Use of high energy ball milling on the sintering optimization of alumina ceramics

In this work, the effect of the milling time on the densification of the alumina ceramics with or without 5wt.%Y 2O 3, is evaluated, using high-energy ball milling. The milling was performed with different times of 0, 2, 5 or 10 hours. All powders, milled at different times, were characterized by X-Ray Diffraction presenting a reduction of the crystalline degree and crystallite size as function of the milling time increasing. The powders were compacted by cold uniaxial pressing and sintered at 1550°C-60min. Green density of the compacts presented an increasing as function of the milling time and sintered samples presented evolution on the densification as function of the reduction of the crystallite size of the milled powders. © (2010) Trans Tech Publications.

Efficiency evaluation of ZrB2 incorporation in the MgB 2 matrix phase using high-energy milling

The present study suggests the use of high energy ball milling to mix (to dope) the phase MgB2 with the AlB2 crystalline structure compound, ZrB2, with the same C32 hexagonal structure than MgB 2, in different concentrations, enabling the maintenance of the crystalline phase structures practically unaffected and the efficient mixture with the dopant. The high energy ball milling was performed with different ball-to-powder ratios. The analysis of the transformation and formation of phases was accomplished by X-ray diffractometry (XRD), using the Rietveld method, and scanning electron microscopy. As the high energy ball milling reduced the crystallinity of the milled compounds, also reducing the size of the particles, the XRD analysis were influenced, and they could be used as comparative and control method of the milling. Aiming the recovery of crystallinity, homogenization and final phase formation, heat treatments were performed, enabling that crystalline phases, changed during milling, could be obtained again in the final product. © (2010) Trans Tech Publications.

The urban female labour market in Latin America: the myth and the reality

Includes bibliography

In search of work. International migration of women in Latin America and the Caribbean. Selected bibliography

Includes bibliography

Bibliotecas, arquivos e museus como centros de referência na dimensão cultural das comunidades

With the evolution of the organizations theory, new management practices have transformed the institutions. The improvement of these management practices in cultural unities (UCs) is constant, and interacts in the international axis, since each unity increasingly communicate with other. As a reflection of organizational administrative practices, UCs had developed and assumed the organizational theories to make easy a framework for effective management practices. Comprehending the importance of the studies on UCs requires both a new approach of existing public politics for this field, and the recognition of the Information Science knowledge on area. In this way, it was planned to develop a model constituting a tool for managers in these institutions through the experience of laboratory works carried out with researchers from the European community. Libraries and museums are institutions that operate in the social process of their communities and the archives establish their structural spaces in parallel with the political, economic and social environments of the communities, translate the society and its organic sphere of informational performance. The information transposes a cyclical and essential role for the arrangement of the effective and necessary record to the organizational process and the institutional growth. Studies of this nature contribute to value a economy based on knowledge, and its production emphasizes the human capital that permeates the condition of the information in support for the development of communities and the growth of the organizational environment in political, social and cultural spheres.

On the undamped free vibration of a mass interacting with a Hertzian contact stiffness

Three methods are used to determine the natural frequency of undamped free vibration of a mass interacting with a Hertzian contact stiffness. The exact value is determined using the first integral of motion. The harmonic balance method is used on a transformed equation for an approximate solution, and the multiple scales method is used on an approximate equation. The maximum initial displacement avoiding contact loss is also determined, and the corresponding exact natural frequency is also obtained analytically. The methods are evaluated by studying the free vibration of an elastic sphere on a flat rigid surface. © 2011 Elsevier Ltd © 2011 Elsevier Ltd. All rights reserved.

