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Актуальность исследования определяется созданием принципиально нового способа синтеза титановых порошков высокой степени чистоты из ильменитовых руд месторождений Вьетнама, содержащих в тяжелой фракции смесь ильменита с рутилом. Это одно из приоритетных направлений комплексного развития месторождений редких и редкоземельных элементов во Вьетнаме. Цель: выбор условий, методов и последовательности проведения технологических операций по обогащению вьетнамских ильменитовых руд и последующей их химической переработки с получением высокочистого титана. Объекты: ильменитовая руда месторождения Ха Тинь (Вьетнам) с высоким содержанием оксидов титана, железа, циркония и низким содержанием кремния, алюминия, редкоземельных элементов, ванадия, а также ильменитовый концентрат, полученный в результате обогащения исходной ильменитовой руды. Методы: в процессе обогащения - электростатическая сепарация, флотация, использование коллекторов, активаторов и депрессоров, добавляемых к флотореагентам; при электролитическом синтезе титана - применение расплава в виде смеси фторидов лития, натрия и калия, обладающих минимальной температурой плавления, с добавкой тетрафторида титана; выбор условий запуска электролизера, катодной плотности тока, силы тока и напряжения для осаждения титана на катоде; исследование оптимальных условий выделения титанового порошка при низких температурах с использованием безводного фтороводорода. Результаты. Показана перспективность использования методов электростатической сепарации и флотации при обогащении вьетнамских ильменитовых руд месторождения Ха Тинь. Получен ильменитовый концентрат с содержанием диоксида титана более 50 %. Обоснованы преимущества использования метода прямого фторирования ильменитового концентрата элементным фтором, позволяющего обеспечить полноту его вскрытия и отделить летучие фториды титана, ниобия, ванадия и кремния от нелетучих - фторидов железа, циркония, гафния и церия. Это позволяет оптимизировать число стадий при дальнейшем применении TiF4 в качестве материала для получения титанового порошка. При электролитическом получении титана обоснована необходимость применения расплава фторидных солей лития, натрия и калия, имеющих состав: LiF (0,465 М)-NaF (0,115 М)-KF (0,42 М), обладающего минимальной температурой плавления (454 °С) и пределами изменения концентрации K2TiF6 (25-30 %). При этом величины плотности тока и выхода по току приближаются к максимальным значениям - 3,5-4,0 А/см2 и 60-65 % соответственно. Содержание примесей в титановом порошке не превышает 0,135 %, что удовлетворяет требованиям для изготовления изделий из компактного титана. The relevance of the study is determined by the creation of a fundamentally new method for the synthesis of titanium powders of high purity from ilmenite ores of Vietnam deposits, containing a mixture of ilmenite with rutile in the heavy fraction. This is one of the priority areas for the integrated development of deposits of rare and rare earth elements in Vietnam. The main aim: selection of conditions, methods and sequence of technological operations for the beneficiation of Vietnamese ilmenite ores and their subsequent chemical processing to obtain high-purity titanium. Objects: ilmenite ore of the Ha Tinh deposit (Vietnam) with a high content of oxides of titanium, iron, zirconium and a low content of silicon, aluminum, rare earth elements, vanadium, as well as ilmenite concentrate obtained as a result of enrichment of the original ilmenite ore. Methods: in the beneficiation process - electrostatic separation, flotation, the use of collectors, activators and depressants added to flotation reagents; in the electrolytic synthesis of titanium - the use of a low-melting eutectic of fluoride salts of alkali metals with the addition of titanium tetrafluoride; selection of the conditions for starting the electrolyzer, cathode current density, current and voltage for the deposition of titanium on the cathode; investigation of the optimal conditions for the release of titanium powder at low temperatures using anhydrous hydrogen fluoride. Results. The prospects of using the methods of electrostatic separation and flotation in the dressing of Vietnamese ilmenite ores of the Ha Tinh deposit are shown. An ilmenite concentrate with a titanium dioxide content of more than 50 % was obtained. The advantages of using the method of direct fluorination of an ilmenite concentrate with gaseous fluorine are substantiated, which makes it possible to ensure both the completeness of the decomposition of the solid phase and to separate the fluorides of titanium, niobium, vanadium and silicon that pass into the gas phase from those remaining in the condensed state - fluorides of iron, zirconium, hafnium and cerium. This allows you to optimize the number of stages in the subsequent processing of titanium tetrafluoride and the synthesis of metallic titanium. In titanium electrolysis, the authors have substantiated the use of composition of the eutectic of fluoride salts of alkali metals LiF (0,465 M)-NaF (0,115 M)- KF (0,42 M), which has a minimum melting point (454 °C) and the range of changes in the concentration of K2TiF6 (25-30 %). In this case, the values of current density and current efficiency approach the maximum values of 3,5-4,0 A/cm2 and 60-65 %, respectively. The content of impurities in titanium powder does not exceed 0,135 %, which meets the requirements for the manufacture of products from compact titanium.

Non-thermal plasma is widely considered as an effective technology for applications in agriculture. Particularly, numerous reports studies have highlighted the role of plasma-activated water (PAW) for seeds germination, plant growth, stress tolerance, and antibacterial ability. The present study investigated the effects of PAW on lettuce (Lactuca Sativa L.) seed germination and seedling growth. PAW was achieved by using an atmospheric pressure dielectric barrier discharge in Ar (50%) –N2 (40%)–O2 (10%) gas mixture for treatment time ranging from 5 to 30 mn. The physicochemical properties of PAW (temperature, pH, electrical conductivity, concentrations of nitrate, nitrite, and hydrogen peroxide) were evaluated. Results show that water-activated during moderate time, 10 to 20 mn, contains reactive oxygen and nitrogen species at relevant concentration levels to have active impacts on seed germination and seedling growth. Germination potential significantly increased by about 117%, 56%, and 77% after 15 mn of treatment, for the first 3 days, respectively, compared to control. For long time PAW (25–30 mn), the germination rate is either constant or decreases. Positive effects of PAW treatments were registered on the growth parameters of seedling including stem and root length, leaf weight, leaf area and chlorophyll content, and the vigor of seedlings. Chlorophyll content significantly increased by 220% for PAW-treated 15 mn and by about 165% for PAW-treated 20 mn, respectively, compared with control. Additionally, PAW induce morphological changes on lettuce seeds which are associated with oxidizing species leading to better water and nutrients uptake.

In this paper, we are interested in entire, non-trivial, non-negative solutions and/or entire, positive solutions to the simplest models of polyharmonic equations with power-type nonlinearity \[ \Delta^m u = \pm u^{\alpha} \quad \text{ in } \mathbb R^n \] with $n \geqslant 1$, $m \geqslant 1$, and $\alpha \in \mathbb R$. We aim to study the existence and non-existence of such classical solutions to the above equations in the full range of the constants $n$, $m$ and $\alpha$. Remarkably, we are able to provide necessary and sufficient conditions on the exponent $\alpha$ to guarantee the existence of such solutions in $\mathbb R^n$. Finally, we identify all the situations where any entire non-trivial, non-negative classical solution must be positive., Comment: 18 pages, 0 figure

International audience; A new species of the genus Camellia L. (Theaceae) from Southern Vietnam is described and illustrated under the name Camellia proensis. Morphological differences between C. proensis and closely related species in the genus Camellia L. (sect. Piquetia) were identified. C. proensis is easily distinguishable from C. honbaensis, C. piquetiana and C. longii by the yellow flowers; from C. dalatensis by the glabrous twigs and leaves; from C. dongnaiensis by light yellow flowers; from C. sonthaiensis by mature fruit flat-globose, 4.0–5.5 cm tall and 8.5–10.0 cm wide. Ecological environment and distribution were also provided for this new species. The images and type specimens of this species were processed and stored in Vietnam (holotype, isotypes, DLU).

