934 resultados para 2-DIMENSIONAL STRAIN
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We prove a coordinatization theorem for noncommutative Jordan superalgebras of degree n > 2, describing such algebras. It is shown that the symmetrized Jordan superalgebra for a simple finite-dimensional noncommutative Jordan superalgebra of characteristic 0 and degree n > 1 is simple. Modulo a ""nodal"" case, we classify central simple finite-dimensional noncommutative Jordan superalgebras of characteristic 0.
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Let G = Z/a x(mu) (Z/b x TL(2)(F(p))) and X(n) be an n-dimensional CW-complex with the homotopy type of the n-sphere. We determine the automorphism group Aut(G) and then compute the number of distinct homotopy types of spherical space forms with respect to free and cellular G-actions on all CW-complexes X(2dn - 1), where 2d is a period of G. Next, the group E(X(2dn - 1)/alpha) of homotopy self-equivalences of spherical space forms X(2dn - 1)/alpha, associated with such G-actions alpha on X(2dn - 1) are studied. Similar results for the rest of finite periodic groups have been obtained recently and they are described in the introduction. (C) 2009 Elsevier B.V. All rights reserved.
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One may construct, for any function on the integers, an irreducible module of level zero for affine sl(2) using the values of the function as structure constants. The modules constructed using exponential-polynomial functions realize the irreducible modules with finite-dimensional weight spaces in the category (O) over tilde of Chari. In this work, an expression for the formal character of such a module is derived using the highest weight theory of truncations of the loop algebra.
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A soil microorganism identified as Bacillum megaterium was found to produce several antibiotics substances after growth for 20 h at 37A degrees C in a mineral culture medium. Analysis both by electron spray ionization (ESI) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) identified these substances as lipopeptides. Predominant peaks at m/z 1,041 and m/z 1,065 revealed ions which are compatible with surfactins and lichenysins, respectively. Two other ions m/z 1,057 and m/z 1,464 were further studied by collision-induced dissociation (CID) unveiling an iturin A at the first and fengycins A and B at the second m/z peaks. The CID spectrum of the m/z 1,464 ion also suggests the existence of fengycins A and B variants in which Ile was changed to Val in the position 10 of the peptide moiety. Raw mixtures of all these compounds were also assayed for antibiotic features. The data enlighten the unusual diversity of the lipopeptide mixture produced by a sole Bacillus species.
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The use of whole cells of micro-organisms to bring about the biotransformation of an organic compound offers a number of advantages, but problems caused by enzymatic Promiscuity may be encountered upon With Substrates hearing more than one functional group. A one-pot screening method, in which whole fungal cells were incubated with a Mixture of 4-rnethylcyclohexanone I and phenyl methyl Sulfide 2, has been employed to determine the chemoselectivity of various biocatalysts. The hyphomycetes, Aspergillus terreus CCT 3320 and A. terreus URM 3571, catalysed the oxidation of 2 accompanied by the reduction of I to 4-methylcyclohexanol 1a and, for strain A. terreus CCT 3320, the Baeyer-Villiger oxidation of 1. The Basidomycetes, Trametes versicolor CCB 202, Pycnoporus sanguineus CCB 501 and Trichaptum byssogenum CCB 203, catalysed the oxidation of 2 and the reduction 1, but no Baeyer-Villiger reaction products were detected. In contrast. Trametes rigida CCB 285 catalysed the biotransformation of 1 to 1a, exclusively, in the absence of any detectable Sulfide oxidation reactions. The chemoselective reduction Of (+/-)-2-(phenylthio)cyclohexanone 3 by T. rigida CCB 285 afforded exclusively the (+)-cis-(1R,2S) and (+)-trans-(1S,2S) diastereoisomers of 2-(phenylthio)cyclohexan-1-ol 3a in moderate yields (13% and 27%, respectively) and high enantiomeric excesses (>98%). Chemoselective screening for the reduction of a ketone and/or the oxidation Of a Sulfide group in one pot by whole cells of micro-organisms represents an attractive technique with applications in the development of synthesis of complex molecule hearing different functional groups. (C) 2008 Published by Elsevier Ltd.
