The launch environment experiences many vibration, shock, and acoustic loads. A great concern is the high random vibration levels that can damage components and spacecraft structures, which can cause a mission failure. An effective method of reducing high frequency energy is using isolators. Overall, the need for vibration isolation has been increasing because there has been an increase in the use of mechanisms in which vibrations are prevalent. In addition, there has not been extensive research on the effects of isolators that are outgassed and cured. Therefore, it is important to investigate and understand the vibrational effects on isolators. It is convenient to outgas and cure isolators for the benefit of some components because that eliminates contamination, but outgassing and bake-out could potentially affect the frequency response of the isolator system in a negative way. It is valuable to investigate how much outgassing and bake-out might affect the performance, if any, of the vibration isolator in order to benefit companies who may need that kind of information. The vibration isolators used for the purpose of this research were twenty E22-02-40 isolators provided by Barry Controls, a Hutchinson Group Company. The E22-02-40 isolators were outgassed and cured (heated at high temperatures) in order to be turned from grade C into grade A level for outgassing. Then the vibrational performance of those isolators were tested and compared to the isolators that were not outgassed and not cured. Vibration tests were run in the flat frequency spectrum and high frequency spectrum. The maximum percent difference occurred in the grade A level isolators, in which the first frequency mode increased by 33.3 % in the z direction from the grade C isolators. A numerical finite element analysis was performed on Abaqus/CAE in order to verify the experimental results. In addition, a swelling test was conducted on the isolators to test their physical characteristics change after they were outgassed and cured.

Цель работы – установление влияния нейтронного облучения на стабильность структуры и фазового состояния ферритно-мартенситной стали ЭП823. Данная работа посвящена анализу влияния нейтронного облучения на фазовые и структурные составляющие стали. Исследования проводились на образцах оболочек твэлов, облученных в составе материаловедческой сборки в реакторе БН-600 при температурах 570, 600, 660 ˚С до повреждающих доз 51,3, 75,1 и 81,1 сна. Определялись методами металлографии и стереометрического анализа характеристики структурных составляющих, вторичных фаз, образовавшихся в процессе облучения, оценивались характеристики радиационной пористости, плотность дислокаций. Исследования были выполнены на сканирующем электронном микроскопе MIRA3 FEG-SEM, оснащенном детекторами вторичных и отраженных электронов и приставкой энергодисперсионного анализа характеристического рентгеновского излучения x-Act 6 фирмы Oxford Instruments. Так же проводились исследования на просвечивающем электронном микроскопе фирмы JEM-2000EX при ускоряющем напряжении 100 кВ в просвечивающем режиме. Количественная обработка изображений для получения размерных характеристик выделений проводилась с использованием программного обеспечения «Цифровая фотолаборатория SIAMS Photolab», а также при помощи программного обеспечения сканирующего электронного микроскопа MIRE3 FEG-SEM. Проведенное исследование стали Х12НМВБФСР в исходном состоянии показало, что ее структура состоит из мартенсита, остаточного феррита, крупных карбидов на основе Nb и по границам ферритных зерен и мартенситных реек, образуются карбиды типа М23С6. После нейтронного облучения содержание карбидов типа М23С6 увеличивается, в зернах феррита образуется χ-фаза, у которой с повышением температуры облучения понижается концентрация и увеличивается в размерах, по границам обнаружена мелкодисперсная α-фаза, обогащенная хромом, которая при повышенных температурах исчезает, так же по границам зерен мартенсита наблюдается небольшое количество радиационных пор. Прошедшие изменения микроструктуры под воздействием нейтронного облучения не привели к существенным изменениям механических свойств. / The aim of the work is to establish the effect of neutron irradiation on the stability of the structure and phase state of the EP823 ferrite-martensitic steel. This work is devoted to the analysis of the effect of neutron irradiation on the phase and structural components of steel. The studies were carried out on samples of fuel rod shells irradiated as part of a materials science assembly in the BN-600 reactor at temperatures of 570, 600, 660 ℃ to damaging doses of 51.3, 75.1, and 81.1 dpa. The characteristics of structural components and secondary phases formed during irradiation were determined by metallography and stereometric analysis, and the characteristics of radiation porosity and dislocation density were evaluated. The studies were performed using a MIRA3 FEG-SEM scanning electron microscope equipped with secondary and reflected electron detectors and an x-Act 6 energy dispersive analysis of characteristic X-ray radiation from Oxford Instruments. Studies were also carried out on a transmission electron microscope of the JEM-2000EX company at an accelerating voltage of 100 kV in the transmission mode. Quantitative image processing to obtain the dimensional characteristics of the secretions was carried out using the software "Digital Photo Laboratory SIAMS Photolab", as well as using the software of the scanning electron microscope MIRE3 FEG-SEM. The study of steel X12NMVBFSR in the initial state showed that its structure consists of martensite, residual ferrite, large carbides based on Nb and along the boundaries of ferritic grains and martensitic rails, carbides of the M23C6 type are formed. After neutron irradiation, the content of carbides of the M23C6 type increases, a χ-phase is formed in the ferrite grains, in which the concentration decreases and increases in size with an increase in the irradiation temperature, a fine alpha-phase enriched in chromium is found along the boundaries, which disappears at elevated temperatures, as well as a small number of radiation pores are observed along the boundaries of martensite grains. The past changes in the microstructure under the influence of neutron irradiation did not lead to significant changes in the mechanical properties.

