Materiais supercondutores HTS para arranjos de antenas e aplicação de PBG para micro-ondas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Aplicações de arranjos de antenas de microfita com patch supercondutor

This work has as main objective the study of arrays of microstrip antennas with superconductor rectangular patch. The phases and the radiation patterns are analyzed. A study of the main theories is presented that explain the microscopic and macroscopic phenomena of superconductivity. The BCS, London equations and the Two Fluid Model, are theories used in the applications of superconductors, at the microstrip antennas and antennas arrays. Phase Arrangements will be analyzed in linear and planar configurations. The arrangement factors of these configurations are obtained, and the phase criteria and the spacing between the elements, are examined in order to minimize losses in the superconductor, compared with normal conductors. The new rectangular patch antenna, consist of a superconducting material, with the critical temperature of 233 K, whose formula is Tl5Ba4Ca2Cu9Oy, is analyzed by the method of the Transverse nTransmission Line (TTL), developed by H. C. C. Fernandes, applied in the Fourier Transform Domain (FTD). The TTL is a full-wave method, which has committed to obtaining the electromagnetic fields in terms of the transverse components of the structure. The inclusion of superconducting patch is made using the complex resistive boundary condition, using the impedance of the superconductor in the Dyadic Green function, in the structure. Results are obtained from the resonance frequency depending on the parameters of the antenna using superconducting material, radiation patterns in E-Plane and H -Plane, the phased antennas array in linear and planar configurations, for different values of phase angles and different spacing between the elements

Estudo dos óxidos A2B2O7 e ABO3 a base de terras raras, para aplicações térmicas e catalíticas a altas temperaturas

Rare earth elements have recently been involved in a range of advanced technologies like microelectronics, membranes for catalytic conversion and applications in gas sensors. In the family of rare earth elements like cerium can play a key role in such industrial applications. However, the high cost of these materials and the control and efficiencies associated processes required for its use in advanced technologies, are a permanent obstacle to its industrial development. In present study was proposed the creation of phases based on rare earth elements that can be used because of its thermal behavior, ionic conduction and catalytic properties. This way were studied two types of structure (ABO3 and A2B2O7), the basis of rare earths, observing their transport properties of ionic and electronic, as well as their catalytic applications in the treatment of methane. For the process of obtaining the first structure, a new synthesis method based on the use of EDTA citrate mixture was used to develop a precursor, which undergone heat treatment at 950 ° C resulted in the development of submicron phase BaCeO3 powders. The catalytic activity of perovskite begins at 450 ° C to achieve complete conversion at 675 ° C, where at this temperature, the catalytic efficiency of the phase is maximum. The evolution of conductivity with temperature for the perovskite phase revealed a series of electrical changes strongly correlated with structural transitions known in the literature. Finally, we can establish a real correlation between the high catalytic activity observed around the temperature of 650 ° C and increasing the oxygen ionic conductivity. For the second structure, showed clearly that it is possible, through chemical processes optimized to separate the rare earth elements and synthesize a pyrochlore phase TR2Ce2O7 particular formula. This "extracted phase" can be obtained directly at low cost, based on complex systems made of natural minerals and tailings, such as monazite. Moreover, this method is applied to matters of "no cost", which is the case of waste, making a preparation method of phases useful for high technology applications

Uma sequencia didática para o ensino da resolução da equação do 2. grau : adequação para o uso com professores

The present study aims to check whether the use of activities mediated by the History of Mathematics can contribute to improve the understanding of resolution the 2nd degree equation for teachers and undergraduates that reproduce methods of solving such equations, uncritically, without domain of the justifications for their actions. For this, we adapted a didactic sequence with activities that aims to cause a rediscovery of resolutive formula of 2nd degree equation through the method known as cut and paste. Finally, we presented the activity module containing the didactic sequence used during the study, as suggestion for use in the classroom, by the math teacher

