Caracterização elementar de ligas metálicas em implantes dentários

An ideal biomaterial for dental implants must have very high biocompatibility, which means that such materials should not provoke any serious adverse tissue response. Also, used metal alloys must have high fatigue resistance due the masticatory force and good corrosion resistance. These properties are rendered by using alpha and beta stabilizers, such as Al, V, Ni, Fe, Cr, Cu, Zn. Commercially pure titanium (TiCP) is used often for dental and orthopedic implants manufacturing. However, sometimes other alloys are employed and consequently it is essential to research the chemical elements present in those alloys that could bring prejudice for the health. Present work investigated TiCP metal alloys used for dental implant manufacturing and evaluated the presence of stabilizing elements within existing limits and standards for such materials. For alloy characterization and identification of stabilizing elements it was used EDXRF technique. This method allows to perform qualitative and quantitative analysis of the materials using the spectra of the characteristic X-rays emitted by the elements present in the metal samples. The experimental setup was based on two X- rays tubes (AMPTEK Mini X model with Ag and Au targets), a X-123SDD detector (AMPTEK) and a 0.5mm Cu collimator, developed due to the sample characteristics. The other experimental setup used as a complementary technique is composed of an X-ray tube with a Mo target, collimator 0.65mm and XFlash (SDD) detector - ARTAX 200 (BRUKER). Other method for elemental characterization by energy dispersive spectroscopy (EDS) applied in present work was based on Scanning Electron Microscopy (SEM) EVO® (Zeeis). This method also was used to evaluate the surface microstructure of the sample. The percentual of Ti obtained in the elementary characterization was among 93.35 ± 0.17% and 95.34 ± 0.19 %. These values are considered below the reference limit of 98.635% to 99.5% for TiCP, established by Association of metals centric materials engineers and scientists Society (ASM). The presence of elements Al and V in all samples also contributed to underpin the fact that are not TiCP implants. The values for Al vary between 6.3 ± 1.3% and 3.7 ± 2.0% and for V, between 0.26 ± 0.09% and 0.112 ± 0.048%. According to the American Society for Testing and Materials (ASTM), these elements should not be present in TiCP and in accordance with the National Institute of Standards and Technology (NIST), the presence of Al should be <0.01% and V should be of 0.009 ± 0.001%. Obtained results showed that implant materials are not exactly TiCP but, were manufactured using Ti-Al-V alloy, which contained Fe, Ni, Cu and Zn. The quantitative analysis and elementary characterization of experimental results shows that the best accuracy and precision were reached with X-Ray tube with Au target and collimator of 0.5 mm. Use of technique of EDS confirmed the results of EDXRF for Ti-Al-V alloy. Evaluating the surface microstructure by SEM of the implants, it was possible to infer that ten of the thirteen studied samples are contemporaneous, rough surface and three with machined surface.

Nanoestruturas multicomponentes de CoFe2O4/Ag visando aplicações biológicas

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

Calibration and simulations of SIXS-P's response to energetic particles

The Solar Intensity X-ray and particle Spectrometer (SIXS) on board BepiColombo's Mercury Planetary Orbiter (MPO) will study solar energetic particles moving towards Mercury and solar X-rays on the dayside of Mercury. The SIXS instrument consists of two detector sub-systems; X-ray detector SIXS-X and particle detector SIXS-P. The SIXS-P subdetector will detect solar energetic electrons and protons in a broad energy range using a particle telescope approach with five outer Si detectors around a central CsI(Tl) scintillator. The measurements made by the SIXS instrument are necessary for other instruments on board the spacecraft. SIXS data will be used to study the Solar X-ray corona, solar flares, solar energetic particles, the Hermean magnetosphere, and solar eruptions. The SIXS-P detector was calibrated by comparing experimental measurement data from the instrument with Geant4 simulation data. Calibration curves were produced for the different side detectors and the core scintillator for electrons and protons, respectively. The side detector energy response was found to be linear for both electrons and protons. The core scintillator energy response to protons was found to be non-linear. The core scintillator calibration for electrons was omitted due to insufficient experimental data. The electron and proton acceptance of the SIXS-P detector was determined with Geant4 simulations. Electron and proton energy channels are clean in the main energy range of the instrument. At higher energies, protons and electrons produce non-ideal response in the energy channels. Due to the limited bandwidth of the spacecraft's telemetry, the particle measurements made by SIXS-P have to be pre-processed in the data processing unit of the SIXS instrument. A lookup table was created for the pre-processing of data with Geant4 simulations, and the ability of the lookup table to provide spectral information from a simulated electron event was analysed. The lookup table produces clean electron and proton channels and is able to separate protons and electrons. Based on a simulated solar energetic electron event, the incident electron spectrum cannot be determined from channel particle counts with a standard analysis method.

