Estudo térmico dos resíduos gerados da destilação atmosférica das misturas diesel/biodiesel de dendê

The growing world demand for energy supplied by fossil fuels, a major contributor to the emission of pollutants into the atmosphere and causing environmental problems, has been encouraging governments and international organizations to reflect and encourage the use of alternative renewable sources. Among these new possibilities deserves attention biodiesel, fuel cleaner and easy to reproduce. The study of new technologies involving that source is necessary. From this context, the paper aims at analyzing the thermal stability by thermogravimetric analysis, of the waste generated from atmospheric distillation of mixtures with ratios of 5, 10, 15 and 20% palm biodiesel in diesel with and without addition of BHT antioxidant. It was synthesized biodiesel through palm oil, via homogeneous catalysis in the presence of KOH, with and without the use of BHT and subsequently added to the diesel common indoor type (S1800) from a gas station BR. The diesel was already added with 5% biodiesel, and thus the proportions used for these blends were subtracted from the existing ratio in diesel fuel, resulting in the following proportions palm oil biodiesel: 0% (B5), 5% (B10), 10 % (B15) and 15% (B20). From atmospheric distillation analysis, performed in mixtures with and without BHT were collected residue generated by each sample and performed a thermal study from the thermogravimetric analysis at a heating rate of 10 °C.min-1, nitrogen atmosphere and heating to 600 ° C. According to the specifications of Resolution No. 7/2008 for biodiesel, it was found that the material was synthesized in accordance with the specifications. For mixtures, it was noted that the samples were in accordance with the ANP Resolution No. 42/2009. Given the TG / DTG curves of the samples of waste mixtures with and without BHT antioxidant was able to observe that they showed a single stage of thermal decomposition attributed to decomposition of heavy hydrocarbons and esters and other heavier constituents of the waste sample weighed. The thermal behavior of residues from atmospheric distillation of mixtures of diesel / biodiesel is very important to understand how this affects the proper functioning of the engine. A large amount of waste can generate a high content of particulate material, coke formation and carbonaceous deposits in engine valves, compromising their performance

Hidrocarbonetos alifáticos em sedimentos de fundo do estuário do Rio Potengi, grande Natal (RN): implicações ambientais

The Potengi river estuary is located in the region of Natal (RN, Brazil), comprising a population of approximately 1,000,000 inhabitants. Besides the dominant urban presence, the estuary has fragments of mangrove forest. The objective of this study is to determine the aliphatic hydrocarbons found in the bottom sediments of this estuary, identifying their levels, distribution and their possible origins through the diagnostic rates, indexes and results comparisons with the local anthropic and natural characteristics. The samples were obtained according to a plan that allowed sampling of the estuary up to 12 km upstream from it as mounth. 36 stations were selected, grouped into 12 cross sections through the course of the river and spaced on average by 1 km. Each section consisted of three stations: the right margin, the deepest point and the left margin. The hydrocarbon n-alkanes from C10 to C36, the isoprenoids pristane and phytane, the unresolved complex mixture (UCM) and the total resolved hydrocarbons were analyzed by gas chromatography. N-alkanes, pristane, phytane and UCM were detected only at some stations. In the other, the concentration was below the detection limit defined by the analytical method (0.1 mg / kg), preventing them from being analyzed to determine the origin of the material found. By using different parameters, the results show that the estuary receives both the input of petrogenic hydrocarbons, but also of biogenic hydrocarbons, featuring a mixture of sources and relatively impacted portions. Based on the characteristics and activities found in the region, it is possible to affirm that petrogenic sources related to oil products enter the estuary via urban runoff or boats traffic, boat washing and fueling. Turning to the biogenic source, the predominant origin was terrestrial, characterized by vascular plants, indicating contribution of mangrove vegetation. It was evident the presence of, at specific points in the estuary, hydrocarbon pollution, and, therefore is recommended the adoption of actions aimed at interrupting or, at least, mitigating the sources potentially capable of damp petrogenic hydrocarbons in the estuary studied.

