Modern microwave methods in solid state inorganic materials chemistry: from fundamentals to manufacturing

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Evaluation of extra-virgin olive oils shelf life using an electronic tongue-chemometric approach

Physicochemical quality parameters, olfactory and gustatoryretronasal positive sensations of extra-virgin olive oils vary during storage leading to a decrease in the overall quality. Olive oil quality decline may prevent the compliance of olive oil quality with labeling and significantly reduce shelf life, resulting in important economic losses and negatively condition the consumer confidence. The feasibility of applying an electronic tongue to assess olive oils usual commercial light storage conditions and storage time was evaluated and compared with the discrimination potential of physicochemical or positive olfactory/gustatory sensorial parameters. Linear discriminant models, based on subsets of 58 electronic tongue sensor signals, selected by the meta-heuristic simulated annealing variable selection algorithm, allowed the correct classification of olive oils according to the light exposition conditions and/or storage time (sensitivities and specificities for leave-one-out cross-validation: 8296 %). The predictive performance of the E-tongue approach was further evaluated using an external independent dataset selected using the KennardStone algorithm and, in general, better classification rates (sensitivities and specificities for external dataset: 67100 %) were obtained compared to those achieved using physicochemical or sensorial data. So, the work carried out is a proof-of-principle that the proposed electrochemical device could be a practical and versatile tool for, in a single and fast electrochemical assay, successfully discriminate olive oils with different storage times and/or exposed to different light conditions.The authors acknowledge the financial support from the strategic funding of UID/BIO/04469/2013 unit, from Project POCI-01-0145-FEDER-006984—Associate Laboratory LSRELCM funded by FEDER funds through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia and under the strategic funding of UID/BIO/04469/2013 unit. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/BD/104038/2014).info:eu-repo/semantics/publishedVersio

Cross-tolerance to abiotic stresses in halophytes: Application for phytoremediation of organic pollutants

International audienceHalopytes are plants able to tolerate high salt concentrations but no clear definition was retained for them. In literature, there are more studies that showed salt-enhanced tolerance to other abiotic stresses compared to investigations that found enhanced salt tolerance by other abiotic stresses in halophytes. The phenomenon by which a plant resistance to a stress induces resistance to another is referred to as cross-tolerance. In this work, we reviewed cross-tolerance in halophytes at the physiological, biochemical, and molecular levels. A special attention was accorded to the cross-tolerance between salinity and organic pollutants that could allow halophytes a higher potential of xenobiotic phytoremediation in comparison with glycophytes

Application of an electronic tongue for Tunisian olive oils' classification according to olive cultivar or physicochemical parameters

Olive oil commercialization has a great impact on the economy of several countries, namely Tunisia, being prone to frauds. Therefore, it is important to establish analytical techniques to ensure labeling correctness concerning olive oil quality and olive cultivar. Traditional analytical techniques are quite expensive, time consuming and hardly applied in situ, considering the harsh environments of the olive industry. In this work, the feasibility of applying a potentiometric electronic tongue with cross-sensitivity lipid membranes to discriminate Tunisian olive oils according to their quality level (i.e., extra virgin, virgin or lampante olive oils) or autochthonous olive cultivar (i.e., cv Chétoui and cv Shali) was evaluated for the first time. Linear discrimination analysis coupled with the simulated annealing variable selection algorithm showed that the signal profiles of olive oils hydroethanolic extracts allowed olive oils discrimination according to physicochemical quality level (classification model based on 25 signals enabling 84 ± 9% correct classifications for repeated K-fold cross-validation), and olive cultivar (classification model based on 20 signals with an average sensitivity of 94 ± 6% for repeated K-fold cross-validation), regardless of the geographical origin and olive variety or the olive quality, respectively. The results confirmed, for the first time, the potential discrimination of the electronic tongue, attributed to the observed quantitative response (sensitivities ranging from 66.6 to +57.7 mV/decade) of the E-tongue multi-sensors towards standard solutions of polar compounds (aldehydes, esters and alcohols) usually found in olive oils and that are related to their sensory positive attributes like green and fruity.This work was financially supported by Project POCI-01–0145-FEDER-006984–Associate Laboratory LSRE-LCM and by Project UID/QUI/00616/2013–CQ-VR both funded by FEDER—Fundo Europeu de Desenvolvimento Regional through COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCTFundação para a Ciência e a Tecnologia, Portugal. Strategic funding of UID/BIO/04469/2013 unit is also acknowledged. Nuno Rodrigues thanks FCT, POPH-QREN and FSE for the Ph.D. Grant (SFRH/ BD/104038/2014).info:eu-repo/semantics/publishedVersio

New [4]helicene derivatives Synthesis, characterization and photophysical properties

International audienceThe design and synthesis of new [4]helicene derivatives were carried out by incorporating well-defined electron donor and acceptor groups at selected positions of the aromatic nuclei, aiming to use them in optical applications. Helicenes have been obtained in good overall yields through a five-step sequence involving mild experimental conditions and easy purification. Photophysical properties of these tetracyclic systems have been evaluated by UV–visible absorption and fluorescence spectroscopies and an emission in the visible region was observed

Modeling bubble flow in fracture with lattice Boltzmann model

International audienceIn the framework of radioactive waste disposal studies, behaviorof hydrogen produced through anaerobic corrosion of the steel canisters is akey point. At the near and far field scale, the migration process of hydrogenis modeled using macroscopic two-phase flow models requiring macroscopicdata like relative permeability curves. As relative permeability curves for verylow permeable media are difficult to measure experimentally, two-phase flowmodelling at the pore scale appears as an interesting tool. The objective of thispaper is to present a Lattice Boltzmann approach used to model two-phaseflow in fractures with apertures of a few micrometers in aperture and someelementary simulations of bubble flow allowing to understand the behavior oftwo-phase flow in very low gas saturation contex

Lattice Boltzmann Model for bubble flow simulation in thin rock fractures

International audienceIn the context of radioactive waste disposal in deep geological formations, the anaerobic corrosion of steel canisters is expected to produce hydrogen. The produced hydrogen behavior is then of interest because of its potential impacts on the radionuclides migration in the geological media. Thus, the major concern is the pressure build-up of trapped hydrogen inside disposal vault and consequently the potential fracking of the geological host-rock with an increase of the excavated damaged zone extension and of the rock permeability. A possible pathway for hydrogen to escape the repository vault is to flow through thin water saturated fractures of tens of micros in thickness. Assuming that hydrogen bubble flow can occur in those fractures, our objective is to study the behavior of the hydrogen bubbles by mean of numerical modeling. On one hand, X-ray micro tomography allows today to precisely picture the rock fractures of interest and one the other hand, a large set of numerical tools can allow to model two-phase flow with interface description. We choose to use a Lattice Boltzmann approach for two main reasons: the first one lies in the simplicity of program writing with a sequential node description that allows full parallelism approach and the second one in the direct use of tomographic images without any meshing work to perform. Among the large Lattice Boltzmann Methods zoology, we selected the color gradient model and mixed it with a Two Relaxation Time collision operator. The model was implemented using CUDA in order to run on different GPU units from laptop GPU to GPU clusters. Basic validation tests such as verification of Laplace law for a bubble in water or multiphase layered Poiseuille flow velocity profiles were successfully conducted. Numerical simulation of bubble flow in real fracture geometries presenting a variable aperture exhibits a bubble trapping process which was not initially expected. In order to focus on this process some simulations were conducted on simplest academic geometries similar to the ones used in micro-fluidic problems where bubbles face smallest apertures during their displacement . The results obtained are presented and discussed

Effects of barium deficiency on structural, magnetic and magnetocaloric properties of La 0.6

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