Structural role of fluoride in the ion-conducting glass system B(2)O(3)-PbO-LiF studied by single- and double-resonance NMR

The local structure of an ion-conducting glass with nominal composition 50B(2)O(3)-10PbO-40LiF has been investigated by complementary (7)Li, (11)B, (19)F, and (207)Pb single- and double-resonance experiments. The results give insight into the structural role of the lithium fluoride additive in borate glasses: (1) LiF is seen to actively participate in the network transformation process contributing to the conversion of three- into four-coordinate boron units, as shown by (11)B single-resonance as well as by (11)B{(19)F} and (19)F{(11)B} double-resonance experiments. (2) (19)F signal quantification experiments suggest substantial fluoride loss, presumably caused by formation of volatile BF(3). A part of the fluoride remains in the dopant role, possibly in the form of small LiF-like cluster domains, which serve as a mobile ion supply. (3) The extent of lithium-fluorine and lead-fluorine interactions has been characterized by (7)Li{(19)F} and (207)Pb{(19)F} REDOR and SEDOR experiments. On the basis of these results, a quantitative structural description of this system has been developed.

Evidence for magnetic phase separation in La(0.86)Sr(0.14)Mn(1-x)Cu(x)O(3+delta) manganites from NMR and magnetic measurements

Polycrystalline La(0.86)Sr(0.14)Mn(1-x)Cu(x)O(3+delta) (x = 0, 0.05, 0.10, 0.15, 0.20) manganites were investigated by means of magnetic measurements and zero-field (139)La and (55)Mn nuclear magnetic resonance (NMR) spectroscopy. Magnetization versus temperature measurements revealed a paramagnetic to ferromagnetic transition in most samples, with lower Curie temperatures and broader transitions for samples with higher Cu contents. The details of the magnetization measurements suggested a phase-separated scenario, with ferromagnetic clusters embedded in an antiferromagnetic matrix, especially for the samples with large Cu contents (x = 0.15 and 0.20). Zero-field (139)La NMR measurements confirmed this finding, since the spectral features remained almost unchanged for all Cu-doped samples, whereas the bulk magnetization was drastically reduced with increasing Cu content. (55)Mn NMR spectra were again typical of ferromagnetic regions, with a broadening of the resonance line caused by the disorder introduced by the Cu doping. The results indicate a coexistence of different magnetic phases in the manganites studied, with the addition of Cu contributing to the weakening of the double-exchange interaction in most parts of the material.

Non-invasive strategy in assessing asthma through biofluids metabolomics exploration: exhaled breath and urine potentialities

Asthma is a significant health issue in the pediatric population with a noteworthy growth over the years. The proposed challenge for this PhD thesis was the development of advanced methodologies to establish metabolomic patterns in urine and exhaled breath associated with asthma whose applicability was subsequently exploited to evaluate the disease state, the therapy adhesion and effect and for diagnostic purposes. The volatile composition of exhaled breath was studied combining headspace solid phase microextraction (HS-SPME) with gas chromatography coupled to mass spectrometry or with comprehensive two-dimensional gas chromatography coupled to mass spectrometry with a high resolution time of flight analyzer (GC×GC–ToFMS). These methodologies allowed the identification of several hundred compounds from different chemical families. Multivariate analysis (MVA) led to the conclusion that the metabolomic profile of asthma individuals is characterized by higher levels of compounds associated with lipid peroxidation, possibly linked to oxidative stress and inflammation (alkanes and aldehydes) known to play an important role in asthma. For future applications in clinical settings a set of nine compounds was defined and the clinical applicability was proven in monitoring the disease status and in the evaluation of the effect and / or adherence to therapy. The global volatile metabolome of urine was also explored using an HSSPME/GC×GC–ToFMS method and c.a. 200 compounds were identified. A targeted analysis was performed, with 78 compounds related with lipid peroxidation and consequently to oxidative stress levels and inflammation. The urinary non-volatile metabolomic pattern of asthma was established using proton nuclear magnetic resonance (1H NMR). This analysis allowed identifying central metabolic pathways such as oxidative stress, amino acid and lipid metabolism, gut microflora alterations, alterations in the tricarboxylic acid (TCA) cycle, histidine metabolism, lactic acidosis, and modification of free tyrosine residues after eosinophil stimulation. The obtained results allowed exploring and demonstrating the potential of analyzing the metabolomic profile of exhaled air and urine in asthma. Besides the successful development of analysis methodologies, it was possible to explore through exhaled air and urine biochemical pathways affected by asthma, observing complementarity between matrices, as well as, verify the clinical applicability.