Simulação de fluxo de fluidos em meios porosos desordenados uma análise de efeito de escala na estimativa da permeabilidade e do coeficiente de arrasto

The present study provides a methodology that gives a predictive character the computer simulations based on detailed models of the geometry of a porous medium. We using the software FLUENT to investigate the flow of a viscous Newtonian fluid through a random fractal medium which simplifies a two-dimensional disordered porous medium representing a petroleum reservoir. This fractal model is formed by obstacles of various sizes, whose size distribution function follows a power law where exponent is defined as the fractal dimension of fractionation Dff of the model characterizing the process of fragmentation these obstacles. They are randomly disposed in a rectangular channel. The modeling process incorporates modern concepts, scaling laws, to analyze the influence of heterogeneity found in the fields of the porosity and of the permeability in such a way as to characterize the medium in terms of their fractal properties. This procedure allows numerically analyze the measurements of permeability k and the drag coefficient Cd proposed relationships, like power law, for these properties on various modeling schemes. The purpose of this research is to study the variability provided by these heterogeneities where the velocity field and other details of viscous fluid dynamics are obtained by solving numerically the continuity and Navier-Stokes equations at pore level and observe how the fractal dimension of fractionation of the model can affect their hydrodynamic properties. This study were considered two classes of models, models with constant porosity, MPC, and models with varying porosity, MPV. The results have allowed us to find numerical relationship between the permeability, drag coefficient and the fractal dimension of fractionation of the medium. Based on these numerical results we have proposed scaling relations and algebraic expressions involving the relevant parameters of the phenomenon. In this study analytical equations were determined for Dff depending on the geometrical parameters of the models. We also found a relation between the permeability and the drag coefficient which is inversely proportional to one another. As for the difference in behavior it is most striking in the classes of models MPV. That is, the fact that the porosity vary in these models is an additional factor that plays a significant role in flow analysis. Finally, the results proved satisfactory and consistent, which demonstrates the effectiveness of the referred methodology for all applications analyzed in this study.

Modelagem do desempenho ambiental dos projetos de exploração e produção aplicando equações estruturais

A legislação ambiental e os principais agentes que se relacionam com a empresa se constituem em fatores exógenos que não podem ser negligenciados ao formular-se e avaliar-se a política ambiental corporativa. As influências exógenas e seus efeitos sobre a gestão ambiental e o gerenciamento de projetos de exploração e produção (E&P) e, por essa via, sobre o desempenho ambiental, foram objetos de estudo desta tese. Embora o desempenho ambiental seja um assunto relevante, a pesquisa sobre esse tema ainda é escassa. Tal carência desponta ainda mais acentuada quando se aborda o desempenho ambiental de projetos na indústria de petróleo e gás. O principal objetivo deste estudo foi avaliar a relação entre a legislação ambiental vigente, as ações de órgãos reguladores, fornecedores, empresas terceirizadas e comunidades locais e o desempenho ambiental dos projetos de E&P na indústria de petróleo e gás e, também, analisar os efeitos do sistema de gestão ambiental e o gerenciamento dos projetos sobre tal desempenho. Na fase abdutiva, foi conduzido um estudo de caso com abordagem qualitativa em uma grande empresa brasileira do setor de petróleo e gás, na fase dedutiva, foi realizada uma pesquisa survey explanatória de corte transversal com abordagem quantitativa, incluindo 113 projetos de E&P de cinco unidades executoras da empresa. Foi formulado um modelo conceitual, com cinco construtos e sete hipóteses de pesquisa, representativo dos efeitos de fatores externos sobre o desempenho ambiental dos projetos de E&P. Os dados foram tratados aplicando a Análise Fatorial Exploratória e a Modelagem de Equações Estruturais com aplicação dos softwares IBM® SPSS® Statistics 20.0 e IBM® SPSS® Amos 18.0. O modelo de equações estruturais foi reespecificado e estimado utilizando o método de Máxima Verossimilhança e o procedimento bootstrap com 2000 reamostragens, até alcançar adequados valores dos índices de ajustamento. O modelo mostrou boa aderência às evidências empíricas, representando uma teoria explicativa dos fatores que influenciam o desempenho ambiental dos projetos de E&P na empresa estudada. As estatísticas descritivas apontaram adequado desempenho dos projetos de E&P com relação aos efluentes descartados, volume de água reutilizada, redução de resíduos e práticas de reciclagem. Identificou-se que projetos de maior porte alcançam melhor desempenho ambiental em relação aos de menor tamanho. Não foram achadas diferenças significativas entre os desempenhos de projetos executados por unidades operacionais distintas. Os resultados da modelagem indicaram que nem a legislação ambiental, nem os agentes externos exercem influência significativa sobre a sistemática da gestão dos projetos de E&P. Os agentes externos atuam sobre a gestão ambiental da empresa exercitando capacidades colaborativas, obstrutivas e propositivas. A legislação ambiental é percebida como entrave ao desenvolvimento dos projetos ao longo de seu ciclo de vida, principalmente, pelas deficiências dos órgãos ambientais. Identificou-se que o sistema de gestão ambiental influencia diretamente o Programa de Desenvolvimento e Execução de Projetos de E&P, que, por sua vez, provoca efeitos diretos e indiretos sobre o desempenho ambiental. Finalmente, comprovou-se que o Sistema de Gestão Ambiental da empresa é determinante para o desempenho ambiental dos projetos de E&P, tanto pelos seus efeitos diretos, como pelos indiretos, estes últimos mediados pela sistemática de gestão dos projetos de E&P

