203 resultados para Calcario - Absorção


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The constant search for biodegradable materials for applications in several fields shows that carnauba wax can be a viable alternative in the manufacturing of biolubricants. Carnauba wax is the unique among the natural waxes to have a combination of properties of great importance. In previous studies it was verified the presence of metals in wax composition that can harm the oxidative stability of lubricants. Considering these factors, it was decided to develop a research to evaluate iron removal from carnauba wax, using microemulsion systems (Me) and perform the optimization of parameters, such as: extraction pH, temperature, extraction time, among others. Iron concentration was determined by atomic absorption and, to perform this analysis, sample digestion in microwave oven was used, showing that this process was very efficient. It was performed some analysis in order to characterize the wax sample, such as: attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetry (TG), differential scanning calorimetry (DSC), energy dispersive X-ray fluorescence (EDXRF), scanning electron microscopy (SEM) and melting point (FP). The microemulsion systems were composed by: coconut oil as surfactant, n-butanol as cosurfactant, kerosene and/or heptanes as oil phase, distilled water as water phase. The pH chosen for this study was 4.5 and the metal extraction was performed in finite experiments. To evaluate Me extraction it was performed a factorial design for systems with heptane and kerosene as oil phase, also investigating the influence of temperature time and wax/Me ratio, that showed an statistically significant answer for iron extraction at 95% confidence level. The best result was obtained at 60°C, 10 hours contact time and 1: 10 wax/Me ratio, in both systems with kerosene and heptanes as oil phase. The best extraction occurred with kerosene as oil phase, with 54% iron removal

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Environmental Laws and Regulations to dump wastewater are increasingly relevant and, together with pressure from environmentalists, provide awareness of academics in search of solutions. In Brazil, federal law, through Resolution No. 357 of 17/03/05 of the National Environmental Council - CONAMA, in Article 24 deals with the disposal of these effluents. Water pollution with heavy metals is concern because of the difficulty of the treatment and removal from the environment. Copper, for example, is a metallic element and in the form of salt is very soluble in water which dificults its removal. In this context, this study aims to evaluate the extraction of copper with acrylamide polymers through the process of assisted flocculation followed by filtration. Therefore, we used acrylamide polymers, produced by SNF Floerger, with varying degrees of ionicity which is the parameter examined on the extraction of copper. We used the FA polymers FA 920 SH, AH 912 SH, AN 905 SH, AN 910 SH, AN 923 SH, AN 945 SH, AN 956 SH and AN 977 SH, which have anionicities different from each other and growing in that order. The parameters temperature, pH, concentration of the copper solution and stirring speed are fixed. The polymer solution was added to a solution of 200 ppm copper, varying the concentration of polymer. After stirring, an assisted flocculation occurred followed by filtration of the effluent. The filtrate was analyzed by atomic absorption spectrophotometer and the percentage removal of copper ranged from 63 % to 97 %, noting that polymers with higher ionic charge were responsible for the highest percentage of copper extraction. The results of this study showed that these polymers can be applied in the treatment of wastewaters containing metals such as copper

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The increasing demand for natural dyes in place of synthetic ones is justified by the non-toxicity or low toxicity of the former. The synthetic dyes are associated with diseases like cancer as well as when released in the environment takes longer to degrade and the intermediates could be still more toxic. The Annatto (Bixa Orellana L.) is a carotenoid and one of the more important natural dyes used in the food industry. In the form of dye, it represents nearly 70% of the world natural dye production and 90% in Brazil. In the present work, annatto seeds were used of the species peruana paulista, which had nearly 2.1% of bixin. The process of dye extraction with ethyl alcohol showed 4% of dye in the form of powder with particle diameter of 28mm. The extraction process did not alter the chemical composition of the dye, which was confirmed by the electronic spectrum of absorption. Dyeings were carried out with different mordents to study the total colour difference as well as the wash fastness properties and friction fastness properties under wet and dry conditions. The samples treated with copper sulphate showed colour difference but at the same time showed better fastness results. The samples treated with resin (no formaldehyde) did not alter the colour significantly still better the fastness properties. From the results, it could be stated that the resin could be an alternative for heavy metallic mordents

