13 resultados para 20-GC 2

em Biblioteca Digital da Produção Intelectual da Universidade de São Paulo (BDPI/USP)


Relevância:

90.00% 90.00%

Publicador:

Resumo:

The leaves of the Pitanga bush (Eugenia uniflora L.) are considered to be effective against many diseases. Extracts from Pitanga leaves have been found to show pronounced anti-inflammatory action and to have antimicrobial and antifungal activities, among other properties. In this work, extracts from Pitanga leaves were obtained by hydrodistillation and by extraction with supercritical carbon dioxide (SC-CO(2)) at three conditions of temperature and pressure. In the SC-CO(2) extractions also were collected the components that are lost with the CO(2) in the exit of the system using Porapak-Q polymer trap. All extracts were analyzed by gas chromatography-mass spectrometry (GC-MS). Thirty-nine compounds were found in the extracts and twenty-six were identified. The main components identified in the extracts in decreasing quantitative order were: curzerene, germacrene B, C(15)H(20)O(2) and beta-elemene for hydrodistillation; C(15)H(20)O(2) and curzerene for SC-CO(2) extracts and 3-hexen-1-ol, curzerene, C(15)H(20)O(2), beta-elemene and germacrene B for SC-CO(2) extracts captured in Porapak-Q. PRACTICAL APPLICATIONS The natural extracts are a potential source of compounds possessing biological activities. They can be used in foods, pharmaceutics and cosmetics. Pitanga is an exotic fruit from Brazil and extracts from its leaves have been used against many diseases in Brazilian folk medicine. Supercritical extraction is an interesting process for the production of natural extracts because it is a clean process and the knowledge of composition of extracts is crucial for the identification of the probable active components.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In this paper, we report the measurement of Rb(2) molecule formation rate constant due to a two body process in a magneto-optical trap as a function of the sample temperature. The ground state molecules are detected by two-photon ionization, through the intermediate a(3)Sigma(+)(u) -> 2(3)Pi(g) molecular band. Our results show that the Rb(2) molecules formed in the MOT could be due to a wave shape resonance, which enhances the molecule formation rate. This effect may be used to enhance the molecule production; and therefore it maybe important to future experiments involving production and trapping of cold ground state molecules.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The fragmentation mechanisms of singlet oxygen [O(2) ((1)Delta(g))]-derived oxidation products of tryptophan (W) were analyzed using collision-induced dissociation coupled with (18)O-isotopic labeling experiments and accurate mass measurements. The five identified oxidized products, namely two isomeric alcohols (trans and cis WOH), two isomeric hydroperoxides (trans and cis WOOH), and N-formylkynurenine (FMK), were shown to share some common fragment ions and losses of small neutral molecules. Conversely, each oxidation product has its own fragmentation mechanism and intermediates, which were confirmed by (18)O-labeling studies. Isomeric WOH lost mainly H(2)O + CO, while WOOH showed preferential elimination of C(2)H(5)NO(3) by two distinct mechanisms. Differences in the spatial arrangement of the two isomeric WOHs led to differences in the intensities of the fragment ions. The same behavior was also found for trans and cis WOOH. FMK was shown to dissociate by a diverse range of mechanisms, with the loss of ammonia the most favored route. MS/MS analyses, (18)O-labeling, and H(2)(18)O experiments demonstrated the ability of FMK to exchange its oxygen atoms with water. Moreover, this approach also revealed that the carbonyl group has more pronounced oxygen exchange ability compared with the formyl group. The understanding of fragmentation mechanisms involved in O(2) ((1)Delta(g))-mediated oxidation of W provides a useful step toward the structural characterization of oxidized peptides and proteins. (J Am Soc Mass Spectrom 2009, 20, 188-197) (C) 2009 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The performance of a polymer electrolyte membrane fuel cell (PEMFC) operating on a simulated hydrocarbon reformate is described. The anode feed stream consisted of 80% H(2),similar to 20% N(2), and 8 ppm hydrogen sulfide (H(2)S). Cell performance losses are calculated by evaluating cell potential reduction due to H(2)S contamination through lifetime tests. It is found that potential, or power, loss under this condition is a result of platinum surface contamination with elemental sulfur. Electrochemical mass spectroscopy (EMS) and electrochemical techniques are employed, in order to show that elemental sulfur is adsorbed onto platinum, and that sulfur dioxide is one of the oxidation products. Moreover, it is demonstrated that a possible approach for mitigating H(2)S poisoning on the PEMFC anode catalyst is to inject low levels of air into the H(2)S-contaminated anode feeding stream. (C) 2011 Elsevier B.V. