10 and 30 min), followed by MB and RB. © IWA Publishing 2013. Source

Ghazouani W.,CIRAD - Agricultural Research for Development | Ghazouani W.,Institute National Of Recherche En Genie Rural Eaux Et Forets Inrgref | Marlet S.,CIRAD - Agricultural Research for Development | Marlet S.,Institute National Of Recherche En Genie Rural Eaux Et Forets Inrgref | And 3 more authors.
Irrigation and Drainage

Community-managed irrigation systems are commonly faced with problems of low system-level performance. A comprehensive survey was undertaken to assess and quantify the causes of the low irrigation performance in a community-managed oasis in southern Tunisia. At the irrigation system level, results showed that irrigation intervals were double those that had been expected (19-21days). The main cause was inappropriate farmers' practices at field level where the irrigation duration was almost twice the expected 10h ha -1. The extension of date palm plantation and technical dysfunctions played a less important role as they were counterbalanced by cancellation of irrigation in some plots. At the field scale, excessively long irrigation duration resulted from the joint effects of small fields, poor maintenance of field-level water delivery systems, uncontrolled night irrigation events and low farmer commitment. This situation emphasizes the question of efficiency and sustainability of irrigation systems when farmers subvert collective rules. Further, the situation raises the question of equity among farmers which hinders their support for the water users' association and the strict application of water allocation rules. These findings should help identify an appropriate approach and lead to positive changes in the management of community irrigation systems. © 2011 John Wiley & Sons, Ltd. Source

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