O papel das rotas e da obtenção de informações sobre a eficiência no forrageio de dinoponera quadriceps em ambiente natural

In this study, we investigated the role of routes and information attainment for the queenless ant species Dinoponera quadriceps foraging efficiency. Two queenless ant colonies were observed in an area of Atlantic secondary Forest at the FLONA-ICMBio of Nisia Floresta, in the state of Rio Grande do Norte, northeastern Brazil, at least once a week. In the first stage of the study, we observed the workers, from leaving until returning to the colony. In the second stage, we introduced a acrylic plate (100 x 30 x 0,8 cm) on a selected entrance of the nest early in the morning before the ants left the nest. All behavioral recordings were done through focal time and all occurence samplings. The recording windows were of 15 minutes with 1 minute interval, and 5 minute intervals between each observation window. Foraging was the main activity when the workers were outside the nest. There was a positive correlation between time outside the nest and distance travelled by the ants. These variables influenced the proportion of resource that was taken to the nest, that is, the bigger its proportion, the longer the time outside and distance travelled during the search. That proportion also influenced the time the worker remained in the nest before a new trip, the bigger the proportion of the item, the shorter was the time in the nest. During all the study, workers showed fidelity to the route and to the sectors in the home range, even when the screen was in the ant´s way, once they deviated and kept the route. The features of foraging concerning time, distance, route and flexibility to go astray by the workers indicate that decisions are made by each individual and are optimal in terms of a cost-benefit relation. The strategy chosen by queenless ants fits the central place foraging and marginal value theorem theories and demonstrate its flexibility to new informations. This indicates that the workers can learn new environmental landmarks to guide their routes

Uso de rotas na área de uso e a relação com comportamento alimentar em Callithrix jacchus

Callithrix jacchus are small primates that live in cooperative reproductive family groups. They explore their home range in search of fruits, exudates and animal prey. In this study we investigate the existence of traveling routes and its relation with the feeding habits in a group of Callithrix jacchus. The group was followed for 6 months in an area of Atlantic secondary Forest at the FLONA-ICMBio of Nísia Floresta, Rio Grande do Norte. Two observers in alternated days collected data referring to the group s location using a GPS navigation device, plotting data in 5 minute intervals, and with a position accuracy under 9 meters. All behavioral recordings were done through focal time samplings. The recording windows were 15 minutes with 1 minute intervals. The main activity was foraging, which propelled the animals to explore the environment with inconsistent intensity through the months, and correlated with the location of fruits, exudates and sleeping sites. From another standpoint, most activities were focused in the core areas that featured most sleeping sites, exudates trees and fruit trees. Insects, mostly Orthopterans, were hunted in all areas. The greater ratio of movement was registered during the last hours of sunlight, when animals returned to the sleeping sites and ate a greater number of fruits. The spatial and seasonal distribution of fruits forced the animals to travel long routes. The capacity to remember the location and navigate efficiently through feeding sources is important to save energy and time costs. Learning and familiarizing with the environment through the use of landmarks and acquisition of new information is extremely important to increase the chances of survival in a constantly changing environment

Avaliação da política pública de acessibilidade no período de 1992 a 2002 na Cidade do Natal

