Before the beginning of digital-computers era, a lot of research was carried out in order to find electric circuits the governing equations of which were analogous to the ones of mechanical systems. The mentioned circuits were called ectro-mechanical analogs. They were used as analogical computers for the simulation and the design of mechanical systems. The actual technological development of piezoelectric actuators, which are devices able to efficiently transduce energy between the electrical and mechanical form, induced us to consider again those electro-mechanical analogs in order to create coupled piezo-electro-mechanical systems. Our idea is that the coupling between electro-mechanical phenomena is maximum when the propagation of both electrical and mechanical waves are governed by similar equations. Let us remark that because of the propagating mechanical wave-speed is much lower than the light-speed for every material, it is not possible to search for an efficient electro-mechanical coupling inside a piezoelectric continuum. Consequently circuits able to support the propagation of electric-potential waves have been considered. In this work, the equations for the elastica and for the plate are considered and their circuital analogs are derived using their finite-difference approximation. Afterwards, the coupling between the two structures is modelled considering piezoelectric actuators uniformly distributed on the mechanical system and connected to the nodes of the electric circuit. Then the electro-mechanical coupled equations are derived, and an analytical solution is found for a particular case. Finally some numerical simulations showing the efficiently energy exchange is presented. / Master of Science

Radar sounders (RS) are low frequency remote sensing instruments that profile the shallow subsurface of planetary bodies providing valuable scientific information. The prediction of the RS performance and the interpretation of the target properties from the RS data are challenging due to the complex electromagnetic interaction between many acquisition variables. RS simulations address this issue by forward modeling this complex interaction and simulating the radar response. However, existing simulators require detailed and subjective modeling of the target in order to produce realistic radargrams. For less-explored planetary bodies, such information is difficult to obtain with high accuracy. Moreover, the high computational requirements of conventional electromagnetic simulators prohibit the simulation of a large number of radargrams. Thus, it is not possible to generate and analyze a database of simulated radargrams representative of the acquisition scenario that would be very useful for both the RS design and the data analysis phase. To overcome these difficulties and to produce realistic simulated radargrams, this thesis proposes two novel approaches to the simulation and analysis of the radar response. The first contribution is a simulation approach that leverages the data available over geological analogs of the investigated target and reprocesses them to obtain the simulated radargrams. The second contribution is a systematic approach to the generation and analysis of a database of simulated radargrams representing the possible scenarios during the RS acquisition. The database is analyzed to predict the RS performance, to design the instrument parameters, and to support the development of automatic target detection algorithms. To demonstrate the proposed techniques the thesis addresses their use in two future RS instruments, which are at different phases of development: (1) the Radar for Icy Moons Exploration (RIME) and (2) a RS for Earth observation of the polar ice caps. The first contribution focuses on the analysis of the detectability of complex tectonic targets on the icy moons of Jupiter by RIME by simulating the radar response of 3D target models. The second contribution presents a feasibility study for an Earth orbiting RS based on the proposed simulation approaches.

No description available.

No description available.

