Programming the assembly of carboxylic acid-functionalised hybrid polyoxometalates

We report here the straightforward synthesis and characterisation of a series Anderson-type hybrid polyoxometalates in high yield, functionalised with carboxylic acid following the reaction of anhydride precursors with the starting hybrid cluster ([n-N(C4H9)4]3[MnMo6O18((OCH2)3CNH2)2]). Seven new structures have been obtained, five of which have acid-terminated ligands. Six of these structures have been isolated with a yield higher than 80% with high purity. This reaction is limited by the bulkiness of the anhydride used; this effect can be employed to selectively synthesise one isomer out of three other possibilities. The acid groups and aromatic platforms attached to the clusters can act as building tools to bridge several length scales and engineer molecular packing within the crystal structure. The presence of acids should also change the hydrophilicity of the clusters, and therefore the way they interact with hydrophilic surfaces. We also show a potential relationship between the acid group interaction in the packing diagram and the cluster’s tendency to interact with a hydrophilic surface. In addition to reporting a derived synthetic path to new acid-terminated Mn-Anderson-type hybrids, we describe here a new way to program self-assembly motifs of these compounds in the crystal structure and at interfaces

Chemical Composition and in Vitro Evaluation of the Antioxidant and Antimicrobial Activities of Eucalyptus gillii Essential Oil and Extracts

In this study, essential oil and various extracts (hexane, petroleum ether, acetone, ethanol, methanol and water) of Eucalyptus gilii were screened for their chemical composition, antimicrobial and antioxidant activities. The essential oil chemical composition was analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID), respectively. Thirty four compounds were identified, corresponding to 99.5% of the total essential oil. Tannins [104.9-251.3 g catechin equivalent (CE)/Kg dry mass], flavonoids [3.3-34.3 g quercetin equivalent (QE)/Kg dry mass], phenolics [4.7-216.6 g gallic acid equivalent (GAE)/Kg dry mass] and anthocyannins [1.2-45.3 mg cyanidin-3-glucoside equivalent (C3GE)/Kg dry mass] of various extracts were investigated. Free radical scavenging capacity of all samples was determinedt. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, the IC50 of essential oil was 163.5 ± 10.7 mg/L and in the 2,2'-azinobis-3-ethylbenzothiazoline-6-sulphonate (ABTS) assay, it was 94.7 ± 7.1 mg/L. Among the various extracts, the water extract showed the best result (IC50 = 11.4 ± 0.6 mg/L) in the DPPH assay which was comparable to vitamin C (IC50 = 4.4 ± 0.2 mg/L). The antimicrobial activities were evaluated against different bacterial and fungal strains. Gram positive bacteria were found to be more sensitive to the essential oil and extracts than Gram negative ones. Anthocyanins seem to have a major effect on the growth of Bacillus subtilis (R2 = 0.79). A significant antifungal activity was observed against the yeast and fungi. Correlations between chemical composition and antioxidant activities were studied and R2 values were about 0.96 for the effect of phenolics on the DPPH assay

Preliminary investigations of prey pursuit and capture by king penguins at sea

Prey pursuit and capture by king penguins (Aptenodytes patagonicus) were investigated with multiple data recorders in the Crozet Archipelago during the 1995/96 austral summer. Birds were fitted with a swim speed and depth data logger that sampled every second making possible fine-scale analyses of underwater behavior. Data were obtained for two birds for periods of 2.5 and 2.9 days, respectively. During each dive deeper than 30m, the swimming speed was constant at around 2m/s, defined as "cruising" speed. However, steep acceleration events ("dashes") were observed. These dashes occurred in "U", "W" and "Plateau" shaped dives. Based on their shape, these dashes were separated into "Rushes" (28% of all dash events) where penguins moved upward and increased their speed from the cruising speed; "Adjusts" (59%) where penguins swam also upward and increased their speed to return to cruising speed after a short slow-down, and "Intermediates" (13%) which were "Adjusts" events that briefly overshot the cruising speed. "Rushes" mainly occurred at the bottom phase of deep dives. They were followed by other dash events in 80% of cases. Moreover, "Rushes" lasted longer and the distance traveled during them was bigger compared to other dash events. "Adjusts" events were observed at the bottom phase and early part of the ascent phase. They were single events within a dive in 50% of cases. These results suggested that dashes, especially "Rushes" may be the main pursuit and capturing behavior performed by king penguins on patchily distributed preys in water deeper than 100m

