Chemistry of Biotites and Whole Rocks from the Rapakivi Itu Complex (Late Precambrian), State of São Paulo, SE Brazil

Chemical analyses for biotites and their host rocks from the Cabreúva (three facies) and Salto (five facies) intrusions from the multiple-centered rapakivi Itu Complex, State of São Paulo, Brazil, are presented and compared. The Cabreúva intrusion comprises different kinds of mainly even-grained biotite and hornblende-bearing syenogranites, monzogranites and quartz syenites and the Salto intrusion several types of mainly porphyritic biotite syenogranites, some of them hornblende-bearing. The biotites from the Salto intrusion (S-micas) show a more restricted composition than those from the Cabreúva intrusion (C-micas). This reflects the chemical variability of the two bodies which is smaller in the Salto intrusion and larger in the Cabreúva pluton. In the AlIV x Fet/(Fet+Mg) diagram the S- and C-micas show similar AlIV contents, around 2.2-2.3, but C-micas have higher Fet/(Fet+Mg) ratios (0.7-0.9) compared to those of S-micas (0.5-0.6). In the Mg:(Al+Fe+3+Ti):(Fe+2+Mn) diagram the S-micas are defined as Fe+2-biotites and the C-micas occupy the area between the Fe+2-biotites and the siderophyllite/lepidomelane fields, slightly overlapping the latter. In the Al2O3 × FeOt, MgO × FeOt, Al2O3 x MgO and Alt x Mg diagrams, the S-micas always lie on the calc-alkaline/alkaline boundary (or in the subalkaline field) whereas the C-micas systematically plot in the alkaline field, reflecting the higher alkalis content of the Cabreúva intrusion. In the Fet/(Fet+Mg) x SiO2 diagram, the S-micas lie on a smooth line whereas the C-micas from the different facies are separated by distinct chemical gaps reflecting the major or minor chemical overlapping of the facies from the Salto and Cabreúva intrusions.

Alteration of soil properties through a weathering sequence as evaluated by spectral reflectance

In the study of physical, chemical, and mineralogical data related to the weathering of soils and the quantification of their properties, remote sensing constitutes an important technique that, in addition to conventional analyses, can contribute to soil survey. The objectives of this research were to characterize and differentiate soils developed from basaltic rocks that occur in the Parana state, Brazil and to quantify soil properties based on their spectral reflectance. These observations were used to verify the relationship between the soils and reflectance with regard to weathering, organic matter (OM), and forms of Fe. From the least to the most weathered soil, we used a Typic Argiudoll (Reddish Brunizem), Rhodudalf (Terra Roxa Estruturada), and Rhodic Hapludox (Very Dark Red Latosol). The spectral reflectances between 400 and 2500 nm were obtained in the laboratory from soil samples collected at two depth increments, 0- to 20- and 40- to 60-cm, using an Infra Red Intelligent Spectroradiometer (IRIS). Correlation, regression, and discriminant estimates were used in analyzing the soil and spectral data. Results of this study indicated that soils could be separated at the soil-type level based on reflectance intensity in various absorption bands. Soil collected in the 40- to 60-cm depth appeared to have higher reflectance intensities than those from the 0- to 20-cm depth. Removal of OM from soil samples promoted higher reflectance intensity in the entire spectrum. Amorphous and crystalline Fe influenced reflectance differently. Weathering of basaltic soils was correlated with alterations in the reflectance intensities and absorption features of the spectral curves. Multivariate analysis demonstrated that this technique was efficient in the estimation of clay, silt, kaolinite, crystalline Fe, amorphous Fe, and Mg through the use of reflected energy of the soils.