The economic impact of metallic corrosion on global infrastructure, spanning pipeline networks, bridges, refineries, and automobiles, is considerable. In 2013, it accounted for 3.4% of the global GDP, totaling US$ 2.5 trillion. Organic coatings have gained significance as a prominent strategy to address this widespread issue. Polyaniline (PANI), a conducting polymer, has long been recognized as an effective anti-corrosion coating. This study explores the potential of polyaniline analogs and their nanocomposites as candidates for protective organic coatings in corrosion control applications. Initially, the investigation focuses on conducting polymers with side chains comprising long, branched alkyl groups as potential corrosion suppression coatings. These polymers, containing carbazole, phenothiazine, and phenoxazine cores, serve as analogs to polyaniline. Prepared through the Buchwald/Hartwig coupling reaction, these polymers demonstrated promising corrosion suppression capabilities, as tested by potentiodynamic polarization studies and electrochemical impedance spectroscopy (EIS). Morphological characterization using scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed that phenothiazine- and carbazole-containing polymers exhibit excellent corrosion resistance, with phenothiazine displaying a protection efficiency (PE) of 95.9% and 89.0% respectively, outperforming polyaniline coating. Further exploration involved the derivatives of phenothiazine-based PANI analogs, specifically poly(heterocyclic diphenylamine) (poly-HDA), prepared through the Buchwald/Hartwig coupling reaction. Evaluation through weight loss, potentiodynamic polarization, and EIS in a 3.5 wt.% NaCl solution showcased the reduced corrosion current density on surfaces coated with long-branched alkyl-substituted phenothiazine-based PANI analogs. Moreover, the reinforcement of the phenothiazine-based PANI analog polymer was achieved by creating an epoxy-based nanocomposite with 2,5-dimethyl-1,4-phenylenediamine functionalized graphene oxide (PT/DPPD-fGO) at varying concentrations into an epoxy anticorrosive coating for AISI 4130 steel from corrosion. Results from immersion in 5 % sodium chloride solution, coupled with standard electrochemical measurements, demonstrate that PT/DPPD-fGO effectively protects AISI 4130 steel from corrosion, with coatings containing 5 % PT/DPPD-fGO exhibiting the best corrosion performance among the tested specimens. The results indicate the potential of phenothiazine- and carbazole-based PANI analogs, along with their nanocomposites, as candidates for protective organic coatings in transportation, aviation, marine, and oil and gas industrial applications.

This research focused on the study of the amino sugar recycling and sialic acid degradation pathway as a possible entry point for N-acyl glucosamines for the production of sialic acid analogs. Meeting this objective would allow the development of a bacterial strain capable of producing non-natural nonulosonic acids that could be used in the development of medicines, vaccines or useful compounds for the study of interactions between pathogenic organisms and their host. The first step was to understand how N-acetyl-D-glucosamine-6-phosphate deacetylase reacts to different types of substrates in order to determine its tolerance to the size of acyl groups in acyl amino sugars. This was achieved by studying the enzymatic activity in an in vitro system. We determine that the enzyme has a preference for small and slightly bulky acyl groups. Then, an in silico docking modeling and an in vivo system experiment were carried out. These experiments allowed to confirm the previous results. The second project was carried out due to the uncertainty of whether the kinase involved in the catabolic pathway would be able to phosphorylate the substrates. By quantifying residual ATP, the high specificity of N-acetyl-D-glucosamine kinase could be verified. This result led us to think about the design of an organic synthesis strategy that would allow the phosphorylation of glucosamine in carbon 6. A simple synthetic route was designed based on the protection of the two most reactive moieties of the amino sugars and the reactivity of the hydroxy group on carbon 6. However, we had problems with the purification step of the final product due to its high polarity. The next stage of this investigation was to confirm the transformation of GlcNAc into ManNAc. For this, an NMR analysis was designed that would detect the presence of both sugars in the reaction system. The epimerization of ManNAc to GlcNAc was detected successfully. Notwithstanding, the reverse reaction could not be detected. Based on the results obtained in the previous stage, we realized that an error was made in the epimerization reaction since we placed the wrong kinase because we did not take into account its substrate specificity. Finally, we tried to produce sialic acid analogs in a fermentative system using different genetic variants of Escherichia coli. Two of the expected analogs, Neu5Pr and Neu5nBu, were obtained. In addition, NagA activity towards substrates with small acyl groups was confirmed.

Master of Science / Department of Geology / Allen W. Archer / Abstract This study compares the tidally influenced facies found within the Tonganoxie Sandstone Member (Stranger Formation, Douglas Group) (Upper Pennsylvanian) of northeastern Kansas with similar facies directly observed in the upper intertidal mudflats of Turnagain Arm of Cook Inlet (Alaska, USA). The two settings contain strikingly similar facies that are characteristic of upper macrotidal estuaries with a strong influence of tidal activities. Identical aspects and features found within both settings include rhythmic vertical variation in stratum thicknesses (cyclic tidal rhythmites), high estimated sedimentation and aggradation rates, and biogenic and physical sedimentary structures (e.g., drag marks, raindrop impressions, arthropod traces and tetrapod trackways, zigzag burrows, runoff washouts, and upright trees, among others). Tidal rhythmites are the most important evidence that is indicative of the tidal influence on the depositional processes of these two study areas. Such cyclic tidal rhythmites have been reported and described from several Carboniferous settings in the eastern USA. Modern analogs to these Carboniferous rhythmites are usually found within upper macrotidal estuarine depositional environments, especially within fluvio-estuarine transitional zones. These environments are distributed over a wide range of modern latitudes. Using cyclic tidal rhythmites as modern analogs for interpreting similar ancient facies is a powerful tool for paleogeographic and paleoenvironmental reconstructions, although it is somewhat a new approach.

