In intra-arterial radioembolization, nano- and micro-scaled carriers are used in patients with liver tumors that cannot be removed by surgery to deliver various radioisotopes with the aim of improving the outcome of tumor radiotherapy, of minimizing dose to healthy tissue, and of improving the quality of the diagnosis and imaging. In this technique, radioisotopes are incorporated in either nanospheres or microspheres for delivery. The synthesis of these maybe performed either using the isotope in its radioactive form or nonradioative form; however, if the synthesis is performed using non-radioactive isotopes, a subsequent activation by neutron bombardment in a nuclear reactor is required. This investigation focused on neutron-activation simulations using computer models of microspheres loaded with holmium acetylacetonate (HoAcAc) complex in a polymeric matrix that are used for intra-arerial radioembolization therapy of liver cancer. The polymer matrix is made of poly (L-lactic acid) (PLLA) which is both biodegradable and biocompatible. In addition, as a requirement for therapeutic applications of these microspheres, not only their diameter must be within a range between 20 and 50 micrometers, but also before administration to a patient, they must be neutron-activated by turning holmium-165 into holmium-166. The main objective of this investigation was to minimize the energy deposited by neutrons and gammas produced by fission and neutron activation reactions that would result in damages to both the microsphere's polymeric matrix and holmium complex. To accomplish this objective, Monte Carlo N-Particle models were created to perform the following simulations: (1) microspheres loaded with a HoAcAc complex in a polymeric matrix were exposed to a neutron flux in the thermal column of a TRIGA reactor while arranged in a sheet-shaped packing configuration, and, similarly, (2) while arranged in a pile-shaped packing configuration, microspheres also loaded with a HoAcAc complex in a polymeric matrix were also exposed to the same neutron flux in the thermal column. Then, results from both types of simulations were analyzed and were compared. / Graduation date: 2011 / Access restricted to the OSU Community at author's request from Jan. 19, 2011-Jan. 19, 2013

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Cette thèse traite de l'effet de l'incorporation des laitiers des hauts fourneaux (LHF) sur la microstructure et la durabilité des bétons à Ultra Haute Performance (BUHP) avec et sans activation. Trois taux de substitution du ciment par des LHF sont explorés (30%, 50% et 80%). Les résultats montrent qu'une teneur de 30% de laitier améliore légèrement la résistance à la compression, alors qu’avec 50% et 80% de LHF, la résistance à la compression chute significativement. A 3 jours, lorsque la teneur en LHF augmente, la porosité du béton augmente. A 90 jours, la réaction des LHF induit une diminution de la porosité capillaire et le réseau poreux devient plus fin. Ainsi, la perméabilité au gaz et la diffusion des ions chlore diminuent significativement. Les résultats montrent aussi que tous les bétons testés ont une profondeur de carbonatation similaire, après une année d’exposition au CO2. En effet, la diminution de la porosité, due à l’ajout des LHF est équilibrée par la diminution du pH, qui favorise la diffusion de CO2. Pour ce qui concerne l'activation, les résultats montrent que l'activation chimique/thermique des BUHP à fort dosage en LHF améliore les propriétés microstructurales, mécaniques et de durabilité du béton. D’un point de vue environnemental et en considérant l’unité fonctionnelle « 1 m3 d’un BUHP à 150 MPa », la substitution partielle du ciment par des LHF diminue les impacts environnementaux du BUHP et c’est malgré l’activation thermique. / This thesis deals with microstructural and durability performances of environmentally friendly Ultra-High Performance Concrete (UHPC) by integrating high volumes of Blast Furnace Slag (BFS) with and without activation. Three substitution rates of cement by slag are used (30%, 50% and 80%). Results show that a slag content of 30% improves slightly the compressive strength of UHPC whereas the strength of UHPCs containing 50% and 80% of slag are significantly reduced particularly at early age. At 3 days when the slag content increases, the porosity of UHPC mixtures with high slag contents increases. In contrast, at 90 days the volume of capillary pores decreases greatly and the global pores network becomes finer when cement is substituted by BFS. This results in decreasing gas permeability coefficients around (30-61%) and chloride diffusion (up to 4 times). Results show also that all tested UHPCs have quite the same CO2 depths after exposure of 1 year. Indeed, the decrease of porosity due to slag incorporation, is balanced by the decrease of pH which promotes CO2 diffusion. The chemical/thermal activation improves the packing density and the mechanical and durability properties of UHPC. From an environmental standpoint and considering the functional unit “1 m3 of UHPC with 150 MPa”, the partial substitution of cement with BFS decreases the environmental impacts of UHPC, even for thermally activated blended UHPCs.

archives@tulane.edu / 1 / Aibolat Koishybay

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The Luteinizing hormone receptor (LHR) belongs to the G protein-coupled receptor family, asdo the other glycoprotein hormone receptors for FSH, TSH, and CG. The LHR comprises twohalves of ~350 amino acids: an extracellular hormone binding exodomain and a seventransmembrane-spanning endodomain responsible for signal generation. Hormone binds to theexodomain with high affinity, and the resulting conformational changes in thehormone/exodomain complex modulate the endodomain to generate hormone signals. Hormonebinding to an LHR produces hormonal signals (cis-activation), but it is not known whether aliganded LHR could activate other unoccupied LHRs (trans-activation). The LHR activates bothadenylyl cyclase and phospholipase C??. This dissertation shows that trans-activation of the LHRleads to the activation of adenylyl cyclase to induce cAMP but not to the activation ofphospholipase C?? to induce the inositol phosphate signaling. Trans-activation offers amechanism of signal amplification at the receptor level and also provides a mechanism ofmultiple signal generation for a liganded LHR to cis-activate phospholipase C?? and transactivateadenylyl cyclase. Also coexpression of Gi2 with a constitutively activating LHR(Asp578Gly), the most common mutation of male-limited precocious puberty, shows that Gi2could completely inhibit cAMP induction by the LHR mutant. Experiments using the carboxylterminal region of G protein ?? subunits demonstrate that LHR has overlapping binding sites forG?? subunits Gs and Gi2.

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