Géomembranes et géosynthétiques bentonitiques : la combinaison optimale pour les barrières contre le transfert de polluants

Sekizinci ulusal geosentetikler konferansı (Huitième conférence nationale sur les géosynthétiques), Istanbul, TUR, 16-/05/2019 - 17/05/2019International audienceThe equivalence of composite liners involving a geomembrane (GMB) and a geosynthetic clay liner (GCL) to regulatory composite liners with a GMB and a compacted clay liner (CCL) can offer greater environmental protection to the underlying aquifer. It is suggested that GCLs and GMBs can play a very beneficial role in providing environmental protection even though GCLs are altered by their environment due to cation exchange and wet-dry cycles or there are defects in the GMB. The performance of GMB-GCL composite liners is accessed in terms of diffusion of contaminants and in terms of advective transfer due to the presence of defects in GMBs. Experimental, numerical and empirical quantification of advective transfers are examined through single GMBs and GCLs and arecompared to GMB-CCL composite liners included in the case of aged GCLs

Angiofibrome Nasopharyngien Compliqué D\'un Syndrome De Foster Kennedy : Place De La Chimiothérapie

L\'angiofibrome nasopharyngien (FNP) est une tumeur vasculaire bénigne localement agressive. Il représente 0,05% des tumeurs de la tête et du cou et touche presque exclusivement les adolescents de sexe masculin. La chirurgie est considérée comme le traitement principal du FNP, les autres modalités thérapeutiques tels que radiothérapie et chimiothérapie sont indiquées en cas d\'extension intracrânienne avec envahissement du sinus caverneux ou de la carotide interne. Nous rapportons une observation rare de FNP, compliqué d\'un syndrome de Foster Kennedy chez une femme de 34 ans. Le traitement a consisté en une chimiothérapie (adriamycine, décarbazine) suivie d\'une radiothérapie. Nous discutons de l\'intérêt et des résultats de la chimiothérapie dans le traitement des FNP avec une importante extension intracrânienne (stade III B de la classification de Radkowski).Nasopharyngeal angiofibroma is a locally aggressive, although histologically benign, vascular neoplasm. This neoplasm accounts for 0.05% of the head and neck tumours and affects almost exclusively male adolescents. Surgery is considered as the primary treatment of nasopharyngeal angiofibroma. Other treatment modalities such as radiotherapy and chemotherapy are still recommended for intracranial extension involving the cavernous sinus or the internal carotid artery. We report a rare case of nasopharyngeal angiofibroma, further complicated with a Foster Kennedy syndrome in a 34- years-old woman. The treatment consisted in a chemotherapy (adriamycine, decarbazine) followed by radiotherapy. We discuss the relevance and the outcome of chemotherapy in the treatment of the nasopharyngeal angiofibromas with a consistent intracranial extension (stage III B of Radkowski\'s classification). Journal Tunisien d\'ORL et de chirurgie cervico-faciale Vol. 16 2006: pp. 46-4

Healthcare-associated infections in a tunisian university hospital: From analysis to action

Introduction: our study was conducted, in university hospital center (UHC) Farhat Hached of Sousse (city in Tunisian center-east), within healthcare-associated infections (HAI) epidemiological surveillance (ES) program,  based, among others, on HAI regular prevalence surveys. Our objectives are to resituate HAI prevalence rate and to identify their risk factors (RF) in order to adjust, in our hospital, prevention programs.Methods: it is a transversal descriptive study, including all patients who had been hospitalized for at least 48 hours, measuring prevalence of HAI a “given day”, with only one passage by service. Risk factors were  determined using Epiinfo 6.0, by uni-varied analysis, then, logistic  regression stepwise descending for the variables whose pResults: the study focused on 312 patients. Infected patients prevalence was 12.5% and that of HAI was 14.5 %. Infections on peripheral venous catheter (PVC)  dominated (42.2%) among all HAI identified. HAI significant RF were neutropenia (p<10-4) for intrinsic factors, and PVC for extrinsic factors (p=0,003). Conclusion: predominance of infections on PVC should be subject of specific prevention actions, including retro-information strategy, prospective ES, professional practices evaluation and finally training and increasing awareness of health personnel with hygiene measures. Finally,  development of a patient safety culture with personnel ensures best adherence to hygiene measures and HAI prevention

Géomembranes et géosynthétiques bentonitiques : la combinaison optimale pour les barrières contre le transfert de polluants

Sekizinci ulusal geosentetikler konferansı (Huitième conférence nationale sur les géosynthétiques), Istanbul, TUR, 16-/05/2019 - 17/05/2019International audienceThe equivalence of composite liners involving a geomembrane (GMB) and a geosynthetic clay liner (GCL) to regulatory composite liners with a GMB and a compacted clay liner (CCL) can offer greater environmental protection to the underlying aquifer. It is suggested that GCLs and GMBs can play a very beneficial role in providing environmental protection even though GCLs are altered by their environment due to cation exchange and wet-dry cycles or there are defects in the GMB. The performance of GMB-GCL composite liners is accessed in terms of diffusion of contaminants and in terms of advective transfer due to the presence of defects in GMBs. Experimental, numerical and empirical quantification of advective transfers are examined through single GMBs and GCLs and arecompared to GMB-CCL composite liners included in the case of aged GCLs