Este estudio tiene como objetivo evaluar los avances y límites de las políticas de accesibilidad en la ciudad de Natal. Se investigan las políticas publicas municipales de accesibilidad implantadas en los diez años subsecuentes, a partir de la sanción de la Ley Municipal de Accesibilidad Nº 4.090 del 03 de junio de 1992, que torna obligatorio la eliminación de las barreras arquitectónicas para personas con discapacidades en los lugares de circulación de peatones y edificios de uso público de la ciudad. Accesibilidad, en los proyectos de arquitectura y urbanismo es la condición esencial para asegurar a cualquier ciudadano su derecho a ir y venir con seguridad, dignidad y autonomía. Esta investigación se concentra en los barrios de: ciudad alta, Petrópolis y Ribeira, ya que esta área, en el período ya mencionado, fue la que tuvo una mayor concentración del presupuesto de inversiones públicas municipales de la ciudad de Natal, en la eliminación de barreras arquitectónicas en vías urbanas. El método adoptado fue el hipotético deductivo, a partir de la formulación de dos hipótesis de trabajo: la primera, una divergencia entre los objetivos propuestos por la Ley Nº 4.090 y sus aplicaciones prácticas y, la segunda, de las diferencias que existen en el grado de entendimiento del concepto de accesibilidad, para eso, se realizó una colecta y análisis de datos tanto empíricos como teóricos. Este estudio también retrata en el año de 2004, con el uso de la técnica de la fotografía, la realidad actual de la ciudad sirviendo como un parámetro comparativo con los proyectos asociados a la Coordinación para integración de las personas con discapacidades. Se utiliza la técnica de entrevista con especialistas en accesibilidad envueltos a lo largo del proceso de implantación de las políticas públicas en la ciudad de Natal, durante los años mencionados, obteniendo así un testimonio sobre las directrices adoptadas en ese período, con base en la legislación vigente. En la investigación documental y fotográfica se realiza una evaluación de la dimensión real de lo propuesto y ejecutado en un periodo de diez años, y se concluye sobre todos los avances y retrocesos de las políticas de gestiones públicas adoptadas con relación a la accesibilidad en la ciudad de Natal

Uma cidade para pessoas: funcionalidade, racionalidade e emotividade nas relações mobiliário urbano, espaço público e cidadãos

This research investigates how functionality, rationality, and emotionality applied to urban furniture design contribute to the organization, legibility, and qualification of public spaces, according to different layouts, physical and visual qualities of the urban furniture as well as the quality of urban infrastructure that may influence the uses and appropriation of urban spaces by pedestrians, turning those spaces into socially centripetal or centrifugal places. The work consists of two parts. First refers to a bibliographical review concerning two main issues of the investigation: product design and legibility of public space, defining the conceptual and theoretical bases, linked to methodological strategies aimed at systemic planning and integrated management of urban furniture design and legibility of public spaces (sidewalks), that are necessary to define the existing relationships among the user s interface (pedestrians); product (urban artifacts); built environment (sidewalks). The second part refers to the achievement of empirical approach throughout visual analysis of public spaces and the functional and qualitative evaluation of the existing urban furniture in the central neighborhood of Cidade Alta, Natal, RN, according to the theoretical researched concepts and methodological procedures. The results expose the weaknesses and levels of intensity arising from the relations among public space, urban furniture, and users, revealing the need for theoretical and practical approaches which would help the decision-making in planning, designing and integrating innovative, sustainable, and ethical solutions in order to design attractive public spaces that could provide sociability and citizenship throughout integrated public management, city systemic thinking and urban identity. The suggested guidelines at the end of this research will provide the necessary strategies to design suitable urban furniture systems according to aesthetic and practical urban infrastructure and city context, aiming to ease visual and physical conflicts that may negatively interfere with the appropriation of public spaces by the citizens

Arquitetura da (in)segurança: estudando relações entre configuração espacial, artifícios de segurança e violência urbana no bairro Manaíra, João Pessoa, Paraíba

João Pessoa, the capital city of the state of Paraíba (Northeast Brazil), is reputed throughout the country as a quiet place, although it has been acquiring, over the past years, an urban character with social implications similar to those of major metropolitan Brazilian areas. The new situation is evident by the social inequalities, with the creation of confined spaces, which segregate and cause enclosure of the inhabitants, leading to death the public space. This study correlates accessibility in spatial structure with two types of crime data, burglary and robbery, recorded in 2008 and 2009, by the Secretaria de Segurança da Paraíba (The government agency public in charge of safety), in the district of Manaíra, an upper middle class neighborhood, which has, in recent times, been considered one of the most violent areas in João Pessoa. Sought to understand connections between these events and morpho-social aspects of the built environment, where examined the spatial properties, such as accessibility of the urban net, the presence of control measures, the safety of buildings and their uses. Spatial properties were also validated by the observation of pedestrian flows at strategic points of the study area. It was concluded that the presence of intense flows helps to attract potential thieves, physical security and control offers little protection

