Universiẗat, Diss.--Karlsruhe, 2003.

This qualitative text analysis has studied medias portrayal of Taimour Abdulwahab, Anders Behring Breivik and their respective terrorist attacks. The purpose of the essay was to study the newspapers portrayal of the terrorists, with one terrorist being part of an us group and the other one part of a them group. It also aspires to uncover whether the medias portrayal of the terrorists reproduce mechanisms which help sustain the gap between us and them. To answer the essays research questions we have used the media theory about agenda setting and the sociologists Norbert Elias’ and John L. Scotsons theory about established and outsiders. The analysis of news articles the first two days after the terrorist attacks in Swedish newspapers Expressen and Aftonbladet showed a difference in the portrayal of the established Breivik, whos persona and actions were explained on an individual level, whereas the outsider Abdulwahab was connected to groups and his acts explained on a more structural level. The results have also shown how deeply connected terrorism and Islam are, which especially came through in the articles about Breivik, a Christian ethnic Norwegian man. / Denna kvalitativa textanalysstudie har undersökt medias framställning av Taimour Abdulwahab, Anders Behring Breivik och deras respektive terrordåd. Syftet var att undersöka tidningars framställning av terrorister, där ena terroristen tillhör en vi-grupp och den andra en dem-grupp. Den avser även att se om media reproducerar mekanismer som upprätthåller klyftan mellan vi och dem i sin rapportering av terrordåden. För att svara på forskningsfrågorna har vi tagit hjälp av den medievetenskapliga teorin om dagordningen och dess byggstenar samt sociologerna Norbert Elias och John L. Scotsons teori om etablerade och outsiders. Analysen av artiklar från de två första dagarna efter dåden i Expressen och Aftonbladet visade en skillnad i framställningen hos den etablerade Breivik, som framställdes på ett individuellt plan, medan outsidern Abdulwahab kopplades ihop med grupper och förklarades av strukturella skäl. Resultaten har även visat att terrorism är starkt ihopkopplat med religionen islam, även i Breiviks fall, som inte är muslim.

Made available in DSpace on 2016-06-02T20:36:58Z (GMT). No. of bitstreams: 1 DissWOM.pdf: 867642 bytes, checksum: a5425baf394bc1447e17847d5fd1c4ab (MD5) Previous issue date: 2006-03-02 / Financiadora de Estudos e Projetos / The legislation is evolving towards the establishment of restrictions to the concentration of Cr(VI), the most toxic redox form of chromium, in solid materials. This aspect has stimulated the development of sample preparation procedures for redox speciation analysis of chromium in solid samples. In the work here described it was studied procedures for Cr(VI) extraction in solid samples using alkaline solutions. Molecular absorption spectrophotometry based on 1,5 - diphenylcarbazide as chromogenic reagent was used for the determination of Cr(VI). The quantification of Cr(III) was carried out by the subtraction of the total chromium concentration and the concentration of Cr(VI). The samples employed were: soils, cements, cementrelated materials, nutritional complements and metallic components. The extractor solution composed by 0.10 mol L-1 Na2CO3 presented good performance for solid samples. Tests of stability of Cr(VI) indicated that reduction of Cr(VI) to Cr(III) did not occur in the adopted extraction conditions, even in the presence of significant amounts of Cr(III). The diphenylcarbazide method presents good sensitivity for the determination of Cr(VI) in extracts, however the presence of organic matter in the soil samples caused interferences. The total chromium concentrations were determined using either FAAS or ICP OES after complete decomposition of the samples. Sample preparation procedure for total chromium determination was implemented according to the type of sample. Cement samples and cement-related materials were decomposed by fusion. On the other hand, all the other samples were microwave-assisted digested using high pressure vessels. The main limitation of the studied procedures is the evaluation of accuracy because of the lack of standard reference materials. / A legislação está se desenvolvendo no sentido de estabelecer restrições à concentração de Cr(VI), espécie redox mais tóxica do elemento cromo, em materiais sólidos. Esse aspecto tem estimulado estudos referentes à etapa de preparo de amostra para análise de especiação redox de cromo em amostras sólidas. Neste trabalho avaliou-se procedimento de extração de Cr(VI) em materiais sólidos utilizando