Growth And Characterization Of Diammonium Hydrogen Citrate And Citric Acid Monohydrate Single Crystals

Over the past years there has been considerable interest in the growth of single crystals both from the point of view of basic research and technological application. With the revolutionary emergence of solid state electronics which is based on single crystal technolo8Ys basic and applied studies on crystal growth and characterization _have gained a-more significant role in material science. These studies are being carried out for single crystals not only of semiconductor and other electronic materials but also of metals and insulators. Many organic crystals belonging to the orthorhombic class exhibit ferroelectric, electrooptic, triboluminescent and piezoelectric properties. Diammonium Hydrogen Citrate (DAHC) crystals are reported to be piezoelectric and triboluminescent /1/. Koptsik et al. /2/ have reported the piezoelectric nature of Citric Acid Monohydrate (CA) crystals. And since not much work has been done on these crystals, it has been thought useful to grow and characterize these crystals. This thesis presents a study of the growth of these crystals from solution and their defect structures. The results of the microindentation and thermal analysis are presented. Dielectric, fractographic, infrared (IR) and ultraviolet (UV) studies of DAHC crystals are also reported

Flood Risk Assessment in Coastal Drainage Basins through a Multivariate Analysis within a GIS-Based Model

This paper presents a GIS-based multicriteria flood risk assessment and mapping approach applied to coastal drainage basins where hydrological data are not available. It involves risk to different types of possible processes: coastal inundation (storm surge), river, estuarine and flash flood, either at urban or natural areas, and fords. Based on the causes of these processes, several environmental indicators were taken to build-up the risk assessment. Geoindicators include geological-geomorphologic proprieties of Quaternary sedimentary units, water table, drainage basin morphometry, coastal dynamics, beach morphodynamics and microclimatic characteristics. Bioindicators involve coastal plain and low slope native vegetation categories and two alteration states. Anthropogenic indicators encompass land use categories properties such as: type, occupation density, urban structure type and occupation consolidation degree. The selected indicators were stored within an expert Geoenvironmental Information System developed for the State of Sao Paulo Coastal Zone (SIIGAL), which attributes were mathematically classified through deterministic approaches, in order to estimate natural susceptibilities (Sn), human-induced susceptibilities (Sa), return period of rain events (Ri), potential damages (Dp) and the risk classification (R), according to the equation R=(Sn.Sa.Ri).Dp. Thematic maps were automatically processed within the SIIGAL, in which automata cells (""geoenvironmental management units"") aggregating geological-geomorphologic and land use/native vegetation categories were the units of classification. The method has been applied to the Northern Littoral of the State of Sao Paulo (Brazil) in 32 small drainage basins, demonstrating to be very useful for coastal zone public politics, civil defense programs and flood management.

Proposta de sistemática para a avaliação e controle de custos em propriedades rurais : o caso de uma empresa de criação de gado

Esta dissertação discute a gestão de Custos em propriedades rurais, tendo como objetivo principal a proposição de uma sistemática para avaliação e controle de custos em propriedades rurais, bem como mensurar os custos unitários dos produtos resultantes dos processos de produção referentes à pecuária. Para formulação desta sistemática, revisou-se a literatura sobre as mudanças ocorridas no decorrer dos últimos anos no setor primário da economia brasileira bem como, os sistemas de gestão em propriedades rurais. Uma revisão literária sobre os princípios de custeio (total, parcial e variável) e métodos de custeio (custo padrão, centro de custos e custeio baseado em atividades) também foi efetuada. A sistemática proposta foi estruturada em seis etapas: (1) análise dos contextos interno e externo da propriedade rural; (2) identificação da base conceitual; (3) estruturação do sistema de custos; (4) escolha do sistema de custos a utilizar; (5) aplicação prática do sistema de custos e análise da Evolução dos custos; (6) avaliação do resultado e identificação das oportunidades de melhoria. Com a aplicação prática do modelo em uma propriedade rural da região oeste do estado do Rio Grande do Sul foi possível concluir que a sistemática alcançou os objetivos já citados, e que a aplicação do método ABC seria um complemento refinado ao sistema de custos da empresa.

