Matrix-assisted laser desorption/ionization (MALDI) has been celebrated as a soft ionization method for analyzing very diverse biological species including large proteins, peptides, carbohydrates, lipids and metabolites. The fact that MALDI is tolerant to salts and buffers and that it mostly produces singly charged ions from intact biomolecules is considered highly advantageous over electrospray ionization (ESI). Almost two decades after the introduction of vacuum MALDI, the technique was successfully implemented under atmospheric pressure (AP) conditions by Laiko and co-workers. Some of the most salient advantages of AP-MALDI over vacuum MALDI are its ability to generate intact ions from labile species with minimal fragmentation due to collisional cooling under AP, the ability of performing MSn experiments, and its exchangeability with other ion sources. However, AP-MALDI suffers from limited sensitivity due to low ion transmission efficiency under AP conditions. Because sensitivity is a function of the sample pretreatment method of choice, both preconcentration and selective sample fractionation can be used during the initial stages of the analytical pipeline to improve detectability. To that end, the first part of the work presented in this thesis is aimed at investigating various approaches to improve the sensitivity of AP-MALDI for mass spectrometric analysis of biomolecules. Chapter 1 reviews the history of laser desorption ionization (LDI), presenting salient features of vacuum MALDI and AP-MALDI, and concludes with a brief overview of leading ambient ionization techniques, such as Direct Analysis in Real Time (DART) ionization. Chapter 2 presents an investigation of an on chip sample preconcentration approach coupled to AP-MALDI for high-sensitivity analysis of neuropeptides extracted from Aedes aegypti mosquito heads. The theme of exploring efficient and reproducible purification methods for complex biosamples is continued in Chapter 3, where an evaluation of new on-tip solid-phase extraction (SPE) micro columns with various functional groups is presented. A second approach for enhancing AP-MALDI sensitivity by constructing a new pneumatically-assisted (PA) AP-MALDI ion source is presented in Chapter 4, where various factors affecting the performance of this device are investigated. Chapter 5 describes work involving the evaluation of DART ionization as a high-throughput method for the detection and identification of small terpene molecules central to the Aedes aegypti mosquito lifecycle.

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[pt] Diversos trabalhos de pesquisa constatam as evidentes correlações entre a exposição excessiva à radiação solar e a incidência de câncer de pele, de catarata e de envelhecimento precoce da pele. O mercado de cosméticos destinados à proteção solar encontra-se em franca expansão; diversos países adotam legislações específicas para esses produtos. No Brasil eles são regulados pela Agência Nacional de Vigilância Sanitária (ANVISA). Porém, não existem métodos oficiais de análise química para determinar filtros solares em cosméticos. No presente trabalho foi desenvolvido um procedimento de análise qualitativa de cosméticos comerciais com filtros solares por espectrometria de massa LDI-TOF (Laser Desorption Ionization - Time-of-Flight). A técnica LDI utiliza um feixe de luz laser monocromático, Lambda = 337nm, como sonda para excitar, dessorver e ionizar o analito. Embora o espectro da radiação solar seja contínuo, o comprimento de onda utilizado em LDI se situa bem próximo do valor médio da faixa de radiação que compreende UVA e UVB, o que torna a técnica LDI potencialmente apropriada para excitar moléculas das substâncias ativas similarmente aos raios solares. Por tais características, é razoável esperar que LDI seja seletiva para detectar filtros solar presentes nas composições dos cosméticos. Paralelamente, foi utilizada também a espectrometria de massa (252)Cf-PDMS (Plasma Desorption Mass Spectrometry), que utiliza os fragmentos de fissão do nuclídeo radioativo califórnio 252 no lugar do laser. Foram obtidos espectros de massa de íons positivos e negativos de 8 cosméticos comerciais por ambas as técnicas, bem como espectros PDMS das substâncias ativas permitidas pela ANVISA. As massas observadas nos espectros de massa LDI dos produtos selecionados foram comparadas com: i) as massas moleculares de todas as substâncias ativas permitidas; ii) as massas observadas nos espectros PDMS das substâncias padrões permitidas e dos cosméticos comerciais; iii) as massas moleculares dos filtros solares indicados nos rótulos. A seletividade da técnica LDI para identificar filtros solares em cosméticos foi demonstrada pelos espectros de massa de íons positivos e