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We describe 17 children with nocturnal or early-morning seizures who were switched to a proportionally higher evening dose of antiepileptic drugs and were retrospectively reviewed for seizure outcome and side effects. Of 10 children with unknown etiology, clinical presentation was consistent with nocturnal frontal lobe epilepsy (NFLE) in 5 and benign epilepsy with centrotemporal spikes (BECTS) in 3. After a mean follow-up of 5.3 months, 15 patients were classified as responders: 11 of these became seizure free (5 NFLE, 1 BECTS, 5 with structural lesions) and 4 (2 BECTS, 2 with structural lesions) experienced 75-90% reductions in seizures. Among two nonresponders, seizures in one had failed to resolve with epilepsy surgery. Nine subjects (53%) received monotherapy after dose modification, and none presented with worsening of seizures. Two complained of transient side effects (fatigue/somnolence). Differential dosing led to seizure freedom in 64.7% (11/17) of patients, and 88.2% (15/17) experienced >= 50% reductions in seizures. (C) 2010 Elsevier Inc. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The objective of the current study was to analyze the effects of rhinoseptoplasty on internal nasal dimensions and speech resonance of individuals with unilateral cleft lip and palate, estimated by acoustic rhinometry and nasometry, respectively. Twenty-one individuals (aged 15-46 years) with previously repaired unilateral cleft lip and palate were analyzed before (PRE), and 6 to 9 (POST1) and 12 to 18 months (POST2) after surgery. Acoustic rhinometry was used to measure the cross-sectional areas (CSAs) of segments corresponding to the nasal valve (CSA1), anterior portion (CSA2), and posterior portion (CSA3) of the lower turbinate, and the volumes at the nasal valve (V1) and turbinate (V2) regions at cleft and noncleft sides, before and after nasal decongestion with a topical vasoconstrictor. Nasometry was used to evaluate speech nasalance during the reading of a set of sentences containing nasal sounds and other devoid of nasal sounds. At the cleft side, before nasal decongestion, there was a significant increase (P < 0.05) in mean CSA1 and V1 values at POST1 and POST2 compared with PRE. After decongestion, increased values were also observed for CSA2 and V2 at POST2. No significant changes were observed at the noncleft side. Mean nasalance values at PRE, POST1, an POST2 were not different from each other in both oral and nasal sentences. The measurement of CSAs and volumes by acoustic rhinometry revealed that rhinoseptoplasty provided, in most cases analyzed, a significant increase in nasal patency, without concomitant changes in speech resonance, as estimated by nasalance assessment.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Aim: Changes in skeletal muscle morphology and metabolism are associated with limited functional capacity in heart failure, which can be attenuated by neuromuscular electrical stimulation (ES). The purpose of the present study was to analyse the effects of ES upon GLUT-4 protein content, fibre structure and vessel density of the skeletal muscle in a rat model of HF subsequent to myocardial infarction. Methods: Forty-four male Wistar rats were assigned to one of four groups: sham (S), sham submitted to ES (S+ES), heart failure (HF) and heart failure submitted to ES (HF+ES). The rats in the ES groups were submitted to ES of the left leg during 20 days (2.5 kHz, once a day, 30 min, duty cycle 50%- 15 s contraction/15 s rest). After this period, the left tibialis anterior muscle was collected from all the rats for analysis. Results: HF+ES rats showed lower values of lung congestion when compared with HF rats (P = 0.0001). Although muscle weight was lower in HF rats than in the S group, thus indicating hypotrophy, 20 days of ES led to their recovery (P < 0.0001). In both groups submitted to ES, there was an increase in muscle vessel density (P < 0.04). Additionally, heart failure determined a 49% reduction in GLUT-4 protein content (P < 0.03), which was recovered by ES (P < 0.01). Conclusion: In heart failure, ES improves morphological changes and raises GLUT-4 content in skeletal muscle.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The ccpA gene was inactivated in the polyhydroxybutyrate (PHB)-producing strain Bacillus sp. MA3.3 in order to reduce glucose catabolite repression over pentoses and develop improved bacterial strains for the production of PHB from lignocellulosic hydrolysates. Mutant Bacillus sp. MSL7 Delta CcpA are unable to grow on glucose and ammonia as sole carbon and nitrogen sources, respectively. Supplementation of glutamate as the nitrogen source or the substitution of the carbon source by xylose allowed the mutant to partially recover its growth performance. RT-PCR showed that CcpA stimulates the expression of the operon (gltAB), responsible for ammonia assimilation via glutamate in Bacillus sp. MA3.3. Moreover, it was demonstrated that the supplementation of xylose or glutamate was capable of stimulating gltAB operon expression independently of CcpA. In PHB production experiments in mineral media, it has been observed that the glucose catabolite repression over the pentoses was partially released in MSL7. Although the carbohydrate consumption is faster in the ccpA mutant, the biomass and PHB biosynthesis are lower, even with supplementation of glutamate. This is attributed to an increase of acetyl-CoA flux towards the tricarboxylic acid cycle observed in the mutant. Copyright (C) 2011 S. Karger AG, Basel