Além das versões: possibilidades da narrativa em entrevistas de história oral

The work with oral history consists of recording interviews which have historical and documental proprieties, with actors/actresses or witnesses of events, conjunctures, movements, institutions and ways of living along the contemporary history. One of its basic foundations is the narrative. An event or a situation lived by the interviewee can not be transmitted to any other person without being narrated. That means that it frames itself (meaning that it does become something) at the very moment of the interview. By telling his/her life experiences, the interviewee transforms what has been lived into language, selecting and organizing facts according to some determined meanings. This work of language in crystallising images (images which refer to, and mean again, life experience) is common in all narratives - and we do know that sometimes it is much more successful than others (just the way some oral history interviews are certainly more successful than others). However, perhaps we have not given yet all the attention needed to this work of language in the oral sources.

Balance-bot

Research on inverted pendulum has gained momentum over the last decade on a number of robotic laboratories over the world; due to its unstable proprieties is a good example for control engineers to verify a control theory. To verify that the pendulum can balance we can make some simulations using a closed-loop controller method such as the linear quadratic regulator or the proportional–integral–derivative method. Also the idea of robotic teleoperation is gaining ground. Controlling a robot at a distance and doing that precisely. However, designing the tool to takes the best benefit of the human skills while keeping the error minimal is interesting, and due to the fact that the inverted pendulum is an unstable system it makes a compelling test case for exploring dynamic teleoperation. Therefore this thesis focuses on the construction of a two-wheel inverted pendulum robot, which sensor we can use to do that, how they must be integrated in the system and how we can use a human to control an inverted pendulum. The inverted pendulum robot developed employs technology like sensors, actuators and controllers. This Master thesis starts by presenting an introduction to inverted pendulums and some information about related areas such as control theory. It continues by describing related work in this area. Then we describe the mathematical model of a two-wheel inverted pendulum and a simulation made in Matlab. We also focus in the construction of this type of robot and its working theory. Because this is a mobile robot we address the theme of the teleoperation and finally this thesis finishes with a general conclusion and ideas of future work.

New bacterial cellulose nanocomposites prepared by in situ radical polymerization of methacrylate monomers

Bacterial cellulose/polymethacrylate nanocomposites have received attention in numerous areas of study and in a variety of applications. The attractive properties of methacrylate polymers and bacterial cellulose, BC, allow the synthesis of new nanocomposites with distinct characteristics. In this study, BC/poly(glycidylmethacrylate) (BC/PGMA) and BC/poly(ethyleneglycol)methacrylate (BC/PPEGMA) nanocomposites were prepared through in situ free radical polymerization of GMA and PEGMA, respectively. Ammonium persulphate (APS) was used as an initiator and N,N’methylenebisacrilamide (MBA) was used as a crosslinker in BC/PGMA. Chemical composition, morphology, thermal stability, water absorption, mechanic and surface properties were determined through specific characterization techniques. The optimal polymerization was obtained at (1:2) for BC/PGMA, (1:2:0.2) ratio for BC/GMA/MBA and (1:20) for BC/PPEGMA, with 0.5% of initiator at 60 ºC during 6 h. A maximum of 67% and 87% of incorporation percentage was obtained, respectively, for the nanocomposites BC/PGMA/MBA and BC/PPEGMA. BC/PGMA nanocomposites exhibited an increase of roughness and compactation of the three-dimensional structure, an improvement in the thermal and mechanical properties, and a decrease in their swelling ability and crystallinity. On the other hand, BC/PPEGMA showed a decrease of stiffness of three-dimensional structure, improvement in thermal and mechanical properties, an increase in their swelling ability and a decrease the crystallinity. Both BC/polymethacrylate nanocomposites exhibited a basic surface character. The acid treatment showed to be a suitable strategy to modifiy BC/PGMA nanocomposites through epoxide ring-opening reaction mechanism. Nanocomposites became more compact, smooth and with more water retention ability. A decrease in the thermal and mechanical proprieties was observed. The new nanocomposites acquired properties useful to biomedical applications or/and removal of heavy metals due to the presence of functional groups.

