Éditeur(s) : Université des Antilles AREBio Groupe de recherche BIOSPHERES : BIOlogie, Sciences Physiques & Humaines pour les énergies Renouvelables, l
Extrait de : 1er colloque international BIOSPHERES, du 18 au 20 juin 2019. Université des Antilles
Description : The Chemical Purification, analysis and Screening core laboratories (CPAS) are located at the University of South Florida campus in Tampa. This core offers instrumentation and expertise in fractionation, purification, and various chemical analyses to support synthetic and natural products drug discovery research groups. Our main equipment are dedicated to chromatographic separation and purification (MPLC, HPLC) and mass-spectrometry for analytic detection, quantification and identification (LC-MS SQ, QqQ and QToF). The CPAS services also include Circular Dichroism spectrometry, general spectroscopic characterization (UV, FTIR), lyophilization (bench top and high capacity freeze-dryers), synthesis (microwave reactor), ADME screening (permeability and drug solubility testing), and high-throughput screening development capability (automated liquid handler and multimode plate reader). An example of three significant studies will be presented at the conference to illustrate the CPAS core facility services: 1) Identification of new bioactive compounds from mangrove endophytic fungi as potential alternatives to malaria drug resistance, 2) Myricanol isolated from Bayberry (Myrica Cerifera) and its synthetic derivatives targeting the microtubuleassociated protein tau accumulation in the Alzheimer's disease and 3) New ent-labdane diterpenes with solid tumor cell lines antiproliferative properties from the endemic plant Eupatorium obtusissmum from the island of Hispaniola. The core provides research lab training workshops in advanced technology and assistance so users can operate any instruments available in the laboratories to successfully accomplish their analyses and research projects.

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Permalien : http://www.manioc.org/fichiers/V19063
V19063

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : International audience
Separated olivine grains from a deeply subducted serpentinized wehrlite (Changawuzi in the western Tianshan ultrahigh-pressure belt, China) were analysed with unpolarized transmission FTIR and the Ti contents were determined using LA-ICP-MS. The major bands in the olivine spectra display striking similarities to Ti-clinohumite and are interpreted as OH in lamellae. The quantification of the water content in lamellae requires calibration of the IR-absorption for such bands. We have obtained a new absorption coefficient for Ti-clinohumite of 0.125+/−0.017 ppm cm2 based on polarized FTIR measurements on three orthogonal sections through a large single crystal of Ti-clinohumite from Val Malenco, which has a known water content of 1.53 wt%. The resulting water content in olivine using this calibration factor ranges from 440 to 2,600 ppm and correlates positively with the Ti content that ranges from 130 to 1,400 ppm. For the quantification of the water content in Ti-chondrodite and Ti-clinohumite that are associated with olivine, we developed a new method using attenuated total reflectance FTIR spectroscopy. Ti-chondrodite and Ti-clinohumite display similar IR bands at ~3,562, 3,525 and ~3,583–3,586 cm−1. As in olivine, the water content and Ti content correlate in both Ti-clinohumite and Ti-chondrodite, indicating an intergrowth of these minerals, which has been confirmed by TEM analyses. Our results confirm previous suggestions that there is a strong correlation between the Ti content of ultramafic rocks and their capacity to transport water to the deeper mantle in subduction zones beyond conditions where hydrous phases are stable.
ISSN: 0010-7999

hal-01172237
https://hal.archives-ouvertes.fr/hal-01172237
DOI : 10.1007/s00410-014-0992-8