Atividades Biológicas De Xilana De Sabugo De Milho

The corn cob is an agricultural by-product still little used, this in part due to the low knowledge of the biotechnological potential of their molecules. Xylan from corn cobs (XSM) is a polysaccharide present in greater quantity in the structure of plant and its biotechnology potential is little known. This study aimed to the extraction, chemical characterization and evaluation of biological activities of xylan from corn cobs. To this end, corncobs were cleaned, cut, dried and crushed, resulting in flour. This was subjected to a methodology that combines the use of alkaline conditions with waves of ultrasound. After methanol precipitation, centrifugation and drying was obtained a yield of 40% (g/g flour). Chemical analysis indicated a high percentage of polysaccharides in the sample (60%) and low contamination by protein (0.4%) and phenolic compounds (> 0.01%). Analysis of monosaccharide composition indicated the presence of xylose:glucose:arabinose:galactose:mannose:glucuronic acid in a molar ratio 50:20:15:10:2.5:2.5. The presence of xylan in the sample was confirmed by nuclear magnetic resonance (¹H and ¹³C) and infrared spectroscopy (IR). Tests were conducted to evaluate the antioxidant potential of XSM. This showed a total antioxidant capacity of 48.45 EAA/g sample. However, did not show scavenging activity of superoxide and hydroxyl radical and also reducing power. But, showing a high capacity chelating iron ions with 70% with about 2 mg/mL. The ability to XSM to influence cell proliferation in culture was also evaluated. This polymer did not influence the proliferation of normal fibroblast cells (3T3), however, decreased the rate of proliferation of tumor cells (HeLa) in a dose-dependent, reaching an inhibition of about 50% with a concentration around 2 mg/mL. Analyzing proteins related to cell death, by immunoblotting, XSM increases the amount of Bax, Bcl-2 decrease, increase cytochrome c and AIF, and reduce pro-caspase-3, indicating the induction of cell death induced apoptosis dependent and independent of caspase. XSM did not show anticoagulant activity in the PT test. However, the test of activated partial thromboplastin time (aPTT), XSM increased clotting time at about 5 times with 600 μg of sample compared with the negative control. The presence of sulfate on the XSM was discarded by agarose gel electrophoresis and IR. After carboxyl-reduction of XSM the anticoagulant activity decreased dramatically. The data of this study demonstrate that XSM has potential as antioxidant, antiproliferative and anticoagulant compound. Future studies to characterize these activities of XSM will help to increase knowledge about this molecule extracted from corn and allow their use in functional foods, pharmaceuticals and chemical industries.

Preparação de resinas de poliuretana à base de óleo de mamona e dietanolamina

The aim of this work was the preparation of polyols from reactions between castor oil and dietanolamine to increase the hydroxyl content and the network degree in the products to application in electronic devices. The polyols and the mixtures obtained were characterized by nuclear magnetic ressonance. Castor oil (CO) is a natural triglyceride - based polyol possessing hydroxyl groups, which allow several reactions that produce many different products. Among them are the polyurethanes (PU), which have been considered an ideal product for the covering of electricelectronic circuits, due to their excellent electrical, shock-absorbing, solvents resistance and hydrolytic stability properties. About 90% of the fatty acids present in the castor oil are ricinoleic acid (12-hydroxyoleic acid), while the remaining 10% correspond to non-hydroxylated fatty acids, mainly linoleic and oleic acids. The chemical analysis of castor oil indicates a hydroxyl number of 2.7. In this work, a polyol was obtained by the reaction of the CO with diethanolamine (DEA), in order to elevate the hydroxyl value from 160 to 230 or to 280 mgKOH/g, and characterized by nuclear magnetic resonance (NMR) 1H and 13C (Mercury 200). The polyadition of the resulting polyol with isophorone diisocianate (IPDI) was carried out at 60°C, and the reaction kinetics was followed by rheological measurements in a Haake RS150 rheometer. The electrical properties were determined in a HP LCR Meter 4262A, at 1.0 Hz and 10.0 KHz. The chemical analysis showed that the polyols obtained presented hydroxyl number from 230 to 280 mgKOH/g. The polyadition reaction with IPDI produced polyurethane resins with the following properties: hardness in the range from 45 shore A to 65 shore D (ASTM D2240); a dielectric constant of 3.0, at 25°C (ASTM D150). Those results indicate that the obtained resins present compatible properties to the similar products of fossil origin, which are used nowadays for covering electric-electronic circuits. Therefore, the PUs from castor oil can be considered as alternative materials of renewable source, free from the highly harmful petroleum - derived solvents

