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In Burkina Faso, vegetable production is a very important asset for its socio-economic development. However, this production faces many constraints that negatively affect its potential. The use of organic fertilization appears to be an alternative to address these constraints and could also promote sustainable agricultural production. In such a context, this study was conducted on tomato using two bio-fertilizers based on local substrates (Bokashi compost and compost enriched with Trichoderma harzianum). The objective was to assess the efficiency of the two bio-fertilizers by determining their effects on tomato yield and soil physico-chemical properties. It was conducted from 2018 to 2020 in Soala using a randomized Fischer block design with six treatments in three replications. The treatments were T0 (control), T1 (NPK+urea), T2 (Bokashi compost), T3 (compost enriched with Trichoderma harzianum), T4 (T1+T2) and T5 (T1+T3). The results showed that the bio-fertilizers alone contributed to maintain the neutrality of soil pH and very significantly improved its C, N, P and K content. Moreover, in combination with or not with NPK+urea, they influenced significantly plant growth, yield components and yield of tomato compared to T0 plot. In these years of trials, compost enriched with Trichoderma harzianum in combination with or not with NPK+urea, was found to be the most improving tomato yield and the increase was more than 300%. This compost could be therefore recommended to farmers in agriculture in general and particularly for vegetable production.

Iron (Fe) is one of the essential nutrients for plant growth which is involved in several physiological functions. Hence, there are intensive efforts to improve plant tolerance to Fe deficiency, by genotypic screening and by the use of adapted physiological tools. The intend of the current study was to explore the seed priming effect with salicylic acid (SA 0.25 mM) and hydrogen peroxide (H2O2 20 mM), either separately applied or combined, on plant growth, nutritional elements status (Fe and potassium K), root acidification and photosynthetic activity in two S. carnosa cultivars (Sidi Khlif and Kalbia) with different tolerance to such constraint. Under unprimed conditions, Fe deficiency decreased plant growth, chlorophyll concentration, in addition to Fe and K contents. Moreover, it affected the photosynthetic activity by inhibiting the net CO2 assimilation rate and increasing the transpiration rate of both cultivars, following a reduced water use efficiency. The changes above described were much less pronounced in Sidi Khlif than in Kalbia. The stomatal conductance increased in Fe-deficient leaves of both cultivars, suggesting that the photosynthesis impairment should be attributed to non-stomatal factors. Interestingly, priming seeds with both agents significantly improved the growth performance and the rhizosphere acidification of deficient S. carnosa plants. However, the D + SA + H2O2 treatment had the most beneficial effect on S. carnosa plant growth. The degree of this stimulation may vary depending on the cultivar, the tissue and the priming agent applied. This could be owing to the photosynthetic performance modulation, leading to more efficient nutrient uptake.

The riparian communities of the Zou basin of West Africa rely heavily on drinking water supplied by fractured aquifer systems. This study aims to provide accurate fracture maps and derived products...

Background Housefly (Musca domestica L. 1758) larvae are used in various parts of the world for animal feeding either by exposing substrates for natural oviposition or in industrial systems involving an adult rearing unit to produce eggs that are then placed in a substrate suitable for larval development. In order to develop M. domestica rearing system in Benin, effects of five types of food (pineapple, papaya, banana, honey, and a mixture of milk + sugar) on some biological parameters (female fecundity, adult mortality, egg hatching, pupation, and emergence time and rates) have been evaluated. Results Flies fed with pineapple and milk + sugar showed the highest fecundity (respectively 321 and 325 eggs per female within 10 days). Adult mortality rates decreased significantly with flies fed with honey (27% in 10 days) and milk + sugar (37%) compared to flies fed on local fruits (57 to 62%). Only minor differences were observed between the five foods in egg hatching, pupation and emergence rates. Conclusion This study showed that pineapple can be used to feed M. domestica instead of the conventional and more expensive milk + sugar mixture without major impact on the efficiency of M. domestica rearing.

In this paper, we consider a problem of a three-dimensional free surface flow over an obstacle lying on the bottom of an infinite channel. The flow is supercitical, irrotational, stationary and the...

International audience; We propose and study a data completion algorithm for recovering missing data from the knowledge of Cauchy data on parts of the same boundary. The algorithm is based on surface representation of the solution and is presented for the Helmholtz equation. This work is an extension of the data completion algorithm proposed by the two last authors where the case of data available of a closed boundary was studied. The proposed method is a direct inversion method robust with respect to noisy incompatible data. Classical regularization methods with discrepancy selection principles can be employed and automatically lead to a convergent schemes as the noise level goes to zero. We conduct 3D numerical investigations to validate our method on various synthetic examples.

Towards eliminating toxic substances from electronic devices, Croconic Acid (CA) has great potential as a sublimable organic ferroelectric material. While studies on CA thin films are just beginning to emerge, its capability to be integrated in nanodevices remains unexplored. We demonstrate at the laterally nanoscopic scale robust ferroelectric switching of a stable enduring polarization at room temperature in CA thin films, without leakage. The challenging ferroelectric characterization at the nanoscale is performed using a unique combination of piezoresponse force microscopy, polarization switching current spectroscopy and concurrent strain response. This helps rationalize the otherwise asymmetric polarization-voltage hysteresis due to background noise limited undetectable switching currents, which are statistically averaged in macrojunctions but become prevalent at the nanoscale. Apart from successfully estimating the nanoscopic polarization in CA thin films, we show that CA is a promising lead-free organic ferroelectric towards nanoscale device integration. Our results, being valid irrespective of the ferroelectrics' nature; organic or inorganic, pave the way for fundamental understandings and technological applications of nanoscopic polarization reversal mechanisms.

