Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-03-30T19:26:59Z No. of bitstreams: 1 nathanoliveirabarros.pdf: 1040154 bytes, checksum: 487237db51107acbc884e22816c55c60 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-03T18:59:43Z (GMT) No. of bitstreams: 1 nathanoliveirabarros.pdf: 1040154 bytes, checksum: 487237db51107acbc884e22816c55c60 (MD5) / Made available in DSpace on 2017-04-03T18:59:43Z (GMT). No. of bitstreams: 1 nathanoliveirabarros.pdf: 1040154 bytes, checksum: 487237db51107acbc884e22816c55c60 (MD5) Previous issue date: 2008-05-28 / Os vírus são descritos como sendo os organismos mais abundantes e dinâmicos dos ecossistemas aquáticos, eles podem influenciar tanto a composição das comunidades quanto processos biogeoquímicos e ecológicos nestes ambientes. Os vírus são responsáveis por grande parte da mortandade bacteriana e fitoplanctônica, pelo término de florações e pelo aumento da disponibilidade de carbono e nutrientes. Muitos trabalhos reportam sobre a ecologia de vírus em ambientes aquáticos temperados, entretanto para ambientes tropicais, até o presente momento existem apenas dois trabalhos. O objetivo deste trabalho foi avaliar a abundância de vírus e bactérias em sistemas aquáticos amazônicos, bem como as interações entre estas duas comunidades. Para isso foi utilizado técnicas de microscopia eletrônica e microscopia de luz. O número de vírus (VLP) variou tanto em escala temporal quanto em escala espacial, no entanto, a razão entre vírus e bactérias (VRB) se manteve estável. Em uma escala espacial a VBR esteve inversamente correlacionada com a concentração de carbono orgânico dissolvido (COD), sugerindo que lagos húmicos apresentam menor taxa de mortalidade bacteriana causada por vírus. Em média 20% das bactérias estavam infectadas com um número médio de 10 fagos por célula. O número de vírus esteve relacionado à disponibilidade de fósforo, à profundidade do lago, à entrada de luz e, principalmente à densidade bacteriana. Nossos dados são fortes evidências de que também nos ecossistemas amazônicos a maioria dos vírus são bacteriófagos e, portanto, possuem um papel fundamental no controle da comunidade bacteriana, na ciclagem de nutrientes e no fluxo de energia. / Virus are described as the most abundant and dynamic organisms in the aquatic environment, influencing communities composition and biogeochemical and ecological processes. These organisms are responsible for great part of the bacterial and phytoplanktonic mortality, for algal blooms decrease and for increasing the nutrients and carbon availability. Many previous works approach the viral ecology in temperate aquatic ecosystems, although there are only two references for the tropical area. The goal of this work was to determine the viral and bacterial abundances in Amazonian aquatic systems, as well as to evaluate the interactions between these groups. In order to achieve it, optical and electronic microscope techniques were applied. The number of viruses (VLP) varied both in temporal and in spatial scales, even though the virus/bacteria ratio was kept unaltered. In a spatial scale, VRB was correlated to the dissolved organic carbon (COD) concentration, suggesting that humic lakes present reduced rate of bacterial mortality caused by virus. In average, 20% of the bacteria were infected by 10 phagos per cell. The VLP was correlated to phosphorus availability, lake depth, light penetration, and mainly bacterial abundance. We suggest that most of the virus in Amazonian aquatic ecosystems are bacteriophages and, hence, that they play a fundamental role in controlling the bacterial community, in nutrient cycling and in energy flux.

