Literatura científica selecionada sobre o tema "Microparticules d’oxydes de fer"
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Artigos de revistas sobre o assunto "Microparticules d’oxydes de fer"
Matos, Alex Costa, Franciolli da Silva Dantas Araújo, Amanda Alves Fecury, Euzébio Oliveira, Carla Viana Dendasck e Claudio Alberto Gellis de Mattos Dias. "Vue d’ensemble nationale du zinc entre 2010 et 2014". Revista Científica Multidisciplinar Núcleo do Conhecimento, 25 de setembro de 2018, 05–11. http://dx.doi.org/10.32749/nucleodoconhecimento.com.br/biologie/vue-densemble-nationale.
Texto completo da fonteTeses / dissertações sobre o assunto "Microparticules d’oxydes de fer"
Picot, Audrey. "Develοpment οf a theranοstic agent fοr micrοthrοmbοsis during ischemic strοke". Electronic Thesis or Diss., Normandie, 2024. http://www.theses.fr/2024NORMC418.
Texto completo da fonteThere is emerging evidence suggesting that ischemic stroke is frequently associated with the formation of microthrombi in downstream microcirculation. These microthrombi are associated with increased lesion size, cognitive decline, and dementia. Unfortunately, these microthrombi are difficult to detect with current imaging methods. To address this, a novel theranostic agent was developed, IO@PDA@tPA, combining iron oxide microparticles (IO) coated with polydopamine (PDA) and conjugated with recombinant tissue-type plasminogen activator (r-tPA). This agent exhibits in vitro clot lysis activity and reduces reactive oxygen species in neurons under oxygen-glucose deprivation. In vivo, administration of IO@PDA@tPA at one-quarter of the standard r-tPA dose enabled microthrombi visualization and degradation as detected by T2*-weighted magnetic resonance imaging (MRI). This treatment significantly reduced lesion size and promoted recanalization 24 hours after stroke onset. In a hyperglycemic mouse model of IS, the agent showed similar efficacy compared to r-tPA without increasing hemorrhagic risk, a common complication of free r-tPA. Additionally, full functional recovery was observed within five days post-stroke. Thus, IO@PDA@tPA represents a promising theranostic tool for targeting cerebral microthrombi, reducing the required r-tPA dose and associated side effects
Laine, Fabien. "Synthèses, caractérisations structurales et propriétés physiques d’oxydes de fer". Caen, 2016. http://www.theses.fr/2016CAEN2018.
Texto completo da fonteThis thesis work remains part of a context of research on multiferroic materials which present charge order and concerns the synthesis and physicochemical characterization of iron borates. Among these compounds, the ludwigite Fe2+2Fe3+O2BO3 has sparked particular interest due to its interesting electronic and magnetic properties. Indeed, this oxyborate exhibits a structural transition at TCO = 283 K, and two magnetic transitions are observed, at 112 K and 75 K. We have examined the influence of the cationic substitution in the Fe3-xMnxO2BO3 solid solution (0
Daou, Toufic Jean. "Synthèse et fonctionnalisation de nanoparticules d’oxydes de fer magnétiques". Université Louis Pasteur (Strasbourg) (1971-2008), 2007. https://publication-theses.unistra.fr/public/theses_doctorat/2007/DAOU_Toufic_Jean_2007.pdf.
Texto completo da fonteIn the first part, magnetite nanoparticles with controlled size have been synthesized by co-precipitation followed by hydrothermal treatment. By varying different parameters like the pH, the nature of the bases and the Base/Fe ratio, we were able to obtain, nanoparticles with an average size of 12 (± 2) nm but especially of 39 (± 5) nm with global composition: Fe2. 95O4 which can be described by a core-shell system with stoechiometric magnetite as core and oxidized layer as shell. In the second part, we report, our results on the direct and strong bonding of functional organic molecules onto the surface of this nanoparticles using either phosphate, phosphonate or carboxylate groups as coupling agents. These studies have shown that the nanoparticles functionalised by a phosphate or phosphonate groups allowed stronger bonding on the surface of the nanoparticles, higher grafting rate than the carboxylate groups and especially the conservation of the magnetic properties. The grafting occurs mainly by interaction with the Fe3+ in octahedral sites present in the (111) denser plane. The magnetic properties are not modified with phosphonate and phosphate, whereas the carboxylate induce a canting of spin in the oxidized layer decreasing magnetization. Optimisation of grafting conditions has conducted to very stable suspensions in water and THF
Duchateau, Anne. "Réduction par électrolyse de nanoparticules d’oxydes de fer en milieu alcalin à 110°C". Paris 6, 2013. http://www.theses.fr/2013PA066533.
