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Search Results: 1 - 10 of 588445 matches for " Júlio César R Azevedo "
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SPECTROSCOPIC STUDY OF HUMIC SUBSTANCES EXTRACTED FROM WATER, SOIL AND SEDIMENT SAMPLES OF THE PATOS LAKE, MS, BRAZIL
Júlio César R Azevedo, Mariana Carolina Teixeira e Jorge Nozaki
SaBios : Revista de Saúde e Biologia , 2006,
Abstract: Humic substances (HSs) were extracted from samples collected in 4 areas of sediment, water and soil from Patos′ lake - MS. The humic substances from the water were extracted according to Thurman and Malcolm methods (1981) and, those from sediment and soil were extracted as proposed by the International Society of Humic Substances (ISHS). The following spectroscopic techniques were performed in this study: ultraviolet and visible (UV-Vis) and fluorescence emission. The effects of ambient factors as concentration and variations of pH in fluorescence emission of humic substances (fulvic and humic acids) were evaluated. It was observed that the UV-Vis technique and the intensity of emitted fluorescence from humic substances extracted from water has shown linear correlation with the variation of fulvic acid (7.3 the 35.5 mg L-1) and of humic acid (4.8 the 23.9 mg L-1) concentrations, considering just dissolved organic carbon. However, for pH variation (acid, neutral and alkaline media) significant variations were not observed in both, UV-Vis and fluorescence emission techniques.
Evaluation of Dissolved Organic Carbon Using Synchronized Fluorescence Emission Spectra and Unsupervised Method of Principal Component Analysis (PCA) and Independent Component Analysis (ICA)  [PDF]
Tais Cristina Filippe, Luana Mayumi Takahasi Marques, Heloise G. Knapik, Júlio César Rodrigues de Azevedo, Jorge Costa Pereira
Journal of Water Resource and Protection (JWARP) , 2019, DOI: 10.4236/jwarp.2019.113015
Abstract: Dissolved organic matter (DOM) can be originated from autochthonous or allochthonous sources, where allochthonous DOM can be from pedogenic sources (humic substances—HSs) or anthropogenicsources (wastewater). The analysis of fluorescence emission, excitation, synchronous or excitation-emission matrix (EEM) have been used to identify the main source or probable contribution of dissolved compounds, such as humic acids (HA), fulvic acids (FA) and dissolved organic carbon (DOC) from sewage, but does not quantify. Fluorescence emission is a powerful technique to detect and qualify organic dissolved compounds but fails in quantitative aspects. In this work, we propose an in situ method for direct determination of DOC using synchronous fluorescence spectra with independent component analysis (ICA). Well known standard solutions were used for method development and validation. In this work, we show that it is possible to predict the number of independent contributions using an unsupervised method based on iterative Principal Component Analysis and Independent Component Analysis (PCA-ICA) approach over combined matrix results. Within these results it’s also possible to see that with a very small amount of independent components it is possible to describe environmental samples of HA, FA and primary productivity (PP).
Análise de fluorescência de substancias húmicas extraídas da água, solo e sedimento da Lagoa dos Patos - MS
Azevedo, Júlio César Rodrigues de;Nozaki, Jorge;
Química Nova , 2008, DOI: 10.1590/S0100-40422008000600010
Abstract: the humic substances were extracted from sediments, water and soil close to the lagoa dos patos-ms. the characterization was performed through fluorescence emission. in the hss it is possible to see strong indications of incorporation of compounds originating from lignin degradation, confirmed by fluorescence emission (eem and synchronous spectra). these differences observed in hss may be due to tropical regions displaying a great variety of vascular plants and aquatic macrophytes that contribute natural organic matter. the seasonality effect also causes the entrance of pedogenic material and the suspension of sediments by the action of winds.
Spatial and seasonal distribution of chromophoric dissolved organic matter in the Upper Paraná River floodplain environments ( Brazil)
Teixeira, Mariana Carolina;Azevedo, Júlio César Rodrigues de;Pagioro, Thomaz Aurélio;
Acta Limnologica Brasiliensia , 2011, DOI: 10.1590/S2179-975X2012005000011
Abstract: aim: our aim was to identify dissolved organic matter (dom) main sources in environments of the upper paraná river floodplain and their seasonal and spatial variation. methods: ultraviolet-visible and fluorescence spectroscopy were utilized. the samples were obtained from november 2007 to september 2008 in six lakes of the floodplain. results: dom quality differs among environments and also between rainy and dry season. the environments connected with paraná river showed a high variation on the allochthonous/autochthonous proportion. aquatic macrophytes might represent an important contribution to dom in gar?as and osmar lakes. conclusions: in general, environments connected to paraná river have a greater influence of autochthonous doc, while the others are most influenced by allochthonous inputs.