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The study of a promising alternative for the treatment of produced water from the oil industry envisaging its reuse was the focus of this work. Millions of liters of water are generated per day, containing heavy metals in low concentrations (< 0,15 mg/L for Pb, <0,04 mg/L for Cd, <0,04 mg/L for Ni). The technology applied to extract these metals from aqueous phase was the solvent extraction and the extratants used were vegetable oils originated from coconut oil. They can be used in natural form or as derivatives, known as MAC - Mixture of Carboxílics Acids. The determination of the heavy metal con¬centrations in a complex matrix was made by using the atomic absorption spectrometry technique (AAS). On the bench tests using synthetics aqueous solutions containing metals, vegetable oils showed no power to extract the metals studied. The extractant MAC was selective for the Pb> Cd> Ni, in the concentration of 8% in the same organic phase. In this condition, the lower efficiency of extraction obtained was 92% for the Pb, 69% for the Cd, in the range of pH ranging from 6 to 8. An experimental planning was conducted for continuous tests. The device used was called MDIF Misturador-Decantador à Inversão de Fases and the aqueous phase was produced water from Pólo Indutrial de Guamaré/RN . No correlation between the studied variables (concentration of metal, concentration of extratant and agitation in the mixing chamer) could be obtained, because of possible factors which occurred as: variation in the composition of the studied sample, phenomena of precipitation and complexation of metals in the reservoir of feed, solubility of extratant

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Polyurethanes are very versatile macromolecular materials that can be used in the form of powders, adhesives and elastomers. As a consequence, they constitute important subject for research as well as outstanding materials used in several manufacturing processes. In addition to the search for new polyurethanes, the kinetics control during its preparation is a very important topic, mainly if the polyurethane is obtained via bulk polymerization. The work in thesis was directed towards this subject, particularly the synthesis of polyurethanes based castor oil and isophorone diisocianate. As a first step castor oil characterized using the following analytical methods: iodine index, saponification index, refraction index, humidity content and infrared absorption spectroscopy (FTIR). As a second step, test specimens of these polyurethanes were obtained via bulk polymerization and were submitted to swelling experiments with different solvents. From these experiments, the Hildebrand parameter was determined for this material. Finally, bulk polymerization was carried out in a differential scanning calorimetry (DSC) equipment, using different heating rates, at two conditions: without catalyst and with dibutyltin dilaurate (DBTDL) as catalyst. The DSC curves were adjusted to a kinetic model, using the isoconversional method, indicating the autocatalytic effect characteristic of this class of polymerization reaction

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This work aims at studying the influence of the concentration of calcite, its grain size and sintering temperature to obtain porous coating formulations that meet the design specifications. The experiments involved the physical-chemical and mineralogical caracterization of the raw materials, and mechanical tests on specimens dried and sintered, performing a planning mixture and factorial experiment, using the response surface methodology. The ceramic bodies studied were prepared by dry process, characterized, placed in conformity by uniaxial pressing and sintered at temperatures of 940 º C, 1000ºC, 1060ºC, 1120°C and 1180°C using a fast-firing cycle. The crystalline phases formed during sintering at temperatures under study, revealed the presence of anorthite and wolastonite, and quartz-phase remaining. These phases were mainly responsible for the physical and mechanical properties of the sintered especimens. The results shown that as increases the participation of carbonate in the composition of ceramic bodies there is an increase of water absorption and a slight reduction in linear shrinkage for all sintering temperatures. As for the mechanical strength it was observed that it tended to decrease for sintering at temperatures between 940 ° C and 1060 ° C and to increase for sintering at temperatures above 1060 ° C occurring with greater intensity for compositions with higher content of calcite. The resistence decreased with increasing participation of quartz in all sintering temperatures. The decrease in grain size of calcite caused a slight increase in water absorption for formulation with the same concentration of carbonate, remaining virtually unchanged the results of linear shrinkage and mechanical strength. In conclusion, porous ceramic coating (BIII) can be obtained using high concentrations of calcite and keeping the properties required in technical standards and that the particle size of calcite can be used as tuning parameter for the properties of ceramic products.