Otimização evalidação de métodos analíticos para a determinação simultânea de tuberculostáticos (4-FDC) por CLAE/DAD e CLUE/ DAD

Tuberculosis is a serious disease, but curable in practically 100% of new cases, since complied the principles of modern chemotherapy. Isoniazid (ISN), Rifampicin (RIF), Pyrazinamide (PYR) and Chloride Ethambutol (ETA) are considered first line drugs in the treatment of tuberculosis, by combining the highest level of efficiency with acceptable degree of toxicity. Concerning USP 33 - NF28 (2010) the chromatography analysis to 3 of 4 drugs (ISN, PYR and RIF) last in average 15 minutes and 10 minutes more to obtain the 4th drug (ETA) using a column and mobile phase mixture different, becoming its industrial application unfavorable. Thus, many studies have being carried out to minimize this problem. An alternative would use the UFLC, which is based with the same principles of HPLC, however it uses stationary phases with particles smaller than 2 μm. Therefore, this study goals to develop and validate new analytical methods to determine simultaneously the drugs by HPLC/DAD and UFLC/DAD. For this, a analytical screening was carried out, which verified that is necessary a gradient of mobile phase system A (acetate buffer:methanol 94:6 v/v) and B (acetate buffer:acetonitrile 55:45 v/v). Furthermore, to the development and optimization of the method in HPLC and UFLC, with achievement of the values of system suitability into the criteria limits required for both techniques, the validations have began. Standard solutions and tablets test solutions were prepared and injected into HPLC and UFLC, containing 0.008 mg/mL ISN, 0.043 mg/mL PYR, 0.030 mg.mL-1 ETA and 0.016 mg/mL RIF. The validation of analytical methods for HPLC and UFLC was carried out with the determination of specificity/selectivity, analytical curve, linearity, precision, limits of detection and quantification, accuracy and robustness. The methods were adequate for determination of 4 drugs separately without interfered with the others. Precise, due to the fact of the methods demonstrated since with the days variation, besides the repeatability, the values were into the level required by the regular agency. Linear (R> 0,99), once the methods were capable to demonstrate results directly proportional to the concentration of the analyte sample, within of specified range. Accurate, once the methods were capable to present values of variation coefficient and recovery percentage into the required limits (98 to 102%). The methods showed LOD and LOQ very low showing the high sensitivity of the methods for the four drugs. The robustness of the methods were evaluate, facing the temperature and flow changes, where they showed robustness just with the preview conditions established of temperature and flow, abrupt changes may influence with the results of methods

Produção, acúmulo e decomposição da serrapilhadeira e repartição da precipitação pluviométrica por espécies da caatinga

