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The Ichkeul Lake ecosystem, Northern of Tunisia, has been registered as a biosphere reserve in 1977 (MAB-UNESCO Convention), a UNESCO World Heritage site in 1979, and a RAMSAR site in 1980. Damming and global warming drought drastically diminished the fresh water supply to this lake. This leads to water level and salinity fluctuation throughout the year. Consequently, the water clarity of this shallow wind-stressed lake was altered and if this siltation continues to increase, will seriously affects the hydromorphology and ecology of this wetland. Therefore, to study the hydrodynamic water circulation in the lake and the transport of the Total Suspend Matter (TSM), hydrodynamic and transport models were calibrated and applied to this environment. Numerical model predictions based on water level, temperature and salinity sensitivity to the bed roughness show that the Delft 3D-Flow model reproduced well the measured data with RMSE < 0.027 for water level. Keywords: Delft3D-FLOW, Hydrodynamic circulation, Ichkeul Lake, Sedimentary material, TSM, Water clarity

This paper deals with the inverse problems of wells' location and transmissivity estimation in a saturated porous media. Wells are considered as circular holes and the heterogeneous domain is divid...

This paper aims to determine the origin and processes of groundwater salinization in the Lebna coastal aquifer in northeastern of Cap Bon, Tunisia and to identify the main sources involved in the ecosystem alterations in this zone. To reach these goals, detailed geological and hydrogeological data were used in combination with geochemical and geophysical methods . The results show that the chloride, sodium and nitrate concentrations and electrical conductivity values exceed the World Health Organization WHO standard for drinking water. Further, the groundwater chemistry is classified into two main water facies : Na-Cl and Ca-Cl. Geochemical diagrams and the Saturation Index (SI) depicted two natural factors at the origin of salinization of the shallow aquifer, i.e., seawater intrusion by mixing processes and water-rock interaction by mineral dissolution and reverse cation exchange. Moreover, we showed that agricultural activities are the main source of NO 3, SO4 and K ions and contribute to groundwater contamination with increasing chloride and nitrate concentrations. Based on geophysical results, we found that the seawater intrusion reaches 2.5 Km in the longitudinal direction from the sea inland and approximately 100 m in the aquifer depth. In conclusion, we were found several groundwater salinization sources in Lebna coastal aquifer, whereas, the principal mineralization origin is the seawater intrusion. This salinization influences the ecosystem change. Unfortunately, the groundwater in Lebna area is unsuitable for human drinking and irrigation uses.

The construction of dams on the Ichkeul Lake rivers, along with drought, has increased the sedimentation problem and caused the decrease of its storage capacity. Therefore, this work aims to highlight the factors responsible for water clarity deterioration. Through the multi-date MODIS imagery analysis, a Water Turbidity Index (WTI) was used to assess the turbidity of the lake and a Delft3D-FLOW hydrodynamic model was used to determine the effect of wind, water level, temperature, and salinity on the turbidity of the lake’s waters. The effect of prevailing wind was analyzed for the two hydrological years 2014–2015 (R2 = 0.3989) and 2015–2016 (R2 = 0.4219). It was found that the water transparency decreases with the increase of wind speed. Besides, the model calibration showed the sensitivity of water temperature and salinity to the lake’s bed roughness. Contrariwise, the water level was not significantly influenced. Consequently, the use of roughness n = 0.018 decreases the errors between observed and simulated data. Altogether, the methodology used in this work allows decision makers to monitor the temporary and spatial water turbidity fluctuations in the Ichkeul Lake.