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

Veredas infinitas, Recepção italiana de Grandes sertões: veredas

L'obiettivo principale di questo lavoro è valutare le difficoltà di comprensione e di identificazione nella ricezione da parte della cultura italiana dell'opera Grande sertão: veredas, da quelle trovate, in modo pionieristico, dal traduttore italiano, a quelle che sono state percepite e indicate al momento della lettura dai critici, dagli accademici, dall'autore di questo lavoro e, soprattutto, dai lettori comuni, mostrando, allo stesso tempo, che i problemi avuti dagli italiani nella traduzione esistono, sotto certi aspetti, anche per i brasiliani urbani, poiché la dimensione linguistico-geografica presente nel romanzo è così peculiare, che perfino molti lettori di lingua portoghese ignorano il mondo plasmato dal linguaggio di Guimarães Rosa rivelando una esacerbazione della questione universale espressa nella formula "traduttori, traditori". Partendo da tutto ciò, abbiamo cercato di dimostrare che, sebbene la traduzione di Edoardo Bizzarri abbia raggiunto un eccellente risultato, l'opera rosiana, così come nella poesia e di più di qualsiasi altra narrativa, comporta, nel passaggio da un idioma all'altro, perdite irrimediabili, tanto relative all'armonia musicale e ritmica, quanto alla richezza semantica che si occulta nel testo originale

Agostinho e o ceticismo: um estudo da crítica agostiniana ao ceticismo em Contra Acadêmicos

The assent of the Truth: here's a formula that seems to have puzzled philosophers since antiquity. The possibility of apprehending truth was defended by some philosophers who have been called dogmatic, due to their haste to judge appearances as representations of reality, and refuted by those who chose to continue questioning rather than engage with his predicament. These thinkers were called skeptics. Among those who defended the consent of the truth, is highlighted by St. Augustine in this research, which aims to combat the widespread skepticism in the ancient doctrine of the Academy of Plato in his work Against Academicos. Thus, to conduct this research we ask: What are the main arguments made by St. Augustine against the scholarly skepticism? In order to address the problem identified, we propose to investigate the critical skepticism of St. Augustine, identifying and analyzing the main rebuttals he built. For this purpose, we conducted a survey of aspects of both the skepticism about the life and thought of St. Augustine about this doctrine

Estudo do comportamento térmico e da luminescência de filmes de quitosana com os íons Eu3+ e Tb3+

Films of chitosan with trivalent lanthanides ions Eu3+ and Tb3+ were respectively prepared in the ratio of 3:1 m/m (chitosan: lanthanide) and 6:1 m/m (chitosan: lanthanide). There were no formations of films in a ratio of 1:1 m/m (chitosan: lanthanides). The films of chitosan with the Tb3+ ion have the same transparent appearance than the pure chitosan films. The film of chitosan with Eu3+ ion has a muddy appearance. These films present good resistance to tear. The appearance of the compounds prepared in ratio 1:1m/m is a white powder. The films and compounds of chitosan were characterized by Elementary Analysis (CHN), Thermal Analysis (TG/DTG) and Spectroscopy of Luminescence. The CHN analysis was made only for compounds prepared in ratio 1:1m/m, suggesting that these compounds possess the formula QUILn.6H2O, where QUI = Chitosan and Ln = Lanthanide. The results of the curves TG/DTG indicated that there are strong interactions between Eu3+ or Tb3+ and chitosan, causing a lesser lost of mass in the films. The luminescence analysis showed that the films of chitosan with the ions Eu3+ and Tb3+ present emissions in the region of the visible one, with bands of the chitosan and of the Eu3+ ion. The luminescence analysis of the compounds of chitosan with the Eu3+ and Tb3+ ions suggest that the chitosan does not transfer into energy to the ions lanthanides, however the chemical neighborhood around of the ion lanthanides breaks the selection rules and, conseqüently the 4f-4f transitions of the lanthanide ions are observed

Estudo de titanatos nanoestruturados obtidos por tratamento hidrotérmico de óxido de titânio em meio alcalino