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Développement d'une méthode de décontamination active des sédiments portuaires pollués en tributylétain par électromigration

Legislation for dredged material is becoming more severe. Remediation strategies for pollutants and organotin compounds more specifically are becoming a very important issue. This is particularly the case for tributyltin (TBT) due to its high toxicity. Different methods for remediation of polluted sediments exist. Some are based on natural attenuation phenomenons which are often long and limited to some pollutants, while others stabilize and confine the pollution by chemical or thermal treatment. The use of electroremediation for dredge sediments is a novel approach which has been applied to contaminated soils. This innovative technology for sediments has only received few applications at the pilot or industrial stage on an international basis. The basic principle of the electro remediation is to exploit the migration of ionic species under the effect of an electric field between one or more cathodes and one or more anodes located in a porous medium. The main phenomena for remediation are: electromigration, for ionic species, to the corresponding electrode (to the cathode for cations, to the anode for anions) and electroosmosis, for uncharged species, mostly to the cathode. The effectiveness of electroremediation is controlled by the flow of pollutants in the soil solution, their transport velocity and their concentration in the liquid phase. Thus, optimization of the processes depends simultaneously on electrochemical factors that control the transport of pollutants and on physical and chemical factors that influence the matter transfer. In this thesis, several experiments were conducted on a solid matrix model and on a real sediment to study the effect of decontamination of theses matrices under electroremediation. The matrices were a model contaminated sediment (TBT spiked kaolin) and severely contaminated sediment. Decontamination experiments were performed under various conditions of pH and potential electrical gradient. These conditions were also applied to contaminated sediments. Results for the decontamination of sediments show that a TBT reduction level better than 90 % can be obtained for the solid matrix model, TBT spiked kaolin, and can reach up to 70 % reduction for natural sediment. They also show that the compounds preferentially move to the cathode. We have identified the competition between two mechanisms: transfer / transport of butyltin to the electrodes and transport of reactive which help the in-situ degradation of these species. This work has demonstrated very promising results for the active degradation of TBT at pilot stage. They offer a promising alternative for the active remediation of contaminated sediments from dredging operations.Avec une législation devenant de plus en plus stricte concernant les sédiments de dragages, la décontamination des polluants et plus particulièrement, à cause de leur forte toxicité, des composés organostanniques, notamment le tributylétain (TBT) représente un enjeu très important. Différents procédés de décontamination des sédiments pollués existent. Certains reposent sur les phénomènes d'atténuation naturelle souvent longs et limités à certains polluants, tandis que d'autres consistent à stabiliser et confiner la pollution par voie chimique ou thermique. L'électrodécontamination est une technique innovante qui n'a encore reçu que peu d'applications au stade pilote ou sur le terrain au plan international. Le principe de base de ce procédé consiste à exploiter le déplacement d'espèces ioniques polluantes sous l'effet d'un champ électrique entre une ou plusieurs cathodes et une ou plusieurs anodes implantées dans un milieu poreux. D'une manière simplifiée, la dépollution qui s'effectue essentiellement par électromigration pour les espèces ioniques (métaux libres...) vers l'électrode correspondante (cathode pour les cations et anode pour les anions) et par électroosmose pour les espèces neutres (composés organiques ou organométalliques neutres...) le plus souvent vers la cathode. Son efficacité est contrôlée par le flux de polluants dans la solution du sol donc par leur vitesse de transport et de leur concentration dans la phase liquide. L'optimisation du procédé dépend donc simultanément de facteurs électrochimiques qui contrôlent le transport des polluants et de facteurs physico-chimiques qui influencent le transfert de matière. Plusieurs expériences ont été menées sur un modèle de matrice solide (kaolinite dopée en tributylétain (TBT)) et sous diverses conditions de pH et de gradient de potentiel. Des essais ont été également réalisés sur un sédiment naturel avec diverses conditions opératoires concernant le pH, le gradient de potentiel et la température. Les résultats montrent que nous obtenons des pourcentages d'abattements en TBT supérieurs à 90 % pour un modèle de matrice solide, la kaolinite dopée en TBT, et peuvent atteindre jusqu'à 70 % d'abattement pour un sédiment naturel. Ils montrent également que les composés migrent préférentiellement vers la cathode. Les résultats obtenus ont permis de mettre en évidence la compétition entre deux mécanismes : le transfert / transport des composés butylés de l'étain vers les électrodes et le transport du réactif facilitant la dégradation in-situ de ces espèces. Les travaux ont montré des résultats très satisfaisants et extrêmement prometteurs quant à l'application du procédé au stade pilote. Ils ont ouverts une voie particulièrement intéressante sur la décontamination des sédiments et leur gestion future

