Resposta do feijoeiro a fertilizantes fosfatados na presença e ausência de calagem

Com o objetivo de verificar a resposta do feijoeiro (Phaseolus vulgaris L.) a fontes de fósforo, na presença e na ausência de calagem, instalou-se um experimento em casa de vegetação, utilizando-se uma amostra de solo Latossolo Vermelho-Amarelo Distrófico, textura argilosa, não cultivado, do município de Viçosa, MG, no período de fevereiro a abril de 1984. O delineamento experimental foi inteiramente casualizado, sendo um fatorial 2 x 4, em nove repetições. Os tratamentos foram formados da seguinte combinação: 0 e 1 x necessidade de calagem, sem fósforo e com fósforo de três fontes: superfosfato triplo, termofosfato Yoorim e fosfato de Araxá. A colheita foi efetuada aos 45 dias após o plantio. Obtiveram-se o peso da parte aérea seca e o teor de fósforo acumulado. Pelos resultados obtidos, e nas condições em que este experimento foi conduzido, conclui-se que, na ausência de calagem, a melhor fonte fosfatada é o termofosfato, e na presença de calagem o efeito desta fonte é similar ao do superfosfato triplo.

Consolidation and break-up of the South American platform in southeastern Brazil: Tectonothermal and denudation histories

The different tectonic stages that occurred at the end of the Proterozoic and during the Phanerozoic have an important bearing on the tectonothermal history of the South American Platform and its consolidation. Geochronological data (U/Pb monazite, Ar-40/Ar-39 whole rock) and apatite fission-track analysis, from Precambrian rocks of the southeastern Brazilian coastline, permit the modeling of a long-term thermal history of the crust and constrain variable denudation rates.Using these data, a temperature-time diagram reflects a period of accelerated exhumation during the end of the Brasiliano Orogeny, followed by long stability and reactivation of the platform during the Rifting Phase of the South Atlantic Ocean.U/Pb zircon and monazite (blocking temperature of ca. 650degreesC) data from a series of igneous bodies suggest that a tangential and transpressional tectonic regime occurred between 625 and 610 Ma. During the following escape tectonics, between 610 and 590 Ma the exhumation process indicates cooling rates of ca. 12degreesC/Ma. Ar-40/Ar-39 biotite ages between 540 and 510 Ma (ca. 300degreesC) and a corrected fission-track age on apatites (100degreesC) of 480 Ma indicate an exhumation event related to block tectonics with huge vertical displacement along shear zones.A long stabilization phase, with low exhumation, and cooling rate around 0.25degreesC/Ma was recorded from the Cambro/Ordovician to the Mesozoic. At 65 Ma an acceleration of the exhumation through denudation and reworking of the South American surface with cooling rate of 1.5degreesC/Ma is observed.The uplift of the Mantiqueira and Serra do Mar mountain ranges along the southeast Brazilian coastline works as a climatic barrier provoking lateral erosional processes causing long-term scarp retreat, combined with intense, but progressive denudation towards the continent. A denudation of 2.5 to 4 km was calculated for such processes. This lateral retreat of escarpments and flexural response can provide important insights regarding marginal isostatic uplift and the evolution of offshore sedimentary basins of southeast Brazil.

Solubilização de fosfatos de rocha por Aspergillus niger em diferentes tipos de vinhaça

Aspergillus niger was inoculated into flasks containing mixed of different origins and fluorapatite as a source of phosphorus, or alternatively rock phosphates of different compositions. There was no difference in fungal growth or fluorapatite solubilization when sterilized or unsterilized vinasse was used. Total and soluble solid content was at least two times higher in 65/35 vinasse than in 10/1 vinasse. The higher total sugar content causing higher titratable acidity levels, or the lower fungal growth, may possibly have favored the greater accumulation of soluble phosphate in 10/1 than in 65/10 vinasse. No appreciable differences in residual soluble phosphate levels were detected with increasing fluorapatite concentrations. Rock phosphates of different origins and with different phosphorus concentrations affected the solubilizing ability of the fungus. Whereas crude concentrated apatite phosphorus favored the greatest accumulation of soluble phosphate in the culture medium (1.08 mg/ml), the highest solubilization (72% total phosphate) was achieved with Patos de Minas material obtained from the first crushing.