TiTanate NanoTubes (TTNT) were synthesized by hydrothermal alkali treatment of TiO2 anatase followed by repeated washings with distinct degrees of proton exchange. TTNT samples with different sodium contents were characterized, as synthesized and after heattreatment (200-800ºC), by X-ray diffraction, scanning and transmission electron microscopy, electron diffraction, thermal analysis, nitrogen adsorption and spectroscopic techniques like FTIR and UV-Vis diffuse reflectance. It was demonstrated that TTNTs consist of trititanate structure with general formula NaxH2−xTi3O7·nH2O, retaining interlayer water in its multiwalled structure. The removal of sodium reduces the amount of water and contracts the interlayer space leading, combined with other factors, to increased specific surface area and mesopore volume. TTNTs are mesoporous materials with two main contributions: pores smaller than 10 nm due to the inner volume of nanotubes and larger pores within 5-60 nm attributed to the interparticles space. Chemical composition and crystal structure of TTNTs do not depend on the average crystal size of the precursor TiO2-anatase, but this parameter affects significantly the morphology and textural properties of the nanostructured product. Such dependence has been rationalized using a dissolution-recrystallization mechanism, which takes into account the dissolution rate of the starting anatase and its influence on the relative rates of growth and curving of intermediate nanosheets. The thermal stability of TTNT is defined by the sodium content and in a lower extent by the crystallinity of the starting anatase. It has been demonstrated that after losing interlayer water within the range 100-200ºC, TTNT transforms, at least partially, into an intermediate hexatitanate NaxH2−xTi6O13 still retaining the nanotubular morphology. Further thermal transformation of the nanostructured tri- and hexatitanates occurs at higher or lower temperature and follows different routes depending on the sodium content in the structure. At high sodium load (water washed samples) they sinter and grow towards bigger crystals of Na2Ti3O7 and Na2Ti6O13 in the form of rods and ribbons. In contrast, protonated TTNTs evolve to nanotubes of TiO2(B), which easily convert to anatase nanorods above 400ºC. Besides hydroxyls and Lewis acidity typical of titanium oxides, TTNTs show a small contribution of protonic acidity capable of coordinating with pyridine at 150ºC, which is lost after calcination and conversion into anatase. The isoeletric point of TTNTs was measured within the range 2.5-4.0, indicating behavior of a weak acid. Despite displaying semiconductor characteristics exhibiting typical absorption in the UV-Vis spectrum with estimated bandgap energy slightly higher than that of its TiO2 precursor, TTNTs showed very low performance in the photocatalytic degradation of cationic and anionic dyes. It was concluded that the basic reason resides in its layered titanate structure, which in comparison with the TiO2 form would be more prone to the so undesired electron-hole pair recombination, thus inhibiting the photooxidation reactions. After calcination of the protonated TTNT into anatase nanorods, the photocatalytic activity improved but not to the same level as that exhibited by its precursor anatase

Síntese, caracterização de ferritas espinélio com propriedades magnéticas e absorvedoras de microondas

Were synthesized spinel-type ferrites with general formula Ni0,8Mg0.2-xMxFe2O4, where M represents the doping Mn, Co or Mn + Co simultaneously, x ranges for the values 0.02, 0.05 and 0.1. The value of x was divided by 2 in cases where M equals Mn and Co conjugates. We used the citrate precursor method and heat treatment to obtain the phases at 1100°C. The materials were characterized by XRD, TGA/ DTGA, SEM, MAV and reflectivity measurements by the method of waveguide. Powders to 350°C/3.5 h were crystalline and nanosized. According to the results this temperature all powders have a percentage of ferrite phase over 90%. The composition had the addition of Mn and Co simultaneously showed a higher percentage of secondary phase NiO, 5.8%. The TGA/DTGA curves indicate that this sample reached phase (s) crystalline (s) at lowest temperatures. The X-ray diffractograms of the samples calcined at 350°C and 1100°C were treated with the Rietveld refinament technique. The powders calcined at 1100 °C/3h in air show to be 100% except spinel phase composition with 0.02 doping. The micrographs show clusters of particles with sizes smaller than 1 μm in calcination temperature of 1100°C which agreed with the result of Rietveld refinement. In the compositions doped with Mn were higher values of magnetization (45.90 and 53.20 Am2/kg), which did not cause high microwave absorption. The theoretical calculation of magnetization (MT) was consistent with the results, considering that there was agreement between the increase of magnetization experimental and theoretical. It was observed that there was the interrelation of the final effect of absorption with the thickness of MARE, the composition of ferrimagnetic materials and in particular the specific values of frequency. The analysis shows that the reflectivity increases in the concentration of cobalt increased the frequency range and also for absorption 10.17 GHz and 84%, respectively. The best result of chemical homogeneity and the value of 2.96 x 10-2 tesla coercive field were crucial for high performance ferrite absorber with 0.1 cobalt. The Cobalt has high magnetocrystalline anisotropy, it is associated with an increased coercive field, Hc. Therefore, this property improves the results of reflectivity of spinel ferrites