negativos das oito amostras analisadas. / [en] Several studies of research note the obvious correlation between excessive exposure to sunlight, and the incidence of skin cancer, cataracts and premature aging of the skin. The market for cosmetics for sun protection is in the booming; various countries adopt laws specific to these products. In Brazil they are regulated by the National Sanitary Surveillance Agency (ANVISA). However, there are no official methods of chemical analysis to determine solar filters in cosmetics. In this work was developed a procedure for qualitative analysis of commercial cosmetics with solar filters by mass spectrometry LDI-TOF (Laser Desorption Ionization - Time-of-Flight). LDI technique uses a beam of monochromatic laser light, Lambda = 337 nm, as a probe to excite, desorbs and ionize the analyte. Although the spectrum of solar radiation is continuous, the wavelength used in LDI is well on the average range of radiation that includes UVA and UVB, which makes technical LDI potentially suitable to excite molecules of active substances similarly to lightning Sun. For such characteristics, it is reasonable to expect that LDI be selective to detect solar filters presents on cosmetics products. In parallel, was also used mass spectrometry (252)Cf-PDMS (Plasma Desorption Mass Spectrometry), which uses fragments of the fission of radioactive nuclide californium 252 instead of laser. Mass spectra were obtained from positive and negative ions, eight commercial cosmetics by both techniques, and PDMS spectra of active substances allowed by ANVISA. Masses observed on LDI mass spectra from selected products were compared with: i) molecular masses of all active substances allowed; ii) masses observed on PDMS mass spectra from standards allowed and commercial cosmetics; iii) molecular masses of sunscreens in its labels. The selectivity of the LDI technique to identify solar filters in cosmetics was demonstrated by mass spectra of positive and negative ions of the eight samples.

Made available in DSpace on 2016-12-23T14:41:52Z (GMT). No. of bitstreams: 1 Thieres Magaive Costa Pereira.pdf: 7173330 bytes, checksum: 5a2aee56b5048351ab0fc838877f8030 (MD5) Previous issue date: 2013-08-23 / O petróleo é uma mistura complexa, sendo uma das misturas mais desafiadoras para as análises químicas. Muitas técnicas são empregadas para a caracterização dos constituintes do óleo. Entretanto, quando combinamos o altíssimo poder de resolução e exatidão da espectrometria de massas, em especial a Ressonância Ciclotrônica de Íons com Transformada de Fourier, (FT-ICR MS) com fontes de ionização a pressão atmosférica, uma atribuição precisa de mais de 20 000 compostos orgânicos do petróleo pode ser obtida. Na indústria do petróleo existe um grande interesse na análise de ácidos naftênicos e asfaltenos devido a problemas como corrosão e formação de depósitos, que aumentam os custos de produção. Portanto este trabalho tem como objetivo a avaliação da termodegradação de ácidos naftênicos, além do emprego das fontes de ESI, APCI, APPI, LDI e MALDI para aquisição de novos dados relativos a caracterização de asfaltenos. Dois petróleos foram utilizados nos ensaios de termodegradação, o petróleo A com acidez de 2,38 mg KOH g-1 e o petróleo B com 4,79 mg KOH g-1 os quais foram tratados a 280, 300 e 350 ºC pelo período de 2, 4 e 6 horas. De uma maneira geral, as principais classes identificadas para ambas às amostras foram O2, N e NO2, respectivamente. Uma leve redução do NAT e da abundância relativa referente à classe O2 foram observado em função da temperatura e do tempo de envelhecimento (T = 280 → 300 oC e t = 2 → 6 h), sendo que a temperatura de tratamento térmico a 350 ºC demonstrou-se determinante na remoção de compostos da classe O2. O perfil químico de amostras de asfaltenos brasileiros foi avaliado utilizando-se cinco diferentes métodos de ionização em ambos os modos de ionização: positivo e negativo, depois, a distribuição de peso molecular, distribuição de classe, parcelas típicas de número de carbono contra DBE e diagramas van Krevelen foram obtidos e discutidos. Um comportamento atípico foi observado para a fonte de LDI e MALDI (±) FT-ICR MS. Um amplo perfil, de m/z 500-3000, apresentando espaçamento de 24 Da foi observado, e este corresponde a formas alotrópicas de fulereno, C60. Em geral, os asfaltenos apresentaram um elevada proporção de espécies heteroatómicas como: HC, HC [H], N, N [H], N2O, N2O [H], N2, N2 [H], O, O[H] para o modo (+) e N, N [H], NO, NO [H], NO, NO2[H], N2O, N2O[H] para o modo negativo. Nos diagramas de DBE contra o número de carbono, os asfaltenos mostraram para cada valor de DBE uma pequena amplitude de compostos com respeito à NC, proporcionando assim, imagens que formam uma linha