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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Quantitative determination of quinone chromophore changes during ECF bleaching of kraft pulp

Zawadzki, Michael A. 08 1900 (has links)
No description available.
342

Les couches picturales stratifiées: analyse et modélisation de l'aspect visuel

Latour, Gaël 12 December 2007 (has links) (PDF)
Une peinture est un matériau complexe composé de plusieurs couches picturales. Ce travail de recherche poursuit un double but : comprendre et modéliser l'aspect visuel d'un tel milieu stratifié et développer des méthodes non destructives permettant d'identifier les différents constituants présents dans une œuvre d'art. L'équation de transfert radiatif, résolue par la méthode de la fonction auxiliaire, permet de modéliser l'aspect visuel des couches picturales stratifiées. Cette modélisation est validée par comparaison avec des spectres expérimentaux de réflexion diffuse. Expérimentalement, la reconnaissance des pigments et des colorants à partir d'un appareil déjà opérationnel au laboratoire a été étendue à celle des constituants d'un mélange de pigments. De plus, la tomographie optique cohérente (OCT), développée au cours de cette thèse, permet d'imager les pigments et d'obtenir une information spectrale permettant d'envisager une identification non destructive des composants de couches picturales stratifiées.
343

ALTERATIONS CHROMATIQUES DES PIGMENTS AU PLOMB DANS LES ŒUVRES DU PATRIMOINE -Etude expérimentale des altérations observée sur les peintures murales-

Aze, Sébastien 31 March 2005 (has links) (PDF)
Les pigments au plomb (minium, céruse), couramment employés en peinture depuis l'Antiquité, sont connus pour subir des transformations entraînant des décolorations de la couche picturale (noircissement, blanchissement, verdissement). Les conditions de stabilité des pigments sont étudiées par des essais de vieillissement artificiels de pigments bruts et d'éprouvettes peintes. Ceux-ci montrent la décomposition de l'hydrocérusite en présence de chaux ainsi que la transformation de Pb3O4 en plattnérite (b-PbO2) en milieu acide dilué. La caractérisation d'échantillons de minium prélevés sur un peinture murale expérimentale après 25 ans de vieillissement naturel révèle que le noircissement du minium est lié à la formation de plattnérite par un mécanisme possible de disproportionnation de Pb3O4 en milieu acide. Le<br />blanchissement est dû à la recristallisation du plomb divalent sous forme de cérusite (PbCO3) et d'anglésite (PbSO4), causée par l'absorption de polluants gazeux (CO2, SO2).
344

An investigation, using synchrotron radiation and other techniques, of the composition of San rock art paints and excavated pigments from Maqonqu shelter, and comparative paint data from three other sites in KwaZulu-Natal, South Africa.