Sinterização de aço inoxidável reforçado com partículas nanométricas dispersas de carbeto de nióbio - NbC

Metal powder sintering appears to be promising option to achieve new physical and mechanical properties combining raw material with new processing improvements. It interest over many years and continue to gain wide industrial application. Stainless steel is a widely accepted material because high corrosion resistance. However stainless steels have poor sinterability and poor wear resistance due to their low hardness. Metal matrix composite (MMC) combining soft metallic matrix reinforced with carbides or oxides has attracted considerable attention for researchers to improve density and hardness in the bulk material. This thesis focuses on processing 316L stainless steel by addition of 3% wt niobium carbide to control grain growth and improve densification and hardness. The starting powder were water atomized stainless steel manufactured for Höganäs (D 50 = 95.0 μm) and NbC produced in the UFRN and supplied by Aesar Alpha Johnson Matthey Company with medium crystallite size 16.39 nm and 80.35 nm respectively. Samples with addition up to 3% of each NbC were mixed and mechanically milled by 3 routes. The route1 (R1) milled in planetary by 2 hours. The routes 2 (R2) and 3 (R3) milled in a conventional mill by 24 and 48 hours. Each milled samples and pure sample were cold compacted uniaxially in a cylindrical steel die (Ø 5 .0 mm) at 700 MPa, carried out in a vacuum furnace, heated at 1290°C, heating rate 20°C stand by 30 and 60 minutes. The samples containing NbC present higher densities and hardness than those without reinforcement. The results show that nanosized NbC particles precipitate on grain boundary. Thus, promote densification eliminating pores, control grain growth and increase the hardness values

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

Desevolvimento de nanocompósitos de poli(metacrilato de metila)/argila processados por mistura no estado fundido

Poly(methyl methacrylate)/clay nanocomposites were prepared by melt mixing using a montmorillonite-rich clay (MMT). The clay in natura was treated with acrylic acid to facilitate the dispersion in the polymer matrix. A masterbatch of PMMA/clay was prepared and combined with the pure PMMA and then subjected to extrusion process using singlescrew and twin-screw extruders followed by injection. Nanocomposites were processed with clay contents of 1, 3, 5 and 8 wt.%. The effect of shear processing on the morphology of the nanocomposites was evaluated by XRD, SEM and TEM. Thermal and mechanical properties of the nanocomposites were investigated through TGA, DSC, HDT, VICAT, tensile and impact tests, to evaluate the effect of the addition of clay to the PMMA matrix. Flammability tests were also conducted to investigate the effect of the addition of clay on the flame retardation properties. SEM images of the nanocomposites indicated the presence of clay agglomerates, which resulted in the reduction of properties such as thermal stability, mechanical strength and impact resistance, and increased the rate of burning for materials processed by both extrusion routes

Síntese e impregnação de peneiras moleculares Fe MCM-41 derivada de sílica da casca do arroz

The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100°C for 168 hours, later the precursor was calcinated at 550°C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization, identifying the presence of hexagonal structure typical for mesoporous materials, as well as observation of the MCM41 and iron of characteristic bands.

Preparação de óxidos mistos de níquel e zinco nanoparticulados a partir de combustíveis alternativos