Éditeur(s) : HAL CCSD Elsevier
Résumé : The uppermost mantle in back arc regions is the site of complex interactions between partial melting, melt percolation, and fluid migration. To constrain these interactions and evaluate their consequences on geochemical cycles, we carried out an in situ trace element and water study of a suite of spinel peridotite xenoliths from two regions of the Japan back arc system, Ichinomegata (NE Japan) and Oki-Dogo (SW Japan), using LA-ICPMS and FTIR spectrometry, respectively. This study provides the first full dataset of trace element and hydrogen compositions in peridotites including analyses of all their main constitutive silicate minerals: olivine, orthopyroxene and clinopyroxene. The Ichinomegata peridotites sample a LREE-depleted refractory mantle (Mg# olivine = 0.90; Cr# spinel = 0.07–0.23; Yb clinopyroxene = 7.8–13.3 × C1-chondrite, and La/Yb clinopyroxene = 0.003–0.086 × C1-chondrite), characterized by Th-U positive anomalies and constant values of Nb/Ta. The composition of the studied Ichinomegata samples is consistent with that of an oceanic mantle lithosphere affected by cryptic metasomatic interactions with hydrous/aqueous fluids (crypto-hydrous metasomatism). In contrast, the Oki-Dogo peridotites have low Mg# olivine (0.86–0.93) and a broad range of compositions with clinopyroxene showing “spoon-shaped” to flat, and LREE-enriched patterns. They are also characterized by their homogeneous compositions in the most incompatible LILE (e.g., Rb clinopyroxene = 0.01–0.05 × primitive mantle) and HFSE (e.g., Nb clinopyroxene = 0.01–2.16 × primitive mantle). This characteristic is interpreted as resulting from various degrees of melting and extensive melt-rock interactions. FTIR spectroscopy shows that olivine in both Ichinomegata and Oki-Dogo samples has low water contents ranging from 2 to 7 ppm wt. H2O. In contrast, the water contents of pyroxenes from Ichinomegata peridotites (113–271 ppm wt. H2O for orthopyroxene, and 292–347 ppm wt. H2O for clinopyroxene) are significantly higher than in Oki-Dogo peridotites (9–35 ppm wt. H2O for orthopyroxene, and 15–98 ppm wt. H2O for clinopyroxene). This indicates a relationship between melt-rock interaction and water concentrations in pyroxenes. Our study suggests that the water content of the Japan mantle wedge is controlled by the late melt/fluid/rock interactions evidenced by trace element geochemistry: a mechanism triggered by magma-rock interactions may have acted as an efficient dehydrating process in the Oki-Dogo region while the Ichinomegata mantle water content is controlled by slab-derived crypto-hydrous metasomatism.
ISSN: 0016-7037

hal-01553105
https://hal.archives-ouvertes.fr/hal-01553105
DOI : 10.1016/j.gca.2017.03.042

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The kinetics of hydrogenation of dry iron-bearing olivine single crystals was determined by performing hydration experiments under hydrothermal conditions at high pressure. The experiments were performed in a multi-anvil press at 3 GPa, for a temperature range between 900 and 1200 °C and for various durations. The oxygen fugacity was buffered along Ni-NiO joint. Polarized Fourier transform infrared spectroscopy and recent empirical calibration were used to quantify the hydroxyl distributions in the samples along crystallographic axes after the experiments. The chemical diffusion coefficients are similar (barely slower) than in olivine hydrated at lower pressure (0.2 and 0.3 GPa) for the same diffusion mechanism. Under the given experimental conditions, the anisotropy of diffusion is the same as for proton-vacancy mechanism, with diffusion along the [0 0 1] axis faster than along the [1 0 0]. However, the anisotropy at 3 GPa is weaker compared to measurements at lower pressures and the analysis of concentration profiles using 3D models shows that an isotropic solution could also be relevant. Fits of the diffusion data to an Arrhenius law yield activation energies for the slightly faster [0 0 1] axis of the crystallographic axes around 198 ± 5 kJ mol−1, a value only slightly lower than the results from previous experimental studies for natural iron-bearing olivine hydrogenated at lower confining pressure. At 3 GPa, hydrogenation can be well approximated by a single mechanism controlled by coupled diffusion of protons and octahedral vacancies (di- and tri-valent ions). The diffusion rates are fast enough to alter hydrogen concentration within olivine in xenoliths ascending from the mantle or experiencing hydrogen-rich metasomatism events, but too slow to permit complete homogenization of hydrogen in olivine-rich rocks at kilometer scale in less than one My.
ISSN: 0031-9201

hal-01412663
https://hal.archives-ouvertes.fr/hal-01412663
DOI : 10.1016/j.pepi.2016.08.005

