The study of self-sensing cementitious materials is a constantly expanding topic of study in the materials and civil engineering fields and refers to the creation and utilization of cement-based materials (including cement paste, cement mortar, and concrete) that are capable of sensing (i.e. measuring) stress and strain states without the use of embedded or attached sensors. With the inclusion of electrically conductive fillers, cementitious materials can become truly self-sensing. Previous researchers have provided only qualitative studies of self-sensing material stress-electrical response. The overall goal of this research was to modify and apply previously developed predictive models on cylinder compression test data in order to provide a means to quantify stress-strain behavior from electrical response. The Vipulanandan and Mohammed (2015) stress-resistivity model was selected and modified to predict the stress state, up to yield, of cement cylinders enhanced with nanoscale iron(III) oxide (nanoFe2O3) particles based on three mix design parameters: nanoFe2O3 content, water-cement ratio, and curing time. With the addition of a nonlinear model, parameter values were obtained and compiled for each combination of nanoFe2O3 content and water-cement ratio for the 28-day cured cylinders. This research provides a procedure and lays the framework for future expansion of the predictive model.

Dans le cadre de ce travail de thèse, la polymérisation de type RAFT a été exploitée pour synthétiser des particules de latex magnétiques décorées de polymères stimulables. Cinq (co)polymères hydrophiles ont tout d'abord été préparés via la (co)polymérisation RAFT en solution d'acide acrylique (AA) et de méthacrylate de 2-diméthylaminoéthyle (MADAME). Les agents macromoléculaires obtenus (macroRAFT) : des homopolymères de PAA ou PMADAME ainsi que des copolymères P(AA-co-MADAME), présentent une sensibilité au pH et à la température. Ces macroRAFT hydrophiles ont ensuite été utilisés dans des réactions d’extension de chaîne avec du styrène conduisant à la formation de copolymères à blocs amphiphiles bien définis. Puis, des dispersions aqueuses d’agrégats (clusters) de nanoparticules d’oxyde de fer (OF) ont ensuite été préparées via un procédé de mini-émulsification/évaporation de solvant, en utilisant les copolymères à blocs comme stabilisants. Après optimisation des conditions expérimentales (sonication, concentration de macroRAFT, pH), des agrégats de taille contrôlée (45 à 300 nm) ont pu être obtenus. Ces clusters ont ensuite été utilisés comme semence lors de la polymérisation en émulsion du styrène, conduite en présence d’un agent de réticulation. Les clusters d'OF ont été individuellement encapsulés par une couche de polymère, formant des particules magnétiques stabilisées par le segment hydrophile des copolymères à blocs. Enfin, les particules magnétiques décorées de copolymères de P(AA-co-MADAME) ont été utilisées avec succès pour la capture et le relargage de bactéries grâce à la modulation de leurs propriétés de surface en fonction du pH / In this work reversible addition-fragmentation chain transfer (RAFT) polymerization was exploited to synthesize magnetic latex particles decorated with stimuli-responsive polymer brushes. First, five hydrophilic (co)polymers with various compositions were successfully prepared by RAFT solution (co)polymerization of acrylic acid (AA) and 2-dimethylaminoethyl methacrylate (DMAEMA) for different AA to DMAEMA molar ratios. The obtained macromolecular RAFT agents (macroRAFTs), PAA or PDMAEMA homopolymers and P(AA-co-DMAEMA) copolymers, displayed interesting pH- and thermo-responsive properties. These hydrophilic macroRAFTs were then chain extended with styrene leading to the formation of well-defined amphiphilic block copolymers. An aqueous dispersion of iron oxide clusters was next prepared using a strategy based on emulsification/solvent evaporation in which the block copolymers were used as stabilizers. By varying the experimental conditions (sonication power, macroRAFT concentration and pH of the medium), the cluster size could be controlled from 45 up to 300 nm. These clusters were then used as seeds in styrene emulsion polymerization in the presence of a crosslinker. The iron oxide clusters were individually encapsulated into a polymer shell generating latex particles, stabilized by the hydrophilic segment of the block copolymers, and displaying interesting magnetic properties. At last, these magnetic beads were evaluated as carriers in the magnetic separation of bacteria. The magnetic latex particles decorated with P(AA-co-DMAEMA) copolymers were successfully employed for the capture and trigger release of bacteria, allowing their concentration in a biological sample