© 2018 American Chemical Society. A novel strategy to biobased chemicals with a branched carbon skeleton is introduced. Hereto, small sugars, such as 1,3-dihydroxyacetone, are coupled catalytically to obtain branched C6 sugars, such as dendroketose, in high yield at mild conditions. By bringing this branching step up front, at the level of the sugar feedstock (branching-first), new opportunities for the synthesis of useful chemicals arise. Here, we show that the branched sugar can be efficiently valorized into (i) new branched polyols and (ii) short branched alkanes. The first route preserves most of the original sugar functionality by hydrogenation with Ru/C and renders access to branched polyols with three primary alcohol groups. These molecules are potentially interesting as plasticizers, cross-linkers, or detergent precursors. The second valorization route demonstrates a facile hydrodeoxygenation of the branched sugars toward their corresponding branched alkanes (e.g., 2-methylpentane). The highest alkanes yields (>65 mol % C) are obtained with a Rh/C redox metal catalyst in a biphasic catalytic system, following a HDO mechanism. In the short term, commercial integration of these monobranched alkanes, in contrast to branched polyols, is expected to be straightforward because of their drop-in character and well-known valuable octane booster role when present in gasoline. Accordingly, the branching-first concept is also demonstrated with other small sugars (e.g., tetroses) enabling the production of branched C6-C8 sugars and thus also branched C5-C8 alkanes after HDO. ispartof: ACS Sustainable Chemistry & Engineering vol:6 issue:6 pages:7940-7950 status: published

The decrease of fresh water supply from connected rivers induces the reverse of gravity flow from Bizert Lagoon which increases the salinity and the total suspended matter (TSM). Therefore, multi-date MODIS images were analyzed by GIS to calculate and identify the spatial distribution of WTI, TSM indicator. Then, the relationship between wind conditions and TSM’s resuspension in Ichkeul Lake was clarified. After that, the cluster analysis and the temporal fluctuation of daily wind speed; rainfall, and the Potamogeton pectinatus phenology were used to interpret the seasonal distribution of the turbid water. Consequently, the linear correlation between WTI and observed data was found (R2 = 0.66; r = 0.809) and proved by ANOVA test, where P = 0.00143 (

In this paper, we focus on the identification of wells’ positions and fluxes/flows from the knowledge of overspecified data: hydraulic head and flux, on a part of the domain boundary. The used method is based on minimizing a constitutive law gap functional. We consider two inverse problems: in the first one overspecified conditions are available throughout the entire domain boundary; in the second inverse problem, in addition to the wells, boundary condition are also unknown on an inaccessible part of the domain boundary.

A multi-method geophysical survey, using time-domain electromagnetic (TDEM) fields, is conducted on the north-eastern coastal aquifer of Cap Bon, Tunisia. The aim of the study is to investigate the inland extent saltwater intrusion, to estimate the fresh-saltwater transition zone, and to characterize the lithologic spatial variability of the underground layers. Moreover, the TDEM is used to determine both fluid resistivity and bulk resistivity which are required to calculate the porosity by applying the Archie’s equation. The survey of TDEM profiles is carried out along the left and right overbanks of the Lebna river from the coast until the Lebna dam. The interpretation and the analysis of these profiles allow us to better identify the flux exchanges between the river and the underlying aquifer. On the basis of the 1D and 2D longitudinal and transversal resistivity profiles as well as the existing boreholes data and groundwater quality, it seems that the freshwater-saltwater interface is moving forward inland. Furthermore, electromagnetic results combined to the Archie’s law show that the porosity values are at the ranges of 12–36 and 5–31% for the Quaternary outcropping and Pliocene formation, respectively.

Artificial miniproteins that are able to target catalytic sites of matrix metalloproteinases (MMPs) were designed using a functional motif-grafting approach. The motif corresponded to the four N-terminal residues of TIMP-2, a broad-spectrum protein inhibitor of MMPs. Scaffolds that are able to reproduce the functional topology of this motif were obtained by exhaustive screening of the Protein Data Bank (PDB) using STAMPS software (search for three-dimensional atom motifs in protein structures). Ten artificial protein binders were produced. The designed proteins bind catalytic sites of MMPs with affinities ranging from 450 nm to 450 μm prior to optimization. The crystal structure of one artificial binder in complex with the catalytic domain of MMP-12 showed that the inter-molecular interactions established by the functional motif in the artificial binder corresponded to those found in the MMP-14-TIMP-2 complex, albeit with some differences in geometry. Molecular dynamics simulations of the ten binders in complex with MMP-14 suggested that these scaffolds may allow partial reproduction of native inter-molecular interactions, but differences in geometry and stability may contribute to the lower affinity of the artificial protein binders compared to the natural protein binder. Nevertheless, these results show that the in silico design method used provides sets of protein binders that target a specific binding site with a good rate of success. This approach may constitute the first step of an efficient hybrid computational/experimental approach to protein binder design.