Spin-resolved photoemission spectroscopy experiments are performed on perfluorinated Co-phthalocyanine (F16CoPc) deposited onto ferromagnetic Co(001) to examine how doping (here with fluorine) of an organic semiconductor influences the interfacial electronic properties and whether the formation of highly spin-polarized interface states is possible. It is found that this latter property, initially reported for the nonfluorinated Pc, is also present for the fluorinated system Co/F16CoPc. This result shows that doping an organic semiconductor, which is an important and effective method to tailor the electronic transport properties of the molecules, does not inhibit the presence of a highly polarized spinterface.

The protection of the aquatic environment while managing the risk of water scarcity in the Mediterranean region is challenging. Ensuring future sustainability of water resources needs improved monitoring networks and early warning system of future trends of water quality. A specific concern is given to nonpoint source pollution from agriculture, which is often the main source of water quality degradation in rivers. In this work, we focused on the Joumine river basin, a rural-catchment situated north Tunisia dominated by agricultural activities and exposed to eutrophication problems. Aiming to present an assessment framework of the spatial-temporal water quality variability and quantify "pressure-impact" relationships, we used a physically based modeling approach involving the river/basin integrated model PEGASE (Planification Et Gestion de l'ASsainissement des Eaux). PEGASE simulates watercourses physicochemical quality depending on the morphology of the drainage network, hydrometeorological conditions and natural and anthropogenic influences. Simulation results showed a better description of Joumine river water quality and helped in identifying exposed areas to nutrients export. Results have also emphasized the contribution of different pollution sources. We were able to examine the potential impact of agriculture diffuse pollution and we found that Nitrate is the element mostly threatening water quality. The nutrients patterns suggest that climate and farming practices are important factors controlling their transfer. These findings demonstrate that the adopted assessment approach in investigating the behavior of the studied hydrosystem can be a useful support to develop an appropriate surface water quality management program in a semiarid context.

Fly larvae, in particular those of house fly (Musca domestica) and black soldier fly (Hermetia illucens), are increasingly considered for animal feed worldwide. A simple way to produce fly larvae is to expose suitable substrates to attract adult flies that will lay eggs in the substrates from where larvae will be subsequently extracted. This study aims to evaluate the potential of animal manures and agri-food wastes for maggot production and to identify the fly species developing in the substrates. Experiments were conducted in the Republic of Benin. Twenty-six substrates were left uncovered for 10 hours and maggots were harvested after four days. Fresh substrates were then added to residual substrates and left uncovered for another 10 hours for another production cycle. In total, three production cycles were monitored. In the first cycle, nearly 100% of the flies were house flies but black soldier flies appeared in the following cycles. The result showed that crop and agri-food substrates produced more larvae than manures. The highest yield at the first production cycle was obtained with the mixture of soybean bran and maize grain pericarp. Maize bran, pig manure and chicken manure also showed potential for maggot production. Other substrates such as cow and sheep/goat manure produced nearly no maggot when used alone but the amount of larvae substantially increased when attractants such as chicken offal were added, or when mixed with pig and chicken manure. Production decreased with the production cycles for the majority of substrates, except for mixtures based on spent grain and pineapple grain, which produced a large amount of larva at the second harvest. The activity of maggots led to temperature elevation and reduction of substrate biomass. This study showed that several substrates, in particular soybean bran, maize bran, pig manure and chicken manure show potential for maggot production.

We study a new diluted magnetic semiconductor system based on the spin of the ionized acceptor Cr$^+$. We show that the negatively charged Cr$^+$ ion, an excited state of the Cr in II-VI semiconductor, can be stable when inserted in a CdTe quantum dot (QD). The Cr$^+$ attracts a heavy-hole in the QD and form a stable hole-Cr$^+$ complex. Optical probing of this system reveals a ferromagnetic coupling between heavy-holes and Cr$^+$ spins. At low temperature, the thermalization on the ground state of the hole-Cr$^+$ system with parallel spins prevents the optical recombination of the excess electron on the 3$d$ shell of the atom. We study the dynamics of the nano-magnet formed by the hole-Cr$^+$ exchange interaction. The ferromagnetic ground states with M$_z$=$\pm$4 can be controlled by resonant optical pumping and a spin relaxation time in the 20 $\mu$s range is obtained at T=4.2 K. This spin memory at zero magnetic field is limited by the interaction with phonons.

International audience; Spatiotemporal spin noise spectroscopy is combined with dynamic light scattering in order to reach spatial resolutions down to ∼λ/10. Applied to a system of localized electron spins, an insulating n-doped CdTe layer, this allows us to reveal long spin jump distances ∼ 2.7 μm. Spin noise spectra at large wave vectors q (q 1) provide a snapshot of the spin dynamics before jump (therefore not affected by spin motion), while at smaller q, spin motion sets in. This allows us to unravel the contributions of spin-orbit and hyperfine fields in the electron spin relaxation and to determine self-consistently all parameters relevant to the spin dynamics. We propose a phenomenological equation inspired by studies of atomic jump diffusion by neutron scattering, which includes the relevant spin relaxation mechanisms and the effect of time of flight of the spin fluctuation across the laser spot. This modeling reproduces all experimental results.