Cardiovascular assessment of patients with Ullrich-Turner's Syndrome on Doppler echocardiography and magnetic resonance imaging

OBJECTIVE: To assess the cardiovascular features of Ullrich-Turner's syndrome using echocardiography and magnetic resonance imaging, and to correlate them with the phenotype and karyotype of the patients. The diagnostic concordance between the 2 methods was also assessed. METHODS: Fifteen patients with the syndrome were assessed by echocardiography and magnetic resonance imaging (cardiac chambers, valves, and aorta). Their ages ranged from 10 to 28 (mean of 16.7) years. The karyotype was analyzed in 11 or 25 metaphases of peripheral blood lymphocytes, or both. RESULTS: The most common phenotypic changes were short stature and spontaneous absence of puberal development (100%); 1 patient had a cardiac murmur. The karyotypes detected were as follows: 45,X (n=7), mosaics (n=5), and deletions (n=3). No echocardiographic changes were observed. In regard to magnetic resonance imaging, coarctation and dilation of the aorta were found in 1 patient, and isolated dilation of the aorta was found in 4 patients. CONCLUSION: The frequencies of coarctation and dilation of the aorta detected on magnetic resonance imaging were similar to those reported in the literature (5.5% to 20%, and 6.3% to 29%, respectively). This confirmed the adjuvant role of magnetic resonance imaging to Doppler echocardiography for diagnosing cardiovascular alterations in patients with Ullrich-Turner's syndrome.

Radiography, computed tomography and magnetic resonance imaging at 0.5 Tesla of mechanically inducedosteoarthritis in rabbit knees

In the present experimental study we assessed induced osteoarthritis data in rabbits, compared three diagnostic methods, i.e., radiography (XR), computed tomography (CT) and magnetic resonance imaging (MRI), and correlated the imaging findings with those obtained by macroscopic evaluation. Ten young female rabbits of the Norfolk breed were used. Seven rabbits had the right knee immobilized in extension for a period of 12 weeks (immobilized group), and three others did not have a limb immobilized and were maintained under the same conditions (control group). Alterations observed by XR, CT and MRI after the period of immobilization were osteophytes, osteochondral lesions, increase and decrease of joint space, all of them present both in the immobilized and non-immobilized contralateral limbs. However, a significantly higher score was obtained for the immobilized limbs (XT: P = 0.016, CT: P = 0.031, MRI: P = 0.0156). All imaging methods were able to detect osteoarthritis changes after the 12 weeks of immobilization. Macroscopic evaluation identified increased thickening of joint capsule, proliferative and connective tissue in the femoropatellar joint, and irregularities of articular cartilage, especially in immobilized knees. The differences among XR, CT and MRI were not statistically significant for the immobilized knees. However, MRI using a 0.5 Tesla scanner was statistically different from CT and XR for the non-immobilized contralateral knees. We conclude that the three methods detected osteoarthritis lesions in rabbit knees, but MRI was less sensitive than XR and CT in detecting lesions compatible with initial osteoarthritis. Since none of the techniques revealed all the lesions, it is important to use all methods to establish an accurate diagnosis.

Micromorphology and spectroscopic characteristics of organic matter in waterlogged podzols of the upper Amazon basin

In waterlogged environments of the upper Amazon basin, organic matter is a major driver in the podzolisation of clay-depleted laterites, especially through its ability to weather clay minerals and chelate metals. Its structure in eight organic-rich samples collected at the margin and in the centre of the podzolic area of a soil sequence was investigated. The samples illustrate the main steps in the development of waterlogged podzols and belong either to eluviated topsoil A horizons or to illuviated subsoil Bhs, Bh and 2BCs horizons. Organic matter micromorphology was described, and the overall molecular structure of their clay size fractions was assessed using Fourier transform infrared (FTIR) spectroscopy and cross polarization/magic angle spinning (CP/MAS) C-13 nuclear magnetic resonance (NMR). Organic features of the horizons strongly vary both vertically and laterally in the sequence. Topsoil A horizons are dominated by organic residues juxtaposed to clean sands with a major aliphatic contribution. In the subsoil, numerous coatings, characteristic of illuviation processes, are observed in the following horizons: (i) At the margin and bottom parts of the podzolic area, dark brown organic compounds of low aromacity with abundant oxygen-containing groups accumulate in Bhs and 2BCs horizons. Their spectroscopic features agree with the observation of cracked coatings in 2BCs and the presence of organometallic complexes, whose abundance decreases towards low lying positions. (ii) By contrast, black organic compounds of high aromacity with few chelating functions accumulate as coatings and infills in the overlying sandy Bh horizon of well-expressed waterlogged podzols. (c) 2008 Elsevier B.V. All rights reserved.

