Óxidos de ferro magnéticos de um tufito da região do Alto Paranaíba, MG

The Mössbauer analysis along with the structural Rietveld refinement based on powder X-ray data for the magnetic fraction (saturation magnetization, sigma = 19 J T-1 kg-1) separated from a tuffite material from Alto Paranaíba, state of Minas Gerais, Brazil, reveal that a (Ti, Mg)-rich maghemite (deduced sigma = 17 J T-1 kg-1) and, for the first time observed in this lithodomain, magnesioferrite (characteristic sigma = 21 J T-1 kg-1) respond for the magnetization of the rock material. Consistent models for the ionic distribution in these iron-rich spinel structures are proposed.

Síntese hidrotermal assistida por micro-ondas como metodologia sintética eficiente para obtenção da rede metalorgânica [ZN(BDC)(H2O)2]n

This work presents the optimization of the microwave-assisted hydrothermal synthesis of [Zn(BDC)(H2O)2]n . The reactions were carried out at the fixed temperature of 120 ºC for 10, 20, 30 and 40 min. Pure crystalline [Zn(BDC)(H2O)2]n was obtained in high yield (ca. 90%) with a reaction time of 10 min. The phase obtained and its purity was confirmed by Rietveld refinement, with a final value for Rwp/Rexp equal to 1.48. Increased reaction times (20, 30 and 40 min) favored the formation of unwanted by products, resulting in mixtures of several crystalline phases.

Comparação estrutural entre amostras de materiais tipo hidrotalcita obtidas a partir de diferentes rotas de síntese

Three samples of hydrotalcite-like materials (HTC) were synthesized and their structural characteristics were compared with two HTCs obtained commercially. Thermal analyses, FT-IR, PXRD and textural analyses were used to investigate the structural differences between commercial and synthetic samples. Particularly, the memory effect was observed at temperature higher than 600 ºC. The Rietveld refinements were obtained with expressive accuracy and the statistical parameters of goodness of fit are quite satisfactory. In conclusion, the procedures adopted in synthesis of HTC produced crystalline materials with high surface area materials.

The role of discriminant analysis in the refinement of customer satisfaction assessment

OBJECTIVE: To test discriminant analysis as a method of turning the information of a routine customer satisfaction survey (CSS) into a more accurate decision-making tool. METHODS: A 7-question, 10-multiple choice, self-applied questionnaire was used to study a sample of patients seen in two outpatient care units in Valparaíso, Chile, one of primary care (n=100) and the other of secondary care (n=249). Two cutting points were considered in the dependent variable (final satisfaction score): satisfied versus unsatisfied, and very satisfied versus all others. Results were compared with empirical measures (proportion of satisfied individuals, proportion of unsatisfied individuals and size of the median). RESULTS: The response rate was very high, over 97.0% in both units. A new variable, medical attention, was revealed, as explaining satisfaction at the primary care unit. The proportion of the total variability explained by the model was very high (over 99.4%) in both units, when comparing satisfied with unsatisfied customers. In the analysis of very satisfied versus all other customers, significant relationship was identified only in the case of the primary care unit, which explained a small proportion of the variability (41.9%). CONCLUSIONS: Discriminant analysis identified relationships not revealed by the previous analysis. It provided information about the proportion of the variability explained by the model. It identified non-significant relationships suggested by empirical analysis (e.g. the case of the relation very satisfied versus others in the secondary care unit). It measured the contribution of each independent variable to the explanation of the variation of the dependent one.

USE AND CONSEQUENCES OF PARTICIPATORY GIS IN A MEXICAN MUNICIPALITY: APPLYING A MULTILEVEL FRAMEWORK

This paper seeks to understand the use and the consequences of Participatory Geographic Information System (PGIS) in a Mexican local community. A multilevel framework was applied, mainly influenced by two theoretical lenses – structurationist view and social shaping of technology – structured in three dimensions – context, process and content – according to contextualist logic. The results of our study have brought two main contributions. The first is the refinement of the theoretical framework in order to better investigate the implementation and use of Information and Communication Technology (ICT) artifacts by local communities for social and environmental purposes. The second contribution is the extension of existing IS (Information Systems) literature on participatory practices through identification of important conditions for helping the mobilization of ICT as a tool for empowering local communities.

