Search results for "Sorption"
showing 10 items of 4623 documents
Polymeric Nanoparticles with Neglectable Protein Corona
2020
Small : nano micro 16(18), 1907574 (2020). doi:10.1002/smll.201907574
A dual channel sulphur-containing a macrocycle functionalised BODIPY probe for the detection of Hg(II) in a mixed aqueous solution
2018
We report herein the synthesis and chromo-fluorogenic behaviour of a new probe 1 containing a boron-dipirromethene (BODIPY) unit electronically connected with a dithia-dioxa-aza macrocycle. Acetonitrile and water-acetonitrile 95:5 v/v solutions of the probe showed an ICT band in the visible zone and are nearly non-emissive. When acetonitrile was used as solvent, addition of Hg(II) and trivalent metal cations induced an hypsochromic shift of the absorption band and moderate emission enhancements. A highly selective response was obtained when using competitive media such as wateracetonitrile 95:5 v/v. In this case only Hg(II) induced a hypsochromic shift of the absorption band and a marked em…
Influence de la symétrie et de la taille de la molécule adsorbée sur le processus d'adsorption des composés éthyléniques sur une zéolithe de topologi…
2005
This manuscript lies within the scope of the understanding of the stepped isotherm observed during adsorption, on MFI zeolites, of some organic compounds which have a similar size to that of the pore opening of zeolite. During this work, the process of adsorption of ethylene and tetramethylethylene is initially studied by gravimetry and then by in situ infrared spectroscopy. This last technique enables to follow simultaneously the modifications of the adsorbent and the adsorbate. The analysis of these data lets suppose that the step in adsorption isotherm can be explained by taking account simultaneously of the symmetry and the size of the admolecule. In addition to the infrared bands chara…
Negative thermal expansion in cuprite-type compounds: A combined synchrotron XRPD, EXAFS, and computational study of Cu2O and Ag2O
2006
Cuprite-type oxides (Cu2O and Ag2O) are framework structures composed by two interpenetrated networks of metal-sharing M4O tetrahedra (M = Cu, Ag). Both compounds exhibit a peculiar negative thermal expansion (NTE) behaviour over an extended temperature range (9 240 K for Cu2O, 30-470 K for Ag2O). High-accuracy synchrotron powder diffraction and EXAFS measurements were performed from 10 K up to the decomposition temperature to understand the nature of the NTE effects. The critical comparison of the diffraction and absorption results concerning the temperature dependence of the interatomic distances and of the atomic vibrational parameters proves to be fundamental in defining the local dynam…
Multiple scattering approach for two-electron resonant emission studied by angle-resolved coincidence spectroscopy.
2008
International audience; We have developed a generalization of the multiple-scattering formalism to deal with Auger-photoelectron coincidence spectroscopy APECS in the solid state. We have merged the exact atomic treatment of the angular correlations between the two electrons and the single-particle approach, on which the multiplescattering description of condensed matter relies. This allows the recovering, even in extended systems, of the entangled form of the electron-pair wave function characterizing the coincidence angular diffraction pattern. In the atomic limit our formalism correctly reproduces the cross section, as calculated within the statistical-tensors approach, usually employed …
Decorated pottery study: Analysis of pigments by x-ray absorbance spectroscopy measurements
2007
Characterization of pigments on decorated pottery fragments has been fully carried out by nondestructive x-ray absorbance spectroscopy (XAS). The samples were a series of pottery shards excavated from the archeological site of Caltagirone (Sicily, Italy), a well-known ceramic production center. Aesthetical criteria and morphological observations allowed us to attribute the samples to quite different historical periods, starting from the 18th century B.C. up to the 16th century A.D. An extensive time interval led us to suppose that different materials and techniques were used for the production of the ceramic paste and also for the preparation of pigments. XAS measurements were performed at …
Improved bioaccessibility and antioxidant capacity of olive leaf ( Olea europaea L.) polyphenols through biosorption on Saccharomyces cerevisiae
2016
Abstract Olive ( Olea europaea L.) leaves (OL) are natural by-products that can be used as an advantageous rich source of bioactive compounds, especially polyphenols. This study investigated the potential use of Saccharomyces cerevisiae as a new carrier of OL antioxidants and a means to protect their bioactivity during simulated gastrointestinal digestion. The biosorption on S. cerevisiae allowed the recovery of 25.17 mg/g and 49.40% of the polyphenols from olive leaf (var. Chemlali ) infusions. Both infusions and suspensions before and after biosorption were analyzed for total soluble polyphenols and total antioxidant capacity (oxygen radical absorbance capacity (ORAC) and trolox equivalen…
A mathematical approach to model diffusion properties of sedimentary rocks relevant to Sicily cultural heritage
2007
Cultural heritage vestiges represent complex physical systems, able to interact with the environment through continuous exchanges of heat and fluids (water, air). In this wide context, particular relevance is assumed by transport phenomena and diffusion of pollutant, vehiculated inside the considered structure by water itself. Interaction mechanisms can be considered at various observation scales, depending on the material provenance and on its geometry and location. Involved materials are commonly constituted by porous rocks - more or less altered - belonging to geological sedimentary formations, as limestone, calcarenite and travertine. Their appreciable porosity affects significantly liq…
H-He collision-induced satellite in the Lyman alpha profile of DBA white dwarf stars
2020
The spectra of helium-dominated white dwarf stars with hydrogen in their atmosphere present a distinctive broad feature centered around 1160~\AA\/ in the blue wing of the Lyman-$\alpha$ line. It is extremely apparent in WD 1425+540 recently observed with HST COS. With new theoretical line profiles based on ab initio atomic interaction potentials we show that this feature is a signature of a collision-induced satellite due to an asymptotically forbidden transition. This quasi-molecular spectral satellite is crucial to understanding the asymmetrical shape of Lyman-$\alpha$ seen in this and other white dwarf spectra. Our previous work predicting this absorption feature was limited by molecular…
<title>Hardening in LiF, induced by fast Kr and Ni ions, and recovery of the structure and properties under annealing</title>
2005
The recovery of optical and mechanical properties of LiF crystals irradiated with 790 MeV 78Kr and 640 MeV 58Ni ions at 10l2 ions/cm2 under annealing at temperatures up to 810 K is investigated. The optical absorbance and depth profiles of hardness before and after annealing were measured. A marked recovery of hardness and change in the optical absorption spectra were observed at temperatures above 520-530 K. An activation energy of 0.15±0.02eV, which is close to that for the thermal migration of H centers, is obtained from the annealing data. The results indicate a significant role of the H-center aggregates in the hardening and annealing processes. The maximum hardening is created and the…