Preparation and performance of the perovskite-type barium strontium cobalt iron oxide (Ba_0.5 Sr_0.5 Co_0.8 Fe_0.2 O_(3-δ), BSCF) and its doped compositions were studied in this dissertation. Three transition metals (copper, nickel and niobium) were substituted into the parent BSCF at various ratios to create the formula Ba_0.5 Sr_0.5 (Co_0.8 Fe_0.2)_(1-x) M_x O_(3-δ) (0.02≤x≤0.30; M=Cu,Ni or Nb). Two synthetic methods (solid-state reaction and wet chemical co-precipitation) were developed for the preparation of starting powders. In the previous reports [1, 2], BSCF ceramics suffered from insufficient densification and severe cracking; these problems were resolved in this study by optimising the ceramic processing conditions. The phase transition sequences from starting powders to single-phase cubic perovskite were studied by SEM, XRD, TGA, EDS and Raman spectroscopy. The powders prepared by solid-state method were found to require higher calcination temperature to form pure perovskite phase, and an extra intermediate structure (Ba,Sr)Fe_2 O_4 was detected in the reaction sequence. The materials performance was examined from five aspects: thermal stability, chemical stability, oxygen permeability, electronic conductivity and mechanical performance. The secondary phases of thermal/chemical degradation were investigated, and a needle-like intragranular precipitate was originally discovered in this work. It was discovered that the niobium substitution could significantly improve BSCF’s thermal stability and chemical stability. The oxygen permeability and mechanical performance were also improved by niobium when the substitution ratios are small (< 10%). Although the electronic conductivity was lowered by niobium substitution as a trade-off, it does not become a drawback to restrict the materials’ potential applications as mixed ionic-electronic conductors (MIEC).Furthermore, the material system’s “composition - lattice structure - performance” relationships were systematically investigated in this work; the oxygen deficiency value (δ) and the average bond energy (ABE) were found to have strong correlations with the materials performance.

Ce travail de thèse décrit l'élaboration de latex hybrides oxyde de fer (OF)/polymère par polymérisation en émulsion sans tensioactif. Des nanoparticules d'OF cationiques ont été tout d'abord synthétisées par co-précipitation de sels de fer dans l'eau. Des latex hybrides magnétiques ont été ensuite obtenus par deux voies de polymérisation. La première consiste en la synthèse de particules de latex de morphologie 'carapace' par polymérisation en émulsion Pickering du styrène et du méthacrylate de méthyle (MMA). Un comonomère auxiliaire (acide (méth)acrylique ou acide 2-acrylamido-2-méthyl-1-propane sulfonique) a été utilisé pour favoriser l'adsorption des OF à la surface des particules de polymère produites. Les analyses par MET indiquent la présence d'OF à la surface des particules de polymère (structure carapace). L'analyse thermogravimétrique a permis de quantifier l'efficacité d'incorporation des OF, i.e. la fraction d'OF initialement introduits effectivement adsorbés à la surface des particules. L'efficacité d'incorporation augmente avec la quantité de comonomère auxiliaire, le pH et la concentration en OF et dépend de la nature du monomère hydrophobe. Dans la deuxième voie, les OF ont été encapsulés par polymérisation radicalaire contrôlée par transfert de chaîne réversible par addition-fragmentation (RAFT) en émulsion aqueuse. La stratégie utilisée repose sur l'utilisation de macroagents RAFT amphiphiles comportant des groupements acide carboxylique connus pour interagir avec la surface des OF. L'interaction entre les macroRAFTs et les OF a été étudiée à travers le tracé de l'isotherme d'adsorption. Des analyses SAXS et DLS indiquent la formation de clusters d'oxyde de fer. Ces derniers ont été ensuite engagés dans la polymérisation en émulsion du styrène ou d'un mélange de MMA et d'ABu (ratio massique : 