Síntese e caracterização da ferrita de MnZn obtida pelo método dos citratos precursores

It was synthesized MnZn ferrite with general formulae Mn1-xZnxFe2O4 (mol%), 0,3 ≤ x ≤ 0,7 by using the citrate precursor method. The precursors decomposition was studied by thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTG), differential thermal analysis (DTA) and Fourier transform infrared (FTIR) of powder calcined at 350ºC/3,5h. X-ray diffraction pattern (XRD) of samples was done from 350 to 1200ºC/2h using various atmospheres. The power calcined at 350ºC/3,5h formed spinel phase. It is necessary atmosphere control to avoid secondary phase such as hematite. From 900 to 1200ºC was obtained 90,66 and 100% of MnZn spinel ferrite phase, respectively. Analysis by dispersive energy scanning (EDS) at 350ºC shows high Mn and Zn dispersion, indicating that the diffusion process was homogeneous. Semi-quantitative analysis by EDS verified that despite the atmosphere control during calcinations at high temperatures (< 800ºC) occurred ZnO evaporation causing stoichiometric deviation. Vibrating sample magnetometer (VSM) measures show soft ferrite material characteristics with Hc from 6,5 x 10-3 to 11,1 x 10-2 T. Saturation magnetization (Ms) and initial permeability (µi) of MnZn spinel phase obtained, respectively, from 14,3 to 83,8 Am2/kg and 14,1 to 62,7 (Am2/kg)T

Cultivo de algas marinhas como desenvolvimento de comunidades costeiras

In northeastern Brazil, the extraction of agar has increased considerably in recent decades mainly using macroalgae of the genus Gracilaria. The pressure of the harvest of seaweed of this genus has compromised the sustainability of this natural resource. Given the current framework of decline in production of algae in the state of Rio Grande do Norte, it is necessary the deployment of crops that will assist in the development of coastal areas. This research aimed to develop studies on growth, productivity, efficiency and quality of agar of G. birdiae so as to provide subsidies for crops on commercial scale. The study was carried out in dry and rainy periods using rafts of cultivation. Algal biomass and the physical and chemical parameters of water were measured every fifteen days. In laboratory, the resistance and quality of agar were analyzed. The relative growth rate (TCR) was determined by the formula: RGR = ln (final weight / weight initial). 100 / interval time of sampling. During the study, environmental factors as salinity and temperature remained relatively constant (around 35 PSU and 28°C, respectively). The mean values of biomass ranged around 1952.67 ± 576g in the rainy period and 1925.67 ± 450g in the dry period, and they presented no significant variations. The maximum value of growth (TCR) was recorded in the dry season (7.45%.day-1), with an average over the study of 4.35%.day-1. The yield of agar ranged from 22% to 15%, and its resistance ranged from 850 to 650g. cm². The average obtained for the two periods was approximately 750 g cm². These results demonstrate the great potential of Gracilaria birdiae for mariculture can be used as an sustainable activity for coastal communities

Classificação de técnicas e auxílio à navegação de busca com base em sua carga cognitiva, precisão e eficiência

