Efeitos do tratamento superficial da sílica ativa com soluções de ácidos nítrico e fosfórico em propriedades do concreto

The addition of active silica potentially improves the quality of concrete due to its high reactivity and pore refinement effect. The reactivity of silica is likely related to its charge density. Variations in surface charge alter the reactivity of the material consequently affecting the properties of concrete. The present study aimed at investigating variations in the charge density of silica as a function of acid treatments using nitric or phosphoric acid and different pH values (2.0, 4.0 and 6.0). Effects on concrete properties including slump, mechanical strength, permeability and chloride corrosion were evaluated. To that end, a statistical analysis was carried out and empirical models that correlate studied parameters (pH, acid and cement) with concrete properties were established. The quality of the models was tested by variance analysis. The results revealed that the addition of silica was efficiency in improving the properties of concrete, especially the electrochemical parameters. The addition of silica treated using nitric acid at pH = 4.0 displayed the best cement performance including highest strength, reduced permeability and lowest corrosion current

Avaliação do efeito da adição de resíduo de borracha de pneu e brita calcária na formulação de compósitos cimentíceos

Researches have shown that the introduction of rubber in concrete improves the features of its deformability, as well as contributes to environmental disposal of waste generated in the tire retreading process. Furthermore, there is a high availability of limestone within RN and CE country. Ignorance about this stone, does not allow its wide use as aggregate, leaving, this abundant supply idle. A composite of limestone gravel, with proportions of tire rubber waste which could be used as concrete would be an alternative to concrete for low applications. Therefore, this research aims to evaluate the characteristics of concrete containing limestone gravel and proportions of little aggregate replacement (sand) by tire rubber waste. To this goal, the material components of the concrete were characterized, concrete specimens with limestone gravel were made, from the dash 1.0: 2.5: 3.5, varying the water/cement ratio, and inserting a commercial plasticizer, without a proportion of residue, known as reference. From this, concrete with and without the presence of the additive in the same proportions were chosen, as well as these with the use of granite gravel, for being the most used. Selected the references, to these, replacements of little aggregate (sand) were added replaced by rubber waste from the tire retreading process, treated with 1M NaOH in proportions from 5.0 to 20.0 % by mass, cured and exposed to the semiarid environment. The results indicate the possibility of using limestone gravel in the concrete composition with workability correction using plasticizer. There was a decrease in the mechanical properties of the concrete with increments of waste rubber, but there is an improvement in toughness and deformability of the composite, which makes it interesting for the construction of non-structural concrete floors, as well as, the rubber waste delayed the hardening process, continuing to gain resistance after 28 days

Plásticos reforçados a base de tecidos híbridos: efeitos da anisotropia e geometria normativa na caracterização mecânica e da fratura

As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy

Estudo de inibidores de corrosão em concreto armado, visando a melhoria na sua durabilidade

This thesis has as objective presents a methodology to evaluate the behavior of the corrosion inhibitors sodium nitrite, sodium dichromate and sodium molybdate, as well as your mixture, the corrosion process for the built-in steel in the reinforced concrete, through different techniques electrochemical, as well as the mechanical properties of that concrete non conventional. The addition of the inhibitors was studied in the concrete in the proportions from 0.5 to 3.5 % regarding the cement mass, isolated or in the mixture, with concrete mixture proportions of 1.0:1.5:2.5 (cement, fine aggregate and coarse aggregate), superplasticizers 2.0 % and 0.40 water/cement ratio. In the modified concrete resistance rehearsals they were accomplished to the compression, consistence and the absorption of water, while to analyze the built-in steel in the concrete the rehearsals of polarization curves they were made. They were also execute, rehearsals of corrosion potential and polarization resistance with intention of diagnose the beginning of the corrosion of the armors inserted in body-of-proof submitted to an accelerated exhibition in immersion cycle and drying to the air. It was concluded, that among the studied inhibitors sodium nitrite , in the proportion of 2.0 % in relation to the mass of the cement, presented the best capacity of protection of the steel through all the studied techniques and that the methodology and the monitoring techniques used in this work, they were shown appropriate to evaluate the behavior and the efficiency of the inhibitors