90/10) pour former une écorce de polymère à leur surface. Les particules carapace et les OF encapsulés affichent un comportement superparamagnétique / This work describes the elaboration of polymer/iron oxide (IO) hybrid latexes through surfactant-free emulsion polymerization. Cationic iron oxide nanoparticles stabilized by nitrate counterions were first synthesized by the co-precipitation of iron salts in water. Magnetic hybrid latexes were next obtained by two polymerization routes carried out in the presence of IO. The first route consists in the synthesis of polymer latexes armored with IO via Pickering emulsion polymerization of methyl methacrylate (MMA) or styrene (St). An auxiliary comonomer (namely methacrylic acid, acrylic acid or 2-acrylamido-2-methy-1- propane sulfonic acid) was used to promote IO particle adhesion to the surface of the generated polymer particles. TEM showed the presence of IO at the surface of the polymer particles and the successful formation of IO-armored polymer particles. TGA was used to quantify the IO incorporation efficiency, which corresponds to the fraction of IO effectively located at the particle surface. The incorporation efficiency increased with increasing the amount of auxiliary comonomer, suspension pH and IO content or with increasing monomer hydrophobicity. In the second route, IO encapsulation was investigated via reversible addition-fragmentation chain transfer (RAFT)-mediated emulsion polymerization. The developed strategy relies on the use of water-soluble amphipathic macromolecular RAFT agents containing carboxylic acid groups, designed to interact with IO surface. The interaction between the macroRAFT agents and IO was investigated by the study of the adsorption isotherms. Both DLS and SAXS measurements indicated the formation of dense IO clusters. These clusters were then engaged in the emulsion polymerization of St or of MMA and nbutyl acrylate (90/10 wt/wt) to form a polymer shell at their surface. Both IO-armored latex particles and polymer-encapsulated clusters display a superparamagnetic behavior

The optical response of several magnetic nanoparticle dispersions is studied by angle resolved transmittance at wavelength of 600 nm in zero-field and under an applied magnetic field of 0.1 T, with the purpose of exploring to what extent this could be used as a method of monitoring the colloidal dispersions. In an external magnetic field, magnetic particles will start to order into needle-like structures aligned with the field, which was observed by microscopy. This will change the light scattering caused by the particles. Results showed a clear effect from applying the magnetic field by a dip in the transmitted intensity at angles around 3-5 degrees. The scattering is compared to that of a homogeneous infinite cylinder and theoretical explanations to the effect are discussed. Spectrophotometry at wavelengths between 300-1100 nm is performed and compared with calculations from Kubelka-Munk approximation to give a first characterization of the particle dispersions. Particles used in this project are magnetite, Fe3O4, and maghemite, gamma-Fe2O3, nanoparticles with sizes ranging from 5-250 nm.

The Bergslagen ore province, located in the Fennoscandian shield in the south-central part of Sweden hosts several metallic mineral deposits, one of them being the Källfallsgruvan iron-oxide deposit in the Riddarhyttan ore field, situated in a high-strain shear belt denoted as the West Bergslagen Boundary Zone (WBBZ).  An accurate 3D geological model of the Källfallsgruvan iron-oxide deposit has been generated to aid understanding of the ore body geometries and calculating volume and tonnage. The methodology of this study consisted of assessing existing data in the form of legacy mine maps and to integrate new data from field work, drill core logging and 3D geological modelling. The work has resulted in structural interpretations that are put in the context of the regional structural framework in Bergslagen consisting of three deformation events (D1, D2 and D3) and two metamorphic events (M1 and M2). The field work resulted in six rock units being defined used to construct a geological map, in addition the structural measurements resulted in a hypothetical semi-regional fold and evidence of ductile strike-slip/dip-slip shearing. Logging of drill cores resulted in three rock units being