O planejamento econômico no Brasil: considerações críticas

In the past thirty years, a series of plans have been developed by successive Brazilian governments in a continuing effort to maximize the nation's resources for economic and social growth. This planning history has been quantitatively rich but qualitatively poor. The disjunction has stimulated Professor Mello e Souza to address himself to the problem of national planning and to offer some criticisms of Brazilian planning experience. Though political instability has obviously been a factor promoting discontinuity, his criticisms are aimed at the attitudes and strategic concepts which have sought to link planning to national goals and administration. He criticizes the fascination with techniques and plans to the exclusion of proper diagnosis of the socio-political reality, developing instruments to coordinate and carry out objectives, and creating an administrative structure centralized enough to make national decisions and decentralized enough to perform on the basis of those decisions. Thus, fixed, quantified objectives abound while the problem of functioning mechanisms for the coordinated, rational use of resources has been left unattended. Although his interest and criticism are focused on the process and experience of national planning, he recognized variation in the level and results of Brazilian planning. National plans have failed due to faulty conception of the function of planning. Sectorial plans, save in the sector of the petroleum industry under government responsibility, ha e not succeeded in overcoming the problems of formulation and execution thereby repeating old technical errors. Planning for the private sector has a somewhat brighter history due to the use of Grupos Executivos which has enabled the planning process to transcend the formalism and tradition-bound attitudes of the regular bureaucracy. Regional planning offers two relatively successful experiences, Sudene and the strategy of the regionally oriented autarchy. Thus, planning history in Brazil is not entirely black but a certain shade of grey. The major part of the article, however, is devoted to a descriptive analysis of the national planning experience. The plans included in this analysis are: The Works and Equipment Plan (POE); The Health, Food, Transportation and Energy Plan (Salte); The Program of Goals; The Trienal Plan of Economic and Social Development; and the Plan of Governmental Economic Action (Paeg). Using these five plans for his historical experience the author sets out a series of errors of formulation and execution by which he analyzes that experience. With respect to formulation, he speaks of a lack of elaboration of programs and projects, of coordination among diverse goals, and of provision of qualified staff and techniques. He mentions the absence of the definition of resources necessary to the financing of the plan and the inadequate quantification of sectorial and national goals due to the lack of reliable statistical information. Finally, he notes the failure to coordinate the annual budget with the multi-year plans. He sees the problems of execution as beginning in the absence of coordination between the various sectors of the public administration, the failure to develop an operative system of decentralization, the absence of any system of financial and fiscal control over execution, the difficulties imposed by the system of public accounting, and the absence of an adequate program of allocation for the liberation of resources. He ends by pointing to the failure to develop and use an integrated system of political economic tools in a mode compatible with the objective of the plans. The body of the article analyzes national planning experience in Brazil using these lists of errors as rough model of criticism. Several conclusions emerge from this analysis with regard to planning in Brazil and in developing countries, in general. Plans have generally been of little avail in Brazil because of the lack of a continuous, bureaucratized (in the Weberian sense) planning organization set in an instrumentally suitable administrative structure and based on thorough diagnoses of socio-economic conditions and problems. Plans have become the justification for planning. Planning has come to be conceived as a rational method of orienting the process of decisions through the establishment of a precise and quantified relation between means and ends. But this conception has led to a planning history rimmed with frustration, and failure, because of its rigidity in the face of flexible and changing reality. Rather, he suggests a conception of planning which understands it "as a rational process of formulating decisions about the policy, economy, and society whose only demand is that of managing the instrumentarium in a harmonious and integrated form in order to reach explicit, but not quantified ends". He calls this "planning without plans": the establishment of broad-scale tendencies through diagnosis whose implementation is carried out through an adjustable, coherent instrumentarium of political-economic tools. Administration according to a plan of multiple, integrated goals is a sound procedure if the nation's administrative machinery contains the technical development needed to control the multiple variables linked to any situation of socio-economic change. Brazil does not possess this level of refinement and any strategy of planning relevant to its problems must recognize this. The reforms which have been attempted fail to make this recognition as is true of the conception of planning informing the Brazilian experience. Therefore, unworkable plans, ill-diagnosed with little or no supportive instrumentarium or flexibility have been Brazil's legacy. This legacy seems likely to continue until the conception of planning comes to live in the reality of Brazil.

