Influência do uso de combustíveis alternativos na síntese por combustão via microondas para a produção de materiais cerâmicos com estrutura espinélio

The development and study of detectors sensitive to flammable combustible and toxic gases at low cost is a crucial technology challenge to enable marketable versions to the market in general. Solid state sensors are attractive for commercial purposes by the strength and lifetime, because it isn t consumed in the reaction with the gas. In parallel, the use of synthesis techniques more viable for the applicability on an industrial scale are more attractive to produce commercial products. In this context ceramics with spinel structure were obtained by microwave-assisted combustion for application to flammable fuel gas detectors. Additionally, alternatives organic-reducers were employed to study the influence of those in the synthesis process and the differences in performance and properties of the powders obtained. The organic- reducers were characterized by Thermogravimetry (TG) and Derivative Thermogravimetry (DTG). After synthesis, the samples were heat treated and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), analysis by specific area by BET Method and Scanning Electron Microscopy (SEM). Quantification of phases and structural parameters were carried through Rietveld method. The methodology was effective to obtain Ni-Mn mixed oxides. The fuels influenced in obtaining spinel phase and morphology of the samples, however samples calcined at 950 °C there is just the spinel phase in the material regardless of the organic-reducer. Therefore, differences in performance are expected in technological applications when sample equal in phase but with different morphologies are tested

Arranjo de antenas de microfita com substrato anisotrópico com patch supercondutor e aplicações em nanotecnologia

The main objective in this work is the analysis of resonance frequency microstrip structures with glass fiber and electromagnetic band gap (EBG/PBG) substrate and analysis of microstrip antennas with rectangular patch of superconductor of high critical temperature (HTS). In this work was used the superconductors YBCO (critical temperature of 90K), SnBaCaCuOy (critical temperature of 160K), and Sn5InCa2Ba4Cu10Oy (critical temperature of 212K) with results in Gigahertz and Terahertz. Was used microstrip antennas arrays planar and linear phase and linear phase planar with patch with superconductor. It presents a study of the major theories that explain superconductivity. In phase arrays were obtained the factors arrays for such configurations, and the criteria of phase and spacing between the elements compound in the array, which were examined in order to get a main lobe with high directivity and high gain. In the analysis we used the method of Transverse Transmission Line (TTL) used in domain of the Fourier Transform (FTD). The LTT is a full wave method, which obtains the electromagnetic field in terms of the components transverse of the structure. The addition of superconductive patch is made using the boundary condition resistive complex. Results are obtained resonance frequency as a function of the parameters of the antenna, radiation patterns of the E and H Planes, for the phase antenna arrays in linear and planar configurations, for different values of the phase and the spacing between elements

Calibração cega de receptores cinco-portas baseada em separação cega de fontes

The exponential growth in the applications of radio frequency (RF) is accompanied by great challenges as more efficient use of spectrum as in the design of new architectures for multi-standard receivers or software defined radio (SDR) . The key challenge in designing architecture of the software defined radio is the implementation of a wide-band receiver, reconfigurable, low cost, low power consumption, higher level of integration and flexibility. As a new solution of SDR design, a direct demodulator architecture, based on fiveport technology, or multi-port demodulator, has been proposed. However, the use of the five-port as a direct-conversion receiver requires an I/Q calibration (or regeneration) procedure in order to generate the in-phase (I) and quadrature (Q) components of the transmitted baseband signal. In this work, we propose to evaluate the performance of a blind calibration technique without additional knowledge about training or pilot sequences of the transmitted signal based on independent component analysis for the regeneration of I/Q five-port downconversion, by exploiting the information on the statistical properties of the three output signals

Estudo das propriedades termofísicas com variação da expansibilidade de compósito desenvolvido com matriz PUR-NOP e carga funcional de argilomineral