Insights into the emission of the blazar 1ES 1011+496 through unprecedented broadband observations during 2011 and 2012

Context. 1ES 1011+496 (z = 0.212) was discovered in very high-energy (VHE, E >100 GeV) γ rays with MAGIC in 2007. The absence of simultaneous data at lower energies led to an incomplete characterization of the broadband spectral energy distribution (SED). Aims. We study the source properties and the emission mechanisms, probing whether a simple one-zone synchrotron self-Compton (SSC) scenario is able to explain the observed broadband spectrum. Methods. We analyzed data in the range from VHE to radio data from 2011 and 2012 collected by MAGIC, Fermi-LAT, Swift, KVA, OVRO, and Metsähovi in addition to optical polarimetry data and radio maps from the Liverpool Telescope and MOJAVE. Results. The VHE spectrum was fit with a simple power law with a photon index of 3.69 ± 0.22 and a flux above 150 GeV of (1.46±0.16)×10^(−11) ph cm^(−2) s^(−1) . The source 1ES 1011+496 was found to be in a generally quiescent state at all observed wavelengths, showing only moderate variability from radio to X-rays. A low degree of polarization of less than 10% was measured in optical, while some bright features polarized up to 60% were observed in the radio jet. A similar trend in the rotation of the electric vector position angle was found in optical and radio. The radio maps indicated a superluminal motion of 1.8 ± 0.4 c, which is the highest speed statistically significant measured so far in a high-frequency-peaked BL Lac. Conclusions. For the first time, the high-energy bump in the broadband SED of 1ES 1011+496 could be fully characterized from 0.1 GeV to 1 TeV, which permitted a more reliable interpretation within the one-zone SSC scenario. The polarimetry data suggest that at least part of the optical emission has its origin in some of the bright radio features, while the low polarization in optical might be due to the contribution of parts of the radio jet with different orientations of the magnetic field with respect to the optical emission.

Síntese, caracterização e cinética da decomposição térmica dos materiais cerâmicos PrMO3 (M = Ni ou Co)

In this work have been studied the preparation, characterization and kinetic study of decomposition of the polymerizing agent used in the synthesis under non-isothermal condition ceramics PrMO3 of general formula (M = Co and Ni). These materials were obtained starting from the respective metal nitrates, as a cations source, and making use of gelatin as polymerizing agent. The powders were calcined at temperatures of 500°C, 700°C and 900°C and characterized by X-ray Diffraction (XRD), Thermogravimetric Analysis (TG / DTG/ DTA), Infrared Spectroscopy (FTIR), Temperature Programmed Reduction (TPR) and Scanning Electron Microscopy (SEM). The perovskite phase was detected in all the X-rays patterns. In the infrared spectroscopy observed the oxide formation as the calcination temperature increases with the appearance of the band metal - oxygen. The images of SEM revealed uniform distribution for the PrCoO3 and particles agglomerated as consequence of particle size for PrNiO3. From the data of thermal analysis, the kinetics of decomposition of organic matter was employed using the kinetics methods called Model Free Kinetics and Flynn and Wall, in the heating ratios 10, 20 and 30° C.min-1 between room temperature and 700°C. Finally, been obtained the values of activation energy for the region of greatest decomposition of organic matter in samples that were determined by the degree of conversion (α)

Síntese e caracterização de óxidos de cério e cobalto obtidos por gel-combustão e Pechini aplicados às reações de oxidação de n-hexano

