The Cariris Velhos tectonic event in Northeast Brazil

The Borborema Province in northeastern South America is a typical Brasiliano-Pan-African branching system of Neoproterozoic orogens that forms part of the Western Gondwana assembly. The province is positioned between the Sao Luis-West Africa craton to the north and the Sao Francisco (Congo-Kasai) craton to the south. For this province the main characteristics are (a) its subdivision into five major tectonic domains, bounded mostly by long shear zones, as follows: Medio Coreau, Ceara Central, Rio Grande do Norte, Transversal, and Southern; (b) the alternation of supracrustal belts with reworked basement inliers (Archean nuclei + Paleoproterozoic belts); and (c) the diversity of granitic plutonism, from Neoproterozoic to Early Cambrian ages, that affect supracrustal rocks as well as basement inliers. Recently, orogenic rock assemblages of early Tonian (1000-920 Ma) orogenic evolution have been recognized, which are restricted to the Transversal and Southern domains of the Province. Within the Transversal Zone, the Alto Pajeu terrane locally includes some remnants of oceanic crust along with island arc and continental arc rock assemblages, but the dominant supracrustal rocks are mature and immature pelitic metasedimentary and metavolcaniclastic rocks. Contiguous and parallel to the Alto Pajeu terrane, the Riacho Gravata subterrane consists mainly of low-grade metamorphic successions of metarhythmites, some of which are clearly turbiditic in origin, metaconglomerates, and sporadic marbles, along with interbedded metarhyolitic and metadacitic volcanic or metavolcaniclastic rocks. Both terrane and subterrane are cut by syn-contractional intrusive sheets of dominantly peraluminous high-K calc-alkaline, granititic to granodioritic metaplutonic rocks. The geochemical patterns of both supracrustal and intrusive rocks show similarities with associations of mature continental arc volcano-sedimentary sequences, but some subordinate intra-plate characteristics are also found. In both the Alto Pajeu and Riacho Gravata terranes, TIMS and SHRIMP U-Pb isotopic data from zircons from both metavolcanic and metaplutonic rocks yield ages between 1.0 and 0.92 Ga, which define the time span for an event of orogenic character, the Cariris Velhos event. Less extensive occurrences of rocks of Cariris Velhos age are recognized mainly in the southernmost domains of the Province, as for example in the Polo Redondo-Maranco terrane, where arc-affinity migmatite-granitic and meta-volcano-sedimentary rocks show U-Pb ages (SHRIMP data) around 0.98-0.97 Ga. For all these domains, Sm-Nd data exhibit Tom model ages between 1.9 and 1.1 Ga with corresponding slightly negative to slightly positive epsilon(Nd)(t) values. These domains, along with the Borborema Province as a whole, were significantly affected by tectonic and magmatic events of the Brasiliano Cycle (0.7-0.5 Ga), so that it is possible that there are some other early Tonian rock assemblages which were completely masked and hidden by these later Brasiliano events. Cariris Velhos processes are younger than the majority of orogenic systems at the end of Mesoproterozoic Era and beginning of Neoproterozoic throughout the world, e.g. Irumide belt, Kibaride belt and Namaqua-Natal belt, and considerably younger than those of the youngest orogenic process (Ottawan) in the Grenvillian System. Therefore, they were probably not associated with the proposed assembly of Rodinia. We suggest, instead, that Cariris Velhos magmatism and tectonism could have been related to a continental margin magmatic arc, with possible back-arc associations, and that this margin may have been a short-lived (<100 m.y.) leading edge of the newly assembled Rodinia supercontinent. (C) 2009 Elsevier Ltd. All rights reserved.

