Search results for "nuclear chemistry"
showing 10 items of 1124 documents
Sorption kinetic of aroma compounds by edible bio-based films from marine-by product macromolecules: Effect of relative humidity conditions
2019
International audience; Edible films based on gelatin and chitosan have high gas and aroma barrier properties. This study focused on their capability to sorbed/retain aroma compounds (1-hexanal, 2-hexen-1-ol, 1-hexanol, 3-hexanone and phenol) at three relative humidity level (≤2%, 53% or 84% RH). Whatever the relative humidity condition, the order of sorption is keton (3-hexanone) < aldehyde (1-hexanal) < aliphatic alcohols (2-hexen-1-ol and 1-hexanol) < phenol. This order could be related to the intrinsic chemical properties of aroma compounds. The increase in moisture enhanced the sorption at the highest RH for all the aroma compounds. However, a competition between water and aliphatic al…
Physicochemical investigation of acrylamide solubilization in sodium bis(2-ethylhexyl)sulfosuccinate and lecithin reversed micelles.
2003
The state of acrylamide confined within dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and lecithin reversed micelles dispersed in CCl4 has been investigated by FTIR and H-1 NMR spectroscopy. Measurements have been performed at 25 degreesC as a function of the acrylamide-to-surfactant molar ratio (R) at a fixed surfactant concentration (0.1 mol kg(-1)). The analysis of experimental data, corroborated by the results of SAXS measurements, is consistent with the hypothesis that acrylamide is quite uniformly distributed among reversed micelles mainly located in proximity to the surfactant head-group region and that its presence induces significant unidimensional growth of micellar aggregates.…
Spectroscopic analyses of the influence of electron beam irradiation doses on mechanical, transport properties and microstructure of chitosan-fish ge…
2015
International audience; The objective of this work was to better display the effect of electron beam accelerator doses (0, 20, 40 and 60 kGy) on structural, mechanical and barrier properties of edible lightly plasticized chitosan-fish gelatin blend film. From Electron Spin Resonance (ESR), signal at 3500 G for blend film was identified as free radical formation during irradiation, which might introduce intermolecular cross-linking into the polymer matrix, thus affecting structural properties. Tensile Strength (TS) for gelatin film significantly increased with growing irradiation doses (improved by 30% for 60 kGy), but the TS of chitosan and blend films were not significantly affected. On th…
Coupling tyrosol, quercetin or ferulic acid and electron beam irradiation to cross-link chitosan–gelatin films: A structure–function approach
2015
International audience; Marine industry by-products, chitosan and fish gelatin, entrapping natural antioxidants (ferulic acid, quercetin and tyrosol) were used to prepare edible active films by casting. The films were composed of chitosan and fish gelatin (1:1 w:w) and incorporating antioxidants (∼50 mg/g). After solvent evaporation (drying), the films were irradiated at 60 kGy by electron beam. This treatment aims at investigating the coupled effect of irradiation with the presence of active compound on the structure and functional properties of the films. Electron Spin Resonance (ESR) unravelled free radical formation during irradiation in films containing ferulic acid or tyrosol which fa…
The Effects of Different Formulation of Baking Powder on Short Biscuits Characteristics
2011
Chemical leaveners are used to give cookies, cakes, and other baked goods their characteristic textures. They produce gas when a carbon dioxide source and an acid are mixed together and come into contact with water. The most common sources of gas are sodium or potassium bicarbonate alone or in combination with ammonium bicarbonate. A great variety of acids are used in baking powder formulations. The acid are classified according to their capacity to react at lower or elevated temperature as rapid or slow acting. The aim of these study is to evaluate a very rapid acting acid (tartaric acid) and a slow to very slow acting acid (sodium acid pyrophosphate - SAPP) on the characteristics of short…
Application of Potassium Ion Impregnated Titanium Dioxide as Nanocatalyst for Transesterification of Linseed Oil
2018
The current work comprises the investigation of biodiesel production from linseed oil using TiO2 and a potassium L-tartrate monobasic (C4H5KO6)-modified TiO2 nanocatalyst. Different amounts of C4H5KO6 were considered for TiO2 modification. The nanocatalyst TiO2–0.5C4H5KO6 (1:0.5 molar ratio) showed the best conversion rate for biodiesel production. The nanocatalyst was characterized by FTIR, XRD, TEM, BET, and XPS, and the Hammett indicator–benzenecarboxylic acid titration method was used for basicity measurement. The biodiesel was characterized by GC-MS and 1H and 13C NMR. Furthermore, the optimum reaction parameters for transesterification reaction were analyzed, and the yield was determi…
Preliminary magnetic resonance relaxometric analysis of Fricke gel dosimeters produced with polyvinyl alcohol and glutaraldehyde
2017
This work describes the preliminary analysis of Fricke gels dosimeters characterized by a new formulation making use of a matrix of polyvinyl alcohol cross-linked by adding glutaraldehyde and analyzed by means of nuclear magnetic resonance relaxometry. In previous optical studies, these gels have shown promising dosimetric features in terms of photon sensitivity and low diffusion of ferric ions produced after irradiation. In this work, we used a portable nuclear magnetic resonance relaxometer to measure the relaxation times (which are important for dosimetric applications) of these gel materials. For this purpose, we performed a study for optimizing the acquisition parameters with a nuclear…
Silver nanoparticles in resin luting cements: antibacterial and physiochemical properties
2016
Background Silver has a long history of use in medicine as an antimicrobial and anti-inflammatory agent. Silver nanoparticles (NAg) offer the possibility to control the formation oral biofilms through the use of nanoparticles with biocidal, anti-adhesive, and delivery abilities. This study aims to evaluate the antibacterial effect of resin luting cements with and without NAg, and their influence on color, sorption and solubility. Material and methods NAg were incorporated to two dual-cured resin cements (RelyX ARC (RA) color A1 and RelyX U200 (RU) color A2) in two concentrations (0.05% and 0.07%, in weight), obtaining six experimental groups. Disc specimens (1x6mm) were obtained to verify t…
Mesoporous silica microparticles gated with a bulky azo derivative for the controlled release of dyes/drugs in colon.
2018
[EN] Mesoporous silica microparticles were prepared, loaded with the dye safranin O (M-Saf) or with the drug budesonide (M-Bud) and capped by the grafting of a bulky azo derivative. Cargo release from M-Saf at different pH values (mimicking those found in the gastrointestinal tract) in the absence or presence of sodium dithionite (a reducing agent mimicking azoreductase enzyme present in the colon) was tested. Negligible safranin O release was observed at pH 6.8 and 4.5, whereas a moderate delivery at pH 1.2 was noted and attributed to the hydrolysis of the urea bond that linked the azo derivative onto the external surface of the inorganic scaffold. Moreover, a marked release was observed w…
Speciation and interactions of plutonium with humic substances and kaolinite in aquifer systems
2007
Abstract The speciation of plutonium (Pu) in contact with humic substances (HS) and kaolinite has been performed in aquifer systems. Mainly the redox behavior, complexation, and sorption of plutonium are discussed here. The redox behavior of Pu(VI) in contact with HS was studied and it was found that Pu(VI) is reduced to Pu(III) and Pu(IV) within a couple of weeks. The complexation constants (log β LC ) of Pu(III) and Pu(IV) with HS have been determined by means of the ultrafiltration method. Furthermore, the sorption of Pu(III) and Pu(IV) onto kaolinite has been investigated as a function of pH by batch experiments under aerobic and anaerobic conditions.