An accurate model for RO process has significant importance in the simulation and optimization proposes. A steady state model of RO process is developed based on solution diffusion theory to describe the permeation through membrane and thin film approach is used to describe the concentration polarization. The model is validated against the operation data reported in the literature. For the sake of clear understanding of the interaction of feed temperature and salinity on the design and operation of RO based desalination systems, simultaneous optimization of design and operation of RO network is investigated based on two-stage RO superstructure via MINLP approach. Different cases with several feed concentrations and seasonal variation of seawater temperature are presented. Also, the possibility of flexible scheduling in terms of the number of membrane modules required in operation in high and low temperature seasons is investigated A simultaneous modelling and optimization method for RO system including boron removal is then presented. A superstructure of the RO network is developed based on double pass RO network (two-stage seawater pass and one-stage brackish water pass). The MINLP problem based on the superstructure is used to find out an optimal RO network which will minimize the total annualized cost while fulfilling a given boron content limit. The effect of pH on boron rejection is investigated at deferent seawater temperatures. The optimal operation policy of RO system is then studied in this work considering variations in freshwater demand and with changing seawater temperature throughout the day. A storage tank is added to the RO layout to provide additional operational flexibility and to ensure the availability of freshwater at all times. Two optimization problems are solved incorporating two seawater temperature profiles, representing summer and winter seasons. The possibility of flexible scheduling of cleaning and maintenance of membrane modules is investigated. Then, the optimal design and operation of RO process is studied in the presence of membrane fouling and including several operational variations such as variable seawater temperature. The cleaning schedule of single stage RO process is formulated as MINLP problem using spiral wound modules. NNs based correlation has been developed based on the actual fouling data which can be used for estimating the permeability decline factors. The correlation based on actual data to predict the annual seawater temperature profile is also incorporated in the model. The proposed optimization procedure identified simultaneously the optimal maintenance schedule of RO network including its design parameters and operating policy. The steady state model of RO process is used to study the sensitivity of different operating and design parameters on the plant performance. A non-linear optimization problem is formulated to minimize specific energy consumption at fixed product flow rate and quality while optimizing the design and operating parameters. Then the MINLP formulation is used to find the optimal designs of RO layout for brackish water desalination. A variable fouling profile along the membrane stages is introduced to see how the network design and operation of the RO system are to be adjusted Finally, a preliminary control strategy for RO process is developed based on PID control algorithm and a first order transfer function (presented in the Appendix).

Estudos epidemiológicos na Região Amazônica são escassos, principalmente aqueles que fazem diagnósticos do estado nutricional relativo a micronutrientes populações que vivem em comunidades ribeirinhas isoladas. Portanto, este estudo objetivou avaliar o estado nutricional relativo ao zinco de crianças em duas comunidades ribeirinhas da Cidade de Porto Velho RO: Gleba do Rio Preto e Demarcação. Foram avaliadas 39 crianças entre 3 e 9 anos, destas 29 da Demarcação e 10 da Gleba do Rio Preto. O perfil sócio-econômico mostrou que todas as famílias avaliadas não tinham destino adequado para os dejetos, as únicas fontes de água eram os rios ou poços cacimba e a principal fonte de renda era a cultura de subsistência, fornecendo renda mensal inferior a um salário mínimo. A avaliação do consumo alimentar mostrou que 39% das crianças avaliadas tinham ingestão de zinco inferior a EAR, a adequação calorica mostrou que 50% das crianças avaliadas tinham ingestão calórica inferior a 90%, no entanto, 92% das crianças tinham ingestão adequada de proteínas. A avaliação antropométrica, de acordo com o escore Z, mostrou que 92%, 84% e 86% das crianças estavam eutróficas para os padrões Estatura/Idade, Peso/Estatura e Peso/Idade, respectivamente. Na avaliação da concentração de zinco no plasma foi observada uma prevalência de deficiência em 90% dos casos e a concentração do zinco eritrocitário mostrou 71% de deficiência. Assim, pode-se concluir que o estado nutricional relativo ao zinco é grave, visto que a ingestão e as concentrações deste nutriente nos parâmetros avaliados estão reduzidas na maioria da população avaliada. / Epidemiological studies in Amazon Region are rarely, especially those that evaluated micronutrients nutritional status on isolated communities. This study aimed to evaluate zinc nutritional status from children who lives in two riverine