Reactive sputter magnetron reactor for preparation of thin films and simultaneous in-situ structural study by X-ray diffraction.

Reactive Sputter Magnetron (RSM) is a widely used technique to thin films growing of compounds both, in research laboratories and in industrial processes. The nature of the deposited compound will depend then on the nature of the magnetron target and the nature of the ions generated in the plasma. One important aspect of the problem is the knowledge of the evolution of the film during the process of growing itself. In this work, we present the design, construction of a chamber to be installed in the Huber goniometer in the XRD2 line of LNLS in Campinas, which allows in situ growing kinetic studies of thin films.

Crystallization and preliminary X-ray diffraction analysis of selenophosphate synthetases from Trypanosoma brucei and Leishmania major

Selenophosphate synthetase (SPS) plays an indispensable role in selenium metabolism, being responsible for catalyzing the activation of selenide with adenosine 5'-triphosphate (ATP) to generate selenophosphate, the essential selenium donor for selenocysteine synthesis. Recombinant full-length Leishmania major SPS (LmSPS2) was recalcitrant to crystallization. Therefore, a limited proteolysis technique was used and a stable N-terminal truncated construct (ΔN-LmSPS2) yielded suitable crystals. The Trypanosoma brucei SPS orthologue (TbSPS2) was crystallized by the microbatch method using paraffin oil. X-ray diffraction data were collected to resolutions of 1.9 Å for ΔN-LmSPS2 and 3.4 Å for TbSPS2.

Desenvolvimento de hidroxiapatita contendo prata via precipitação e imersão: avaliação do efeito antimicrobiano

A utilização de substitutos ósseos para recuperação da função perdida é uma constante busca dentro da área médica. Por isso os biomateriais têm recebido uma atenção muito grande por parte da comunidade científica, dentre eles os materiais a base de fosfato de cálcio. A hidroxiapatita, Ca10 (PO4)6 (OH) 2, tem sido muito estudada, pois além de representar a constituição da massa dos ossos naturais e dentes em 30 a 70%, possui propriedades de bioatividade e osteocondutividade, favorecendo e auxiliando o crescimento do tecido ósseo. Em contrapartida, infecções bacterianas podem surgir após o implante ocasionando a perda da funcionalidade a curto e médio prazo. Várias alternativas estão sendo testadas, geralmente associadas ao uso de antibióticos convencionais incorporados aos biomateriais. Uma alternativa a tais antibióticos seria a utilização de metais que possuem propriedades antibacterianas. A prata (Ag) é conhecida como um metal bactericida e por isso ganhou lugar de destaque dentre os estudos como um aliado importante no controle das infecções pós-cirúrgicas. Este trabalho teve como objetivo sintetizar, caracterizar e avaliar o efeito antimicrobiano da adição de íons de prata em hidroxiapatita. Foram obtidos pós de hidroxiapatita contendo prata (HAAg), nas concentrações de 0,1M; 0,01M e 0,001M pelo método de precipitação em temperatura ambiente e por imersão do pó de hidroxiapatita em soluções aquosas. As fases cristalinas e os grupamentos iônicos foram analisados para cada condição por técnicas de difração de raios X (DRX) e espectroscopia no infravermelho (IV) respectivamente. As informações sobre a morfologia e identificação de elementos químicos foi realizado pela técnica de microscopia eletrônica de varredura com espectroscopia de energia dispersiva (MEV EDS). As avaliações antimicrobianas foram realizadas por ensaios qualitativos e quantitativos, o ensaio qualitativo utilizou o teste de halo de difusão em disco para Staphylococcus aureus e Escherichia coli e o ensaio quantitativo utilizou contagem de bactérias para as cepas de Staphylococcus aureus. Os resultados de DRX e IV indicaram que independentemente do método de obtenção da HAAg foi possível observar a presença de prata metálica caracterizada pelos picos em 2θ=38,1º e 44,3º nas amostras HAAg0,1Im, HAAg0,1Pr e HAAg0,01Pr. Observou-se também a presença de AgO, correspondente ao pico em 2θ=37,5º nas amostras de HAAg0,01Pr e HAAg0,001Pr. Nos espectros de IV estão presentes as bandas que caracterizam a fase HA, referentes aos grupamentos PO43-, OH- e CO32-. Analisados em conjunto os ensaios qualitativos e quantitativos, as amostras HAAg0,01Im e HAAg0,001Im sintetizadas por imersão indicaram os melhores resultados para o ensaio de disco difusão, por apresentarem formação de halo inibição do crescimento bacteriano para a bactéria S. aureus. Para os ensaios quantitativos as amostras obtidas por precipitação com concentrações 0,1M e 0,01M de prata apresentaram melhor resultado por inibirem o crescimento bacteriano para as cepas S. aureus.