soluções alcalinas. A espectrofotometria de absorção molecular utilizando 1,5 - difenilcarbazida como reagente cromogênico foi empregada para a determinação de Cr(VI) nos extratos. A quantificação de Cr(III) foi realizada pela subtração do teor de cromo total e o teor de Cr(VI). As amostras utilizadas no trabalho foram: solos, cimentos, derivados de cimento, multimisturas e peças metálicas. O extrator 0,10 mol L-1 Na2CO3 apresentou boa aplicabilidade para amostras sólidas. Testes de estabilidade de íons Cr(VI) indicaram que reduções de Cr(VI) a Cr(III) não ocorreram nas condições de extração empregadas, mesmo na presença de concentrações significativas de íons Cr(III). O método da difenilcarbazida é sensível e adequado para a determinação de Cr(VI) nos extratos, contudo a presença de matéria orgânica nas amostras de solo causou interferências. As análises de cromo total foram feitas empregando as técnicas de FAAS e ICP OES após completa decomposição das amostras. O método de preparo de amostra utilizado para a determinação de cromo total variou de acordo com o tipo de amostra, sendo que para amostras de cimento e derivados aplicou-se fusão e para as demais amostras adotou-se procedimento de digestão em forno de microondas com cavidade e frascos fechados. A maior limitação dos procedimentos estudados foi a comprovação da exatidão devido à praticamente inexistência de materiais de referência certificados.

Water pollution, especially caused due to the indiscriminate release of heavy metals as a result of anthropogenic activities is a major concern worldwide. Chromium, a heavy metal, regardless of its commercial importance has found to be a potent water pollutant. Chromium generally exist as hexavalent (Cr(VI)) and trivalent (Cr(III)) chromium in the environment. Cr(VI) is ascertained to be more toxic compared to Cr(III) and the former is identified as a carcinogen by the World Health Organisation (WHO). Some of the conventional methods currently available for chromium pollution mitigation are not cost effective and most importantly lead to secondary pollution in the form of sludge. Bioremediation is a promising alternative technique which is also ecofriendly. The bioremediation process utilises biological materials such as microorganisms and agricultural byproducts. Biosorption is a bioremediation process that is a surface related phenomenon involving adsorption of contaminant chromium ions onto the binding sites of the biosorbents. In addition to the efforts made to the remediation of chromium, continuous monitoring of chromium contaminant level in polluted water bodies becomes imperative. The present research study encompasses findings related to bioremediation and detection of chromium ions using bacterial cells. The first part of the dissertation involves studies pertaining to the bioremediation of chromium ions using different bacterial strains as biosorbent. For the study, bacterial strains procured from a microbial culture collection bank as well as those isolated from chromium polluted water samples collected from an industrial site were assessed for their ability to remediate chromium. The next aim of the study was to elucidate the mechanisms involved in the bioremediation of chromium ions by the bacterial cells for which the different characterisation methods such as, Fourier Transform Infrared (FTIR) spectroscopy, Energy Dispersive Spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and zeta potential measurements which enabled to throw light on the reactions occurring at the bacterial cell surface-chromium solution interface. The later part of the study examines the capability of the bacterial strains used in the bioremediation studies as sensors for the detection of Cr(VI) and Cr(III) ions by adopting electroanalytical techniques, such as, Cyclic Voltammetry (CV) and Cathodic Stripping Voltammetry (CSV), wherein a microbe-modified Carbon Paste Electrode (CPE) was used as the working electrode in a typical three electrode electrochemical cell with Saturated Calomel Electrode (SCE) and platinum wire used as the reference and auxiliary electrodes respectively. The key objectives of the present study are as follows: (i) To study the bioremediation of Cr(VI) and Cr(III) ions present in aqueous solutions using two bacterial strains procured from a microbial culture collection bank as biosorbents. The bacterial strains used were Corynebacterium paurometabolum (Cp), a Gram positive bacterium and Citrobacter freundii (Cf), a Gram negative bacterium. The various factors affecting the biosorption process are to be investigated. (ii) To isolate and identify bacterial strains from water samples collected