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One of the waste generated during the drilling of oil wells are gravel which are impregnated of drilling fluid. This residue consists of highly toxic chemicals, including toxic metals. This study suggests an alternative process to the treatment of this waste, by incorporating it the form of raw material in the ceramic matrix , and by solidification and stabilize the metals present, Aluminum (Al), Iron (Fe), Manganese (Mn) and Zinc (Zn). The raw materials were characterized by the techniques of X ray fluorescence (FRX), X ray diffraction (DRX), laser granulometry (GL), thermogravimetry (TG) and differential thermal analysis (ADT). To evaluate the percentage of gravel effect the environmental and technological properties were obtained from formulations containing 0, 10 and 20 % by weight of gravel in the ceramic matrix. After sintering at temperatures 1080, 1120 and 1160 °C, the samples were tested for water absorption, the linear shrinkage firing, voltage of rupture and solubility. The results obtained showed that the stabilization by solidification, is a viable alternative to safe disposal of waste drilling. Ceramics products can be used in the manufacture of solid bricks

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The disposal of sewage sludge is a growing problem face up to management of sanitary sevices. Otherwise, because its making process characteristic, the Ceramic Industry can tolerate the presence of this wastes as raw material. This study has as object to confirm the use of the sewage sluge in the Ceramic Industry like a sustentable alternative for its disposal. Futhermore, this study quests to evaluate the maximum proportion for incorporation of sludge wich result in technically and enviromentally suitable bricks. For found this proportion, the research consisted of (1) making of bricks in full scale, adde up 0%, 5%,10%, 15%, 20%, 25%,30%, 35% e 40% sludge, with size 220x105x45 mm, hand-molded by rammer and baked by industrial kiln; and (2) tecnical and enviromental evaluation of this bricks, according to Brazilian norms. The raw material uses were two distinct clays come from Goianinha/RN and sewage comes from a septic system tank and pumped into tank vehicle, of Natal/RN. The technical evaluation allowed to conclude the addiotion of the sludge brings about signifcant lost of mass and the water absorption grew up according to increase of sludge: every sludge-amended clay bricks absorved more water than control group. Thus, the compressive strength was signicantly decreased because the increase of sludge: bricks with 5% sludge added lost 45% of strength achieved at control group; the bricks made with 10 and 20% lost almost 70% of bigger strength. With up to 25% sludge added to the bricks, the streght decreased over 90%. Concerning heavy metal leaching, the two maximum proportion wich have tecnical approval, it means bricks sludge added with 15 and 20%, can say there is no risk of enviromental contamination using those bricks. This way, in this work context, it can to conclude the maximum proportion atends the technical and enviromental criterion is 20%

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Sludge of Wastewater Treatment Plants (WTPs) disposal is a problem for any municipality, for this reason the amount of sludge production is now a key issue in selecting treatment methods. It is necessary to investigate new applications for this waste type, due to the restrictions imposed by the environmental organs. The raw materials used in the Red Ceramic, are generally very heterogeneous, for this reason, such materials can tolerate the presence of different types of wastes. In Rio Grande do Norte, the roof tiles production corresponds to 60,61% from the total of ceramic units produced. Due to the importance of the ceramic industry of roof tiles for the state, allied to the environmental problem of the sludge disposal, this work had for objective to verify the possibility of the incorporation of sewage sludge in ceramic body used for production of roof tiles. In the research, sludge originating from drying beds of WTP of the Central Campus from UFRN and clays originating from a ceramic industry from Goianinha/RN were used. The raw materials were characterized by techniques of: analysis of particles distribution by diffraction to laser; real density; consistence limits; chemical analysis by X-ray fluorescence; mineralogical analysis by X-ray diffraction; organic matter; and solids content. Five batches of roof tiles were manufactured in the approximate dosages of 2%, 4%, 6%, 8% and 10%. To evaluate the properties of each final product, tests of water absorption, impermeability, bending strength, leachability and solubility were accomplished. The roof tiles manufactured with sludge presented characteristics similar to the roof tiles without sludge in relation to the environmental risk. The results showed that it is possible to use approximately up to 4% of sludge in ceramic bodies for production of roof tiles. However, it is observed that the high amount of organic matter (71%) present in the sludge is shown as factor that limits the sludge incorporation in ceramic bodies, worsening the quality of the roof tiles. It is necessary the use of mixtures of different raw materials under point of view of the granulometry and of the other chemical and mineralogical properties for the obtaining of a satisfactory mass to the production of ceramic roof tiles