de 45 ° entre os eixos CN e DBE. Isto indica que estes compostos não exibem grandes cadeias de alquílicas, sendo composta principalmente por anéis aromáticos. Em geral os diagramas de van Krevelen mostraram alta proporção de compostos com razão H/C ~0,7, corroborando com a existência de espécies altamente aromáticas / Petroleum is a complex mixture, being one of the most challenging mixtures for chemical analyzes. Many techniques are employed to characterize constituents of the oil. However , when we combine the highest resolving power and accuracy of mass spectrometry , especially Ion Cyclotron Resonance Fourier Transform ( FT - ICR MS ) with sources of atmospheric pressure ionization , an assignment need more than 20 000 organic compounds in the oil can be obtained. In the oil industry there is a great interest in the analysis of asphaltenes and naphthenic acids due to problems such as corrosion and deposit formation, which increases production costs. Therefore this study aims to evaluate the thermodegradation of naphthenic acids, besides the use of sources of ESI, APCI, APPI, MALDI and LDI for the acquisition of new data on the characterization of asphaltenes . Two test oils were used in thermodegradation of the oil with an acidity of 2.38 mg KOH g -1 and Oil B with 4.79 mg KOH g- 1 which were treated at 280 , 300 and 350 ° C for a period of 2 , 4 and 6 hours. Generally, the major classes identified for both samples O2, NO2, and C, respectively. A slight reduction of NAT and relative abundance refers to the class O2 were observed as a function of temperature and aging time (T = 280 → 300 ° C t = 2 → 6 h), and the heat treatment temperature at 350 ° C showed a determinant for the removal of class O2. The chemical asphaltenes Brazilian samples was evaluated using five different methods of ionization in both modes of ionization: positive and negative, then the molecular weight distribution, distribution class, typical plots versus carbon number and DBE van Krevelen diagrams were obtained and discussed. An unusual behavior was observed for the LDI and MALDI source ( ± ) FT - ICR MS . A comprehensive profile of m / z 500-3000, with spacing of 24 Da was observed, and this corresponds to allotropes of fullerene C60. In general, the asphaltenes had an heteroatómicas high proportion of species such as HC , HC [ H] , N, [ H] , N2O N2O [ H] N2, N2 [ M ] O O [ H] to mode (+) and N, [ H ] , NO [ H] , NO , NO2, [ H] , N2O N2O [ H ] for the negative mode . In the diagrams DBE against the carbon number , the asphaltenes shown for each value of DBE composed of a small amplitude with respect to NC, thus providing images that form a line of 45 ° between the axes CN and DBE. This indicates that these compounds do not exhibit large chain alkyl, composed mainly of aromatic rings. In general diagrams van Krevelen showed a high proportion of compounds ratio H / C ~ 0.7, confirming the existence of highly aromatic species

Over the last decades organic light-emitting diodes (OLEDs) and organic solar cells (OSCs) have gained considerable attention as efficient, flexible, lightweight, and potentially low-cost technology for lighting and display applications or as a renewable energy source, respectively. However, achieving long-term stability remains challenging. Revealing and understanding aging processes is therefore of great interest. This work presents fundamental investigations to understand and circumvent organic device degradation. In the first part, single materials used in organic devices were investigated. By tailoring an attenuated total reflection infrared (ATR-IR) spectrometer to the specific needs and subsequent measurements, it is shown that the tris(8-hydroxyquinoline)aluminum (Alq3) molecule, a well known fluorescent green emitter, degrades during air exposure by the formation of carbonyl groups. By using a laser desorption/ionization time of flight mass spectrometer (LDI-TOF-MS) it was shown that a,w-bis-(dicyanovinylen)-sexithiophen (DCV6T-Bu4), a well known small-molecule material which is used as part of the active layer, reacts with oxygen during ultraviolet (UV) irradiation. By using climate boxes and a sun simulator the impact of dry and humid air as well as sunlight on C60, a widely-used acceptor molecule in organic solar cells, was investigated. The breaking of the C60 cage to C58 and C56 and the further reaction of these components with oxygen as well as the dimerization of C58 and C56 molecules were found. The degradation products such as C58O increase with air exposure time but they are independent of the humidity level of the ambient air as well as sunlight irradiation. Subsequent annealing leads to a decrease of the C58O concentration. Many efficient n-dopants are prone to degradation in