defined, two of them related to the mineralization and one characterizing the host rock (± local variations), correlating to the observed host rock from the field work. The rock units discovered from both the field work and drill core logging are all interpreted to be the metamorphic products of volcanic rocks subjected to alteration of varying degree. Based upon geological field observations with subsurface data and 3D geological modelling it is concluded that, 1) The deposit comprises multiple ore bodies that jointly resemble an S-shaped synform that is steeply inclined-upright, moderately-steeply plunging towards the southwest with an axial plane striking northeast-southwest. The deposit is interpreted to be geometrically controlled by an F2 fold, possibly displaying an interference pattern of type 1, favouring progressive shearing and deformation solely related to D2, 2) Evidence of at least one generation of transpressional tectonic regime exists, interpreted to be D2, 3) The estimated tonnage of 4 938 610 tons of the massive magnetite and semi-massive mineralization revealed that a deposit of such tonnage is presently not economically viable. However, if the Källfallsgruvan iron-oxide deposit or similar is determined to have a significant REE content, such deposit may then be of economic interest and, 4) Possible mineral exploration indicators around Källfalls-like deposits are intensely altered rocks related to magnesium alteration, consisting dominantly of quartz, biotite (increasing towards mineralization), muscovite, chlorite, anthophyllite and cordierite, affected by parasitic folding. / Bergslagen malmprovins, belägen i den Fennoskandiska skölden i sydcentrala delen av Sverige innehåller flera metall mineralfyndigheter, varav en av dem är Källfallsgruvan järnoxidfyndighet i Riddarhyttan malmfält, belägen i en skjuvzon kallat för ”West Bergslagen Boundary Zone (WBBZ)”. En representativ 3D geologisk model av Källfallsgruvan järnoxidfyndighet har genererats för att öka förståelsen av malmkroppens geometrier samt beräkna volym och tonnage. Metodiken bestod av att bedöma existerande data så som gruvkartor och integrera nya data genom fältarbete, borrkärnekartering och 3D geologisk modellering. Arbetet resulterade i strukturella tolkningar som sattes i kontexten av den regionala strukturella bilden i Bergslagen bestående av tre deformations event (D1, D2 och D3) och två metamorfa event (M1 och M2). Fältarbetet resulterade i att sex bergartsenheter definierades som användes för att konstruera en geologisk karta samt så har de strukturella mätningarna resulterat i ett hypotetiskt semi-regionalt veck och bevis för duktil strike-slip-/normal-skjuvning. Borrkärnekarteringen resulterade i att tre bergartsenheter definierades, varav två var relaterade till mineraliseringen och en kännetecknade värdbergarten (± lokala variationer) som korrelerar med den observerade värdbergarten från fältarbetet. Bergartsenheterna som upptäcktes från både fältarbetet och borrkärnekarteringen har tolkats vara metamorfa produkter av vulkaniska bergarter som omvandlats i varierande grad. Baserat på de geologiska fältobservationerna med underjordsdata och 3D geologisk modellering dras följande slutsatser, 1) Fyndigheten består av multipla malmkroppar som gemensamt liknar en S-formad synform som är brant lutande-upprätt, måttligt-brant stupande mot sydväst med ett axialplan som stryker nordost-sydväst. Fyndigheten tolkas vara geometriskt kontrollerat av ett F2 veck, som möjligtvis påvisar ett interferensmönster av typ 1 bildat genom progressiv skjuvning och deformation endast relaterat till D2, 2) Bevis för minst en generation av transpressionstektonisk miljö existerar vilket tolkats vara D2, 3) Det estimerade tonnaget på 4 938 610 ton för den massiva magnetit och semi-massiva mineraliseringen visade att en fyndighet av sådant tonnage är för nuvarande inte ekonomiskt hållbart. Om Källfallsgruvan järnoxidfyndighet eller liknande fyndighet bestäms att ha ett betydande REE innehåll så skulle en sådan fyndighet vara av ekonomiskt intresse och, 4) Möjliga prospekteringsindikatorer runt Källfalls-liknande fyndigheter är intensivt omvandlade bergarter relaterad till magnesiumomvandling främst bestående av kvarts, biotit (ökar mot mineraliseringen), muskovit, klorit, antofyllit och kordierit, påverkad av parasitisk veckning.

No description available.