Desfechos tardios de sobreviventes de ensaio clínico randomizado controlado (protocolo ARDSnet vs. Open Lung Approach para o manejo ventilatório da síndrome do desconforto respiratório agudo moderado-grave)

Apesar da utilização da ventilação mecânica protetora como estratégia para o tratamento da síndrome do desconforto respiratório agudo, ao menos um quarto dos pacientes com essa síndrome ainda apresentam redução na função pulmonar após 6 meses de seguimento. Não se sabe se esta redução está relacionada com a gravidade da síndrome ou associada com a forma de ventilar o paciente. Nosso objetivo neste trabalho foi avaliar a associação entre alterações funcionais e estruturais do pulmão com parâmetros de gravidade clínica e de ventilação mecânica. Foi realizada uma análise secundária dos dados obtidos em estudo randomizado e controlado que incluiu pacientes com síndrome do desconforto respiratório agudo moderada/grave, internados em seis unidades de terapia intensiva em um hospital terciário da cidade de São Paulo. Foram analisados dados de pacientes que tinham ao menos um teste de função pulmonar no seguimento. O teste funcional incluiu a medida da capacidade vital forçada, volumes pulmonares e a capacidade de difusão do monóxido de carbono após 1, 2 e 6 meses de seguimento. Foram considerados variáveis independentes o volume corrente, a pressão de distensão e a pressão positiva ao final da expiração (todos medidos após 24 horas da randomização) e um sistema de classificação de prognóstico (APACHE II), a relação PaO2/FIO2 e a complacência respiratória estática (todos medidos antes da randomização). Também foi realizada tomografia de alta resolução do tórax juntamente com os testes de função pulmonar, e posterior análise quantitativa das imagens. Na avaliação de 6 meses também foi realizado teste de caminhada de 6 minutos e um questionário de qualidade de vida (SF-36). Um total de 21 pacientes realizaram o teste de função pulmonar após 1 mês e 15 pacientes realizaram após 2 e 6 meses de seguimento. A capacidade vital forçada foi relacionada inversamente com a pressão de distensão na avaliação de 1, 2 e 6 meses (p < 0,01). A capacidade de difusão do monóxido de carbono relacionou-se inversamente com a pressão de distensão e com o APACHE II (ambos p < 0,01) na avaliação de 1 e 2 meses. Após 6 meses de seguimento, houve correlação inversa entre a pressão de distensão e a capacidade vital forçada independente do volume corrente, da pressão de platô e da complacência estática respiratória após ajustes (R2 = 0,51, p = 0,02). A pressão de distensão também se relacionou com o volume pulmonar total, a densidade pulmonar media e a porcentagem de volume pulmonar não aerado ou pobremente aerado medidos através da análise quantitativa da tomografia computadorizada de tórax realizada na avaliação de 6 meses. Também foi observada relação entre a qualidade de vida após 6 meses de seguimento e a pressão de distensão considerando o domínio estado geral de saúde. Nós concluímos que mesmo em pacientes ventilados com reduzido volume corrente e pressão de platô limitada, maiores valores de pressão de distensão relacionaram-se com menores valores de função pulmonar no seguimento de longo prazo