Texto completo da fonteIron oxides play an important role in steel industry as precursors of iron. The current iron production process in blast furnaces is responsible for 3 to 5% of the world CO2 rejections. Reducing the iron oxides in suspension by electrolysis in strongly alkaline medium (18 M) at 110°C is a promising way to lower the CO2 rejections while improving steel production efficiency, that has been studied for years. The aim of this work is the determination of the most reliable oxide concerning metallic iron production and a more accurate comprehension of the electrolytic reduction mechanisms in order optimize the production process. The experiments are carried out on iron oxides nanoparticles (hematite, goethite, lepidocrocite, akaganeite, magnetite) synthesized according to well known methods which allow us to obtain perfectly defined objects concerning the structure, size and morphology. Hematite is the only oxide to be stable in the 18 M sodium hydroxide solution for a long lasting period. The ageing of the other iron oxides nanoparticles in hot concentrated sodium hydroxide solution led to the formation of sodium ferrite NaFeO2, the transformation duration depending on the starting iron oxide. NaFeO2 precipitation competes with the reduction reaction and lead to less reproducibility and/or less good performances. Indeed, the dissolved ferric species are the intermediates of the reduction by electrolysis mechanism and ions consumption by NaFeO2 precipitation is obviously harmful to metallic iron production. The most reliable oxides are commercial Hematite particles because of the good yields and the important metallic iron weights obtained with reproducibility
Delacotte, Charlène. "Etudes structurales d’oxydes et d’oxysulfures dans le système calcium/fer en corrélation avec leurs propriétés physiques". Caen, 2015. http://www.theses.fr/2015CAEN2037.
Texto completo da fonteThis report deals with the correlations existing between the structure and the physical properties of mixed valence state iron oxides with the formula CaFe2+nO4+n, and new oxysulfides compounds belonging to the Ca-Fe-O-S system. This exploratory work allowed to isolate four phases (powder and single crystals): CaFe5O7 (n=3), CaFe3O5 (n=1), CaOFeS and CaO1. 5Fe1. 25S. Crystalline structures were characterized, as function of temperature, by X-rays diffraction and transmission electron microscopy. The Mössbauer spectroscopy allowed to reach the oxidation degrees and the local environment of iron atoms according to the temperature and neutron diffraction allowed to define magnetic structures. During this thesis work, the use of complementary characterization techniques was essential due to the complexity of the observed transitions. Physical properties of materials were characterized by electrical resistivity, magnetic susceptibility, Seebeck coefficient or dielectric measurements
Rizki, Youssef. "Structure et propriétés physiques d’oxydes de fer à valence mixte SrFe1-x(Sc,Sn)xO3-d". Rouen, 2011. http://www.theses.fr/2011ROUES048.
Texto completo da fonteIn this thesis, the relationship between structure and physical properties of new transition-metal oxides of the SrFe1-x(Sc,Sn)xO3-d (M = Sc, Sn) type has been investigated. The structural characterization was performed by X-ray diffraction and transmission electron microscopy. Mössbauer spectrometry has been used to investigate both the oxidation state of iron and its local environment. The physical properties of the compounds were characterized by resistivity measurements with and without applied magnetic field, magnetic susceptibility measurements, magnetization measurements as a function of magnetic field or temperature. The substitution of iron by a nonmagnetic trivalent ion such as Sc3+ leads to a decrease in the oxygen content without affecting the crystalline structure of the compound. However, the substitution is limited and the SrFe0,5Sc0,5O2,5 limit compound can also be chemically synthesized in a brownmillerite ordered structure. Although transport and magnetic properties are strongly affected by such substitution, magnetoresistivity is not significantly altered. The substitution of iron by a tetravalent ion such as Sn4+ cannot maintain constant oxygen content, which increases with the substitution rate. Substitution is not limited, and a structural change is observed for a substitution rate higher than 0. 5. All the physical properties investigated (transport, magnetism, magnetoresistivity) are significantly influenced by the substitution
Tabaja, Nabil. "Nanoparticules d’oxydes de fer et de ferrites obtenues par nano-réplication : réactivité chimique et application en dépollution des eaux". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066315/document.