Coriander contains petroselinic acid, an isomer fatty acid of oleic acid. Coriander seed oil has been proposed as novel food ingredient in the European Union. Field experiments were performed at Auch (France) during two seasons (2010 and 2011). From flowering to maturity, fruits were harvested weekly and oil content and fatty acid (FA) compositions were determined. Fruits presented 2% more oil in 2010 than in 2011. Petroselinic acid (PA) contents was higher in 2011 than in 2010. Oil accumulation began earlier after flowering (2 DAF) in 2011. A first step in accumulation was identified between two and 21 DAF characterized by high SFA and PUFA, which decreased 21 DAF. Subsequently, PA increased to its highest concentration (30–55 DAF) and SFA and PUFA reached their lowest. These results suggest that higher concentrations of PA can be achieved by collecting fruits before full maturity.

International audience; To study the influence of the microstructure of cast iron on the adhesion of an epoxy coating, ferritic, pearlitic and austempered samples were prepared in as-received, polished and oxidized states. A pull-off test (dry adhesion) was performed before immersing in water while the cross-cut test was made after 24 days of exposition in distilled water (wet adhesion). X-rays were combined with optical microscopy (LOM) and scanning electron microscopy (SEM) for surface analysis. The adhesion of the epoxy coating on the cast iron surface firstly depends on the roughness of the surface; polished samples showed high adherence by comparison with as-received samples. On the oxidized samples, the surface oxide significantly improves the adhesion of the coating in both dry and wet states for all three sample microstructure. The presence of carbide in the structure was observed to decrease adherence.

International audience; In this research, short bamboo fiber (BF) has been used as filler in the fabrication of the composite based on polyamide 11 (PA11) by melt-mixing method. In order to improve the compatibility between BF and PA11, maleic anhydride grafted ethylene vinyl acetate copolymer (EVAgMA) was introduced into the composite preparation process. The effect of EVAgMA contents on mechanical, thermal or weathering resistant properties of the composites was investigated. In the presence of the EVAgMA, the tensile strength, impact strength and flexural modulus of composites showed the improvement in comparison to without compatibilizer. Differential scanning calorimetry (DSC) analysis indicated that the melting temperature of composites did not depend on the EVAgMA contents, while its fusion heat (ΔHm) decreased with increasing EVAgMA contents. Dynamic mechanical thermal analysis (DMTA) evaluated the role of EVAgMA on the enhancement of composites’s storage modulus (G′) in the glassy plateau and the interaction between BF and PA11 matrix. After 840 hours of accelerated weathering test, the composites using EVAgMA were decomposed faster than that of neat PA11 and PA11/BF composite. This result was also agreed with the observation of scanning electronic microscopy (SEM) images and the change of carbonyl index (CI). However, the retention of tensile properties of PA11/EVAgMA/BF composites is higher than that of PA11/BF composite.

International audience; Hibiscus sabdariffa extracts, a rich source of anthocyanin, were subjected to encapsulation in yeast cells. An encapsulation yield (EY) of 208 μg/100 mg of cells and an encapsulation efficiency (EE) of 27%, were reached after optimisation of the ratios (0.5 g wet yeast cells for 5 ml of anthocyanin extracts at 1 g·L−1) and with 10% of ethanol. The storage stability of encapsulated pigments was investigated in water and buffer pH 1.5 at 5 & 37 °C for 10 days and 90 °C for 30 min. The percentage of loss of colour was determined by colourimetry assays. The microparticles made of yeast with or without heat treatment exhibited different protecting effects (P

International audience; In the present work, a well-known corrosion inhibitor (8-hydroxyquinoline (8HQ)) was inserted within the montmorillonite platelets (8HQ-MMT) and the modified clay was incorporated (3 wt.%) into a solvent-free epoxy coating which was afterwards deposited on carbon steel substrates. First, the inhibitive action of 8HQ was investigated by electrochemical methods carried out on a bare carbon steel rotating disk electrode in a 0.1 M NaCl solution. Then, electrochemical impedance measurements were performed to assess the effect of the 8HQ-MMT in the epoxy coating for the corrosion protection. The results were compared with a reference sample constituted by the epoxy coating containing an ammonium quaternary salt-modified clay. It was shown that the two coatings presented good barrier properties. Dry and wet adherence measurements revealed an improvement of the adherence when the 8HQ-MMT was incorporated into the coating by comparison with the reference sample. It was concluded that the 8HQ mainly had an effect at the metal/coating interface but its concentration was too low to afford significant corrosion protection of the carbon steel.

International audience; This study is devoted to the analysis of the properties of continuous bamboo fiber (BF)‐reinforced polyamide 11 (PA 11) composites. The SEM observations highlighted continuity between BFs and the polymeric matrix showing a high density of hydrogen bonds. The comparative calorimetric study of the matrix and its composites showed that the crystallinity of PA 11 was not modified by the presence of bamboo fibers. The physical aging observed in PA 11 is no more observed in composites due to physical interactions between PA 11 and BFs. The mechanical properties were investigated by tensile strength and dynamic mechanical analysis. The introduction of BFs enhanced Young's modulus of the matrix by a factor of 10. The presence of BFs also improved the storage shear modulus G′ over the whole temperature range.

The present study aimed to evaluate the synergistic effects of the crude ethyl acetate extract (CEAE) from endophytic actinomycete MPT42 and essential oil (EO) of the same host plant Litsea cubeba. The isolate MPT42, exhibiting broad-spectrum antimicrobial activities and harboring all three antibiotic-related biosynthetic genes pks-I, pks-II, and nrps, was identified as Streptomycete griseorubens based on an analysis of the morphology, physiology, and 16S rDNA sequence. Minimum inhibitory concentrations (MICs) and the fractional inhibitory concentration index were used to estimate the synergistic effects of various combined ratios between CEAE or antibiotics (erythromycin, vancomycin) and EO toward 13 microbial strains including pathogens. L. cubeba fruit EO, showing the main chemical constituents of 36.0% citral, 29.6% carveol, and 20.5% limonene, revealed an active-low against tested microbes (MICs &ge, 600 &mu, g/mL). The CEAE of S. griseorubens culture exhibited moderate&ndash, strong antimicrobial activities against microbes (MICs = 80&ndash, g/mL). Analysis of the mechanism of action of EO on Escherichia coli ATCC 25922 found that bacterial cells were dead after 7 h of the EO treatment at 1 MIC (5.5 mg/mL), where 62% cells were permeabilized after 2 h and 3% of them were filament (length &ge, 6 &mu, m). Combinations of CEAE, erythromycin, or vancomycin with EO led to significant synergistic antimicrobial effects against microbes with 4&ndash, 16 fold reduction in MIC values when compared to their single use. Interestingly, the vancomycin&ndash, EO combinations exhibited a strong synergistic effect against five Gram-negative bacterial species. This could assume that the synergy was possibly due to increasing the cell membrane permeability by the EO acting on the bacterial cells, which allows the uptake and diffusion of antimicrobial substances inside the cell easily. These findings in the present study therefore propose a possible alternative to combat the emergence of multidrug-resistant microbes in veterinary and clinics.

