Emplacement mechanism of the main granite pluton of the Lavras do Sul intrusive complex, South Brazil, determined by magnetic anisotropies

Magnetic fabric and rock magnetism studies were performed on apparently isotropic granite facies from the main intrusion of the Lavras do Sul Intrusive Complex pluton (LSIC, Rio Grande do Sul, South Brazil). This intrusion is roughly circular (similar to 12 x 13.5 km), composed of alkali-calcic and alkaline granitoids, with the latter occupying the margin of the pluton. Magnetic fabrics were determined by applying both anisotropy of low-field magnetic susceptibility (AMS) and anisotropy of anhysteretic remanent magnetization (AARM). The two fabrics are coaxial. The parallelism between AMS and AARM tensors excludes the presence of a single domain (SD) effect on the AMS fabric of the granites. Several rock-magnetism experiments performed in one specimen from each sampled site show that for all sites the magnetic susceptibility is dominantly carried by ferromagnetic minerals, while mainly magnetite carries the magnetic fabrics. Lineations and foliations in the granite facies were successful determined by applying magnetic methods. Magnetic lineations are gently plunging and roughly parallel to the boundaries of the pluton facies, except at the few sites in the central facies which have a radial orientation pattern. In contrast, the magnetic foliations tend to follow the contacts between the different granite facies. They are gently outerward-dipping inside the pluton, and become either steeply southwesterly dipping or vertical towards its margin. The lack of solid-state and subsolidus deformations at outcrop scale and in thin sections precludes deformation after full crystallization of the pluton. This evidence allows us to interpret the observed magnetic fabrics as primary in origin (magmatic) acquired when the rocks were solidified as a result of processes reflecting magma flow. The foliation pattern displays a dome-shaped form for the main LSIC-pluton. However, the alkaline granites which outcrop in the southern part of the studied area have an inward-dipping foliation, and the steeply plunging magnetic lineation suggests that this area could be part of a feeder zone. The magma ascent probably occurred due to ring-diking. (C) 2008 Elsevier B.V. All rights reserved.

Evolution of a rift basin dominated by subaerial deposits: The Guaritas Rift, Early Cambrian, Southern Brazil

Most existing models for the evolution of rift basins predict the development of deep-water depositional systems during the stage of greatest tectonic subsidence, when accommodation generation potentially outpaces sedimentation. Despite this, some rift basins do not present deep-water systems, instead being dominated by subaerial deposits. This paper focuses on one of these particular rift basins, the Cambrian Guaritas Rift, Southern Brazil, characterized by more than 1500 m of alluvial and aeolian strata deposited in a 50-km-wide basin. The deposits of the Guaritas Rift can be ascribed to four depositional systems: basin-border alluvial fans, bedload-dominated ephemeral rivers, mixed-load ephemeral rivers and aeolian dune fields. These four systems are in part coeval and in part succeed each other, forming three stages of basin evolution: (i) Rift Initiation to Early Rift Climax stage, (ii) Mid to Late Rift Climax stage, and (iii) Early Post-Rift stage. The first stage comprises most of the Guaritas Group and is characterized by homogeneous bed-load-dominated river deposits, which do not clearly record the evolution of subsidence rates. The onset of sedimentation of finer-grained deposits occurred as a consequence of a reactivation event that changed the outline of the basin and the distribution of the nearby highlands. This strongly suggests that the capture of the main river system to another depression decreased the sediment supply to the basin. The study of the Guaritas Rift indicates that rift basins in which the sediment supply exceeds the accommodation generation occur as a consequence of moderate subsidence combined with the capture of a major river system to the basin during the initial stages of basin evolution. In these basins, changes in the average discharge of the river system or tectonic modification of the drainage network may be the major control on the stratigraphic architecture. (c) 2009 Published by Elsevier B.V.

