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Water is a significant primary resource on the Earth's surface. Fresh water is essential for human beings and for the stability and sustainable development of any nation. Many regions in the interior of Syria have an insufficient water balance. This has caused severe shortages of freshwater as a result of climate change. Syria's main source of fresh water, rivers and groundwater, suffers from low levels due to the lack of rainfall amounts. The war in Syria exacerbated water stress, in particular the effects of the war on water sources such as the Euphrates River and the ‘Feijah’ source that feeds the capital Damascus. All of this has prompted us to seek other non-traditional sources such as atmospheric water, which is a renewable and relatively clean source. This paper is considered to be the first of its kind in Syria. Experimental results from semi-arid and arid regions have shown good potential for harvesting dew and fog water as a supplementary and complementary source to the existing freshwater supply.

In this article, we consider the average age minimization problem where a central entity schedules $M$ users among the $N$ available users for transmission over unreliable channels. It is well-known that obtaining the optimal policy, in this case, is a difficult task. Accordingly, the Whittle’s index policy has been suggested in earlier works as a heuristic for this problem. However, the analysis of its performance remained elusive. In the sequel, we overcome these difficulties and provide rigorous results on its asymptotic optimality in the many-users regime. Specifically, we first establish its optimality in the neighborhood of a specific system’s state. Next, we extend our proof to the global case under a recurrence assumption, which we verify numerically. These findings showcase that the Whittle’s index policy has analytically provable optimality in the many-users regime for the AoI minimization problem. Finally, numerical results that showcase its performance and corroborate our theoretical findings are presented.

This work is devoted to the study of the dynamics of combustion wave propagation in oxygen-enriched mixtures of n-heptane with air and jet fuel "Jet A-1" in a small-size pulsed detonation combustor (PDC) with a diameter of 20 mm and a length less than 1 m. Experiments are carried out after the PDC reaches a stationary thermal regime when changing the equivalence ratio (ϕ = 0.73-1.89) and the oxygen-to-air ratio ([O2/air] = 0.15-0.60). The velocity of the combustion wave is determined by measuring the propagation time of the flame front between adjacent pressure sensors that form measurement segements along the PDC.

The dynamics of the thrust of a jet-type pulse detonation combustor (PDC) operating on heptane/air mixtures enriched in oxygen is studied. It has been established that with simultaneous enrichment of the mixture in fuel and reduction in the oxygen-to-air equivalence ratio, the thrust characteristic of the PDC deteriorates significantly: an increase in ф from 0.8 to 2.15 leads to a decrease in the thrust by almost 65%. Addition of oxygen to the heptane/air mixture is a decisive factor here, which is expressed in the direct dependence of the thrust on the oxygen content in the mixture: at [O2/air] = 0.76, the thrust reaches 200 N against 60 N at [O2/air] = 0.1.

Two variants of the limitations are analysed: in the first case the cycles are compared at the same degree of adiabatic compression, in the second – within the same interval of limiting temperatures. The values of the thermal efficiency and pressure intervals are compared, as well as the introduced additional criteria for assessing the thermodynamic perfection: the specific volume work, the criterion of irreversibility, and the nondimensional value Z, characterizing the fraction of the effective work from the mechanical work obtained per cycle. The analysis carried out has revealed that a detonation engine possesses an advantage over some parameters, especially over the thermal efficiency, but its superiority is not absolute.