from chromium contaminated mining site in Sukinda, Odisha, India, by adopting appropriate microbiological and molecular biological procedures. (iii) To study the various factors affecting bioremediation of Cr(VI) using the mine isolates (Chromobacterium sp. (Cb) and Sphingopyxis sp. (Sp)) both Gram negative, as biosorbents. (iv) To elucidate the mechanisms adopted by the chosen bacterial cells in the bioremediation of chromium. (v) To develop an electrochemical-microbial sensor by modifying the Carbon Paste Electrode (CPE) using the bacterial strains for the detection of Cr(VI) and Cr(III) ions present in aqueous solutions. (vi) To determine the capability of the developed sensor in the detection of Cr ions in mine water samples collected from Sukinda chromite mine in Odisha, India. (vii) To elucidate the mechanisms occurring at the bio-modified electrode–solution interface. A compendious description of the findings from the present work is given below: The capability of two bacterial strains procured from a microbial culture collection bank (MTCC), Corynebacterium paurometabolum (Gram positive bacterium) and Citrobacter freundii (Gram negative bacterium) as biosorbents for Cr (VI) and Cr(III) ions was assessed. Further, it became of interest to translate the studies related to bioremediation to an industrial situation. For this, bacterial strains were isolated from chromium contaminated water samples collected from surface water of Sukinda chromite mine in Odisha, India. Based on detailed microbiological and molecular biological protocols, two strains of bacteria were identified and characterised as Chromobacterium sp. and Sphingopyxis sp. The bioremediation efficiency of the strains was evaluated taking into consideration the various factors such as effect of contact time of bacterial cells with the chromium ions, pH of the chromium ion solution, biomass loading and initial chromium ion concentration. The Cr(VI) biosorption efficiency obtained for C. freundii was found to be about 59 %, followed by Sphingopyxis sp. and C. paurometabolum ≈ Chromobacterium sp. in the range of 50 % to 55 %. Subsequent to interaction of the bacterial cells with the Cr(VI) solution, the residual chromium was found to be in the form of Cr(III) ions. Hence, complete bioremediation of Cr(VI) could be achieved in terms of both biosorption and bioreduction processes using all the bacterial strains. It was found that the bioreduction process occurring in conjunction with the biosorption process resulted in nil concentration of Cr(VI) ions in the bulk solution. Similarly, studies related to bioremediation of Cr(III) using C. paurometabolum and C. freundii bacterial strains were also performed with higher biosorption efficiency achieved for the former, 50 % compared to 30 % obtained for C. freundii bacterial cells. The bioremediation of Cr(III) ions by the bacterial cells is achieved by the biosorption process. Biosorption of Cr ions by all the bacterial strains were found to follow a typical Langmuirian behaviour. The bioremediation process by the bacterial strains was also evaluated using suitable kinetic models and the results indicated that the bioremediation of Cr(VI) and Cr(III) by C. paurometabolum and C. freundii respectively followed pseudo first order kinetics, while the bioremediation of Cr(VI) by C. freundii, Chromobacterium sp. and Sphingopyxis sp. followed pseudo second order kinetics. It becomes of importance to ascertain the mechanisms of bioremediation of chromium ions by the bacterial cells and for this, different characterisation methods were adopted that helped in deducing the reactions occurring at the bacterial cell surface-chromium solution interface. The involvement of chemical forces in the bioremediation process was corroborated by the achievement of only partial desorption of chromium ions from the biosorbed bacterial cells. This was further confirmed by the Gibbs free energy (∆G) values, which were found to be in the range of -25 to -30 kJ/mol. FTIR spectral studies provided evidence in support of the key functional groups present on the bacterial cell surface such as, –OH, -COOH and –NH, which facilitated the binding with chromium. The EDS data for chromium biosorbed bacterial cells showed peaks corresponding to chromium, thereby confirming the binding of chromium by the bacterial cells. The redox state of chromium bound on the bacterial cell surface was determined with the help of XPS analysis. In the Cr2p XPS spectra obtained for the bacterial cells interacted with Cr(VI), it was interesting to observe a peak corresponding to Cr(III) in addition to Cr(VI), unequivocally indicating that the