Texto completo da fonteThis thesis was carried out as part of a Franco-Lebanese collaboration thesis (3 years) between the University of Pierre et Marie Curie in Paris and the Lebanese University in Beirut. Nabil Tabaja was fully funded by the Research Group MAPE (nanosized Porous Materials, Preparation, Advanced Characterization and Environmental Applications) Beirut that we thank.The purpose of this study was to test and develop catalysts based on iron oxides and ferrites for decontamination of water by photocatalysis under visible and sunlight. The catalysts studied were prepared by using porous silica as templates to obtain predominantly either nanoparticles, NP, iron oxides having crystallized within the pores of the silica (INTERNAL, replicated), or nanoparticles having crystallized outside the silica grains formed and during the thermal activation treatments (external). We employed techniques easily transferable to obtain silicas (Chapter 1). Our goal at this level was more than 50 grams of at least six silicas having different diameters of mesopores. The change in these diameters is accompanied by changes in connections between major mesoporous silicas and the properties of surfaces. Various iron precursor salts (chloride or nitrate) or metal mixtures were deposited on the various silicas obtained by the two solvents techniques (2S). The samples were calcined at 700 ° C in air to obtain oxide nanoparticles (Chapter 2). We show that, if the diameter of NP nanoreplicated is generally close to the pore diameter of the initial silicas, and forms the dispersion of nanoparticles in the inner silica grain depends on various experimental factors of the precursor salts, solvents and the type of the selected silica. We also show that the formation of particles is associated with the external heat treatment can be promoted and imposed by choosing the right solvent and the right precursor salt for a specific silica. Initial tests have demonstrated an important release rate in the case of iron catalyst, we tested different compositions ferrites ((II) cations of different electronegativities, Ni (II), Co (II), Cd (II), Zn (II) cation (III), Cr (III)). In order to compare the catalytic activity of the catalysts, two types of reactions are successively introduced. The first type of reaction, the photocatalytic oxidation of methanol and formaldehyde was employed as fundamental. In this case, our objective was to study the selectivity of the reaction and identify what way inambigue nanoparticles in the formulation of catalysts allow, starting from a species to a single carbon, to obtain products with 2 or more carbon atoms (Chapter III). The second reaction, the photocatalytic oxidation of a pesticide, was used to demonstrate that the catalysts may be useful as applied. The pesticide was selected carbendazim (Chapter IV) which we have followed the breakdown. These studies have been possible thanks to the use of advanced characterization techniques, type TOC and GC-MS. The best catalytic activities were analyzed according to the presence of a majority of internal and / or external NP and other species more dispersed and invisible by XRD
Tabaja, Nabil. "Nanoparticules d’oxydes de fer et de ferrites obtenues par nano-réplication : réactivité chimique et application en dépollution des eaux". Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066315.