In this study were conducted experimental procedures for determination of variation of the expandability of rigid polyurethane foam (PUR) from a natural oil polyol (NOP), specifically the Castor oil plant, Ricinus communis, pure and additions of the vermiculite in phase dispersed in different percentage within a range from 0% to 20%, mass replacement. From the information acquired, were defined the parameters for production of bodies of test, plates obtained through controlled expansion, with the final volume fixed. Initially, the plates were subjected to thermal performance tests and evaluated the temperature profiles, to later be extracted samples duly prepared in accordance with the conditions required for each test. Was proceeded then the measurement of the coefficient of thermal conductivity, volumetric capacity heat and thermal diffusivity. The findings values were compared with the results obtained in the tests of thermal performance, contributing to validation of the same. Ultimately, it was investigated the influence that changes in physical-chemical structure of the material had exerted on the variation of thermophysical quantities through gas pycnometry, scanning electron microscopy (SEM) combined with energy dispersive X-ray fluorescence spectroscopy (EDXRF), infrared spectroscopy using Fourier transform (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Based on the results obtained was possible to demonstrate that all load percentage analyzed promoted an increase in the potential expansion (PE) of the resin. In production of the plates, the composites with density near at the free expansion presented high contraction during the cure, being the of higher density adopted as definitive standard. In the thermal performance tests, the heating and cooling curves of the different composites had presented symmetry and values very close for lines of the temperature. The results obtained for the thermophysical properties of composites, showed little difference in respect of pure foam. The percentage of open pores and irregularities in the morphology of the composites were proportionate to the increment of vermiculite. In the interaction between the matrix and dispersed phase, there were no chemical transformations in the region of interface and new compounds were not generated. The composites of PUR-NOP and vermiculite presented thermal insulating properties near the foam pure and percentage significantly less plastic in its composition, to the formulation with 10% of load

Determinação experimental e modelagem termodinâmica do ponto de turbidez de sistemas aquosos com tensoativos nonilfenolpolietoxilados

The nonionic surfactants are composed of substances whose molecules in solution, does not ionize. The solubility of these surfactants in water due to the presence of functional groups that have strong affinity for water. When these surfactants are heated is the formation of two liquid phases, evidenced by the phenomenon of turbidity. This study was aimed to determine the experimental temperature and turbidity nonilfenolpoliethoxyled subsequently perform a thermodynamic modeling, considering the models of Flory-Huggins and the empirical solid-liquid equilibrium (SLE). The method used for determining the turbidity point was the visual method (Inoue et al., 2008). The experimental methodology consisted of preparing synthetic solutions of 0,25%, 0,5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12,5%, 15%, 17% and 20% by weight of surfactant. The nonionic surfactants used according to their degree of ethoxylation (9.5, 10, 11, 12 and 13). During the experiments the solutions were homogenized and the bath temperature was gradually increased while the turbidity of the solution temperature was checked visually Inoue et al. (2003). These temperature data of turbidity were used to feed the models evaluated and obtain thermodynamic parameters for systems of surfactants nonilfenolpoliethoxyled. Then the models can be used in phase separation processes, facilitating the extraction of organic solvents, therefore serve as quantitative and qualitative parameters. It was observed that the solidliquid equilibrium model (ESL) was best represented the experimental data.

Aplicação de tensoativos não iônicos na recuperação de fluidos de perfuração poliméricos

The drilling fluid used to assist in the drilling operation of oil wells, accumulates solids inherent in the formation as it is circulated in the well, interfering in the fluid performance during operation. It is discarded after use. The disposal of these fluids causes one of the most difficult environmental problems in the world. This study aims to promote liquid phase separation of drilling fluids, which have circulated in oil wells, and enable this recovered liquid to formulate a new fluid. For this, non-ionic surfactants were used in order to select the best outcome in phase separation. Five real water-based drilling fluids were utilized, which were collected directly from the fields of drilling oil wells, classified as polymeric fluids. The methodology used consisted in combining the fluid with surfactant and then subjecting it to a process of centrifugation or decantation. The decantating tests were scheduled through experimental planning 23 and 32, using as variables the percentage (%) of surfactant utilized and the stirring time in minutes. The surfactants used were ethoxylated nonylphenol and lauryl alcohol ethoxylated with different degrees of ethoxylation. Phase separation was monitored first by tests of stability, and subsequently by the height of the interface in beakers of 100 mL. The results showed that from the surfactants studied, the lauryl alcohol ethoxylated with 3 ethoxylation units has been the most effective in the phase separation process of the drilling fluids tested. The statistical tool used was of great industrial value regarding the programming phase separation in drilling fluids. In conclusion, the liquid phase separated using surfactant can be reused for a new formulation of drilling fluid with similar properties of a new fluid, assuring its efficiency. And in the resulting analysis it is also suggested that the adsorption is the mechanism that leads the phase separation, with surfactant adsorbing in the active solids