Cr(III) formed via bioreduction was not only released into the bulk solution but also got biosorbed on the bacterial cell surface. Apparent shifts in the binding energy values for the bacterial cells interacted with chromium were observed in the spectra recorded corresponding to C1s, O1s, N1s, P2p and S2p as compared to the spectra obtained for the bacterial cells alone. This attests to the fact that the functional groups corresponding to the elements mentioned are involved in chemical interaction with the chromium ions or are involved in the donation of electrons to bring about reduction of Cr(VI) to the less toxic Cr(III). The variation in the charge of the bacterial cell surface before and after interaction with chromium ions was monitored by performing zeta potential measurements as a function of pH. The surface charge of the bacterial cells alone was found to be negative over a wide range of pH. Subsequent to interaction of the bacterial cells with the negatively charged oxyanions of Cr(VI) ions, the surface charge was observed to be less electronegative, which further confirmed the binding of the positively charged Cr(III) ions formed via bioreduction on the bacterial cell surface. Similar results were also observed in the case when cells were allowed to interact with Cr(III) ions. The shifts in the iso-electric point for bacterial cells interacted with chromium ions further testified to the involvement of chemical binding forces in the bioremediation process. The findings obtained from the different characterisation methods enabled in understanding the reactions that are occurring at the bacterial cell surface-Cr solution interface. Initially, biosorption via electrostatic interaction of negatively charged oxyanions of Cr(VI) with the positively charged amino groups present on the bacterial cell surface takes place. Subsequent to the biosorption of Cr(VI) ions, the adjacent electron donating functional groups containing ligands present on the bacterial cell surface reduce Cr(VI) to Cr(III) via the reactions shown below: Bioreduction involving –OH group Bioreduction involving –SH group It can be seen that, the reactions involving bioreduction of Cr(VI) in the form of chromate oxyanion to Cr(III) involving hydroxyl and thiol group present on the bacterial cell surface result in the formation of intermediates, chromate-oxy and chromate-thio ester respectively. These intermediates facilitate the transfer of electrons from oxygen/sulphur donor centers to Cr(VI) acceptor molecule, thereby resulting in the reduction of Cr(VI) to Cr(III). The Cr(III) ions thus formed are then either released into the bulk solution or get complexed with the binding groups present on the bacterial cell surface. The next objective was to explore the potential of bacterial strains as sensors for the detection of Cr(VI) and Cr(III) ions. The chromium ions were detected using CV and CSV, both of which are electroanalytical techniques. For this, CPE was coated with the bacterial strains, C. paurometabolum, C. freundii, Chromobacterium sp. and Sphingopyxis sp., and the modified electrode was used as the working electrode in a typical three electrode electrochemical cell. These biosensors developed using each of the aforementioned strains resulted in a ~ 2 to 2.5 fold improved performance compared to the bare CPE for the detection of Cr(VI) ions, due to the binding ability of the various functional groups present on the bacterial cell surface. The lower limit of detection (LLOD) obtained for Cr(VI) and Cr(III) ions using CV technique was found to be 1x10-4 M and 5x10-4 M respectively. The LLOD was further improved to 1x10-9 M and 1x10-7 M for Cr(VI) and Cr(III) respectively using CSV. From the voltammograms obtained, it was postulated that the different functional groups present on the bacterial cell surface facilitate the detection of the chromium ions. Additionally, the developed microbial sensors were also found to be capable of detecting Cr(VI) ions in mine water samples collected from Sukinda chromite mine Odisha, India. In summary, the mechanisms of bioremediation of toxic Cr(VI) ions have been delineated as comprising of both biosorption and bioreduction processes. The residual Cr(VI) concentration subsequent to the treatment of the Cr(VI) aqueous solution with the bacterial cells was found to be nil, which meets the regulatory limit of 0.05 mg L-1 put forward by the US-Environmental Protection Agency (EPA) for a safe effluent discharge. Moreover, it has also been demonstrated that the chosen bacterial strains could be used as sensors for the detection of upto nanomolar concentration of Cr(VI) ions, under optimum conditions.