communities from Porto Velho City RO; Gleba Rio Preto and Demarcação. We carried out of 39 children (3 to 9 years old). The economical and social profile showed that all families had no appropriate dejections destination, the waters sources were from well and rivers and the main source income were from subsistence culture. The food assessment showed 39% from evaluated children had no adequate zinc intake according EAR, the calorie intake was inadequate on 50% from evaluated children. The anthropometrics evaluation showed, according Z score, 92%, 84 e 86% of children were eutrophics to the standards Height/Age, Weight/Height and Weight/Age, respectively. The assessment of zinc concentrations on serum showed a prevalence of deficiency in 90% of the evaluated cases, and the zinc concentration on erythrocytes showed 71% of deficiency and 21% of normality in the evaluated children. Thus, we can conclude the nutritional status is severe, therefore the zinc intake and zinc concentrations are reduced in majority assessed population.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-03-27T22:34:56Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_DiagnosticoEnteroparasitoresComunidade.pdf: 52709616 bytes, checksum: ece3439cf581744fb07f26fed5d6b1ef (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-04-02T15:40:31Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_DiagnosticoEnteroparasitoresComunidade.pdf: 52709616 bytes, checksum: ece3439cf581744fb07f26fed5d6b1ef (MD5) / Made available in DSpace on 2013-04-02T15:40:32Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_DiagnosticoEnteroparasitoresComunidade.pdf: 52709616 bytes, checksum: ece3439cf581744fb07f26fed5d6b1ef (MD5) Previous issue date: 2002 / As enteroparasitoses estão entre as infecções mais comuns no homem, apresentando-se com maior intensidade em países subdesenvolvidos por estarem diretamente relacionadas às condições higiênico-sanitárias. Este estudo tem por objetivo investigar a presença de enteroparasitas causadoras de doenças no homem, em uma comunidade do Movimento dos Trabalhadores Rurais Sem Terra (MST) no estado de Rondônia. No acampamento Pe. Ezequiel, município de Mirante da Serra, RO, foram utilizados os métodos direto e de sedimentação espontânea em água para detecção e identificação das formas parasitárias de protozoários e helmintos em material fecal de residentes do mesmo e o teste de ELISA (Ensaio imunoenzimático) para detecção de coprantígeno específico, anti-GIAP (proteina de aderência inibidora da galactose), de Entamoea histolytica (Tachlab, Blacksburg, VA, USA). Foram examinadas 313 amostras fecais pelos testes coproscópicos e 186 pelo teste de ELISA. A prevalência encontrada foi de 33,5% sendo a E. histolystica, Giárdia Lamblia e os ancilostomídeos os parasitas patogênicos mais frequentes. Não foram encontradas diferenças significativas entre parasitismo e idade, mas entre agente causador da infecção e sexo houve significância entre E. histolytica e sexo feminino. Não foi possível determinar fator (es) de risco relacionado (s) às infecções. Quanto ao resultado do ELISA, foi detectado um número maior de amébiase intestinal por este método do que por coproscopia. Considerando ser o acampamento uma área rural sem infra-estrutura ideal, o baixo parasitismo encontrado foi surpreendente. Todavia, a estrutura alternativa do local somado à organização social do grupo, consciência comunitária e formação básica em saúde, constitui fatores preponderantes para a aprovação e/ou controle das enteroparasitoses. / The infeccions caused by enteroparasites are very common among the humans and prevalent in the underdeveloped countries because of their close linkage to their sanitary and hygiene conditions. This study aims the investigation about the enteroparasites those cause humans illness, in community in the State of Rondonia, organized by the "Rural Workers Movement Without Land" (MST). At that community, called Pe. Ezequiel located in Mirante da Serra municipality, in RO, the direct and the spontaneous sedimentation in water methods were used for the detection and identification of the parasitic forms of protozoas and helmints in excrement materiais, and the ELlSA's test for the detection of the especific antigen, anti- GIAP (galactose inhibitory adherence's protein) Entamoeba histolytica ( Techlab, Blacksburg, VA, USA). 313 fecal samples were tested by the coproscopical methods and 186 by EUSA's test. The total prevalence was 33,5% and the E. histolytica Giardia lamblia and ancilostomides were the most frequent pathogenic parasites. There were no statistical significances between parasitism and age group, but the relation between E. histolytica and the female group had showed significance. The risk factor(s) was (were) not determined in relation to the founded infections among the studied group. The resulta of ELlSA's test detected a higher number of intestinal amebiasis in comparison to those detected by coproscopical method. Taking into account that the community is rural area without a ideal struture for living, the parasitism found was amazing. However, the basic local struture associated to the group's organization, the communitary conscious and the basic health education are main factors for the prevention and/or control of the parasites infections.