International audience; Double-walled carbon nanotubes (DWNTs), consisting of two coaxial and weakly van der Waals coupled single-walled carbon nanotubes (SWNTs), are one of the most ideal and fundamental systems to study the effects of inter-tube coupling on the physical properties in one-dimensional structures.On this poster, we report on the investigations of individual, spatially isolated and suspended double-walled carbon nanotubes (DWNTs) by combination of high-resolution electron microscopy, electron diffraction, Rayleigh spectroscopy and Raman spectroscopy (Figure 1) [1,2]. We first present an overview of the effect of the diameters, inter-tube distance and nature (metallic or semiconducting) on the Raman signature (Radial Breathing Like [1,3,4] and Tangential Modes [4-6]) of DWNTs. We then examine the features of tangential modes and find a clear frequency shift of the inner-layer G modes as a function of the inter-tube distance with respect to the corresponding G modes in equivalent single-walled carbon nanotubes (SWNT).[4-6] These results are understood by considering the effects of the relaxation of the layers and the interaction between the relaxed structures.[7] Finally, we study the experimental excitation dependence of the G modes intensity of the constituent inner and outer SWNTs. In particular, we discuss the effects of the quantum interference between different electronic transitions on the observed behaviors.[8]References[1] D.I. Levshov et al., Carbon, 114, 141 (2017). [2] D.I. Levshov et al., Phys Rev. B 96 (2017), 195410.[3] D.I. Levshov et al., Nano Lett. 11(11) (2011), 4800. [4] H.-N. Tran et al., Adv. Nat. Sci. Nanosci. Nanotechnol. (2017), 8, 15018.[5] D. Levshov et al., J. Phys. Chem. C 119(40) (2015), 23196.[6] D.I. Levshov et al., Phys. Status Solidi B 254(11) (2017), 1700251.[7] V.N. Popov et al., Phys. Rev. B 97 (2018), 165417.[8] H.-N. Tran et al., Phys. Rev. B 95 (2017), 95 (20), 205411

International audience; We report the direct and unambiguous evidence of the existence of inner semiconducting tube (iSCT) photoluminescence (PL) from measurements performed on four individual free-standing index-identified double-walled carbon nanotubes (DWNTs). Based on thorough Rayleigh scattering, Raman scattering and PL experiments, we are able to demonstrate that the iSCT PL is observed with a quantum yield estimated as a few 10-6 independently of the semiconducting or metallic nature of the outer tube. This result is mainly attributed to ultrafast exciton transfer from inner to outer tube. Furthermore, by carrying out PL excitation experiments on the (14,1)@(15,12) DWNT, we show that the iSCT PL can be detected through the optical excitation of the outer tube (Figure 1) indicating that the exciton transfer can also occur in the opposite way.References[1] D.I. Levshov et al., Phys Rev. B 96 (2017), pp. 195410

International audience; Measuring the orientation of a single fluorescent nanoemitter and obtaining emitters with a desired orientation is of highest importance for nanophotonics, especially in plasmonics where an emitting dipole close to a metallic surface will couple efficiently to plasmonic modes only if it is deposited vertically. Control of the orientation of a nano-object remains a challenge. Achieving vertical orientation, or having an information on the dipole orientation are key steps for efficient plasmonic excitation. We consider here cubic-shaped nanoplatelets with a thin CdSe core sandwiched in a thick CdS shell. By a combination of polarization measurement and radiation pattern Fourier analysis, we show that each single platelet behaves with excellent precision as a 2D dipole (sum of 2 orthogonal incoherent dipoles) and having only two possible orientations: either they lie horizontally on the substrate or they stand vertically on the edge. The cubic shape allows some platelets to deposit vertically so that they present a deterministic vertical dipole component.

International audience; Carbon nanotube/aluminum (CNT/Al) composites are prepared by a combination of flake powder metallurgy and hot-isostatic-pressing. The specimens are investigated by several techniques including Raman spectroscopy, optical microscopy, scanning- and transmission electron microscopy. The composites show a layered-microstructure with a stacking of CNT/Al flakes with a CNT-rich layer between two flakes. The individual Al grains forming the flakes are about 500 nm in size. The CNTs are well dispersed within a flake and they bridge the micro-cracks. The results reveal that the coefficient of thermal expansion (CTE) decreases markedly upon the increase in carbon content, reaching 15.4 x 10-6 K-1 for the specimen with a carbon content of 2.0 wt% (2.9 vol%), i.e. a 30% decrease compared to the CTE of pure Al. This could arise from the layered-microstructure resulting from the utilization of Al flakes as opposed to rounded particles.

International audience; The Red River, draining a 169,000 km(2) watershed, is the second largest river in Viet Nam and constitutes the main source of water for a large percentage of the population of North Viet Nam. Here we present the results of an investigation into the spatial distribution and temporal dynamics of particulate and dissolved organic carbon (POC and DOC, respectively) in the Red River Basin. POC concentrations ranged from 0.24 to 5.80 mg C L-1 and DOC concentrations ranged from 0.26 to 5.39 mg C L-1. The application of the Seneque/Riverstrahler model to monthly POC and DOC measurements showed that, in general, the model simulations of the temporal variations and spatial distribution of organic carbon (OC) concentration followed the observed trends. They also show the impact of high population densities (up to 994 inhab km(-2) in the delta area) on OC inputs in surface runoff from the different land use classes and from urban point sources. A budget of the main fluxes of OC in the whole river network, including diffuse inputs from soil leaching and runoff and point sources from urban centers, as well as algal net primary production and heterotrophic respiration was established using the model results. It shows the predominantly heterotrophic character of the river system and provides an estimate of CO2 emissions from the river of 330 Gg C year(-1). This value is in reasonable agreement with the few available direct measurements of CO2 fluxes in the downstream part of the river network.

International audience; Dye plants are present in the everyday life of many ethnic minority groups in Vietnam, ranging from meals, costumes to festivals. The study focuses on those within the Tay Nghe An Biosphere Reserve. This Biosphere Reserve covers an area of 1,303,285 ha of tropical rainforest, one of the 12 main types of ecosystem identified by UNESCO-MAB, in nine mountainous districts. Through our investigation, the use of 40 species of dye plants was recorded. They are mainly employed for dyeing food, textiles, and tools. Additional data about usage were also provided. In particular, one species (Dye Yam – Dioscorea cirrhosa) was recorded for the first time as a source of brown colorant for food. © 2023 International Society for Horticultural Science. All rights reserved.

Measuring electronic Raman scattering (ERS) has become an efficient method for structural characterization of metallic single-wall carbon nanotubes (SWCNT). However, applying this method to other types of SWCNT-based structures, e.g., those with strong van der Waals (VDW) coupling, is currently not well studied. In this work, we combine electron diffraction, Rayleigh and Raman spectroscopies to investigate the ERS process near 36 metallic transitions in 21 individual double-wall carbon nanotubes (DWCNTs) with all types of electronic configurations. We observe the partial suppression of ERS intensity in DWCNTs compared to SWCNTs and mainly attribute it to the effect of dielectric screening of Coulomb interactions. We probe ultra-pure macroscopic multi-chirality DWCNT solutions and identify the role of inhomogeneous broadening in observing ERS peaks in Raman spectra. Based on the experimental findings, we propose an adapted method for the structural identification of DWCNT samples from the ERS data. The obtained results can be generalized to the characterization of the emerging 1D VDW heterostructures based on metallic SWCNTs., DL thanks Prof. S. Rochal and D. Chalin for providing MAPLE code for calculating DWCNT transition energy shifts and W. Van Werveke and M. De Clercq for providing MATLAB code for creating chirality distribution maps. A part of the experimental data (i.e., microscopic Rayleigh and Raman spectra, ED patterns) was obtained and preliminary processed within the framework of Russian Foundation for Basic Research grant 18-32-00397 mol_a. Further data analysis (i.e., developing models for ERS, Raman and Rayleigh spectra fitting) was performed by DL with the support of the postdoctoral grant (12ZP720N) of the Fund for Scientific Research Flanders (FWO). The TEM measurements were performed in the Laboratorio de Microscopias Avanzadas (LMA), Universidad de Zaragoza (Spain). R.A. gratefully acknowledges the support from the Spanish MICINN (PID2019-104739 GB-100/AEI/10.13039/501100011033), Government of Aragon (projects DGA E13-20R (FEDER, EU)) and from the European Union H2020 program “ESTEEM3” (Grant number 823717). V.N.P. acknowledges financial support for NTB calculations from the National Science Fund of Bulgaria under grant KP-06-N38/10 from 06.12.2019. T.T.C acknowledges financial support from Vietnam Academy of Science and Technology (grant number: VAST03.06/22-23). H.N.T, E.F., A.A.Z, J.L.S. and M.P. acknowledge financial support by the ANR GAMBIT project, grant ANR-13-BS10-0014 of the French Agence Nationale de la Recherche. The characterization of the macroscopic UP-DWCNT samples was financially supported by a PhD fellowship for M. Erkens of the Research Foundation of Flanders (FWO, grant number: 11C9220N). D.L. acknowledges the financial support from the University of Antwerp Research Fund (grant BOF KP 43770). D.L., M.A., W.W. and S.C. also acknowledge funding from FWO projects (G040011N, G02112N, G035918N and G036618N).