Aplicação da metodologia de planejamento de experimentos para formulação de massas cerâmicas para telhas

Rio Grande do Norte State stands out as one great producer of structural clay of the brazilian northeastern. The Valley Assu ceramic tiles production stands out obtained from ilitics ball clays that abound in the region under study. Ceramics formulation and the design of experiments with mixture approach, has been applied for researchers, come as an important aid to decrease the number of experiments necessary to the optimization. In this context, the objective of this work is to evaluate the effects of the formulation, temperature and heating rate in the physical-mechanical properties of the red ceramic body used for roofing tile fabrication of the Valley Assu, using design of mixture experiments. Four clays samples used in two ceramics industry of the region were use as raw material and characterized by X-ray diffraction, chemical composition, differential thermal analysis (DTA), thermogravimetric analysis (TGA), particle size distribution analysis and plasticity techniques. Afterwards, they were defined initial molded bodies and made specimens were then prepared by uniaxial pressing at 25 MPa before firing at 850, 950 and 1050 ºC in a laboratory furnace, with heating rate in the proportions of 5, 10 e 15 ºC/min. The following tecnologicals properties were evaluated: linear firing shrinkage, water absorption and flexural strength. Results show that the temperature 1050 ºC and heating rate of 5 ºC/min was the best condition, therefore presented significance in all physical-mechanical properties. The model was accepted as valid based of the production of three new formulations with fractions mass diferents of the initial molded bodies and heated with temperature at 1050 ºC and heating rate of 5 ºC/min. Considering the formulation, temperature and heating rate as variables of the equations, another model was suggested, where from the aplication of design of experiments with mixtures was possible to get a best formulation, whose experimental error is the minor in relation to the too much formulations

Estudo de Matérias-Primas do Rio Grande do Norte para Uso em Revestimento Poroso: Influência do teor de dolomita e temperatura de calcinação nas propriedades físico-mecânicas

The state of Rio Grande do Norte presents a great potentiality for the production of ceramic tiles because of having natural raw material in quantity and quality making its economical exploration possible, beyond the great energetic differential of the state, the natural gás. This works aims to study the influence of the dolomite and granulometry concentration and calcinations temperature in the obtaining of formulations for porous coverings which have to be coherent to the project,s specifications. The experiments have involved the physical-chemical and mineralogical characterizations of raw materials and mechanical tests in the dry and burnt proof bodies preceding a mixture experiment planning with the use of the response surface methodology, in order to get the best raw materials combinations to produce a ceramic mass with specific properties. The twelve ceramic masses studied in this work were prepared by the via dry process, characterized, shaped by uniaxial pressing and sinterized in the temperatures of 940ºC, 1000ºC, 1060ºC, 1120ºC and 1180ºC, using a fast burning cycle. The crystalline phases formed during the sintering in the temperatures in study have revealed the presence of anorthite and diopside beyond quartz with a remaining phase. These phases were the main responsible ones by the physical- mechanical properties of the sinterized proof bodies. The proof bodies after the sintering stage have presented water absorption higher than 10% and a good dimensional stability in all studied temperatures. However, the flexural breaking strength results in the temperatures of 940ºC, 1000ºC and 1060ºC, under the temperature zone of the vitrification of ceramic whiteware do not reach the flexural breaking strength specific for the porous wall tile (15 MPa), but in the temperature of 1120ºC next to the vitrification temperature zone, some whiteware ceramic (formulations) has reached the specified value for the porous wall tile. The results of this work have showed that the studied raw materials have great importance for used in the production of porous wall tiles (BIII)

Aproveitamento de resíduo de beneficiamento do caulim na produção de porcelanato cerâmico