International audience; The development of a biomonitor in the context of multiple-element contamination in urban environments was tested by comparing element transfer in edible crops and poplar (Populus trichocarpa Torr. ´ Populus maximowiczii A. Henry cutlivar 'Skado'). A multielemental analysis was performed with various common edible crops (cucumber [Cucumis sativus L.], pepper [Capsicum annuum L.], cabbage [Brassica oleracea L.], and lettuce [Lactuca sativa L.]) and the Skado poplar cultivar grown on soils that received sediments dredged from water canals in the 1960s. Sediments were distributed unevenly on the soil, allowing us to sample two types of areas that were either weakly (Area 1) or highly (Area 2) contaminated, mainly by Cd, Pb, and Zn. We registered an accumulation of Cd and Zn in the edible parts of crops, with higher values recorded for leafy vegetables than for fruit vegetables. We did not detect any accumulation of Pb in the plant species studied. We calculated the fresh mass that must be consumed daily to reach tolerable daily intake (TDI) recommendations for each element and found evidence that Cd could be ingested in sufficient amounts to reach the TDI in this context. Poplar and pepper leaves accumulated more Cd and Zn than the edible parts of the study crops grown on both substrates, which suggests that poplar and pepper may be suitable species for biomonitoring element transfer to vegetation in this context.

The results of the mathematical simulation of the coal-water fuel particle in the conditions of electric-spark discharge have been given. It has been found that the CWF particle can ignite even in a relatively low (Tg

Urban gardening has recently experienced rapid development; however, the risk of the transfer of toxic elements from neighboring industry needs to be evaluated. We performed a multi-elemental analysis with several common edible crops (cucumber, pepper, cabbage, and lettuce) and poplar grown directly on a titanium ore landfill as a maximized scenario of exposure. Despite elevated concentrations of soil Ca, Fe, Mn, and Ti resulting from the industrial process, we did not register higher accumulation of these elements in the edible parts of crops or in poplar leaves grown on red gypsum compared with the control soil. Only S concentrations were higher in plants grown on the red gypsum, especially for cabbage. The principal component analysis among elements for plants grown on red gypsum indicated that S and Mn were accumulated by different plant species than Cd, Cu, and Zn. The poplar clone had a significantly higher transfer of S and Cr than the control and is a suitable tree species for monitoring element transfer to vegetation in this industrial context. By comparing our data with tolerable daily intake (TDI) recommendations, we demonstrated the low risk of cultivating edible crops directly on an industrial substrate in a maximized scenario of exposure, except for Cr, for which the toxicity depends on the bioavailable form. However, we did not consider the cumulative effects of the various elements because there are no current guidelines, and further research is needed to address this question.

International audience; Tailings dumps require mercury stabilization to prevent air pollution by evaporated mercury, which can be achieved through plant covers. Plants are considered a net sink for atmospheric Hg via incorporation into leaf tissues. However, most studies related to Hg uptake by plants have considered plants exposed to only atmospheric Hg, whereas in the case of tailings dumps, plants are potentially exposed to both soil and atmospheric Hg. The goal of this work is to evaluate the relative contributions of root and atmospheric pathways by growing poplar (Populus trichocarpa X Populus maximowiczii/var Skado) cuttings on either control or polluted substrates and under either natural or controlled exposure conditions. We showed that foliar Hg concentrations significantly increased with age, reaching 120 ng g(-1) dry mass when poplars were exposed to Hg-contaminated substrate under natural exposure. Remarkably, we did not observe significantly different Hg concentrations in poplar leaves grown on either the control or polluted substrates when cultivated together in growth chambers. Our set of data prompted us to conclude that Hg entry into poplar leaves is exclusively through an atmospheric pathway. Our results are discussed in line with existing literature.

International audience; Although current Hg emissions from industrial activities may be accurately monitored, evidence of past releases to the atmosphere must rely on one or more environmental proxies. We used Hg concentrations in tree cores collected from poplars and willows to investigate the historical changes of Hg emissions from a dredged sediment landfill and compared them to a nearby control location. Our results demonstrated the potential value of using dendrochemistry to record historical Hg emissions from past industrial activities.