Développement d'une méthode de décontamination active des sédiments portuaires pollués en tributylétain par électromigration.

Avec une législation devenant de plus en plus stricte concernant les sédiments de dragages, la décontamination des polluants et plus particulièrement, à cause de leur forte toxicité, des composés organostanniques, notamment le tributylétain (TBT) représente un enjeu très important. Différents procédés de décontamination des sédiments pollués existent. Certains reposent sur les phénomènes d atténuation naturelle souvent longs et limités à certains polluants, tandis que d autres consistent à stabiliser et confiner la pollution par voie chimique ou thermique. L'électrodécontamination est une technique innovante qui n'a encore reçu que peu d'applications au stade pilote ou sur le terrain au plan international. Le principe de base de ce procédé consiste à exploiter le déplacement d espèces ioniques polluantes sous l effet d un champ électrique entre une ou plusieurs cathodes et une ou plusieurs anodes implantées dans un milieu poreux. D une manière simplifiée, la dépollution qui s'effectue essentiellement par électromigration pour les espèces ioniques (métaux libres...) vers l'électrode correspondante (cathode pour les cations et anode pour les anions) et par électroosmose pour les espèces neutres (composés organiques ou organométalliques neutres ) le plus souvent vers la cathode. Son efficacité est contrôlée par le flux de polluants dans la solution du sol donc par leur vitesse de transport et de leur concentration dans la phase liquide. L optimisation du procédé dépend donc simultanément de facteurs électrochimiques qui contrôlent le transport des polluants et de facteurs physico-chimiques qui influencent le transfert de matière. Plusieurs expériences ont été menées sur un modèle de matrice solide (kaolinite dopée en tributylétain (TBT)) et sous diverses conditions de pH et de gradient de potentiel. Des essais ont été également réalisés sur un sédiment naturel avec diverses conditions opératoires concernant le pH, le gradient de potentiel et la température. Les résultats montrent que nous obtenons des pourcentages d abattements en TBT supérieurs à 90 % pour un modèle de matrice solide, la kaolinite dopée en TBT, et peuvent atteindre jusqu à 70 % d abattement pour un sédiment naturel. Ils montrent également que les composés migrent préférentiellement vers la cathode. Les résultats obtenus ont permis de mettre en évidence la compétition entre deux mécanismes : le transfert / transport des composés butylés de l étain vers les électrodes et le transport du réactif facilitant la dégradation in-situ de ces espèces. Les travaux ont montré des résultats très satisfaisants et extrêmement prometteurs quant à l application du procédé au stade pilote. Ils ont ouverts une voie particulièrement intéressante sur la décontamination des sédiments et leur gestion future.Legislation for dredge material is becoming more severe. Remediation strategies for pollutants and organotin compounds more specifically are becoming a very important issue. This is particularly the case for tributyltin (TBT) due to its high toxicity. Different methods for remediation of polluted sediments exist. Some are based on natural attenuation phenomenons which are often long and limited to some pollutants, while others stabilize and confine the pollution by chemical or thermal treatment. The use of electroremediation for dredge sediments is a novel approach which has been applied to contaminated soils. This innovative technology for sediments has only received few applications at the pilot or industrial stage on an international basis. The basic principle of the electro remediation is to exploit the migration of ionic species under the effect of an electric field between one or more cathodes and one or more anodes located in a porous medium. The main phenomena for remediation are: electromigration, for ionic species, to the corresponding electrode (to the cathode for cations, to the anode for anions) and electroosmosis, for uncharged species, mostly to the cathode. The effectiveness of electroremediation is controlled by the flow of pollutants in the soil solution, their transport velocity and their concentration in the liquid phase. Thus, optimization of the processes depends simultaneously on electrochemical factors that control the transport of pollutants and on physical and chemical factors that influence the matter transfer. In this thesis, several experiments were conducted on a solid matrix model and on a real sediment to study the effect of decontamination of theses matrices under electroremediation. The matrices were a model contaminated sediment (TBT spiked kaolin) and severely contaminated sediment. Decontamination experiments were performed under various conditions of pH and potential electrical gradient. These conditions were also applied to contaminated sediments. Results for the decontamination of sediments show that a TBT reduction level better than 90 % can be obtained for the solid matrix model, TBT spiked kaolin, and can reach up to 70 % reduction for natural sediment. They also show that the compounds preferentially move to the cathode. We have identified the competition between two mechanisms: transfer / transport of butyltin to the electrodes and transport of reactive which help the in-situ degradation of these species. This work has demonstrated very promising results for the active degradation of TBT at pilot stage. They offer a promising alternative for the active remediation of contaminated sediments from dredging operations.PAU-BU Sciences (644452103) / SudocSudocFranceF