Dispersed lipid liquid crystalline phases stabilized by a hydrophobically modified cellulose

Aqueous dispersions of monoolein (MO) with a commercial hydrophobically modified ethyl hydroxyethyl cellulose ether (HMEHEC) have been investigated with respect to the morphologies of the liquid crystalline nanoparticles. Only very low proportions of HMEHEC are accepted in the cubic and lamellar phases of the monoolein-water system. Due to the broad variation of composition and size of the commercial polymer, no other single-phase regions were found in the quasi-ternary system. Interactions of MO with different fractions of the HMEHEC sample induced the formation of lamellar and reversed hexagonal phases, identified from SAXD, polarization microscopy, and cryogenic TEM examinations. In excess water (more than 90 wt %) coarse dispersions are formed more or less spontaneously, containing particles of cubic phase from a size visible by the naked eye to small particles observed by cryoTEM. At high polymer/MO ratios, vesicles were frequently observed, often oligo-lamellar with inter-lamellar connections. After homogenization of the coarse dispersions in a microfluidizer, the large particles disappeared, apparently replaced by smaller cubic particles, often with vesicular attachments on the surfaces, and by vesicles or vesicular particles with a disordered interior. At the largest polymer contents no proper cubic particles were found directly after homogenization but mainly single-walled defected vesicles with a peculiar edgy appearance. During storage for 2 weeks, the dispersed particles changed toward more well-shaped cubic particles, even in dispersions with the highest polymer contents. In some of the samples with low polymer/MO ratio, dispersed particles of the reversed hexagonal type were found. A few of the homogenized samples were freeze-dried and rehydrated. Particles of essentially the same types, but with a less well-developed cubic character, were found after this treatment. © 2007 American Chemical Society.

A tectônica meso-cenozóica de parte da borda nordeste da Bacia do Paraná: traços de fissão em apatita

The possible development of thermal events in the central portion of São Paulo state was described based on apatite fission track analysis. Using apatites of sedimentary rocks of the Paraná Basin, modeling the thermal history was made possible due to the homogeneity of the data. Every thermal history begins with a total annealing of fission tracks, related to the Serra Geral magmatism, evolving into a cooling period. In addition to cooling after the magmatism (Early Cretaceous) two other periods of cooling were also detected, registered in the Late Cretaceous/ Paleocene and Eocene, driven as much by uplift with tectonic denudation as by faulting. The nearest portion of the edge of the basin (external to the Dome of Pitanga), registered a period of warming over the Paleocene that can be attributed to the increase in the geothermal gradient. The periods of cooling have a regional and temporal relationship with the tectonic events that occurred in the southeastern Brazil and were described in the crystalline basement. The period of warming, registered in the Late Cretaceous/ Paleocene, has local occurrence and can be found only in the southern portion of the studied area.

Microstructure, crystalline phase, and dielectric property analyses of TiO2 composition with ZrO2 addition

For microwave applications, including mobile and satellite communications, ceramic resonators should have a high dielectric constant, low dielectric losses, and high frequency stability. In this sense, TiO2-ZrO 2 ceramics have been investigated as a function of sintering behavior, phase composition, and microstructure. The ceramics were densified reaching a value of about 86% of theoretical density at 1400°C sintering temperature. The ceramics are prepared by mixing raw materials with the following TiO2-ZrO2 weight % ratio: 100 to 0, 90 to 10, and 80 to 20, respectively. The measured dielectric constants are between 79 and 88 values, while the quality factor due to dielectric losses are between 2820 and 5170. These results point out the influence of Ti/Zr ratio on controlling the dielectric properties. © (2010) Trans Tech Publications.

