A compreensão dos fenômenos de adsorção e difusão em superfícies é fundamental no desenvolvimento de materiais de alto rendimento utilizados em uma série de processos de grande relevância industrial. A modelagem de materiais adsorventes porosos através de modelos de rede tem seu potencial uma vez que se pode estudar os fenômenos a nível microscópico incorporando uma série de parâmetros estatísticos importantes na compreensão dos mecanismos nessa escala. Neste trabalho de dissertação de mestrado, em um primeiro momento, foram utilizadas redes bidimensionais quadradas com abordagem de percolação de sítio-sítio para modelar superfícies sujeitas às condições de adsorção em tempo infinito, com o intuito de se estudar as isotermas de adsorção em processos batelada. Numa primeira parte foi observada uma relação estatística na determinação das isotermas de adsorção, em que a probabilidade de adsorção estava condicionada ao número de moléculas na fase líquida. Na segunda parte foram incorporados diferentes tipos e tamanhos de moléculas, sendo observados diferentes comportamentos das isotermas de adsorção de acordo com a variação dessas moléculas adsorvidas. Outro fenômeno de interesse foi o estudo do Limiar de Percolação utilizando diferentes tipos e tamanhos de moléculas, sendo observados comportamentos específicos para cada caso. Desta forma, pode-se obter parâmetros das isotermas relacionados com os tipos e tamanhos moleculares estudados, sendo observado uma forte dependência daqueles com o tamanho da molécula, uma vez que a seletividade à adsorção aumenta com o tamanho da molécula. Ainda nesta primeira parte foram calculados também a probabilidade de ocupação relacionada com a entropia, observando comportamentos na probabilidade de ocupação a cada etapa de tempo. Em um segundo momento, foi estudado a dinâmica de difusão, mediante random walk ou passeadores aleatórios, em redes quadradas e cúbicas, em que foram obtidas leis de potência para cada dimensão. Aspectos como dispersão axial e porosidade foram incorporadas nas simulações, sendo abservados comportamentos específicos para cada caso.

The search for alternatives to the fossil oil and concern about environmental pollution has increasingly supported the importance of biofuels. The production of bio-oil from aquatic plants (water hyacinth) has become as interesting alternative due to its rapid growth rate, robust nature and unrelated to the food chain. The present work aimed to study the application of conventional and catalytic pyrolysis to convert aquatic plants like Eichhornia crassipes (EC) and Eichhornia azurea (EA) in bio-oil, employing Ferrierite and Y zeolite as catalysts. These plants were obtained in Aracaju-SE and Itabaiana-SE, respectively. The micropyrolys is were performed at three temperatures (400, 500 and 600 °C). The catalytic micropyrolysis using Ferrierite and Y zeolite was performed in the same condition applying 1 and 5% of catalysts w/w. The bio-oils solutions obtained were characterized by GC/MS and GC-FID. The micropyrolysis performed in the absence of catalyst showed similar chromatographic profiles to the biomasses tested, with the composition of bio-oils showing phenolic compounds, acids and alcohols. With Ferrierite as catalyst at 5% in the micropyrolysis and performing a study from the total area of the obtained chromatograms was observed the higher yield by GC-FID caused by the increased formation of small molecular mass compounds from biomasses. However, when used 1% of the same catalyst to EC was not observed a very significant difference in relation with no catalyst pyrolysis. To the EA in this condition was observed a significant yield reduction when performed at 500 °C. When used Y catalyst for EA pyrolysis a smaller yield was observed at all studied temperatures that shows a significantly inhibited formation of compounds derived from these lignocelullosic biomasses. However for the EC catalytic pyrolysis with 5% of Y catalyst at 500 °C we observed the largest decrease in the yield from the chromatograms area. The bio-oils characterization gave compounds identified belong to the following classes: alcohol, phenol, and sugar acids. The bio-oils from catalytic pyrolysis of EC and EA biomass showed a high content of phenolic compounds and acidic compounds. / A procura por soluções alternativas para a substituição total ou parcial do petróleo e a preocupação com a poluição ambiental tem reforçado cada vez mais a importância da produção de biocombustíveis. Neste sentido a produção de bio-óleo a partir de plantas aquáticas tornou-se uma alternativa interessante. Estas plantas são invasoras e possuem alta taxa de crescimento, natureza robusta e não tem relação com a cadeia alimentar. Neste trabalho, biomassas provenientes de plantas aquáticas, obtidas em Itabaiana-SE e Aracaju-SE, das espécies crassipes (EC) e azurea (EA), ambas do gênero Eichhornia, foram submetidas a micropirólise convencional a três temperaturas, 400, 500 e 600 ºC, e catalítica empregando catalisadores do tipo zeólita Ferrierita e Y nas proporções de 1 e 5%. As soluções de bio-óleos produzidas foram caracterizadas por CG/EM e CG-FID. Na micropirólise realizada na ausência de catalisador foi observado semelhança na composição química do bio-óleo para todas as condições testadas. Empregando 5% de catalisador Ferrierita na micropirólise, e realizando um estudo da área total dos cromatogramas obtidos foram observados aumentos significativos a 400 ºC para EC (+53,74%) e para a EA (+43,67%). A 1% deste mesmo catalisador para a EC houve diminuição da área total nas três temperaturas, enquanto que para EA houve diminuição na área total a 500 ºC (-48,09%). Quando empregado a zeólita Y nas duas proporções foi observado menor capacidade de produção de bio-óleo para EA em todas as temperaturas estudadas. A maior diminuição de área foi a 600 ºC (-25,70%) a 1% de catalisador e quando utilizado 5% foi a 500 ºC (-84,34%), ou seja, houve a inibição significativa na formação de bio-óleo. Para a EC foi observado a maior diminuição da capacidade de conversão térmica catalítica desta biomassa em bio-óleo na condição de 5% de zeólita Y, a 500 ºC (-33,23%) e na condição de 1% de zeólita Y, a 600 ºC (-46,77%). Os principais compostos identificados nos bio-óleos obtidos foram das classes do álcoois, fenóis, ácidos e açúcares. O bio-óleo obtido por pirólise catalítica das biomassas EC e EA apresentou um alto teor de compostos fenólicos e ácidos.