The age of ore deposits constitutes a decisive element in understanding their formation. Deciphering their precise chronology may be a challenge in the absence of mineral phases that can be dated by conventional geochronometers. Fluorite is very common either as the major or accessory mineral in a wide variety of ores and may provide information regarding the origin and timing of mineralizing fluid flows. In this contribution, we explore U–Pb dating on fluorite crystals from the world-class carbonate strata-bound fluorite ore of Pierre-Perthuis in Burgundy (Morvan massif, France). The uranium distribution within fluorite is mapped using induced fission-track and synchrotron radiation X-ray fluorescence nano-imaging, showing that higher U content is measured in an overgrowth of fluorite (Flog) as a discrete band. Preservation of a micrometer-thick zonation in U, associated with other substituted elements such as Sr, Y, Fe and Zr, implies that neither solid-state diffusion nor dissolution–recrystallization occurred. These U-bearing external fluorite overgrowths contain solid inclusions of about 30 µm globular pyrite crystals with a mean δ34S of −23.6 ± 0.4 ‰V-CDT. We propose that the U incorporation in the fluorite lattice results from the development of a redox front during bacterial sulfate reduction. Flog generation sampled and analyzed by laser ablation–inductively coupled plasma mass spectrometry (LA-ICP-MS) on four different crystals provides identical U–Pb ages within the limits of analytical uncertainty. Considered altogether, these four crystals yield an age estimate of 40.0 ± 1.7 Ma, not corrected for matrix-related elemental fractionation. Our results show that fluorite LA-ICP-MS U–Pb geochronology has potential for dating distinct crystal growth stages, although further research should be conducted to evaluate its accuracy.

International audience; The quantum states of nano-objects can drive electrical transport properties across lateral and local-probe junctions. This raises the prospect, in a solid-state device, of electrically encoding information at the quantum level using spinflip excitations between electron spins. However, this electronic state has no defined magnetic orientation and is short-lived. Using a novel vertical nanojunction process, these limitations are overcome and this steady-state capability is experimentally demonstrated in solid-state spintronic devices. The excited quantum state of a spin chain formed by Co phthalocyanine molecules coupled to a ferromagnetic electrode constitutes a distinct magnetic unit endowed with a coercive field. This generates a specific steady-state magnetoresistance trace that is tied to the spin-flip conductance channel, and is opposite in sign to the ground state magnetoresistance term, as expected from spin excitation transition rules. The experimental 5.9 meV thermal energy barrier between the ground and excited spin states is confirmed by density functional theory, in line with macrospin phenomenological modeling of magnetotransport results. This low-voltage control over a spin chain's quantum state and spintronic contribution lay a path for transmitting spin wave-encoded information across molecular layers in devices. It should also stimulate quantum prospects for the antiferromagnetic spintronics and oxides electronics communities.

International audience; Sugarcane yellow leaf virus (SCYLV) is an aphid-transmitted virus for which Melanaphis sacchari is the main vector. Almost all sugarcane varieties grown in Florida are susceptible to SCYLV infection. In this study, we investigated the prevalence of SCYLV in accessions of Sorghum bicolor which is another natural host of this virus. Two field experiments, one in 2016 with 19 sorghum lines and the other in 2017 with 15 lines, were established at Belle Glade, FL. Stalks collected randomly in planted and ratoon crops were tested by tissue-blot immunoassay (TBIA) and reverse transcription-polymerase chain reaction (RT-PCR). Over the two-year period, 366 of 423 S. bicolor samples tested positive by TBIA but SCYLV was detected by RT-PCR in only 12 of 161 randomly selected subsamples. Full genome sequences of SCYLV, sugarcane mosaic virus (SCMV) and a new marafivirus were obtained by high-throughput sequencing (HTS) from three TBIA positive sorghum samples. HTS data for all three viruses were confirmed by RT-PCR. The SCMV isolates from S. bicolor appeared to be a new strain of this virus species. Positive reaction of S. bicolor by TBIA using SCYLV antibodies could not be systematically associated with plant infection by SCYLV or another virus. This suggested the occurrence of a non-specific serological reaction with an unknown S. bicolor antigen. SCMV and the new marafivirus were also detected in Sorghum almum, suggesting that this weed is a reservoir for S. bicolor-infecting viruses in Florida.

PtSe2 is attracting considerable attention as a high mobility two-dimensional material with envisioned applications in microelectronics, photodetection and spintronics. The growth of high quality PtSe2 on insulating substrates with wafer-scale uniformity is a prerequisite for electronic transport investigations and practical use in devices. Here, we report the growth of highly oriented few-layers PtSe2 on ZnO(0001) by molecular beam epitaxy. The crystalline structure of the films is characterized with electron and x-ray diffraction, atomic force microscopy and transmission electron microscopy. The comparison with PtSe2 layers grown on graphene, sapphire, mica, SiO2 and Pt(111) shows that among insulating substrates, ZnO(0001) yields films of superior structural quality. Hall measurements performed on epitaxial ZnO/PtSe2 with five monolayers of PtSe2 show a clear semiconducting behaviour and a high mobility in excess of 200 cm2 V−1 s−1 at room temperature and up to 447 cm2 V−1 s−1 at low temperature.

Tomato mottle virus (ToMoV) is a single-stranded DNA (ssDNA) begomovirus transmitted to solanaceous crops by the whitefly species complex (Bemisia tabaci), causing stunted growth, leaf mottling, and reduced yield. Using a genetic repertoire of seven genes, ToMoV pathogenesis includes the manipulation of multiple plant biological processes to circumvent antiviral defenses. To further understand the effects of whitefly feeding and whitefly-transmitted ToMoV infection on tomato plants (Solanum lycopersicum &lsquo, Florida Lanai&rsquo, ), we generated comprehensive protein profiles of leaves subjected to feeding by either viruliferous whiteflies harboring ToMoV, or non-viruliferous whiteflies, or a no-feeding control. The effects of whitefly feeding and ToMoV infection were measured both locally and systemically by sampling either a mature leaf directly from the site of clip-cage confined whitefly feeding, or from a newly formed leaf 10 days post feeding (dpf). At 3 dpf, tomato&rsquo, s response to ToMoV included proteins associated with translation initiation and elongation as well as plasmodesmata dynamics. In contrast, systemic impacts of ToMoV on younger leaves 10 dpf were more pronounced and included a virus-specific change in plant proteins associated with mRNA maturation and export, RNA-dependent DNA methylation, and other antiviral plant processes. Our analysis supports previous findings and provides novel insight into tomato&rsquo, s local and systemic response to whitefly feeding and ToMoV infection.