Texto completo da fonteThis thesis was carried out as part of a Franco-Lebanese collaboration thesis (3 years) between the University of Pierre et Marie Curie in Paris and the Lebanese University in Beirut. Nabil Tabaja was fully funded by the Research Group MAPE (nanosized Porous Materials, Preparation, Advanced Characterization and Environmental Applications) Beirut that we thank.The purpose of this study was to test and develop catalysts based on iron oxides and ferrites for decontamination of water by photocatalysis under visible and sunlight. The catalysts studied were prepared by using porous silica as templates to obtain predominantly either nanoparticles, NP, iron oxides having crystallized within the pores of the silica (INTERNAL, replicated), or nanoparticles having crystallized outside the silica grains formed and during the thermal activation treatments (external). We employed techniques easily transferable to obtain silicas (Chapter 1). Our goal at this level was more than 50 grams of at least six silicas having different diameters of mesopores. The change in these diameters is accompanied by changes in connections between major mesoporous silicas and the properties of surfaces. Various iron precursor salts (chloride or nitrate) or metal mixtures were deposited on the various silicas obtained by the two solvents techniques (2S). The samples were calcined at 700 ° C in air to obtain oxide nanoparticles (Chapter 2). We show that, if the diameter of NP nanoreplicated is generally close to the pore diameter of the initial silicas, and forms the dispersion of nanoparticles in the inner silica grain depends on various experimental factors of the precursor salts, solvents and the type of the selected silica. We also show that the formation of particles is associated with the external heat treatment can be promoted and imposed by choosing the right solvent and the right precursor salt for a specific silica. Initial tests have demonstrated an important release rate in the case of iron catalyst, we tested different compositions ferrites ((II) cations of different electronegativities, Ni (II), Co (II), Cd (II), Zn (II) cation (III), Cr (III)). In order to compare the catalytic activity of the catalysts, two types of reactions are successively introduced. The first type of reaction, the photocatalytic oxidation of methanol and formaldehyde was employed as fundamental. In this case, our objective was to study the selectivity of the reaction and identify what way inambigue nanoparticles in the formulation of catalysts allow, starting from a species to a single carbon, to obtain products with 2 or more carbon atoms (Chapter III). The second reaction, the photocatalytic oxidation of a pesticide, was used to demonstrate that the catalysts may be useful as applied. The pesticide was selected carbendazim (Chapter IV) which we have followed the breakdown. These studies have been possible thanks to the use of advanced characterization techniques, type TOC and GC-MS. The best catalytic activities were analyzed according to the presence of a majority of internal and / or external NP and other species more dispersed and invisible by XRD
Rodrigues, Romain. "Mécanisme et cinétique de la déchloration réductrice de l'hexachlorobutadiène et de l'hexachloroéthane par action de réactifs à base de fer zéro-valent". Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30294/document.
Texto completo da fonteThis work focused on the reductive dechlorination of hexachlorobutadiene (HCBD) and hexachloroethane (HCA). The first part consisted of experimental measurement of solubility data for both compounds (i) at different temperatures and (ii) in the presence of surfactants. Thermodynamic parameters for dissolution have been calculated in order to propose a physical explacation of the minimum solubility observed between 12 and 45 °C. The second part, based on a preliminary selection of a reaction for its efficiency, aimed to investigate the mechanism of the reductive dechlorination of HCBD and HCA by Pd/Fe microparticles in suspension in polylactic acid. Different experimental conditions have shown that atomic hydrogen is the main reductant of the system. Different kinetic laws were then used for the modeling of the disappearance of HCBD and HCA, taken separately and in mixture
Gautier, Juliette. "Nanoparticules d'oxydes de fer PEGylées pour la délivrance de la doxorubicine : développement et évaluation de leur potentiel théragnostique". Thesis, Tours, 2013. http://www.theses.fr/2013TOUR3805/document.
Texto completo da fontePEGylated superparamagnetic iron oxide nanoparticles (SPIONs) were used as a platform to build theranostic nanovectors for the delivery of an anticancer drug, doxorubicin (DOX). The DOX loading on nanocarriers via a DOX-iron (II) complex was optimized. The complex dissociates at low pH, typical of intracellular compartments. Surface enhanced Raman scattering (SERS) confirmed that the nanovectors released DOX under free form. In vitro cytotoxicity due to DOX loaded on nanocarriers was performed on different breast cancer cells, and compared to that of DOX in solution. Internalization pathways of nanovectors were explored with transmission electron microscopy (TEM), and intracellular fate of DOX was monitored by confocal spectral imaging (CSI). To finish, a therapeutical protocol was performed on tumorized mice, in order to evaluate the efficacy of the nanoformulation on tumor reduction, the possibility of magnetic targeting, and the decrease of side effects induced by DOX