Nowadays, industries from all sectors have great concerns over the disposition of the residues generated along the productive process. This is not different in the mineral sector, as this generates great volumes of residues. It was verified that the kaolin improvement industry generates great volumes of residue basically constituted of kaolinite, muscovite mica and quartz, which are basic constitution elements to formularisations of ceramics masses to the production of covering of stoneware tiles type. This happens because the methodology applied to the improvement process is still very rudimentary, what causes a very low yield, only ¼ from all the material volume that enters the improvement process, in the end, is marketable. The disposal of this residue, in a general way, causes a very big negative environmental impact, what has justified the researches efforts aiming to find a rational solution to this problem. In this way, the intention of this present work is the utilization of this residue in the manufacture of products to high quality ceramics covering, stoneware tiles in an industrial scale. For this purpose, the influence of the addition of the residue to a standard ceramics mass used by a ceramics sector company, already established in the market, with the intention of verifying the possibility of use of this residue as the mass complementary raw material and even the possible partial or total substitution of one of the components of the mass for the raw material in evidence will be studied. To the accomplishment of this work, the kaolin improvement residue generated by an industry of exploitation and improvement of kaolin, located in the region of Equador-RN, in the levels 1,2,4,8, 16 and 32% will be added to the standard mass already used for the production of stoneware tiles. The raw materials used, kaolin residue and the standard mass, were characterized through DRX, FRX, DTA, TGA and dilatometry. After the sintering of the bodies of test, tests of water absorption, apparent porosity, post burning linear retraction, apparent specific mass and flexural strength (3 point bending) were realized to determinate the technological properties of these materials. The results show the studied residue can be considered raw material of great potential to the industry of floor and ceramics covering of the stoneware tiles type

Atividade antiplasmódica e toxicológica de plantas medicinais usadas popularmente no Brasil : uma abordagem etnobotânica

Malaria is a disease of global distribution, recognized by governments around the world as a serious public health problem, affecting more than 109 countries and territories and endangering more than 3.3 billion people. The economic costs of this disease are also relevant: the African continent itself has malaria-related costs of about $ 12 billion annually. Nowadays, in addition to chloroquine, Plasmodium falciparum is resistant to many drugs used in the treatment of malaria, such as amodiaquine, mefloquine, quinine and sulfadoxine-pyrimethamine; resistance of Plasmodium vivax to treatments, although less studied, is also reported. Nature, in general, is responsible for the production of most known organic substances, and the plant kingdom is responsible for the most of the chemical diversity known and reported in the literature. Most medicinal plants commercialized in Brazil, however, are of exotic origin, which makes the search for endemic medicinal plants, besides a patent necessity, a fascinating subject of academic research and development. This study aimed to: (i) verify the antimalarial activity of ethanolic and hydroalcoholic extracts of Boerhavia paniculata Rich. And acetonic extract of Clethra scabra Pers. in Swiss albino mice infected by Plasmodium berghei NK65, (ii) observe possible combined effects between the course of infection by P. berghei NK65 and administration of these extracts in Swiss albino mice, and (iii) conduct a preliminary study of the acute toxicity of these extracts in Swiss albino mice. All extracts notable pharmacological activities - with parasite infections inhibitions ranging from 22% to 54%.These characteristics suggest that the activities are relevant, although comparatively lower than the activity displayed by the positive control group (always above 90%). The general framework of survival analysis demonstrates an overall reduction in survival times for all groups. Necroscopy has not pointed no change in color, shape, size and/or consistency in the evaluated organs - the only exception was the livers of rats submitted to treatment to hydroalcoholic extracts: these organs have been presented in a slightly congestive aspect with mass increasing roughly 28% higher than the other two groups and a p-value of 0.0365. The 250 mg/Kg ethanolic group has been pointed out by the Dunn s post test, as the only class with simultaneous inequalities (p<0.05) between positive and negative control groups. The extracts, notably ethanol extract, have, in fact, a vestigial antimalarial activity, although well below from the ones perceived to chloroquine-treated groups; nevertheless, the survival times of the animals fed with the extracts do not rise by presence of such therapy. Both the toxicopharmacological studies of the synergism between the clinical course of malaria and administration of extracts and the isolated evaluation of toxicity allow us to affirm the absence of toxicity of the extracts at the level of CNS and ANS, as well as their non-influence on food and water consumption patterns, until dosages of 500 mg/Kg. Necroscopic analysis leads us to deduct a possible hepatotoxic effect of hydroalcoholic extract at dosages of 500 mg/Kg, and an innocuous tissue activity of the ethanol extract, in the same dosage. We propose a continuation of the studies of these extracts, with protocol modifications capable of addressing more clearly and objectively their pharmacological and toxicological aspects