The field of "Materials Chemistry" has been developing in recent years and there has been a great increase of interest in the synthesis and chemical and physical properties of new inorganic solids. New routes of synthesis and synthesis modified has been developed with the aim not only to optimize the processes in laboratory scale, but also on an industrial scale, and make them acceptable by current environmental legislation. The phenomenology of current solid state chemistry properties coupled with the high temperature superconductivity, ferromagnetism, porosity molecular and colors are evidence affected by the synthesis method, which in turn can influence the technological application of these materials. From this understanding, mixed oxides of nickel and zinc nanoparticulate were synthesized by microwave-assisted combustion route using three specific types of organic fuels employing the weight ratios 1:1/2 and 1:1 of cation metallic/fuel, in order to investigate the influence of such proportions to obtain the solids. The new fuels were chosen to replace, for example, urea or glycine that are the fuels most commonly preferred in this kind of synthesis. The powders without heat treatment were studied by Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD) and then calcined at 900°C. After heat treatment, the samples were characterized by analysis of X Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The modified synthesis route porposed was effective for obtaining powders. Both the alternative fuels chosen as the different weight ratios employed, influenced in the morphology and obtaining oxides

Síntese de zeólita A a partir de diatomita como fonte de aluminossilicato

The synthesis of zeolites from natural sources of silicon and aluminum are promising alternative routes to obtain porous or zeolite MCM family. Such materials are typically used in catalytic processes and / or adsorption is to obtain new products or for separation and purification processes thereof. Environmental legislation is becoming stricter and requires the use of materials more efficient, aiming to achieve pollution prevention, by gas or liquid contaminants in the environment. In order to obtain a material with environmentally friendly features, this study aimed at the synthesis of zeolite A, from an amorphous sediment, diatomite, which is found in abundance in the northeast region of Brazil, may be substituted for conventional products the production of zeolite, involving higher costs. The methodology for obtaining the "Zeolite A" using as a source of silica and alumina diatomite is simple, since this is a source of silicon, not requiring therefore a structural driver, but also by heat treatment, only drying conventional to remove water. The "zeolite A" was obtained from diatomite, but as an intermediate step we obtained the sodalite. The characterization was made by the following techniques: EDX, XRD, FT-IR, SEM and determining a specific area by the BET method and the BJH method for checking the diameter of pores. By characterization of the obtained material was first demonstrated the achievement of sodalite and after modification of the same, there was obtained zeolite A

Influência do método de síntese e caracterização de pós compósitos de NiO- Ce1-xEuxO2-δ para anodos catalíticos de células a combustível

Fuel cells are electrochemical devices that convert chemical energy into electricity. Due to the development of new materials, fuel cells are emerging as generating clean energy generator. Among the types of fuel cells, categorized according to the electrode type, the solid oxide fuel cells (SOFC) stand out due to be the only device entirely made of solid particles. Beyond that, their operation temperature is relatively high (between 500 and 1000 °C), allowing them to operate with high efficiency. Another aspect that promotes the use of SOFC over other cells is their ability to operate with different fuels. The CeO2 based materials doped with rare earth (TR+3) may be used as alternatives to traditional NiO-YSZ anodes as they have higher ionic conductivity and smaller ohmic losses compared to YSZ, and can operate at lower temperatures (500-800°C). In the composition of the anode, the concentration of NiO, acting as a catalyst in YSZ provides high electrical conductivity and high electrochemical activity of reactions, providing internal reform in the cell. In this work compounds of NiO - Ce1-xEuxO2-δ (x = 0.1, 0.2 and 0.3) were synthesized from polymeric precursor, Pechini, method of combustion and also by microwave-assisted hydrothermal method. The materials were characterized by the techniques of TG, TPR, XRD and FEG-SEM. The refinement of data obtained by X-ray diffraction showed that all powders of NiO - Cex-1EuxO2-δ crystallized in a cubic phase with fluorite structure, and also the presence of Ni. Through the characterizations can be proved that all routes of preparation used were effective for producing ceramics with characteristics suitable for application as SOFC anodes, but the microwave-assisted hydrothermal method showed a significant reduction in the average grain size and improved control of the compositions of the phases