Synthesis and characterization of solid 2-methoxycinnamylidenepyruvic acid

O ácido 2-metoxicinamalpirúvico (2-MeO-HCP) foi sintetizado e caracterizado por ressonância magnética nuclear (¹H and 13C NMR), espectrometria de massas (MS), espectroscopia na região do infravermelho (FTIR) e calorimetria exploratória diferencial (DSC). A técnica DSC foi usada para determinação da pureza do composto e as principais bandas de absorção na região do infravermelho foram atribuídas utilizando-se o programa GaussView 3.0.

Three-dimensional magnetic resonance reconstruction images before and after surgical therapy of spontaneous canine brain tumors

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

Electrically detected and conventional magnetic resonance investigation of surface and bulk states in polyaniline thin films

Electrically detected magnetic resonance (EDMR) and electron paramagnetic resonance (EPR) were used to investigate emeraldine base polyaniline films. The magnetic susceptibility presented a Curie (localized spins)-Pauli (delocalized spins) transition at 240 K, when we also observed a transition in the dependence of the g factor with temperature (T). Peak-to-peak linewidth decreases with increasing temperature, reflecting that motional narrowing limits the hyperfine and dipolar broadening in this polymer. EDMR spectra could only be observed above 250 K in accordance to EPR results. Surface and bulk transport could be separated and their analysis reflected the effect of magnetic interaction with oxygen. (c) 2007 American Institute of Physics.

New layered double hydroxides intercalated with substituted pyrroles. 1. In situ polymerization of 4-(1H-pyrrol-1-yl)benzoate

The two-dimensional hybrid organic-inorganic materials Zn-2-Cr and Zn-2-Al-LDHs (Layered Double Hydroxides) containing 4-(1H-pyrrol-1yl)benzoate anions as the interlayer anions were synthesized by the co-precipitation method at constant pH followed by subsequent hydrothermal treatment for 72 h. The materials were characterized by PXRD, C-13 CP-MAS NMR, ESR, TGA, and TEM. The basal spacing found by the X-ray diffraction technique is coincident with the formation of bilayers of the intercalated anions. Solid-state C-13 NMR and ESR data strongly suggest the partial in situ polymerization of the 4-(1H-pyrrol-1yl)benzoate anions during coprecipitation. (c) 2006 Elsevier Ltd. All rights reserved.

New layered double hydroxides intercalated with substituted pyrroles. 2. 3-(Pyrrol-1-yl)-propanoate and 7-(pyrrol-1-yl)-heptanoate LDHs

We report the synthesis and characterization of organic-inorganic hybrid materials: Zn-2-Al-LDHs (layered double hydroxides) containing 3-(1H-pyrrol-1-yl)-propanoate and 7-(1H-pyrrol-l-yl)-heptanoate as the interlayer anions. The LDHs were synthesized by the co-precipitation method at constant pH followed by hydrothermal treatment for 72 h. The materials were characterized by PXRD, C-13 CP-MAS NMR, TGA, and ESR. The basal spacing found by PXRD technique is coincident with the formation of bilayers of the intercalated anions. The solid state C-13 NMR showed that the interlayered anions remain identical after intercalation. ESR data suggest that the monomers connect each other in a limited number of guests when a thermal treatment is applied. The inorganic LDH sheets delay the temperature of degradation of the monomers. (c) 2006 Elsevier Ltd. All rights reserved.

Solid-state NMR, ionic conductivity, and thermal studies of lithium-doped siloxane-poly(propylene glycol) organic-inorganic nanocomposites

Hybrid organic-inorganic ionic conductors, also called ormolytes (organically modified electrolytes), were obtained by dissolution of LiClO 4 in siloxane-poly(propylene glycol) matrixes. The dynamic features of these nanocomposites were studied and correlated to their electrical properties. Solid-state nuclear magnetic resonance (NMR) spectroscopy was used to probe the effects of the temperature and nanocomposite composition on the dynamic behaviors of both the ionic species ( 7Li) and the polymer chains ( 13C). NMR, dc ionic conductivity, and DSC results demonstrate that the Li + mobility is strongly assisted by the segmental motion of the polymer chain above its glass transition temperature. The ac ionic conductivity in such composites is explained by use of the random free energy barrier (RFEB) model, which is agreement with their disordered and heterogenous structures. These solid ormolytes are transparent and flexible, and they exhibit good ionic conductivity at room temperature (up to 10 -4 S/cm). Consequently, they are very promising candidates for use in several applications such as batteries, sensors, and electrochromic and photoelectro-chemical devices.