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The conformational features of three 2-sulphur-substituted cyclohexanone derivatives, which differ in the number of sulphur-bound oxygen atoms, i.e. zero (I), one (II) and two (III), were investigated by single crystal X-ray crystallography and geometry optimized structures determined using Hartree-Fock method. In each of (I)-(III) an intramolecular S center dot center dot center dot O(carbonyl) interaction is found with the magnitude correlated with the oxidation state of the sulphur atom, i.e. 2.838(3) angstrom in (I) to 2.924(2) angstrom in (II) to 3.0973(18) angstrom in (III). There is an inverse relationship between the strength of this interaction and the magnitude of the carbonyl bond. The supramolecular aggregation patterns are primarily determined by C-H center dot center dot center dot O contacts and are similarly influenced by the number of oxygen atoms in the molecular structures. Thus, a supramolecular chain is found in the crystal structure of (I). With an additional oxygen atom available to participate in C-H center dot center dot center dot O interactions, as in (II), a two-dimensional array is found. Finally, a three-dimensional network is found for (III). Despite there being differences in conformations between the experimental structures and those calculated in the gas-phase, the S center dot center dot center dot O interactions persist. The presence of intermolecular C-H center dot center dot center dot O interactions involving the cyclohexanone-carbonyl group in the solid-state, disrupts the stabilising intramolecular C-H center dot center dot center dot O interaction in the energetically-favoured conformation. (I): C(12)H(13)NO(3)S, triclinic space group P (1) over bar with a = 5.392(3) angstrom b = 10.731(6) angstrom, c = 11.075(6) angstrom, alpha = 113.424(4)degrees, beta = 94.167(9)degrees, gamma = 98.444(6)degrees, V = 575.5(6) angstrom(3), Z = 2, R(1) = 0.052; (II): C(12)H(13)NO(4)S, monoclinic P2(1)/n, a = 7.3506(15) angstrom, b = 6.7814(14) angstrom, c = 23.479(5) angstrom, beta = 92.94(3)degrees, V = 1168.8(4) angstrom(3), Z = 4, R(1) = 0.046; (III): C(12)H(13)NO(5)S, monoclinic P2(1)/c, a = 5.5491(11) angstrom, b = 24.146(3) angstrom, c = 11.124(3) angstrom, beta = 114.590(10)degrees, V = 1355.3(5) angstrom(3), Z = 4, R(1) = 0.051.
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A disfunção autonômica está associada com aumento da mortalidade em pacientes diabéticos, especialmente naqueles com doença cardiovascular. Neuropatia periférica, mau controle glicêmico, dislipidemia e hipertensão são alguns dos fatores de risco para o desenvolvimento de doença vascular periférica (DVP) nestes pacientes. O objetivo deste estudo foi avaliar os fatores de risco associados com a presença de DVP em pacientes com DM tipo 2. Um estudo transversal foi realizado em 84 pacientes com DM tipo 2 ( 39 homens, idade média de 64,9 ± 7,5 anos). Os pacientes foram submetidos a uma avaliação clínica e laboratorial. A presença de DVP foi definida, utilizando-se um um aparelho manual de ultrasom com doppler (índice perna-braço < 0,9). A atividade autonômica foi avaliada através da análise da variabilidade da freqüência cardíaca (HRV) por métodos no domínio do tempo e da freqüência (análise espectral), e pelo mapa de retorno tridimensional durante o período do dia e da noite. Para a análise da HRV, um eletrocardiograma de 24 horas foi gravado e as fitas analisadas em um analisador de Holter Mars 8000 (Marquete). A potência espectral foi quantificada pela área em duas bandas de freqüência: 0,04-0,15 Hz – baixa freqüência (BF), 0,015-0,5 Hz – alta freqüência (AF). A razão BF/AF foi calculada em cada paciente. O mapa de retorno tridimensional foi construído através de um modelo matemático onde foram analisados os intervalos RR versus a diferença entre os intervalos RR adjacentes versus o número de contagens verificadas, e quantificado por três índices refletindo a modulação simpática (P1) e vagal (P2 e P3). DVP estava presente em 30 (36%) pacientes. Na análise univariada, pacientes com DVP apresentaram índices que refletem a modulação autonômica (análise espectral) diminuídos quando comparados aos pacientes sem DVP, respectivamente: BF = 0,19 ± 0,07 m/s2 vs. 0,29 ± 0,11 m/s2 P = 0,0001; BF/AF = 1,98 ± 0,9 m/s2 vs. 3,35 ± 1,83 m/s2 p = 0,001. Além disso, o índice que reflete a atividade simpática no mapa de retorno tridimensional (P1), foi mais baixo em pacientes com DVP (61,7 ± 9,4 vs. 66,8 ± 9,7 unidades arbitrárias, P = 0,04) durante a noite, refletindo maior ativação