Influence of building maintenance, environmental factors, and seasons on airborne contaminants of swine confinement buildings

Eight swine confinement buildings, selected to cover the widest possible range of cleanliness, were visited twice during winter and once during summer to verify the range, seasonal variations, and correlations between biological and chemical contaminants. Physical aspects were graded for dirtiness (1 = clean, 10 = dirty), ventilation, air temperature, number of animals, building, and room size. Air samples were taken to measure relative humidity, CO2, ammonia, total dust, and microbiological counts and/or identification (bacteria and molds); endotoxin levels also were measured. During winter, average measurements and ranges were: CO2 = 0.304% (0.254 to 0.349%); ammonia = 19.6 ppm (1.9 to 25.9 ppm); dust = 3.54 mg/m3 (2.15 to 5.60 mg/m3). There were 883 cfu/m3 (547 to 2862 cfu/m3) of molds, 4.25 x 10(5) cfu/m3 (1.67 x 10(5) to 9.30 x 10(5) cfu/m3) of total bacteria, 29 cfu/m3 (3 to 94 cfu/m3) of thermophilic actinomycetes). A significant decrease in bacterial levels (p = 0.04), dust (p = 0.0008), ammonia (p = 0.005), and CO2 (p < 0.0001) was observed during summer sampling when compared with winter levels. Mold counts were positively correlated (p = 0.03) with dirtiness scores, while bacterial counts were negatively correlated with this parameter (p < 0.002), whereas bacteria and endotoxins were correlated with the number of animals (p < 0.05). Ambient gases (CO2 and ammonia) correlated with each other (p = 0.006). Bacteria were the most important contaminant in swine confinement buildings, and endotoxin levels found were also very high (mean = 4.9 x 10(3) EU/m3). We conclude that a wide range of air contamination exists in swine confinement buildings of different maintenance. There is a decrease in some of these contaminants during summer. Observed dirtiness of the swine confinement buildings has a poor predictive value concerning air quality