Ces travaux de thèse s'inscrivent dans le contexte de l'imagerie moléculaire, qui vise à adapter les traitements de pathologies à la variabilité de chaque patient, grâce à l'imagerie de biomarqueurs cellulaires ou moléculaires. En particulier, l'imagerie par résonance magnétique (IRM) couplée a des nanoparticules d’oxyde de fer innovantes pourrait permettre de relever un tel défi.Cette thèse se concentre sur l'étude d'une nouvelle classe d'agents de contraste à base d'oxyde de fer pour l'IRM à haut champ magnétique. En effet, les magnétosomes sont des vésicules d’oxyde de fer produites naturellement par des bactéries appelées bactéries magnétotactiques. De telles bactéries synthétisent ces vésicules magnétiques et les alignent comme l'aiguille d'une boussole, ce qui facilite leur navigation dans les sédiments. Ces bactéries produisent donc des magnétosomes aux propriétés magnétiques exceptionnelles: 50 nm de diamètre, mono-cristallin, mono-domaine magnétique et avec une haute magnétisation à saturation. De plus, une grande variété de souches bactériennes existent dans la nature, et produisent, avec une grande stabilité, des magnétosomes dont la taille, la forme, et le contenu chimique, sont déterminés génétiquement. Enfin, les magnétosomes sont naturellement porteurs d'une membrane bi-lipidique dont le contenu est également déterminé génétiquement. Récemment, le contenu protéique de la membrane des magnétosomes a été mis à jour, ouvrant la voie à la fonctionnalisation de cette dernière par fusion des gènes codant pour des protéines présentes abondamment à la membrane avec ceux codant pour un peptide d’intérêt.Ainsi, l'utilisation de ces micro-organismes pour produire des agents de contraste innovants et fonctionnalisés pour l'imagerie moléculaire par IRM, et les applications qui en découlent, ont été étudiées pendant cette thèse. La production et l'ingénierie des magnétosomes a été réalisée par nos collègues du Laboratoire de Bioénergétique Cellulaire (LBC, CEA Cadarache), et sera présentée et discutée. Des magnétosomes sauvages ont d'abord été caractérisés en tant qu'agents de contraste pour l'IRM. De tel magnétosomes présentent des propriétés contrastantes très intéressantes pour l'IRM, ce qui a été validé à la fois in vitro puis in vivo. L'étude de faisabilité de la production d'un agent de contraste pour l'imagerie moléculaire par IRM en une seule étape, à l'aide des bactéries magnétotactiques, a été réalisée sur un modèle de souris porteur de glioblastome. Sachant par la littérature que les cellules tumorales sur-expriment les intégrines anb3, et que ces dernières peuvent être ciblées par le peptide RGD, il a été choisi de produire des magnétosomes exprimant le peptide RGD à leur membrane. L'affinité de tels magnétosomes pour les cellules tumorales U87 a été vérifiée in vitro, et démontré in vivo par IRM puis cross-validé par histologie. / This work takes place in the context of molecular imaging, which aims at tailoring medical treatments and therapies to the individual context by revealing molecular or cellular phenomenon of medical interest in the less invasive manner. In particular, it can be acheived with MRI molecular imaging using engineered iron-oxide contrast agent.This PhD thesis focuses on the study of a new class of iron-oxide contrast agent for high field MRI. Indeed, magnetosomes are natural iron-oxide vesicles produced by magnetotactic bacteria. These bacteria synthesized such magnetic vesicles and ordered them like a nano-compass in order to facilitate their navigation in sediments. This explains why magnetosomes are awarded with tremendous magnetic properties: around 50 nm, mono-crystalline, single magnetic domain and high saturation magnetization. Furthermore, a wide variety of bacterial strains exist in nature and size and shape of magnetosomes are highly stable within strain and can be very different between strains. Finally, magnetosomes are naturally coated with a bilipidic membrane whose content is genetically determined. Lately, researchers have unravelled magnetosomes membrane protein contents, opening the way to create functionnalized magnetosomes thanks to fusion of the gene coding for a protein of interest with the gene coding for an abundant protein at magnetosomes membrane.A new alternative path using living organisms to tackle the production of engineered high effciency molecular imaging probes have been investigated with magnetotactic bacteria in this PhD. The production and engineering of magnetosomes have been carried out by our partner, the Laboratoire de Bio-energétique Cellulaire (LBC, CEA Cadarache), and will be presented and discussed. We then characterized magnetosomes as contrast agent for high field MRI. We showed they present very promising contrasting properties in vitro, and assessed this observation in vivo by establishing they can be used as effcient blood pool agent after intravenous injection. Afterward, we applied the concept of producing engineered MRI molecular imaging probes in a single step by bacteria, to a mouse model of glioblastoma. Knowing that tumor cells can be actively targeted through anb3 integrins by RGD, we produced RGD functionnalized magnetosomes. We started from showing these RGD magnetosomes have a good affnity for U87 cell in vitro, prior to demonstrate it in vivo on orthotopic U87 mouse model. This in vivo affnity being fnally cross-validated with histology.