Escott, Boyd John. January 2011 (has links)
This study aimed to: 1) characterise the individual San parietal art rock art paint colours; 2) relate paint compositions to erosion susceptibility; 3) determine if paint pigments can be related to pigment samples excavated from a Shelter deposit, and/or a variety of field samples; and 4) determine if paint samples from geographically distinct sites can be distinguished on their composition. A combination of mineralogical (X-ray diffraction (XRD), synchrotron micro-XRD (μ-XRD)) and chemical (energy dispersive X-ray micro-analysis (EDX), X-ray fluorescence spectrometry (XRF), and synchrotron micro-XRF (μ-XRF)) analytical techniques were used. Maqonqo Shelter (MQ), 35 km south-east of Dundee, KwaZulu-Natal, South Africa, was the primary study site chosen as it contained both a large number of paintings, as well as a large deposit. Thirty paint (of various colours) and 3 blank wall samples were collected using Silver Mylar tape and analysed using a combination of EDX, μ-XRD and μ-XRF techniques. Sixty two large (> 2.5 g) ‘ochre’ pieces were selected from the upper three layers of the deposit and analysed using XRD, XRF and EDX. A further 63 small pieces (< 2.5 g) were analysed using μ-XRD and μ-XRF techniques. To compare the MQ paint samples with potential source materials, three distinct sample sets were collected. The first included samples of the Shelter wall and surface rocks located near the painted panel (analysed by XRD, XRF and EDX). A second sample set of 17 samples was collected from the surrounding landscape (± 3 km radius of MQ; analysed by XRD and XRF). Their selection was based on ease of accessibility, degree of pulverulence, and perceived Fe content i.e., red and/or yellow colouration. No white sources were found. A third set of 11 samples (obtained from six sites, analysed using XRD and XRF) was collected within ± 50 km distance of the Shelter. Their selection was based on old mining survey reports that detailed the location of Fe ore outcrops. Paint samples from three additional shelters i.e., Fergies Cave (FC), Giants Castle Game Reserve, central Drakensberg; Sheltered Vale (SV), Mount Currie District, south-western KwaZulu-Natal; and Twagwa Shelter (TW), Izingolweni District, southern KwaZulu-Natal, were collected to compare paint composition over distance. Site selection was determined according to the following criteria: 1) the shelters had to reside a significant distance away from the primary site so as to minimise any possible interaction that might have existed between the authors of the respective artworks (each site is at least 100 km distant from the other); 2) each had to be located upon a distinct geological formation so that external influences from different regions, and their possible affects on the paint samples, could be noted; and 3) the climatic regimes of each of the shelters should be relatively distinct. Fifteen paint and nine blank wall samples were collected from the three shelters (three each of red, white and blank samples; analysed using EDX, μ-XRD and μ-XRF), with the exception that no white samples were collected from FC. In total, 673 EDX, 212 μ-XRD, 378 μ-XRF, 98 XRD, 98 XRF and 6 ICP-MS traces were produced and analysed. Due to the extremely heterogeneous nature of the paint samples at the microii scale, the more generalised EDX reduced window scans were used as the basis of the paint samples’ characterisation, with the data obtained from the more precise μ-XRD and μ-XRF techniques providing additional supportive information. Irrespective of colour, almost all of the MQ paint samples had elevated Ca contents that tended to increase in the order of black < orange £ red and yellow < pink < white. The predominant Ca-based mineral was gypsum, although Ca-oxalates, whewellite and weddellite, were also present. The blank samples collected from MQ also had high gypsum content, but no Ca-oxalate. It is thus proposed that the Ca-oxalates formed after the painting event and were derived from the original paint constituents. The white pigments consisted of gypsum (dominant), anhydrite, bassanite and whewellite, or a combination thereof. Whewellite increased within increasing paint depth, while gypsum showed the reverse trend. This indicates that, whilst both gypsum and whewellite were originally present within the original paint pigment, additional gypsum has been added via secondary evaporite deposition. Although initially considered to be sourced along with the gypsum, another potential whewellite source is organic additives. The most likely source for the white pigments would be precipitates found on sandstone walls of shelters near MQ. Of more immediate importance, however, is that the pigments, being gypsum based, are water-soluble and thus susceptible to erosion. Most of the orange paints had an elevated Al content and contained gibbsite, suggesting bauxitic material associated with locally sourced dolerite within the Ecca Series within KwaZulu-Natal (as evidenced by their respective Ti levels). Two samples were so similar that it is likely that the same pigment was utilised in the creation of both images. Two samples did not contain high Al contents, however, indicating that they were probably sourced from the soft, ochreous material found within local Fe nodules. A consistent combination of goethite and haematite, together with a low Al and elevated Ti content, indicate that the yellow and red samples were probably sourced from Fe nodules found locally, the red samples differing from the yellow pigments primarily in their higher haematite content. A low Si and relatively low Fe content discounts red sands/clays and Fe-ores as sources of the red pigments. The red samples were ‘thinner’ than the other samples with quartz contents