Collagen-hydroxyapatite films: piezoelectric properties

In this paper we report a study of the physicochemical, dielectric and piezoelectric properties of anionic collagen and collagen-hydroxyapatite (HA) composites, considering the development of new biomaterials which have potential applications in support for cellular growth and in systems for bone regeneration. The piezoelectric strain tensor element d(14), the elastic constant s(55) and the dielectric permittivity 8(11), were measured for the anionic collagen and collagen-HA films. The thermal analysis shows that the denaturation endotherm is at 59.47 degreesC for the collagen sample. The collagen-HA composite film shows two transitions, at 48.9 and 80.65 degreesC. The X-ray diffraction pattern of the collagen film shows a broad band characteristic of an amorphous material. The main peaks associated to the crystalline HA is present in the sample of collagen-HA. In the collagen-HA composite, one can also notice the presence of other peaks with low intensities which is an indication of the formation of other crystalline phases of apatite. The scanning electron photomicrograph of anionic collagen membranes shows very thin bundles of collagen. The scanning electron photomicrography of collagen-HA film also show deposits of hydroxyapatite on the collagen fibers forming larger bundles and suggesting that a collagenous structure of reconstituted collagen fibers could act as nucleators for the formation of apatite crystal similar to those of bone. The piezoelectric strain tensor element d(14) was measured for the anionic collagen, with a value of 0.062 pC N-1, which is in good agreement compared with values reported in the literature obtained with other techniques. For the collagen-HA composite membranes, a slight decrease of the value of the piezoelectricity (0.041 pC N-1) was observed. The anionic collagen membranes present the highest density, dielectric permittivity and lowest frequency constant f.L. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Thermotectonic and fault dynamic analysis of Precambrian basement and tectonic constraints with the Parana basin

The Precambrian crystalline basement of southeast Brazil is affected by many Phanerozoic reactivations of shear zones that developed during the end of the Neoproterozoic in the Brasiliano orogeny. These reactivations with specific tectonic events, a multidisciplinary study was done, involving geology, paleostress, and structural analysis of faults, associated with apatite fission track methods along the northeastern border of the Parana basin in southeast Brazil.The results show that the study area consists of three main tectonic domains, which record different episodes of uplift and reactivation of faults. These faults were brittle in character and resulted in multiple generations of fault products as pseudotachylytes and ultracataclasites, foliated cataclasites and fault gouges.Based on geological evidence and fission track data, an uplift of basement rocks and related tectonic subsidence with consequent deposition in the Parana basin were modeled.The reactivations of the basement record successive uplift events during the Phanerozoic dated via corrected fission track ages, at 387 +/- 50 Ma (Ordovician); 193 +/- 19 Ma (Triassic); 142 +/- 18 Ma (Jurassic), 126 +/- 11 Ma (Early Cretaceous); 89 +/- 10 Ma (Late Cretaceous) and 69 +/- 10 Ma (Late Cretaceous). These results indicate differential uplift of tectonic domains of basement units, probably related to Parana basin subsidence. Six major sedimentary units (supersequences) that have been deposited with their bounding unconformities, seem to have a close relationship with the orogenic events during the evolution of southwestern Gondwana. (c) 2005 Elsevier Ltd. All rights reserved.

Geochemistry of the Guaxupe Granulites, Minas Gerais, Brazil

Geochemical data for granulite terrain are presented from the northernmost portion of the Guaxupe Massif, at Mantiqueira Province, SE Brazil. Several types of granulites are recognized in the area: basic, intermediate and acid granulite. Major and trace elements (including REE) point to only one ma,oma source for these granulites generated at different times. Geochemical data point to plagioclase and apatite fractionation as responsable in the REE behaviour in intermediate and more basic rocks. Overall composition of the Guaxupe Granulites is similar to average composition of the lower crust.

Alumina/zirconia composite coated by biomimetic method

In this study, a bioactive zirconia-toughened alumina (ZTA) composite was developed for orthopedic applications. This composite was obtained by slip casting of suspension powder mixtures.Biomimetic processes were used to grow a bone-like apatite layer on composite substrates using sodium silicate solution as a nucleating agent and simulated body fluids. The composites, with or without coating, were characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS), and their apparent density was determined by the Archimedes method. The composites obtained by this process possessed the expected stiffness and dimensions and their density values were similar to those of the composite's theoretical density (98.8%TD). The morphology of the hydroxyapatite formed on the composite surface was homogeneous and composed of small globules, characterizing a carbonated hydroxyapatite. The results of the tests indicated that the method employed to produce the composite and its coating was efficient under the conditions of this study. (c) 2006 Elsevier B.V. All rights reserved.

