Artigos em revistas internacionais
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- 13C solid-state nuclear magnetic resonance and Fourier transform infrared studies of the thermal decomposition of corkPublication . Neto, C. Pascoal; Rocha, J.; Gil, A.; Cordeiro, N.; Esculcas, A.P.; Rocha, S.; Delgadillo, I.; De Jesus, J.D.Pedrosa; Correia, A.J.FerrerThe thermal decomposition of cork has been studied by Fourier transform infrared (FTIR) spectroscopy and 13C solid-state nuclear magnetic resonance (NMR) spectroscopy with cross-polarization and magic-angle spinning (CP-MAS), high-power ‘H decoupling (HPDEC) and cross-polarization depolarization-polarization (CPDP). Waxes and other soluble components of cork begin to decompose at ca. 150°C. This is accompanied by partial decomposi tion of suberin, probably initiated at the points of attachment to the cell wall. The carbohydrates begin to decompose at ca. 200°C. The decomposition of lignin begins at 250-3OO”C, while suberin undergoes further degradation. Significant amounts of coke are formed in the process. At 400°C cork has been transformed into coke with traces of partially decomposed suberin. The thermal decomposition of cork is dependent on the calcination time, particularly in the 200-350°C range.
- 3,7-Bis(dialkylamino)phenothiazin-5-ium derivatives: biomedical applications and biological activityPublication . Moura, J. C.; Cordeiro, N.The light-induced reactions of 3,7-bis(dialkylamino)phenothiazin-5-ium compounds with biological substrates are briefly discussed. Their biomedical applications, in particular those related with biological staining, interaction with proteins and antiviral, antibacterial and antitumour activity are reviewed.
- 3-Hydroxy-4,5-dimethyl-2(5H)-furanone levels in fortified Madeira wines: Relationship to sugar contentPublication . Câmara, José Sousa; Marques, José C.; Alves, Maria Arminda; Ferreira, António C. SilvaThe maturation of Madeira wines usually involves exposure to relatively high temperatures and humidity levels >70%, which affect the aroma and flavor composition and lead to the formation of the typical and characteristic bouquet of these wines. To estimate the levels of sotolon [3-hydroxy4,5-dimethyl-2(5 H )-furanone] and their behavior over time, 86 aged Madeira wines samples (1-25 years old), with different sugar concentrations, respectively, 90 g L-1 for Boal, 110 g L-1 for Malvazia, 25 g L -1 for Sercial, and 65 g L-1 for Verdelho varieties, were analyzed. Isolation was performed by liquid-liquid extraction with dichloromethane followed by chromatographic analysis by GC-MS. The reproducibility of the method was found to be 4.9%. The detection and quantification limits were 1.2 and 2.0 µgL-1, respectively. The levels of sotolon found ranged from not detected to 2000 µgL-1 for wines between 1 and 25 years old. It was observed that during aging, the concentration of sotolon increased with time in a linear fashion ( r ) 0.917). The highest concentration of sotolon was found in wines with the highest residual sugar contents, considering the same time of storage. The results show that there is a strong correlation between sotolon and sugar derivatives: furfural, 5-methylfurfural, 5-hydroxymethylfurfural, and 5-ethoxymethylfurfural. These compounds are also well correlated with wine aging. These findings indicate that the kinetics of sotolon formation is closely related with residual sugar contents, suggesting that this molecule may come from a component like sugar.
- 3D modelling of heating of thermionic cathodes by high-pressure arc plasmasPublication . Benilov, M. S.; Carpaij, M.; Cunha, M. D.Numerical investigation of steady-state interaction of a high-pressure argon plasma with a cylindrical tungsten cathode is reported. A whole ‘zoo’ of very diverse modes of current transfer is revealed. Detailed results are given for the first five (three-dimensional) 3D spot modes, four of them branching off from the diffuse mode and one from the first axially symmetric spot mode. Divergences in the general pattern of solutions, which have been present in preceding works, are resolved. Hypotheses on stability of steady-state solutions, available in the literature, are analysed. It is found that these hypotheses provide an explanation of the fact that the transition between diffuse and spot modes is difficult to reproduce in the experiment but they do not explain the indication that it is the low-voltage branch of the first 3D spot mode that seems to occur in the experiment. Thus, the question of stability of steady-state solutions remains open: an accurate stability analysis, as well as additional experimental information is required.