Filmes finos dielétricos para dispositivos microeletrônicos avançados

Apresentamos mecanismos de formação e de degradação térmica de filmes fi- nos (espessura da ordem de 10 nm) de diferentes dielétricos sobre substrato de silício monocristalino. Tendo em vista a aplicação dessas estruturas em MOSFETs (transistores de efeito de campo metal-óxido-semicondutor), estudamos o consagrado óxido de silício (SiO2), os atuais substitutos oxinitretos de silício (SiOxNy) e o possível substituto futuro óxido de alumínio (Al2O3). Nossos resultados experimentais baseiam-se em técnicas preparativas de substituição isotópica e de caracterização física com feixes de íons (análise com reações nucleares) ou raios- X (espectroscopia de fotoelétrons). Observamos que: (a) átomos de silício não apresentam difusão de longo alcance (além de ~ 2 nm) durante o crescimento de SiO2 por oxidação térmica do silício em O2; (b) nitretação hipertérmica é capaz de produzir filmes finos de oxinitreto de silício com até dez vezes mais nitrogênio que o resultante do processamento térmico usual, sendo que esse nitrogênio tende a se acumular na interface SiOxNy/Si; e (c) átomos de oxigênio, alumínio e silício migram e promovem reações químicas durante o recozimento térmico de estruturas Al2O3/SiO2/Si em presença de O2. Desenvolvemos um modelo de difusão-reação que poderá vir a permitir o estabelecimento de condições ótimas de processamento térmico para filmes finos de Al2O3 sobre silício a serem empregados na fabricação de MOSFETs.

Estudo do efeito da adição da escória de aciaria no processamento e propriedades finais de telhas cerâmicas

This research presents an overview of the addition steelwork dust of ceramic shingles in order to contribute to the utilization use of such residue. The ceramic industry perspective in the Brazilian State of Piauí is quite promising. Unlike other productive sectors, the ceramic industry uses basically natural raw materials. Its final products are, in short, the result of transforming clay compounds. These raw materials are composed primarily of aluminum oxide, silicon, iron, sodium, magnesium, end calcium, among others. It was verified that steelwork dust is composed primarily of these same oxides, so that its incorporation in to structural ceramics is a very reasonable idea. Both clay and steelwork powder were characterized by AG, XRF, XRD, TGA and DTA. In addition, steelwork dust samples containing (0%, 5%, 10%, 15%, 20% and 25%) were extruded and burned at 800°C, 850°C, 900°C and 950°C. Then t echnological tests of linear shrinkage, water uptake, apparent porosity, apparent density and flexural strengthwere carried at. The results showed the possibility of using steelwork powder in ceramic shingles until 15% significant improvement in physical and mechanical properties. This behavior shows the possibility of burning at temperatures lower than 850ºC, thus promoting a product final cost reduction

Evaluation of the Integrity of Horse Hoof Dermal and Epidermal Tissues Collected by Dorsal Transmural Access

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Adição de chamote de velas de ignição inservíveis na obtenção de cerâmica branca a base de alumina

This work presents research into the addition of chamotte obtained from the ceramic isolator of unusable spark plugs in formulations of material mixes for standard white ceramic material with aluminum oxide bases. After the physical chemical characterization of the primary materials, standard clay and the chamotte, three mixtures were prepared with concentrations of 10, 20 and 30% chamotte by weight in relation to the standard clay. The test samples underwent heating at a rate of 30 0C/min to levels that included 100o , 200o , 300o, 400o, 500o e 600 0C and also we submitted to three distinct burn temperatures: 1450o, 1500o e 1550 0C, remaining at these temperatures for 2 hour periods. After sintering, the physical and microstructural properties of the different test samples were measured and analyzed. The results show that the materials obtained present good technical properties and that the chamotte can be reutilized as an additive in the production of white ceramic material with an aluminum oxide base

Tensão superficial dinâmica e ângulo de contato de soluções aquosas com surfatantes em superfícies artificiais e naturais

