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In this work, a multifunctional system was developed in which antibacterial and luminescent properties were inserted into the matrix of hydroxyapatite (HAp) and its efficiency as a support for an antineoplastic drug was evaluated, aiming its application in the treatment of osseous diseases. The precipitation method was used for the synthesis of HAp, EuCl3 was used for the incorporation of Eu3+ as imaging agents, silver nanoparticles (AgNPs) with antimicrobial function were used, and a model of drug, 5-fluorouracil (5FU) was used. The developed material is characterized by several techniques, where crystalline peaks attributed to HAp were identified in the X-ray diffractogram, whereas the luminescence spectrum of the material presented emissions attributed to the Eu3+ ion. The identification and the uniform distribution of AgNPs, 5FU, and Eu3+ were confirmed by mapping the sample using energy-dispersive spectroscopy. The measurements indicated that 82% (±2.8) of 5FU was incorporated into the HAp matrix, and a gradual and increasing release of it as a function of time was observed. Assays carried out for different bacteria confirmed the antimicrobial action of the samples and the efficiency of the drug inserted into the matrix. An in vitro assay showed the bioactivity of the material and its potential to bind to living osseous tissue.

Laminar flame speeds of ammonia with oxygen-enriched air (oxygen content varying from 21 to 30 vol.%) and ammonia-hydrogen-air mixtures (fuel hydrogen content varying from 0 to 30 vol.%) at elevated pressure (1-10 bar) and temperature (298-473 K) were determined experimentally using a constant volume combustion chamber. Moreover, ammonia laminar flame speeds with helium as an inert were measured for the first time. Using these experimental data along with published ones, we have developed a newly compiled kinetic model for the prediction of the oxidation of ammonia and ammonia-hydrogen blends in freely propagating and burner stabilized premixed flames, as well as in shock tubes, rapid compression machines and a jet-stirred reactor. The reaction mechanism also considers the formation of nitrogen oxides, as well as the reduction of nitrogen oxides depending on the conditions of the surrounding gas phase. The experimental results from the present work and the literature are interpreted with the help of the kinetic model derived here. The experiments show that increasing the initial temperature, fuel hydrogen content, or oxidizer oxygen content causes the laminar flame speed to increase, while it decreases when increasing the initial pressure. The proposed kinetic model predicts the same trends than experiments and a good agreement is found with measurements for a wide range of conditions. The model suggests that under rich conditions the N 2 H 2 formation path is favored compared to stoichiometric condition. The most important reactions under rich conditions are: NH 2 + NH = N 2 H 2 + H, NH 2 + NH 2 = N 2 H 2 + H 2 , N 2 H 2 + H = NNH + H 2 and N 2 H 2 + M = NNH + H + M. These reactions were also found to be among the most sensitive reactions for predicting the laminar flame speed for all the cases investigated.

Matrizes de hidroxiapatita (HAp) dopadas com os ions lantanideos Eu3+, Ce3+ e Gd3+, [Ca10-xLnx(PO4)6(OH)2], foram obtidas pelo metodo da precipitacao com o objetivo de estudar suas propriedades fotofisicas. A partir de analises de Microscopia Eletronica de Varredura observou-se que amostras dopadas com ions lantanideos (Ln3+) apresentaram similaridade com a morfologia da HAp pura, por outro lado nos difratogramas de Raios X a partir do refinamento Rietveld verificou-se que a matriz aparece como fase majoritaria (≈ 70%) enquanto (≈ 30%) de uma fase secundaria de tricalcio fosfato (TCP) foi conferida em funcao das diferentes dopagens. Isotermas de adsorcao obtidas pela tecnica BET indicaram que todos os materiais sintetizados sao classificados como mesoporosos. Os espectros de emissao dos materiais exibem bandas caracteristicas dos ions Ln3+ incorporados a estrutura da matriz em 573 nm (5D0→F0), 600 nm (5D0→F1), 628 nm (5D0→F2), e 698 nm (5D0→F4) para HAp/Eu, 337-360 nm (5d→4f) para HAp/Ce e em 425 nm para HAp/Gd. Palavras-chave: Hidroxiapatita; Composito; Luminescente; Biomaterial; Propriedades.

Porous bodies were produced using hydroxyapatite as a starting material, gypsum, high purity material, low cost and that can be molded into the desired shape. Also, beads of polystyrene polymer. The first step of this work was to produce porous gypsum blocks obtained by mixing gypsum, water and polystyrene. After drying, they were submerged in acetone solvent for solubilizing the polymer and pore formation. The porous hydroxyapatite was synthesized in a second stage, where the porous gypsum blocks were immersed in a solution of (NH4)2HPO4 0.5 mol L-1 to 100 ° C and pH 7.0-9.0 for 24 hours. From this method, it was possible to produce bodies single phase hydroxyapatite with a maximum porosity of 70 ± 3% and a compressive strength of 1.48 ± 0.17 MPa.