Navigation, in both virtual and real environments, is the process of a deliberated movement to a specific place that is usually away from the origin point, and that cannot be perceived from it. Navigation aid techniques (TANs) have as their main objective help finding a path through a virtual environment to a desired location and, are widely used because they ease the navigation on these unknown environments. Tools like maps, GPS (Global Positioning System) or even oral instructions are real world examples of TAN usage. Most of the works which propose new TANs for virtual environments aim to analyze their impact in efficiency gain on navigation tasks from a known place to an unknown place. However, such papers tend to ignore the effect caused by a TAN usage over the route knowledge acquisition process, which is important on virtual to real training transfer, for example. Based on a user study, it was possible to confirm that TANs with different strategies affects the performance of search tasks differently and that the efficiency of the help provided by a TAN is not inversely related to the cognitive load of the technique’s aids. A technique classification formula was created. This formula utilizes three factors instead of only efficiency. The experiment’s data were applied to the formula and we obtained a better refinement of help level provided by TANs.

Avaliação da imagem corporal de mulheres submetidas à cirurgia oncológica mamária

Breast cancer is the second type of cancer that affects more women of reproductive age in Brazil. Surgical treatments include: conserving surgery or mastectomy. Aimed to evaluate body image of women undergoing breast cancer surgery, based on the scale Body Image After Breast Cancer Questionnaire. It is a descriptive, exploratory, transversal, with a quantitative approach. Data were collected in Norte-riograndense League Against Cancer, between the months from March to May 2015, after consideration of the Research Ethics Committee of that institution CAEE 35155714.1.0000.5293. The study population consisted of women undergoing breast onco-surgery. To calculate the sample considered the finite population, totaling 120 subjects, collected four guys the most. Data were analyzed by the software Statistical Package for Social Sciences version 20.0. The domain scores of the scale were evaluated using descriptive and inferential statistics. The surgical group mastectomy without reconstruction showed greater impairment of body image in the field "vulnerability", "Care for the body" and "transparency" in relation to other surgical types, and suggests susceptibility to cancer, body appearance and worry that disturb other. The Kruskal-Wallis test showed greater dissatisfaction with body image in the fields "body Stigma" and "transparency" to the radical neoplastic surgery over other surgical types. Dissatisfaction with body image and physical appearance was detected in this study in all six image fields present in scale, with emphasis on the "body Stigma" and "Transparency". This means that the body image disorder is formulated based on the perception of others about themselves and not by perception "self", which justifies the concern with appearance, with body and hide the consequences stemmed cancer. It is expected that the data obtained from the evaluation of body image presented in this study contribute to enable the assistance to oncocirurgiada woman breast integral, essential for the practice of Nursing.

Avaliação da imagem corporal de mulheres submetidas à cirurgia oncológica mamária

Breast cancer is the second type of cancer that affects more women of reproductive age in Brazil. Surgical treatments include: conserving surgery or mastectomy. Aimed to evaluate body image of women undergoing breast cancer surgery, based on the scale Body Image After Breast Cancer Questionnaire. It is a descriptive, exploratory, transversal, with a quantitative approach. Data were collected in Norte-riograndense League Against Cancer, between the months from March to May 2015, after consideration of the Research Ethics Committee of that institution CAEE 35155714.1.0000.5293. The study population consisted of women undergoing breast onco-surgery. To calculate the sample considered the finite population, totaling 120 subjects, collected four guys the most. Data were analyzed by the software Statistical Package for Social Sciences version 20.0. The domain scores of the scale were evaluated using descriptive and inferential statistics. The surgical group mastectomy without reconstruction showed greater impairment of body image in the field "vulnerability", "Care for the body" and "transparency" in relation to other surgical types, and suggests susceptibility to cancer, body appearance and worry that disturb other. The Kruskal-Wallis test showed greater dissatisfaction with body image in the fields "body Stigma" and "transparency" to the radical neoplastic surgery over other surgical types. Dissatisfaction with body image and physical appearance was detected in this study in all six image fields present in scale, with emphasis on the "body Stigma" and "Transparency". This means that the body image disorder is formulated based on the perception of others about themselves and not by perception "self", which justifies the concern with appearance, with body and hide the consequences stemmed cancer. It is expected that the data obtained from the evaluation of body image presented in this study contribute to enable the assistance to oncocirurgiada woman breast integral, essential for the practice of Nursing.