O trabalho objetivou avaliar o efeito de surfatantes em soluções aquosas sobre a tensão superficial dinâmica e ângulo de contato das gotas em diferentes superfícies: artificiais (lâmina de vidro e de óxido de alumínio) e naturais (superfícies adaxiais de folhas de Euphorbia heterophylla, Ipomoea grandifolia e Brachiaria plantaginea). Seis formulações de surfatantes (Antideriva®; Uno®; Pronto 3®; Li-700®; Supersil® e Silwet L-77®), respectivamente nas doses recomendadas do produto comercial (0,050; 0,025; 0,100; 0,250; 0,100 e 0,100 % v v-1) e o dobro delas, foram avaliadas em soluções aquosas. A tensão superficial dinâmica e o ângulo de contato formado sobre as superfícies naturais foram medidos por tensiômetro. Os ângulos de contato formados pelas gotas nas superfícies artificiais foram obtidos por análise de imagens capturadas por uma câmera digital. Os surfatantes influenciam nas propriedades físico-químicas de soluções aquosas. As soluções contendo os surfatantes Silwet L-77® e Supersil®; nas doses de 0,100 e 0,200% v v-1; proporcionaram maiores reduções na tensão superficial dinâmica e menores ângulos de contato das gotas sobre as superfícies artificiais e naturais. Os surfatantes organossiliconados em solução aquosa foram mais eficientes na redução da tensão superficial e proporcionaram maior molhamento de superfícies natural e artificial. em alvos naturais, essas propriedades obtidas com organossiliconados são dependentes das características de superfície das espécies vegetais.

Mecanismos de alojamento de magmas granitóides :exemplo do plúton de Japi(RN)

This dissertation describes the igneous suites of the Japi granitoid pluton, intrusive in the Paleoproterozoic gneiss-migmatite complex of the eastern domain of the Seridó Belt, northeastern Brazil. Field relations show that the pluton is affected by strong deformation associated to the Brasiliano orogeny (known as the D3 phase) , with a NW-trending extensionalleft-hand senestral shear zone (the Japi Shear Zone, JSZ) bordering the intrusive body to the west. Four plutonic suites are found in the main pluton and as satellyte intrusions, besides Iate pegmatite and pink leucogranites. An alkaline granitoid suite, dominated by syenogranites bearing sodic augite (and subordinate hornblende), define a main elliptical intrusion. In its northern part, this intrusion is made up by concentric sheets, contrasting with a smaller rounded stock to the south. These granites display a pervasive solid-state S>L fabric developed under high T conditions, characterized by plastic deformation of quartz and feldspar. It is especially, developed along the border of the pluton, with inward dips. A regular magmatic layering is present sometimes, parallel to the tectonic foliation. The syntectonic emplacement as regards to the Brasiliano (D3) event is indicated by the common occurrence of dykes and sheets along transtensional or extensional sites of the major structure. Field relations attest to the early emplacement of the alkaline granites as regards to the other suites. A basic-to-intermediate suite occurs as a western satellyte body and occupying the southern tail of the main alkaline pluton. It comprises a wide variety of compositional terms, including primitive gabbros and gabbro-norites, differentiated to monzonitic intermediate facies containing amphibole and biotite as their main mafic phases. These rocks display transitional high-K calc-alkaline to shoshonitic affinities. Porphyritic monzogranite suítes commonly occur as dykes and minor intrusives, isolated or associated with the basic-tointermediate rocks. In the latter case, magma mingling and mixing features attest that these are contemporaneous igneous suites. These granites show K-feldspar phenocrysts and a hornblende+biotite+titanite assemblage, displaying subalkaline/monzonitic geochemical affinities. Both suites exhibit SL magmatic fabrics overprinting or transitional to solid-state D3 deformation related to the JSI. Chemical data clearly show that they are related to different parental magmas. Finally, a microgranite suite occurs along a few topographic ridges paralell to the JSI. It comprises dominantly granodiorites with a mineralogy similar to the one of the porphyritic granitoids. However, discriminant diagrams show their distinct calc-alkaline affinity. The granodiorites display an essencially magmatic fabric, even though an incipient D3 solid-state structure may be developed along the JSI. Intrusion relationships with the previous suites, as well as regards to the D3 structures, point to their Iate emplacement. All these suites are intrusive in a Paleoproterozoic, high-grade gneiss-migmatite complex affected by two previous deformation phases (D1, D2). The fabrics associated with these earlier events are folded and overprinted by the younger D3 structures along the JSZ. The younger deformation is characterized by NE-dipping foliations and N/NE-plunging stretching lineations. In the JSZ northern termination the foliation acquires an ENE orientation, containing a stretching lineation plunging to the south. Symmetric kinematic cri teria developed at this site confirms the transpressional termination of the JSZ, as also shown by orthorrombic quartz c-axis patterns. E-W-trending d extra I shear zones developed in the central part of the JSZ are interpreted as antithetic structures associated to the transtensional deformation along the JSZ. This is consistent with its extensional-transcurrent kinematics and a flat-and-ramp geometry at depth, as shown by gravimetric data. The lateral displacement of the negative residual Bouguer anomalies, as regards to the main outcropping alkaline pluton, may be modelized by other deeper-seated granite bodies. Based on numerical modelling it was possible to infer two distinct intrusion styles for the alkaline pluton. The calculated model values are consistent with an emplacement by sheeting for the northern body, as already suggested by satellyte imagery and field mapping. On the other hand, the results point to a transition towards a diapir-related style associated to the smaller. southern stock. This difference in intrusion styles may relate to intensity variations and transtensional sites of the shear deformation along the JSZ. Trace element and Sr and Nd isotopes of the alkaline granites are compatible with their derivation trom a more basic crustal source, as compared to the presently outcropping highgrade gneisses, with participation (or alternatively dominated by) of an enriched lithospheric mantle component. Like other igneous suites in the Seridó Belt, the high LlL contents and fractionated REE patterns of the basic rocks also point to an enriched mantle as the source for this kind of magmatism. Geochemical and isotope data are compatible with a lower crustal origin for the porphyritic granites. On the basis of the strong control of the JSZ on the emplacement of lower crustal (porphyritic and alkaline granites) or lithospheric mantle (basic rocks, alkaline granites or a component of them) magmas, one may infer a deep root for this structure, bearing an important role in magma extraction, transport and emplacement in the Japi region, eastern domain of the Seridó Belt