Desinfecção é um processo empregado no tratamento de água potável e de efluente líquido. Cloro e seus derivados (desinfetantes mais utilizados) apresentam o inconveniente de formar produtos perigosos à saúde, resultantes de reações com compostos orgânicos. Os compostos Trihalometanos (THMs) e os ácidos haloacéticos (HAAs) estão entre os principais grupos de subprodutos encontrados. Vários fatores interferem na formação de tais produtos, como por exemplo: pH, temperatura, tempo reacional, nitrogênio amoniacal etc. O presente trabalho apresenta um estudo da geração de subprodutos provindos da desinfecção de quatro distintos efluentes de estações de tratamento biológico. Hipoclorito de sódio e ferrato(VI) de sódio foram usados como desinfetantes em concentrações e tempos reacionais variados. Análises de pH, demanda química de oxigênio, nitrogênio amoniacal, cloro combinado, THMs e HAAs foram realizadas. A concentração dos subprodutos foi proporcional à concentração e ao tempo reacional do desinfetante hipoclorito de sódio. Para a mais alta concentração empregada de hipoclorito (20 mg L-1) e maior tempo reacional (168 h), o total de THMs não excedeu ao valor máximo de descarga permitido para efluentes tratados (1 mg L-1 de clorofórmio). Os THMs e os HAAs apresentaram-se inversamente correlacionados com a concentração de nitrogênio amoniacal presente no efluente. Para o desinfectante ferrato(VI) não houve formação de subprodutos halogenados, uma vez que este desinfetante não contribui com átomos de cloro.

Submitted by Francisco Costa (xcosta@ufba.br) on 2013-10-03T00:14:12Z No. of bitstreams: 1 SAMPAIO Sanane. Grandezas do ínfimo (diss 2013).pdf: 198250811 bytes, checksum: 57a3e3bb2a2c61d68b256dcec1cded89 (MD5) / Approved for entry into archive by Edilene Costa(ec@ufba.br) on 2013-10-03T22:33:01Z (GMT) No. of bitstreams: 1 SAMPAIO Sanane. Grandezas do ínfimo (diss 2013).pdf: 198250811 bytes, checksum: 57a3e3bb2a2c61d68b256dcec1cded89 (MD5) / Made available in DSpace on 2013-10-03T22:33:01Z (GMT). No. of bitstreams: 1 SAMPAIO Sanane. Grandezas do ínfimo (diss 2013).pdf: 198250811 bytes, checksum: 57a3e3bb2a2c61d68b256dcec1cded89 (MD5) / CNPQ / Partindo do pressuposto de que a cidade está repleta de espaços que sobram, que são resíduos, vai-se à sua procura em locais de Salvador, em muitos aspectos antagônicos entre si, que são dois conjuntos habitacionais – Fazenda Grande II e de Cajazeira VI – e a Av. Tancredo Neves. Ao tempo em que estes espaços eram identificados, foi-se construindo uma reflexão sobre o que são, como se apresentam no contexto em que estão inseridos, como são produzidos, qual o sentido deles e quais as possibilidades de alteração do seu caráter residual. Para tanto, os principais referenciais teóricos utilizados foram desenvolvidos por Henri Lefebvre no livro “La production de l’espace”, de 1974, e por Michel de Certeau e Pierre Mayol nos dois volumes do livro “A invenção do cotidiano”, publicados originalmente em 1980 e 1994. Os espaços residuais são espaços livres, por vezes são vazios na cidade, e estão inseridos num modo de construir a cidade que preconiza pela racionalidade e planejamento. Foi observado, contudo, que há resíduos que de alguma maneira estão ocupados ou, quando vazios, não são “vazios urbanos” no sentido em que esta expressão normalmente é utilizada. Ademais, suas especificidades são pouco abordadas nos estudos sobre espaços livres e são, sobretudo, espaços que explicitam aspectos da irracionalidade de modos hegemônicos de produzir a cidade. Nos estudos de caso aqui abordados, os espaços residuais são elementos excluídos do processo de projetação e de planejamento, ou seja, da representação do espaço, e, sendo materializados na cidade, podem ser absorvidos ou não pela dinâmica urbana. Sendo absorvidos, isso significa que estes espaços são percebidos e vividos, isto é, são produzidas práticas espaciais e espaços de representação, e, neste caso, reverte-se o caráter residual destes espaços. Esta produção é feita mediante práticas cotidianas que, nos conjuntos habitacionais e na avenida, objetivam suprir uma demanda privada de seus moradores ou usuários, sendo conduzidas por processos de reconhecimento e de negociação e da construção de conveniências sociais. Não obstante, há exemplos de grupos que propõem e efetivam apropriações de espaços residuais sem que isso resulte em sua privatização. / Salvador