International audience; Viruses in the genus Mastrevirus (family Geminiviridae), including those infecting sugarcane, have natural geographical ranges almost exclusively restricted to Africa and the Indian Ocean islands off the African coast. Only sugarcane white streak virus (SWSV) in Barbados and sugarcane striate virus (SStrV) in Florida and Guadeloupe are known to infect a few sugarcane varieties in the Western Hemisphere. In this study, PCR assays were developed to detect these two viruses in sugarcane. Five hundred and seventy-one DNA samples from Saccharum species and interspecific hybrids from the Miami World Collection of sugarcane and related grasses were tested for the presence of SStrV and SWSV by PCR. No variety was found infected by SWSV but SStrV was detected in 19 varieties. PCR data were confirmed by sequencing amplified fragments (248 bp). These fragments shared 93%-100% nucleotide identity with SStrV sequences from the GenBank database. SStrV isolates were distributed in six phylogenetic groups, including the four strains of the virus. Most varieties infected by SStrV originated from Asia, thus confirming a previous hypothesis stating that this virus originated from this continent. Absence of SStrV in commercial sugarcane in Florida also suggested that this virus has not been spread in this location, while infected plants have been present for several decades.

Doping a two-dimensional semiconductor with magnetic atoms is a possible route to induce magnetism in the material. We report on the atomic structure and electronic properties of monolayer WSe$_2$ intentionally doped with vanadium atoms by means of scanning transmission electron microscopy and scanning tunneling microscopy and spectroscopy. Most of the V atoms incorporate at W sites. These V$_W$ dopants are negatively charged, which induces a localized bound state located 140 meV above the valence band maximum. The overlap of the electronic potential of two charged V$_W$ dopants generates additional in-gap states. Eventually, the negative charge may suppress the magnetic moment on the V$_W$ dopants., Comment: 12 pages, 4 figures

International audience; We demonstrate radio-frequency tuning of the energy of individual CdTe/ZnTe quantum dots (QDs) by Surface Acoustic Waves (SAWs). Despite the very weak piezoelectric coefficient of ZnTe, SAW in the GHz range can be launched on a ZnTe surface using interdigitated transducers deposited on a c-axis oriented ZnO layer grown on ZnTe containing CdTe QDs. The photoluminescence (PL) of individual QDs is used as a nanometer-scale sensor of the acoustic strain field. The energy of QDs is modulated by SAW in the GHz range and leads to characteristic broadening of time-integrated PL spectra. The dynamic modulation of the QD PL energy can also be detected in the time domain using phase-locked time domain spectroscopy. This technique is in particular used for monitoring complex local acoustic fields resulting from the superposition of two or more SAW pulses in a cavity. Under magnetic field, the dynamic spectral tuning of a single QD by SAW can be used to generate single photons with alternating circular polarization controlled in the GHz range.

International audience; Absolute dating is needed to check and calibrate the relative Martian chronology presently available from meteoritic crater counting. For such purpose, a new analytical system (KArMars) has been developed to experiment the feasibility of in-situ K-Ar for future landing planetary missions. It consists in a laser ablation-based system built to vaporize a reproducible volume of rock. Potassium content is measured by laser-induced breakdown spectroscopy (LIBS) and argon by Quadrupole Mass Spectrometry (QMS). Instrument calibration, and checking of the reliability of the measurements for Martian analyses, requires terrestrial analogues. For such purpose, total chemistry, electron microprobe analyses, flame absorption spectrometry and mass spectrometry have been performed in order to qualify the stoichiometry, the mineralogy, the K concentration and the Ar isotopic composition from a collection of old terrestrial rocks. These new analyses coupled with published data allowed us to select mineral phases (e.g. feldspars, phlogopite, muscovite, amphibole) showing a large range of K content (0.3–8.5 wt%). All these mineral phases display a K-Ar age older than 300 Ma. Hence, the content of radiogenic Ar atoms per gram is within the range of Martian samples (on the order of 1 Ga for 0.4 wt% of K). We have shown that the ablated mass can be precisely estimated by measurement of Ar extracted from a similar mineral of known amount of radiogenic Ar content per gram. Then, it has been possible to derive a well-defined relationship between the ablation time and the sample mass extracted from UV-laser ablations for different minerals. Using an isochron approach from multiple ablations of several samples analyzed as unknowns, we have shown that KArMars can be successfully used for dating samples with different compositions, and with ages varying by an order of magnitude from 0.3 to 3 Ga. In-situ K-Ar ages obtained here for plagioclase and amphibole crystals display uncertainties as low as about 10%, and with accuracy, i.e. difference with the reference age, of only 10%. Such results further support in-situ K-Ar dating based on QMS and LIBS instruments as a reliable approach to be implemented onboard Martian rovers. In case a return mission is made possible, KArMars can also be a valuable tool to select the most relevant samples for return and ensure onsite which samples are representative of most of the surface at a given landing site.