Oxide type spinel AB2O4 presents structure adjusted for application in the automobile industry. The spinel of cobalt has many practical applications had its excellent physical and chemical properties such as catalyst in hydrocarbon oxidation reaction. The CeO2 has been used in many of these processes because it assigns to a material with excellent thermal resistance and mechanics, high capacity of oxygen stockage (OSC) among others properties. This work deals with the synthesis, characterization and catalytic application of spinel of cobalt and CeO2 with fluorita structure, obtained for method of Pechini and method of Gel-Combustion. The process of Pechini, the puff was obtained at 300 ºC for 2 h in air. In the process of Gel-Combustion the approximately at 350 ºC material was prepared and burnt for Pyrolysis, both had been calcined at 500 ºC, 700 ºC, 900 ºC and 1050 ºC for 2 h in air. The materials of the calcinations had been characterized by TG/DTA, electronic microscopy of sweepings (MEV), spectroscopy of absorption in the infra-red ray (FTIR) and diffraction of X-rays (DRX). The obtained material reaches the phase oxide at 450 oC for Pechini method and 500 °C for combustion method. The samples were submitted catalytic reaction of n-hexane on superficies of materials. The reactor function in molar ration of 0, 85 mol.h-1.g-1 and temperature of system was 450 °C. The sample obtained for Pechini and support in alumine of superficial area of 178,63 m2.g-1 calcined at 700 ºC, give results of catalytic conversions of 39 % and the sample obtained for method of gel-combustion and support in alumina of 150 mesh calcined at 500 ºC result 13 % of conversion. Both method were selective specie C1

Heavy elements in chestnuts

Chestnut fruit (CasChestnuts, Castanea sativa, heavy elements, PIXEtanea sativa Miller) are an important food resource in several countries. Portugal is the third largest European producer, with an average production of 25 thousand tons [1], being mainly produced in the North region of Trás-os-Montes. Earlier studies on chestnuts elemental composition were performed by atomic absorption to detect Ca, Mg, Na, K, Cu, Fe, Mn and Zn or by UV-VIS spectrophotometry to detect P [2-3]. In this work the elemental composition of two cultivars (Longal and Judia) of Castanea sativa Miller were studied by means of PIXE (Proton Induced X-ray Emission), using a broad proton beam at CTN-IST, Lisbon. Element identification (from Si to Pb) and quantification (following the method described in [4]) was done. Preliminary results show different composition according with the cultivar, not only in the major and minor elements (as it is described in the bibliography) but also in the trace elements, which includes the presence of Pb and other heavy elements. These preliminary results are part of a wider project that aims to evaluate chestnut fruits decontamination treatment with high energy electron beam and X-rays technology.

Síntese e caracterização de cerâmicas nanométricas para produção de gás de síntese

In this work, ceramic powders belonging to the system Nd2-xSrxNiO4 (x = 0, 0.4, 0.8, 1.2 and 1.6) were synthesized for their use as catalysts to syngas production partial. It was used a synthesis route, relatively new, which makes use of gelatin as organic precursor. The powders were analyzed at several temperatures in order to obtain the perovskite phase and characterized by several techniques such as thermal analysis, X-rays diffraction, Rietveld refinement method, specific surface area, scanning electron microscopy, energy dispersive spectroscopy of X-rays and temperature programmed reduction. The results obtained using these techniques confirmed the feasibility of the synthesis method employed to obtain nanosized particles. The powders were tested in differential catalytic conditions for dry reforming of methane (DRM) and partial oxidation of methane (POM), then, some systems were chosen for catalytic integrals test for (POM) indicating that the system Nd2-xSrxNiO4 for x = 0, 0.4 and 1.2 calcined at 900 °C exhibit catalytic activity on the investigated experimental conditions in this work without showing signs of deactivation

Desenvolvimento e caracterização de filtros cerâmicos para aplicações a altas temperaturas