Subluxation of the crystalline lens: A no-ring approach

Purpose: To report the surgical technique and outcomes of a no-ring approach to posterior chamber intraocular lens (IOL) implantation in children and young adults with subluxation of the crystalline lens. Methods: A three-piece 5.5-mm hydrophobic acrylic IOL was implanted in which the optic and one haptic were inside the capsular bag and the other haptic was in the ciliary sulcus. The implantations were done in 13 eyes of 10 patients with lens subluxation. One haptic was fixated in the ciliary sulcus by passing it through an operculum-shaped opening in the capsular bag edge, made between 2 and 3 clock hours, clockwise from the middle point of the subluxated area. Results: The mean age of the 10 patients was 12.61 ± 8.04 years and the mean follow-up was 21.38 ± 11.29 months. The mean preoperative and postoperative best-corrected visual acuity (BCVA) was 1.15 ± 0.58 and 0.37 ± 0.17 logarithm of the minimum angle of resolution, respectively, in 11 measured eyes. The postoperative BCVA was 20/40 or better in 4 eyes (36.36%), between 20/40 and 20/60 in 6 eyes (54.54%), and between 20/80 and 20/100 in 1 eye (9.09%). The BCVA improved in all eyes. Postoperative IOL decentration between 1.0 and 1.5 mm occurred in 3 of 13 eyes (23.08%). Conclusion: The results indicate that the no-ring technique allows centration of an IOL implanted into a subluxated capsular bag without using capsule tension rings. © SLACK Incorporated.

Fractal dimension and Shannon's entropy analyses of the architectural complexity caused by the inflammatory reactions induced by highly crystalline polyvinyl alcohol) microspheres implanted in subcutaneous tissues of the Wistar rats

The results of the histopathological analyses after the implantation of highly crystalline PVA microspheres in subcutaneous tissues of Wistar rats are here in reported. Three different groups of PVA microparticles were systematically studied: highly crystalline, amorphous, and commercial ones. In addition to these experiments, complementary analyses of architectural complexity were performed using fractal dimension (FD), and Shannon's entropy (SE) concepts. The highly crystalline microspheres induced inflammatory reactions similar to the ones observed for the commercial ones, while the inflammatory reactions caused by the amorphous ones were less intense. Statistical analyses of the subcutaneous tissues of Wistar rats implanted with the highly crystalline microspheres resulted in FD and SE values significantly higher than the statistical parameters observed for the amorphous ones. The FD and SE parameters obtained for the subcutaneous tissues of Wistar rats implanted with crystalline and commercial microparticles were statistically similar. Briefly, the results indicated that the new highly crystalline microspheres had biocompatible behavior comparable to the commercial ones. In addition, statistical tools such as FD and SE analyses when combined with histopathological analyses can be useful tools to investigate the architectural complexity tissues caused by complex inflammatory reactions. © 2012 WILEY PERIODICALS, INC.

Influence of mineralizer agents on the growth of crystalline CeO 2 nanospheres by the microwave-hydrothermal method

Cystalline ceria (CeO2) nanoparticles have been synthesized by a simple and fast microwave-assisted hydrothermal (MAH) under NaOH, KOH, and NH4OH mineralizers added to a cerium ammonium nitrate aqueous solution. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transformed-IR and Raman spectroscopies. Rietveld refinement reveals a cubic structure with a space group Fm3m while infrared data showed few traces of nitrates. Field emission scanning microcopy (FEG-SEM) revealed a homogeneous size distribution of nanometric CeO2 nanoparticles. The MAH process in KOH and NaOH showed most effective to dehydrate the adsorbed water and decrease the hydrogen bonding effect leaving a weakly agglomerated powder of hydrated ceria. TEM micrographs of CeO2 synthesized under MAH conditions reveal particles well-dispersed and homogeneously distributed. The MAH enabled cerium oxide to be synthesized at 100 °C for 8 min. © 2012 Elsevier B.V. All rights reserved.