This study aimed to establish patterns of dynamics of litter and redistribution of rainfall of Caatinga vegetation. Sampling was done monthly for twenty three months in four areas: degraded, successional primary stage, secondary stage and late stage. We installed 72 collectors of 1.0 mx 1.0 m, with nylon fabric background in three areas. Litter deposited was fractionated into leaves, twigs, reproductive structures and miscellaneous, dried and weighed. To assess the stock of accumulated litter we used metal frame with dimensions of 0.5 mx 0.5 m, thrown randomly and collected monthly, taken to the laboratory for oven drying and weighed. To evaluate the decomposition, 40g of litter were placed in nylon bags (litterbags) mesh 1 mm ², dimensions 20.0 x 20.0 cm, being distributed on the soil surface and removed monthly, cleaned, dried and weighed. To evaluate the contribution of rainfall we used interceptometers installed 1.0 m above the ground surface, distributed under the canopy of six species of the caatinga, which evaluated the stemflow through collecting system installed around the stems of these species. The deposition of litter in the primary stage was 2.631,26 kg ha-1; 3.144,89 kg ha-1 in the secondary stage; 3.144,89 kg ha-1 in the late stage. The fraction of leaves was the largest contributor to the formation of litter in three stages. The degraded area showed greater accumulation of litter and decomposition has been sluggish during the dry period. We conclude that occurred greater litterfall in later stages. The late successional stage showed faster decomposition of litter, the evidence that is a better use of litter in nutrient cycling processes and incorporation of organic matter to the soil. The time required to decompose 50 % of the litter in the later stages of succession was lower indicating greater speed of release and reuse of nutrients by the vegetation. The specie jurema preta with less leaf area and consists of leaflets, showed greater internal precipitation in rain events of greater magnitude. The stemflow was not influenced by DAP and basal area. The water lost by trapping represented the largest proportion of total rainfall in all species studied

Design de interfaces para aplicativo de smartphone como recurso auxiliar no acompanhamento clínico de pacientes fibromiálgicos

Este trabalho tem como objetivo o desenvolvimento de interfaces com o usuário para aplicativo móvel smartphones com intuito de contribuir para a eficiência das atividades de profissionais e pesquisadores da área de fisioterapia ao oferecer suporte ao acompanhamento clínico da dor no tratamento de pacientes fibromiálgicos. Utilizando a abordagem de Design Centrado no Usuário - DCU, foram realizadas entrevistas e uma investigação contextual para a identificação inicial dos problemas e necessidades dos usuários. Verificou-se que as atividades de monitoramento e acompanhamento das sessões do tratamento de pacientes fibromiálgicos são, tradicionalmente, realizadas por meio de manipulando de formulários e fichas em papel (registro das condições de saúde do paciente) e escalas de classificação da dor em formato impresso (apresentadas ao paciente para indicação de sua dor percebida para cada ponto pré-determinado do corpo). Os procedimentos envolvidos nestas atividades dificultam o gerenciamento do desempenho do tratamento, o que, segundo relatos, reflete no comprometimento dos pacientes na adesão e frequência as sessões. A partir da observação e do levantamento das necessidades desses profissionais diante de suas atividades, foi proposto um aplicativo para smartphone com a intenção de minimizar os problemas ocasionados pelo uso das ferramentas convencionais e de prover informações rápidas acerca dos dados coletados. Então, seguindo a abordagem do DCU foi elaborado um modelo conceitual durante a etapa de concepção de soluções, o qual guiou a criação dos protótipos. A avaliação das interfaces do protótipo foi realizada com o envolvimento dos usuários a partir da técnica de avaliação cooperativa. Seus resultados proporcionaram o refinamento das interfaces e o desenvolvimento de uma nova proposta do design das interfaces em protótipo de alta fidelidade, produzido para o ambiente Android. Assim, esse trabalho faz parte do processo de desenvolvimento de um produto de software personalizado com foco na concepção e avaliação das interfaces com o usuário. Por meio da metodologia aplicada, observaram-se indícios os quais sugerem que as interfaces propostas apresentaram-se como um recurso facilitador e capaz de contribuir para eficiência das atividades no acompanhamento do tratamento de pacientes fibromiálgicos

Análise de aspectos ergonômicos do colete tático - um estudo de caso na ROCAM-RN

This thesis aims to analyze the ergonomic and functional aspects of the motorcycle patrolmen tactical vest and make a contribution to improve their technical and tactical characteristics reconciling pleasantness function, improving working conditions of policeman. The start point of this case study was the following hypothesis : The start point of this case study was the following hypothesis: once the policemen prepare their own tactical vests with layouts created by them. So, if someone observes these layouts, s/he will have an understanding of use of those devices and artifacts questions both positive, and negative. This hypothesis was confirmed by the results, considering that it was possible to understand the use of the tactic vests by means of the Policemen s opinion on issues recognized by themselves. It was also possible to understand that users perform interventions, based on their own inventive or learned from the experience of other policemen

Uma proposta de ensino para o nível fundamental a partir das concepções sobre insetos

