Assessment of clogging of managed aquifer recharge in a semi-arid region.

To overcome water scarcity issues in arid and semi-arid regions, Managed Aquifer Recharge (MAR) remains a viable and suitable solution to manage and restore aquifers. However, clogging represents a major issue that can affect the durability and efficiency of MAR structures. The aim of this study was to evaluate the extent of clogging in MAR sites (Berrechid, Morocco). To achieve this objective, two field-based studies were undertaken: the first one consists of implantation of sand-filled columns in the recharge sites to evaluate the surface and subsurface clogging. The second one consists of the implantation of pickets over a 750 m2 area in each recharge site to measure the extent of deposit thickness on the surface of the wadi bed. Results show that, despite the low rainfall (<1.4 mm/day) and the short period (91 days) of the study, the deposits thickness exceeds 3 cm in a large part of the MAR. The suspended solids concentrations measured in recharge sites ranged from 1.1 to 1.4 g/L. Due to the particles retention, the estimation of the saturated hydraulic conductivity (k) of the sand declines over 90% in the immediate entrance of the columns. The k values measured in situ during the drying period ranged from 10-5 to 10-6 m/s. The k values of the cake formed, without cracks, was about 10-8 m/s. The presence of cracks drives the entire infiltration. However, due to the high plasticity index of the MAR soil, a slight reduction of cracks opening during wetting cycles is observed. In addition, particles deposited in these cracks, would contribute actively to the reduction of infiltration. The results of this study clearly showed the MAR sites vulnerability in semi-arid regions due to physical clogging.

Ultrasonic characterisation of particle retention by a double porosity medium.

A study was undertaken to characterise the evolution of the clogging of various porous media during filtration experiments. Long-term tracer tests were carried out at various flow velocities. To highlight the effects of intraporosity on transport and retention mechanisms, both single porosity and double porosity media (DPM) were used. The presence of matrix porosity in the two investigated DPM provided additional sites, promoting retention of suspended particles (SP). The particle size distribution (PSD) of the recovered particles increased with time. However, and due to the additional retention sites in intraporosity, the changes in PSD with time were slower for tests on DPM. Ultrasonic transmission was used to detect modifications to the properties of the porous media induced by particle retention. The results demonstrate the capacity of ultrasound for detecting the evolution of physical clogging as a consequence of particle deposition.

Rosuvastatin Is Effective to Decrease CD8 T-Cell Activation Only in HIV-Infected Patients With High Residual T-Cell Activation Under Antiretroviral Therapy.

OBJECTIVE: The aim of the trial was to evaluate in patients under antiretroviral therapy (ART) the effect of rosuvastatin on cellular and soluble markers of immune activation/inflammation, as well as to identify patients who better benefit from statin administration. METHODS: IMEA-043-CESAR was a phase II open-label pilot trial that enrolled patients under suppressive ART and CD4 <500/mm. Patients received rosuvastatin (20 mg/d) for 12 weeks. The primary outcome was the variation at week 12 (W12) in the proportion of CD38HLA-DRCD8 T lymphocytes. Secondary outcomes included evolution of other markers of T-cell activation and of inflammatory biomarkers between baseline, W12, and W24. RESULTS: Fifty patients were enrolled; end points were available for 43 patients. When considering all patients, the proportion of CD38HLA-DRCD8 T cells did not significantly decline throughout the follow-up. However, the proportion of CD38CD8T cells significantly decreased at W12 [median percentage change of -22.2% (-32.3; +1.4)]. Principal component analysis allowed identification of 3 groups of patients based on their baseline activation/inflammation profiles, 1 group with elevated levels of CD8 T-cell activation, and a small group with high levels of systemic inflammation and low levels of T-cell activation. Half of the patients exhibited relatively low levels of inflammation and activation. The proportion of activated CD8 T cells significantly decreased only in the particular group of patients with high baseline CD8 T-cell activation. CONCLUSIONS: This study shows that combining rosuvastatin with effective ART can result in a sustained decrease in CD8 T-cell activation and highlights the importance of identifying patients who can benefit from specific immunotherapeutic strategies.