Use of conventional electrochemical techniques to produce crystalline FeRh alloys induced by Ag seed layer

By combining galvanic displacement and electrodeposition techniques, an ordered Fe20Rh80 structure deposited onto brass was investigated by X-ray diffractometry, Mössbauer spectroscopy and magnetization measurements. Mössbauer and X-ray diffraction analyses suggest that the Fe-Rh alloy directly electrodeposited onto brass displays a nanocrystalline state while a similar alloy deposited onto Ag/brass shows a faced centered cubic-like structure, with dendrites-like features. These results directly indicate that the presence of Ag seed layer is responsible for the Fe-Rh alloy crystallization process. In addition, room temperature Mössbauer data indicate firstly paramagnetic states for two Fe-species. In the dominant Fe-species (major fraction of the Mössbauer spectra), Fe atoms are situated at a cubic environment and it can be attributed to the γ-Fe20Rh80 alloy based on their hyperfine parameters. In the second species, Fe atoms are placed in a non-local symmetry, which can be related to Fe atoms at the grain boundaries or/and Fe small clusters. These Fe-clusters are in superparamagnetic state at room temperature, but they may be ordered below 45 K, as suggested by magnetization data. © 2013 Elsevier B.V. All rights reserved.

Crystalline rock outcrops in the Atlantic Forest of northeastern Brazil: Vascular flora, biological spectrum, and invasive species

We studied the vegetation of two crystalline rock outcrops in the Atlantic Forest of northeastern Brazil. We recorded typically rupicolous species, which are rare or classified as extremely endangered, such as Aechmea guainumbiorum, found exclusively in one of the study sites. In both areas there was a predominance of therophytes over other life-forms, in contrast to observations made in rock outcrops of the southern Atlantic Forest. Therophytes also stood out in other rock outcrops at similar latitudes as our study site, regardless of the surrounding vegetation. Plants of other life-forms had significantly lower richness and showed adaptations to drought, such as succulent stem, pseudobulbs, dense pilosity, and underground storage organs. Our results suggest that invasive species may modify the vegetation of crystalline rock outcrops, as they change the number of species of all life-forms in comparison between sites. Hence, our results present the biological identity of these rupicolous habitats, which are marginal to forests, and point to the need for conserving them, in order to protect the Atlantic Forest's biodiversity. © 2013 Botanical Society of Sao Paulo.

Influence of current density on crystalline structure and magnetic properties of electrodeposited Co-rich CoNiW alloys

The influence of current density, at the interval 5-100 mA cm-2, on the structural and magnetic properties of electrodeposited (Co 100-xNix)100-yWy alloys (x = 23-33.5 at. % Ni, y = 1.7-7.3 at. % W) was studied from a glycine-containing bath. W-content decreases with the increase of the current density magnitude. X-ray data have shown stabilization of hexagonal close packed, face centered cubic or a mixture of these structures by modulating the applied cathodic current density, for values lower than 50 mA cm-2. Two structural phase transitions were observed: one from hexagonal close packed to face centered cubic structural transition occurring for a current density of 20 mA cm -2, and another one, from cubic crystalline phase to amorphous state, which happens for values higher than 50 mA cm-2. These structural phase transitions seem to be associated with the W-content as well as average crystalline grain sizes that reduce with increasing the current density value. The grain size effect may explain the face centered cubic stabilization in Co-rich CoNiW alloys, which was initially assumed to be basically due to H-adsorption/incorporation. Magnetic properties of Co-rich CoNiW alloys are strongly modified by the current density value; as a result of the changes on the W-content and their structural properties© 2013 Elsevier B.V. All rights reserved.

Geochemical and radioactivity characterization of rocks from the Rio Preto (Go) Project

The Rio Preto Project, developed by the extinct Brazilian nuclear state company, Nuclebrás, during the late 70s and early 80s, consisted of basic geological mapping and radiometric characterization by aerogeophysical gamma-ray spectrometry, without channel discrimination, of a surface area of 650 km2 located to the west of the Chapada dos Veadeiros National Park on the northeastern of Goiás State, Brazil, including the confluence area of Claro and Preto Rivers. Additionally, the natural radioelements U, Th and 40K were determined by gamma-ray spectrometry in 300 rock samples from cores of the Rio Preto Project area. The tests were conducted at LABIDRO-Isotopes and Hydrochemistry Laboratory of the Departament of Petrology and Metallogeny (DPM) of the Institute of Geosciences and Exact Sciences, UNESP, in Rio Claro, SP, Brazil. This paper reports the results of petrographic characterization and chemical analyses of major oxides (SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO and P2O5) for all samples used to determine the natural radioelements present in the region. The organic matter content results obtained by colorimetry are also reported for selected cores of different lithotypes in order to investigate the possible relationship between graphite and the radioelements uranium and thorium. Finally, uranium content and 234U/238U activity ratio data for selected samples of schists and gneisses of the Lower Member of the Ticunzal Formation suggest the influence of weathering processes in the area. © 2012 Sociedade Brasileira de Geofísica.