- 4,4′-[Thiophene-2,5-diylbis(ethyne-2,1-diyl)]dibenzonitrilePublication . Figueira, João; Vertlib, Viatslav; Rodrigues, João; Nättinen, Kalle; Rissanen, KariIn the solid state, the title compound, C(22)H(10)N(2)S, forms centrosymmetric dimers by pairs of non-classical C-H⋯S hydrogen bonds linking approximately coplanar mol-ecules. The benzene ring involved in this inter-action makes a dihedral angle of only 7.21 (16)° with the thio-phene ring, while the other benzene ring is twisted somewhat out of the plane, with a dihedral angle of 39.58 (9)°. The hydrogen-bonded dimers stack on top of each other with an inter-planar spacing of 3.44 Å. C-H⋯N hydrogen bonds link together stacks that run in approximately perpendicular directions. Each mol-ecule thus inter-acts with 12 adjacent mol-ecules, five of them approaching closer than the sum of the van der Waals radii for the relevant atoms. Optimization of the inter-stack contacts contributes to the non-planarity of the mol-ecule.
- 5 racconti umoristici: per una riflessione sull’umorismo nella letteratura portoghesePublication . Antunes, Luísa MarinhoQuando, nel 1946, al medico e intellettuale António de Almeida Garrett, è proposto di coordinare un’antologia del racconto umoristico portoghese, lui si pone la domanda su quali siano le caratteristiche più rappresentative dello humour nella Letteratura portoghese. La scelta di Camilo Castelo Branco (“o trocista implacável”), Eça de Queiroz (“o elegante caricaturista”), Ramalho Ortigão (“o da crítica graciosa”), Guerra Junqueiro (“o da universal piedade amassada com sarcasmo”) e Fialho de Almeida (“o estranho pintor satírico”), privilegia dimensioni che Almeida Garrett considera come identificative di un humour nazionale: il ricorso alla caricatura, la critica di tono satirico, il sarcasmo pietoso, l’umorismo impegnato e compromesso con la società, la gioia del giullare che ride felice anche delle tristezze. Queste caratteristiche sono infatti quelle che, per la loro iscrizione nella tradizione letteraria europea dell’Umorismo, restituiscono la dimensione di quegli scrittori come appartenenti alla grande letteratura europea e in dialogo con essa; e, considerate nel suo insieme e all’interno della letteratura portoghese, possono contribuire ad una riflessione sull’esistenza di una visione specifica dell’umorismo. When, in 1946, to the doctor and intellectual António de Almeida Garrett, is proposed to coordinate an anthology of Portuguese humorous stories, he raises the question of the most representative characteristics of humour in Portuguese literature. The choice of Camilo Castelo Branco ("o trocista implacável"), Eça de Queiroz ("o caricaturista elegante"), Ramalho Ortigão ("o da crítica graciosa"), Guerra Junqueiro ("o da universal piedade amassada com sarcasmo") and Fialho de Almeida ("o estranho pintor satírico"), favors dimensions that he considers that identify the national humor: the use of caricature, the criticism with a satyrical tone, the sarcasm with pity, the humor committed and compromised with society, the joy of the jester laughing happily, even of sadness. These features are in fact those which, for its inscription in the European literary tradition of humour give the dimension of these writers as part of the great European literature and in dialogue with it, and, taken as a whole and within the Portuguese literature, they can contribute to a reflection on the existence of a unique and national vision of humour.
- Above-ground biomass estimation for Quercus rotundifolia using vegetation indices derived from high spatial resolution satellite imagesPublication . Macedo, Fabrício L.; Sousa, Adélia M. O.; Gonçalves, Ana Cristina; Marques da Silva, José R.; Mesquita, Paulo A.; Rodrigues, Ricardo A. F.The estimation of vegetation parameters, such as above-ground biomass, with high accuracy using remote sensing data, represents a promising approach. The present study develops models to estimate and map above-ground biomass of Mediterranean Quercus rotundifolia stands using one QuickBird satellite image in pan-sharpened mode, with four multispectral bands (blue, green, red and near infrared) and a spatial resolution of 0.70 m. The satellite image was orthorectified, geometrically and radiometrically corrected. Object-oriented classi fication methods and multi-resolution segmentation were used to derive a vegetation mask per forest species. Data from forest inventory (24 plots) and vegetation indices (NDVI, EVI, SR and SAVI) derived from high spatial resolution satellite images were used for an area of 133 km2 , in southern Portugal. The statistical analysis included correlation, variance analysis and linear regression. The linear regression models fitted included the arithmetic mean and the median values of the vegetation indices per inventory plot as explanatory variables. The overall results of the fitted models show a trend of better performance for those with the median value of the vegetation index as the explanatory variable. The best fitted model (R2 = 75.3) was associated with the Simple Ratio (SR) median value as an explanatory variable. A Quercus rotundifolia above-ground biomass map was produced.