The present thesis work is dedicated to the implementation of novel electrochemical methods for the assay of drug compounds such as paracetamol and ascorbic acid and biologically relevant biothiols such as cysteine and glutathione. Particular attention has been paid to the development and application of amperometric detectors allowing for a readily surface renewing and for highly selective and sensitive assays.<p>Coupling of a screen printed electrochemical detector with a monolithic chromatographic column was performed for high-throughput analysis along with selectivity, sensitivity and good precision. The modification of a glassy carbon electrode with a perm-selective membrane was investigated in order to provide an electrochemical sensor for on-site analysis. Acetaminophen was investigated as a model drug compound because of its extensive use in drug “pain killer” medication.<p>Along with the aims of this thesis, a silver polycrystalline electrode was investigated as a sensitive and class selective electrode for the assay of small thiol-based molecules. The silver electrode was implemented for the first time as an amperometric detector coupled to liquid chromatography for the assay of thiols. Application to the study of thiol species present in white wines was realized in order to illustrate the potential of the silver working electrode as amperometric detector. / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

<p>Steroidna jedinjenja spadaju u grupu supstanci sa &scaron;irokim spektrom biolo&scaron;kog delovanja i predstavljaju dobru polaznu osnovu za sintezu mnogih derivata sa željenim biolo&scaron;kim potencijalom. Organskim sintezama se do&scaron;lo do velikog broja steroidnih derivata, od kojih su neki pokazali značajnu biolo&scaron;ku aktivnost, kao &scaron;to je citotoksičnost prema različitim ćelijskim linijama kancera. Karakterizacija novosintetisanih jedinjenja može se izvesti eksperimentalnim i računarskim (in silico) metodama. U ovoj doktorskoj disertaciji predstavljeno je eksperimentalno određivanje lipofilnosti 17&alpha;-pikolil i 17(E)-pikoliniliden androstanskih derivata primenom visokopritisne tečne hromatografije na obrnutim fazama, a potom hemometrijska analiza hromatografskog pona&scaron;anja (hromatografske lipofilnosti) QSRR pristupom. Hemijska struktura analiziranih derivata opisana je numerički, pomoću izračunatih molekulskih deskriptora. U drugom delu doktorske disertacija predstavljena je QSAR analiza citotoksične aktivnosti 17&alpha;-pikolil i 17(E)-pikoliniliden androstanskih derivata prema ćelijama androgen-receptor negativnog kancera prostate (AR-neg. PC-3). Odabir najkvalitetnijih QSRR i QSAR modela obavljen je na osnovu izračunatih statističkih parametara, a njihovo rangiranje izvedeno je primenom metode sume razlika rangova (SRD). Pored regresionih QSRR i QSAR hemometrijskih metoda, primenjene su i klaster analiza i analiza glavnih komponenata sa ciljem utvrđivanja sličnosti ili razlika između analiziranih derivata na<br />osnovu izračunatih molekulskih deskriptora.</p> / <p>Steroidal compounds belong to the group of substances with wide spectrum of biological activity and represent the basic material for synthesis of many derivatives<br />with preferred biological potential. A grate number of steroidal derivatives have been<br />obtained through organic syntheses, many of which have demonstrated significant<br />biological activity, such as cytotoxicity toward various cancer cell lines. Characterization of newly synthesized compounds can be achieved experimentally<br />and by computational approach (in silico). This doctoral dissertation describes<br />experimental determination of lipophilicity of 17&alpha;-picolyl and 17(E)-picolinylidene<br />androstane derivatives applying reversed-phase high pressure liquid chromatography followed by quantitative structure-retention relationship (QSRR)<br />chemometric analysis of chromatographic behaviour (chromatographic lipophilicity).