Lycopodiopsis derbyi Renault from the Corumbatai Formation in the state of Sao Paulo (Guadalupian of Parana Basin, Southern Brazil): New data from compressed silicified stems

Lycopodiopsis derbyi Renault was analyzed on the basis of compressed silicified stems from four Guadalupian outcrops of the Parana Basin (Corumbatai Formation) in the State of Sao Paulo, Southern Brazil. Dichotomous stems have been recorded, and three different branch regions related to apoxogenesis are described. The most proximal region has larger, clearly rhomboidal leaf cushions, with protruding upper edges; the intermediate transitional region also has rhombic leaf cushions, but they are smaller and less elongated than the lower in the same axis; finally, the most distal region reveals only incipient cushions, with inconspicuous infrafoliar bladders; interspersed microphylls were still attached. A well preserved branch representative of this most distal region was sectioned; it has a siphonostelic cylinder similar to that previously described for L derbyi. The cortex, however, shows new traits, such as a short portion of elongated cells between the periderm and the external cortex (or leaf cushion tissue). The stems were apparently silicified prior to their final burial but were probably not transported for long distances. Their final burial may have taken place during storm events, which were common during the deposition of the Corumbatai Formation. These stems are commonly deformed due to compression, mainly because the internal cortical portions rapidly decayed prior to silicification due to their thin-walled tissue, and are therefore not preserved. The common alkalinity of a shallow marine environment such as that in which the Corumbatai Formation was deposited, should mobilize the silica and favors petrifaction. Based on the new data, an emended diagnosis is proposed and a modification of the identification key published by Thomas and Meyen in 1984 for Upper Paleozoic Lycopsida is suggested. (C) 2009 Elsevier B.V. All rights reserved.

Demographic characteristics and prevalence of serologic markers among blood donors who use confidential unit exclusion (CUE) in Sao Paulo, Brazil: implications for modification of CUE polices in Brazil

BACKGROUND: This study evaluated demographic profiles and prevalence of serologic markers among donors who used confidential unit exclusion (CUE) to assess the effectiveness of CUE and guide public policies regarding the use of CUE for enhancing safety versus jeopardizing the blood supply by dropping CUE. STUDY DESIGN AND METHODS: We conducted a cross-sectional analysis of whole blood donations at a large public blood center in Sao Paulo from July 2007 through June 2009, compared demographic data, and confirmed serologic results among donors who used and who have never used CUE (CUE never). RESULTS: There were 265,550 whole blood units collected from 181,418 donors from July 2007 through June 2009. A total of 9658 (3.6%) units were discarded, 2973 (1.1%) because CUE was used at the current donation (CUE now) and 6685 (2.5%) because CUE was used in the past (CUE past). The CUE rate was highest among donors with less than 8 years of education (odds ratio [OR], 2.78; 95% confidence interval [CI], 2.51-3.08). CUE now donations were associated with higher positive infectious disease marker rates than CUE never donations (OR, 1.41; CI, 1.13-1.77), whereas CUE past donations were not (OR, 1.04; CI, 0.75-1.45). CONCLUSION: The CUE process results in a high rate of unit discard. CUE use on an individual donation appears predictive of a high-risk marker-positive donation and, thus, appears to contribute modestly to blood safety. The policy of discarding units from donors who have previously CUE-positive donations does not improve safety and should be discontinued.

Simple components of the center of FG/J(FG)

Let G be a finite group, F a field, FG the group ring of G over F, and J(FG) the Jacobson radical of FG. Using a result of Berman and Witt, we give a method to determine the structure of the center of FG/J(FG), provided that F satisfies a field theoretical condition.

Sodium Tungstate on Some Biochemical Parameters of the Parotid Salivary Gland of Streptozotocin-Induced Diabetic Rats: A Short-Term Study

Several studies have shown the antidiabetic properties of sodium tungstate. In this study, we evaluated some biochemical parameters of the parotid salivary gland of streptozotocin-induced diabetic rats treated with sodium tungstate solution (2 mg/ml). The studied groups were: untreated control (UC), treated control (TC), untreated diabetic (UD), and treated diabetic (TD). After 2 and 6 weeks of treatment, parotid gland was removed and total protein and sialic acid (free and total) concentration and amylase and peroxidase activities were determined. Data were compared by variance analysis and Tukey test (p < 0.05). The sodium tungstate treatment modestly decreased the glycemia of streptozotocin-induced diabetic rats. At week 2 of the study, parotid gland of diabetic rats presented a reduction of total protein concentration (55%) and an increase of amylase (120%) and peroxidase (160%) activities, free (150%) and total (170%) sialic acid concentration. No alteration in the evaluated parameters at week 6 of the study was observed. Sodium tungstate presented no significant effect in parotid gland. Our results suggest that diabetes causes initial modification in biochemical composition of parotid. However, this gland showed a recovery capacity after 6 week of the experimental time. Sodium tungstate has no effect in peripheral tissues, such as salivary glands.