Spatial and seasonal distribution of chromophoric dissolved organic matter in the Upper Paraná River floodplain environments ( Brazil) Distribui o espacial e sazonal da matéria organica dissolvida cromófora em ambientes da planície de inunda o do alto rio Paraná (Brasil)
Mariana Carolina Teixeira,Júlio César Rodrigues de Azevedo,Thomaz Aurélio Pagioro
Acta Limnologica Brasiliensia , 2011,
Abstract: AIM: Our aim was to identify dissolved organic matter (DOM) main sources in environments of the Upper Paraná River floodplain and their seasonal and spatial variation. METHODS: Ultraviolet-visible and fluorescence spectroscopy were utilized. The samples were obtained from November 2007 to September 2008 in six lakes of the floodplain. RESULTS: DOM quality differs among environments and also between rainy and dry season. The environments connected with Paraná River showed a high variation on the allochthonous/autochthonous proportion. Aquatic macrophytes might represent an important contribution to DOM in Gar as and Osmar lakes. CONCLUSIONS: In general, environments connected to Paraná River have a greater influence of autochthonous DOC, while the others are most influenced by allochthonous inputs. OBJETIVO: O objetivo deste estudo foi identificar a origem da matéria organica dissolvida (MOD) em ambientes da planície de inunda o do alto rio Paraná e sua varia o sazonal e espacial. MéTODOS: Para tal, foram utilizadas técnicas de espectroscopia ultravioleta-visível e de fluorescência. As amostras foram coletadas no período de novembro de 2007 a setembro de 2008 em seis lagoas da planície de inunda o. RESULTADOS: A qualidade da MOD difere entre ambientes e também entre as esta es seca e chuvosa. Os ambientes conectados ao rio Paraná apresentaram grande varia o na propor o autóctone/alóctone. Macrófitas aquáticas podem representar uma contribui o importante à MOD nas lagoas Gar as e Osmar. CONCLUS ES: Em geral, ambientes conectados ao rio Paraná têm maior influência de COD autóctone, enquanto os demais têm maior influência de COD alóctone.
Siting Study of Solar Thermoelectric Plants in the State of Minas Gerais  [PDF]
Chigueru Tiba, Ruibran Januário dos Reis Reis, Júlio César Ezequiel da Costa, Ver?nica Wilma Bezerra Azevedo, J?ao Francisco Abreu, Melina Amoni Silveira Alves, Daniel Pereira Guimar?es, Marco Aurélio Dumont Porto
Journal of Geographic Information System (JGIS) , 2014, DOI: 10.4236/jgis.2014.65037
Abstract: The generation of heliothermal electricity has received increasing attention throughout the world in countries such as Spain, the USA, Germany and many others. In Brazil, this type of energy generation in the form of large projects (above 80 MW) remains unexplored. However, it is known that in the country, there are extensive areas of normal direct irradiation with high intensity and a low seasonality factor, especially in the semiarid regions in Brazil, mainly the North and Northeast of Minas Gerais. Moreover, these Minas Gerais regions have other significant characteristics for the installation of these plants: proximity to transmission lines, flatness, the fact that the respective vegetation is not endangered, a suitable land use profile (availability of land not used in agriculture), low wind speed, low population density, and, most recently, an increase in the demand for local electric energy due to the economic growth above the Brazilian average rate. Furthermore, the introduction of solar plants in that region, due to its distributed nature, will bring development and growth to the region (normally poor) by generating employment and income. This article presents a study of the optimal location of thermoelectric plants in the semiarid regions of Minas Gerais, conducted with Geographical Information System (GIS) technology. GIS consists of a set of specialised resources that allow the manipulation of spatial data, bringing efficiency and agility in the identification of suitable places for the installation of solar plants, while simultaneously enabling the consideration of future scenarios for energy planning, with its respective impact, costs and benefits. The study has identified very promising solar irradiation levels for the electric generation by solar energy, whether thermoelectric or photovoltaic, reaching an annual solar irradiation of 2700 kWh/m2 in the summer and in the range of 2200 - 2400 kWh/m2 on an annual basis. This area includes a vast region in the North/Northeast of the state, which also has continuous and flat regions, with slopes inferior to 3%; in addition, high-quality hydro resources are abundant and well distributed. Furthermore, the Minas Gerais region has few areas with high agriculture profile and reduced quantity of protected units.
Análise da associa??o entre saneamento e saúde nos estados Brasileiros: estudo comparativo entre 2001 e 2006
Teixeira, Júlio César;Gomes, Maria Helena Rodrigues;Souza, Janaina Azevedo de;
Engenharia Sanitaria e Ambiental , 2011, DOI: 10.1590/S1413-41522011000200014
Abstract: in a context of poor investment in sanitation, teixeira e guilhermino (2006) studied the association between the sanitation conditions and the epidemiological indicators in the brazilian states, based on secondary data from the database from idb (2003) of the ministry of health. since 2003, investments in basic sanitation in brazil had an expressive increase. thus, the present paper had as a purpose to test the hypothesis that the improvement in the coverage by basic sanitation services from 2001 to 2006 was an investment capable to improve the studied health indicators in the brazilian states. it has been concluded that there was an improvement in the health indicators, which is still not expressive, being of the most importance the use of epidemiological and social development indicators in the priority of investments in basic sanitation in brazil.