Avaliação do conhecimento e de habilidades clínicas em saúde sexual e reprodutiva na graduação de medicina

No Brasil, a despeito das conquistas obtidas a partir da implantação do Sistema Único de Saúde e dos avanços legais e institucionais na atenção a diversos problemas relacionados ao gênero, a incorporação de temas relacionados aos direitos humanos, sexuais e reprodutivos no contexto da formação profissional em saúde permanece deficiente. Este trabalho teve como objetivos avaliar a inserção da temática saúde sexual e reprodutiva no currículo do curso de graduação em Medicina, por meio do emprego de avaliações de conteúdo cognitivo, procedimental e atitudinal. Trata-se de estudo de intervenção educacional envolvendo alunos do internato do curso de Medicina da UFRN. Foram utilizados os seguintes métodos avaliativos: prova escrita, exame clínico objetivo estruturado (OSCE) e Mini-CEX. Como variáveis explicativas foram consideradas o sexo, idade e participação prévia no componente curricular optativo Saúde Reprodutiva . A avaliação do processo constou da aplicação de questionários de satisfação e entrevistas acerca dos métodos avaliativos utilizados. Considerando os três métodos avaliativos empregados, 183 estudantes participaram do estudo, com média de idade de 24,5 ± 2,2 anos, sendo 52,5% do sexo masculino e 47,5% do sexo feminino. No contexto geral, observamos concordância entre os desempenhos dos estudantes nas avaliações de conteúdo cognitivo, procedimental e atitudinal. A participação dos estudantes no componente curricular eletivo Saúde Reprodutiva mostrou-se associada com melhor desempenho em algumas dimensões da avaliação cognitiva e na avaliação com o Mini-CEX, em relação às competências de anamnese, profissionalismo e qualidades humanísticas, relação médico paciente e desempenho global. A análise da fidedignidade entre os avaliadores na avaliação com o método OSCE mostrou-se adequada (alfa de Cronbach superior a 70%) em relação ao desempenho global e aos aspectos técnicos das competências avaliadas, observando-se baixa confiabilidade na avaliação da comunicação médico-paciente. O presente trabalho constitui-se numa experiência educacional inovadora e pioneira no âmbito da educação médica brasileira no que tange à inserção da temática de saúde sexual e reprodutiva na graduação, sugerindo-se um impacto positivo da iniciativa na formação do médico generalista na UFRN. A avaliação de conhecimentos, habilidades e atitudes em saúde sexual e reprodutiva na graduação de Medicina mostrou-se factível, com alta concordância entre os diferentes métodos empregados. Os métodos OSCE e Mini-CEX podem ser aplicados ao contexto da saúde sexual e reprodutiva, possibilitando a avaliação de competências clínicas relevantes para a formação do médico generalista e que habitualmente não são contempladas nas avaliações rotineiramente realizadas na graduação

Desenpenho funcional, carga alostática e biomarcadores do estresse em idosos residentes na comunidade

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Candidíase vulvovaginal: sintomatologia, fatores de risco e colonização anal concomitante