International audience; The development of efficient bioremediation techniques to reduce aquatic pollutant load in natural sediment is one of the current challenges in ecological engineering. A nature-based solution for metal bioremediation is proposed through a combination of bioturbation and phytoremediation processes in experimental indoor microcosms. The invertebrates Tubifex tubifex (Oligochaeta Tubificidae) was used as an active ecological engineer for bioturbation enhancement. The riparian plant species Typha latifolia was selected for its efficiency in phyto-accumulating pollutants from sediment. Phytoremediation efficiency was estimated by using cadmium as a conservative pollutant known to bio-accumulate in plants, and initially introduced in the overlying water (20 μg Cd/L of cadmium nitrate – Cd(NO3)2·4H2O). Biological sediment reworking by invertebrates' activity was quantified using luminophores (inert particulates). Our results showed that bioturbation caused by tubificid worms' activity followed the bio-conveying transport model with a downward vertical velocity (V) of luminophores ranging from 16.7 ± 4.5 to 18.5 ± 3.9 cm·year− 1. The biotransport changed the granulometric properties of the surface sediments, and this natural process was still efficient under cadmium contamination. The highest value of Cd enrichment coefficient for plant roots was observed in subsurface sediment layer (below 1 cm to 5 cm depth) with tubificids addition. We demonstrated that biotransport changed the distribution of cadmium across the sediment column as well as it enhanced the pumping of this metal from the surface to the anoxic sediment layers, thereby increasing the bioaccumulation of cadmium in the root system of Typha latifolia. This therefore highlights the potential of bioturbation as a tool to be considered in future as integrated bioremediation strategies of metallic polluted sediment in aquatic ecosystems.

International audience; The main objective of this work is to process innovative bamboo flour (BF)-reinforced polymer composites.In this context, polyamide 11 (PA 11) is used as technical matrix. Moreover, BF is treated with tetraethyl orthosilicate (TEOS) playing the role of coupling agent. SEM observations show no influence of TEOS on the affinity. The composites were analysed by DSC and DMA, in comparison with neat PA 11. DSC analyses of PA 11/BF highlight that there is no significant modification of the percentage of crystallinity upon introduction of BF whatever the treatment is. Concerning the amorphous phase, only a slight shift of the glass transition of PA 11 from 35°C (PA 11) to 38°C (PA 11/BF composites) is recorded. This shift can be explained by physical bonds at the interface PA 11/BF. DMA analyses allow us to explore the role of BF fillers onto the properties of PA 11/BF composites. The first observation is a slight improvement of the shear modulus G0 when the concentration in TEOS increases. The b relaxation at -80°C is associated with the mobility of the complexes free amide groups/water molecules. There is no shift of the peak due to the presence of BF fillers. The magnitude and width of the relaxation increase with BF and also with TEOS treatment. These observations highlight the increase of hydrogen-bonded water in various sites of the vitreous state. The a relaxation is associated with the anelastic mobility liberated at the glass transition. For PA 11/BF composites, it is constituted by two components: the lower-temperature one due to neat polyamide and a higher-temperature one associated with PA 11/BF amorphous domains with a lower thermal conductivity

International audience; Organic fertilizer application is often touted as an economical and effective method to increase soil fertility. However, this amendment may increase dissolved organic carbon (DOC) runoff into downstream aquatic ecosystems and may consequently alter aquatic microbial community. We focused on understanding the effects of DOC runoff from soils amended with compost, vermicompost, or biochar on the aquatic microbial community of a tropical reservoir. Runoff collected from a series of rainfall simulations on soils amended with different organic fertilizers was incubated for 16 days in a series of 200 L mesocosms filled with water from a downstream reservoir. We applied 454 high throughput pyrosequencing for bacterial 16S rRNA genes to analyze microbial communities. After 16 days of incubation, the richness and evenness of the microbial communities present decreased in the mesocosms amended with any organic fertilizers, except for the evenness in the mesocosms amended with compost runoff. In contrast, they increased in the reservoir water control and soil-only amended mesocosms. Community structure was mainly affected by pH and DOC concentration. Compared to the autochthonous organic carbon produced during primary production, the addition of allochthonous DOC from these organic amendments seemed to exert a stronger effect on the communities over the period of incubation. While the Proteobacteria and Actinobacteria classes were positively associated with higher DOC concentration, the number of sequences representing key bacterial groups differed between mesocosms particularly between the biochar runoff addition and the compost or vermi-compost runoff additions. The genera of Propionibacterium spp. and Methylobacterium spp. were highly abundant in the compost runoff additions suggesting that they may represent sentinel species of complex organic carbon inputs. Overall, this work further underlines the importance of studying the off-site impacts of organic fertilizers as their impact on downstream aquatic systems is not negligible.

International audience; In this study, synthesized magnetite (Fe 3 O 4 ) nanoparticles were treated with a corrosion inhibitor, indole-3 butyric acid (IBA) and incorporated in an epoxy-polyamide coating. The coating was applied on a carbon steel substrate. For comparison, coatings with- out particles or with nontreated Fe 3 O 4 particles were also prepared. The IBA-modified nanomagnetite (IBA–Fe 3 O 4 ) was characterized by infrared spec- troscopy and Zeta potential measurements. The inhibitive action of IBA was shown by electrochemical measurements (polarization curves) performed for a bare carbon steel in 0.1 M NaCl solution containing Fe 3 O 4 or IBA–Fe 3 O 4 nanoparticles. Adherence and anticorrosion properties of the epoxy-based coatings containing Fe 3 O 4 or IBA–Fe 3 O 4 were compared to those of the pure epoxy-polyamide resin by dry and wet adherence measurements and by salt spray test. The results showed significant improvement of the film adherence and higher corrosion protection of the carbon steel in the presence of IBA–Fe 3 O 4 . It was concluded that the IBA effect was restricted to the metal/coating interface.