Cytological Characterization of YpsB, a Novel Component of the Bacillus subtilis Divisome

Cell division in bacteria is carried out by an elaborate molecular machine composed of more than a dozen proteins and known as the divisome. Here we describe the characterization of a new divisome protein in Bacillus subtilis called YpsB. Sequence comparisons and phylogentic analysis demonstrated that YpsB is a paralog of the division site selection protein DivIVA. YpsB is present in several gram-positive bacteria and likely originated from the duplication of a DivIVA-like gene in the last common ancestor of bacteria of the orders Bacillales and Lactobacillales. We used green fluorescent protein microscopy to determine that YpsB localizes to the divisome. Similarly to that for DivIVA, the recruitment of YpsB to the divisome requires late division proteins and occurs significantly after Z-ring formation. In contrast to DivIVA, however, YpsB is not retained at the newly formed cell poles after septation. Deletion analysis suggests that the N terminus of YpsB is required to target the protein to the divisome. The high similarity between the N termini of YpsB and DivIVA suggests that the same region is involved in the targeting of DivIVA. YpsB is not essential for septum formation and does not appear to play a role in septum positioning. However, a ypsB deletion has a synthetic effect when combined with a mutation in the cell division gene ftsA. Thus, we conclude that YpsB is a novel B. subtilis cell division protein whose function has diverged from that of its paralog DivIVA.

Ether-Bond-Containing Ionic Liquids and the Relevance of the Ether Bond Position to Transport Properties

The ionic liquids (ILs) 1-ethoxyethyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, [EtO-(CH(2))(2)MMI][Tf(2)N], and N-(ethoxyethyl)-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, [EtO(CH(2))(2)MMor][Tf(2)N] were synthesized, and relevant properties, such as thermal stability, density, viscosity, electrochemical behavior, ionic conductivity, and self-diffusion coefficients for both ionic species, were measured and compared with those of their alkyl counterparts, 1-n-butyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide, [BMMI][Tf(2)N], and N-n-butyl-N-methylpiperidinium bis(trifluoromethanesulfonyl)imide,[BMP][Tf(2)N] and N-n-butyl-N-methylmorpholinium bis(trilfuoromethanesulfonyl)imide [BMMor][Tf(2)N][. This comparison was done to evaluate the effects caused by the presence of the ether bond in either the side chain or in the organic cation ring. The salt, LiTf(2)N, was added to the systems to estimate IL behavior with regard to lithium cation transport. Pure [EtO(CH(2))(2)MMI][Tf(2)N] and their LiTf(2)N solutions showed low viscosity and the highest conductivity among the ILs studied. The H(R) (AC conductivity/NMR calculated conductivity ratio) values showed that, after addition of LiTf(2)N, ILs containing the ether bond seemed to have a greater number of charged species. Structural reasons could explain these high observed HR values for [EtO(CH(2))(2)MMor][Tf(2)N].

Detailed analysis of the charge transfer complex N,N-dimethylaniline-SO(2) by Raman spectroscopy and density functional theory calculations

Although the amine sulfur dioxide chemistry was well characterized in the past both experimentally and theoretically, no systematic Raman spectroscopic study describes the interaction between N,N-dimethylaniline (DMA) and sulfur dioxide (SO(2)). The formation of a deep red oil by the reaction of SO(2) with DMA is an evidence of the charge transfer (CT) nature of the DMA-SO(2) interaction. The DMA -SO(2) normal Raman spectrum shows the appearance of two intense bands at 1110 and 1151 cm(-1), which are enhanced when resonance is approached. These bands are assigned to nu(s)(SO(2)) and nu(phi-N) vibrational modes, respectively, confirming the interaction between SO(2) and the amine via the nitrogen atom. The dimethyl group steric effect favors the interaction of SO(2) with the ring pi electrons, which gives rise to a pi-pi* low-energy CT electronic transition, as confirmed by time-dependent density functional theory (TDDFT) calculations. In addition, the calculated Raman DMA-SO(2) spectrum at the B3LYP/6-311++g(3df,3pd) level shows good agreement with the experimental results (vibrational wavenumbers and relative intensities), allowing a complete assignment of the vibrational modes. A better understanding of the intermolecular interactions in this model system can be extremely useful in designing new materials to absorb, detect, or even quantify SO(2). Copyright (C) 2009 John Wiley & Sons, Ltd.