Post-menarche patients with clinical signs of vulvovaginitis were analyzed in this study, whose aims were the following: identify the frequency of C. albicans and non C. albicans species and negative results, correlate the vaginal culture for yeast with risk factors and symptomatology; compare positive and negative results for yeast in the vaginal and anal cultures; compare the positive results for C. albicans with other results found in the vaginal and anal cultures; and compare concomitant positivity for C. albicans and non C. albicans in the vaginal and anal cultures. Sample selection occurred between May, 2003 and May, 2005, and included 99 patients from Natal, Brazil. The laboratory methods used consisted of CHROMagar Candida culture medium, thermotolerance test at 42-45°C and hypertonic NaCL, in addition to the classic methods of carbohydrate assimilation and fermentation. We used absolute numbers, percentages, means of central tendency, chi-squared test (χ2) with Yates correction, Fisher s exact test and odds ratio for statistical analysis. The most frequent species was C. albicans in 69% of the cases. The positivity for Candida spp showed an association with the use of tight-fitting intimate clothing and/or synthetics, allergic diseases and the occurrence of itching, leukorrhea and erythema. Anal colonization increased the likelihood of vaginal contamination by 2.8 and 4.9 times, respectively, for Candida spp and C. albicans. When compared to the other species, C. albicans-positive anal colonization increased by 3.7 times the likelihood of vaginal positivity. These data suggest likely vaginal contamination originating in the anus

Identificação e fatores de virulência de Candida spp isoladas da cavidade bucal de transplantados renais do hospital universitário Onofre Lopes em Natal-RN

Despite Candida species are often human commensals isolated from various oral sites such as: tongue, cheek and palatal mucosa plus subgingival region, there are some properties linked to the organism commonly known as virulence factors which confer them the ability to produce disease. Oral candidiasis is one of the main oral manifestations reported in literature related to kidney transplant patients. The objectives of the present study were to identify and investigate virulence factors of yeasts isolated from the oral cavity of kidney transplant recipients admitted at the Hospital Universitário Onofre Lopes, in Natal RN. Seventy Candida species isolated from 111 kidney transplant recipients were investigated in this study. Identification of the isolates was performed by using the evidence of germ tube formation, hypertonic broth, tolerance to grow at 42°C, micromorphology and biochemical profiles. We observed a high rate of isolation of yeasts from the oral cavity of kidney transplant recipients (63.1%) being C. albicans was the most prevalent species. Oral candidiasis was diagnosed in 14.4% of transplant recipients. We evaluated virulence properties of the isolates regarding to: biofilm formation on polystyrene microplates as well as XTT reduction, adherence to acrylic resin and human buccal epithelial cells and proteinase activity. Most isolates were able to form biofilm by the method of adhesion to polystyrene. All isolates of Candida spp. remained viable during biofilm formation when analyzed by the method of XTT reduction. The number of CFU attached to the acrylic resin suggested high adherence for C. parapsilosis. C. albicans isolates showed higher median adherence to human buccal epithelial cells than non-C. albicans Candida isolates. Nevertheless, this difference was not statistically significant. C. dubliniensis showed low ability to adhere to plastic and epithelial cells and biofilm formation. Proteolytic activity was observed for all the isolates investigated, including the unique isolate of C. dubliniensis. There was a statistically significant association between proteinase production and the presence of oral candidiasis. Studies related to oral candidiasis in renal transplant recipients are limited to clinical and epidemiological data, but investigations concerning Candida spp. virulence factor for this group of individuals are still scarce. We emphasize the importance of studies related to virulence factors of yeasts isolated from this population to contribute to the knowledge of microbiological aspects of oral candidiasis

Aspectos de patogenicidade e relacionamento genético de isolados clínicos vaginas e anais de Candida albicans oriundos de pacientes com candidíase vulvovaginal