In English The thesis deals with research of novel antimicrobial peptides (AMP) Halictines (HAL-1, GMWSKILGHLIR-NH2 a HAL-2, GKWMSLLKHILK-NH2) and their structural analogs isolated from the venom of the wild bee Halictus sexcinctus. The structure and antimicrobial activity of these peptides had been described earlier [1]. The goal of this diploma thesis is to find peptide which is strongly toxic only for cancer cells and nontoxic for normal cells. Using of the fluorescent marked peptides we aimed to acquire the information about mechanism of action of the studied peptides on the cells. Using the MTT test (determination of valuation IC50), the toxicity of HAL-1 and HAL-2 and their analogs against 2 normal cell lines (Human umbilical vein endothelial cells, HUVEC, and normal rat intestinal cells, IEC) and against 2 cancer cell lines (cancer cells of suppository uterine, HeLa-S3 and cancer cells of human colorectal carcinoma, CRC SW 480) was determined. First we tested antimicrobial peptides with antimicrobial activity and low hemolytic activity. For verification the toxicity of less active analogs was also determined. We found out that the HeLa-S3 cells are the most sensitive to these peptides. The most toxic peptides (HAL-1/9, HAL-1/18, HAL-2/2) kill 50% of cells in the concentration 2,5 - 10 µM. To obtain...

O hormônio tireoideano (T3) desempenha papel importante no desenvolvimento, no crescimento e no metabolismo celular. Um dos seus principais efeitos é a ativação do metabolismo basal, contribuindo de forma importante com a regulação do peso corporal, enquanto diminui os níveis plasmáticos de triglicérides e colesterol. A ativação seletiva do receptor <font face=\"Symbol\">&#946 para o hormônio tireoideano (TR) por meio de agonistas seletivos reduziu níveis séricos de colesterol além de aumentar o metabolismo sem causar efeitos indesejáveis sobre o coração, osso ou músculo esquelético. Estes dados sugerem que estes agonistas poderiam ser úteis no tratamento das manifestações da síndrome metabólica tais como obesidade, hipercolesterolemia e resistência à insulina. Dessa forma, estudamos os efeitos da ativação do TR usando um agonista também da série GC, o GC-24, em ratos machos Wistar tratados com dieta rica em gordura e submetidos a injeções diárias de T3 correspondente a 10x a dose fisiológica (30g/g P.C./dia) ou GC-24 em dose equimolar (17g/g P.C./dia). Nosso estudo mostrou que o GC-24 preveniu algumas alterações metabólicas típicas da síndrome metabólica, tais como o aumento da massa gorda, intolerância à glicose e hipertrigliceridemia e corrigiu parcialmente outras como a hipercolesterolemia, o aumento do conteúdo de colesterol hepático e IL-6. Estes achados sugerem um papel importante do TR na mediação dos efeitos do T3 e devem ter repercussão importante na utilização potencial de agonistas seletivos ao TR<font face=\"Symbol\">&#946 como agentes hipocolesterolemiantes / Thyroid hormone (T3) plays an important role in the development, growth and cell metabolism. One of its main effects is to activate the basal metabolic rate significantly contributing to the regulation of body weight, while decreasing serum triglycerides and cholesterol levels. Thyroid hormone receptor selective activation through selective agonists reduced serum cholesterol levels besides increasing metabolic rate without causing undesirable side effects on the heart, bone or skeletal muscle. These data suggest that these agonists could be useful in the treatment of metabolic syndrome manifestations such as obesity, hypercholesterolemia and insulin resistance. Thus, we studied the effects of TR activation also using an agonist from the GC series, the GC-24 in male Wistar rats treated with high fat diet and submitted to daily T3 injections, corresponding to 10x physiological dose (30g/g B.W. /day) or equimolar doses of GC-24 (17g/g P.C. /day). Our study has shown that GC-24 prevented some of the metabolic abnormalities typical of metabolic syndrome such as increase in fat mass, glucose intolerance and hypertriglyceridemia and partially corrected other ones like hypercholesterolemia, the increase in hepatic cholesterol and IL-6 levels. These findings suggest that TR has an important role in the mediating of T3 effects and should have important repercussions in the potential use of selective agonists to TR as cholesterol lowering agents.