Chemical modification of a nanocrystalline TiO(2) film for efficient electric connection of glucose oxidase

A novel biosensor for glucose was prepared by adsorption of 1,1`-bis(4-carboxybenzyl)-4,4`-bipyridinium di-bromide compound (H(2)BpybcBr(2)) onto the surface of a nanocrystalline TiO(2) film deposited onto FTO glasses, which was used as a platform to assemble the enzyme glucose oxidase to the electrode surface. The H(2)BpybcBr(2)/TiO(2)/FTO modified electrode was characterized by scanning electron microscopy, X-ray fluorescence image, cyclic voltammograms and spectroelectrochemical measurements. The immobilization of GOD on functionalized TiO(2) film led to stable amperometric biosensing for glucose with a linear range from 153 mu mol L(-1) to 1.30 mmol L(-1) and a detection limit of 51 mu mol L(-1). The apparent Michaelis-Menten constant (K(m)) was estimated to be 3.76 mmol L(-1), which suggested a high enzyme-substrate affinity. The maximum electrode sensitivity was 1.25 mu A mmol L(-1). The study proved that the combination of viologen mediators with TiO(2) film retains the electrocatalytic activity of the enzyme, and also enhances the electron transfer process, and hence regenerating the enzyme in the reaction with glucose. (C) 2010 Elsevier Inc. All rights reserved.

Single-wall carbon nanotubes modified with organic dyes: Synthesis, characterization and potential cytotoxic effects

This work deals with the covalent functionalization of single-wall carbon nanotubes (SWNTs) with phenosafranine (PS) and Nile Blue (NB) dyes. These dyes can act as photosensitizers in energy and electron transfer reactions, with a potential to be applied in photodynamic therapy. Several changes in the characteristic Raman vibrational features of the dyes suggest that a covalent modification of the nanotubes with the organic dyes occurs. Specifically, the vibrational modes assigned to the NH(2) moieties of the dyes are seen to disappear in the SWNT-dye nanocomposites, corroborating the bond formation between amine groups in the dyes and carboxyl groups in the oxidized nanotubes. The X-ray absorption (XANES) data also show, that the intense band at 398.6 eV attributed to 1s -> 2p pi* transition of the nitrogen of the aromatic PS ring, is shifted due to the bonding with the carbonic structure of the SWNTs. The cytotoxicity data of dyes-modified SWNT composites in the presence and absence of light shows that the SWNT-NB (4 mu g/mL) composite presents a good photodynamic effect, namely a low toxicity in the dark, higher toxicity in the presence of light and also a reduced dye photobleaching by auto-oxidation. (C) 2010 Elsevier B.V. All rights reserved.

Direct Kinetic Observation of the Chemiexcitation Step in Peroxyoxalate Chemiluminescence

A high-energy intermediate in the peroxyoxalate reaction can be accumulated at room temperature under specific reaction conditions and in the absence of any reducing agent in up to micromolar concentrations. Bimolecular interaction of this intermediate, accumulated in the reaction of oxalyl chloride with hydrogen peroxide, with an activator (highly fluorescent aromatic hydrocarbons with low oxidation potential) added in delay shows unequivocally that this intermediate is responsible for chemiexcitation of the activator. Activation parameters for the unimolccular decomposition of this intermediate (Delta H(double dagger) = 11.2 kcal mol(-1); Delta S(double dagger) = -23.2 cal mol(-1) K(-1)) and for its bimolecular reaction with 9,10-diphenylanthracene (Delta H(double dagger) = 4.2 kcal mol(-1); Delta S(double dagger) = -26.9 cal mol(-1) K(-1)) show that this intermediate is much less stable than typical 1,2-dioxetanes and 1,2-dioxetanones and demonstrate its highly favored interaction with the activator. Therefore, it can be inferred that structural characterization of the high-energy intermediate in the presence of an activator must be highly improbable. The observed linear free-energy correlation between the catalytic rate constants and the oxidation potentials of several activators definitely confirms the occurrence of the chemically initiated electron-exchange luminescence (CIEEL) mechanism in the chemiexcitation step of the peroxyoxalate system.