Studiens syfte ligger på medverkande arbetslags arbetssätt med interkulturalitet samt hur de planerar och arbetar utifrån ett interkulturellt perspektiv. Studien genomsyras av ett tänk kring vi och de andra. Det svenska samhället präglas av många olika hemkulturer och med detta i åtanke anser vi att människor behöver få en förståelse och visa solidaritet för varandra, detta för att kunna skapa ett hållbart samhälle. Tidigare forskning beskriver även att ett tänk kring vi och de andra måste försvinna för att alla människor i samhället ska kunna se varandra som likvärdiga. Pedagoger i förskolan har som uppdrag att bland annat föra det svenska kulturarvet såsom traditioner och högtider vidare till barnen i verksamheten. I studien samlades data in genom ett kvalitativt frågeformulär där sex arbetslag från två olika förskolor deltog. Resultatet visar att arbetslagen arbetar interkulturellt genom att intressera sig för barnens olika hemkulturer och hemspråk. Studien visar även hur jul, påsk, midsommar och barnens födelsedagar är de högtider och traditioner som är centrala i de förskolor som studien utgår från. I arbetslagen utgår pedagogerna från svenska normer och deras egen hemkultur när de väljer vilka högtider och traditioner de ska uppmärksamma tillsammans med barnen. Analysen av resultatet fokuserar på hur pedagogerna i studien anser att ett tänk kring vi och de andra inte får förekomma men trots detta är ändå en teori kring vi och de andra det som genomsyrar hela resultatet.

abstract: The research described in this dissertation has involved the use of transmission electron microcopy (TEM) to characterize the structural properties of II-VI and III-V compound semiconductor heterostructures and superlattices. The microstructure of thick ZnTe epilayers (~2.4 µm) grown by molecular beam epitaxy (MBE) under virtually identical conditions on GaSb, InAs, InP and GaAs (100) substrates were compared using TEM. High-resolution electron micrographs revealed a highly coherent interface for the ZnTe/GaSb sample, and showed extensive areas with well-separated interfacial misfit dislocations for the ZnTe/InAs sample. Lomer edge dislocations and 60o dislocations were commonly observed at the interfaces of the ZnTe/InP and ZnTe/GaAs samples. The amount of residual strain at the interfaces was estimated to be 0.01% for the ZnTe/InP sample and -0.09% for the ZnTe/GaAs sample. Strong PL spectra for all ZnTe samples were observed from 80 to 300 K. High quality GaSb grown by MBE on ZnTe/GaSb (001) virtual substrates with a temperature ramp at the beginning of the GaSb growth has been demonstrated. High-resolution X-ray diffraction (XRD) showed clear Pendellösung thickness fringes from both GaSb and ZnTe epilayers. Cross-section TEM images showed excellent crystallinity and smooth morphology for both ZnTe/GaSb and GaSb/ZnTe interfaces. Plan-view TEM image revealed the presence of Lomer dislocations at the interfaces and threading dislocations in the top GaSb layer. The defect density was estimated to be ~1 x107/cm2. The PL spectra showed improved optical properties when using the GaSb transition layer grown on ZnTe with a temperature ramp. The structural properties of strain-balanced InAs/InAs1-xSbx SLs grown on GaSb (001) substrates by metalorganic chemical vapor deposition (MOCVD) and MBE, have been studied using XRD and TEM. Excellent structural quality of the InAs/InAs1-xSbx SLs grown by MOCVD has been demonstrated. Well-defined ordered-alloy structures within individual InAs1-xSbx layers were observed for samples grown by modulated MBE. However, the ordering disappeared when defects propagating through the SL layers appeared during growth. For samples grown by conventional MBE, high-resolution images revealed that interfaces for InAs1-xSbx grown on InAs layers were sharper than for InAs grown on InAs1-xSbx layers, most likely due to a Sb surfactant segregation effect. / Dissertation/Thesis / Ph.D. Physics 2012