air, due to the low ionization potentials, thereby limiting the processing conditions. It was found that the air exposure of the highly efficient n-dopant tetrakis(1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinato)ditungsten(II) (W2(hpp)4) leads to oxidation reactions of the molecule to [W(hpp)2 + O] and other degradation products. The decay constant of W2(hpp)4 and the matching mean growth time of the [W(hpp)2 + O] degradation as well as a second very quick degradation of the dopant could be determined. The two decay constants can be explained by the assumption that W2(hpp)4 molecules, which are involved in the charge transfer, do degrade slower due to the fact that the charge transfer leads to a downshift of the energy levels of the W2(hpp)4 molecule. Apart from the properties of the organic materials, other effects such as the impact of different purification systems on the material purity as well as the dependence of material purity on the OLED lifetime has been investigated. No correlations between the purification grade and the amount of impurities were found. OLEDs which contain N,N\'-di(naphthalen-1-yl)-N,N\'-diphenyl-benzidine (alpha-NPD) purified in a vertically interlaced stainless steel sublimation systems shows slightly higher external quantum efficiencies compared to tube-based vacuum sublimation systems. The devices which contain alpha-NPD purified by a sublimation system have an extended lifetime. Finally, the impact of residual gases during device fabrication on OLED lifetime and electrical characteristics was investigated. It was found that water vapor introduces an additional series resistance to the OLED, while the other gases do not influence the electric characteristics. The presence of nitrogen or oxygen impacts the lifetime of the OLEDs by the same amount. Nitrogen is non-reactive, this leads to the conclusion that the influence of nitrogen and oxygen on the OLED lifetime is of non-chemical nature, such as changes in the morphology of the organic layers. Water vapor introduces an additional, even faster degradation process within the first hours of OLED operation. As major sources of device degradation, the dimerization of 4,7-diphenyl-1,10-phenanthroline (BPhen) as well as the complexation reaction of alpha-NPD with a bis(1-phenylisoquinoline)iridium(III) (Ir(piq)2) fragment was identified.

Asset and Liability Management (ALM) models have become well established decision tools for pension funds. ALMs are commonly modelled as multi-stage, in which a large terminal wealth is required, while at intermediate time periods, constraints on the funding ratio, that is, the ratio of assets to liabilities, are imposed. Underfunding occurs when the funding ratio is too low; a target value for funding ratios is pre-specified by the decision maker. The risk of underfunding has been usually modelled by employing established risk measures; this controls one single aspect of the funding ratio distributions. For example, controlling the expected shortfall below the target has limited power in controlling shortfall under worst-case scenarios. We propose ALM models in which the risk of underfunding is modelled based on the concept of Second Order Stochastic Dominance (SSD). This is a criterion of ranking random variables - in our case funding ratios - that takes the entire distributions of interest into account and works under the widely accepted assumptions of decision makers being rational and risk averse. In the proposed SSD models, investment decisions are taken such that the resulting short-term distribution of the funding ratio is non-dominated with respect to SSD, while a constraint is imposed on the expected terminal wealth. This is done by considering progressively larger tails of the funding ratio distribution and considering target levels for them; a target distribution is thus implied. Different target distributions lead to different SSD efficient solutions. Improved distributions of funding ratios may be thus achieved, compared to the existing risk models for ALM. This is the first contribution of this thesis. Interesting results are obtained in the special case when the target distribution is deterministic, specified by one single outcome. In this case, we can obtain equivalent risk minimisation models, with risk defined as expected shortfall or as worst case loss. This represents the second contribution. The third contribution is a framework for scenario generation based on the "Birth, Immigration, Death, Emigration" (BIDE) population model and the Empirical copula; the scenarios are used to evaluate the proposed models and their special cases both in-sample and out-of-sample. As an application, we consider the planning problem of a large DB pension fund in Saudi Arabia.