Submitted by Edisangela Bastos (edisangela@ufpa.br) on 2013-04-02T18:36:07Z No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoExposicaoMercurio.pdf: 49790897 bytes, checksum: 7b4ada4b4fac2a5c366a557ef3928fcf (MD5) / Approved for entry into archive by Ana Rosa Silva(arosa@ufpa.br) on 2013-04-03T14:40:19Z (GMT) No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoExposicaoMercurio.pdf: 49790897 bytes, checksum: 7b4ada4b4fac2a5c366a557ef3928fcf (MD5) / Made available in DSpace on 2013-04-03T14:40:19Z (GMT). No. of bitstreams: 2 license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Dissertacao_AvaliacaoExposicaoMercurio.pdf: 49790897 bytes, checksum: 7b4ada4b4fac2a5c366a557ef3928fcf (MD5) Previous issue date: 2002 / Fundação Riomar / Foram estudados 103 binômios mãe-filho nascidos em hospitais da cidade de Porto Velho-RO, durante os meses de novembro/2000 até fevereiro/2001. Foram analisadas amostras de cabelo da mãe e do recém-nascido, sangue materno, placenta e cordão umbilical. As coletas das amostras foram realizadas no momento do parto. Aplicou-se questionário a mãe onde se registrou informações relevantes para o risco de contaminação mercurial e/ou malformações. Os produtos da gestação que apresentaram malformação foram incluídos no estudo. A medida da exposição ao Metilmercúrio foi feita utilizando os biomarcadores coletados e realização de técnicas através do método de espectofotometria de absorção atômica pelo vapor frio. Utilizou-se o fator prático de conversão total em mercúrio que é de 0,90 a 0,92. Após análise e estudo estatístico as principais conclusões foram: o consumo de bebida alcoólica durante a gravidez, dentre outras variáveis, não influenciou no aparecimento de malformações, especialmente os defeitos do tubo neural (DNT) a maioria das malformações encontradas foi DNT (66,6%) que foram significativamente correlacionadas com os níveis de mercúrio total no cabelo do recém-nascido; os níveis de mercúrio total na placenta e no cordão umbilical foram equivalentes. / A hundred and three binomials mother-son bomed in hospitaIs of the city of Porto Velho - RO, during the months of November/2000 up to February/2001. Samples of the mother's hair were analyzed and of the newly born, maternal blood, placenta and umbilical cord. The collections of the samples were accomplished in the moment of the childbirth. A questionnaire was applied to mother where enrolled important information for the risk of contamination mercurial and/or congenital anomaly. The products of the gestation that presented congenital anomaly were included in the study. The measure of the exhibition to the Methylmercury was made using the collected biologic marker and accomplishment of techniques through the method of spectofotometric of atomic absorption for the cold vapor. The practical factor of total conversion was used in mercury that is from 0,90 to 0,92. After analysis and statistical study the main conclusions were: the alcoholic drink consumption during the pregnancy, and other variables, didn't influence in the congenital anomaly apparently, mainly neural tube defects (NTD); most of the found congenital anomaly was NTD (66,6%) that were significant correlated with the levels of total mercury in the hair of the newly born; the levels of total mercury, in the placenta and in the umbilical cord, they were equivalent.