In this paper, we present an original methodology for recovering boundary conditions and hydraulic parameters in an aquifer domain. Boundary data are identified from the knowledge of over-specified boundary data on another part of the boundary. Then parameters, here wells’ positions and fluxes, are recovered by the use of the reciprocity principle (Andrieux and Ben Abda, Mech Res Commun 20:415–420, 1993; Andrieux and Ben Abda, Inverse Probl 12:553–564, 1996). The boundary recovering method is based on the minimization of an energy-like error functional (Andrieux et al., Inverse Probl 22:115–133; Baranger and Andrieux, 2010).

In this work, we present a new mathematical method that allows recovering of the wells fluxes and hydraulic heads on a part of the boundary where they are not known, for an aquifer domain having overspecified boundary data on another part of its boundary. The method is based on the minimisation of an energy-like error functional of Andrieux and Ben Abda [Inverse Probl. 22 (2006) 115–133] for the missing-data recovering step and on the Reciprocity Gap principle of the same authors [Inverse Probl. 12 (1996) 553–564] for point sources identification.

Matrix metalloproteinases (MMPs) are a family of enzymes that have been recognized as promising therapeutic and diagnostic targets for the treatment and detection of human cancers. This rises from their unique ability to degrade all components of the extracellular matrix and their overexpression at different stages of tumor progression. The specific involvement of MMPs in the oncogenic processes has speeded up the efforts that have been made for the past 20 years to develop and evaluate MMP inhibitors (MMPIs) as potential anti-cancer agents. However, bringing an MMPI to the point of clinical approval is still a challenge. In this review, we provide an overview of the structure and function of MMPs along with their implication in cancer development. Furthermore, we focus on the literature concerning the development of broad spectrum natural and synthetic MMPIs, with emphasis on their limitations and the disappointing results of most clinical trials. The failure of broad spectrum MMPIs highlighted the need for the development of selective inhibitors that fully discriminate between different members of the MMP family. As a future perspective on the development of potent MMPIs, we also report in this review a novel structure-based strategy developed in our group to design new mini-protein ligands for MMP inhibition by functional motif grafting.

Two bait delivery systems for the oral immunization of dogs against rabies were tested in small scale field trials in a semi-rural area in Tunisia: bait delivery to owned dogs during door to door visits of households (door to door baiting) and distribution of baits on transect lines (transect line baiting). A prototype bait (DBL2) configured for industrial production and containing either sulfadimethoxine (SDM) as a systemic marker or Rhodamine B as a topical marker was used. The overall proportion of dogs which took a bait and presented topical marker staining after door to door baiting was 59.1%. The total time and costs spent per bait accepting dog averaged 34 person minutes and US$4, respectively. Unconsummated baits were readily recovered. No unprotected human contacts with baits were recorded. Door to door baiting is a very specific but time-consuming method that enables a safe administration of vaccine baits to owned dogs. For transect line baiting, baits were distributed at a density of ca 3000 baits per km2 along double transect lines. Baits were recovered after 20 h. According to the proportion of SDM positive serum samples, 24.1% of owned dogs in the baiting area had consumed baits. Of all owned and ownerless dogs, presumably free-roaming during transect line baiting, >40% had consumed baits. The total time and costs spent per bait accepting dog averaged 48 person minutes and ca US$20, respectively. The household census revealed 32 direct human contacts with the bait matrix which corresponds to 1.4% of inhabitants. Placing baits on transect lines gives the possibility to vaccinate dogs not accessible by vaccination systems which base on dog owner participation. However, the method is not specific, less safe than other systems, not easily accepted by the human population, and costly.

International audience; This paper focuses on the inverse ElectroCardioGraphy problem which consists in recovering the electrical potential and flux on the heart from electrical potential on the body surface. An energy-like error functional introduced in Andrieux et al. [3] and a generalized least-squares method are performed in the context of this ill-posed problem of missing boundary data recovering. Numerical experiments with 2D domains highlight the efficiency of the proposed methods as well as their robustness in the model context.

We propose in this Note a method of identifying leak zones in a saturated and homogeneous porous domain by solving a Cauchy problem. The method is based on the minimisation of an energy-like error functional procedure developed in 2006 by Andrieux and Baranger. To cite this article: X. Escriva et al., C. R. Mecanique 335 (2007).