Ceramic filters are cellular structures that can be produced by various techniques, among which we highlight the replication method, or method of polymeric sponge. This method consists of impregnating polymeric foam with ceramic slurry, followed by heat treatment, where will occur decomposition of organic material and the sinter of the ceramic material, resulting in a ceramic whose structure is a replica of the impregnated sponge. Ceramic filters have specific properties that make this type of material very versatile, used in various technological applications such as filters for molten metals and burners, make these materials attractive candidates for high temperature applications. In this work we studied the systems Al2O3-LZSA ceramic filters processed in the laboratory, and commercial Al2O3-SiC ceramics filters, both obtained by the replica method, this work proposes the thermal and mechanical characterization. The sponge used in the processing of filters made in the laboratory was characterized by thermogravimetric analysis. The ceramic filters were characterized by compressive strength, flexural strength at high temperatures, thermal shock, permeability and physical characterization (density and porosity) and microstructural (MEV and X-rays). From the results obtained, the analysis was made of the mechanical behavior of these materials, comparing the model proposed by Gibson and Ashby model and modified the effective area and the tension adjusted, where the modified model adapted itself better to the experimental results, representing better the mechanical behavior of ceramic filters obtained by the replica method

Estudo da adição de resíduo de scheelita em matriz cerâmica: formulação, propriedades físicas e microestrutura

Extractivism mineral is considered an activity highly degrading, due to the large volume of material that he moves in the form of ore and residues. The vast majority of mining companies do not show any technology or economically viable application that will allow the recycling of mineral residue, these being launched in areas receiving located the "open skies" degrade the environment. In Rio Grande do Norte to the production of ceramic red restricts their activities to the production of products such as: solid bricks, ceramic blocks, tiles, among others. Seeking to unite experiences and technical information that favor sustainable development, with important benefits to the construction sector and civil society in general, the present work studies the incorporation of the residue of scheelite in ceramic matrix kaolinitic, coming from the municipality of Boa Saúde - RN, in percentage of 5 %, 10 %, 20 %, 30% 40% and 50 %, by evaluating its microstructure, physical properties and formulation. The raw materials were characterized through the trials of X ray fluorescence, Diffraction of X rays, Differential Thermal Analysis and Termogravimetric Analysis. The samples were formed and fired at temperatures of 850o, 900o, 1000o, 1050o, 1100o, 1150o and 1200 oC, with isotherm of 1 hour and heating rate of 10 oC/min. Assays were performed technological of loss to fire, Water Absorption, Apparent Porosity, Apparent Density, Mass Loss in Fire and Bending Resistance; in addition to the Scanning Electron Microscopy, analyzing their physical and mechanical properties. The use of residue of scheelite in ceramic mass kaolinitic provided a final product with technological properties that meet the technical standards for the production of bricks and roofing tiles, with the percentage of 20% of waste that showed the best results

Avaliação da corrosão em dutos por técnica gravimétrica e de resistência elétrica

With the increasing of demand for natural gas and the consequent growth of the pipeline networks, besides the importance of transport and transfer of oil products by pipeline, and when it comes to product quality and integrity of the pipeline there is an important role regarding to the monitoring internal corrosion of the pipe. This study aims to assess corrosion in three pipeline that operate with different products, using gravimetric techniques and electrical resistance. Chemical analysis of residues originated in the pipeline helps to identify the mechanism corrosive process. The internal monitoring of the corrosion in the pipelines was carried out between 2009 and 2010 using coupon weight loss and electrical resistance probe. Physico-chemical techniques of diffraction and fluorescence X-rays were used to characterize the products of corrosion of the pipelines. The corrosion rate by weight loss was analyzed for every pipeline, only those ones that has revealed corrosive attack were analyzed located corrosion rate. The corrosion potential was classified as low to pipeline gas and ranged from low to severe for oil pipelines and the pipeline derivatives. Corrosion products were identified as iron carbonate, iron oxide and iron sulfide

Effects of spin on high-energy radiation from accreting black holes

Observations of jets in X-ray binaries show a correlation between radio power and black hole spin. This correlation, if confirmed, points toward the idea that relativistic jets may be powered by the rotational energy of black holes. In order to examine this further, we perform general relativistic radiative transport calculations on magnetically arrested accretion flows, which are known to produce powerful jets via the Blandfordâ Znajek (BZ) mechanism. We find that the X-ray and γ-ray emission strongly depend on spin and inclination angle. Surprisingly, the high-energy power does not show the same dependence on spin as the BZ jet power, but instead can be understood as a redshift effect. In particular, photons observed perpendicular to the spin axis suffer little net redshift until originating from close to the horizon. Such observers see deeper into the hot, dense, highly magnetized inner disk region. This effect is largest for rapidly rotating black holes due to a combination of frame dragging and decreasing horizon radius. While the X-ray emission is dominated by the near horizon region, the near-infrared (NIR) radiation originates at larger radii. Therefore, the ratio of X-ray to NIR power is an observational signature of black hole spin.