O presente trabalho consiste em uma investigação acerca das concepções de estudantes sobre o que é um inseto. Partiu-se do pressuposto de que os alunos expressam concepções errôneas no momento de identificar os representantes do táxon Insecta e que isso é consequência das experiências do cotidiano e de erros conceituais oriundos da formação escolar incorreta. Os objetivos deste trabalho foram investigar sobre concepções alternativas acerca dos insetos com alunos do ensino fundamental II e propor situações para promoção de uma aprendizagem mais ativa. Os dados para analise foram coletados em três turmas de escolas diferentes: uma escola em Nova Parnamirim, da rede privada, e duas da rede pública municipal de ensino: uma do município de Natal/RN e a outra do município de Parnamirim/RN. Utilizou-se como instrumento um questionário aplicado em duas fases. Na primeira etapa foram feitas três questões abertas e duas fechadas. Na segunda, aplicaram-se mais três questões. Nesta oportunidade foram apresentados aos alunos uma lista com imagens de insetos e animais considerados não insetos. Os resultados dos questionários mostraram que os alunos apresentaram na sua maioria, 62%, sentimentos negativos sobre os insetos, expressos por palavras depreciativas, entre elas: nojentos, feios, asquerosos, perigosos, sendo estes mais da metade dos alunos da amostra. Sentimentos positivos representaram 20%: fazem bem ao homem, Deus criou, são bons, são bonitos, e 18% apresentaram neutralidade nessas categorias. Outro resultado apresentado foi que 82% generalizaram os animais artrópodes como sendo insetos. Como forma de resolver problemas relacionados as concepções uma unidade didática foi aplicada em uma das escolas envolvidas na pesquisa, validando assim um instrumento pedagógico que incluiu atividade lúdica constituída de um jogo de tabuleiro proporcionador de uma vivência de aprendizagem focada em conceitos científicos sobre os insetos fáceis de serem apreendidos

Atividades estruturais de equações polinomiais numa abordagem histórica por meio de e-book

The present study investigates how the inter-relationship of the content of polynomial equations works with structured activities and with the history of mathematics through a sequence of activities presented in an e-book, so that the result of this research will proceed will result in a didactic and pedagogic proposal for the teaching of polynomial equations in a historical approach via the reported e-book. Therefore, we have considered in theoretical and methodological assumptions of the History of Mathematics, in structured activities and new technologies with an emphasis on e-book tool. We used as a methodological approach the qualitative research, as our research object adjusts to the objectives of this research mode. As methodological instruments, we used the e-book as a synthesis tool of the sequence of activities to be evaluated, while the questionnaires, semi-structured interviews and participant observation were designed to register and analyze the evaluation made by the research, participants in the structured activities. The processing and analysis of data collected though the questionnaires were organized, classified and quantified in summary tables to facilitate visualization, interpretation, understanding, and analysis of these data. As for participant observation was used to contribute to the qualitative analysis of the quantified data. The interviews were synthetically transcribed and qualitatively analyzed. The analysis ratified our research objectives and contributed to improve, approve and indicate the use of e-book for the teaching of polynomial equations. Thus, we consider that this educational product will bring significant contributions to the teaching of mathematical content, in Basic Education

Os artigos de Euler sobre os números amigáveis

Among the many methodological resources that the mathematics teacher can use in the classroom, we can cite the History of Mathematics which has contributed to the development of activities that promotes students curiosity about mathematics and its history. In this regard, the present dissertation aims to translate and analyze, mathematically and historically, the three works of Euler about amicable numbers that were writed during the Eighteenth century with the same title: De numeris amicabilibus. These works, despite being written in 1747 when Euler lived in Berlin, were published in different times and places. The first, published in 1747 in Nova Acta Eruditorum and which received the number E100 in the Eneström index, summarizes the historical context of amicable numbers, mentions the formula 2nxy & 2nz used by his precursors and presents a table containing thirty pairs of amicable numbers. The second work, E152, was published in 1750 in Opuscula varii argument. It is the result of a comprehensive review of Euler s research on amicable numbers which resulted in a catalog containing 61 pairs, a quantity which had never been achieved by any mathematician before Euler. Finally, the third work, E798, which was published in 1849 at the Opera postuma, was probably the first among the three works, to be written by Euler