International audience; La qualité et sureté des aliments jouent un rôle important au Vietnam et dans la région de l'Asie du Sud Est. Dans son programme intégral, l'ASEAN met la sureté des aliments parmi des 12 priorités. Plusieurs travaux ont été focalises sur l'exploration de la biodiversité et des innovations technologiques en Asie du Sud Est afin d'améliorer la qualité et de gérer la sureté des aliments. C'est pour ces raisons, nous avons crée un réseau régional avec les soutiens des partenaires francophones et non-francophones en se basant sur les besoins de la région, l'expertise des partenaires et les coopérations étroites. Ce réseau est composé des 10 partenaires dynamiques et actifs provenant de la France, la Thaïlande, la Chine, et le Vietnam qui ont fait partie du Pre-projet de Coopération Scientifique Inter-universitaire PCSI http://pcsi2013.hust.edu.vn) de l'Agence Universitaire de la Francophonie (AUF) et le Laboratoire International Associe UB/AgroSup Dijon/HUST "Tropical Bioresources & Biotechnology"(www.umr-pam.fr/relation-internationale/tropical-bioresources-biotechnology.html). Notre présentation partagera nos expériences pour monter ce réseau a travers les régions et avec les partenaires francophones, souligner nos activités de recherche multidisciplinaires ainsi que notre point de vue vis-a-vis les interactions Nord-Sud et Sud-Sud. Nous allons aborder nos résultats issus de différents projets associes a ce réseau donc tels que la biodiversité des actinomycètes associes aux plantes médicinales, les bactéries lactiques dans les produits traditionnels fermentes du Vietnam et la valorisation de l'agriculture (riz, manioc) et leurs sous-produits par voies biologiques. (Résumé d'auteur)

International audience; The present work focuses on the use of layered double hydroxides (LDH) as containers for corrosion inhibitors in an epoxy coating. 2-Benzothiazolylthio-succinic acid (BTSA), used as corrosion inhibitor, was intercalated by co-precipitation in magnesium-aluminum layered double hydroxides. The obtained LDH-BTSA was characterized by infrared spectroscopy, X-ray diffraction and scanning electron microscopy. BTSA release from LDH-BTSA in NaCl solutions was investigated by UV-vis spectroscopy. The inhibitive action of LDH-BTSA on carbon steel corrosion was characterized by electrochemical methods and the protective properties of an epoxy coating containing LDH-BTSA were evaluated by electrochemical impedance spectroscopy. It was shown that the BTSA was intercalated in the layered double hydroxide and its loading was about 33%. The BTSA release was dependent on the NaCl concentration in the electrolyte. The polarization curves obtained on the carbon steel sample showed that the LDH-BTSA is an anodic inhibitor. Its efficiency was about 90% at a concentration of 3 g/l. The impedance results showed that the incorporation of LDH-BTSA (3%) in the epoxy matrix improved the corrosion protection of the carbon steel.

International audience; A convenient two step "one-pot " four-component synthetic approach was developed for the synthesis of new 6-arylated 5-hydroxy-benzo[a]phenazine derivatives using 2-hydroxy-1,4-naphthoquinone, a variety of aromatic aldehydes, benzene-1,2-diamine, and tetronic acid. In all cases, the synthesis proceeded via three key steps including condensation, Michael addition, and tautomerization. The structure of synthesized compounds was elucidated by spectral data. The inhibitory effect of newly synthesized compounds on nitric oxide (NO) production in lipopolysaccharide (LPS)- stimulated murine macrophage RAW 264.7 cells was assessed. All products exhibited the highly potential NO production inhibition activity with the IC50 values in the range of 3.68-12.14 mu M, indicating the critical role of these compounds in the development of potential anti-inflammation agents.

Laser dyes Rhodamine B and Perylene Red were incorporated at different relative concentrations into hybrid matrices synthesized using the sol–gel process. Energy transfer from Rhodamine B-donor to Perylene Red-acceptor molecules was observed. Using the different co-doped samples, solid-state dye laser systems were achieved with tuning band position control and increased efficiency with respect to the materials using solely one type of dye.

International audience; This paper presents observations of the F2-layer critical frequency (foF2) and height (hmF2) obtained at Phu Thuy (21.03°N, 105.95°E) and Bac Lieu (9.28°N, 105.73°E) observatories in Vietnam. The data have been examined for all seasons, during high and low solar activities, and compared with the foF2 and hmF2 of the International Reference Ionosphere model (IRI-2012, IRI-2016 two options: AMTB, SHU). Phu Thuy observatory is located at the Northern Crest of the EIA and Bac Lieu in the trough of the EIA, therefore the foF2 values at Phu Thuy are higher than at Bac Lieu. The results show that the IRI-2012 model estimates well the observed foF2 at both stations during high and low solar activities.During high solar activity, models estimate well the calculated hmF2 in summer for both stations. At Phu Thuy in equinoxes AMTB reproduces the night peak better than IRI-2012 and SHU, but higher and later about 2-3 hours, in winter the performance of AMTB is worst. At Bac Lieu, the IRI-2016 options reproduce the night peak and underestimates it, but IRI-2012 does not do it. The pre-noon peaks are underestimated by all the models, except IRI-2012 which overestimates the hmF2 pre-noon peaks at Bac Lieu. At Phu Thuy the pre-noon hmF2 peak is higher than the post-dusk one. At Bac Lieu the post-dusk peak is higher except in summer.During low solar activity, the IRI models estimate relatively well the shape of the calculated hmF2 at both stations. The IRI-2012 models explained better the observed foF2 (deviation of 2.5%) during solstices than during equinoxes (14.2%) for high solar activity. The IRI-2012 model explained better the observed foF2 in spring (7.8%) than in autumn (19.9%), matched better the calculated hmF2 in solstice (5.4%) than during equinoxes (11.8%).The performance of AMTB is worst at both stations for both the high and low solar activity periods except in autumn at Bac Lieu for the low solar year. IRI-2012 is best at the stations for both high and low solar activity periods, except in summer for the high solar activiy year when SHU is the best at Phu Thuy. These results can be used to improve the future IRI model.

International audience; We report the complete genome sequence of Tepidibacter sp. strain 8C15b, isolated from bank sediments of Haiphong Bay, Vietnam. The genome includes a 3,628,320-bp circular chromosome and a plasmid of 38,213 bp.

International audience; Although the structure and dynamics of planktonic viruses in freshwater and seawater environments are relatively well documented, little is known about the occurrence and activity of these viruses in estuaries, especially in the tropics. Viral abundance, life strategies, and morphotype distribution were examined in the Bach Dang Estuary (Vietnam) during the dry season in 2009. The abundance of both viruses and their prokaryotic hosts decreased significantly from upstream to downstream, probably as the result of nutrient dilution and osmotic stress faced by the freshwater communities. The antibiotic mitomycin-C revealed that the fraction of lysogenic cells was substantially higher in the lower seawater part of the estuary (max 27.1%) than in the upper freshwater area where no inducible lysogens were observed. The question of whether there is a massive, continuous induction of marine lysogens caused by the mixing with freshwater is considered. Conversely, the production of lytic viruses declined as salinity increased, indicating a spatial succession of viral life strategies in this tropical estuary. Icosahedral tailless viruses with capsids smaller than 60 nm dominated the viral assemblage throughout the estuary (63.0% to 72.1% of the total viral counts), and their distribution was positively correlated with that of viral lytic production. Interestingly, the gamma-proteobacteria explained a significant portion of the variance in the 90 nm) was explained by the beta-proteobacteria. Overall, these results support the view that the environment, through selection mechanisms, probably shapes the structure of the prokaryotic community. This might be in turn a source of selection for the virioplankton community via specific affiliation favoring particular morphotypes and life strategies.

Significant progress has been made in the last decade on the understanding of the role of the Coral and Solomon Seas as major suppliers of waters and chemical elements to the equatorial Pacific. Yet, the location, depth, and processes of chemical enrichment of these waters remain poorly constrained. Neodymium (Nd) isotopic compositions (εNd) and rare earth element concentrations (REE) are powerful tracers of land-ocean chemical exchanges. Combined, they can greatly refine the characterization of these exchanges. Here we report profiles of εNd at 21 stations located in the Coral and Solomon Seas as part of the GEOTRACES GP-12 cruise that complement the rare earth element concentration (REE) profiles of Pham (Chemical Geology, 2019, 524 (May), 11–36). Waters exiting the Solomon Sea are generally slightly more radiogenic than the incoming ones, suggesting inputs of radiogenic material along their pathways across the Solomon Sea. This radiogenic material is brought to the surface waters via natural processes (rivers, volcanic dusts) and likely local mining activities. Noticeable εNd increases are also observed in subsurface and intermediate layers. All these processes indicate the occurrence of local Boundary Exchange (BE) processes, which are estimated to occur within a few days. Coupling hydrological and chemical tracers allows highlighting the land-ocean interactions affecting some water layers and quantifying the exchanged fluxes of Nd. Modifications of the Nd concentration and isotopic composition in the lower thermocline layer require an external flux of 7.9 ± 2.0 t(Nd)/yr only partly balanced by a scavenging flux of 1.8 ± 2.3 t(Nd)/yr, leading to a net influx of 6.1 ± 1.7 t(Nd)/yr. Regarding the Upper Circumpolar Deep Water, a total net flux of 105 ± 50 t(Nd)/yr is estimated, the external flux is relatively high (86 ± 31 t(Nd)/yr while the scavenging flux remains. These results refine the role of the Solomon Sea as a supplier of continental chemical elements to the Pacific equatorial waters.