Tecnologia mais limpa para produção de mel seco de cana e sua inclusão em rações de frangos de corte

This study analyzed the effects of adding dry sugar cane molasses (MSC) to the feed of broiler chickens, and determining the economic feasibility of use of this type of diet; 240 male Ross race broiler chickens, one day in age, were utilized in this study. The experimental desing was a completely randomized whit 6 treatments and 4 replications, in 24 portions of 10 birds per parcel. The treatments corresponded to 6 rations (T1-T6) in phase initial (1-21 days) and 6 rations (T1-T6) in phasem finish (22-42 days) characterized by substitution of corn meal in levels increase 0, 5, 10, 15, 20 e 25% by the molasse dried sugar-cane. The birds received water and free ration during the whole creation phase, being the iso-proteins and iso-calories rations. The variance analysis showed the 1 a 21 days significant differences for average gain weight (P<0,05), average consumption of ration (P<0,05) and average alimentary conversion (P<0,05) and the 22 a 42 days, the analysis of variance showed significant differences for gain in weight (P<0,01) and average alimentary conversion (P<0,05). There no difference significant on average consumption of ration (P>0,05) the 22 a 42 days of age. Results showed out that is possible to use molasse dried sugar-cane up to 8,3 % in broilers ration. It was concluded the level of 8,3 % of addition gave the best economical returns in the experimental conditions

Efeitos do treino em esteira na marcha com dupla tarefa de indivíduos com doença de Parkinson: ensaio clínico controlado randomizado

Background: The gait automaticity loss difficults realization of concurrent activities - Dual Task (DT). In these situations, individuals with Parkinson`s disease (PD) show a significant reduction in gait velocity and stride length, as strides variability and asymmetry increased, factors predisposing to falls. However, recent studies have shown that training involving DT may cause subsequent improvements in gait variables with DT in individuals with PD. The treadmill use was adopted by this study, by promoting greater regularity in step and enhance training. Objective:To investigate immediate effects of gait training associated with cognitive tasks on gait in individuals with PD. Methods: Twenty-two volunteers were randomly divided into two groups: control group (n = 11), who performed gait training on a treadmill for 20 minutes, and the experimental group (n = 11), who performed treadmill gait training for 20 minutes associated with cognitive tasks of verbal fluency, memory, and spatial planning. Participants were evaluated in phase on of antiparkinsonian medication as the demographic, clinical and anthropometric (identification form), cognitive status (Montreal Cognitive Assessment - MoCA), executive function (Frontal Assessment Battery), level of physical disability (Hoehn and Yahr Modified), motor and functional status (Unified Rating Scale for Parkinson`s Disease - UPDRS), and kinematics (Qualisys Motion Capture System). Results: There were not differences between groups, but both showed improvement after the intervention. The control group had an increase in velocity (p = 0.008), stride length (p = 0.04), step length (p = 0.02) and decreased double support time(p = 0.03). The experimental group showed an increase in speed (p = 0.002), stride length (p = 0.008), step length (p = 0.02) and cadence (p = 0.01), as well as a decrease in the width stride (p = 0.001) and total support time (p = 0.02). As the angular variables, the experimental group had a significant increase in the initial contact angle of ankle (p = 0.01). Conclusion: The gait training combined with cognitive activities didn`t provide significant improvements in gait variables with DT, but this study was the first to demonstrate that gait training on treadmill as simple task minimized the negative interference of DT in PD

As competições sociais em grupos de Callithrix jacchus (Callitrichidae, Primates) são influenciadas pelo parentesco e pela convivência?