Rift to post-rift evolution of a passive continental margin: the Ponta Grossa Arch, SE Brazil

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

Denudation history of the Bocaina Plateau, Serra do Mar, southeastern Brazil: Relationships to Gondwana breakup and passive margin development

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

Inorganic-Organic Nanocomposite Assembly Using Collagen as a Template and Sodium Tripolyphosphate as a Biomimetic Analog of Matrix Phosphoprotein

Nanocomposites created with polycarboxylic acid alone as a stabilization agent for prenucleation clusters-derived amorphous calcium phosphate exhibit nonperiodic apatite deposition. In the present study, we report the use of inorganic polyphosphate as a biomimetic analog of matrix phosphoprotein for directing poly(acrylic acid)-stabilized amorphous nano-precursor phases to assemble into periodic apatite-collagen nanocomposites. The sorption and desorption characteristics of sodium tripolyphosphate to type I collagen were examined. Periodic nanocomposite assembly with collagen as a template was demonstrated with TEM and SEM using a Portland cement-based resin composite and a phosphate-containing simulated body fluid. Apatite was detected within the collagen at 24 h and became more distinct at 48 h, with prenucleation clusters attaching to the collagen fibril surface during the initial infiltration stage. Apatite-collagen nanocomposites at 72 h were heavily mineralized with periodically arranged intrafibrillar apatite platelets. Defect-containing nanocomposites caused by desorption of TPP from collagen fibrils were observed in regions lacking the inorganic phase.

Bioactive coating on titanium implants modified by Nd:YVO4 laser

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Immediate replantation of maxillary incisors in rats: effects of tooth immersion in sodium fluoride and subsequent removal of the periodontal ligament.

The advantages and disadvantages of maintaining the periodontal ligament (PDL) in immediate replantation as well as chemical treatment of the root surface have been a matter of discussion because the vitality of such tissue in surgery is always questioned. This study evaluated the effects of conserving the tooth in sodium fluoride and the removal of the PDL before replantation of incisors in rats. There was more cementum-dentin resorption in the group with the PDL. The group without the PDL showed more discreet resorption, repair occurred through the newly formed bone tissue in the PDL space and ankylosis was more extensive than in the group with the PDL.

Efeito dose-resposta de uma formulação de dentifrício com concentração reduzida de fluoreto - estudo in vitro.

The utilization of dentifrices with low fluorine concentration, for children under 6 years of age, has been suggested to reduce the risks of dental fluorosis. However, in order to have anticariogenic potential, the dentifrice should form loosely-bound fluorine (CaF2) on dental enamel. Considering that the formation of CaF2 is a function inversely related to pH, dentifrices with pH 5.5, with 275, 550 and 1,100 ppm F (NaF/silica) were developed in order to assess dose-response effects. A comparison between those dentifrices, a placebo product and the Crest toothpaste (positive control - standard) was carried out. Furthermore, the bioavailability of dentifrices, in terms of formation of total fluorine (TF), CaF2, and fluorapatite (FA) on human dental enamel, was evaluated. An ion-specific electrode was utilized for the determination of the dosage of fluorine. The results revealed that the dentifrice with 550 ppm F was more effective than both the placebo and the dentifrice with 275 ppm, presenting no difference in relation to the positive control (p > 0.05). A dose-effect correlation was observed as to the CaF2 formed. In conclusion, the modified formulation with 550 ppm F can be considered as effective as the standard dentifrice with 1,100 ppm, and its utilization would be safer with regard to dental fluorosis.

U-Pb geochronology of the southern Brasília belt (SE-Brazil): Sedimentary provenance, Neoproterozoic orogeny and assembly of West Gondwana