Transition metals are essential for a wealth of metabolic reactions, but their concentrations need to be tightly controlled across cells and cell compartments, as metal excess or imbalance has deleterious effects. Metal homeostasis is achieved by a combination of metal transport across membranes and metal binding to a variety of molecules. Gene duplication is a key process in evolution, as emergence of advantageous mutations on one of the copies can confer a new function. Here, we report that the poplar genome contains two paralogues encoding NRAMP3 metal transporters localized in tandem. All Populus species analyzed had two copies of NRAMP3, whereas only one could be identified in Salix species indicating that duplication occurred when the two genera separated. Both copies are under purifying selection and encode functional transporters, as shown by expression in the yeast heterologous expression system. However, genetic complementation revealed that only one of the paralogues has retained the original function in release of metals stored in the vacuole previously characterized in A. thaliana. Confocal imaging showed that the other copy has acquired a distinct localization to the Trans Golgi Network (TGN). Expression in poplar suggested that the copy of NRAMP3 localized on the TGN has a novel function in the control of cell-to-cell transport of manganese. This work provides a clear case of neo-functionalization through change in the subcellular localization of a metal transporter as well as evidence for the involvement of the secretory pathway in cell-to-cell transport of manganese.

International audience; Solar hydrogen generation via water splitting using a monolithic photoelectrochemical cell, also called artificial leaf, could be a powerful technology to accelerate the transition from fossil to sustainable energy sources. Identification of scalable methods for the fabrication of monolithic devices and gaining insights into their operating mode to identify solutions to improve performance and stability represent great challenges. Herein, we report on the one-step fabrication of a CoWO|ITO|3jn-a-Si|Steel| CoWS monolithic device via the simple photoinduced deposition of CoWO and CoWS as oxygen evolution reaction (OER) and onto an illuminated ITO|3jn-a-Si|Steel solar cell using a singledeposition bath containing the [Co(WS4)2]2- complex. In a pH 7 phosphate buffer solution, the best device achieved a solar-to-hydrogen conversion yield of 1.9%. Evolution of the catalyst layers and that of the 3jn-a-Si light-harvesting core during the operation of the monolithic device are examined by conventional tools such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES) together with a bipotentiostat measurement. We demonstrate that the device performance degrades due to the partial dissolution of the catalyst. Still, this degradation is healable by simply adding [Co(WS4)2]2- to the operating solution. However, modifications on the protecting indium-doped tin oxide (ITO) layer are shown to initiate irreversible degradation of the 3jn-a-Si light-harvesting core, resulting in a 10-fold decrease of the performances of the monolithic device.

International audience; Atmospheric Non-Thermal Plasma (ANTP) technology for indoor air treatment has the disadvantage to produce undesirable by-products such as ozone and NOx. To overcome the by-products formation and increasing energy efficiency, ANTP could take advantage of its synergetic effect through combination with heterogeneous catalysts. Various catalysts based on Ag, Au, Cu, Co, Mn, La (supported on OMS-2, Al2O3 or CeO2) and Nb has been investigated with and without a dielectric barrier discharge (DBD). In the absence of catalysts, the toluene removal efficiency was about 60% with O3, CO, CO2, and NOx as reaction products. Without plasma, the reaction of toluene conversion over Al2O3, OMS-2, and perovskite based catalysts are promoted only at high temperature (200-400°C). When the plasma was combined to catalyst at room temperature, the toluene removal efficiency strongly increased when the catalysts are in the discharge region. Best results, up to 96% toluene conversion, were obtained when using 1wt%Au/Al2O3 or Nb2O5 catalysts. The products of the toluene oxidation were CO and CO2.

International audience; Despite the well-known potential of earthworms to modify soil macroporosity , water infiltration through their burrowing activities, it is still difficult to predict which species are more effective in increasing water infiltration. We thus investigated the relationships between soil water infiltration, burrow network properties, morphology and anatomy of a diversity of earthworm species. We sampled 23 earthworm species in northern Vietnam and measured 16 morpho-anatomical traits a priori linked to their feeding, vertical distribution or burrowing behaviour. One individual was then incubated in a repacked soil core for four weeks under laboratory conditions, each in four replicates. After incubation, burrow network properties were assessed using X-ray computed tomography , soil saturated hydraulic conductivity was measured using the falling head method. We found large differences among species belonging to similar or different ecological categories in their effect on soil saturated hydraulic conductivity. We observed neutral to positive effects with an increase of up to 30-fold compared to cores without earthworms. The effect of earthworms on soil hydraulic conductivity was well pre-dicted by burrow network properties (volume and continuity of burrows) or morpho-anatomical traits (body weight, circular and longitudinal muscles thickness) using the random forest regression models (R2 > 0.95 in both cases). Earthworms with a large body weight and circular and longitudinal muscle thicknesses have the highest probability of increasing soil saturated hydraulic conductivity compared to other species. In addition, we showed from the coinertia analysis that body weight and circular and longitudinal muscle thickness were positively associated with the volume and continuity of burrows. Our findings therefore illustrate the power of employing a trait-based approach to predict the effect of non-Lumbricidae earthworms on water infiltration in comparison to the classical ecological category approach. Such trait information could be used to prioritize practices that favour the expression of more desirable earthworm traits to increase soil water infiltration.

International audience; During many past decades, scientists from various countries have studied separately the atmospheric motions in the lower atmosphere, in the Earth's magnetic field, in the magnetospheric currents, etc. All of these separate studies lead today to the global study of the Sun and Earth connections, and as a consequence, new scientific programs (IHY- International Heliophysical Year, CAWSES- Climate and Weather in the Sun-Earth System) are defined, in order to assume this new challenge. In the past, many scientists did not have the possibility to collect data at the same time in the various latitude and longitude sectors. Now, with the progress of geophysical sciences in many developing countries, it is possible to have access to worldwide data sets. This paper presents the particularities of geophysical parameters measured by the Vietnamese instrument networks. It introduces a cooperative Vietnamese-IGRGEA (International Geophysical Research Group Europe Africa) project, and presents, for the first time, to the international community, the geophysical context of Vietnam. Concerning the ionosphere: since 1963, during four solar cycles, the ionosonde at Phu Thuy (North Vietnam) was operating. The Phu Thuy data exhibits the common features for the ionospheric parameters, previously observed in other longitude and latitude sectors. The critical frequencies of the E, F1 and F2 ionospheric layers follow the variation of the sunspot cycle. F2 and E critical frequencies also exhibit an annual variation. The first maps of TEC made with data from GPS receivers recently installed in Vietnam illustrate the regional equatorial pattern, i.e. two maxima of electronic density at 15 N and 15 S from the magnetic equator and a trough of density at the magnetic equator. These features illustrate the equatorial fountain effect. Concerning the Earth's magnetic field: a strong amplitude of the equatorial electrojet was first observed by the CHAMP satellite at the height of 400 km in the Vietnamese longitude sector. In this paper we compare the ground magnetic observations of the Indian and Vietnamese magnetometer networks. This comparison highlights the regional structure of the amplitude of the equatorial electrojet, which is stronger in Vietnam than in India. Concerning the monsoon: Vietnam exhibits a strong monsoon and has mainly one rainy season peaking in August, hence associated with the southwest monsoon flow. But some monsoon variability from one place to another is related to the orography. In the mountainous northern regions of Vietnam, there is an "early" monsoon peaking in July. In the coastal regions between 12 N and 19 N the monsoon season is centered on October. Concerning lightning: Vietnam is a country of strong atmospheric storms with some areas of very intense lightning in North Vietnam (22,5 N, 105 E) and in South Vietnam (11 N, 107 E). In North Vietnam strong lightning is associated with the most intense rainy region. Keywords. Ionosphere (Electric fields and currents) - Meteorology and dynamics (Tropical meteorology) - Geomagnetism and paleomagnetism (Time variations, diurnal to secular)