I dagsläget finns ca 600 000 ha Contortaskog i Sverige varav en stor del planterades runt 70- till 80-talet. Contorta har sitt ursprung i västra USA och Kanada och introducerades i Sverige som en lösning på en förutspådd fibersvacka. I dagsläget börjar en stor del av den inplanterade Contortan börjar bli så pass gammal att det går att ta fram sågade trävaror ur stocken men exakt vilka egenskaper svenskvuxen Contorta har inte helt redogjort. I denna studie har korrelationen mellan medelårsringsbredden, sommarvedsandelen, svällning och böjhållfastheten, e-modulen och densiteten undersökts. Dessutom undersöktes det om det finns en statistisk skillnad mellan de fyra växtplatserna hos Contortan i studien och hur Contorta skiljer sig mot svensk tall och gran. Korrelationen mellan medelårsringsbredden och böjhållfastheten var -0,33, densiteten -0,18 och E-modulen -0,42. För sommarvedsandelen var korrelationen till böjhållfastheten 0,11, densiteten 0,21 och E-modulen 0,06. För radiell respektive tangentiell svällning var korrelationen till böjhållfastheten -0,12 och -0,15, densiteten 0,01 och 0,11, E-modulen -0,29 och 0,27. För alla fyra växtplatser fanns det en statiskt signifikant skillnad mellan medelvärdena för alla undersökta variabler. Svensk tall och Gran har liknande samband. / Currently there is about 600 000 hectares of lodgepole pine forests in Sweden which of most were planted during the 1970s and -80s. Lodgepole pine is native species to western USA and Canada and was introduced in Sweden as an answer to an expected pulp-fiber volume depression. A big portion of these stands are now reaching maturing age for sawn timber product production, but little is known about lodgepole pine grown on Swedish soil. In this study, the correlation between the mean tree ring width, latewood ratio, swelling and the bending strength, modulus of elasticity (MOE) and density have been studied, if there is a statistically significant difference between the four different geographical stands the lodgepole pine in this study are stemming from and lastly how Swedish grown lodgepole pine differs from the traditional Swedish construction lumbers Scots pine and Norway spruce. The correlation between the mean ring width and the bending strength was -0,33, the density -0,18 and the MOE -0,42. For the latewood ratio and the bending strength it was 0,11, the density 0,21 and the MOE 0,06. For the radial and tangential swelling respectively it was -0,12 and -0,15 for the bending strength, 0,01 and 0,11 for the density and -0,29 and 0,27 for the MOE. For all four different growth stands there was a statistically significant difference between the means for all studied variables. The relationships for both Scots pine and Norway spruce show similar magnitudes and directions.

Thèse de recherche en chimie dans le domaine des polymères / Les polymères photostimulables sont une classe spécifique de polymères stimulables capables de subir un changement de conformation sous l’action de l’irradiation lumineuse. La lumière est un stimulus externe physique pouvant avoir un impact sur un matériau sans modifier directement sa composition chimique. De plus, la taille d’un faisceau lumineux comme le laser peut atteindre des dimensions de l’ordre de la centaine de nanomètres, permettant son utilisation pour les travaux de précision. Enfin, pouvoir allumer et éteindre la source de lumière de manière instantanée rend ce stimulus attrayant pour un vaste choix d’applications en raison de la possibilité de contrôler avec précision les échelles de temps d’utilisation du stimulus. C’est pourquoi les chercheurs s’intéresse à la lumière en tant que stimulus et à ses potentielles applications pour les polymères stimulables. Dans les deux premiers chapitres de ce manuscrit, la lumière sera utilisée pour induire indirectement une réponse au sein de polymères thermostimulables. Pour cela, des matériaux photothermiques capables de convertir la lumière en chaleur seront combinés avec des polymères thermostimulables à base de microgels de poly(N-isopropylacrylamide) (PNIPAM) afin de préparer des matériaux composites. Ces types de matériaux sont déjà bien connus dans la littérature. Cependant, à l’échelle micrométrique, ils souffrent d’une mauvaise optimisation en raison de la ségrégation des matériaux lors de leur préparation. Le premier chapitre traitera tout d’abord de la préparation d’un tel composite à base de microgels de PNIPAM et de nanoparticules d’or (AuNPs). Différents paramètres permettant d’améliorer la dispersion des AuNPs dans les microgels seront identifiés dans le but d’optimiser la synthèse de ces matériaux composites. Ensuite, les microgels composites seront immobilisés en surface, et leur gonflement en surface en fonction de la température et de l’irradiation sera étudié à l’aide de la technique Surface Force Apparatus (SFA). Cette étude innovante rapporte pour la première fois la caractérisation quantitative du gonflement de polymères photo- et thermostimulables immobilisés en surface à l’échelle du nanomètre. En effet, ce type de système n’a jusqu’à maintenant été étudié que de manière qualitative. Dans un second chapitre, les AuNPs qui ont servi de nanoparticules photothermiques modèles ont été remplacées par la polydopamine (PDA), une nanoparticule aux propriétés photothermiques dont l’intérêt s’est développé plus récemment. La PDA, comme les AuNPs, interagit et se complexe avec les amines primaires contenus dans nos microgels de PNIPAM. Ainsi, les deux systèmes composites sont présumés similaires en termes de conformation et de structure. Les microgels composites à base de PDA ont été préparés dans des proportions équivalentes de nanoparticules photothermiques à celles à base de AuNPs de l’étude précédente, ce qui a permis leur comparaison. Les deux matériaux composites ont démontré des propriétés photothermiques similaires, avec cependant des performances légèrement supérieures pour les microgels composites à base de PDA. Utilisant des sources