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In this work we present a study of structural, electronic and optical properties, at ambient conditions, of CaSiO3, CaGeO3 and CaSnO3 crystals, all of them a member of Ca-perovskite class. To each one, we have performed density functional theory ab initio calculations within LDA and GGA approximations of the structural parameters, geometry optimization, unit cell volume, density, angles and interatomic length, band structure, carriers effective masses, total and partial density of states, dielectric function, refractive index, optical absorption, reflectivity, optical conductivity and loss function. A result comparative procedure was done between LDA and GGA calculations, a exception to CaSiO3 where only LDA calculation was performed, due high computational cost that its low symmetry crystalline structure imposed. The Ca-perovskite bibliography have shown the absence of electronic structure calculations about this materials, justifying the present work

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The physical properties and the excitations spectrum in oxides and semiconductors materials are presented in this work, whose the first part presents a study on the confinement of optical phonons in artificial systems based on III-V nitrides, grown in periodic and quasiperiodic forms. The second part of this work describes the Ab initio calculations which were carried out to obtain the optoeletronic properties of Calcium Oxide (CaO) and Calcium Carbonate (CaCO3) crystals. For periodic and quasi-periodic superlattices, we present some dynamical properties related to confined optical phonons (bulk and surface), obtained through simple theories, such as the dielectric continuous model, and using techniques such as the transfer-matrix method. The localization character of confined optical phonon modes, the magnitude of the bands in the spectrum and the power laws of these structures are presented as functions of the generation number of sequence. The ab initio calculations have been carried out using the CASTEP software (Cambridge Total Sequential Energy Package), and they were based on ultrasoft-like pseudopotentials and Density Functional Theory (DFT). Two di®erent geometry optimizations have been e®ectuated for CaO crystals and CaCO3 polymorphs, according to LDA (local density approximation) and GGA (generalized gradient approximation) approaches, determining several properties, e. g. lattice parameters, bond length, electrons density, energy band structures, electrons density of states, e®ective masses and optical properties, such as dielectric constant, absorption, re°ectivity, conductivity and refractive index. Those results were employed to investigate the confinement of excitons in spherical Si@CaCO3 and CaCO3@SiO2 quantum dots and in calcium carbonate nanoparticles, and were also employed in investigations of the photoluminescence spectra of CaCO3 crystal

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The contamination of the waters resources for wastewater from industrial, agricultural, and domestic sources is a serious environment problem, compromising its use for human consumption and agriculture. The Extremoz-RN Lake is an important freshwater source for the supply of the city of Natal, supplying a population of approximately 160,000 habitants. This aquatic body is located near an industrial pole which can be a serious risk factor for quality of its waters. The objectives of this study were examined the genotoxicity of Extremoz Lake between September of 2006 and January of 2008, by a combination of the Allium micronucleus test, piscine micronucleus test and the comet assay in erythrocytes from peripheral blood of Oreochromis niloticus. Additionally, the level of eight different heavy metals was quantified through spectrometry of atomic absorption of flame. The Allium test did not detect increase in the frequencies of micronucleus in none of the analyzed periods, however a strong cytotoxic activity was demonstrated for decrease in mitotic index in the analyses carried in April and July of 2007. Negative results had been detected in the frequencies of micronucleus in O. niloticus. A statistic significant increase was observed in the levels of DNA damage in comet assay carried in July of 2007. The results of the chemical analysis had detected increase in the levels of cadmium, chromium, copper, nickel, lead and zinc in different periods. These results demonstrated an alteration of the water s quality of the Extremoz Lake caused for the contamination for heavy metals and increase of DNA strand breaks. The use of biomonitoring program of the heavy metal and other pollutants with genotoxic potential combinated with genotoxicity assays is recommends.