A preliminary characterization of the mutagenicity of atmospheric particulate matter collected during sugar cane harvesting using the Salmonella/microsome microsuspension assay

During sugar cane harvesting season, which occurs from May to November of each year, the crops are burnt, cut, and transported to the mills. There are reports showing that mutagenic activity and PAH content increase during harvesting season in some areas of Sao Paulo State in comparison with nonharvesting periods. The objective of this work was to preliminarily characterize the mutagenic activity of the total organic extracts as well as corresponding organic fractions of airborne particulate matter (PM) collected twice from two cities, Araraquara (ARQ) and Piracicaba (PRB), during sugar cane harvesting season using the Salmonella/microsome microssuspension assay. One sample collected in Sao Paulo metropolitan area was also included. The mutagenicity of the total extracts ranged from 55 to 320 revertants per cubic meter without the addition of S9 and from not detected to 57 revertants per cubic meter in the presence of S9 in areas with sugar cane plantations. Of the three fractions analyzed, the most polar ones (nitro and oxy) were the most potent. A comparison of the response of TA98 with YG1041 and the increased potencies without S9 indicated that nitro compounds are causing the observed effect. More studies are necessary to verify the sources of the mutagenic activity such as burning of vegetal biomass and combustion of heavy duty vehicles used to transport the sugar cane to the mills. The Salmonella/microsome assay can be an important tool to monitor the atmosphere for mutagenicity during sugar cane harvesting season.

Bichromophoric behavior of nitrophenyl-triazene anions: a resonance Raman spectroscopy investigation

Highly delocalized molecular frameworks with intense charge transfer transitions, known as push-pull systems, are of central interest in many areas of chemistry, as is the case of nitrophenyl-triazene derivatives. The 1,3-bis(2-nitrophenyl)triazene and 1,3-bis(4-nitrophenyl)triazene were investigated by electronic (UV-Vis) and resonance Raman (RR) spectroscopies. The bichromophoric behavior of 1,3-bis(4-nitrophenyl)triazene anion opens the possibility of tuning with visible radiation, two distinct electronic states. The RR profiles of nitrophenyl-triazene derivatives clearly show that the first allowed electronic state can be assigned to a charge transfer from the ring pi system to the NO2 moiety (ca 520 nm), while the second, as a charge transfer from N-3(-) to the aromatic ring (ca 390 nm). In the para-substituted derivative, a more efficient electron transfer and a greater energy separation between the two excited states are observed. Copyright (C) 2008 John Wiley & Sons, Ltd.

Understanding the Effect of Adsorption Geometry over Substrate Selectivity in the Surface-Enhanced Raman Scattering Spectra of Simazine and Atrazine

This paper studies the selectivity of Well-defined Au and Ag nanostructures as substrates for the SERS, (surface-enhanced Raman scattering) detection of simazine (6-chloro-N,N`-diethyl-1,3,5-triazine-2,4-diamine) and atrazine (6-chloro-N-ethyl-N`-isopropyl-1,3,5-triazine-2,4-diamine). Our data showed that simazine and atrazine displayed similar SERS spectra when the Au was employed as substrate. Conversely, distinct SERS signatures were obtained upon the utilization of Ag substrates. Density functional theory (DFT) calculations and vibrational assignments suggested that, while simazine and atrazine adsorbed on Au via the N3 position of the triazine ring, simazine adsorbed on Ag via N3 and atrazine via N5. The results presented herein demonstrated that the adsorption geometry of analyte molecules can play a central role over substrate selectivity in SERS, which is particularly important in applications involving ultrasensitive analysis of mixtures containing structurally similar molecules.