International audience; Laser effects have been obtained with dye-doped hybrid xerogel samples prepared several years ago and stored in different "classical" conditions. Firstly, using the same configuration of the laser cavity as was used 4-5 years ago, we have obtained almost identical laser performances, and slope conversion efficiencies were measured up to 80% and operational lifetimes, with 1-mJ initial output energy and 10-Hz repetition rate of several hundred thousand pulses obtained. Secondly, we have introduced the new pyrromethene 605 dye into a hybrid xerogel matrix and obtained good laser performances similar to the rest of the pyrromethene family

International audience; A low-profile circularly polarized (CP) antenna for a handheld Ultra-High Frequency RadioFrequency Identification (UHF RFID) reader is proposed in this paper. The radiating part on the topsubstrate is composed of three inverted-F elements rotated 120◦around the center of the structure. Apower splitting circuit, placed on the bottom substrate, based on a series transmission line feed deliversequal amplitude to the three IFAs with a sequential 120◦phase shift. Both layers are fabricated onlow-cost FR4 material. This design has a disk form factor with a compact size of 35 mm circle radiusand an 8.6 mm height. The measurement shows good results withS11as lower than−10 dB for thewhole band, 3 dB-axial ratio around 110◦(10 MHz of bandwidth), directivity reaching 4.4 dBic, and thetotal gain of the antenna is 1.9 dBic. In order to validate the proposed antenna performance, a UHFRFID handheld reader is built based on the ThingMagic M6E-Nano module. Different scenarios areinvestigated to validate the proposed antenna performance in a real environment

International audience; Multitemporal synthetic aperture radar (SAR) interferometry (InSAR) is a widely used technique to measure the ground subsidence and has already shown its ability to map such phenomena on a large spatial scale with millimetric accuracy from space. In Vietnam, to have independent SAR data for surface risk applications, a new X-band SAR mission (JV-LOTUSat) has been scheduled for launch for the 2019-2020 timeframe. However, Vietnam is located in tropical regions where their conditions are impacted by strong atmosphere. The aim of this article is to provide a better understanding of the capabilities of the X-band for estimating the ground subsidence under tropical atmospheric conditions. Analysis is carried out on two stacks, TerraSAR-X and Cosmos SkyMed X-band, from 2011 to 2014 in Ha Noi. We show that the results on the ground subsidence from InSAR processing can describe consistently the subsidence area based on ground measurements. This article demonstrates that the InSAR technique can be effective at detecting and estimating the subsidence phenomena even with the X-band and under conditions typical of tropical regions. The displacement results from TerraSAR-X and Cosmos SkyMed datasets are consistent, with a correlation coefficient (R2) of 0.91 for the period during which their coverage overlaps. Groundwater overexploitation is one of the main causes of the ground subsidence in Ha Noi. This study provides strong support for the scientific potential of the X-band SAR space-borne mission in Vietnam and other tropical countries because it demonstrates the feasibility of the ground subsidence estimates by the X-band SAR, even in conditions impacted by strong atmosphere.

International audience; As flood events are expected to become more frequent due to climate change, investigating how overland flow exports terrestrial nutrients, carbon and living organisms into aquatic systems is essential for understanding both soil and stream ecosystem status. Here we assessed how dissolved organic carbon (DOC), total suspended sediments (TSS), and stream bacterial diversity responded to stream discharge and overland flow during stormflow in a tropical catchment. A higher humification index and a decreasing ratio of allochthonous to autochthonous DOC indicated that DOC from soils was exported to stream during the flood. The delta C-13 and delta N-15 of particulate matter was indicative of a source in the cultivated areas of the upper catchment and of subsurface soils (stream banks and gullies) in the downstream section. Bacterial richness of particle-attached (PA) and the free-living (FL) fractions increased with the flood progression in the upstream section. Moreover, the community structure of the PA fraction in the stream was more similar to that of overland flow than was the FL fraction. This suggests that the soil PA bacterial community was washed-out with overland flow during the flood recession. The relative contribution of sources and the composition of TSS, rather than hydrological regime, significantly drove the composition of bacterial community. In conclusion, our results emphasize that overland flow during a flood event strongly influences the structure of stream bacterial communities further underlining the biological connectivity between terrestrial runoff and stream flow.

International audience; The present environmental crisis prompts the search for renewable energy sources such as solar-driven production of hydrogen from water. Herein, we report an efficient hybrid photocatalyst for water oxidation, consisting of a ruthenium polypyridyl complex covalently grafted on core/shell Fe@FeOx nanoparticles via a phosphonic acid group. The photoelectrochemical measurements were performed under 1 sun illumination in 1 M KOH. The photocurrent density of this hybrid photoanode reached 20 μA/cm2 (applied potential of +1.0 V vs reversible hydrogen electrode), corresponding to a turnover frequency of 0.02 s–1. This performance represents a 9-fold enhancement of that achieved with a mixture of Fe@FeOx nanoparticles and a linker-free ruthenium polypyridyl photosensitizer. This increase in performance could be attributed to a more efficient electron transfer between the ruthenium photosensitizer and the Fe@FeOx catalyst as a consequence of the covalent link between these two species through the phosphonate pendant group.

International audience; The influence of Fe addition on thermal stability, crystallography, and magnetic properties of τ-Mn51Al47C2 was investigated. Alloys with composition Mn51-xFexAl47C2 (x = 0, 0.5, 1, 2, and 4) were synthesized by mechanical alloying method. High purity of τ-Mn(Fe)AlC up to 98% could be obtained after 10 h of milling, then annealed at 1050 °C for 1 h, and followed by an aging process at appropriate temperatures from 515 to 540 °C for 50 min. It was found that the thermal stability of both ε and τ phases was enhanced by the addition of Fe up to 4 at.% into MnAlC alloy through a shifting of ε-to-τ transformation temperature to high temperature region and a reduction in c/a ratio of Fe doped τ-MnAlC compared to iron free τ-MnAlC. While the magnetization and Curie temperature of Fe doped τ-MnAlC showed a reduction compared to iron free τ-Mn51Al47C2, coercivity seems not to be significantly affected. Ab initio calculation showed a lower magnetic moment of Fe (μFe = 1.77 μB) compared to Mn (μMn_average = 2.36 μB) in τ-Mn(Fe)AlC when Fe substituted Mn position at 1a site.