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Dans les premières décennies du XXème siècle, un groupe d intellectuels brésiliens a pris pour soi la mission de conduire la nation aux chemins du progrès, en réfléchissant sur les transformations des villes et, souvent, en proposant et en mettant en avant des actions et mesures qui dirigeraient la modernisation du pays. Dans ce contexte, la ville apparaissait comme un synonyme de progrès en opposition à la campagne, en donnant emphase à la construction du Brésil urbain. À Natal, celui-ci a été une période de sensible modification dans l espace urbain, en suivant les préceptes de l hygiénisme et de l esthétique racionaliste, qui ont orienté les réformes entreprises dans beaucoup de villes brésiliennes. Les élites politiques et socioéconomiques de la capitale du Rio Grande do Norte ont developpé le discours en faveur de la modernisation qui avait pour objectif de justifier les interventions dans la ville et l introduction de l infra-structure de services urbains, par exemple, les services d illumination et de transport, qui à partir de 1911, ont commencé à être stimulés par l électricité. Cette modernisation est matérialisée par de nouveaux équipements et services, par des espaces remodelés en accord avec la rationalité technique de l urbaniste, pour l utilisation de nouvelles sources d énergie (gaz, électricité), en plus de la croissance de la population résidente en ville. Cependant, nous ne pouvons pas oublier que la construction de la ville moderne est passée tant par des transformations physiques, matérielles, comme par l absorption de valeurs, symboles, gestes, vocabulaires, objets, adoptions de nouvelles normes de comportement et par la formation de nouvelles sensibilités sur l espace urbain et la vie en ville. De cette manière, les nouvelles normes technologiques, comme l électricité, ont rendu possible des transformations dans la structure matérielle de la ville et en vie urbaine dans ses plus divers aspects. Ce travail propose d analyser la relation entre énergie électrique et la vie urbaine à Natal entre 1911 et 1940, en prenant en compte, pour cela, les actions d intervention de l État sur l espace urbain et les perceptions d intellectuels face aux transformations urbaines dont ils étaient les témoins. À partir de cette analyse, nous cherchons à préciser les efforts gouvernementaux pour la manutention des services d électricité et conservation des équipements urbains; comprendre comment l utilisation d énergie électrique a aidé à produire de nouvelles situations quotidiennes et comment elle a été perçue, traduite en sentiments et perceptions fondées dans la cohabitation avec cette innovation technique. Les élites locales désiraient diffuser des habitudes considerées modernes, en construisant une identification avec la manière de vie urbaine, fortement inspirée dans la vie dans les villes Européennes et Américaines. L électricité a rendu possible des expériences et sensations qui allaient caractériser l habitant de la ville

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The Epidermoid Carcinoma (EC) is the most common lesions located in the region of the head and neck and, despite advances in treatment modalities, the prognosis is still poor. The malignant cells show an increase in glucose uptake, process mediated by glucose transporters (GLUTs). Increased expression of GLUT 1 and GLUT 3 is related to the aggressive behavior of this lesion. The aim of this study was to evaluate, through immunohistochemistry, the expression of GLUTs 1 and 3 in EC of the lower lip. The sample consisted of 40 cases of EC of the lower lip, of which 20 had regional lymph node metastasis and the remaining 20 with absence of metastasis. The percentages of immunostained cells in front of tumor invasion and in the center of tumor were evaluated. These results were related to the presence and absence of lymph node metastasis, TNM classification and histological grading. The percentage of cytoplasmic/membranous expression of GLUT 1 ranged from 77.35% to 100%, while for GLUT 3 this value ranged from 0.79% to 100%. As for nuclear staining for GLUT 1, this percentage ranged from 0 to 0.42%, however. GLUT 3 showed only one case with nuclear staining. Despite the significant expression of tumor cells related to the proteins studied, we observed no statistically significant relationship between the variables and the antibodies analyzed, regardless of the region evaluated. However, there was a moderate positive correlation between cytoplasmic/membranous immunoexpressions of GLUT 1 in invasion front and in the tumor center (r = 0.679, p <0.001). Similarly, moderate positive correlation was found between the nuclear immunoexpressions of GLUT 1 in the invasion front and in the tumor center (r = 0.547, p <0.001). For GLUT 3, was also observed a moderate statistically significant positive correlation between cytoplasmic/membranous expression in tumor invasion front and in tumor center (r = 0.589, p <0.001). We also observed that the immunoreactivity for GLUT 1 was higher than GLUT 3 expression in invasion front (p <0.001) and tumor center (p <0.001). From these results, this study suggests that tumor hypoxia is a remarkable characteristic of the EC of the lower lip and GLUT 1 may be primarily responsible for glucose uptake into the interior of the malignant cells