The discovery of stable room temperature ferroelectricity in Croconic Acid, an organic ferroelectric material, with polarization values on par with those found in inorganic ferroelectric materials and highest among organic ferroelectric materials, has opened up possibilities to realize myriads of nano-electronic and spintronic devices based on organic ferroelectrics. Such possibilities require an adequate understanding of the ferroelectric properties of Croconic Acid grown on surfaces that are commonly employed in device fabrication. While several macroscopic studies on relatively larger crystals of Croconic Acid have been performed, studies on thin films are only in their early stages. We have grown thin films of Croconic Acid on gold and cobalt surfaces, which are commonly used in spintronic devices as metallic electrodes, and studied the ferroelectric response of the films using ex-situ Piezoresponse Force Microscopy at room temperature. We show that the polarization reversal in Croconic Acid domains is sensitive to the substrate surface. Using the same experimental protocol, we observe the robust polarization reversal of a single, mostly in-plane electrical domain for a cobalt substrate, whereas polarization reversal is hardly observed for a gold substrate. We attribute this difference to the influence of substrates on the Croconic Acid molecular networks. Our study suggests that to realize devices one has to take care about the substrate on which Croconic Acid will be deposited. The fact that polarization switching is robust on cobalt surface can be used to fabricate multifunctional devices that utilize the cobalt-Croconic Acid interface., 21 pages, 14 figures

International audience; In North Africa, the Algerian margin is made of basement blocks that drifted away from the European margin, namely the Kabylia, and docked to the African continental crust in the Early Miocene. This young margin is now inverted, as dated Miocene (17 Ma) granites outcrop alongshore, evidencing kilometre-scale exhumation since their emplacement. Age of inversion is actually unknown, although Pliocene is often considered in the offshore domain. To decipher the exhumation history of the margin between 17 and 5 Ma, we performed a coupled apatite fission track (AFT) and (U-Th-Sm)/He (AHe) study in the Cap Bougaroun Miocene granite. AFT dates range between 7 +/- 1 and 10 +/- 1 Ma, and mean AHe dates between 8 +/- 2 and 10 +/- 1 Ma. These data evidence rapid and multi-kilometre exhumation during Tortonian times. This event cannot be related to slab break-off but instead to the onset of margin inversion that has since developed as an in-sequence north-verging deforming prism.

A novel method of determining the total uncertainty in the integrated intensity of fitted emission lines in multipeaked emission spectra is presented. The proposed method does not require an assumption of the type of line profile to be specified. The absolute difference between a fit and measured spectrum defines the uncertainty of the integrated signal intensity and is subsequently decomposed to determine the uncertainty of each peak in multiline fits. Decomposition relies on tabulating a weighting factor, which describes how each peak contributes to the total integral uncertainty. Applications of this method to quantitative approaches in laser-induced breakdown spectroscopy analysis are described.

The knowledge about groundwater flow conditions within Volta river basin in Benin, has restricted information coming to piezometry, water storage time, water path, and water quality. A good groundwater resources assessment of this sudano-sahelian area, is a huge condition for the sustainable management of water resources, which since the part of the 20th century is facing a severe drought that leads to a greater aridity. This article provides a summary with the main elements of carbon isotope (13C and 14C) as well as tritium (3H) coupled with hydrogeological and hydrochemical data. The goal is to improve the initial water recharging and the groundwater flow system within the aquifer. Two main results can be produced from the groundwater chemistry. First, the interactions between groundwater and clay minerals related to the residence time of groundwater are indicated by a slight evolution of Ca-HCO3 and Ca-Mg-HCO3 to Na-HCO3. Beside that towards water types Cl-NO3 indicates the anthropogenic influence on groundwater, related to agricultural activities and sanitation conditions. The carbon-14 activity measured on the TDIC is between 17.29 and 85.47 pmC. Therefore, it contains some samples covering a wide period of time from now to the Holocene implying a continuous system recharging over time. All the data confirm the assumption of a homogeneous, largely unified aquifer system with a multi-layer structure, but it also points out the low resource sustainability and a strong anthropogenic contamination of the most superficial horizons.

In central Benin, fluoride concentrations in groundwater generally exceed the national and WHO guideline values (1.5 mg/L) and are locally above 7 mg/L (max. 7.19 mg/L). In this area, aquifers are found in a Precambrian bedrock made of migmatitic gneiss and granites . Recent hydrogeochemical studies have shown that the occurrence of fluoride in groundwater in this area is of geogenic origin. The aims of this investigation are to determine the sources of fluorine in the bedrock and to assess the role of geology on the mineralization and high fluoride concentrations in groundwater. Thirty-five rock samples were collected in different areas that display contrasting concentrations of fluoride in groundwater. We carried out analyses of petrology, mineralogy and geochemistry on the samples. The results show that fluorine concentrations vary between 100 and 2900 ppm. Several fluorine-bearing minerals such as (biotite, muscovite , amphibole), titanite , fluorite , fluor-apatite, fluor-allanite, epidote and chlorite were identified. Groundwaters with elevated concentrations of fluoride are found in geological aquifers units and watershed rocks that contain fluorine bearing minerals. Biotite occurring in the granitic formations has the highest fluorine concentrations and appears as the most important contributor to the total fluorine from the bedrock to the groundwater.

Resume La pourriture grise est l’une des principales maladies menacant la tomate marocaine. Cette maladie est controlee souvent par des fongicides. Or, ces derniers constituent un veritable danger pour la sante humaine et l’environnement. Ainsi, cette etude s’inscrit dans le cadre de recherche des alternatives, inoffensives et non polluantes, telles les extraits de plantes aromatiques et medicinales. Dans la presente etude, les extraits de quatre plantes medicinales et aromatiques ( Lavandula officinalis , Thymus vulgaris , Cymbopogon citratus et Melissa officinalis ) ont ete testes pour leur pouvoir antifongique in vitro et in vivo sur Botrytis cinerea . Les resultats obtenus revelent qu’ in vitro , les extraits aqueux de Lavandula officinalis , Thymus vulgaris et Cymbopogon citratus possedent tous une activite antifongique importante, alors que Melissa officinalis se montre la moins efficace. Par ailleurs, les extraits aqueux de Cymbopogon citratus et de Thymus vulgaris sont les plus efficaces sur les plantes, tandis que ceux de Melissa officinalis et Lavandula officinalis n’ont aucun effet sur le pathogene. Sur le fruit, seul l’extrait aqueux de Cymbopogon citratus s’avere le plus efficace contre B . cinerea . Par consequent, les extraits aqueux de Cymbopogon citratus et de Thymus vulgaris sont les plus envisageables pour le controle biologique de la pourriture grise.