d’irradiation de même puissance, la PDA, lorsqu’irradiée à 360 nm, semble démontrer des propriétés photothermiques environ 25% supérieures à celles des AuNPs sphériques irradiées à leur longueur d’onde de résonance plasmonique. Bien qu’étant supérieur en termes de propriétés photothermiques, le gonflement en surface des microgels composites à base de PDA était inférieur à celui des microgels composites à base d’AuNPs. Cette différence de comportement s’explique par une densité de greffage des microgels composites à base de PDA inférieure à la densité de greffage des microgels composites à base d’AuNPs. Il en résulte une augmentation de l’espace adjacent pour les microgels moins densément greffés pouvant gonfler dans toutes les directions contrairement à une densité de greffage importante qui favorise le gonflement des microgels de manière perpendiculaire au substrat. Enfin, dans le troisième chapitre, des brosses de polymères aux propriétés réversiblement photo-dimérisables ont été préparées. Pour cela, des chaînes pendantes de coumarine ont été introduites dans les brosses de polymères. La coumarine est un groupement qui peut subir une dimérisation sous l’effet de la lumière UVA (λUVA > 310 nm) et peut se dédimériser réversiblement sous l’irradiation des UVC (λUVC < 260 nm). La photo-dimérisation de la coumarine ne peut avoir lieu que si elle respecte certains critères stricts, à savoir une orientation parallèle ou antiparallèle des groupements de coumarine et une distance de séparation inférieure à 4,2 Å. Ainsi, l’immobilisation de la coumarine sur une surface peut affecter la photo-dimérisation en raison de la difficulté de contrôler la distance de séparation entre les groupements de coumarine situés sur les chaînes de polymères adjacentes immobilisées en bout de chaînes. Dans cette partie, la propriété de photo-dimérisation réversible des brosses de polymères contenant des chaînes pendantes de coumarine a ainsi été étudiée en fonction de la distance de séparation entre les chaînes polymériques. De plus, la caractérisation de la capacité de gonflement de la couche de polymères ainsi obtenue dans l’eau a permis d’estimer la nature de la photo-dimérisation des chaînes polymériques, qui est favorisée de manière intermoléculaire pour un greffage dense de chaînes de polymères. / Photo-responsive polymers are a specific class of stimuli-responsive polymers which undergo conformational changes under light irradiation. Light is an external physical stimulus which can impact a medium without affecting its chemical composition. Width beam can be as low as a few hundreds of nanometers, which makes it usable for precision work. Furthermore, the capacity to turn off and on the light source instantaneously makes it very attractive for all kind of applications because of the possibility to control the timescale of the stimulus. Therefore, the work will focus on the study of light as a stimulus and its potentials of applications in order to trigger a response in stimuli-responsive polymers either directly, or indirectly. In the first two chapters of this manuscript, light will be used to trigger indirectly a response in thermo-responsive polymers. For this, photothermal materials that can convert light into heat will be combined with thermo-responsive polymers based on poly(N-isopropylacrylamide) (PNIPAM) microgels in order to prepare composite materials. These types of materials are already well known in the literature. However, at the microscale level, they suffer from poor optimization because of segregation of materials during the preparation process. The first chapter will treat the preparation of such composite based on PNIPAM microgels and gold nanoparticles (AuNPs). Different parameters allowing the improvement of AuNPs dispersion in the microgels will be identified in order to optimize the synthesis of the composite materials. Then, the composite microgels were immobilized on surface, and their swelling as a function of the temperature, and triggered by light were studied using the Surface Force Apparatus (SFA). This innovative study reports the first quantitative characterization of the swelling of photo- and thermo-responsive polymers immobilized on surfaces and at the nanometer scale. Indeed, these systems have been reported multiple times in the literature. However, the nature and scale at which these materials are studied were so far limited to qualitative characterizations only. In the second chapter, the AuNPs which served as model photothermal nanoparticles were swapped with polydopamine (PDA), a nanoparticle with photothermal properties whose interest has recently grown. PDA, like AuNPs, can interact and complex with primary amines that are present in our PNIPAM microgels. Thus, both composite systems were expected to be similar in terms of conformation and structure. The PDA containing composite microgels were prepared using equivalent proportions of photothermal nanoparticles compared to the precedent study, allowing a comparison of both PDA and AuNPs containing composite microgels. Both composites demonstrated similar photothermal properties, albeit a slightly better performance for the composite microgels based on PDA. Using light sources of equivalent power, PDA demonstrated photothermal properties when irradiated at 360 nm, approximately 25% superior than that of spherical AuNPs irradiated at their localized surface plasmon resonance. Despite being slightly superior in terms of photothermal responsive properties, the surface swelling of the PDA containing composites were inferior to that of AuNPs containing composites because of differences in terms of grafting caused by differences of interactions between the composites with silica-based substrates. Finally, in the third chapter, polymer brushes with reversibly photo-dimerizable properties were prepared. For this purpose, pendant chains of coumarin were introduced into polymer brushes. Coumarin is a functional group that can undergo dimerization under the