simpática neste período. Estes pacientes também apresentavam uma maior duração do diabetes (20 ± 8,1 vs. 15,3 ± 6,7 anos, P = 0,006), níveis de pressão arterial sistólica (154 ± 20 vs. 145 ± 20 mmHg, P = 0,04), razão cintura-quadril ( 0,98 ± 0,09 vs.0,92 ± 0,08, P = 0,01), e níveis de HbA1c mais elevados (7,7 ± 1,6 vs. 6,9 ± 1,7 %, P = 0,04), bem como valores de triglicerídeos ( 259 ± 94 vs. 230 ± 196 mg/dl, P= 0,03) e de excreção urinária de albumina ( 685,5 ± 1359,9 vs. 188,2 ± 591,1 μ/min, P = 0,02) superiores aos dos pacientes sem DVP.. Nos pacientes com DVP observou-se uma presença aumentada de nefropatia diabética (73,3% vs. 29,6% P = 0,0001), de retinopatia (73,3% vs. 44,4% P = 0,02) e neuropatia periférica (705 vs. 35,1% P = 0,006). Os grupos não diferiram quanto à idade, índice de massa corporal, tabagismo e presença de doença arterial coronariana. Na análise logística multivariada, a DVP permaneceu associada com a disfunção autonômica, mesmo após ter sido controlada pela pressão arterial sistólica, duração do DM, HbA1c, triglicerídeos e excreção urinária de albumina. Concluindo, pacientes com DVP e DM tipo 2 apresentam índices que refletem a modulação autonômica diminuídos, o que pode representar um fator de risco adicional para o aumento da mortalidade nestes pacientes.
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An analytical methodology based on headspace solid phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography—time-of-flight mass spectrometry (GC × GC–ToFMS) was developed for the identification and quantification of the toxic contaminant ethyl carbamate (EC) directly in fortified wines. The method performance was assessed for dry/medium dry and sweet/medium sweet model wines, and for quantification purposes, calibration plots were performed for both matrices using the ion extraction chromatography (IEC) mode (m/z 62). Good linearity was obtained with a regression coefficient (r2) higher than 0.981. A good precision was attained (R.S.D. <20%) and low detection limits (LOD) were achieved for dry (4.31 μg/L) and sweet (2.75 μg/L) model wines. The quantification limits (LOQ) and recovery for dry wines were 14.38 μg/L and 88.6%, whereas for sweet wines were 9.16 μg/L and 99.4%, respectively. The higher performance was attainted with sweet model wine, as increasing of glucose content improves the volatile compound in headspace, and a better linearity, recovery and precision were achieved. The analytical methodology was applied to analyse 20 fortified Madeira wines including different types of wine (dry, medium dry, sweet, and medium sweet) obtained from several harvests in Madeira Island (Portugal). The EC levels ranged from 54.1 μg/L (medium dry) to 162.5 μg/L (medium sweet).
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In this study the effect of the cultivar on the volatile profile of five different banana varieties was evaluated and determined by dynamic headspace solid-phase microextraction (dHS-SPME) combined with one-dimensional gas chromatography–mass spectrometry (1D-GC–qMS). This approach allowed the definition of a volatile metabolite profile to each banana variety and can be used as pertinent criteria of differentiation. The investigated banana varieties (Dwarf Cavendish, Prata, Maçã, Ouro and Platano) have certified botanical origin and belong to the Musaceae family, the most common genomic group cultivated in Madeira Island (Portugal). The influence of dHS-SPME experimental factors, namely, fibre coating, extraction time and extraction temperature, on the equilibrium headspace analysis was investigated and optimised using univariate optimisation design. A total of 68 volatile organic metabolites (VOMs) were tentatively identified and used to profile the volatile composition in different banana cultivars, thus emphasising the sensitivity and applicability of SPME for establishment of the volatile metabolomic pattern of plant secondary metabolites. Ethyl esters were found to comprise the largest chemical class accounting 80.9%, 86.5%, 51.2%, 90.1% and 6.1% of total peak area for Dwarf Cavendish, Prata, Ouro, Maçã and Platano volatile fraction, respectively. Gas chromatographic peak areas were submitted to multivariate statistical analysis (principal component and stepwise linear discriminant analysis) in order to visualise clusters within samples and to detect the volatile metabolites able to differentiate banana cultivars. The application of the multivariate analysis on the VOMs data set resulted in predictive abilities of 90% as evaluated by the cross-validation procedure.