In this paper, we consider a problem of a supercritical free surface flow over an obstacle lying on the bottom of a channel in 2D. The flow is irrotational, stationary and the fluid is ideal and incompressible. We take into account both the gravity and the effects of the superficial tension. The problem is nonlinear, it is formulated by the Laplace operator and the dynamic condition defined on the free surface of the fluid domain (Bernoulli equation). Using the perturbation stream function, we linearize the problem and we give a priori properties of the solution. These a priori properties allow us to construct a space where we can use the Lax–Milgram’s theorem to prove the existence and the uniqueness of the solution of the problem.

Sugarcane yellow leaf virus (SCYLV), the causal agent of yellow leaf disease, naturally infects at least three plant species in Florida: sugarcane (Saccharum spp.), the weed Columbus grass (Sorghum almum) and cultivated sorghum (S. bicolor). All three hosts are also colonized by the sugarcane aphid (Melanaphis sacchari), the main vector of SCYLV worldwide. To understand the high incidence of SCYLV observed in sugarcane commercial fields and in germplasm collections, we investigated the transmission efficiency of SCYLV from sugarcane and Columbus grass to sugarcane using the sugarcane aphid and a spider mite (Oligonychus grypus) that also tested positive for SCYLV in Florida. Healthy and SCYLV-infected leaf pieces of sugarcane and Columbus grass carrying viruliferous aphids or spider mites were transferred to virus-free plants of the yellow leaf susceptible sugarcane cultivar CP96-1252. Three- and 6-months post inoculation, the 108 aphid-inoculated plants of Columbus grass and the 90 mite-inoculated plants of sugarcane tested negative for SCYLV by tissue blot immunoassay (TBIA) or reverse transcription polymerase chain reaction (RT-PCR). Similar results were obtained for 162 aphid-inoculated plants of sugarcane, except for two plants that tested positive for SCYLV by TBIA and RT-PCR. In two field experiments planted with SCYLV-free and virus-infected sugarcane (cultivar CP96-1252), only 18–28% of healthy plants became infected during a 24- to 28-month period. SCYLV prevalence in these field experiments did not differ between aphicide treated and untreated plots. Incidence of M. sacchari haplotypes in the Everglades agricultural area also indicated that the predominant haplotype that is currently colonizing sugarcane was not a vector of SCYLV in Florida. Lack of virus transmission by the spider mite suggested that this arthropod only acquired the virus when feeding on infected plants but was unable to transmit SCYLV. The current vector of SCYLV in Florida remains to be identified.

The technique of spectroscopic ellipsometry is a powerful tool for the characterization of the optical properties of materials. This technique represents a significant refinement over the semi-empirical approach to optical constants determination using BRDF (Bidirectional Reflectance Distribution Function) measurements of a finite set of grain sizes for each mineral. It also allows obtaining, not only the optical constants, but also information about the dependence of optical response on sample orientation respect to the illuminating light beam. In this work, we present our experimental approach to derive optical constants of Martian analogue materials based on an infrared ellipsometry technique. We derived the optical constants of gypsum between 750 and 5000 ​cm−1 (2–13 ​μm) using data obtained with an infrared spectroscopic Mueller ellipsometer. Thanks to the high sensitivity of the ellipsometric measurements, and despite of a rather complex data analysis protocol, the results obtained for the gypsum samples show that it is possible to successfully use this technique for direct determination of optical constants of natural minerals. The method discussed here can provide the planetary science community with laboratory derived optical constants of a large number of minerals and materials (either natural or synthetic).

International audience; We analyse the influence of optically generated non-equilibrium phonons on the spin relaxation and effective spin temperature of an individual Cr atom inserted in a quantum dot. Using a three pulses pump-probe technique, we show that the spin relaxation measured in resonant optical pumping experiments strongly depends on the optical excitation conditions. We observe for an isolated Cr in the dark a heating time shorter than a few hundreds ns after an initial high power non-resonant excitation pulse. A cooling time larger than a few tens of µs, independent on the excitation, is obtained in the same experimental conditions. We show that a tunable spin-lattice coupling dependent on the density of non-equilibrium phonons can explain the observed dynamics. Low energy excitation conditions are found where the Cr spin states Sz=±1 can be efficiently populated by a non-resonant optical excitation, prepared and read-out by resonant optical pumping and conserved in the dark during a few µs.

The field of tunnelling spintronics has flourished through the study of magnetic tunnel junctions (MTJs) with MgO barriers. The combination of high spintronic performance and low effective barrier heights has enabled new technologies, ranging from next-generation memories to bio-inspired computing. This combination is made possible by structural defects such as oxygen vacancies. So far, experiments have pegged an energy separation between these localized states and the Fermi level, while theory has predicted that these are in fact occupied states. To rationalize the defect-mediated potential tunnelling landscape, we have performed experiments in which we tune the MTJ's Fermi level by altering one electrode's work function. We find that switching the top electrode from FeCoB to FeB increases the amplitude of defect-mediated barrier heights. Ab initio theory attributes this increase to an increased energy separation between the localized states of single and double oxygen vacancies and the Fermi level. We thus extract a rationalized potential landscape of tunnelling across oxygen vacancies in MgO involving occupied states. In junctions with high R.A. product such as ours, this leads to a picture of hole tunnelling.

We report on the potential of a new spin noise spectroscopy approach by demonstrating all-optical probing of spatiotemporal spin fluctuations. This is achieved by homodyne mixing of a spatially phase-modulated local oscillator with spin-flip scattered light, from which the frequency and wave vector dependence of the spin noise power is unveiled. As a first application of the method we measure the spatiotemporal spin noise in weakly n-doped CdTe layers, from which the electron spin diffusion constant and spin relaxation rates are determined. The absence of spatial spin correlations is also shown for this particular system.