- Abscisic acid mimic-fluorine derivative 4 alleviates water deficit stress by regulating ABA-responsive genes, proline accumulation, CO2 assimilation, water use efficiency and better nutrient uptake in tomato plantsPublication . Jiménez-Arias, David; Morales-Sierra, Sarai; Suárez, Emma; Lozano-Juste, Jorge; Coego, Alberto; Estevez, Juan C.; Borges, Andrés A.; Rodriguez, Pedro L.Water deficit represents a serious limitation for agriculture and both genetic and chemical approaches are being used to cope with this stress and maintain plant yield. Next-generation agrochemicals that control stomatal aperture are promising for controlling water use efficiency. For example, chemical control of abscisic acid (ABA) signaling through ABA-receptor agonists is a powerful method to activate plant adaptation to water deficit. Such agonists are molecules able to bind and activate ABA receptors and, although their development has experienced significant advances in the last decade, few translational studies have been performed in crops. Here, we describe protection by the ABA mimic fluorine derivative 4 (AMF4) agonist of the vegetative growth in tomato plants subjected to water restriction. Photosynthesis in mock-treated plants is markedly impaired under water deficit conditions, whereas AMF4 treatment notably improves CO2 assimilation, the relative plant water content and growth. As expected for an antitranspirant molecule, AMF4 treatment diminishes stomatal conductance and transpiration in the first phase of the experiment; however, when photosynthesis declines in mock-treated plants as stress persists, higher photosynthetic and transpiration parameters are recorded in agonist-treated plants. Additionally, AMF4 increases proline levels over those achieved in mock treated plants in response to water deficit. Thus water deficit and AMF4 cooperate to upregulate P5CS1 through both ABA-independent and ABA dependent pathways, and therefore, higher proline levels are produced Finally, analysis of macronutrients reveals higher levels of Ca, K and Mg in AMF4-compared to mock-treated plants subjected to water deficit. Overall, these physiological analyses reveal a protective effect of AMF4 over photosynthesis under water deficit and enhanced water use efficiency after agonist treatment. In summary, AMF4 treatment is a promising approach for farmers to protect the vegetative growth of tomatoes under water deficit stress.
- Abscisic acid phytohormone estimation in tubers and shoots of Ipomoea batatas subjected to long drought stress using competitive immunological assayPublication . Gouveia, Carla S. S.; Ganança, José F. T.; Slaski, Jan J.; Lebot, Vincent; Carvalho, Miguel Â. A. Pinheiro deSweet potato (Ipomoea batatas L.), typically cultivated in temperate climates under low inputs, is one of the most important crops worldwide. Abscisic acid (ABA) is an important plant stress-induced phytohormone. Hitherto, few works analyzed the ABA function in sweet potato tissue growth. Very scarce information is available concerning the ABA role in sweet potato response to water scarcity conditions. Here, we show the ABA content var iation in shoots and tubers of eight sweet potato accessions subjected to drought stress. ABA was also related to other resistance traits, such as chlo rophyll content index (CCI), carbon isotopic discrimination (Δ13C), oxalic acid (OA) and water use efficiency (WUE), to assess stress response mecha nisms to water deficit between their organs. The most resilient drought stressed sweet potato plants accumulated ABA-shoot, and significantly decreased the ABA-tuber content. ABA signaling was related to Δ13C and CCI decrease and WUE increment, as an attempt to cope with water stress by partially closing the stomata. The partial closure of stomata could be in part due to the presence of OA-shoots, known to affect the intensity of the ABA-shoot signal in stomatal closure. Higher CCI content and minimal Δ13C-shoot differences indicated good carboxylation fractionation, with higher Δ13C-tuber content as an indicator of efficient tuber 13C fixation and growth. Our work demonstrated that ABA could be used in conjunction with the other traits studied for the assessment of sweet potato whole-plant responses to environmental stresses, and thus aid the selection of the best drought tolerant genotypes for breeding programs.
- Abundance and population structure of Plesionika narval (Fabricius, 1787) in the Northeastern AtlanticPublication . Sousa, R.; Pinho, M. R.; Delgado, J.; Pinto, A. R.; Biscoito, M.; Dellinger, T.; Henriques, P.Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL) ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.