Avaliação de compatibilidade entre pasta de cimento e fluido de perfuração não-aquoso utilizados em poços petrolíferos

Compatibility testing between a drilling fluid and a cement slurry is one of the steps before an operation of cementing oil wells. This test allows us to evaluate the main effects that contamination of these two fluids may cause the technological properties of a cement paste. The interactions between cement paste and drilling fluid, because its different chemical compositions, may affect the cement hydration reactions, damaging the cementing operation. Thus, we carried out the study of the compatibility of non-aqueous drilling fluid and a cement slurry additives. The preparation procedures of the non-aqueous drilling fluid, the cement paste and completion of compatibility testing were performed as set out by the oil industry standards. In the compatibility test is evaluated rheological properties, thickening time, stability and compressive strength of cement pastes. We also conducted analyzes of scanning electron microscopy and X-ray diffraction of the mixture obtained by the compatibility test to determine the microstructural changes in cement pastes. The compatibility test showed no visual changes in the properties of the cement paste, as phase separation. However, after the addition of nonaqueous drilling fluid to cement slurry there was an increased amount of plastic viscosity, the yield point and gel strength. Among the major causative factors can include: chemical reaction of the components present in the non-aqueous drilling fluid as the primary emulsifier, wetting agent and paraffin oil, with the chemical constituents of the cement. There was a reduction in the compressive strength of the cement paste after mixing with this drilling fluid. Thickening test showed that the oil wetting agent and high salinity of the non-aqueous fluid have accelerating action of the handle of the cement paste time. The stability of the cement paste is impaired to the extent that there is increased contamination of the cement slurry with the nonaqueous fluid. The X-ray diffraction identified the formation of portlandite and calcium silicate in contaminated samples. The scanning electron microscopy confirmed the development of the identified structures in the X-ray diffraction and also found the presence of wells in the cured cement paste. The latter, formed by the emulsion stability of the drilling fluid in the cement paste, corroborate the reduction of mechanical strength. The oil wetting agent component of the non-aqueous drilling fluid, the modified cement hydration processes, mainly affecting the setting time.

Características estruturais e fotocatalíticas do compósito oxihidróxido de nióbio/vermiculita

The preparation of nanostructured materials using natural clays as support, has been studied in literature under the same are found in nature and consequently, have a low price. Generally, clays serve as supports for metal oxides by increasing the number of active sites present on the surface and can be applied for various purposes such as adsorption, catalysis and photocatalysis. Some of the materials that are currently highlighted are niobium compounds, in particular, its oxides, by its characteristics such as high acidity, rigidity, water insolubility, oxidative and photocatalytic properties. In this scenario, the study aimed preparing a composite material oxyhydroxide niobium (NbO2OH) / sodium vermiculite clay and evaluate its effectiveness with respect to the natural clay (V0) and NbO2OH. The composite was prepared by precipitation-deposition method and then characterized by X-ray diffraction, infrared spectroscopy (XRD), energy dispersive X-ray (EDS), thermal analysis (TG/DTG), scanning electron microscopy (SEM), N2 adsorption-desorption and investigation of distribution of load. The application of the material NbO2OH/V0 was divided in two steps: first through oxidation and adsorption methods, and second through photocatalytic activity using solar irradiation. Studies of adsorption, oxidation and photocatalytic oxidation monitored the percentage of color removal from the dye methylene blue (MB) by UV-Vis spectroscopy. The XRD showed a decrease in reflection d (001) clay after modification; the FTIR indicated the presence of both the clay when the oxyhydroxide niobium to present bands in 1003 cm-1 related to Si-O stretching bands and 800 cm-1 to the Nb-O stretching. The presence of niobium was also confirmed by EDS indicated that 17 % by mass amount of the metal. Thermal analysis showed thermal stability of the composite at 217 °C and micrographs showed that there was a decrease in particle size. The investigation of the surface charge of NbO2OH/V0 found that the material exhibits a heterogeneous surface with average low and high negative charges. Adsorption tests showed that the composite NbO2OH/V0 higher adsorption capacity to remove 56 % of AM, while the material removed from V0 only 13 % showed no NbO2OH and adsorptive capacity due to the formation of H-aggregates. The percent removal of dye color for the oxidation tests showed little difference from the adsorption, being 18 and 66 % removal of dye color for V0 and NbO2OH/V0 respectively. The NbO2OH/V0 material shows excellent photocatalytic activity managing to remove just 95,5 % in 180 minutes of the color of MB compared to 41,4 % and 82,2 % of V0 the NbO2OH, proving the formation of a new composite with distinct properties of its precursors.