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The highly hydrophobic fluorophore Laurdan (6-dodecanoyl-2-(dimethylaminonaphthalene)) has been widely used as a fluorescent probe to monitor lipid membranes. Actually, it monitors the structure and polarity of the bilayer surface, where its fluorescent moiety is supposed to reside. The present paper discusses the high sensitivity of Laurdan fluorescence through the decomposition of its emission spectrum into two Gaussian bands, which correspond to emissions from two different excited states, one more solvent relaxed than the other. It will be shown that the analysis of the area fraction of each band is more sensitive to bilayer structural changes than the largely used parameter called Generalized Polarization, possibly because the latter does not completely separate the fluorescence emission from the two different excited states of Laurdan. Moreover, it will be shown that this decomposition should be done with the spectrum as a function of energy, and not wavelength. Due to the presence of the two emission bands in Laurdan spectrum, fluorescence anisotropy should be measured around 480 nm, to be able to monitor the fluorescence emission from one excited state only, the solvent relaxed state. Laurdan will be used to monitor the complex structure of the anionic phospholipid DMPG (dimyristoyl phosphatidylglycerol) at different ionic strengths, and the alterations caused on gel and fluid membranes due to the interaction of cationic peptides and cholesterol. Analyzing both the emission spectrum decomposition and anisotropy it was possible to distinguish between effects on the packing and on the hydration of the lipid membrane surface. It could be clearly detected that a more potent analog of the melanotropic hormone alpha-MSH (Ac-Ser(1)-Tyr(2)-Ser(3)-Met(4)-Glu(5)-His(6)-Phe(7)-Arg(8)-Trp(9)-Gly(10)-Lys(11)-Pro(12)-Val(13)-NH(2)) was more effective in rigidifying the bilayer surface of fluid membranes than the hormone, though the hormone significantly decreases the bilayer surface hydration.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We investigate the critical behavior of a stochastic lattice model describing a predator-prey system. By means of Monte Carlo procedure we simulate the model defined on a regular square lattice and determine the threshold of species coexistence, that is, the critical phase boundaries related to the transition between an active state, where both species coexist and an absorbing state where one of the species is extinct. A finite size scaling analysis is employed to determine the order parameter, order parameter fluctuations, correlation length and the critical exponents. Our numerical results for the critical exponents agree with those of the directed percolation universality class. We also check the validity of the hyperscaling relation and present the data collapse curves.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

We studied the P-T-t evolution of a mid-crustal igneous-metamorphic segment of the Famatinian Belt in the eastern sector of the Sierra de Velasco during its exhumation to the upper crust. Thermobarometric and geochronological methods combined with field observations permit us to distinguish three tectonic levels. The deepest Level I is represented by metasedimentary xenoliths and characterized by prograde isobaric heating at 20-25 km depth. Early/Middle Ordovician granites that contain xenoliths of Level I intruded in the shallower Level II. The latter is characterized by migmatization coeval with granitic intrusions and a retrograde isobaric cooling P-T path at 14-18 km depth. Level II was exhumed to the shallowest supracrustal Level III, where it was intruded by cordierite-bearing granites during the Middle/Late Ordovician and its host-rock was locally affected by high temperature-low pressure HT/LP metamorphism at 8-10 km depth. Level III was eventually intruded by Early Carboniferous granites after long-term slow exhumation to 6-7 km depth. Early/Middle Ordovician exhumation of Level II to Level III (Exhumation Period I,0.25-0.78 mm/yr) was faster than exhumation of Level III from the Middle/Late Ordovician to the Lower Carboniferous (Exhumation Period II, 0.01-0.09 mm/yr). Slow exhumation rates and the lack of regional evidence of tectonic exhumation suggest that erosion was the main exhumation mechanism of the Famatinian Belt. Widespread slow exhumation associated with crustal thickening under a HT regime suggests that the Famatinian Belt represents the middle crust of an ancient Altiplano-Puna-like orogen. This thermally weakened over-thickened Famatinian crust was slowly exhumed mainly by erosion during similar to 180 Myr. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.