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A partir dos diagnósticos das vulnerabilidades da condição juvenil contemporânea, as Políticas Públicas de Juventude tem ganhado maior força e um lugar mais definido nas pautas das demandas e conquistas sociais. Faz-se necessário, então, direcionar atenção para estas Políticas Públicas, a fim de promover uma reflexão sobre como ocorre a execução destas junto ao seu público alvo. Esta dissertação centraliza sua análise no Projovem Adolescente (PJA), uma das modalidades Programa Nacional de Inclusão de Jovens PROJOVEM que se destina ao atendimento de jovens com específica faixa etária entre 15 a 17 anos, com caráter assistencial e socioeducativo. Desta forma, o objetivo geral deste estudo foi discutir as ações do Projovem Adolescente no que diz respeito ao processo socioeducativo, a partir da perspectiva dos adolescentes participantes da cidade de Natal/RN. E, especificamente, objetivou-se: investigar de que maneira os adolescentes avaliam as atividades das quais participam, considerando se suas expectativas coincidem com as propostas do serviço; averiguar a participação dos adolescentes na elaboração, execução e avaliação das ações socioeducativas do serviço; bem como compreender as motivações que contribuem para a inserção e permanência ou evasão dos adolescentes no PJA. Para tanto foram realizados três grupos focais com adolescentes participantes do Projovem Adolescente, em diferentes núcleos do serviço, no município de Natal/RN. Cada grupo focal contou com dois encontros, em que primeiramente foram debatidos aspectos da participação nas ações socioeducativas e, num segundo encontro foram realizadas oficinas de produção de fanzines. A análise qualitativa dos dados foi realizada a partir da perspectiva teórica do materialismo histórico-dialético, utilizando-se como método de análise o Método Comparativo Constante, baseado na Teoria Fundamentada, que busca compreender o significado do fenômeno sob a perspectiva dos participantes. Os resultados foram apresentados divididos em eixos de análise os quais versaram sobre: as concepções dos jovens sobre adolescência e juventude; e a participação nas ações socioeducativas do PJA, destacando-se as características positivas e negativas apontadas pelos participantes, a relação dos jovens com o trabalho e as possibilidades e contribuições do PJA em seus contextos de vida. Em vista da análise empreendida, é possível constatar que a concepção dos participantes sobre a própria vivência da adolescência e juventude se encontra marcada pela absorção de determinadas imagens socialmente atribuídas aos jovens, como a que considera a juventude enquanto etapa de preparação para o mundo adulto. A participação nas ações socioeducativas, por sua vez, foi, de uma maneira geral, avaliada positivamente pelos participantes, não obstante esta avaliação, os jovens apresentaram uma visão muito crítica sobre a execução do serviço no município de Natal, relatando conhecer bem as dificuldades de ordem da gestão, bem como as contradições e limitações nas ações do serviço. Compreende-se a perspectiva da inclusão social no contexto neoliberal em que são implementadas as políticas sociais, contudo acredita-se que dar voz aos jovens participantes contribuiu para proporcionar uma reflexão sobre o modo como as políticas sociais, através do Projovem Adolescente tem atingido seu público, considerando as questões e perspectivas apresentadas pelos jovens como ferramentas a serviço das juventudes na construção de políticas democráticas e efetivas