Métodos de controle de plantas daninhas no cafeeiro afetam os atributos químicos do solo
Alcantara, Elifas Nunes de;Nóbrega, Júlio César Azevedo;Ferreira, Mozart Martins;
Ciência Rural , 2009, DOI: 10.1590/S0103-84782009000300018
Abstract: in agricultural ecosystems under coffee cultivation, soil management is based on liming, fertilizers and weed control. alternatives that preserve or increase soil organic matter content are considered when the sustainability is the goal. this study was conducted to evaluate the chemical attributes of a dystroferric red latosol (oxisols) under coffee cultivation submitted to 15 years of weed control methods. seven interrows coffee plant weed control methods were used; a mower (rc), tanden disk harrow (gr), rotative hoe (er), pre-emergence herbicide (hpre), post-emergence herbicide (hpos), hand hoe (cm) and no interrows control (test). the p, k+, ca2++ mg2+, sum of bases (sb), base saturation (v), effective (t) and potential (t) cation exchange capacity (cec) were determined in soil depth from 0-0.15m and 0.15-0.30m. test treatment affected positively the p, k+, ca2+ + mg2+ content, and effective and potential cec and v values, while the hr inversely reduced analyzed variable values. others interrows methods rc, gr, er, hpos e cm presented an intermediary conduct among the test and hpre methods on soil fertility.
Métodos de controle de plantas invasoras na cultura do cafeeiro (Coffea arabica L.) e componentes da acidez do solo
Alcantara, Elifas Nunes;Nóbrega, Júlio César Azevedo;Ferreira, Mozart Martins;
Revista Brasileira de Ciência do Solo , 2007, DOI: 10.1590/S0100-06832007000600029
Abstract: in perennial agriculture, such as coffee plantation, weeds are controlled by hand, mechanized, and chemical weeding and their combinations. methods that differ in terms of efficiency and costs have been evaluated; however, the influence of these methods on the soil chemical conditions has not been studied, particularly in the long term. this study aimed to evaluate the effect of different weed control methods on soil acidity components of a coffee plantation on a dystroferric red latosol in an experiment installed at epamig experimental station, in s?o sebasti?o do paraíso, mg, brazil. seven weed control treatments were evaluated: mower (mw), coffee tandem disk harrow (td), rotary tiller (rt), post (ch) and pre-emergency herbicide (rh) application, hand hoe (hh) and no weed control (nc). the treatments were evaluated in a randomized block design with three repetitions. soil samples were collected every two years, for each treatment, starting in 1980, in the 0-0.15 to 0.15-0.30 m soil layers and assessed for ph, al3+ (mmolc dm-3), effective acidity (h + al) (mmolc dm-3), and al3+ saturation (%). the hr system increased al3+ content and saturation and the effective acidity and reduced the ph, compared to the other weed control methods, especially the control (nc). contrarily to the rh, the nc treatment resulted in higher ph values, al3+ content and al3+ saturation in both soil layers. the mw treatment was closest to the sc treatment, while the other weed control systems did not differ significantly.
Fosfato e micorriza na estabilidade de agregados em amostras de latossolos cultivados e n o-cultivados
Nóbrega Júlio César Azevedo,Lima José Maria de,Curi Nilton,Siqueira José Oswaldo
Pesquisa Agropecuária Brasileira , 2001,
Abstract: Nos trópicos, existe escassez de informa o quanto à contribui o de espécies fúngicas do solo na forma o e estabiliza o de agregados. Este estudo teve como objetivo avaliar o efeito do histórico de uso, níveis de P, de inocula o micorrízica e cultivo com braquiária e soja em casa de vegeta o, sobre o diametro médio geométrico dos agregados (DMG), o índice de flocula o das partículas, a matéria seca das raízes, a coloniza o micorrízica e o comprimento total de hifas, em amostras de Latossolo Vermelho distrófico e Latossolo Vermelho distroférrico. Amostras dos dois solos, previamente cultivados por longos períodos, e de solos n o-cultivados, foram trazidas para casa de vegeta o, submetidas a inocula o, e a dois níveis de P, e ent o cultivadas com braquiária e soja, em dois cultivos sucessivos. Os resultados mostraram que o solo previamente cultivado apresentou menor comprimento total de hifas, menor estabilidade de agregados (menor diametro médio de agregados) e menor índice de flocula o. A inocula o propiciou maior estabilidade dos agregados, e este efeito é condicionado ao nível de P do solo e ao histórico de uso. A presen a de P promoveu, indiretamente, maior agrega o, por propiciar maior comprimento total das hifas e matéria seca de raízes.
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