Física do meio ambiente: desafios de uma disciplina focada na formação de habilidades gerais

A disciplina Física do Meio Ambiente (FMA) foi criada em 1976 no Departamento de Física Teórica e Experimental da UFRN e, atualmente, faz parte da estrutura curricular do curso de Licenciatura em Física da UFRN e é de caráter obrigatório. Tal caráter se justifica, dentre outros motivos, pelo fato de que esta disciplina representa uma boa oportunidade dos licenciandos estudarem de que forma a Física pode contribuir para a compreensão de fenômenos relativos ao nosso Meio Ambiente, sejam eles relacionados às atividades humanas ou aos fenômenos naturais propriamente ditos e que, de uma forma ou de outra, afeta a sociedade. O nosso trabalho de pesquisa teve como objetivo principal elaborar um novo programa de ensino para a disciplina de Física do Meio Ambiente adequado às necessidades da educação científica para o século XXI. A pesquisa foi conduzida inicialmente com um levantamento histórico da disciplina desde sua origem no Departamento de Física ate os dias atuais, analise dos Projetos Pedagógicos do curso de Licenciatura em Física da UFRN, revisão bibliográfica sobre as definições de competências e habilidades em um contexto de ensino e segundo o pensamento de vanguarda nesse campo de pesquisa, acompanhamento do curso durante um semestre através de aulas observacionais, aplicação de questionário para a coleta de dados e análise de alguns livros didáticos de Física do Ensino Médio. A partir do perfil ou modelo profissional para o licenciado em Física da UFRN definimos os objetivos gerais para a disciplina de FMA em termos de habilidades gerais relacionadas com as atividades que um futuro professor de Física irá desempenhar no seu dia a dia. O nosso programa de ensino foi pensado no sentido de introduzir conteúdos de didática específica ao longo da disciplina, isto é, familiarizar os professores em formação com investigação e inovação didáticas voltadas para o ensino de temas que envolvam a conexão entre Física e Meio Ambiente. Como resultado de nossa pesquisa foi proposto um novo Programa de Ensino para FMA que pode ser útil aos futuros professores desta disciplina e foi elaborado segundo uma metodologia de organização científica do processo ensino

Princípio da Indução Matemática no Ensino Médio

We developed this dissertation aiming its in the process of teaching and learning of the Principle of Mathematical Induction and we set our efforts so that the students of the first year of the high school can assimilate the content having the knowledge seen in the basic education as foreknowledge. With this, we seek to awake in the student the interest on proofs, showing how much it s needed in examples that involve contents that he is already seen

Análise de grafos aplicada a relatos de sonhos: ferramenta diagnóstica objetiva e diferencial para psicose esquizofrênica e bipolar

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Análise da expressão imuno-histoquímica da ciclofilina A, EMMPRIN e MMP-7 na doença periodontal

Periodontal disease is an infectious disease resulting from the immunoinflammatory response of the host to microorganisms present in the dental biofilm which causes tissue destruction. The objective of this study was to evaluate the immunohistochemical expression of cyclophilin A (CYPA), extracellular matrix metalloproteinase inducer (EMMPRIN) and matrix metalloproteinase 7 (MMP-7) in human specimens of clinically healthy gingiva (n=32), biofilm-induced gingivitis (n=28), and chronic periodontitis (n=30). Immunopositivity for CYPA, EMMPRIN and MMP-7 differed significantly between the three groups, with higher percentages of staining in chronic periodontitis specimens, followed by chronic gingivitis and healthy gingiva specimens (p < 0.001). Immunoexpression of CYPA and MMP-7 was higher in the intense inflammatory infiltrate observed mainly in cases of periodontitis. Analysis of possible correlations between the immunoexpression of EMMPRIN, MMP-7 and CYPA and between the expression of these proteins and clinical parameters (probing depth and clinical attachment loss) showed a positive correlation of CYPA expression with MMP-7 (r = 0.831; p < 0.001) and EMMPRIN (r = 0.289; p = 0.006). In addition, there was a significant positive correlation between probing depth and expression of MMP-7 (r = 0.726; p < 0.001), EMMPRIN (r = 0.345; p = 0.001), and CYPA (r = 0.803; p < 0.001). These results suggest that CYPA, EMMPRIN and MMP-7 are associated with the pathogenesis and progression of periodontal disease