influence of UVA light (λUVA > 310 nm) and can reversibly dedimerize upon irradiation with UVC (λUVC < 260 nm). The photo-dimerization of coumarin can only occur if strict criteria are met, including a parallel or antiparallel orientation of the coumarin groups and a separation distance of less than 4.2 Å. Thus, the immobilization of coumarin on a surface can affect the photo-dimerization due to the difficulty of controlling the separation distance between the coumarin groups located on end-tethered adjacent polymer chains. In this part, the reversible property of photo-dimerization of polymer brushes containing pendant chains of coumarin was studied as a function of the separation distance between the polymer chains. Furthermore, the characterization of the swelling capacity of the resulting polymer layer in water allowed us to assess the nature of the photo-dimerization of the polymer chains, which is favored in an intermolecular manner for densely grafted polymer chains.

Une fois ingérées par un insecte sensible, les toxines insecticides du bacille de Thuringe doivent être activées par les protéases intestinales de cet insecte. Leur premier domaine, un ensemble de sept hélices-α amphipathiques, est responsable de leur insertion dans la membrane luminale de certaines cellules de l’intestin médian, ce qui crée des pores peu sélectifs. La toxicité et la capacité à former des pores d’une telle toxine, la Cry9Ca, de ses mutants simples R164A et R164K et d’un fragment de 55 kDa résultant d’un clivage protéolytique au niveau de son résidu 164 ont été étudiées à l’aide d’une combinaison de modélisation par homologie, de bioessais, d’expériences de gonflement osmotique avec des vésicules de membrane en bordure en brosse de larves de sphinx du tabac et de mesures électrophysiologiques sur des intestins isolés. Ni les mutations simples ni le clivage protéolytique n’ont altéré la toxicité de la Cry9Ca. Dans une solution à faible force ionique, toutefois, la formation des pores dépend fortement du pH : une augmentation de celui-ci de 6,5 à 10,5 a entraîné une baisse irrégulière et par étapes successives de la perméabilité membranaire. Les quatre préparations de toxine ont néanmoins dépolarisé la membrane apicale d’intestins médians fraîchement isolés baignant dans une solution contenant 122 mM de KCl à pH 10,5. L’activité de la Cry9Ca, et des mutants R164A et R164K, a été grandement stimulée lorsque les expériences ont été effectuées en présence de suc intestinal, de lipides extraits d’un volume équivalent de suc intestinal ou d’un cocktail d’inhibiteurs de protéases solubles dans l’eau. De plus, le rôle des boucles inter-hélicales du Domaine I lors de l’insertion dans la membrane a été étudié avec des mutants doubles de la Cry9Ca dont les mutations introduisaient, neutralisaient ou renversaient une charge électrique. À l’exception de trois d’entres eux, tous ces mutants ont conservé une toxicité et une capacité à former des pores comparables à celles de la toxine parentale. L’ensemble de ces résultats suggère que le micro-environnement de l’intestin médian contribue à minimiser l’influence des charges de surface portées par les résidus des boucles inter-hélicales du Domaine I sur la capacité des toxines du bacille de Thuringe à former des pores. Il indique aussi que, d’une part, selon le site de clivage et les conditions expérimentales utilisées, des protéolyses supplémentaires de la toxine Cry9Ca activée peuvent soit stimuler, soit nuire à son activité et que, d’autre part, le suc intestinal du sphinx du tabac contient probablement un inhibiteur de protéases qui pourrait jouer un rôle important dans l’activité des toxines du bacille de Thuringe. / Once ingested by susceptible insects, Bacillus thuringiensis insecticidal toxins must be activated by the insect’s intestinal proteases. Their first domain, a bundle of seven amphipathic -helices, is responsible for their insertion into the luminal membrane of midgut cells, thereby creating poorly selective pores. The toxicity and pore-forming ability of one such toxin, Cry9Ca, its single-site mutants, R164A and R164K, and of the 55-kDa fragment resulting from its proteolytic cleavage at residue 164 were investigated using a combination of homology modeling, bioassays, osmotic swelling experiments with Manduca sexta larval midgut brush border membrane vesicles and electrophysiological measurements on isolated midguts. Neither the single mutations nor the proteolytic cleavage altered Cry9Ca toxicity. In low ionic strength solutions however, pore formation was highly dependent on pH: increasing pH from 6.5 to 10.5 resulted in an irregular step-wise decrease in membrane permeabilization. All four toxin preparations nevertheless depolarized the apical membrane of freshly isolated midguts bathing in a solution containing 122 mM KCl at pH 10.5. The activity of Cry9Ca, R164A and R164K was greatly enhanced when the experiments were conducted in the presence of midgut juice, the lipids extracted from an equivalent volume of midgut juice or a cocktail of water-soluble protease inhibitors. Additionally, the role of the interhelical loops of Domain I in membrane insertion was investigated with Cry9Ca double mutants with mutations that either introduced, neutralized or reversed an electrical charge. All but three mutants retained a toxicity and a pore-forming ability that were comparable to those of their parental toxin. Overall, the results suggest that the midgut microenvironment contributes to minimizing the influence of surface charges carried by Domain I interhelical loop residues on B. thuringiensis toxins pore-forming ability. They also indicate that, depending on the cleavage site and on the experimental conditions used, further proteolysis of the activated Cry9Ca toxin can either stimulate or be detrimental to its activity and that M. sexta midgut juice probably contains protease inhibitors that could play a major role in the activity of B. thuringiensis toxins in the insect midgut.