Made available in DSpace on 2015-04-22T22:04:00Z (GMT). No. of bitstreams: 1 thais helena.pdf: 4964645 bytes, checksum: f4fc7f4c906908509cd7f44320f45eca (MD5) Previous issue date: 2013-04-18 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Na análise das relações socioculturais advindas dos mecanismos de ressignificação em torno da intensificação e transformação das elaborações das artesanías em palha de tucumã, primeiramente, este trabalho tece a paisagem onde se dá as redes de sociabilidade das artesãs(ãos) entre seus objetos materiais, culturais e simbólicos. Nesse sentido, abalizando os aspectos ambientais, econômicos e culturais das localidades. A memória coletiva é o principal método investigativo que possibilitou compreender a mobilidade empreendida pelas pessoas das margens do Lago Grande do Curuai ao Rio Arapiuns, remodelando novos agrupamentos societários. Na ampliação dos núcleos principais, entre outros motivos, está associada à satisfação das necessidades individuais de alimentar-se, vestir-se e abrigar-se; reprodução social e econômica. Amparada na memória das artesã(ãos), descrevo a ressignificação desse padrão de teçume local, mediando e mesclando desejos e sentidos às coisas na interpretação dos narradores aos significados que o conjunto cesteiro carrega de vida social. Apoderando-me de uma escrita conjugada entre o campo da pesquisa e o conjunto teórico eleito, considero as transmissões da tradição e a emersão do novo no rompimento de uma realidade social em transição, colocando os objetos culturais rolando na vida das pessoas como mercadorias, mas marcando e resistindo traços culturais. As barreiras que dantes dividiam bruscamente urbano e rural, são agora transpostas, revirando as categorias capitais econômicas e as relações de trocas entre o (pós)moderno (ou pós-industrial?) mundo contemporâneo e agrupamentos societários que ainda mantêm formas distintas de relações econômicas e socioculturais. As análises centraram-se na combinação da realidade da vida das(os) artesãs(ãos) e a condição global, a elaboração e o consumo de bens e objetos. Coisas que demarcam vida, mas, também demarcam territórios.

Reverse osmosis (RO) and ultrafiltration (UF) retentates were ultra-high temperature (UHT) processed and compared for storage life at room temperature. Viscosity studies indicated that UHT-treated, RO retentate delayed age gelation longer than UF retentate at the same total solids level (26% TS). When compared at 6.4% protein level (2x RO vs 2.7x UF where x=ratio of the feed volume to concentrate volume), the storage life for both RO and UF retentates was about 6 to 8 months. Sodium hexametaphosphate (SHMP) and disodium phosphate (DSP) at 1, 3, 5, 10, and 20 mM concentrations were incorporated prior to UHT processing of each sample to improve the shelf life. SHMP at 1 and 3 mM concentrations was effective in delaying age gelation, whereas all levels of DSP accelerated gelation. However, SHMP accelerated age gelation at concentrations of 10 and 20 mM. SHMP at 1 mM in RO retentate was more effective in delaying age gelation than the same SHMP level in two UF samples (22 and 26% TS). Analysis showed that RO/UHT-treated samples had higher soluble calcium and ionic calcium than did UF/UHT-treated samples. The coefficient of determination (R2) was .80 between soluble calcium-to-protein ratio and shelf life.