In this study, aqueous solutions of gallic acid (GA) were irradiated in an electron beam (EB) accelerator under different experimental conditions (various initial GA concentrations, presence or absence of oxidant and oxygen). For an initial GA concentration of 50 μM, complete GA degradation was achieved with an absorbed dose of 850 Gy in the presence of dissolved oxygen. Both GA removal and mineralization are favored when oxygen is present. The addition of persulfate anions (S2O82−) or hydrogen peroxide (H2O2) also increased the efficiency of GA degradation and mineralization. For an absorbed dose of 14 kGy, GA mineralization reached approximately 45%, 55%, and 72% for the EB, EB/H2O2, and EB/S2O82−systems, respectively. Three transformation products were tentatively identified in the presence of oxygen, these are the result of hydroxylation and ring opening reactions. No specific transformation product was found for the sulfate radical anion (SO4–●) reaction. Four additional compounds, including a dimer, were identified in oxygen-free solutions. These findings demonstrate that water radiolysis based on EB irradiation is an efficient process to activate H2O2 and S2O82− anions and is an advanced oxidation process (AOP).

This work deals with the microbiological study along the water chain in Belbedji, a local government in the northwest of the Zinder region in the Republic of Niger. For this study, two (2) standpipes, thirty (30) families and ninety (90) samples were selected in order to follow the variation of water microbiological quality. For that the parameters studied are the total coliforms, the fecal coliforms and the E. coli. From these parameters we calculated the indication or the index of the microbiological quality (MQI) by the method of Bovesse and Depelchin, 1980. The variations of the fecal contamination at the level of the families in the different phases are represented on maps. At the water marker, 100% of families have good microbiological quality. After the transport of water, on 3.33% of the families the quality of the water deteriorated. After water storage, 16.66% of families had deteriorated water quality, with the passage of fecal contamination from zero to low on 13.33% of families, and fecal contamination from zero to moderate 3.33% of families.

A high spin polarization of states around the Fermi level, EF, at room temperature has been measured in the past at the interface between a few molecular candidates and the ferromagnetic metal Co. Is this promising property for spintronics limited to these candidates? Previous reports suggested that certain conditions, such as strong ferromagnetism, i.e., a fully occupied spin-up d band of the ferromagnet, or the presence of π bonds on the molecule, i.e., molecular conjugation, needed to be met. What rules govern the presence of this property? We have performed spin-resolved photoemission spectroscopy measurements on a variety of such interfaces. We find that this property is robust against changes to the molecule and ferromagnetic metal's electronic properties, including the aforementioned conditions. This affirms the generality of highly spin-polarized states at the interface between a ferromagnetic metal and a molecule and augurs bright prospects toward integrating these interfaces within organic spintronic devices.

Carbon nanotubes (CNT) are currently used as a promising family of nanovectors able to deliver different types of therapeutic molecules. Several applications dealing with CNT used as drug nanocarriers have been developed since their ability to penetrate into the cells has been proved. CNT can thus load several active molecules to various cells. In this paper, we will use molecular dynamic simulation to describe theoretically the potential of CNT to transport and deliver DNA through the formation of protamine-DNA-CNT complex.

Carbonate rocks are in general complex and commonly contain compound pore systems that can significantly affect the variations of physical properties; their petrophysical evaluation remains challenging, and the results are often uncertain. This paper presents a new approach developed to establish vuggy porosity models that can be applied to successfully estimate vuggy porosity, both connected and separate vug fraction. It involves mainly partitioning the total porosity into fractions of its basic components, such as fractures, matrix porosity, and vugs. To estimate and decompose the total porosity, wireline methods involving standard porosity and borehole electrical image logs are integrated based on rock-physics modeling and image analysis techniques through a series of steps, which specifically have particular set of procedures performed rigorously to obtain accurate results. The determined fractions of the total-vug and separate-vug porosities are related to acoustic parameters to establish total-vug and separate-vug porosity models, respectively. Core analysis and thin-section-derived optical porosity (PHIO) are used to verify the log-derived porosities and validate the newly-established total porosity partition procedure. The newly proposed vuggy porosity models yield optimal estimates that significantly match the measured quantities. They also show statistically better prediction accuracy, compared with previous models in literature, especially typical Lucia vug porosity models. In addition, the results indicate that the density log, which its combination to sonic and resistivity logs can enable separate-vug porosity calculation, is a good-total porosity estimator at least in low-touching vug zones. Together, this has proven the effectiveness of the present approach for porosity partitioning in carbonate rocks, and the vuggy porosity models derived could therefore be applied to other similar carbonate reservoir studies.

International audience; We study the emission of individual quantum dots in CdTe/ZnTe samples doped with a low concentration of Cr. In addition to dots with a photoluminescence (PL) split by the exchange interaction with a magnetic Cr atom, we observe another type of dots with a complex PL structure composed of a minimum of six lines on the exciton and biexciton and three lines on the charged excitons. In these dots, the linear polarization dependence and the magnetic field dependence of the PL behave like three similar quantum dots emitting at slightly different energies. Cross-correlation intensity measurements show that these emission lines are not independent but exchange intensities in a time scale of a few hundred nanoseconds depending on the optical excitation power. We attribute this PL structure to charge fluctuations of a Cr atom located in the vicinity the CdTe dots in the ZnTe barrier. We present a model which confirms that the presence of a single charge fluctuating between-e (Cr +), 0 (Cr 2+) and +e (Cr 3+) and located a few nm away from the dot explains the observation of three emission energies. We finally show that the interaction between the confined carriers and the nearby fluctuating localized charge can be modified by an applied static electric field which modulates the splitting of the emission lines.