comparable to those of the blank samples. The thin nature of the red paints, the erratic distribution of whewellite upon the paint surfaces, the dominance of gypsum and, to a certain extent quartz, all strongly suggest that the red paints are at least partly absorbed into the surface of the Shelter wall. This, together with the strong staining ability of haematite, is probably the most important reason that the red pigments have outlasted images painted in other colours. It may also account for the high degree of variability found within the red paint dataset, though age differences between the sampled images could also be a contributing factor. The single dark red paint sample, except for an elevated Mn content, was very similar in many ways to the red paint samples analysed. The only readily available pigment source identified that had both low Al and high Fe and Mn contents, was plinthite. The pink samples represented the ‘middleiii ground’ between the red and white paints, suggesting that this colour was the result of a blending of the two. The black paint sample had the highest recorded Fe content of the entire paint dataset. A high Mn and relatively low Al content suggest that a soft inner core of an Fe nodule was used in its manufacture. The presence of maghemite and a dark colouration strongly suggest that the manufacture also involved calcination. The initial distinction between the paint and excavated samples was that the former all exhibited elevated Ca and S values due to the deposition of secondary evaporite minerals. Even when taking these additional deposits into account, however, the two datasets still remained distinct indicating that the excavated materials sampled were not utilised in the manufacture of the MQ paints. A potential exception concerned the orange paint samples, which were similar in composition to both doleritic samples from deeper excavated layers and the local (weathered doleritic samples) and distant (bauxite samples) field samples. Whilst weathered dolerite/bauxitic material was clearly the source of the orange pigments, a more detailed investigation is needed to find a precise location. No other relationships between the paint pigments and the excavated pigments and field samples were established. A comparison of the blank samples from all four study sites showed that the techniques used could distinguish between different sites despite sampling the smallest and, relatively speaking, poorest quality samples. The FC blank samples had elevated C and Ca contents (associated with Caoxalates). The conditions within this Shelter favour the formation of weddellite and whewellite, the former not typically found at the other three sites. In addition, low K, Si and Al contents (often associated with sandstone matrix minerals) indicate that the surface of the relatively dense, compact Cave sandstone is more resistant to physical erosion compared to the other sites, and/or FC shelter experiences a high amount of secondary deposition, with the result that a majority of the samples are composed of evaporite minerals. The SV samples were composed primarily of the evaporite-type minerals, with only minor sandstone ‘contamination’ indicated by quartz and kaolinite. The quartz content, whilst not always high, was present in most of the samples analysed, possibly indicating a greater amount of more uniform surface erosion (relative to the other sites). The TW blank samples were distinct from the other shelters’ as they contained no Ca-based minerals but did contain the very rare mineral schlossmacherite. A comparison of the paint colours also revealed differences between the different shelters. Whilst the white samples from SV and MQ are dominated by whewellite and gypsum (minerals probably present within the pigments when they were applied), the presence of quartz, sanidine and apatite in the SV samples indicated a degree of shelter wall ‘contamination’, with anhydrite, bassanite and glushinskite suggesting climatic variations that favoured various evaporite depositional regimes. The TW white paint contained minimal secondary deposited minerals common in the other shelters. The one mineral that is dominant within the TW samples is minamiite. As this mineral was not identified in any of the blank samples, it is likely that this mineral originates from the original pigment source. The TW white paints also contained 10 to 40 times more Zn than those recorded for any of the other paint samples. This was possibly present within the structure of greigite. The red SV samples could be distinguished from MQ red samples by the presence of wall ‘contaminants’ in a manner similar to that described for the white samples. The TW samples indicate a change in pigment source and/or manner of paint manufacturing technique, for these red samples contained minamiite. This mineral is white and thus its selection could not have been based on colour but rather it must represent a paint additive. With the exception of only one sample from TW, no goethite was found within any of the red samples collected from the three additional sites indicating a different haematite source to that of MQ. An interesting facet of this study, although not directly addressed, concerns what the results do not show with respect to the compositional nature of the pigments analysed. Most texts available today list a number of pigment sources stated to have been utilised in the manufacture of the San parietal rock art. This study has shown that very few of these potential sources were utilised within the four shelters investigated. In addition, this study has also highlighted the presence of minerals about which little is known, yet which appear to be commonly associated with parietal rock art. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
345