Gestão da cadeia de suprimento e vantagem competitiva: uma análise em setores industriais a partir da visão relacional

This work has as its main purpose to investigate the contribution of supply chain management in order to obtain competitive advantage by companies from the textile industry and from Ceará footwear industry, focusing its analysis mainly in the interorganizational relations (dyadic). For this, the theoretical referential contemplates different explanatory streams of the competitive advantage, detaching the relational perception of the resources theory, as well as, the main presuppositions of the supply chain management which culminates with the development of an analysis sample that runs the empirical study; the one which considers an expanded purpose of the supply chain which includes the government and the abetment institutions as institutional environment representatives. Besides supply chain management consideration as a competitive advantage source, the work also tried to identify other possible competitive advantage sources for the companies of the investigated sectors. It represents a study of multiple interpretive cases, having four cases as a total; meaning two cases in each one of the sectors, which used as a primary data collecting instrument a semi-structured interview schedule. Different methods were used for the data analysis, the content analysis and the constant comparison methods, the analytical procedure originated from the grounded theory research strategy, which were applied the Atlas/ti software recourse. Considering the theoretical referential and the used analysis sample, four basic categories of the work were defined, including its respective proprieties and dimensions: (1) characteristics concerning to the relationship with the supplier; (2) the company relations with the government; (3) the company relations with the abetment institutions and; (4) obtaining sources of competitive advantage. In general, the applied research in the footwear sector revealed that in the relationships of the researched companies related to its suppliers, there is a predominance of the partnership system and the main presuppositions of the supply chain management are applied which contributes for the acquisition of the relational competitive advantage; while in the textile sector, only some of these presuppositions are applied, with little contribution for the relational competitive advantage. The main resource which was accessed by the companies in both sectors through its relationships with the government and the abetment institutions are the tax incentives which, for the footwear companies, contribute for the acquisition of the temporary competitive advantage in relation to the contestants who do not own productive installations in the Northeast region, it also conducts to a competitive parity situation in relation to the contestants who own productive installations in the Northeast region and to the external market contestants; while for the companies of the textile sector, the tax incentives run the companies to a competitive parity situation in relation to its contestants. Furthermore, the investigated companies from the two sectors possess acquisition sources of the competitive advantage which collimate with different explanatory streams (industrial analysis, resources theory, Austrian school and the dynamic capabilities theory), although there is a predominance of the product innovation as a competitive advantage source in both sectors, due to the bond of these with the fashion tendencies

Entre o mar e estrela, um lugar para se bem viver : a problemática da expansão urbana da Cidade de Baía Formosa/RN

The urban expansion problem of Baía Formosa, a southern edge city of de Rio Grande do Norte eastern coast, which has been presented in other coast Brazilian towns, specially on those with tourist activities increase. Therefore, this situation brings huge concerns to their inhabitants, to their technical /scientific community and to the governments, because of the conflicts of interest and of the growth of urban problems that this has been created. At Baía Formosa, the situation is aggravated because the city is confined, once around it, there are large private proprieties, environmental preservation area and the sea, at the eastern edge. The objectives of this study are the analyses of this city expansion process in order to obtain adequate alternatives and defining methodology to apply in other urban nucleus that are subjected to similar situations. Of course, presents social relations, environmental conditions and promoting local population insertion should be considered in order that enjoin this process and contributing to a better social balance. This case study has used bibliography research, field data, maps and soil occupation recorders and photographs of the area, besides the primary data gathering by surveys carried out with many social actors. The present analysis shows that the urban expansion observed today is featured by a recent unsustainable model, which attacks the environment and brings either farm conflicts. On the other hand, the ecological tourism can represent an alternative in order to achieve an adequate expansion form, without forgetting the several structural parameters necessary to support the sustainable activities

Avaliação do estresse oxidativo induzido por superfícies de titânio

Commercially pure Titanium (cp Ti) is a material largely used in orthopedic and dental implants due to its biocompatibility properties. Changes in the surface of cp Ti can determine the functional response of the cells such as facilitating implant fixation and stabilization, and increased roughness of the surface has been shown to improve adhesion and cellular proliferation. Various surface modification methods have been developed to increase roughness, such as mechanical, chemical, electrochemical and plasma treatment. An argon plasma treatment generates a surface that has good mechanical proprieties without chemical composition modification. Besides the topography, biological responses to the implant contribute significantly to its success. Oxidative stress induced by the biomaterials is considered one of the major causes of implant failure. For this reason the oxidative potential of titanium surfaces subjected to plasma treatment was evaluated on this work. CHO-k1 cells were cultivated on smooth or roughed Ti disks, and after three days, the redox balance was investigated measuring reactive oxygen species (ROS) generation, total antioxidant capacity and biomarkers of ROS attack. The results showed cells grown on titanium surfaces are subjected to intracellular oxidative stress due to hydrogen peroxide generation. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular ability. Our data suggest that plasma treated titanium may be a more biocompatible biomaterial.