Evidence for euphotic zone anoxia during the deposition of Aptian source rocks based on aryl isoprenoids in petroleum, Sergipe-Alagoas Basin, northeastern Brazil

Four crude oil samples from the Sergipe-Alagoas Basin, northeastern Brazil, were analyzed using full scan gas chromatography-quadrupole mass spectrometry (GC-qMS) for biomarkers, in order to correlate them using aromatic carotenoids thereby enhancing knowledge about the depositional environment of their source rocks. The geochemical parameters derived from saturated fractions of the oils show evidence of little or no biodegradation and similar thermal maturation (Ts/(Ts+Tm) for terpanes, C29 αββ/(αββ+ααα), C27, and C29 20S/(20S+20R) for steranes). Low pristane/phytane ratios and the abundance of gammacerane and β-carotane are indicative of an anoxic and saline depositional environment for the source rocks. Moreover, we identified a large range of diagenetic and catagenetic products of the aromatic carotenoid isorenieratene, including C40, C33, and C32 diaryl isoprenoids and aryl isoprenoid derivatives with short side chains and/or additional rings. These results indicate anoxia in the photic zone during the deposition of the source rocks. © 2013 The Authors.

Enzymatic transesterification of soybean oil with ethanol using lipases immobilized on highly crystalline PVA microspheres

Polyvinyl alcohol (PVA) microspheres with different degree of crystallinity were used as solid supports for Rhizomucor miehei lipase immobilization, and the enzyme-PVA complexes were used as biocatalysts for the transesterification of soybean oil to fatty acid ethyl esters (FAEE). The amounts of immobilized enzyme on the polymeric supports were similar for both the amorphous microspheres (PVA4) and the high crystalline microspheres (PVA25). However, the enzymatic activity of the immobilized enzymes was depended on the crystallinity degree of the PVA microspheres: enzymes immobilized on the PVA4 microspheres have shown low enzymatic activity (6.13 U mg-1), in comparison with enzymes immobilized on the high crystalline PVA25 microspheres (149.15 U mg-1). A synergistic effect was observed for the enzyme-PVA25 complex during the transesterification reaction of soybean oil to FAEE: transesterification reactions with free enzyme with the equivalent amount of enzyme that were immobilized onto the PVA25 microspheres (5.4 U) have yielded only 20% of FAEE, reactions with the pure highly crystalline microsphere PVA25 have not yielded FAEE, however reactions with the enzyme-PVA25 complexes have yielded 66.3% of FAEE. This synergistic effect of an immobilized enzyme on a polymeric support has not been observed before for transesterification reaction of triacylglycerides into FAEE. Based on ATR-FTIR, 23Na- and 13C-NMR-MAS spectroscopic data and the interaction of the polymeric network intermolecular hydrogen bonds with the lipases residual amino acids a possible explanation for this synergistic effect is provided. © 2013 Elsevier Ltd. All rights reserved.

Microwave-hydrothermal synthesis of single-crystalline Co3O 4 spinel nanocubes

An efficient microwave-hydrothermal (MAH) method has been developed for the synthesis of highly crystalline Co3O4 spinel nanocubes via β-Co(OH)2 without any surfactant assistance. The structure and surface chemical composition along the growth process are studied. The effects as well as the merits of the MAH method on the processing and characteristics of obtained Co3O4 spinel nanocubes are highlighted. © 2013 The Royal Society of Chemistry.