No description available.

Anthrax is severe disease caused by the gram-positive Bacillus anthracis that can affect humans with deadly consequences. The disease propagates via the release of bacterial spores that can be naturally found in animals or can be weaponized and intentionally released into the atmosphere in a terrorist attack. Once inhaled, the spores become activated and the anthrax bacterium starts to reproduce and damage healthy macrophages by the release of the anthrax toxin. The anthrax toxin is composed of three virulent factors: (i) anthrax protective antigen (APA), (ii) anthrax lethal factor (ALF), and (iii) anthrax edema factor (AEF) that work in harmony to effectuate the lethality associated with the disease. Out of the two internalized factors, ALF has been identified to play a critical role in cell death. Studies in animals have shown that mice infected with an anthrax strain lacking ALF survive the infection whereas when ALF is present the survivability of the mice is eliminated. Although the current therapy for anthrax is antibiotic treatment, modern medicine faces some critical limitations when combating infections. Antibiotics have proven very efficient in eliminating the bacterial infection but they lack the ability to destroy or inhibit the toxins released by the bacteria. This is a significant problem since ALF can remain active in the body for days after the infection is eliminated with no way of inhibiting its destructive effects. The use of inhibitors of ALF is an attractive method to treat the pathogenesis of anthrax infections. Over the last decade several inhibitors of the enzymatic activity of ALF have been identified. In order to identify inhibitors of ALF a variety of screening approaches such as library screenings, Mass Spectroscopy- based screenings and scaffold-based NMR screening have been used. Results from these iv screening have yielded mainly small molecules that can inhibit ALF in low micromolar to nanomolar concentrations. Yet, although valuable, these results have very little significance with regards to treating ALF in a real-life scenario since pharmaceutical companies are not willing to invest in further developing these inhibitors. Furthermore, the low incidence of inhalation anthrax, the lack of a market for an ALF inhibitor, and the expenses associated with the approval process of the FDA, have hindered the motivation of pharmaceutical companies to pursuit these kind of drugs. Therefore we have screened a small-molecule library of FDA approved drugs and common molecules in order to identify currently approved FDA drugs that can also inhibit ALF (Chapter III). The screening revealed that five molecules: sulindac, fusaric acid, naproxen, ketoprofen and ibuprofen bound to either ALF or APA with sulindac binding both. Additionally, we have developed a nanoparticle-based screening method that assesses molecular interactions by magnetic relaxation changes (Chapter II). Using this assay, we were able to accurately measure the dissociation constants of different interactions between several ligands and macromolecules. Moreover, we have used computational docking studies to predict the binding site of the identified molecules on the ALF or APA (Chapter IV). These studies predicted that two molecules sulindac and fusaric acid could be potential inhibitors of ALF since they bind at the enzymatic pocket. As a result, we tested the inhibitory potential of these molecules as well as that of the metabolic derivatives of sulindac (Chapter V). Results from these studies provided conclusive evidence that fusaric acid and sulindac were both strong inhibitors of ALF. Furthermore, the metabolic derivatives of sulindac, sulindac sulfide and sulindac sulfone v also inhibited ALF. Overall, taking together these results we have discovered the alternate use of a currently used drug for the treatment of ALF pathogenesis.