Petrologia do plúton Serra da Macambira, neoproterozóico da faixa seridó, província Borborema (NE do Brasil)

The final stage of Brasiliano/Pan-African orogeny in the Borborema Province is marked by widespread plutonic magmatism. The Serra da Macambira Pluton is an example of such plutonism in Seridó Belt, northeastern Borborema Province, and it is here subject of geological, petrographic, textural, geochemical and petrogenetic studies. The pluton is located in the State of Rio Grande do Norte, intrusive into Paleoproterozoic orthogneisses of the Caicó Complex and Neoproterozoic metassupracrustal rocks of the Seridó Group. Based upon intrusion/inclusion field relationships, mineralogy and texture, the rocks are classified as follows: intermediate enclaves (quartz-bearing monzonite and biotite-bearing tonalite), porphyritic monzogranite, equigranular syenogranite to monzogranite, and late granite and pegmatite dykes. Porphyritic granites and quartz-bearing monzonites represent mingling formed by the injection of an intermediate magma into a granitic one, which had already started crystallization. Both rocks are slightly older than the equigranular granites. Quartz-bearing monzonite has K-feldspar, plagioclase, biotite, hornblende and few quartz, meanwhile biotite-bearing tonalite are rich in quartz, poor in K-feldspar and hornblende is absent. Porphyritic and equigranular granites display mainly biotite and rare hornblende, myrmekite and pertitic textures, and zoned plagioclase pointing out to the relevance of fractional crystallization during magma evolution. Such granites have Rare Earth Elements (REE) pattern with negative Eu anomaly and light REE enrichment when compared to heavy REE. They are slight metaluminous to slight peraluminous, following a high-K calc-alkaline path. Petrogenesis started with 27,5% partial melting of Paleoproterozoic continental crust, generating an acid hydrous liquid, leaving a granulitic residue with orthopyroxene, plagioclase (An40-50), K-feldspar, quartz, epidote, magnetite, ilmenite, apatite and zircon. The liquid evolved mainly by fractional crystallization (10-25%) of plagioclase (An20), biotite and hornblende during the first stages of magmatic evolution. Granitic dykes are hololeucocratic with granophyric texture, indicating hypabissal crystallization and REE patterns similar to A-Type granites. Preserved igneous textures, absence or weak imprint of ductile tectonics, association with mafic to intermediate enclaves and alignment of samples according to monzonitic (high-K calcalkaline) series all indicate post-collisional to post-orogenic complexes as described in the literature. Such interpretation is supported by trace element discrimination diagrams that place the Serra da Macambira pluton as late-orogenic, probably reflecting the vanishing stages of the exhumation and collapse of the Brasiliano/Pan-African orogen.