Les alliages binaires FeCr de structure FM (ferrito/martensitique) sont actuellement les candidats les plus prometteurs comme matériaux de structure pour les réacteurs rapides refroidis au sodium et les futurs systèmes de fusion. Cependant, l'impact de Cr sur l'évolution de la microstructure irradié dans ces matériaux n’est pas bien compris. De plus, particulièrement pour les applications de fusion, le scénario de dégâts d'irradiation devrait être compliquée en outre par la présence de grandes quantités d'hélium produit par transmutation nucléaire (~ 10 appm He / dpa). Dans ce contexte, une étude spécifique des effets de l'irradiation ionique (influence du Cr et de l’He sur l’évolution de la microstructure) a été menée à 500 ° C sur une grande variété d’alliages FeCr de haute pureté (à teneur en Cr allant de ~ 3 wt.% À 14 wt.%) ainsi que sur du Fe pur. Les irradiations ont été effectuées à l'aide ions Fe, en mode mono-faisceau et mode dual-beam (irradiation par des ions Fe et co-implantation d'He) afin de pouvoir séparer le dommage ballistique de l’implantation couplée avec de l’He. Trois différentes doses ont été étudiées: dose élevée (157 dpa, avec 17 appm He / dpa), dose intermédiaire (45 dpa, avec 57 appm He / dpa) et in situ à faible dose (0,33 dpa, avec 3030 appm He / dpa). Les expériences ont été effectuées en utilisant l'installation JANNuS triple faisceau du CEA-Saclay et la plateforme in-situ du CSNSM-Orsay. L’évolution microstructurale des échantillons est essentiellement faite par MET, SAT et par EDS en mode STEM. Les principaux résultats sont les suivants : 1) L’étude détaillée de la population des cavités dans du Fe irradié à forte dose a révélé une forte réduction du gonflement du fait de l'ajout d’He. Une réduction drastique de la taille des cavités en dépit d’une densité plus élevée a été observée. Ce comportement a été observé tout au long zone irradié, jusqu’au pic d’endommagement. 2) La microstructure de cavités a également été étudiée dans les alliages FeCr irradiés en double faisceau à forte dose, et les résultats ont été comparés à ceux obtenus dans le Fe pur. L'analyse a été effectuée à une profondeur intermédiaire de 300 à 400 nm sous la surface (pour éviter les effets des interstitiels injectés et les effets de surface), correspondant à 128 dpa, 13 appm He / dpa. L’étude par TEM a montré que l'addition de petites quantités de Cr, aussi basse que 3wt.%, est très efficace pour réduire fortement le gonflement. Une réduction drastique de la taille des cavités a été mise en évidence. Par exemple, la taille moyenne des cavités pour l’alliage Fe3% Cr est de l’ordre de 0,9 nm alors qu’elle est voisine de 6,8 nm pour le Fe pur. De plus, la variation du gonflement en fonction de la teneur en Cr n’est pas monotone et présente un maximum local à environ 9 -. 10wt% Cr. 3) Le couplage des différentes techniques d’analyse, MET classique, STEM/EDS et analyse SAT appliqué à l’étude des alliages FeCr irradiés à faible et moyenne dose révèle la présence de zones enrichies en Cr sur le plan d’habitat des boucles de dislocation. Ce phénomène est relié à un phénomène de ségrégation induite par irradiation (RIS) de Cr au voisinage du coeur des boucles de dislocation. Quand la boucle se développe sous irradiation, les zones de ségrégation ne peuvent probablement pas se redissoudre du fait de la présence d'impuretés telles que le C. Lorsque les boucles sont imagées par MET, ces zones enrichies produisent des franges de contraste au voisinage du plan de la boucle. Une estimation quantitative de cet enrichissement a été déduit par STEM / EDS et l'SAT. La teneur en Cr dans ces domaines se situe entre 23 -. 35% par EDS et 22 % par SAT, ce qui est bien en dessous de la teneur en Cr de la phase α’ riche en Cr. / FeCr binary alloys are a simple representative of the reduced activation ferritic/martensitic (F-M) steels, which are currently the most promising candidates as structural materials for the sodium cooled fast reactors (SFR) and future fusion systems. However, the impact of Cr on the evolution of the irradiated microstructure in these materials is not well understood in these materials. Moreover, particularly for fusion applications, the radiation damage scenario is expected to be complicated further by the presence of large quantities of He produced by the nuclear transmutation (~ 10 appm He/dpa). Within this context, an elaborate ion irradiation study was performed at 500 °C on a wide variety of high purity FeCr alloys (with Cr content ranging from ~ 3 wt.% to 14 wt.