The design, construction and testing of a reverse-osmosis (PV-RO) desalination system for fresh water shortage area is presented. The system operates from salt water or brackish water and can be embedded in a renewable energy power supply system, since many fresh shortage areas are remote and isolated. Special attention is given to the energy efficiency of small-scale reverse osmosis desalination systems. Limitations of conventional control strategy using toggle control are presented. Based on this, an objective of creating a small-scale reverse osmosis desalination system was set out. Initially, the background information is presented. This includes the natural resources crisis and main desalination technologies and the viability of the integration with renewable energy source. A reverse osmosis (RO) desalination system was assembled and set up at the Curtin University of Technology, Perth, Western Australia Supervisor Control And Data Acquisition (SCADA) system was built using a Human Machine Interface software and a programmable logic controller (PLC). Instrumentation that included signal conditioners was made in analysis of the system characteristics. Initial testing of the system was conducted after the system design and configuration was accomplished. Testing results were used as a guideline for the development of the whole system. / Modelling and simulation of the system components in MATLABSimulink is presented, together with a discussion of the control systems modelling and design procedure, in which the aim was to improve the efficiency of the reverse osmosis system. Simulations show the designed reverse osmosis system with Proportional Integral and Derivative (PID) controller has better performance than other controllers. This consequently leads to a lower overall cost of the water, as well as reducing full maintenance cost of the electric drives in the reverse osmosis unit. Additionally, the configuration of the remote control system through General Package Radio System (GPRS) network is depicted. After the PID control algorithm was programmed into the Programmable Logic Controller (PLC), system experiments were carried out in short durations and long durations. System performance was monitored and experimental results prove that the new control strategy applied increase the water productivity and is able to improve the system efficiency up to 35%. Based on the data obtained from the simulations and experiments, Mundoo Island was chosen to be the location for a case study. The electric load profile of the island was derived from the Island Development Committee in Mundoo. / A water demand profile was created and modelled in Matlab to be the input of the reverse osmosis system. The electric load of the reverse osmosis system was generated from Matlab simulation. This result was entered in Hybrid Optimisation Model for Electric Renewables (HOMER) simulator. Having the designed RO unit as one of the electric loads, the entire remote area power supply (RAPS) system was tested in simulations which shows the energy cost is AUS$0.174 per kWh, lower than the Island Development Committee budget estimation of AUS$0.25 per kWh. The cost of the water treatment is very promising at AUS$0.77 per m3.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 187 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: This dissertation investigates the importance of diffusional and convective fluxes for salts in reverse osmosis (RO) and nanofiltration (NF) membranes. Moreover, the physical and thermodynamic factors controlling the salt permeability are analyzed. The study utilizes direct osmosis (DO) experiments and RO experiments, the later using both flat sheet and spiral wound membrane configurations. The salts considered are chlorides and acetates of alkali metals and alkaline earth metals. The equation governing the salt transport in DO experiments is derived and a phenomenon inverse to concentration polarization in RO is observed. The salt permeability in DO is equal to the salt permeability calculated for the valid cases of the used RO models. DO is suggested as an alternative method in characterizing the salt transport in membranes. The method can be more advantageous than RO due to the lower costs and simplicity of the apparatus. / ABSTRACT: The models used to calculate the salt transport parameters in RO experiments are Spiegler-Kedem model, which considers both diffusion and convection of salt, and Kimura-Sourirajan model, which considers only diffusion of salt. It is found that diffusion is the dominant mechanism of transport in both RO and NF membranes. The percentage of the salt diffusional flux of the total flux is highest for seawater membranes and it is approximately equal for brackish water and nanofiltration membranes. The salt diffusive flux contribute more to the total flux for the 1:2 salts than for 1:1 salts. The two RO models are found equivalent in determining the salt permeability for only the seawater membranes. The Kimura-Sourirajan model overestimates the salt permeability coefficient for salts with rejection coefficient lower than 86%. / ABSTRACT: The permeation rates for studied salts follow the lyotropic series regardless the membrane type (RO or NF), the membrane configuration (flat sheet or spiral wound), the process (DO or RO), or the models used for the calculations. This order of salt permeability is explained by the hydration of the cations, which is quantified by the enthalpy and entropy of hydration. The relative free energy theory can also be used to predict the salt permeability in a membrane based on preliminary data. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Water and energy crises have forced researchers to seek alternative water and energy sources. Seawater desalination can contribute towards meeting the increasing demand for fresh water using alternative energy sources like low-grade heat. Industrial waste heat, geothermal, solar thermal, could help to ease the energy crisis. Unfortunately, the efficiency of the conventional power cycle becomes uneconomically low with low-grade heat sources, while, at the same time, seawater desalination requires more energy than a conventional water treatment process. However, heat discarded from low-grade heat power cycles could be used as part of desalination energy sources with seawater being used as coolant for the power cycles. Therefore a study of desalination using low-grade heat is of great significance. This research has comprehensively reviewed the current literature and proposes two systems that use low-grade heat for desalination applications or even desalination/power cogeneration. The proposed two cogeneration systems are a supercritical Rankine cycle-type coupled with a reverse osmosis (RO) membrane desalination process, and a power cycle with an ejector coupled with a multi-effect distillation desalination system. The first configuration provides the advantages of making full use of heat sources and is suitable for hybrid systems. The second system has several advantages, such as handling highly concentrated brine without external electricity input as well as the potential of water/power cogeneration when it is not used to treat concentrated brine. Compared to different stand-alone power cycles, the proposed systems could use seawater as coolant to reject low-grade heat from the power cycle to reduce thermal pollution.