Vulvovaginal candidiasis (VVC) is one of the most common causes of vaginitis and affects about 75% of women of reproductive age. The majority of cases (80 to 90%) are due to C. albicans, the most virulent species of the genus Candida. Virulence attributes are scarcely investigated and the source of infection remains uncertain. Objective: This study aimed to evaluate the virulence factors and genotypes of clinical isolates of C. albicans sequentially obtained from the anus and vagina of patients with sporadic and recurrent VVC. Materials and methods: We analyzed 62 clinical isolates of C. albicans (36 vaginal and 26 anal strains). Direct examination of vaginal and anal samples and colony forming units (CFU) counts were performed. Yeasts were identified using the chromogenic media CHROMagar Candida® and by classical methodology, and phenotypically characterized regarding to virulence factors, including the ability to adhere to epithelial cells, proteinase activity, morphogenesis and biofilm formation. The genotypes of the strains were investigated with ABC genotyping, microsatellite genotyping with primer M13 and RAPD. Results: We found 100% agreement between direct examination and culture of vaginal samples. Filamentous forms were present in most of the samples of vaginal secretion, which presented CFU counts significantly higher than the samples of anal secretion. There was no statistically significant difference between virulence factors of infecting vaginal isolates and those presented by colonizing anal isolates; as well as for the comparison of the vaginal isolates from patients with different clinical conditions (sporadic or recurrent VVC). There was a decrease in the ability to adhere to HBEC, morphogenesis and biofilm formation of the vaginal isolates during the progress of infection. There was an association between the ability to express different virulence factors and the clinical manifestations presented by the patients. Genotype A was the most prevalent (93.6%), followed by genotype C (6.4%). We found maintenance of the same ABC genotype and greater prevalence of microevolution for the vaginal strains of C. albicans sequentially obtained. Vaginal and anal isolates of C. albicans obtained simultaneously from the same patient presented the same ABC genotype and high genetic relatedness. Conclusion: It is noteworthy that the proliferation of yeast and bud-to-hypha transition are important for the establishment of CVV. The expression of virulence factors is important for the pathogenesis of VVC, although it does not seem to be determinant in the transition from colonization to infection or to the installation of recurrent condition. Genotype A seems to be dominant over the others in both vaginal and anal isolates of patients with VVC. The most common scenario was microevolution of the strains of C. albicans in the vaginal environment. It is suggested that the anal reservoir constituted a possible source of vaginal infection, in most cases assessed

Família, aluno e professor: as forças tipológicas da educação básica na região metropolitana de Natal

This work was developed in the research line: "The habitus of study: builder of a new reality in the basic education of metropolitan area Natal" which is being developed with the support of CAPES by the Centre for Education. Acts, especially the problem of academic performance of students in basic education of the public in the Metropolitan Region of Natal (RMN). Thus, the aim of this paper is to construct a typology of students in the 9th year of basic education, attending the public schools (state or municipal) of MRN, 2009, and assess, according to these profiles, what personal characteristics student and their families: economic, social and cultural capital as well as teaching practices create environments capable of favoring a good educational development as measured by the performance obtained in the assessments in mathematics and English language. The data used were provided through the microdata Brazil Exam 2009 held by INEP. We used the methods Grade of Membership (GoM) for construction of profiles relevance of students according to the characteristics already mentioned. With these profiles was verified, which were effectively generating good performance in school curriculum components evaluated. The findings indicate that students belonging to the profile considered good environment, able to achieve better school performance both in Portuguese as in Mathematics, compared to the extreme profiles and adverse deficit

A envergadura constitucional da posse qualificada na desapropriação privada

The constitutionalisation of private relations is the central theme of this work. Approached him overcome the dichotomy between public and private, through functionalization to the constitutionalization of civil law. Research on the effectiveness of horizontal rights. Constitutional under the lens, we analyzed the tense relationship between possession and ownership desfuncionalizada functionalized. We realize that having qualified and gained autonomy, and mechanism of access to goods, in view of the status sheet minimum, and of accomplishment, materializing human dignity. Then, we investigated the expropriation of private ownership qualified as legislative intervention that ensures the enforcement of fundamental rights through the state-court. We face the legal, the constitutionality and the burden of this institute. Also operability that it gives the judge, the process of exercise, the object, issues related to the burden and assessment of damages, as well as the nature, timing and costs of transferring property. At the end, we point to the scarcity palace, as well as the need to repair lege ferenda. The methodological approach has been championed by legal dogmatics in its analytical aspect, as we explore concepts and correlate with our planning. In empirical connotation, we evaluated the normativity and applicability of our law courts. For the ultimate in normative vision, answers to the problems faced and perform the necessary propositions, based on the results from the conceptual and empirical analysis