<br />Chemical structure of the analyzed derivatives was described numerically by in silico<br />molecular descriptors. The second part of this dissertation describes quantitative<br />structure-activity relationship (QSAR) analysis of cytotoxic activity of 17&alpha;-picolyl and<br />17(E)-picolinylidene androstane derivatives toward androgen-receptor negative<br />prostate cancer cell line (AR-neg. PC-3). Selection of the best QSRR and QSAR<br />models was carried out based on their statistical parameters, and their ranking was<br />done by sum of ranking differences (SRD) method. Besides the regression QSRR and QSAR chemometric methods, cluster analysis and principal components analysis were conducted in order to reveal possible similarities and dissimilarities among the studied derivatives on the basis of calculated molecular descriptors.</p>

No / Shallow oval bowls used on the Baltic coast in the Mesolithic have been suggested as oil lamps, burning animal fat. Here researchers confirm the use of four coastal examples as lamps burning blubber-the fat of marine animals, while an inland example burned fat from terrestrial mammals or freshwater aquatics-perhaps eels. The authors use a combination of lipid biomarker and bulk and single-compound carbon isotope analysis to indicate the origin of the residues in these vessels.

High Performance Liquid Chromatography (HPLC) is a widely used tech-nique both for detecting and purifying substances in academy and in the industry. In order to facilitate the use of, and knowledge in HPLC, character-ization of stationary phases is of utmost importance. Tailor made characteri-zation methods and workflows are steadily increasing the speed and accura-cy in which new separation systems and methods are developed. In the field fundamental separation science and of preparative chromatography there is always the need for faster and more accurate methods of adsorption isotherm determination. Some of that demand are met with the steadily increase of computational power, but the practical aspects on models and methods must also be further developed. These nonlinear characterization methods will not only give models capable of describing the adsorption isotherm but also actual values of local adsorption energies and monolayer saturation capacity of an individual interaction sites etc.The studies presented in this thesis use modern alkali stable stationary phas-es as a model phase, which will give an insight in hybrid materials and their separation mechanism. This thesis will include an update and expansion in using the Elution by Characteristic Points (ECP) method for determination of adsorption isotherms. The precision is even further increased due to the ability to use slope data as well as an increase in usability by assigning a set of guidance rules to be applied when determine adsorption isotherms having inflection points. This thesis will further provide the reader with information about stationary phase characterization and the power of using existing tech-niques; combine them with each other, and also what the expansion of meth-ods can revile in terms of precision and increased usability. A more holistic view of what benefits that comes with combining a non-linear characteriza-tion of a stationary phase with more common linear characterization meth-ods are presented.