Diversas classes de compostos orgânicos de telúrio foram exploradas neste trabalho. Inicialmente foi estudada a transmetalação entre teluretos alílicos e dibutil cianocupratos de lítio de ordem superior, levando aos respectivos cianocupratos alílicos de lítio. Estes, por sua vez, foram acoplados com triflatos vinílicos, importantes intermediários sintéticos preparados previamente a partir de teluretos vinílicos, levando a sistemas altamente insaturados em ótimos rendimentos (Esquema 1). (Ver no arquivo em PDF) Em seguida, foi explorada a reatividade de teluretos aromáticos frente a reagentes organometálicos. Cianocupratos arílicos, gerados a partir da transmetalação entre teluretos aromáticos com cianocupratos de lítio de ordem superior, foram adicionados a cetonas &#945;,&#946; -insaturadas, levando aos produtos de adição 1,4 em bons rendimentos (Esquema 2). (Ver no arquivo em PDF) Teluretos vinílicos funcionalizados de configuração Z também foram alvo de estudo visando a formação de ligação carbono-carbono. Reações de substituição entre estes teluretos e cianocupratos de lítio de ordem inferior levaram a cetonas e ésteres &#945;,&#946;- insaturados com estereoquímica defInida em ótimos rendimentos (Esquema 3). (Ver no arquivo em PDF) De agosto/20OJ a março/2004, a aluna realizou um estágio sanduíche na University of California, Santa Barbara, sob a orientação do Prof. Bruce H. Lipshutz, onde realizou estudos sobre a ciclização de Bergman, visando a síntese do fragmentobiarílico A-B da vancornicina. Diversas condições para a ciclização foram estudadas com um composto modelo (Esquema 4) (Ver no arquivo em PDF) e parte da síntese total do fragmento da vancomlcma, onde a ciclização seria a etapa-chave, foi realizada com sucesso (Esquema 5). (Ver no arquivo em PDF) / Several classes of organotellurium compounds were explored in this work. First, transmetallation reaction between allylic tellurides and higher order dilithium dibutyl cyanocuprates was carried out, leading to the corresponding allylic cyanocuprates. Then these reagents performed cross-coupling reactions with vinylic triflates, important synthetic intermediates prepared previously from vinylic tellurides, affording highly unsaturated systems in high yields (Scheme 1). (See in file PDF) Next, the reactivity of aryl tellurides was explored with some organometallic reagents. Aryl cyanocuprates, generated by transmetallation reaction between aryl tellurides and higher order lithium cyanocuprates, were reacted with &#945;,&$946;-unsaturated ketones, yielding 1,4-addition products (Scheme 2). (See in file PDF) Functionalized Z-vinylic tellurides were also investigated in reactions aiming carbon-carbon bond formation. Substitution reactions of these tellurides with lower order lithium cyanocuprates gave &#945;,&#946;-unsaturated ketones and esters with defined stereochemistry in good yields (Scheme 3). From Aug/03 to Mar/04, the student worked in the University of California, Santa Barbara, under the supervision of Prof. Bruce H. Lipshutz, where studies concerning the Bergman cyclization were performed, aiming the synthesis of the vancomycin A-B biaryl fragment. Several conditions for this cyclization were investigated using a model compound (Scheme 4) (See in file PDF) and part of the total synthesis of the vancomycin fragment, in which the Bergman cyclization would be the key-step, was accomplished (Scheme 5). (See in file PDF)