Éditeur(s) : HAL CCSD Elsevier
Résumé : We have studied the phase transformation of forsterite to wadsleyite under shear stress at the Earth's transition zone pressure and temperature conditions. Two-step experiments were performed using a multi-anvil press. First, we hot pressed iron-free forsterite at 6 or 11 GPa and 1100 degrees C. Then we deformed a slab of this starting material using a direct simple shear assembly at 16 GPa and 1400 degrees C for 1, 15, 35, 40, or 60 min. Both the starting material and the deformed samples were characterized using optical and scanning electron microscopy including measurements of crystal preferred orientations (CPO) by electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR). The phase transformation occurs very rapidly, in less than 1 min, and metastable forsterite relics are not observed after deformation. The grain size of wadsleyite is slightly smaller than the forsterite starting material. The water contents obtained from FTIR analyses in forsterite and wadsleyite are 65-124 wt ppm H2O and 114-736 wt ppm H2O, respectively, which are well below water solubility at similar conditions in the presence of free water. Wadsleyite aggregates display weak CPO patterns with [1 0 0] axes concentrated at low angle to the shear direction, [0 1 0] axes perpendicular to the shear plane and nearly random [0 0 1] axes. Only a few dislocations were observed in wadsleyite with TEM. This observation is consistent with the assumption that most dislocations formed during the initial high-stress stages of these stress-relaxation experiments, were consumed in the phase transformation, probably enhancing the transformation rate. CPO patterns vary as a function of the water content: with increasing water content the density of [1 0 0] axes parallel to the shear direction decreases, and the density of [0 0 1] axes increases. Viscoplastic self-consistent modeling of CPO evolution using previously reported glide systems for wadsleyite, i.e., [1 0 0]{0 k 1} and 1/2 (1 1 1){1 0 1}, cannot reproduce the measured CPO, unless the [0 0 1](0 1 0) system, for which dislocations have not been observed by TEM, is also activated. In addition, wadsleyite grain growth suggests the participation of diffusion-assisted processes in deformation. Calculated anisotropies for P and S-waves using measured CPO are always below 1%. This very low anisotropy is due to both the low finite strain achieved in the experiments, which leads to weak wadsleyite CPO, and to the diluting effect of added majorite. The present experiments emphasize the importance of stress, grain size evolution and water content in the forsterite to wadsleyite phase transformation and subsequent deformation in the transition zone.
ISSN: 0031-9201

hal-00617430
https://hal.archives-ouvertes.fr/hal-00617430
DOI : 10.1016/j.pepi.2010.11.001

Éditeur(s) : HAL CCSD Springer/Terra Scientific Publishing Company
Résumé : International audience
Titanian clinohumite is an accessory phase found in peridotites, and it can be a key repository of volatile and other trace elements in sub-arc mantle. To characterize spectroscopic variations due to volatile elements in the phase, we have investigated the infrared spectroscopic characteristics of a suite of naturally occurring Ti clinohumite minerals with varying F and Ti concentrations. Samples were ultramafic rocks from Cerro del Almirez, Spain and Cima di Gagnone, Switzerland. The infrared spectra corresponding to OH vibrations showed systematic variation in regard to the abundance of F in Ti clinohumite. In particular, the intensity ratios of infrared absorption spectra at 3,565 and 3,390 cm-1 correlated linearly with the abundance of F independently of the crystal orientation. Raman spectra did not corroborate the Fourier transform infrared (FTIR) results. This intensity ratio provides an alternative analytical criterion for the characterization of Ti clinohumite.
ISSN: 1343-8832

hal-01133685
https://hal.archives-ouvertes.fr/hal-01133685
DOI : 10.1186/1880-5981-66-60

Éditeur(s) : HAL CCSD ACS American Chemical Society - Publications
Résumé : International audience
ABSTRACT: In this paper, the structural, optical and thermal properties of n-type (100),p-type (100) and (111) mesoporous silicon (MePSi) are reported. The mesoporous silicon wasprepared by an electrochemical process from bulk silicon wafer. Depending on the etchingdepth, analyses show that the porosity of p-type (111) increased by 32 to 40% compared to p(100) which, in turn, increased by 22 to 48% compared to n-type (100). The structuremorphology and the abundance of Si-Ox and Si-Hy also depended heavily on the type andcrystal orientation of MePSi. The thermal properties of the MePSi layers such as thermalconductivity (κ), volumetric heat capacity (ρCp) and thermal contact resistance (Rth) weredetermined using the pulsed photothermal method. The thermal conductivity of bulk silicondropped sharply after etching, decreasing by more than twenty-fold in the case of n-type (100)and by over forty-five fold for p-type (100) and (111). According to the percolation modeldepending on both porosity and phonon confinement, the drop in thermal conductivity wasmainly due to the nanostructure formation after etching. Thermal investigations showed thatthe volumetric heat capacity (ρCp) followed the barycentric model which depends mainly onthe porosity. The thermal contact resistances of MePSi layers were estimated to be in therange of 1x10-8 to 1x10-7 K⋅m2⋅W-1.
The Journal of Physical Chemistry C

hal-01495490
https://hal.archives-ouvertes.fr/hal-01495490
DOI : 10.1021/acs.jpcc.6b13101