Hydroxyapatite (HA) is a bioceramic material with excellent biological properties. However, these properties are strongly dependent of its crystallinity degree, with high values of crystallinity associated to poor resorption rates and bioactivity. This work evaluates the properties of HA samples produced by two different free-forming conformation methods, CNC machining and 3D printing. In both cases, porous gypsum samples were produced and subsequently converted into HA in a reaction with di-ammonium hydrogen phosphate at 100°C and pH 8. A total conversion of the samples was achieved after 36h independently of the conformation method used. The microstructure, however, before and after the conversion is showed to be dependent on the method used. After conversion the machined samples achieved a maximum compressive strength of 3.5 MPaforporosities of circa 80%, while 3D printed samples achieved a tensile strength of 2.0MPa by porosities of 61%.

O gesso é um sulfato de cálcio hemihidratado com fórmula química CaSO4.0,5H2O, este é produzido em grande abundância na região do Araripe estado de Pernambuco e apresenta uma pureza que varia de 80 a 95%, sua aplicação baseia-se principalmente na construção civil e em um segundo plano observa-se sua utilização na odontologia, industria química, ortopedia etc. Frente à elevada qualidade da matéria prima em questão e ao baixo emprego do gesso em materiais e objetos de maior valor agregado, verificou-se a necessidade da caracterização desta matéria prima para um maior conhecimento de suas propriedades, sendo realizadas para tal, análises de FTIR, DRX, FRX, MEV com EDS acoplado, ensaios mecânicos de resistência à compressão e à flexão, cálculo da porosidade geométrica dos corpos sólidos, análise granulométrica das partículas e avaliação do tempo de pega da pasta. Este estudo tem a finalidade de conhecer detalhadamente suas características químicas, morfológicas e mecânicas, para que então posteriormente tais informações possam ser válidas para estudos referentes ao melhoramento de suas propriedades visando sua aplicação em novos produtos.

The composite materials using polyhydroxybutyrate as matrix and hydroxyapatite as reinforcement (PHB/HA) were produced by molding, using pressing at 100 MPa and 165 °C for 30 min. The amount of filler was varied from 0 to 20 wt% to evaluate the effect of the HA particles on mechanical properties and the bioactivity of the composites. The increase of the HA amount reduced the compressive strength of the composites nearly 20% while bending strength reduced nearly 30%. However, the bioactivity after 14 days immersion in SBF was improved with the increase of HA amount, with formation of apatite layer on the surface of the PHB/HA composite. Resumo Materiais compósitos com matriz de poli-hidroxibutirato e material de reforço de hidroxiapatita (PHB/HA) foram produzidos por moldagem a partir de prensagem em 100 MPa e 165 °C durante 30 min. A quantidade de reforço variou de 0 a 20% em massa para avaliar o efeito das partículas de HA nas propriedades mecânicas e na bioatividade dos compósitos. O aumento da quantidade de HA reduziu a resistência à compressão dos compósitos em aproximadamente 20%, enquanto a resistência à flexão diminuiu 30%. No entanto, a bioatividade após 14 dias de imersão em SBF foi melhorada com o aumento da quantidade de HA, sendo observada camada de apatita na superfície do compósito PHB/HA.

The transformation of the gypsum into hydroxyapatite allows added value to this raw material, because the ceramic obtained has a high commercial value in relation to gypsum, while the polymer adds biocompatibility and bioactivity properties to the biocomposite. Thus, hydroxyapatite/polyhydroxybutyrate composites were prepared from the gypsum/polyhydroxybutyrate, using a 10% mass ratio of the polymer. The material was obtained by means of a chemical conversion carried out in a solution of ammonium hydrogen phosphate (0.5 mol.L-1) and alkaline medium (ammonium hydroxide 6.0 mol.L-1) for pH control. The reaction occurred at 100 °C at different test times. Analyzes of infrared spectroscopy showed functional groups characteristic of hydroxyapatite after 36 h of reaction; in addition, the biomaterial was identified as the major phase in X-ray diffraction patterns. Scanning electron microscopy of the materials before and after conversion showed a clear change in their morphologies, indicating the success of the synthesis. Resumo A transformação do gesso em hidroxiapatita permite agregar valor a essa matéria-prima, pois a cerâmica obtida possui alto valor comercial em relação ao gesso, enquanto o polímero acrescenta propriedades de biocompatibilidade e bioatividade ao biocompósito. Assim, compósitos de hidroxiapatita/poli-hidroxibutirato foram preparados a partir do gesso/poli-hidroxibutirato, usando uma proporção em massa de 10% do polímero. O material foi obtido por meio de uma conversão química realizada em solução de hidrogenofosfato de amônio (0,5 mol.L-1) e meio alcalino (hidróxido de amônio 6,0 mol.L-1) para controle de pH. A reação ocorreu a 100 °C em diferentes tempos de teste. Análises de espectroscopia no infravermelho mostraram grupos funcionais característicos de hidroxiapatita após 36 h de reação; além disso, o biomaterial foi identificado como a fase majoritária em difratogramas de raios X. Microscopia eletrônica de varredura dos materiais antes e após a conversão mostrou uma clara mudança em suas morfologias, indicando o sucesso da síntese.