Síntese e caracterização de PSFC (Pr0,5Sr0,5Fe1-xCuxO3-δ, sendo x=0,2 e x=0,4) para aplicação como catodo de células a combustível de óxido sólido

The PSFC (Pr0.5Sr0.5Fe1-xCuxO3-δ) is a new mixed oxide perovskite and has been studied and evaluated the cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs), mainly due to its good compatibility with the electrolyte (CGO) and its high ionic conductivity and electronic in intermediate temperature. In this work, PSFC powders with two different compositions (Pr0,5Sr0,5Fe0,8Cu0,2O3- PSFC5582 and Pr0,5Sr0,5Fe0,6Cu0,4O3-PSFC5564) were synthesized by the citrate method using a new route. The powders obtained were characterized by thermal analysis (Differential Scanning Calorimetry and Thermogravimetry), and the material calcined at 800, 900 and 1000 °C for 5h were analyzed by X-ray diffractometry (XRD), with the Rietveld refinement of the diffraction data and dilatometry. PSFC5582 composite films were obtained by screen printing of powder calcined at 1000 °C. The films were deposited on substrate ceria doped with gadolinia (CGO) and then sintered at 1050 °C for 2h. The electrochemical performance of the electrodes was evaluated by impedance spectroscopy and the interface electrode/electrolyte was observed by scanning electron microscopy (SEM). The specific resistance area (ASR) was 0.44 Ω.cm² at 800 °C, slightly lower than those reported in the literature for cathodes containing cobalt. The thermal expansion coefficients of both the PSFC compositions were obtained and varied between 13 and 15 x 10-6 °C-1 , in a temperature range of 200 to 650 °C, demonstrating the good thermal compatibility of cathodes with Ce0,9Gd0,1O1,95 electrolytes (CET = 12 x 10-6 °C).

Estudo da deposição de filmes finos de BaTi(1-X)Zr(X)O3 por meio de planejamento Box-Behnken

Ferroelectric ceramics with perovskite structure (ABO3) are widely used in solid state memories (FeRAM’s and DRAM's) as well as multilayered capacitors, especially as a thin films. When doped with zirconium ions, BaTiO3-based materials form a solid solution known as barium zirconate titanate (BaTi1-xZrxO3). Also called BZT, this material can undergo significant changes in their electrical properties for a small variation of zirconium content in the crystal lattice. The present work is the study of the effects of deposition parameters of BaTi0,75Zr0,25O3 thin films by spin-coating method on their morphology and physical properties, through an experimental design of the Box-Behnken type. The resin used in the process has been synthesized by the polymeric precursor method (Pechini) and subsequently split into three portions each of which has its viscosity adjusted to 10, 20 and 30 mPa∙s by means of a rotary viscometer. The resins were then deposited on Pt/Ti/SiO2/Si substrates by spin-coating method on 15 different combinations of viscosity, spin speed (3000, 5500 and 8000 rpm) and the number of deposited layers (5, 8 and 11 layers) and then calcined at 800 ° C for 1 h. The phase composition of the films was analyzed by X-ray diffraction (XRD) and indexed with the JCPDS 36-0019. Surface morphology and grain size were observed by atomic force microscopy (AFM) indicating uniform films and average grain size around 40 nm. Images of the cross section of the films were obtained by scanning electron microscopy field emission (SEM-FEG), indicating very uniform thicknesses ranging from 140-700 nm between samples. Capacitance measurements were performed at room temperature using an impedance analyzer. The films presented dielectric constant values of 55-305 at 100kHz and low dielectric loss. The design indicated no significant interaction effects between the deposition parameters on the thickness of the films. The response surface methodology enabled better observes the simultaneous effect of variables.