A new racemic xanthone, garmckeanin A (1), and eight known analogs 2-9 were isolated from the ethyl acetate (AcOEt) extract of the Vietnamese Garcinia mckeaniana leaves. Their structures were determined by MS and NMR spectral analyses and compared with the literature. The AcOEt extract showed good cytotoxicity against cancer cell lines KB, Lu, Hep-G2 and MCF7, with IC50 values of 5.40-8.76 μg/mL, and it also possessed α-glucosidase inhibitory activity, with an IC50 value of 9.17 μg/mL. Garmckeanin A (1) exhibited inhibition of all cancer cell lines, with an IC50 value of 7.3-0.9 μM. Allanxanthone C (5) successfully controlled KB growth, with an IC50 value of 0.54 μM, higher than that of the positive control, ellipticine (IC50 1.22 μM). Norathyriol (8) was a promising α-glucosidase inhibitor, with an IC50 value of 0.07 μM, much higher than that of the positive control, acarbose (IC50 161.0 μM). The interactions of the potential α-glucosidase inhibitors with the C- and N-terminal domains of human intestinal α-glucosidase were also investigated by molecular docking study. The results indicated that bannaxanthone D (2), garcinone E (4), bannaxanthone E (6), and norathyriol (8) exhibit higher binding affinity to the C-terminal than to the N-terminal domain through essential residues in the active sites. In particular, compound 8 could be assumed to be the most potent mixed inhibitor.

Fucoidans are sulfated, fucose-rich marine polysaccharides primarily found in cell walls of brown seaweeds (macroalgae). Fucoidans are known to possess beneficial bioactivities depending on their structure and sulfation degree. Here, we report the first functional characterization and the first crystal structure of a prokaryotic sulfatase, PsFucS1, belonging to sulfatase subfamily S1_13, able to release sulfate from fucoidan oligosaccharides. PsFucS1 was identified in the genome of a Pseudoalteromonas sp. isolated from sea cucumber gut. PsFucS1 (57 kDa) is Ca2+ dependent and has an unusually high optimal temperature (68 °C) and thermostability. Further, the PsFucS1 displays a unique quaternary hexameric structure comprising a tight trimeric dimer complex. The structural data imply that this hexamer formation results from an uncommon interaction of each PsFucS1 monomer that is oriented perpendicular to the common dimer interface (~ 1500 Å2) that can be found in analogous sulfatases. The uncommon interaction involves interfacing (1246 Å2) through a bundle of α-helices in the N-terminal domain to form a trimeric ring structure. The high thermostability may be related to this unusual quaternary hexameric structure formation that is suggested to represent a novel protein thermostabilization mechanism.

Off the coast of Vietnam, two recent events seem to have contributed to the death of coral reefs: the rapid invasion of a small marine snail called Drupella, and the emergence of a disease that spreads over corals. We decided to investigate whether there is a link between the corals, the snails, and the disease. We analyzed the mucus covering the surface of corals, both in healthy corals and those infested by Drupella snails. Mucus produced by corals is usually full of helpful microbes, protecting the corals from harmful microbes that can make them ill or kill them. Our analyses showed that, when Drupella eats corals, the snail also removes one of the corals’ primary defenses by eliminating most of the tiny protectors in their mucus. This allows harmful microbes to cause additional damage to the corals.

The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here, we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in the southern South China Sea: the Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters. We used a set of variables derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter and four mesozooplankton size fractions to identify changes in the nitrogen source and TP of mesozooplankton across these habitats. We found clear indications of a shift in N sources for biological production from nitrate in near‐coastal waters with shallow mixed layer depths toward an increase in diazotroph‐N inputs in oceanic waters with deep mixed layer depths where diazotrophs shaped the phytoplankton community. The N source shift was accompanied by a lengthening of the food chain (increase in the TP). This may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ15N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, a high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels., Plain Language Summary: Zooplankton are one of the central pillars of the marine food web and form an important link between the production of organic matter by phytoplankton and biomass at higher trophic levels (e.g., fish). Of particular interest are mesozooplankton (0.2–20 mm in size), which encompass a diverse assemblage of animals utilizing a range of feeding strategies, including herbivory, omnivory, and carnivory. Since mass and energy are lost with each trophic step, their prevailing feeding strategy determines the availability of mass and energy to the upper food web. The exact relationship between carnivores and herbivores in mesozooplankton has so far only been studied with complex experiments or in homogenous environments. We have now resolved zooplankton feeding relationships in a highly dynamic marine environment. Specifically, we used stable nitrogen isotopes in amino acids and bulk organic matter in combination with a habitat‐delineating method for phytoplankton to directly determine the ratio of carnivores to herbivores in zooplankton from dynamic habitats in the South China Sea. The mass and energy transfer across trophic levels is less efficient in such variable marine environments compared to stable open ocean systems. These findings represent a big step toward understanding the dynamics of planktonic food webs in general., Key Points: Trophic structure of mesozooplankton is regulated by similar environmental factors such as phytoplankton assemblages. Diazotrophy and nutrient availability correlated with enhanced mesozooplankton carnivory in a complex tropical marine ecosystem. Mass and energy transfer across trophic levels of planktonic food webs are less efficient in spatially and temporally variable ecosystems., Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659, National Foundation for Science and Technology Development (NAFOSTED) http://dx.doi.org/10.13039/100007224, National Aeronautics and Space Administration (NASA) http://dx.doi.org/10.13039/100000104, Schmidt Ocean Institute, National Science Foundation (NSF) http://dx.doi.org/10.13039/100000001, https://doi.org/10.5061/dryad.bk3j9kdbv

International audience; The Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) is the causal agent of the coronavirus disease 2019 (COVID-19) pandemic. To date, viruses closely related to SARS-CoV-2 have been reported in four bat species: Rhinolophus acuminatus, Rhinolophus affinis, Rhinolophus malayanus, and Rhinolophus shameli. Here, we analysed 343 sequences of the mitochondrial cytochrome c oxidase subunit 1 gene (CO1) from georeferenced bats of the four Rhinolophus species identified as reservoirs of viruses closely related to SARS-CoV-2. Haplotype networks were constructed in order to investigate patterns of genetic diversity among bat populations of Southeast Asia and China. No strong geographic structure was found for the four Rhinolophus species, suggesting high dispersal capacity. The ecological niche of bat viruses closely related to SARS-CoV-2 was predicted using the four localities in which bat viruses were recently discovered and the localities where bats showed the same CO1 haplotypes than virus-positive bats. The ecological niche of bat viruses related to SARS-CoV was deduced from the localities where bat viruses were previously detected. The results show that the ecological niche of bat viruses related to SARS-CoV2 includes several regions of mainland Southeast Asia whereas the ecological niche of bat viruses related to SARS-CoV is mainly restricted to China. In agreement with these results, human populations in Laos, Vietnam, Cambodia, and Thailand appear to be much less affected by the COVID-19 pandemic than other countries of Southeast Asia. In the climatic transitional zone between the two ecological niches (southern Yunnan, northern Laos, northern Vietnam), genomic recombination between highly divergent viruses is more likely to occur. Considering the limited data and the risk of recombinant bat-CoVs emergence as the source of new pandemics in humans, the bat populations in these regions should be under surveillance.

International audience; A new green method for trace level quantification of four herbicides, glyphosate (GLYP), glufosinate (GLUF), and their main metabolites, aminomethylphosphonic acid (AMPA) and 3-(methyl-phosphinico)propionic acid (MPPA), was developed. The purification step without any derivatization was conducted by solid-phase extraction using Chelex-100 resin in the Fe (III) form, followed by elution with 5% NH4OH. The four analytes were quantified by ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The developed extraction method was validated on five fresh and sea water matrices with mean recoveries ranging from 80.1% to 109.4% (relative standard deviation < 20%). The extraction conditions were evaluated and certified for the high applicability of the extraction method too. The limits of detection (ng/L) in the five water matrices were in ranges 0.70 - 4.0, 2.4 - 3.9, 1.8 - 4.7, and 1.6 - 4.0 for GLYP, AMPA, GLUF, and MPPA, respectively. The method was successfully applied to detect the four compounds in surface waters sampled along the Red River Delta region in July 2019. The highest concentrations were detected at 565, 1,330, 234, and 871 ng/L for GLYP, AMPA, GLUF, and MPPA, respectively. These results showed the potential capacity of this new method for convenient monitoring of herbicides and their metabolites in the diverse natural water system.