Future trypanosomatid phylogenies: refined homologies, supertrees and networks

There has been good progress in inferring the evolutionary relationships within trypanosomes from DNA data as until relatively recently, many relationships have remained rather speculative. Ongoing molecular studies have provided data that have adequately shown Trypanosoma to be monophyletic and, rather surprisingly, that there are sharply contrasting levels of genetic variation within and between the major trypanosomatid groups. There are still, however, areas of research that could benefit from further development and resolution that broadly fall upon three questions. Are the current statements of evolutionary homology within ribosomal small sub-unit genes in need of refinement? Can the published phylograms be expanded upon to form `supertrees' depicting further relationships? Does a bifurcating tree structure impose an untenable dogma upon trypanosomatid phylogeny where hybridisation or reticulate evolutionary steps have played a part? This article briefly addresses these three questions and, in so doing, hopes to stimulate further interest in the molecular evolution of the group.

Immunogenicity test of tetanus component in adsorbed vaccines by toxin binding inhibition test

Samples from 20 lots of diphtheria-tetanus (adult use dT) vaccine and from 20 lots of diphtheria-tetanus-pertussis (DTP) vaccine were used to standardize and validate the in vitro toxin binding inhibition (ToBI) test for the immunogenicity test of the tetanus component. The levels of tetanus antitoxin obtained by ToBI test were compared to those obtained using the toxin neutralization (TN) test in mice routinely employed to perform the quality control of the tetanus component in adsorbed vaccines. The results ranged from 1.8 to 3.5 IU/ml for dT and 2 to 4 IU/ml for DTP by ToBI test and 1.4 to 3 IU/ml for dT and 1.8 to 3.5 IU/ml for DTP by TN in mice. These results were significantly correlated. From this study, it is concluded that the ToBI test is an alternative to the in vivo neutralization procedure in the immunogenicity test of the tetanus component in adsorbed vaccines. A substantial refinement and a reduction in use of animals can be achieved.

Comparação de procedimentos de quantificação de caulinita e gibbsita na fração argila desferrificada de Latossolos

A acurada determinação dos teores dos minerais que constituem a fração argila dos Latossolos pode contribuir para o aprimoramento de seu uso e manejo. Neste trabalho, teores de caulinita e gibbsita da fração argila desferrificada de Latossolos foram determinados por calorimetria exploratória diferencial (CED) e pela aplicação do método de Rietveld a dados de difratometria de raios X (DRX), e comparados com seus respectivos teores calculados pelo método da alocação. Possivelmente, diferenças cristalográficas entre a caulinita e a gibbsita utilizadas na calibração da CED e suas respectivas contrapartidas encontradas nas amostras analisadas tenham contribuído para a menor exatidão dos teores de caulinita e de gibbsita determinados pelo referido método térmico. Os teores de gibbsita das argilas desferrificadas quantificados com a abordagem DRX-Rietveld foram praticamente idênticos aos calculados por alocação, ao passo que os de caulinita foram similares aos respectivos teores determinados com o método de Rietveld.

Propriedades cristalográficas de caulinitas de solos do ambiente tabuleiros costeiros, Amazônia e Recôncavo Baiano