The Callitrichidae family is characterized by flexibility in its mating system, being possible to find monogamous, polyandrid and polygynic groups. Its social organization and mating system can be defined by the interaction between ecological and demographic factors plus the degree of relatedness among the individuals in the population. The objective of this work was to demonstrate the influence of relatedness and coexistence on the establishment and maintenance of social relations between Callithrix jacchus adult males. Four pairs of related adult males (CP), 4 pairs with coexistence between the animals in the pair (CC) and 4 pairs with no relatedness (SP) were studied. The pairs in the group CC had been kept in the same cage for at least 8 months before the experiment and the pairs in the group SP were put together at the beginning of the study. Each animal was observed 3 times/week for 2 months, in 15 min. sessions, through focal time sampling with instantaneous record each minute. In the first month, only the pair of males was kept in the cage (Phase I) and in the second month, a female was introduced into the cage (Phase II). The affiliative, agonistic and sexual interactions were registered. Affiliative interactions showed similar frequencies for all groups in phases. There was also no significant difference in the agonistic interactions of the CP, CC and SP males in Pase I, even considering that group SP exhibited higher levels of agonism. In Phase II, there was a statistically significant increase comparing to the others. The results demonstrate that relatedness and coexistence are of great importance for maintaining reprodutive and social stability inside the group. Nonetheless, in this study, only one of the males in the pair had sexual interations with the females, except for 2 pairs. This was assured through mate guarding and agonism directed to the potencial competitor. The most probable mating system would be functional monogamy, where the males would present low levels of competition, if there is relatedness and coexistence among them; on the other hand, a strong competition if there is no relatedness between the individuals. Even so, a polyandric system would also have to be considered

Relações sociais de callithrix jacchus machos: competição ou cooperação?

The group Callithrichidae is characterized by the flexibility in its mating system. This fact generates questions about the mechanisms that Callithrix jacchus males reach the breeding position in a group and how they prevent the subordinates reproduction, since the competition apparently happens with less intensity when compared to the females. Studies have shown the importance of social interactions and kinship among individuals in the distribution of mating opportunities in a group. This work aimed to evaluate if dyads of Callithrix jacchus males acted socially different due to kinship. We observed the agonistic and affiliative behaviours made by the males when associated in dyads (Phase 1) and when these dyads received a female (Phase 2), which was introduced in the pair`s cage for 45 minutes. In the phase 2, we also accounted for the sexual interactions between males and female in each trio. We used 16 males, 8 related (brothers-R) and 8 nonrelated (NR), as well as 8 females. Each phase lasted 4 weeks, with 3 observations/week, during 15 min/male in phase 1 and 2. In the first phase, two pairs of R males had a contested dominance and the other two, just like in the NR males, had an uncontested dominance. The NR dominant males were more aggressive than the subordinates. With the female`s entrance in the cage, all male pairs began to have an uncontested dominance. The NR males aggression frequency rose along with the subordinates` submission. In the R males, the frequency of grooming and physical contact was higher than in the NR males. So, we conclude that the low levels of agonism presented by the R males, along with the higher tolerance shown amongst them, lead us to believe that kinship attenuate the competition among these males

Influência de fotoperíodo artificial no comportamento de um primata neotropical diurno (Callithrix jacchus)

One of the main environmental cues for the adjustment of temporal organization of the animals is the light-dark cycle (LD), which undergoes changes in phase duration throughout the seasons. Photoperiod signaling by melatonin in mammals allows behavioral changes along the year, as in the activity-rest cycle, in mood states and in cognitive performance. The aim of this study was to investigate if common marmoset (Callithrix jacchus) exhibits behavioral changes under short and long photoperiods in a 24h cycle, assessing their individual behaviors, vocal repertoire, exploratory activity (EA), recognition memory (RM) and the circadian rhythm of locomotor activity (CRA). Eight adult marmosets were exposed to a light-dark cycle of 12:12; LD 08:16; LD 12:12 and LD 16:08, sequentially, for four weeks in each condition. Locomotor activity was recorded 24h/day by passive infrared motion detectors above the individual cages. A video camera system was programmed to record each animal, twice a week, on the first two light hours. From the videos, frequency of behaviors was registered as anxiety-like, grooming, alert, hanging position, staying in nest box and feeding using continuous focal animal sampling method. Simultaneously, the calls emitted in the experimental room were recorded by a single microphone centrally located and categorized as affiliative (whirr, chirp), contact (phee), long distance (loud shrill), agonistic (twitter) and alarm (tsik, seep, see). EA was assessed on the third hour after lights onset on the last week of each condition. In a first session, marmosets were exposed to one unfamiliar object during 15 min and 24h later, on the second session, a novel object was added to evaluate RM. Results showed that long days caused a decreased of amplitude and period variance of the CRA, but not short days. Short days decreased the total daily activity and active phase duration. On long days, active phase duration increased due to an advance of activity onset in relation to symmetric days. However, not all subjects started the activity earlier on long days. The activity offset was similar to symmetric days for the majority of marmosets. Results of EA showed that RM was not affected by short or long days, and that the marmosets exhibited a decreased in duration of EA on long days. Frequency and type of calls and frequency of anxiety-like behaviors, staying in nest box and grooming were lower on the first two light hours on long days. Considering the whole active phase of marmosets as we elucidate the results of vocalizations and behaviors, it is possible that these changes in the first two light hours are due to the shifting of temporal distribution of marmoset activities, since some animals did not advance the activity onset on long days. Consequently, the marmosets mean decreased because the sampling was not possible. In conclusion, marmosets synchronized the CRA to the tested photoperiods and as the phase angle varied a lot among marmosets it is suggested that they can use different strategies. Also, long days had an effect on activity-rest cycle and exploratory behaviors