The foci of this dissertation are on advanced liquid chromatography (LC) separation and mass spectrometry (MS) techniques for the analysis of small bioactive molecules. In addition to discussing general aspects of such techniques the results from analyses of polyphenols (PPs), alkaloids and amino acids published in five appended studies are presented and discussed. High efficiency and well understood principles make LC the method of choice for separating analytes in many kinds of scientific investigations. Moreover, when LC is coupled to an MS instrument, analytes are separated in two stages: firstly they are separated and pre-concentrated in narrow bands using LC and then separated according to their mass-to-charge (m/z) ratios in the MS instrument. Some MS instruments can provide highly accurate molecular weight measurements and mass resolution allowing identification of unknown compounds based purely on MS data, thus making prior separation unnecessary. However, prior separation is essential for analyzing substances in most complex matrices – especially useful is the ultra-high performance LC (UHPLC). The advantages of using UHPLC rather than HPLC for the analysis of PPs in tea and wine were evaluated in one of the studies this thesis is based upon. The phenolic composition of red wine was also examined, using a novel LDI technique, following solid phase extraction (SPE). A class of small aromatic molecules (medicinally important alkaloids) also proved to be amenable to straightforward analysis, by thin layer chromatography (TLC) work-up followed by LDI-MS. Finally, a LC-MS method for monitoring neurotoxins (β-N-methyl-amino-L-alanine and 2,3-diaminobutyric acid) in complex biological matrices was developed and applied. Overall, the studies show that careful attention to the physicochemical properties of analytes can provide insights that can greatly facilitate the development of alternative methods to analyze them, e.g. by LDI. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: In press. Paper 5: Manuscript.</p>

The process of literacy comprehends the intellectual, social, psychic, and emotional factors of the students, leading them to the experience of reading and writing in social practices. This research, entitled "The process of literacy with elementary school children mediated by the Interactive Whiteboard", is epistemologically established in the field of Education, grounded in the Piagetian and Ferreirian propositions of the psychogenesis of written language mediated by the Interactive Whiteboard (LDI) in the construction of different theoretical knowledge and practical propositions of doing, in the light of the interactionist theory of Vygotsky. In order to delineate a line of reasoning, the following research problem was chosen: how can the Interactive Whiteboard be able to provide literacy practices for primary school children through its use in teaching-learning processes? The general objective of the research is to investigate how the LDI can enable children's literacy practices in primary education 1 through its use in teaching-learning processes. In order to achieve the stated objective, the specific objectives were defined: identify in the pilot education plan of the 2nd year of primary education 1, actions that contribute to the literacy process mediated by the LDI; to verify how the LDI mediation can enhance the literacy process and analyze the application of the activities proposed in the pilot education plan. The theoretical basis was based on the publications that approach the conceptual and practical aspects of the research topic, considering its scope, with emphasis on the references involving Digital Information and Communication Technologies (TDIC); Interactive Whiteboard (LDI); Literacy and Teaching-Learning Process. The methodological approach chosen is the qualitative research, founded on the Bogdan and Biklen (1994) conjectures, based on the Participant Research of Brandão and Streck (2006), grounded on technical procedures, bibliographical, documentary and field study, exploratory and descriptive of Gil (2010). The following instruments were used for the the data collection: questionnaire of Lüdke and André (1986); participant observation of Lakatos and Marconi (2010); field diary of Macedo (2010) and Bogdan and Biklen (1994). The information collected was