Chest Breadths to Predict Individuals' Age - A Case Based View

It is well known that rib cage dimensions depend on the gender and vary with the age of the individual. Under this setting it is therefore possible to assume that a computational approach to the problem may be thought out and, consequently, this work will focus on the development of an Artificial Intelligence grounded decision support system to predict individual’s age, based on such measurements. On the one hand, using some basic image processing techniques it were extracted such descriptions from chest X-rays (i.e., its maximum width and height). On the other hand, the computational framework was built on top of a Logic Programming Case Base approach to knowledge representation and reasoning, which caters for the handling of incomplete, unknown, or even contradictory information. Furthermore, clustering methods based on similarity analysis among cases were used to distinguish and aggregate collections of historical data in order to reduce the search space, therefore enhancing the cases retrieval and the overall computational process. The accuracy of the proposed model is satisfactory, close to 90%.

Caracterização material e microbiológica de espécimes fotográficos

Neste trabalho foram estudadas quatro espécies fotográficas, dois ambrótipos do séc. XIX e dois negativos de gelatina do séc. XX. Estas espécies são suscetiveis a degradações, físicas, químicas e microbiológicas. Técnicas de análise não destrutivas como, a fotografia, a microscopia ótica, a microscopia eletrónica de varrimento e espetroscopia de raios-X por dispersão em energias, a micro-espetroscopia de infravermelho em modo de reflexão total atenuada, a micro-espetroscopia de Raman e a micro-difração de raios-X foram utilizadas na caracterização material. A colonização microbiológica das amostras foi estudada através do isolamento e caracterização dos microrganismos contaminantes. Foram ainda realizados estudos de determinação de atividade celulolítica para os isolados fúngicos provenientes dos ambrótipos bem como ensaios de simulação, nos quais se utilizaram estes isolados para induzir contaminação em ambrótipos contemporâneos e assim avaliar o seu potencial biodeteriogénico. Foi ainda avaliado o potencial biodeteriogénico de isolados bacterianos em negativos de gelatina contemporâneos; Abstract: Material and microbiological characterization of photographic specimens This work presents a scientific study of four photographic specimens, two ambrotypes and two gelatin-silver negative plates from 19th and 20th century, respectively. These specimens are susceptible to physical, chemical and microbiological degradations. A non-destructive approach was used based on techniques such as technical photography, optical microscopy, scanning electron microscopy, infrared micro-spectroscopy, micro-Raman spectroscopy and X-rays micro-diffraction. Microbiological colonization of the samples was studied by isolation and characterization of the contaminating microorganisms. Studies to evaluate cellulolytic activity of fungal isolates from the ambrotypes were carried out and also simulation assays in which were used these isolated to induce contamination in contemporary ambrotypes were done to evaluate their biodeteriogenic potential. It was also studied the biodeteriogenic potential of the bacterial isolates from gelatin-silver negative plates which were subsequently inoculated in contemporary gelatin-silver negatives.

An Artificial Intelligence Approach to Individuals' Age Assessment

A link between patterns of pelvic growth and human life history is supported by the finding that, cross-culturally, variation in maturation rates of female pelvis are correlated with variation in ages of menarche and first reproduction, i.e., it is well known that the human dimensions of the pelvic bones depend on the gender and vary with the age. Indeed, one feature in which humans appear to be unique is the prolonged growth of the pelvis after the age of sexual maturity. Both the total superoinferior length and mediolateral breadth of the pelvis continues to grow markedly after puberty, and do not reach adult proportions until the late teens years. This continuation of growth is accomplished by relatively late fusion of the separate centers of ossification that form the bones of the pelvis. Hence, in this work we will focus on the development of an intelligent decision support system to predict individual’s age based on a pelvis' dimensions criteria. Some basic image processing techniques were applied in order to extract the relevant features from pelvic X-rays, being the computational framework built on top of a Logic Programming approach to Knowledge Representation and Reasoning that caters for the handling of incomplete, unknown, or even self-contradictory information, complemented with a Case Base approach to computing.