Relevância:

80.00% 80.00%

Publicador:

Resumo:

Bendadaite, ideally Fe(2+)Fe(2)(3+)(AsO(4))(2)(OH)(2 center dot).4H(2)O, is a new member of the arthurite group It was found as a weathering product of arsenopyrite on a single hand specimen from the phosphate pegmatite Bendada. central Portugal (type locality) Co-type locality is the granite pegmatite of La via do Almerindo (Almerindo mine), Linopolis, Divmo das Laranjeiras county, Minas Gerais, Brazil Further localities are the Vein Negra mine, Copiapo province, Chile, mid-East, Bou Azzer district, Morocco, and Para Inferida yard, Fenugu Sibirt mine, Gonnosfanadiga, Medio Campidano Province, Sardinia. Italy Type bendadaite occurs as blackish green to dark brownish tufts (<0 1 mm long) and flattened radiating aggregates. in intimate association with an intermediate member of the scorodite-mansfieldite series It is monoclinic. space group P2(l/c). with a = 10 239(3) angstrom. b = 9 713(2) angstrom, c = 5 552(2) angstrom. beta = 94 11(2)degrees. = 550 7(2) angstrom(3). Z = 2 Electron-microprobe analysis yielded (wt %). CaO 0 04, MnO 0 03. CuO 006, ZnO 004. Fe(2)O(3) (total) 43 92, Al(2)O(3) 115. SnO(2) 0 10, As(2)O(5) 43 27. P(2)O(5) 1 86, SO(3) 0.03 The empirical formula is (Fe(0 52)(2+)Fe(0 32)(3+)rectangle(0 16))(Sigma 1 00)(Fe(1 89)(3+)Al(0 11))(Sigma 2 00)(As(1 87)P(0 13))(Sigma 2 00)O(8)(OH)(2 00) 4H(2)O based. CM 2(As,P) and assuming ideal 80, 2(OH), 4H2O and complete occupancy of the ferric on site by Fe(3+) and Al Optically, bendadaite is biaxial, positive, 2V(est) = 85+/-4 degrees, 2V(eale) = 88 degrees, with alpha 1 734(3). 13 1 759(3), 7 1 787(4) Pleochrosim is medium strong X pale reddish brown. Y yellowish brown, Z dark yellowish brown. absorption Z > V > X, optical dispersion weak, r > v. Optical axis plane Is parallel to (010), with X approximately parallel to a and Z nearly parallel to c Bendadaite has vitreous to sub-adamantine luster, is translucent and non-fluorescent It is brittle, shows irregular fracture and a good cleavage parallel to 1010} 3 15 0 10 g/cm(3), 3 193 g/cm3 (for the empirical formula) The five strongest powder diffraction lines [d in angstrom (I)(hkl] are 10 22 (10)(100), 7 036 (8)(110), 4 250 (5)(11 I), 2 865 (4)(311), 4 833 (3)(020,011) The d spacings are very similar to those of its Zn analogue, ojelaite The crystal structure of bendadaite was solved and refined using a crystal from the co-type locality with the composition (Fe(0 95)(2+)rectangle(0 05))(Sigma 1 00)(Fe(1 80)(3+)Al(0 20))Sigma(2 00)(As(1 48)P(0 52))(Sigma 2 00)O(8)) (OH)(2) 4H(2)O (R = 16%) and confirms an arthurite-type atomic arrangement

Relevância:

80.00% 80.00%

Publicador:

Resumo:

The coastal plains of the States of Parana and Santa Catarina, in Southern Brazil, were first settled around 6000 B.P. by shellmound builders, a successful fisher-hunter-gatherer population that inhabited the coastal lowlands practically unchanged for almost five thousand years. Shellmounds were typically occupied as residential sites as well as cemeteries, and are usually associated with rich alimentary zones. Around 1200 B.P., the first evidence of ceramics brought from the interior is found in coastal areas, and together with ceramics there is a progressive abandonment of shellmound construction in favor of flat cold shallow sites. Here we consider if these changes were reflected in the postmarital residence practice of coastal groups, i.e., if the arrival or intensification of contact with groups from the interior resulted in changes in this aspect of social structure among the coastal groups. To test the postmarital residence practice we analyzed within-group variability ratios between males and females, following previous studies on the topic. and between-group, correlations between Mahalanobis distances and geographic distances. The results suggest that in the pre-ceramic series a matrilocal, postmarital residential system predominated, while in the ceramic period there was a shift toward patrilocality. This favors the hypothesis that the changes experienced by coastal groups after 1200 B.P. affected not only their economy and material culture, but important aspects of their sociopolitical organization as well.