%) and a bcc Fe, to probe in detail the influence of Cr and He on the evolution of microstructure. The irradiations were performed using Fe self-ions, in single beam mode and in dual beam mode (damage by Fe ions and co-implantation of He), to separate ballistic damage effect from the impact of simultaneous He injection. Three different dose ranges were studied: high dose (157 dpa, 17 appm He/dpa for the dual beam case), intermediate dose (45 dpa, 57 appm He/dpa for dual beam case) and in-situ low dose (0.33 dpa, 3030 appm He/dpa for the dual beam case). The experiments were performed at the JANNuS triple beam facility and dual beam in situ irradiation facility at CEA-Saclay and CSNSM, Orsay respectively. The microstructure was principally characterized by conventional TEM, APT and EDS in STEM mode. The main results are as follows: 1) A comparison of the cavity microstructure in high dose irradiated Fe revealed strong swelling reduction by the addition of He. It was achieved by a drastic reduction in cavity sizes and an increased number density. This behaviour was observed all along the damage depth, upto the damage peak. 2) Cavity microstrusture was also studied in the dual beam high dose irradiated FeCr alloys, and the results were compared to bcc Fe. The analysis was performed at an intermediate depth 300 – 400 nm below the surface (to avoid injected interstitial effect and surface effects), corresponding to 128 dpa, 13 appm He/dpa. TEM study revealed that the addition of small quantities of Cr, as low as 3wt.%, is highly efficient in strongly reducing void swelling. It was achieved by a drastic reduction of cavity sizes. For instance, average cavity size in Fe3%Cr was 0.9 nm as opposed to 6.8 nm in bcc Fe. Furthermore, the variation of void swelling as a function of Cr content is non-monotonic, with alocal maxima around 9 - 10wt.%Cr. 3) Coupling of conventional TEM, STEM/EDS and APT analysis on low and intermediate dose irradiated FeCr alloys revealed the presence of Cr enriched zones on the habit plane of the dislocation loops. This is expected to be due to radiation induced segregation (RIS) of Cr close to the core of the loops. As the loop grows under irradiation, the segregated areas are probably prevented from re-dissolution by impurity elements such as C. When imaged by TEM using classical diffraction contrast imaging techniques, these enriched zones produce displacement fringe contrast on the loop plane. A quantitative estimate of this enrichment was deduced by STEM/EDSand APT. The Cr content in these areas was between 23 - 35 at.% measured by EDS and 22 ± 2 at.% obtained by APT, whichis well below the Cr content of the Cr-rich α’ phase.

<p style="text-align: justify;">U ovom radu sintetisani su hidrogelovi na osnovu akrilamida i akrilne kiseline, radikalnom polimerizacijom, primenom konvencionalne i mikrotalasne metode sinteze. Varirani su početni odnosi monomera i udeo umreživača, u cilju ispitivanja uticaja sastava reakcione sme&scaron;e na svojstva dobijenih hidrogelova. Optimizovani su uslovi sinteze u mikrotalasnom polju kao brže, jednostavnije i ekonomičnije metode. U cilju uspostavljanja korelacije između mehanizma sinteze, strukture i svojstava dobijenih hidrogelova, primenom relevantnih metoda karakterizacije, upoređena su apsorpciona, reolo&scaron;ka, toplotna i strukturna svojstva hidrogelova dobijenih dvema metodama.&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Ustanovljeno je da se mikrotalasnom metodom sinteze na brži i jednostavniji način uz smanjen utro&scaron;ak vremena i energije dobijaju hidrogelovi konkurentni onima koji se dobijaju konvencionalnim zagrevanjem u vodenom rastvoru. Drugi deo doktorata obuhvata sintezu hidrofilnih polimernih mreža na osnovu natrijum karboksimetilceluloze (NaCMC) i karboksilnih kiselina, od kojih je jedna serija sintetisana prožimanjem linearnim kopolimerima akrilamida i akrilne kiseline u cilju povećanja potencijala primene u floku-lacione svrhe. Rezultati ispitivanja svojstava bubrenja, strukturnih toplotnih i flokulacionih svojstava pokazali su međusobno slaganje. Dobijeni rezultati pokazali su da od primenjenih karboksilnih kiselina, linunska kiselina u udelu od 15% u odnosu na masu NaCMC daje hidrogelove najboljih svojstava. Kombinacijom ove mreže sa kopolimerom akrilamida i akrilne kiseline u masenom odnosu 10/90, stvara se teorijska platforma za dobijanja flokulanta koji bi mogao da pokaže visoku efikasnost u preči&scaron;ćavanju vode u kojoj dominiraju pozitivno naelektrisane čestice, pravilnim izborom parametara flokulacije.</p> / <p>In this paper, hydrogels based on acrylamide and acrylic acid were synthesized using conventional and microwave synthetic methods via free-radical polymerization. The initial monomers ratio and amount of crosslinking agent were varied in order to investigate the effect of the composition of the reaction mixture on the properties of the obtained hydrogels. The conditions of synthesis in the microwave field as faster simpler and more economical method have been optimized. In order to establish a correlation between the mechanism of synthesis, structure and properties of the obtained hydrogels using the relevant methods of characterization, the absorption, rheological, thermal and structural properties of the hydrogels obtained by the two methods were compared. It has been found that the microwave synthesis is a faster and simpler method, which enables reduced consumption of time and energy and produces hydrogels competitive to those ones obtained by conventional heating in aqueous solution. The second part of the thesis includes the synthesis of hydrophilic polymer networks based on sodium carboxymethylcellulose (NaCMC) and carboxylic acids, whereby one series is synthesized by interpenetration of the network using the linear acrylamide and acrylic acid copolymers in order to increase the potential application of hydrogels for flocculation purposes. The results of measurements of swelling, structural, thermal and flocculation properites have shown mutual agreement. The obtained results have shown that among applied carboxylic acids, citric acid in the amount of 15% per mass of NaCMC, has given the hydrogels with the best properties. The Combination of this network with a copolymer of acrylamide and acrylic acid in a mass ratio of 10/90 has created a theoretical platform for the production of flocculant which could show high efficacy in purifying of water dominated by positively charged particles.</p>

Die Höhe des optimalen zerebralen Perfusionsdruckes nach schwerem Schädel-Hirn-Trauma wird kontrovers diskutiert. Während im sogenannten Lund-Konzept ein niedriger Perfusionsdruck angestrebt und die Gabe von Katecholaminen aufgrund potentieller zerebraler vasokonstringierender und weiterer Nebeneffekte vermieden wird, befürwortet das CPP-Konzept nach Rosner eine Anhebung des zerebralen Perfusionsdruckes, wenn notwendig unter intravenöser Gabe von Katecholaminen. Vor diesem Hintergrund galt es, in einem experimentellen Schädel-Hirn-Trauma- Modell der Ratte (Controlled Cortical Impact Injury) den Bereich des optimalen zerebralen Perfusionsdruckes nach traumatischer Hirnkontusion zu ermitteln und den Effekt von Katecholaminen auf den posttraumatischen zerebralen Blutfluss und die Entwicklung des sekundären Hirnschadens zu untersuchen. Die wesentlichen Ergebnisse dieser Arbeit lassen sich wie folgt zusammenfassen: In der Akutphase nach Hirnkontusion liegt der Bereich des zerebralen Perfusionsdruckes, welcher die Entwicklung des Kontusionsvolumens nicht beeinflusst, zwischen 70 und 105 mm Hg. Eine Senkung des Perfusionsdruckes unterhalb bzw. Anhebung oberhalb dieser Schwellenwerte vergrößert das Kontusionsvolumen. Die Anhebung des Blutdruckes mittels intravenöser Infusion von Dopamin oder Noradrenalin führt sowohl in der Frühphase als auch in der Spätphase nach Trauma (4 Stunden bzw. 24 Stunden nach kortikaler Kontusion) zu einem signifikanten Anstieg im kortikalen perikontusionellen Blutfluss und in der Hirngewebe-Oxygenierung. Die durch Anhebung des zerebralen Perfusionsdruckes auf über 70 mm Hg induzierte Verbesserung des posttraumatischen zerebralen Blutflusses bewirkte jedoch keine Reduzierung der Hirnschwellung. Für eine Katecholamin-induzierte zerebrale Vasokonstriktion nach kortikaler Kontusion gibt es keinen Anhalt. Um die Entwicklung des sekundären Hirnschadens nach kortikaler Kontusion zu minimieren, sollte der zerebrale Perfusionsdruck nach traumatischem Hirnschaden nicht unterhalb 70 mm Hg liegen. Eine Anhebung des Perfusionsdruckes auf über 70 mm Hg erscheint nicht notwendig oder vorteilhaft zu sein. Wenn notwendig, kann sowohl in der Früh- als auch Spätphase nach Trauma der zerebrale Perfusionsdruck mittels intravenöser Gabe von Katecholaminen angehoben werden. / The optimum cerebral perfusion pressure after severe traumatic brain injury remains to be controversial. In the Lund concept a relatively low cerebral perfusion pressure is preferred, and administration of catecholamines is avoided due to potential catecholamine-mediated cerebral vasoconstriction and other side effects. In contrast, the CPP concept of Rosner recommends elevation of cerebral perfusion pressure, if needed by intravenous administration of catecholamines. Based on this, in an experimental model of traumatic brain injury of the rat (Controlled Cortical Impact Injury) the optimum range of cerebral perfusion pressure after traumatic brain contusion and the effects of catecholamines on posttraumatic cerebral perfusion and development of secondary brain injury were investigated. The most significant results can be summarized as follows: In the acute phase after brain contusion the range of cerebral perfusion pressure that does not affect the development of posttraumatic contusion volume was found to be between 70 and 105 mm Hg. Reduction of the cerebral perfusion pressure below or elevation above these thresholds increases contusion volume. Elevation of blood pressure by intravenous infusion of dopamine or norepinephrine during the early (4 hours) as well as late (24 hours) phase after trauma results in a significant increase in pericontusional blood flow and brain tissue oxygenation. The increase in cerebral blood flow by elevating cerebral perfusion pressure above 70 mm Hg did not decrease cerebral edema formation. There was no evidence of a catecholamine-induced cerebral vasoconstriction after cortical contusion. In order to minimize secondary brain injury after cortical contusion, cerebral perfusion pressure should not fall bellow 70 mm Hg. However, a further active elevation of cerebral perfusion pressure does not appear necessary or beneficial. If needed cerebral perfusion pressure can be elevated by administration of catecholamines in the early as well late phase after trauma.