Qualidade do solo da camada de cobertura final em área de disposição de resíduos no semiárido tropical

The final disposal of municipal solid waste in unsuitable areas without an infrastructure that meets the health measures and environmental protection, coupled with the lack of technical criteria in phase and decommissioning of the dump can promote environmental degradation. Alternatively to minimize the impacts of this activity for the stabilization of the area by isolating the massive waste with implementation of an adequate and finished by a layer of soil for plant growth final cover system. In this context, the present study aimed to evaluate the quality of the final cover in the area of a disabled dump the tropical semi-arid region in order to assist the process of recovery of these areas. The study area is located in the tropical semi-arid region in São João do Sabugi /RN. Soil samples were collected in the dump area and bushland as a benchmark of quality. To which they were subjected to analysis of physical attributes (particle density, bulk density, grain size and porosity), chemical properties (pH, K + , Na+ , Ca2 + , Mg2 + and Al3 + exchangeable, potential acidity, available phosphorus, sum of bases, CEC, base saturation, aluminum saturation, saturation Na + and adsorption ratio sodium, total organic carbon and total nitrogen) and total and soluble concentrations of heavy metals (Mn, Pb, Zn, Cd, Cu, Mo, Co, Cr, Ba and Ni). The differences between physical and chemical soil under native forest and final cover showing reduction of soil quality in the area off to the dump, which hinders the development of native vegetation and the recovery of the area. The absence of superior waterproofing to allow vertical transfer between the solid waste and the final cover promoted enrichment by chemical elements and heavy metals in excess can impair revegetation. Deficiencies found in the construction process of the final cover point to the need for intervention to accelerate the process of stabilization and recovery of the area of the local ecosystem

Influência do uso de combustíveis alternativos na síntese por combustão via microondas para a produção de materiais cerâmicos com estrutura espinélio

The development and study of detectors sensitive to flammable combustible and toxic gases at low cost is a crucial technology challenge to enable marketable versions to the market in general. Solid state sensors are attractive for commercial purposes by the strength and lifetime, because it isn t consumed in the reaction with the gas. In parallel, the use of synthesis techniques more viable for the applicability on an industrial scale are more attractive to produce commercial products. In this context ceramics with spinel structure were obtained by microwave-assisted combustion for application to flammable fuel gas detectors. Additionally, alternatives organic-reducers were employed to study the influence of those in the synthesis process and the differences in performance and properties of the powders obtained. The organic- reducers were characterized by Thermogravimetry (TG) and Derivative Thermogravimetry (DTG). After synthesis, the samples were heat treated and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), analysis by specific area by BET Method and Scanning Electron Microscopy (SEM). Quantification of phases and structural parameters were carried through Rietveld method. The methodology was effective to obtain Ni-Mn mixed oxides. The fuels influenced in obtaining spinel phase and morphology of the samples, however samples calcined at 950 °C there is just the spinel phase in the material regardless of the organic-reducer. Therefore, differences in performance are expected in technological applications when sample equal in phase but with different morphologies are tested