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
The effect of trace concentrations of Ti on the rate and mechanism of hydrogen diffusion in pure forsterite was investigated experimentally. Forsterite doped with 350–400 ppm Ti (predominantly octahedral Ti3+, minor tetrahedral Ti4+) was prepared by diffusing Ti into pure synthetic forsterite at high temperature (1500 °C), very low oxygen fugacity (~QFM-5) at atmospheric pressure. The Ti-doped forsterite was then diffusively hydroxylated in a piston-cylinder apparatus at much lower temperatures (650–1000 °C) and higher oxygen fugacities, at 1.5–2.5 GPa, with chemical activities buffered by forsterite-enstatite or forsterite-periclase and partial pressure of H2O equal to total pressure. This produced hydrogen concentration-distance profiles of several hundred micrometers in length. Diffusion of hydrogen through the Ti-doped forsterite, even at very high Embedded Image , does not lead to redox re-equilibration of the high Ti3+/ΣTi ratio set during the synthesis of the starting material at extremely reducing conditions—the metastable point defects are partially preserved.Three main hydroxylated point defects are observed; hydroxyl is associated with Ti4+ (titano-clinohumite point defects), Ti3+ (and possibly other trivalent cations), and M-site vacancies. Concentration-distance profiles represent an interplay between diffusion and reaction (i.e., site rearrangement) to form the observed point defects. In all experiments, the concentration-distance profiles of the hydroxylated Ti defects coincide with the concentration-distance profiles of the M-site vacancy substitution, with the same crystallographic anisotropy. This suggests that the macroscopic movement of hydrogen through the crystal is due to one diffusion mechanism (the diffusion of hydroxylated M-site vacancies). The net H diffusion coefficient [logD(ΣH)], between 650–1000 °C, is Embedded Image where the values of logD0(ΣH) parallel to [100] and [001] directions are −3.0 ± 0.4 and −2.2 ± 0.4, respectively; diffusion is therefore around one order of magnitude faster along the c axis than along the a axis. The diffusion of hydrogen is slightly faster in Ti-doped forsterite than in pure forsterite. There is no effect of chemical activity or oxygen fugacity on the rate of diffusion. Hydrogen diffusion profiles represent a complex interplay between the movement of H through the crystal lattice and point-defect reactions to maintain charge balance.
ISSN: 0003-004X

hal-01467402
https://hal.archives-ouvertes.fr/hal-01467402
DOI : 10.2138/am-2016-55681571

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Four fibers from banana-trees (leaf, trunk) and coconut-tree (husk, fabric) were examined before their incorporation in cementitious matrices, in order to prepare insulating material for construction. Their botanical compositions have been determined following a method described previously. Thermal degradation of these fibers were studied between 200 and 700 °C under nitrogen gas flow. Temperature of pyrolysis was the experimental parameter investigated. The solid residues obtained were analyzed by classical elemental analysis, Fourier Transform Infra Red (FTIR) spectroscopy and were observed by Scanning Electron Microscopy (SEM). This study has shown (1) the relation between botanical, chemical composition with both localization of fibers in the tree and type of tree; (2) the rapid and preferential decomposition of banana fibers with increasing temperature of pyrolysis and (3) the rough samples are made of hollow fibers.
ISSN: 0960-8524

hal-00809780
https://hal.univ-antilles.fr/hal-00809780
DOI : 10.1016/j.biortech.2005.11.030

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
Crystallization experiments were conducted at 200 MPa to determine the effect of small amounts of H2O on the liquidus temperature of basaltic melts in which plagioclase is the liquidus phase. The H2O concentrations in the quenched glasses, determined by infrared spectroscopy and Karl-Fischer titration, ranged from 0.02 to 4.2 wt% H2O. The dry liquidus temperature at 200 MPa was estimated from experiments at 1 atm (H2O-free) and from the known pressure dependence of plagioclase crystallization temperature. The effect of water (expressed as wt% H2O) on the plagioclase liquidus temperature is nonlinear and diminishing with increasing melt H2O concentrations. According to our new experimental data, it can be empirically predicted with following equation: Formula where CH2O is the water concentration in the melt (wt%), TDRY, and TWET are plagioclase crystallization temperatures in water-free and water-bearing systems, respectively. The relationship between CH2O and liquidus temperature worked out in this study is valid for a range of basaltic compositions, ranging from high-alumina basalts to basaltic andesites. The combination of the empirical equation predicting the liquidus depression of plagioclase with previous models predicting the olivine liquidus curve is useful to determine the liquidus temperature in various H2O-bearing basaltic systems in which either plagioclase or olivine is the liquidus phase.
ISSN: 0003-004X

hal-00757600
https://hal.archives-ouvertes.fr/hal-00757600
DOI : 10.2138/am.2012.4100