Grande parte das propriedades e características dos solos estão relacionadas à quantidade e ao tipo de mineral na fração argila. Os objetivos deste trabalho foram caracterizar a fração argila e estudar as características cristalográficas das caulinitas de solos vermelhos e amarelos, visando ao entendimento das relações desse mineral com as características e propriedades dos solos dominantes na região dos Tabuleiros Costeiros e mais interioranos do Brasil. Para isso, determinou-se a relação argila grossa/argila fina e foram realizadas análises mineralógicas (qualitativa e quantitativa) por meio de DRX e aplicação do método Rietveld; caracterização espectral por ERD, para determinação da relação hematita/goethita; estimativa de propriedades cristalográficas (tamanho e microtensões), por DRX e utilizando modelos matemáticos; da superfície específica, por BET-N2; da fractalidade; do grau de desordem estrutural, por diversos índices; e análises de microscopia eletrônica de transmissão. Os resultados permitiram as seguintes conclusões: (a) a quantificação dos minerais de argila pelo método Rietveld revelou predomínio marcante das caulinitas em todos os solos estudados; (b) a análise dos espectros de DRX, aplicando-se o método Rietveld, sugere a coexistência de caulinitas triclínicas e caulinitas com caráter monoclínico; (c) as caulinitas menores que 0,2 µm de todos os solos foram similares em superfície específica BET-N2, dimensão média do cristalito no plano (001), grau de desordem estrutural e dimensão fractal, mas diferentes em sua morfologia, que se apresentou correlacionada com o material de origem.

Estudo arqueométrico de cerâmicas do Sítio Guará, Goiás, Brasil

There is no evidence of urban civilization in Brazilian prehistory; most inhabitants lived in tribal groupings, probably with regional economic integration among several independent tribes. There is little evidence of seasonal migrations between the coast and the inland of southern Brazil. Some specialized horticulturists competed among themselves but other groups lived more isolated and probably peacefully, in the upper interfluvial regions. Chemical analysis of artifacts is a means of documenting traffic in particular materials and intraregional production and distribution, development of craft specialization and typological refinement among other issues. In this study we tested some possibilities in two different cultural contexts using the parametric k0 neutron activation analysis technique, which allowed the determination of elements: Al, As, Au, Ce, Cl, Co, Cr, Cs, Cu, Fe, Ga, K, La, Na, Rb, Sc, Ta, Ti, V and Zn.

Propriedades estruturais e microestruturais de manganitas dopadas com cobre

We report a structural study on polycrystalline La0.86Sr0.14Mn1-y Cu yO3+delta samples (y = 0, 0.05, 0.10, 0.15, 0.20) using refinement of powder X-ray diffraction data and analysis of scanning electron microscopy images. It is found that the structure remains rhombohedral through the whole series, with a decrease in the average Mn-Mn bond distances, slight variations in Mn-O-Mn angle and reduction in the unit cell volume with increasing Cu amounts. The values of Mn-Mn distances suggest compact structures with d within ±1%. Scanning electron microscopy images reveal homogeneous microstructure in all samples, besides a trend for smaller grains and larger porosity with increasing Cu content.

Síntese da hidroxiapatita e refinamento estrutural por difração de raios-x

A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effectswith an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals.

Análise cristalográfica da solução sólida com estrutura tipo Tungstênio Bronze de niobato de potássio e estrôncio dopado com ferro

Solid solution of iron doped potassium strontium niobate with KSr2(FeNb4)O15-Δ stoichiometry was prepared by high efficiency ball milling method. Structural characterization was carried out by X-ray diffraction. Crystalline structure was analyzed by the Rietveld refinements using the FullProf software. The results showed a tetragonal system with the tetragonal tungsten bronze structure - TTB (a = 12.4631 (2) Å and c = 3.9322 (6) Å, V = 610.78 (2) ų). In this work, the sites occupancy by the K+, Sr2+ and Fe3+ cations on the TTB structure were determined. NbO6 polihedra distortion and its correlation with the theoretical polarization are discussed.

Síntese e caracterização de CaZrO3 e BaZrO3 nanoestruturados

In this work, nanostructured samples of barium zirconate (BaZrO3) and calcium zirconate (CaZrO3) were synthesized by the gel-combustion method, using glycine as fuel. The ceramic powders were calcined at 550 °C for 2 h and subsequently heat treated at 1350 °C for 10 min (fast-firing). The X-ray diffraction technique was employed to identify and characterize the crystalline phases present in the synthesized powders, using the Rietveld method. Monophasic nanostructured samples of BaZrO3 and CaZrO3 presenting average crystallite sizes of around 8.5 and 10.3 nm, respectively, were found after fast-firing.