abstract: A dual chamber molecular beam epitaxy (MBE) system was rebuilt for the growth of 6.1 Angstrom II-VI and III-V compound semiconductor materials that are to be used in novel optoelectronic devices that take advantage of the nearly continuous bandgap availability between 0 eV and 3.4 eV. These devices include multijunction solar cells and multicolor detectors. The MBE system upgrade involved the conversion of a former III-V chamber for II-VI growth. This required intensive cleaning of the chamber and components to prevent contamination. Special features including valved II-VI sources and the addition of a cold trap allowed for the full system to be baked to 200 degrees Celsius to improve vacuum conditions and reduce background impurity concentrations in epilayers. After the conversion, the system was carefully calibrated and optimized for the growth of ZnSe and ZnTe on GaAs (001) substrates. Material quality was assessed using X-ray diffraction rocking curves. ZnSe layers displayed a trend of improving quality with decreasing growth temperature reaching a minimum full-width half-maximum (FWHM) of 113 arcsec at 278 degrees Celsius. ZnTe epilayer quality increased with growth temperature under Zn rich conditions attaining a FWHM of 84 arcsec at 440 degrees Celsius. RHEED oscillations were successfully observed and used to obtain growth rate in situ for varying flux and temperature levels. For a fixed flux ratio, growth rate decreased with growth temperature as the desorption rate increased. A directly proportional dependence of growth rate on Te flux was observed for Zn rich growth. Furthermore, a method for determining the flux ratio necessary for attaining the stoichiometric condition was demonstrated. / Dissertation/Thesis / M.S. Electrical Engineering 2012

Realizamos um estudo transversal prospectivo com o objetivo de determinar a prevalência de apnéia obstrutiva do sono em um grupo de pacientes sul-americanos com mucopolissacaridose tipo VI sem tratamento prévio ou atual com terapia de reposição enzimática ou transplante de medula óssea. Os critérios de inclusão foram: ter 4 anos ou mais de idade e confirmação bioquímica da doença (níveis reduzidos da atividade da arilsulfatase B, aumento de glicosaminoglicanos (GAGs) urinários e atividade normal de outra sulfatase). Foram avaliados 28 pacientes através de anamnese, exame físico, ecocardiograma Doppler transtorácico e polissonografia realizada em noite inteira. A amostra estudada tinha 14 (50%) meninos. No momento da avaliação, a média de idade foi de 98,5 meses e a média de idade do diagnóstico de MPS VI foi de 48,4 meses. Em 88% da amostra os sintomas iniciaram com menos de 36 meses e em 27% das famílias houve relato de consangüinidade entre os pais. As manifestações clínicas mais freqüentes durante o sono foram roncos e apnéias observadas. Ao exame físico, 78,6% apresentavam macroglossia e 82,1% deformidade torácica tipo pectus carinatum. Três (10,71%) pacientes já tinham realizado adenotonsilectomia e 6 (21,42%) adenoidectomia isoladamente. Os dados polissonográficos evidenciaram apnéia obstrutiva do sono em 23 (85,1%) pacientes, sendo 4 com transtorno leve, 5 moderado e 14 grave. A média do índice de apnéia hipopnéia (IAH) foi de 19,84 ± 26,25 eventos/hora, da saturação periférica da oxihemoglobina (SpO2) 93,25 ± 5,06%, do nadir da SpO2 80,29 ± 10,01% e do pico do dióxido de carbono final exalado (EtCO2) 44,1 ± 6,01 mmHg. A ocorrência de apnéias centrais foi rara. Quatorze indivíduos da amostra (50%) tiveram evidência de hipertensão pulmonar (HP) documentada através de ecocardiograma. Foi