Estudo de sistemas vítreos para infiltração em alumina

The system in-Ceram Alumina, produced by VITA, consists in a technique of prepare of a substructure of ceramics to dental crowns. First burning is made in the alumina decanted by slip casting process under a stone die that reproduces the tooth prepared to receive a crown. In a second burning, alumina is infiltrated by vitreous system, giving to this set a high mechanic resistance. In this work, it s made a study of the composition of a new infiltrating material more used nowadays, giving to alumina desirable mechanics proprieties to its using like substructure of support to ceramic s crown used in the market today. The addition of Lanthanum oxide (frit A) and calcium oxide (frit B) was made in attempt to increase the viscosity of LZSA and to reduce fusion temperature. The frits were put over samples of alumina and took to the tubular oven to 1400ºC under vacuum for two groups (groups 1 and 2). For another two groups (groups 3 and 4) it was made a second infiltration, following the same parameters of the first. A fifth group was utilized like group of control where the samples of pure alumina were not submitted to any infiltrating process. Glasses manifested efficient both in quality and results of analysis of mechanic resistance, being perfectly compatible with oral environment in this technical requisite. The groups that made a second infiltration had he best results of fracture toughness, qualify the use in the oral cavity in this technical question. The average of results achieved for mechanic resistance to groups 1, 2, 3, 4 and 5 were respectively 98 MPa, 90 MPa, 144 MPa, 236 MPa and 23 MPa

Estudo do comportamento plástico, mecânico, microestrutural e térmico do concreto produzido com resíduo de porcelanato

Population growth experienced in major cities, allied to society s need of infra-structure, especially ones related to habitational demands, increases the consumption of construction materials. As a consequence, consumption of natural resources itself. Thus, due to this process, concrete is one of the most produced materials in civil construction. This is also due to the great diversity of its application, easiness in its execution and adequate mechanical performance, as well as low production costs. Following the same tendencies in construction development, the ceramic industry has intensified the production of porcelain ceramic tiles and floors. These are achieved by a fine finishing and receive polishing at the end of the fabrication process. This work researched the use of porcelain residues in polishing for the production of concrete. All of which; due to economical and environmental issues. This process aims to prove adequate destiny for this type of residue, due to environmental issues, incorporating it to the concrete itself; all of which provides economy in consumption of the materials that constitute concrete. Thus, the main characteristics of concrete were investigated through the inclusion of different concentration of the porcelain residue as additional trait element. The residue rates incorporated to the trait varied from 10% to 50% in relation to the cement mass, in the traits with plastic additives and without plastic additives. It is observed that the inclusion of porcelain residue produced a meaningful alteration in the consistency of fresh concrete. This residue has a fine granulometry and it considerably absorbed the water used in the concrete spreading, influencing the way this material is dealt with. Thus, the value of cement striking decreases with the increase of residues present in trait. The maximal incorporation of the residue was of 50%, massively, for the same factor water/initial cement. The use of residues in concrete results in an 40% increase in the compression resistance. It is also proportional to residue concentration of porcelain in the trait. The microstructure was also favored once porosity and concrete absorption decreases with the use of this residue. The parameters demonstrate the quality and durability of the concrete produced with this residue. The use of porcelain residue in concrete composition has not produced meaningful thermal behavior changes. Thermal conductivity, heat capacity and thermal diffusivity have been maintained basically constant

Nitretação em plasma com gaiola catódica: investigação do mecanismo e estudo comparativo com a nitretação em plasma de tensão contínua