A comprehensive estimation of water budget components, particularly groundwater storage (GWS) and fluxes, is crucial. In this study, we evaluate the terrestrial water budget of the Donga basin (Benin, West Africa), as simulated by three land surface models (LSMs) used in the African Monsoon Multidisciplinary Analysis Land Surface Model Intercomparison Project, phase 2 (ALMIP2): CLM4, Catchment LSM (CLSM), and Minimal Advanced Treatments of Surface Interaction and Runoff (MATSIRO). All three models include an unconfined groundwater component and are driven by the same ALMIP2 atmospheric forcing from 2005 to 2008. Results show that all three models simulate substantially shallower water table depth (WTD) with smaller seasonal variations, approximately 1–1.5 m compared to the observed values that range between 4 and 9.6 m, while the seasonal variations of GWS are overestimated by all the models. These seemingly contradictory simulation results can be explained by the overly high specific yield prescribed in all models. All models achieve similar GWS simulations but with different fractions of precipitation partitioning into surface runoff, base flow, and evapotranspiration (ET), suggesting high uncertainty and errors in the terrestrial and groundwater budgets among models. The poor performances of models can be attributed to bias in the hydrological partitioning (base flow vs surface runoff) and sparse subsurface data. This analysis confirms the importance of subsurface hydrological processes in the current generation of LSMs and calls for substantial improvement in both surface water budget (which controls groundwater recharge) and the groundwater system (hydrodynamic parameters, vertical geometry).

We demonstrate that the spin of a Cr atom in a quantum dot (QD) can be controlled optically and we discuss the main properties of this single spin system. The photoluminescence of individual Cr-doped QDs and their evolution in magnetic field reveal a large magnetic anisotropy of the Cr spin induced by local strain. This results in a splitting of the Cr spin states and in a thermalization on the lower energy states states S$_z$=0 and S$_z$=$\pm$1. The magneto-optical properties of Cr-doped QDs can be modelled by an effective spin Hamiltonian including the spin to strain coupling and the influence of the QD symmetry. We also show that a single Cr spin can be prepared by resonant optical pumping. Monitoring the intensity of the resonant fluorescence of the QD during this process permits to probe the dynamics of the optical initialization of the spin. Hole-Cr flip-flops induced by an interplay of the hole-Cr exchange interaction and the coupling with acoustic phonons are the main source of relaxation that explains the efficient resonant optical pumping. The Cr spin relaxation time is measured in the $\mu s$ range. We evidence that a Cr spin couples to non-equilibrium acoustic phonons generated during the optical excitation inside or near the QD). Finally we show that the energy of any spin state of an individual Cr atom can be independently tuned by a resonant single mode laser through the optical Stark effect. All these properties make Cr-doped QDs very promising for the development of hybrid spin-mechanical systems where a coherent mechanical driving of an individual spin in an oscillator is required., Comment: arXiv admin note: text overlap with arXiv:1606.04221, arXiv:1609.08829

We performed SQUID and FMR magnetometry experiments to clarify the relationship between two reported magnetic exchange effects arising from interfacial spin-polarized charge transfer within ferromagnetic metal (FM)/molecule bilayers: the magnetic hardening effect, and spinterface-stabilized molecular spin chains. To disentangle these effects, both of which can affect the FM magnetization reversal, we tuned the metal phthalocyanine molecule central site's magnetic moment to selectively enhance or suppress the formation of spin chains within the molecular film. We find that both effects are distinct, and additive. In the process, we 1) extended the list of FM/molecule candidate pairs that are known to generate magnetic exchange effects, 2) experimentally confirmed the predicted increase in anisotropy upon molecular adsorption; and 3) showed that spin chains within the molecular film can enhance magnetic exchange. This magnetic ordering within the organic layer implies a structural ordering. Thus, by distengangling the magnetic hardening and exchange bias contributions, our results confirm, as an echo to progress regarding inorganic spintronic tunnelling, that the milestone of spintronic tunnelling across structurally ordered organic barriers has been reached through previous magnetotransport experiments. This paves the way for solid-state devices studies that exploit the quantum physical properties of spin chains, notably through external stimuli., None

In this work we are interested in analyzing the texture of aluminum nitride thin films deposited by direct-current magnetron sputtering and high-power impulse magnetron sputtering on silicon (100) substrates. The texture characterization of aluminum nitride films was performed by X-ray diffraction. The pole figures have indicated that in both methods direct-current magnetron sputtering and high-power impulse magnetron sputtering, the microstructure is a (0001) strong fiber texture, with a tilted c-axis in the case of direct-current magnetron sputtering. Moreover, the texture analysis allowed the characterization of the cubic phase of aluminum nitride, which most likely constitutes a transition layer between the hexagonal aluminum nitride and the silicon substrate. The misfits' calculations between the different structure cells (silicon, hexagonal aluminum nitride and cubic aluminum nitride) confirm that the growth of the hexagonal aluminum nitride in the form of (0001) fiber is facilitated by this transition layer.

A detailed analysis of the photoluminescence (PL) intensity distribution in singly Cr-doped CdTe/ZnTe quantum dots (QDs) is performed. First of all, we demonstrate that hole-Cr flip-flops induced by an interplay of the hole-Cr exchange interaction and the coupling with acoustic phonons are the main source of spin relaxation within the exciton-Cr complex. This spin flip mechanism appears in the excitation power dependence of the PL of the exciton as well as in the intensity distribution of the resonant PL. The resonant optical pumping of the Cr spin which was recently demonstrated can also be explained by these hole-Cr flip-flops. Despite the fast exciton-Cr spin dynamics, an analysis of the PL intensity under magnetic field shows that the hole-Cr exchange interaction in CdTe/ZnTe QDs is antiferromagnetic. In addition to the Cr spin dynamics induced by the interaction with carriers' spin, we finally demonstrate using time resolved optical pumping measurements that a Cr spin interacts with nonequilibrium acoustic phonons generated during the optical excitation inside or near the QD.