L???acquisition rapide de r??sistance aux antibiotiques par Staphylococcus aureus force le milieu hospitalier dans ses derniers retranchements au niveau des traitements antibact??riens. Afin de pallier ?? ce probl??me, il est important de continuer ?? innover dans le d??veloppement de compos??s antibiotiques poss??dant des m??canismes d???action novateurs. Le groupe de Fran??ois Malouin a r??cemment d??montr?? que la tomatidine poss??de une activit?? antibact??rienne et antivirulence contre diff??rentes souches de Staphylococcus aureus, ainsi qu???un potentiel synergique avec les antibiotiques de la famille des aminoglycosides. La cible biologique et le m??canisme d???action de la tomatidine ??tant ?? ce jour inconnus, nous avons synth??tis?? une librairie de 34 analogues dans le but de comprendre la relation structure-activit?? de ce compos?? contre les souches persistantes de Staphylococcus aureus, ainsi que dans le but d???am??liorer son activit?? biologique et mieux comprendre son m??canisme d???action. En nous basant sur l???hypoth??se que le squelette st??ro??dien standard servait principalement de support pour orienter les groupements pharmacophores, nous avons concentr?? les modifications chimiques sur les pharmacophores eux-m??mes, soit ?? la fonction hydroxyle en position 3 du cycle A, mais aussi ?? la fonction spiroaminoc??tale constituant les cycles E et F de la tomatidine. Les modifications de l???hydroxyle ont ??t?? effectu??es ?? partir de la tomatidine elle-m??me. Nous avons test?? l???effet de l???inversion de configuration, de l???allylation, de l???oxydation et de la substitution par diff??rentes amines en cette position. Les modifications sur la fonction spiroaminoc??tale ont ??t?? synth??tis??es ?? partir de la tomatidine elle-m??me, mais ??galement ?? partir de l???ac??tate de pr??gn??nolone, un pr??curseur largement utilis?? en chimie st??ro??dienne. Dans le premier cas, les modifications ont consist?? ?? synth??tiser des analogues de la fonction spiroaminoc??tale bloqu??e en conformation ferm??e, ouverte ou partiellement ouverte. Dans le second cas, les modifications ont port?? sur la synth??se d???analogue de la forme ouverte de la fonction spiroaminoc??tale. Tous les produits synth??tis??s ont ??t?? envoy??s au laboratoire du Pr Fran??ois Malouin afin d?????tre test??s pour leur activit?? biologique. Les compos??s ont ??t?? test??s afin de quantifier leur activit?? biologique contre S. aureus, seul ou en synergie avec la gentamicine, et ??galement pour quantifier leur activit?? biologique contre les variantes de petite colonie de S. aureus, un ph??notype bact??rien souvent associ?? ?? des infections r??currentes et difficiles ?? traiter. Ces tests ont ??t?? effectu??s par Isabelle Guay, ??tudiante ?? la ma??trise en biologie ?? l???Universit?? de Sherbrooke. Cette ??tude a men?? ?? l?????tablissement des fondements de la relation structure-activit?? de la tomatidine envers S. aureus, ainsi qu????? la d??couverte de certains compos??s pr??sentant une activit?? biologique am??lior??e. Ce travail a permis la r??daction d???un article scientifique intitul?? ?? Unraveling the structure-activity relationship of tomatidine, a steroid alkaloid with unique antibiotic properties against persistent forms of Staphylococcus ??, soumis ?? European Journal of Medicinal Chemistry en juillet 2013, qui est pr??sent?? en ce m??moire.