The United Nations and ECLAC at the half-century mark of the Organization

Includes bibliography

The State, the community and society in social development

President Cardoso delivered this address at the First Regional Conference in Follow-up to the World Summit for Social Development, held in Sao Paulo from 6 to 9 April 1997. On that occasion President Cardoso reviewed the issues examined at the World Summit, with special emphasis on poverty and the search for an environmentally sound, democratic form of development that will lead to a greater degree of social equity. Within this context, he discussed the relationship between economic and social factors, devoting particular attention to State reform, education, competitiveness and job creation. He also outlined the situation in Brazil with regard to economic development, education and health services, the neeed for agrarian reform based on the principle of equity, and respect for human rights. In concluding his statement, he stressed the need to overcome the traditional division between community and society and between the public and private spheres. To that end, he called for a re-examination of ethical considerations, not as an empty discussion of morality but rather as an effective means of motivating action for change.

The relations between different levels of government in Brazil

Includes bibliography

Ten theses concerning social conflict in Latin America

Includes bibliography

Structural change and productivity growth 20 years later: old problems, new opportunities. Summary

Includes bibliography

Osteogenesis-inducing calcium phosphate nanoparticle precursors applied to titanium surfaces

This study investigated the effects of the morphology and physicochemical properties of calcium phosphate (CaP) nanoparticles on osteogenesis. Two types of CaP nanoparticles were compared, namely amorphous calcium phosphate (ACP) nano-spheres (diameter: 9-13 nm) and poorly crystalline apatite (PCA) nano-needles (30-50 nm x 2-4 nm) that closely resemble bone apatite. CaP particles were spin-coated onto titanium discs and implants; they were evaluated in cultured mouse calvarial osteoblasts, as well as after implantation in rabbit femurs. A significant dependence of CaP coatings was observed in osteoblast-related gene expression (Runx2, Col1a1 and Spp1). Specifically, the PCA group presented an up-regulation of the osteospecific genes, while the ACP group suppressed the Runx2 and Col1a1 expression when compared to blank titanium substrates. Both the ACP and PCA groups presented a more than three-fold increase of calcium deposition, as suggested by Alizarin red staining. The removal torque results implied a slight tendency in favour of the PCA group. Different forms of CaP nanostructures presented different biologic differences; the obtained information can be used to optimize surface coatings on biomaterials. © 2013 IOP Publishing Ltd.

A method for improving the code rate and error correction capability of a cyclic code

Currently, there has been an increasing demand for operational and trustworthy digital data transmission and storage systems. This demand has been augmented by the appearance of large-scale, high-speed data networks for the exchange, processing and storage of digital information in the different spheres. In this paper, we explore a way to achieve this goal. For given positive integers n,r, we establish that corresponding to a binary cyclic code C0[n,n-r], there is a binary cyclic code C[(n+1)3k-1,(n+1)3k-1-3kr], where k is a nonnegative integer, which plays a role in enhancing code rate and error correction capability. In the given scheme, the new code C is in fact responsible to carry data transmitted by C0. Consequently, a codeword of the code C0 can be encoded by the generator matrix of C and therefore this arrangement for transferring data offers a safe and swift mode. © 2013 SBMAC - Sociedade Brasileira de Matemática Aplicada e Computacional.

Visualização de Afinidades Entre Parlamentares Mediante Dados de Votações no Senado Brasileiro

The expansion of citizen participation in the public sphere depends directly of access information on the performance of elected representatives, especially with regard to their voting decisions during their terms. The Information Science can assist in this process, proposing and evaluating models of access to such information that may be obtained from data to be provided by the official websites from legislative, in levels federal, state and municipal. It is proposed in this paper to analyze the process of collecting and using of data about votes of senators in order to promote the use of this model in other spheres. From analyzed data a affinity matrix was developed to identifying the relationship between each of the parliamentary with others, based on the similarities of the decisions taken in all the open votes. It was also analyzed the development of initial visualizations and the extension of the scope of the search through the application of data obtained in all the affinities between parliamentarians and to obtain an average affinity between parties, enabling new dimensions of analysis to the data collected. The preparation of the full matrix of relations of affinity among parliamentarians can provide a new horizon of possibilities for developing new forms of visualization and analysis, increasing the visibility of parliamentary actions with society.

Roads towards gender equity in Latin America and the Caribbean

Includes bibliography