<p>A new kind of lipid/polymer composite particle, consisting of a biodegradable polymer matrix with well-defined lipid domains, has been created. The lipid used is the water-swelling lipid monoolein (MO), which forms a reversed bicontinuous cubic diamond structure in aqueous solutions. The polymer is poly(d,l-lactide-co-glycolide) (PLG), which degrades into water-soluble monomers through hydrolysis. This new particle might be a good alternative for encapsulation of active substances intended to be released over a longer period of time, i.e. sustained/retained/controlled release.</p><p>To prepare such particles can be difficult. Suitable phase behaviour and a solvent with the right properties are needed. For this reason, the phase behaviours of several different lipid/polymer/solvent/water systems have been explored. From the phase behaviour of a suitable system (i.e. MO/PLG/ethyl acetate/water), a route for formation of lipid/polymer composite particles has been deduced. Particles have been formed and distinct, water-swelling, lipid domains have been confirmed by characterization by means of confocal laser scanning probe microscopy (CLSM). </p><p>The sample preparation process has been automated and a method based on using a robotic liquid handler has been developed. Phase diagrams have been determined by examination of macroscopic behaviours and the microstructures of the phases have been studied by small- and wide-angle X-ray scattering (L₃, V₂, L_α, L), nuclear magnetic resonance self-diffusion (L, L₃), viscosimetry (L) and rheology (L). Several different theoretical models have been applied for interpretation of the results. For example, the swelling of the reversed bicontinuous cubic phases and the sponge phase have been modelled by applying the theory of infinite periodical minimal surfaces, the sponge phase has been shown to be bicontinuous according to the theory of interconnected rods and the phase behaviour of the polymer has been described by the Flory-Huggins theory. The main focus of this work (4/5) concerns phase studies in multicomponent systems from a physical-chemical point of view.</p>

A new kind of lipid/polymer composite particle, consisting of a biodegradable polymer matrix with well-defined lipid domains, has been created. The lipid used is the water-swelling lipid monoolein (MO), which forms a reversed bicontinuous cubic diamond structure in aqueous solutions. The polymer is poly(d,l-lactide-co-glycolide) (PLG), which degrades into water-soluble monomers through hydrolysis. This new particle might be a good alternative for encapsulation of active substances intended to be released over a longer period of time, i.e. sustained/retained/controlled release. To prepare such particles can be difficult. Suitable phase behaviour and a solvent with the right properties are needed. For this reason, the phase behaviours of several different lipid/polymer/solvent/water systems have been explored. From the phase behaviour of a suitable system (i.e. MO/PLG/ethyl acetate/water), a route for formation of lipid/polymer composite particles has been deduced. Particles have been formed and distinct, water-swelling, lipid domains have been confirmed by characterization by means of confocal laser scanning probe microscopy (CLSM). The sample preparation process has been automated and a method based on using a robotic liquid handler has been developed. Phase diagrams have been determined by examination of macroscopic behaviours and the microstructures of the phases have been studied by small- and wide-angle X-ray scattering (L3, V2, Lα, L), nuclear magnetic resonance self-diffusion (L, L3), viscosimetry (L) and rheology (L). Several different theoretical models have been applied for interpretation of the results. For example, the swelling of the reversed bicontinuous cubic phases and the sponge phase have been modelled by applying the theory of infinite periodical minimal surfaces, the sponge phase has been shown to be bicontinuous according to the theory of interconnected rods and the phase behaviour of the polymer has been described by the Flory-Huggins theory. The main focus of this work (4/5) concerns phase studies in multicomponent systems from a physical-chemical point of view.