Prosthetic transfer impression accuracy evaluation for osseointegrated implants

Purpose: The objective of this study was to evaluate and compare 3 impression techniques for osseointegrated implant transfer procedures.Materials and Methods: (1) Group Splinted with Acrylic Resin (SAR), impression with square copings splinted with prefabricated autopolymerizing acrylic resin bar; (2) Group Splinted with Light-Curing Resin (SLR), impression, with square copings splinted with prefabricated light-curing composite resin bar; (3). Group Independent Air-abraded (IAA), impression with independent square coping aluminum oxide air-abraded. Impression procedures were performed with polyether material, and the data obtained was compared with a control group. These were characterized by metal matrix (MM) measurement values of the implants inclination positions at 90 and 05 degrees in relation to the matrix surface. Readings of analogs and implant inclinations were assessed randomly through graphic computation AutoCAD software. Experimental groups angular deviation with MM were submitted to analysis of variance and means were compared through Tukey's test (P < 0.05).Results: There was no statistical significant difference between SAR and SLR experimental groups and MM for vertical and angulated implants. Group IAA presented a statistically significant difference for angulated implants.Conclusion: It was concluded within the limitations of this study, that SAR and SLR produced more accurate casts than IAA technique, which presented inferior results.

Avaliação do Índice de Remanescente Adesivo utilizando braquetes com e sem tratamento na base e a interação com três sistemas de colagem

OBJETIVO: avaliar o Índice de Remanescente Adesivo (IRA) em dentes bovinos após a descolagem de braquetes com e sem tratamento na base. METODOLOGIA: foram utilizados três sistemas de colagem ortodôntica para os dois padrões de base. Os dentes bovinos foram divididos em seis grupos de 40, de acordo com a base do braquete e o sistema de colagem. Vinte e quatro horas após a colagem foram realizados os testes de compressão em uma máquina de ensaios. A avaliação do IRA foi realizada em um estereomicroscópio por três examinadores calibrados. Foi utilizado o teste não paramétrico de Kruskal-Wallis, seguido do método de Dunn, para fazer as comparações múltiplas entre todos os grupos. RESULTADOS E CONCLUSÕES: observou-se que o tratamento das bases dos braquetes com óxido de alumínio não foi determinante para o aumento da adesividade entre o braquete e o adesivo. O grupo em que se utilizou braquetes com tratamento na base e adesivo TXT (3M-Unitek) + Transbond Plus SEP (3M-Unitek) apresentou a maior parte das fraturas na interface dente-adesivo (escore 4).