Estudo da sinterização de eletrólito sólido de céria dopada com gadolínia

Fuel cells are electrochemical devices that convert chemical energy in electrical energy by a reaction directly. The solid oxide fuel cell (SOFC) works in temperature between 900ºC up to 1000ºC, Nowadays the most material for ceramic electrolytes is yttria stabilized zirconium. However, the high operation temperature can produce problems as instability and incompatibility of materials, thermal degradation and high cost of the surround materials. These problems can be reduced with the development of intermediate temperature solid oxide fuel cell (IT-SOFC) that works at temperature range of 600ºC to 800ºC. Ceria doped gadolinium is one of the most promising materials for electrolytes IT-SOFC due high ionic conductivity and good compatibility with electrodes. The inhibition of grain growth has been investigated during the sintering to improve properties of electrolytes. Two-step sintering (TSS) is an interesting technical to inhibit this grain growth and consist at submit the sample at two stages of temperature. The first one stage aims to achieve the critical density in the initiating the sintering process, then the sample is submitted at the second stage where the temperature sufficient to continue the sintering without accelerate grain growth until to reach total densification. The goal of this work is to produce electrolytes of ceria doped gadolinium by two-step sintering. In this context were produced samples from micrometric and nanometric powders by two routes of two-step sintering. The samples were obtained with elevate relative density, higher than 90% using low energy that some works at the same area. The average grain size are at the range 0,37 μm up to 0,51 μm. The overall ionic conductivity is 1,8x10-2 S.cm and the activation energy is 0,76 eV. Results shown that is possible to obtain ceria-doped gadolinium samples by two-step sintering technique using modified routes with characteristics and properties necessary to apply as electrolytes of solid oxide fuel cell

Síntese de nanopartículas de magnetita via decomposição térmica em meio não-aquoso

This work aims at obtaining nanoparticles of iron oxide, the magnetite one (Fe3O4), via synthesis by thermal decomposition through polyol. Thus, two routes were evaluated: a simple decomposition route assisted by reflux and a hydrothermal route both without synthetic air atmosphere using a synthesis temperature of 260ºC. In this work observed the influence of the observe of surfactants which are generally applied in the synthesis of iron oxide nanoparticles decreasing cluster areas. Further, was observed pure magnetite phase without secondary phases generally found in the iron oxide synthesis, a better control of crystallite size, morphology, crystal structure and magnetic behavior. Finally, the introduction of hydroxyl groups on the nanoparticles surface was analyzed besides its employment in the polymer production with OH radicals. The obtained materials were characterized by XRD, DLS, VSM, TEM, TG and DSC analyses. The results for the magnetite obtainment with a particle size greater than 5 nm and smaller than 11 nm, well defined morphology and good magnetic properties with superparamagnetic behavior. The reflux synthesis was more efficient in the deposition of the hydroxyl groups on the nanoparticles surface

Síntese hidrotérmica assistida por micro-ondas de tiO2, e aplicação em nanocompósito

In recent decades have seen a sharp growth in the study area of nanoscience and nanotechnology and is included in this area, the study of nanocomposites with self-cleaning properties. Since titanium dioxide (TiO2) has high photocatalytic activity and also antimicrobial, self-cleaning surfaces in your application has been explored. In this study a comparison was made between two synthesis routes to obtain TiO2 nanoparticles by hydrothermal method assisted by microwave. And after analysis of XRD and SEM was considered the best material for use in nanocomposites. It was deposited nanocomposite film of poly (dimethyl siloxane) (PDMS) with 0.5, 1, 1.5 and 2% by weight of nanoparticles of titanium dioxide (TiO2) by the spraying method. The nanocomposite was diluted with hexane and the suspension was deposited onto glass substrate, followed by curing in an oven with forced air circulation. The photocatalytic activity of the nanocomposite impregnated with methylene blue was evaluated by UV- vis spectroscopy from the intensity variation of absorption main peak at 660nm with time of exposure to the UV chamber. Changes in the contact angle and microhardness were analyzed before and after UV aging test. The effect of ultraviolet radiation on the chemical structure of the PDMS matrix was evaluated by spectrophotometry Fourier transform infrared (FTIR).The results indicated that the addition of TiO2 nanoparticles in the coating PDMS gave high photocatalytic activity in the decomposition of methylene blue, an important characteristic for the development of self-cleaning coatings