The Brasília belt borders the western margin of the São Francisco Craton and records the history of ocean opening and closing related to the formation of West Gondwana. This study reports new U-Pb data from the southern sector of the belt in order to provide temporal limits for the deposition and ages of provenance of sediments accumulated in passive margin successions around the south and southwestern margins of the São Francisco Craton, and date the orogenic events leading to the amalgamation of West Gondwana. Ages of detrital zircons (by ID-TIMS and LA-MC-ICPMS) were obtained from metasedimentary units of the passive margin of the São Francisco Craton from the main tectonic domains of the belt: the internal allochthons (Araxá Group in the Áraxá and Passos Nappes), the external allochthons (Canastra Group, Serra da Boa Esperança Metasedimentary Sequence and Andrelândia Group) and the autochthonous or Cratonic Domain (Andrelândia Group). The patterns of provenance ages for these units are uniform and are characterised as follows: Archean- Paleoproterozoic ages (3.4-3.3, 3.1-2.7, and 2.5-2.4Ga); Paleoproterozoic ages attributed to the Transamazonian event (2.3-1.9Ga, with a peak at ca. 2.15Ga) and to the ca. 1.75Ga Espinhaço rifting of the São Francisco Craton; ages between 1.6 and 1.2Ga, with a peak at 1.3Ga, revealing an unexpected variety of Mesoproterozoic sources, still undetected in the São Francisco Craton; and ages between 0.9 and 1.0Ga related to the rifting event that led to the individualisation of the São Francisco paleo-continent and formation of its passive margins. An amphibolite intercalation in the Araxá Group yields a rutile age of ca. 0.9Ga and documents the occurrence of mafic magmatism coeval with sedimentation in the marginal basin. Detrital zircons from the autochthonous and parautochthonous Andrelândia Group, deposited on the southern margin of the São Francisco Craton, yielded a provenance pattern similar to that of the allochthonous units. This result implies that 1.6-1.2Ga source rocks must be present in the São Francisco Craton. They could be located either in the cratonic area, which is mostly covered by the Neoproterozoic epicontinental deposits of the Bambuí Group, or in the outer paleo-continental margin, buried under the allochthonous units of the Brasília belt. Crustal melting and generation of syntectonic crustal granites and migmatisation at ca. 630Ma mark the orogenic event that started with westward subduction of the São Francisco plate and ended with continental collision against the Paraná block (and Goiás terrane). Continuing collision led to the exhumation and cooling of the Araxá and Passos metamorphic nappes, as indicated by monazite ages of ca. 605Ma and mark the final stages of tectonometamorphic activity in the southern Brasília belt. Whilst continent-continent collision was proceeding on the western margin of the São Francisco Craton along the southern Brasília belt, eastward subduction in the East was generating the 634-599Ma Rio Negro magmatic arc which collided with the eastern São Francisco margin at 595-560Ma, much later than in the Brasília belt. Thus, the tectonic effects of the Ribeira belt reached the southernmost sector of the Brasília belt creating a zone of superposition. The thermal front of this event affected the proximal Andrelândia Group at ca. 588Ma, as indicated by monazite age. The participation of the Amazonian craton in the assembly of western Gondwana occurred at 545-500Ma in the Paraguay belt and ca. 500Ma in the Araguaia belt. This, together with the results presented in this work lead to the conclusion that the collision between the Paraná block and Goiás terrane with the São Francisco Craton along the Brasília belt preceded the accretion of the Amazonian craton by 50-100 million years. © 2003 Elsevier B.V. All rights reserved.

As rochas intrusivas da Formação Serra Geral na Porção leste da Bacia do Paraná no Estado de São Paulo: Aspectos petrográficos e geoquímicos - Resultados preliminares

The purpose of this paper is to present preliminary aspects of the petrography and chemistry of intrusive rocks (sills and dykes) from the eastern portion of the Parana Basin in the State of Säo Paulo. Data from 80 samples of the region show a subaphyric and subophitic nature and have plagioclase (25-50%), augite (3-39%), pigeonite (0-10%) and magnetite (4-20%) as an essential minerals. Apatite and quartz are present as accessory minerals. The geochemical data of intrusive rocks show a basic to intermediate composition (48% < SiO 2 < 56%) and a high Ti nature (TiO 2 > 2%). Based on the minor and trace composition of the intrusive rocks, two different magma types were recognized, named Paranapanema and Pitanga. The spatial distribution of these magma types is not alleatory in the studied region. The intrusive rocks of Pitanga magma type are displayed in the Campinas-Paulinia region, while the Paranapanema magma type cover a large region above that one, between Rio Claro and Cajuru. Furthermore, the chemical composition of the lava flows of the Serra Geral Formation, sampled in this work, reveals a magma of Urubici type. So, the intrusive rocks of the eastern portion of the of State Säo Paulo are not the extension of the lava flows, or they aren't a portions which don't reach the surface.