National audience; Les projets PHYTOSED échelle 1 et BIOFILTREE ont comme objectifs de démontrer la pertinence de la phytostabilisation aidée couplée à la valorisation de la biomasse en bois-énergie. A grande échelle, sur plusieurs hectares de terres polluées par les éléments traces, la technique de phytostabilisation aidée a été mise en oeuvre en testant des protocoles différents (ex : amendement chimique dans le cas de PHYTOSED Echelle 1 et amendement biologique dans le cas de BIOFILTREE). Le retour d’expérience a permis de valider l’utilisation d’espèces végétales pertinentes pour la phytostabilisation (ex : canche cespiteuse, peupliers SKADO) et de définir des protocoles pour la mise en oeuvre de cette technique en fonction des caractéristiques des sols pollués. Les résultats issus de la première année de suivi ne mettent pas en évidence d’effet significatif des amendements sur la diminution des transferts de Zn et de Cd dans les feuilles des espèces végétales étudiées (canche, saules, peupliers). En revanche, l’inoculation de peupliers SKADO a un effet positif sur le rendement en biomasse de ces arbres. La poursuite de l’analyse des transferts de polluants vers les parties récoltables des végétaux devrait permettre de vérifier l’effet des amendements sur ce paramètre et d’orienter les végétaux vers une filière de valorisation pertinente.

International audience; We developed an integrated bioremediation strategy that combines two poplar clones with rhizospheric microorganisms, exploiting the complex interactions evolved for the mutual benefit of both organisms, in which plant roots provide habitat, nutrients and exudates to microbial populations, whereas microbes facilitate mineral nutrition of plants The rationale behind combining tree species and mycorrhizal fungi resides in the fact that poplar species selected are fast growing, producing large amount of harvestable biomass and capable of forming arbuscular mycorrhizal and ectomycorrhizal symbiosis with fungi. Hosting different mycorrhizal types might be of functional importance for plant nutrition and has been shown to contribute to metal tolerance of host plants as fungi can reduce the metal uptake by the plant by sequestration, extracellular precipitation and biosorption to the cell walls. Indeed, a number of recent data support the hypothesis that mycorrhizal fungi play a filtering/sequestering role on plant roots enhancing root to shoot metal ratio and increasing survival rate in harsh conditions Implementations of large scale field trials of poplars (SRC) inoculated with symbiotic microorganisms have been set up. Three sites of about 1 ha have been selected on the basis of (i) contaminants pollution level/history, (ii) hydrological/soil conditions, (iii) ongoing soil remediation research. The first site is a former agricultural area contaminated for nearly a century by metals due to the deposit of waste waters from the city of Paris. The second site is an industrial tailing pond contaminated by mercury and arsenic. The third site is a former agricultural soil that received large amounts of metal-enriched sediments. Poplars were planted and inoculated or not with a consortium of mycorrhizal fungi. Mycorrhizal species were chosen from results of molecular analyses of the mycorrhizal diversity of poplar roots collected from several metal-polluted sites. Genomic analyses revealed a predominance of Glomus and Hebeloma species. Two year after planting, woody biomasses were estimated using dendrometric parameters. Mycorrhizal poplars produced significantly more biomass than non inoculated ones. Height, diameter, and basal area of inoculated trees varied among the three studied sites and were generally between 15 and 35% higher when compared to non inoculated trees. From these experimental sites, we have also developed a strategy for isolating fungal strains of interest. We have therefore isolated a set of ectomycorrhizal and endomycorrhizal isolates, as well as fungal endophytes from poplar roots. The isolated strains were first characterized and tested in metal tolerance assays and the most tolerant strains were used in a second set of experiments for their capacity to improve plant growth under controlled conditions. Four fungal strains were able to stimulate growth of their host plants. The two most promising strains, belonging to the group of dark-septate endophytes, were find to be tolerant to a set of metals and significantly improve plant growth. We also succeeded in isolating and producing in vitro large scale inocula of several endomycorrhizal isolates. The usefulness of symbiotic inocula for biomass production on metal-polluted sites, as well as their potential for improving the efficiency of phytotechnologies in the remediation process will be further discussed.

International audience