analyzed through content analysis (BARDIN, 2011), from which emerged four main categories: the cybercultural profile of 2nd year students B; the educational potential of LDI in the literacy of those surveyed; the LDI as a tactic for the development of language structure and cognitive aspects in the acquisition of literacy. The results show that: (a) the students are digital natives (they can be considered digital sages, by Prensk's (2009) observations), they are protagonists in individual or group practical activities and with excellent interaction between them; (b) the use of LDI in the teaching-learning process contributed to the learning and improvement of student literacy; (c) the interactions of the LDI in the applications of the activities allowed the enrichment of the language structure, configuring itself as one more resource to enhance the communication and the cognitive aspects of the students within the pedagogical practice. / O processo de alfabetização compreende os fatores intelectuais, sociais, psíquico, emocional dos estudantes, levando-os à experiência da leitura e da escrita nas práticas sociais. Esta pesquisa intitulada “O processo de alfabetização com crianças do ensino fundamental mediado pela Lousa Digital Interativa”, institui-se, epistemologicamente, no âmbito da Educação, alicerçando-se nas proposições piagetianas e ferreirianas da psicogênese da língua escrita, mediada pela Lousa Digital Interativa (LDI) na construção de diferentes saberes teóricos e proposições práticas de fazeres, à luz da teoria interacionista de Vygotsky. Para delinear uma linha de raciocínio, elegeu-se o seguinte problema de investigação: como a Lousa Digital Interativa pode viabilizar práticas de alfabetização das crianças do ensino fundamental mediante o seu uso nos processos de ensino-aprendizagem? Como objetivo geral da pesquisa tem-se: investigar como a Lousa Digital Interativa (LDI) pode viabilizar práticas de alfabetização das crianças no ensino fundamental 1 mediante o seu uso nos processos de ensino-aprendizagem. A fim de atingir o objetivo posto, definiu- se os objetivos específicos: identificar no plano de ensino piloto do 2º ano do ensino fundamental 1, ações que contribua para o processo de alfabetização mediado pela LDI; verificar como a mediação da LDI pode potencializar o processo de alfabetização e analisar à aplicação das atividades propostas no plano de ensino piloto. A fundamentação teórica norteou-se nas publicações que abordam os aspectos conceituais e práticos da temática da pesquisa, considerando a sua abrangência, com destaque para as referências que envolvem Tecnologias Digitais de Informação e Comunicação (TDIC); Lousa Digital Interativa (LDI); Alfabetização e Processo de Ensino-Aprendizagem. A abordagem metodológica escolhida é a da pesquisa qualitativa, fundamentada nas conjecturas de Bogdan e Biklen (1994), baseada na Pesquisa Participante de Brandão e Streck (2006), fundamentada através dos procedimentos técnicos bibliográfico, documental e estudo de campo, de cunho exploratório e descritivo de Gil (2010). Como instrumentos na coleta de dados foram utilizados: questionário de Lüdke e André (1986); observação participante de Lakatos e Marconi (2010); diário de campo de Macedo (2010) e Bogdan e Biklen (1994). As informações coletadas foram analisadas por meio da análise de conteúdo (BARDIN, 2011), da qual emergiram quatro grandes categorias: o perfil cibercultural dos alunos do 2º ano B; o potencial educativo da LDI na alfabetização dos pesquisados; a LDI como tática para o desenvolvimento da estrutura da linguagem e os aspectos cognitivos na aquisição da alfabetização. Os resultados obtidos evidenciam que: (a) os alunos são nativos digitais (podendo ser considerados sábios digitais, pelas observações de Prensky (2009)), são protagonistas em atividades práticas individuais ou em grupo e com excelente interação entre eles; (b) o uso da LDI no processo de ensino-aprendizagem contribuiu para o aprendizado e aprimoramento da alfabetização dos alunos; (c) as interatividades da LDI nas aplicações das atividades permitiram o enriquecimento da estrutura de linguagem, configurando-se como mais um recurso para potencializar a comunicação e os aspectos cognitivos dos alunos dentro da prática pedagógica. / São Cristóvão, SE

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