Determinação do estado fundamental de compostos antiferromagnéticos da série Tb(1-x)Y(x)RhIn(5): aproximação teórico experimental

We present the results of electrical resistivity, magnetic susceptibility, specific heat and x-ray absorption spectroscopy measurements in Tb1−xYxRhIn5 (x = 0.00, 0.15, 0.4.0, 0.50 e 0.70) single crystals. Tb1−xYxRhIn5 is an antiferromagnetic AFM compound with ordering temperature TN ≈ 46 K, the higher TN within the RRhIn5 serie (R : rare earth). We evaluate the physical properties evolution and the supression of the AFM state considering doping and Crystalline Electric Field (CEF) effects on magnetic exchange interaction between Tb3+ magnetic ions. CEF acts like a perturbation potential, breaking the (2J + 1) multiplet s degeneracy. Also, we studied linear-polarization-dependent soft x-ray absorption at Tb M4 and M5 edges to validate X-ray Absorption Spectroscopy as a complementary technique in determining the rare earth CEF ground state. Samples were grown by the indium excess flux and the experimental data (magnetic susceptibility and specific heat) were adjusted with a mean field model that takes account magnetic exchange interaction between first neighbors and CEF effects. XAS experiments were carried on Total Electron Yield mode at Laborat´onio Nacional de Luz S´ıncrotron, Campinas. We measured X-ray absorption at Tb M4,5 edges with incident polarized X-ray beam parallel and perpendicular to c-axis (E || c e E ⊥ c). The mean field model simulates the mean behavior of the whole system and, due to many independent parameters, gives a non unique CEF scheme. XAS is site- and elemental- specific technique and gained the scientific community s attention as complementary technique in determining CEF ground state in rare earth based compounds. In this work we wil discuss the non conclusive results of XAS technique in TbRhIn5 compounds.

Nanoestruturas multicomponentes de CoFe2O4/Ag visando aplicações biológicas

Dissertação (mestrado)—Universidade de Brasília, Instituto de Física, Programa de Pós-Graduação em Física, 2015.

Sinterização de Ce1-XEuXO2-(X/2) para aplicação como eletrólito sólido em células a combustível de temperaturas intermediárias

Given the environmental concern over global warming that occurs mainly by emission of CO2 from the combustion of petroleum, coal and natural gas research focused on alternative and clean energy generation has been intensified. Among these, the highlight the solid oxide fuel cell intermediate temperature (IT-SOFC). For application as electrolyte of the devices doped based CeO2 with rare earth ions (TR+ 3) have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500-800 ° C). In this work, studied the Ce1-xEuxO2-δ (x = 0,1, 0,2 and 0,3), solid solutions synthesized by the polymeric precursor method to be used as solid electrolyte. It was also studied the processing steps of these powders (milling, compaction and two step sintering) in order to obtain dense sintered pellets with reduced grain size and homogeneous microstructure. For this, the powders were characterized by thermal analysis, X-ray diffraction, particle size distribution and scanning electrons microscopy, since the sintered samples were characterized by dilatometry, scanning electrons microscopy, density and grain size measurements. By x-ray diffraction, it was verified the formation of the solid solution for all compositions. Crystallites in the nanometric scale were found for both sintering routes but the two step sintering presented significant reduction in the average grain size