Comportement en régime transitoire de deux étanchéités composites GM-GSB

International audienceIn general, interface transmissivity is obtained based on measurements of the steady-state flow in composite geomembranes (GMBs) geosynthetic clay liners (GCLs). However, transient flow rate has not been studied prior to this study. It has been already noticed that its consideration can lead to an important increase in predicted effluent volumes penetrating the liner, the subgrade soil and the groundwater. The goal of the study presented herein is to study the transient state by quantifing the reduction in flow rate with time for two different composite liners. In these composite liners, a needle-punched GCL was combined to a high-density polyethylene GMB. The first GCL contained granular sodium bentonite and the second GCL contained powdered sodium bentonite. While the GCLs hydrated their water content and deformation were quantified. To this aim, various tests were conducted over various periods of time, corresponding to different flow rate values through the composite liner. Relationships between the flow rate and water uptake of the GCL on one side and swell on the other side are given for both GCLs. The results show that the mass per unit area in addition to the granulometric distribution of bentonite in GCL specimens may affect the hydration process and the flow rate evolution through composite liners. In addition, For both GCLs, the deformation follows the same trend of evolution with water content

Evaluation des géosynthétiques pour la protection environementale

International audienceThe objective of this Invited Lecture is to give an updated overview of transfer properties of geosynthetic liner materials used in environmental applications. In relation with the high temperatures that can be encountered and the risk for desiccation of geosynthetic clay liners (GCLs), retention curves of GCLs are first discussed. An overview is then given on the quantification of advective transfers though intact geomembranes, virgin or after exposure on site, and through multicomponent GCLs. The question of the experimental quantification of advective transfers through composite liners is also addressed, when geomembranes or the film or coating of a multicomponent GCL is damaged. The question of puncture protection of geomembrane thanks to drainage geocomposites, which is becoming a concern in France, is briefly addressed and evidences the lack of data in this matter. Finally, the diffusion of organic and inorganic species through virgin and aged geomembranes and GCLs is discussed based on a literature review including the most recent data. It is expected that the synthesis of the most recent available data presented here in terms of elementary transfer mechanisms, either advective or diffusive, will contribute to the improvement of the quantification of transfer through barrier systems and to an improvement of puncture protection of liner materials in order to improve the global performance of barrier systems

Effet de la contrainte de confinement sur la courbe de rétention d'eau d'un géosynthétique bentonitique aiguilleté

International audienceGeosynthetic clay liners (GCLs) are placed at the bottom of waste disposal facilities where they hydrate from the subsoil and eventually from a hydraulic head on geomembranes (GMs) defects. Predicting hydration behavior of GCLs requires knowledge of the water-retention properties of the GCL along wetting paths. Given that GCLs could be subjected to different ranges of vertical stresses that are induced by the weight of the supported waste, the confining stress could affect water-retention properties of GCLs and should be investigated. To do so, a laboratory methodology to establish the water-retention curves (WRCs) of needlepunched GCLs under stress was undertaken. Various constant vertical stresses corresponding to different weights of the supported waste were applied to GCL specimens placed in controlled-suction oedometers. Suction values were selected so as to mimic a wetting path from the initial dry state to zero suction. Suction was controlled by using controlled suction techniques with controlled humidity imposed by a saturated saline solutions and using the osmotic technique with polyethylene glycol (PEG) solutions. Measurements were undertaken on oedometer systems as to apply confining stresses and have been complemented by standard saturated oedometer swelling tests. The data obtained confirm that increasing the stress on to the GCL results in less, albeit faster, water uptake, which could emphasize on recommendations about rapidly covering GCLs after they are placed at the bottom of a waste disposal facilities. Finally, the potential validity of the state-surface concept, which was developed in unsaturated soil mechanics, is discussed using van Guenuchten's and Fredlund and Xing's equations for water retention curves

Etude numérique des transferts advectifs dans les étanchéités composites

International audienceThis study presents numerical simulations of advective flow through a composite geomembrane geosynthetic clay liner (GMB-GCL). In the past, GCLs were considered homogeneous materials, but they actually consist of a special layered composite structure that combines two types of materials, geotextiles and bentonite, which are connected together by various processes. One could imagine that, when the GCL hydrates, the different water-retention properties of the geotextile and the bentonite affect the hydraulic behaviour of engineered systems, including GMB-GCL composite liners. To investigate this question, the advective flow through a composite liner modelled as a GCL and a damaged GMB was numerically simulated to evaluate how the hydraulic properties of the unsaturated geotextile and bentonite influences the temporal evolution of advective flow through composite liners. Results are compared with measured water-retention curves of geotextiles and bentonite. The simulation indicates that the reproduced flow rate is influenced by the desaturation of the geotextile that occurs as the bentonite hydrates. The reduction in flow rate is thus governed by the hydraulic conductivities of the geotextile and the bentonite, both of which vary with degree of saturation

Synthèse de la performance des géosynthétiques pour la protection environnementale

International audiencehis paper, which is based on an Invited Lecture for the 7th International Conference on Environmental Geotechnics, gives an updated overview of the properties of transfer of geosynthetic liner materials used in environmental applications. To begin, the water-retention curves of geosynthetic clay liners (GCLs) are discussed, with the focus being on the high temperatures that can be encountered and the concomitant risk of desiccation. Next, an overview is given of quantifying advective transfer through intact geomembranes (virgin or after exposure on site) and through multicomponent GCLs. Experimental quantification of advective transfer through composite liners is also addressed, whereby geomembranes or the film or coating of a multicomponent GCL is damaged. Finally, based on a literature review including the most recent data, the discussion turns to the diffusion of organic and inorganic species through virgin and aged geomembranes and GCLs. The synopsis of the most recent data presented here in terms of elementary transfer mechanisms, either advective or diffusive, should contribute to improving the quantification of transfer through barrier systems. These four topics were selected as they correspond to the fields of expertise of the co-authors in which they have been publishing in the past 20 years