In vitro evaluation of the influence of air abrasion on detection of occlusal caries lesions in primary teeth

Purpose: The purpose of this study was to assess the influence of cleaning pits and fissures with on aluminum oxide air abrasion system on the detection of occlusal caries in primary teeth using laser fluorescence (LF) and visual examination. Methods. The sample comprised 65 pit and fissure sites on extracted primary teeth suspected to be carious. The sites were submitted to 2 visual examinations (examiner JAR) and 2 LF readings (examiner TMV). Next, the occlusal surfaces were air-abraded and re-examined thereafter using both methods. The teeth were sectioned, and the histological analysis of the sites with a stereoscopic magnifying lens at X32 magnification was used as the gold standard Results. Cohen's kappa statistic for LF and visual examination were, respectively, 0.282/0.884 before and 0.896/0.905 after air abrasion. LF showed a sensitivity of 0.28 increasing to 0.49 and 0 specificity of 0.50 increasing to 0.92. Visual examination showed sensitivity of 0.78 and specificity of 0.73. Both increased after air abrasion. Conclusion: The findings suggest that cleaning pits and fissures with aluminum oxide air abrasion increased the accuracy of LF and visual examination for detection of occlusal caries in primary teeth.

Effect of metal conditioners on the adhesive bonding of resin cements to cast titanium

Objective: To assess the effect of metal conditioners on the bond strength between resin cements and cast titanium. Method and Materials: Commercially pure titanium (99.56%) was cast using an arc casting machine. Surfaces were finished with 400-grit silicon carbide paper followed by air abrasion with 50-mu m aluminum oxide. A piece of double-coated tape with a 4-mm circular hole was then positioned on the metal surface to control the area of the bond. The prepared surfaces were then divided into 4 groups (n=10): G1, unprimed Panavia F; G2, Alloy Primer-Panavia F; G3, unprimed Bistite DC; G4, Metaltite-Bistite DC. Forty minutes after insertion of the resin cements, the specimens were detached from the mold and stored in water at 37 C for 24 hours. Shear bond strength was performed in a testing machine (MTS 810) at a crosshead speed of 0.5 mm/min. Data were analyzed using ANOVA and Tukey's test with a .05 significance level. The fractured surfaces were observed through an optical microscope at 10x magnification. Results: the G1 group demonstrated significantly higher shear bond strength (17.95 MPa) than the other groups. G3 (13.79 MPa) and G4 (12.98 MPa) showed similar mean values to each other and were statistically superior to G2 (9.31 MPa). Debonded surfaces generally presented adhesive failure between metal surfaces and resin cements. Conclusion: While the Metaltite conditioner did not influence the bond strength of the Bistite DC cement, the Alloy Primer conditioner significantly decreased the mean bond strength of the Panavia F cement.

EFFECT of METAL PRIMERS on BOND STRENGTH of RESIN CEMENTS TO BASE METALS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of Er:YAG laser on surface treatment of aged composite resin to repair restoration

The purpose of this study was to investigate the effect of Er:YAG laser on surface treatment to the bond strength of repaired composite resin after aged. Sixty specimens (n = 10) were made with composite resin (Z250, 3M) and thermocycled with 500 cycles, oscillating between 5 to 55A degrees C. The specimens were randomly separated in six groups which suffered the following superficial treatments: no treatment (GI, control), wearing with diamond bur (GII), sandblasted with aluminum oxide with 27.5 A mu m particles (GIII) for 10 s, 200 mJ Er:YAG laser (GIV), 300 mJ Er:YAG laser (GV), and 400 mJ Er:YAG laser (GVI), with the last 3 groups under a 10 Hz frequency for 10 s. Restoration repair was done using the same composite. The shear test was done into the Universal testing machine MTS-810. Analyzing the results through ANOVA and Tukey test, no significant differences were found (p-value is 0.5120). Average values analysis showed that superficial treatment with aluminum oxide presented the highest resistance to shear repair interface (8.91MPa) while 400 mJ Er:YAG laser presented the lowest (6.76 MPa). Fracture types analysis revealed that 90% suffered cohesive fractures to GIII. The Er:YAG laser used as superficial treatment of the aged composite resin before the repair showed similar results when used diamond bur and sandblasting with aluminum oxide particles.

Streptococcus mutans Biofilm Adhesion on Composite Resin Surfaces After Different Finishing and Polishing Techniques

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)