observada associação positiva entre a média e o nadir da SpO2 mais baixos e a presença de HP. No grupo com HP, a média e o nadir da SpO2 foram de 91,2 ± 6,4% e 75,4 ± 10,9% respectivamente, enquanto que nos pacientes sem HP os valores de média e nadir da SpO2 foram 95,3 ± 1,8% e 85,2 ± 6,1% respectivamente (p=0,037 para média; p=0,007 para nadir). A presença de apnéias observadas durante o sono foi a variável mais importante em predizer HP nessa amostra (p=0,016; OR 9,9; IC 1,5 a 63,7). As manifestações clínicas sugestivas de alterações respiratórias durante o sono não apresentaram correlação significativa com o IAH, a média e o nadir de SpO2 e o pico de EtCO2. Também não houve correlação significativa entre a excreção urinária de GAGS e a atividade enzimática com resultado da polissonografia e do ecocardiograma. Concluímos que a prevalência de apnéia obstrutiva do sono nos pacientes com mucopolissacaridose tipo VI é elevada e o nível de dessaturação apresenta correlação positiva com a presença de hipertensão pulmonar. Os sintomas durante o sono não apresentaram associação com o resultado da polissonografia. A presença de apnéias observadas durante o sono foi a variável mais importante para predizer HP. / This prospective cross-sectional study was conducted to determine the prevalence of obstructive sleep apnea in a group of South American patients with mucopolysaccharidosis type VI who had no previous or current treatment with enzyme replacement or bone marrow transplant. Inclusion criteria were: age 4 years or older; and biochemical confirmation of the disease – reduced arylsulfatase B activity, increased glycosaminoglycans (GAGs) in urine, and normal activity of at least one other sulfatase. Twenty-eight patients were examined and data were collected from clinical history, physical examination, transthoracic Doppler echocardiogram and overnight polysomnography. Of the 28 participants, 14 (50%) were boys; mean age at evaluation was 98.5 months, and mean age at MPS diagnosis, 48.4 months. Symptoms started before 38 months of age in 88% of the sample; 27% reported parental consanguinity. The most frequent clinical symptoms during sleep were snoring and witnessed apnea. Physical examination revealed that 78.6% had macroglossia, and 82.1%, pectus carinatum. The most frequent clinical symptoms during sleep were snoring and witnessed apnea. Physical examination revealed that 78.6% had macroglossia, and 82.1%, pectus carinatum. Three (10.71%) patients had already undergone adenotonsillectomy, and 6 (21.42%), isolated adenoidectomy. Polysomnography results showed that 23 (85.1%) patients had obstructive sleep apnea: 4 mild, 5 moderate, and 14 severe. Mean apnea-hypopnea index (AHI) was 19.84 ± 26.25 events/hour, oxygen saturation (SpO2), 93.25 ± 5.06%, SpO2 nadir, 80.29 ± 10.01%, and peak end-tidal carbon dioxide (EtCO2), 44.1 ± 6.01 mmHg. Central apneas were rare. Pulmonary hypertension (PH) was detected by echocardiography in 14 (50%) patients. Lower SpO2 mean and nadir were positively associated with PH. In the group of patients with PH, SpO2 mean and nadir were 91.2 ± 6.4% and 75.4 ± 10.9%, and in the group without PH, 95.3 ± 1.8% and 85.2 ± 6.1% (p=0.037 for mean; p=0.007 for nadir). Witnessed apneas during sleep were the most important variable to predict PH in this sample (p=0.016; OR 9.9; CI, 1.5 to 63.7). Clinical signs suggestive of respiratory abnormalities during sleep were not significantly correlated with AHI, SpO2 mean and nadir, or peak EtCO2. There was no significant correlation between GAGs in urine or enzyme activity and polysomnography or echocardiogram results. The prevalence of obstructive sleep apnea in patients with mucopolysaccharidosis type VI was high, and the level of desaturation was positively correlated with the presence of pulmonary hypertension. Symptoms observed during sleep were not associated with polysomnography results. Witnessed apneas during the sleep were the most important variable to predict PH.