Synthesis and characterization of novel black pigments / Naujų juodųjų pigmentų sintezė ir tyrimas

Gatelytė, Aurelija 02 April 2012 (has links)
For this doctoral dissertation there were synthesized and observed the black pigments which are important in both – in art and industry. It was the first time when using the sol-gel method in our laboratory were synthesized YFeO3, Y3Fe5O12, CoFe2O4, NiFe2O4, ZnFe2O4 nanocompounds, which latter were fitted for the black pigmentation of the ceramic glazes. / Buvo sudaryti modeliniai juodieji pigmentai iš C suodžių ir K2CO3, Ca3(PO4)2, CaCO3 bei Mg3(PO4)2.Vandeniniu zolių-gelių metodu buvo susintetinti įvairūs metalų vienfaziai nanoferatai YFeO3, Y3Fe5O12, CoFe2O4, NiFe2O4, ZnFe2O4, kurie pirmą kartą panaudoti juodaisiais keraminiais pigmentais.
346

Naujų juodųjų pigmentų sintezė ir tyrimas / Synthesis and characterization of novel black pigments

Gatelytė, Aurelija 02 April 2012 (has links)
Buvo sudaryti modeliniai juodieji pigmentai iš C suodžių ir K2CO3, Ca3(PO4)2, CaCO3 bei Mg3(PO4)2.Vandeniniu zolių-gelių metodu buvo susintetinti įvairūs metalų vienfaziai nanoferatai YFeO3, Y3Fe5O12, CoFe2O4, NiFe2O4, ZnFe2O4, kurie pirmą kartą panaudoti juodaisiais keraminiais pigmentais. / For this doctoral dissertation there were synthesized and observed the black pigments which are important in both – in art and industry. It was the first time when using the sol-gel method in our laboratory were synthesized YFeO3, Y3Fe5O12, CoFe2O4, NiFe2O4, ZnFe2O4 nanocompounds, which latter were fitted for the black pigmentation of the ceramic glazes.
347

Relação entre estresse de radiação ultravioleta-b e óxido nítrico em plantas de eucalipto

Corniani, Natália [UNESP] 22 July 2010 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:23:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-07-22Bitstream added on 2014-06-13T20:10:55Z : No. of bitstreams: 1 corniani_n_me_botfca.pdf: 1146521 bytes, checksum: fa6a3da1e11828289d5c9cb1e7208258 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As espécies do gênero Eucalyptus apresentam notável capacidade de extração de água e nutrientes, assimilação fotossintética e crescimento, permitindo seu cultivo em ambientes considerados impróprios para muitas outras espécies. Além dos fatores ambientais atuando adversamente no desempenho das plantas, atualmente estas estão sujeitas aos efeitos das mudanças ambientais globais causadas pelas atividades antrópicas, tais como o aumento na incidência da radiação ultravioleta-B (RUV-B) em conseqüência da destruição da camada de ozônio. Estudos recentes têm mostrado que a RUV-B promove aumento no nível de espécies reativas de oxigênio (ERO), ocasionando estresse oxidativo nas plantas. Entretanto, as plantas apresentam um sistema de defesa contra o estresse oxidativo, constituído de enzimas antioxidantes, tais como superóxido dismutase (SOD, EC 1.15.1.1) e peroxidase (POD, EC 1.11.1.7), além de outros compostos, como antocianinas, carotenóides e compostos fenólicos, que impedem a formação de ERO ou eliminam as já existentes. Há algum tempo, tem sido verificada em plantas a presença de óxido nítrico (NO), radical livre endógeno que possui a capacidade de controlar o nível e a toxicidade das ERO. Portanto, o objetivo deste trabalho foi investigar o possível efeito citoprotetor do NO em plantas de eucalipto (Eucalyptus urograndis) expostas à RUV-B. Assim, foi realizado um primeiro experimento no qual plantas de eucalipto foram expostas à RUV-B em baixa (controle) e elevada incidência, com o intuito de verificar se a radiação promove estresse oxidativo nesta espécie. Foram realizadas coletas de lâminas foliares aos cinco, dez e quinze dias após o início da exposição à RUV-B para posterior determinação do nível de peroxidação lipídica. A exposição por 15 dias à RUV-B... / The species of the genus Eucalyptus present notable capacity to extract water and nutrients, photosynthetic assimilation and growth, allowing cultivation in ambient considered inappropriate for many other species. Besides the environmental factors acting adversely in the performance of the plants, nowadays they are subject to the effects of the global environmental changes caused by human activities, such as the increase in the incidence of the ultraviolet-B radiation (UV-B) in consequence of the ozone layer destruction. Recent studies show that UV- B radiation promotes increase in the level of reactive oxygen species (ROS), causing oxidative stress in plants. However, plants have a defence system against oxidative stress, constituted of antioxidant enzymes, such as, superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), and others compounds, such as anthocyanins, carotenoids and phenolic compounds, that avoid ROS formation or eliminate the already existent. There has been long, it was noticed the presence of nitric oxide (NO) in plants, endogenous free radical able to control the ROS level and toxicity. Therefore, the aim of this work was to investigate the possible citoprotector effect of the NO in eucalyptus (Eucalyptus urograndis) plants subjected to UV-B radiation. So, a first experiment was setup in which plants of eucalyptus were subjected to radiation in low (control) and high incidence of UV-B, to verify if UV-B radiation promotes oxidative stress in this specie. Leaves were collected at five, ten and fifteen days after the beginning of exposure to UV-B for subsequent evaluation of the level of lipid peroxidation. Exposure for 15 days to RUV-B increased the lipoperoxide content in the eucalyptus... (Complete abstract click electronic access below)
348