Made available in DSpace on 2014-12-17T14:02:00Z (GMT). No. of bitstreams: 1 PatriciaLSCL.pdf: 1934431 bytes, checksum: cb552f8c167ecea1cf7b85c22d8a6a10 (MD5) Previous issue date: 2010-03-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / It is important to evaluate the quality of water for proper management of these resources, since the increase of environmental degradation and the multiple use of water resources are decreasing the quality of water consumed by living beings. The objective of this study was to characterize the phytoplankton community and its variations during periods of dray and rain in Jiqui Lake located in Parnamirim, RN. It was also aimed to analyze the physical and chemical factors of this environment, in order to contribute to the knowledge of water quality used for human consumption. The collection of water samples were carried out in September 2008 to August 2009. The collection of the phytoplankton community was carried out in four sampling sites (surface, bottom, margin of the lake without macrophytes and site dominated by macrophytes). Phytoplankton was collected using plankton net of 20?m. The analysis of nutrients and identification of phytoplankton were performed in the laboratory. The results indicate that concentration of chlorophyll a was high in the bottom with mean value of 1.07 ?gL-1 (SD ? 1.61). During the study period there was a dominance of the following species: Euglena gracilis, Trachelomonas sp, Cyclotellas sp, Gomphonema apuncto, Navicula cuspidata var. cuspidata, Navicula sp, Rhopalodia gibba. There was homogeneity between limnological values in the four study sites, with significant difference between the periods of drought and rain. The Jiqui Lake is considered oligotrophic due to its low concentrations of chlorophyll a, high transparency and low levels of nutrients. The values of BOD and chlorophyll a concentration remained below the permitted standards existing for freshwaters in Brazil, thus the water from Lake Jiqui is of good quality, suitable for human consumption. / O aumento da degrada??o ambiental e o uso m?ltiplo dos recursos h?dricos v?m diminuindo a qualidade da ?gua consumida pelos seres vivos, por isso ? importante a sua avalia??o para o adequado gerenciamento desses recursos. Este estudo teve como objetivo caracterizar a comunidade fitoplanct?nica juntamente com a sua varia??o durante os per?odos de estiagem e de chuva da Lagoa do Jiqui, localizada em Parnamirim, RN, al?m de analisar os fatores f?sico-qu?micos desses ambientes aqu?ticos, a fim de contribuir para o conhecimento da qualidade de ?gua desse manancial utilizada para o abastecimento humano. As coletas das amostras de ?gua foram realizadas de setembro de 2008 a agosto de 2009. A coleta da comunidade fitoplanct?nica foi realizada em quatro s?tios de amostragem (superf?cie, fundo, banco da macr?fitas e na margem da lagoa sem macr?fitas). O fitopl?ncton foi coletado utilizando-se uma rede de pl?ncton de 20?m. Em laborat?rio, foram realizadas as an?lises dos nutrientes e a identifica??o da comunidade fitoplanct?nica. Os resultados indicam que a concentra??o da clorofila a foi elevada no fundo com valor m?dia de 1,07 ?gL-1 (DP? 1,61). Durante o per?odo de estudo ocorreu uma domin?ncia das esp?cies Euglena gracilis, Trachelomonas sp, Cyclotellas sp, Gomphonema apuncto, Navicula cuspidata var. cuspidata, Navicula sp, Rhopalodia gibba. Houve homogeneidade entre os valores limnol?gicos nos quatro s?tios estudados, com diferen?a significativa entre os per?odos de estiagem e de chuva. A Lagoa do Jiqui ? oligotr?fica, uma vez que apresenta baixas concentra??es de clorofila a, alta transpar?ncia e baixos valores de nutrientes. Os valores da DBO e concentra??o da clorofila a se mantiveram abaixo do permitido pelos padr?es existentes para ?guas doces no Brasil, assim conferindo as ?guas da Lagoa do Jiqui de boa qualidade, adequada para o consumo humano.

This diploma thesis deals with the X-Ray crystallography study of structural changes within lithium-ion cells. First part consists of the theoretical discussion about the structural changes in commerce lithium-ion cells with focus on X-Ray crystallography. Then the ex situ, in situ and operando terms are discussed. Verification of the XRD usage is realized on the LiFePO4 material. Experimental part deals with the optimization and preparation of electrochemical cells and the measurements. Finally, results of the Rietveld analysis are discussed.