Desenvolvimento de bloco de vedação com barita na composição de partida para blindagem de radiação X

This work main objective is to study the use of bricks in barium X-rays rooms in order to contribute to the optimization of shielding rooms diagnosis. The work was based on experimental measurements of X-ray attenuation (40 to 150 kV), using ceramic seal bearing the incorporation of barium sulfat (BaSO4). Different formulations were studied in three different firing temperatures and evaluated for incorporation in the ceramic body. The composition of 20% of barite processed at a temperature of 950 ° C showed better physical and mechanical properties, is considered the most suitable for the purpose of this work. Were produced bricks sealing composition formulated based on that presented the best technological features. These blocks were tested physically as a building material and wall protective barrier. Properties such as visual, deviation from the square, face flatness, water absorption and compressive strength were evaluated for all the blocks produced. The behavior of this material as attenuator for X-rays was investigated by experimental results which take into account mortar manufacturers barium through the different strains and compared with the reference material (Pb). The simulation results indicated that the ceramic block barium shows excellent properties of attenuation equivalence lead taking into account the energy used in diagnostic X-ray

Caracterização microestrutural e elétrica de La(FexNi1-x)O3 sintetizado pelo método da gelatina

The present work deals with the synthesis of materials with perovskite structure with the intention of using them as cathodes in fuel cells SOFC type. The perovskite type materials were obtained by chemical synthesis method, using gelatin as the substituent of citric acid and ethylene glycol, and polymerizing acting as chelating agent. The materials were characterized by X-ray diffraction, thermal analysis, spectroscopy Fourier transform infrared, scanning electron microscopy with EDS, surface area determination by the BET method and Term Reduction Program, TPR. The compounds were also characterized by electrical conductivity for the purpose of observing the possible application of this material as a cathode for fuel cells, solid oxide SOFC. The method using gelatin and polymerizing chelating agent for the preparation of materials with the perovskite structure allows the synthesis of crystalline materials and homogeneous. The results demonstrate that the route adopted to obtain materials were effective. The distorted perovskite structure have obtained the type orthorhombic and rhombohedral; important for fuel cell cathodes. The presentation material properties required of a candidate cathode materials for fuel cells. XRD analysis contacted by the distortion of the structures of the synthesized materials. The analyzes show that the electrical conductivity obtained materials have the potential to act as a cell to the cathode of solid oxide fuel, allowing to infer an order of values for the electrical conductivities of perovskites where LaFeO3 < LaNiO3 < LaNi0,5Fe0,5O3. It can be concluded that the activity of these perovskites is due to the presence of structural defects generated that depend on the method of synthesis and the subsequent heat treatment

Tratamento térmico do titânio e suas consequências sobre as propriedades físico-químicas e de biocompatibilidade

The titanium and titanium alloys are widely used as biomaterial in biomedical device and so research have been developed aiming to improve and/or better to understand interaction biomaterial/biological environment. The process for manufacturing of this titanium implants usually involves a series of thermal and mechanical processes which have consequence on the final product. The heat treatments are usually used to obtain different properties for each application. In order to understand the influence of these treatments on the biological response of the surface, it was done, in this work, different heat treatments in titanium and analyzed their influence on the morphology, adhesion and proliferation of the pre-osteoblastic cells (MC3T3-E1). For such heat-treated titanium disks were characterized by optical microscopy, contact angle, surface energy, roughness, microhardness, X-ray diffraction and scanning through the techniques (BSE, EDS and EBSD). For the analysis of biological response were tested by MTT proliferation, adhesion by crystal violet and β1 integrin expression by flow cytometry. It was found that the presence of a microstructure very orderly, defined by a chemical attack, cells tend to stretch in the same direction of orientation of the material microstructure. When this order does not happen, the most important factor influencing cell proliferation is the residual stress, indicated by the hardness of the material. This way the disks with the highest level state of residual stress also showed increased cell proliferation