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The establishment of potential age markers of Madeira wine is of paramount significance as it may contribute to detect frauds and to ensure the authenticity of wine. Considering the chemical groups of furans, lactones, volatile phenols, and acetals, 103 volatile compounds were tentatively identified; among these, 71 have been reported for the first time in Madeira wines. The chemical groups that could be used as potential age markers were predominantly acetals, namely, diethoxymethane, 1,1-diethoxyethane, 1,1-diethoxy-2-methyl-propane, 1-(1-ethoxyethoxy)-pentane, trans-dioxane and 2-propyl-1,3-dioxolane, and from the other chemical groups, 5-methylfurfural and cis-oak-lactone, independently of the variety and the type of wine. GC × GC-ToFMS system offers a more useful approach to identify these compounds compared to previous studies using GC−qMS, due to the orthogonal systems, that reduce coelution, increase peak capacity and mass selectivity, contributing to the establishment of new potential Madeira wine age markers. Remarkable results were also obtained in terms of compound identification based on the organized structure of the peaks of structurally related compounds in the GC × GC peak apex plots. This information represents a valuable approach for future studies, as the ordered-structure principle can considerably help the establishment of the composition of samples. This new approach provides data that can be extended to determine age markers of other types of wines.
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Allergic asthma represents an important public health issue, most common in the paediatric population, characterized by airway inflammation that may lead to changes in volatiles secreted via the lungs. Thus, exhaled breath has potential to be a matrix with relevant metabolomic information to characterize this disease. Progress in biochemistry, health sciences and related areas depends on instrumental advances, and a high throughput and sensitive equipment such as comprehensive two-dimensional gas chromatography–time of flight mass spectrometry (GC × GC–ToFMS) was considered. GC × GC–ToFMS application in the analysis of the exhaled breath of 32 children with allergic asthma, from which 10 had also allergic rhinitis, and 27 control children allowed the identification of several hundreds of compounds belonging to different chemical families. Multivariate analysis, using Partial Least Squares-Discriminant Analysis in tandem with Monte Carlo Cross Validation was performed to assess the predictive power and to help the interpretation of recovered compounds possibly linked to oxidative stress, inflammation processes or other cellular processes that may characterize asthma. The results suggest that the model is robust, considering the high classification rate, sensitivity, and specificity. A pattern of six compounds belonging to the alkanes characterized the asthmatic population: nonane, 2,2,4,6,6-pentamethylheptane, decane, 3,6-dimethyldecane, dodecane, and tetradecane. To explore future clinical applications, and considering the future role of molecular-based methodologies, a compound set was established to rapid access of information from exhaled breath, reducing the time of data processing, and thus, becoming more expedite method for the clinical purposes.
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We have studied the universal conductance fluctuations (UCF) due to quantum interface in a two-dimensional electron gas (2DEG) grown on the substrates with pre-patterned, sub-micron wires. The dependence of UCF on the angle between the direction of the magnetic field and the substrate has been investigated. We found, that magnetoresistance traces for different angles are completely uncorrelated. A non-planar character of electron motion is responsible for these angular conductance fluctuations. We compared the experimental results with a simple geometrical model.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This work introduces a new method for environment mapping with three-dimensional information from visual information for robotic accurate navigation. Many approaches of 3D mapping using occupancy grid typically requires high computacional effort to both build and store the map. We introduce an 2.5-D occupancy-elevation grid mapping, which is a discrete mapping approach, where each cell stores the occupancy probability, the height of the terrain at current place in the environment and the variance of this height. This 2.5-dimensional representation allows that a mobile robot to know whether a place in the environment is occupied by an obstacle and the height of this obstacle, thus, it can decide if is possible to traverse the obstacle. Sensorial informations necessary to construct the map is provided by a stereo vision system, which has been modeled with a robust probabilistic approach, considering the noise present in the stereo processing. The resulting maps favors the execution of tasks like decision making in the autonomous navigation, exploration, localization and path planning. Experiments carried out with a real mobile robots demonstrates that this proposed approach yields useful maps for robot autonomous navigation