S?ntese de pigmento cer?mico ferrita de cobalto utilizando planejamento experimental

Medeiros, Patricia Neves de 01 March 2013 (has links)
Made available in DSpace on 2014-12-17T14:07:11Z (GMT). No. of bitstreams: 1 PatriciaNM_DISSERT.pdf: 6134806 bytes, checksum: 48ee86ee041e8aea24a2f38fd4fbf43a (MD5) Previous issue date: 2013-03-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Synthetic inorganic pigments are the most widely used in ceramic applications because they have excellent chemical and thermal stability and also, in general, a lower toxicity to man and to the environment. In the present work, the ceramic black pigment CoFe2O4 was synthesized by the polymerization Complex method (MPC) in order to form a material with good chemical homogeneity. Aiming to optimize the process of getting the pigment through the MPC was used a fractional factorial design 2(5-2), with resolution III. The factors studied in mathematical models were: citric acid concentration, the pyrolysis time, temperature, time and rate of calcination. The response surfaces using the software statistica 7.0. The powders were characterized by thermal analysis (TG/DSC), x-ray diffraction (XRD), scanning electron microscopy (SEM) and spectroscopy in the UV-visible. Based on the results, there was the formation of phase cobalt ferrite (CoFe2O4) with spinel structure. The color of the pigments obtained showed dark shades, from black to gray. The model chosen was appropriate since proved to be adjusted and predictive. Planning also showed that all factors were significant, with a confidence level of 95% / Os pigmentos inorg?nicos sint?ticos s?o os mais utilizados em aplica??es cer?micas por apresentarem uma excelente estabilidade qu?mica e t?rmica e tamb?m, em geral, uma menor toxicidade para o homem e para o meio ambiente. No presente trabalho, o pigmento cer?mico preto CoFe2O4 foi sintetizado pelo M?todo de Polimeriza??o de Complexos (MPC) visando a forma??o de um material com boa homogeneidade qu?mica. Com o objetivo de otimizar o processo de obten??o do pigmento atrav?s do MPC foi utilizado um planejamento fatorial fracionado 2(5-2), com resolu??o III. Os fatores estudados na modelagem matem?tica foram: concentra??o de ?cido c?trico, tempo de pir?lise, temperatura, tempo e taxa de calcina??o. As superf?cies de resposta utilizando o programa statistica 7.0. Os p?s obtidos foram caracterizados atrav?s de an?lises t?rmicas (TG/DSC), difra??o de raios-x (DRX), microscopia eletr?nica de varredura (MEV) e espectroscopia na regi?o do UV-vis?vel. Com base nos resultados, foi verificada a forma??o da fase ferrita de cobalto (CoFe2O4) com estrutura espin?lio. A cor dos pigmentos obtidos apresentou tonalidades escuras, do preto ao cinza. O modelo escolhido foi adequado, visto que mostrou-se ajustado e preditivo. O planejamento tamb?m mostrou que todos os fatores foram significativos, com n?vel de confian?a em 95%
349