The ionic plasma nitriding is one of the most important plasma assisted treatment technique for surface modification, but it presents some inherent problems mainly in nitriding pieces with complex geometries. In the last four years has appeared a plasma nitriding technique, named ASPN (Active Screen Plasma Nitriding) in which the samples and the workload are surrounded by a metal screen on which the cathodic potential is applied. This new technique makes possible to obtain a perfect uniform nitrided layer apart from the shape of the samples. The present work is based on the development of a new nitriding plasma technique named CCPN (Cathodic Cage Plasma Nitriding) Patent PI 0603213-3 derived from ASPN, but utilizes the hollow cathode effect to increase the nitriding process efficiency. That technique has shown great improvement on the treatment of several types of steels under different process conditions, producing thicker and harder layers when compared with both, ASPN and ionic plasma nitriding, besides eliminating problems associated with the later technique. The best obtained results are due to the hollow cathode effect on the cage holes. Moreover, characteristic problems of ionic plasma nitriding are eliminated due to the fact that the luminescent discharge acts on the cage wall instead of on the samples surface, which remains under a floating potential. In this work the enhancement of the cathodic cage nitriding layers proprieties, under several conditions for some types of steels was investigated, besides the mechanism for nitrides deposition on glass substrate, concluding that the CCPN is both a diffusion and a deposition process at the same time

Alteração da qualidade do solo em zona ripária sob diferentes usos: potencial de poluição para um manancial tropical

The demographic growth press environments that are more susceptible to perturbations, like riparian areas, without knowing about the effects of replacing these natural environments by different land uses on soil quality and, consequently, on watershed. The study of soil quality has evolved as an important tool for soil sustainable management of this component of the biosphere that affects aquatic and terrestrial ecosystems functions. Thus, physical and chemical soil proprieties were measured to assess soil quality under different land uses (agricultural, pasture, urban, industrial and natural vegetation,) in the riparian zone of Extremoz Lake, an important human water source, evaluating whether the soil offers potential risk to water pollution. Data were subjected to descriptive statistics and Principal Component Analysis (PCA). The results showed negative changes in soil quality such as alkalinization and increase in P, Pb, Mn and Zn contents in most anthropized areas. The sandy texture and low organic matter content in all soils showed the fragility of the soil to erosion and leaching of elements in excess to water bodies, evidencing that this soils has potential to diffuse contaminants. Conservative management of soil is necessary to provide an adequate ecological state in riparian zones of the Extremoz Lake, thus allowing controlling and buffering diffuse sources of pollution to this important water supply source

A construção da ponte metálica sobre o Rio Pontengi: aspectos históricos, construtivos e de durabilidade - Natal/RN, Brasil (1912-1916) - estudo de caso

It is a case study that reports the construction of metal truss bridge in the river Potengi in Natal, Rio Grande do Norte, between the years 1912 and 1916. From testimonials on steel bridges in Brazil and worldwide including foundations. Documentary research from procurement of projects and contracts was performed. A chronology of construction, with a description of the equipment used and its original budget with the Brazilian government. Still, we used interviews and surveys with experimental sampling / testimonies, laboratory tests. This study aims to analyze historically and technically the Bridge over the River Potengi, emphasizing primarily the construction process, the qualities and characteristics of the materials used and the technological, chemical, mineralogical and microstructural properties of cement and concrete used in its construction. Taking as conclusions that cements pozolônicos ensured a good durability to the concrete in a hundred-year period and that the solution employed with the compressed air caissons was right

Influência da adição de rejeitos cerâmicos nas propriedades de cerâmica vermelha da região do Recôncavo Baiano

The study of the physical and mechanic properties is an analysis of unquestioned importance on the production of the ceramic materials. In the region of the Recôncavo Baiano, there are ceramic and small brick factories, that still use rudimentary techniques, where the necessity of characterization of raw materials is denounced by the quality of the final product. The present work has for objective to study the behavior of the clay proceeding from the region of the Recôncavo, between the cities of Candeias and Camaçari/Ba, with addition of 5, 10 and 15% by weight of brick scraps, trying to optimize the physic and mechanical properties of the final product, aiming a better possibility of being manufactured, mechanic resistance, low linear retraction and water absorption. The brick scraps and the clay were characterized by FRX, DRX, TG, ATD and the granulometric analysis. Samples for testing where prepared by uniaxial pressing at 25Mpa, in 60x20x5mm size. The evaluated technological properties were: linear retraction, water absorption, apparent porosity and flexural strength. The samples were burned in electric oven in the temperatures of 850º, 950º and 1050ºC and compared its mechanical properties and the gresification. With addition of 15% by weight of brick scraps and burning at 900º-1000ºC the samples showed properties superior to that clay