Avaliação de compostos bioativos em frutos nativos do Rio Grande do Sul

Pereira, Marina Couto January 2011 (has links)
O Rio Grande do Sul se destaca por sua riqueza florística, entretanto, muitas espécies frutíferas permanecem desconhecidas, embora possuam potencial para se tornarem competitivas com as espécies já tradicionais. Neste sentido, este trabalho visa aprofundar a caracterização de alguns frutos nativos da região, estimulando a exploração desta biodiversidade, esclarecendo a potencialidade dos produtos e sua utilização em prol dos benefícios a saúde e o avanço da economia local e nacional. Para isso, foi realizada uma caracterização bromatológica e fitoquímica, como também foi verificado o potencial antioxidante de frutos nativos tais como: araticum (Rollinia sylvatica A. St.-Hil.), araçá (Psidium cattleyanum Sabine), butiá (Butia capitata Mart. (Becc.)), gabiroba (Campomanesia xanthocarpa O. Berg.), uvaia (Eugenia pyriformis Cambes.) e tuna (Cereus hildmannianus K. Schum.). A partir dos resultados, pode-se verificar que entre os frutos da família Myrtaceae, a guabiroba destacou-se por apresentar maior quantidade de compostos fenólicos (1495,27 mg/100g), carotenóides (54,35 μg/g), e vitamina C (5,44 mg/ g) como também um excelente potencial antioxidante (90,26 M eq. trolox/g de fruto fresco e 906,63 g de fruto fresco/g DPPH), indicando ser um fruto bastante promissor tanto para consumo in natura quanto para utilização tecnológica, visto que também obteve melhor relação SST/ATT (45,12). Entretanto, esse mesmo fruto se sobressaiu com os teores mais elevados de Al (31,27 μg/g) e Cr (1,80 μg/g), juntamente com a uvaia (1,56 μg/g), que demonstrou quantidades superiores de Fe (21,27 μg/g) e Zn (60,48 μg/g). A uvaia também se destacou pelo elevado teor de carotenóides (50,09 μg/g). O araçá, apesar de apresentar teores de compostos fenólicos e atividade antioxidantes inferiores à guabiroba, ainda assim apresentou-se superior a muitas frutas tradicionalmente consumidas. Quanto aos minerais analisados, o araçá amarelo se destacou pelo elevado teor de Na (828,78 μg/g) e o vermelho de Co (3,27 μg/g). Em relação ao outro grupo de frutos estudado, de famílias botânicas variadas, o butiá e a tuna apresentaram capacidade antioxidante superior à uvaia e à muitas espécies frutíferas tradicionalmente consumidas. O butiá também se destacou com teor mais elevado em carotenóides (39,6 μg/g) e nos minerais Cd (0,06 μg/g) e Ni (4,99 μg/g). A tuna apresentou maior conteúdo de compostos fenólicos totais (1337,28 mg/100g) e predomínio de Ba (7,97 μg/g), Bi (6,36 μg/g), Ga (6,02 μg/g), Mg (1215,54 μg/g ) e Mn (207,90 μg/g). O araticum se sobressaiu quanto a concentração de vitamina C (0,32 mg/g) e no resultado para SST/ATT (41,92), mostrando-se adequado tanto para o consumo in natura como para o processamento. Para este mesmo fruto ainda foi observada quantidade de Cu (80,38 μg/g) acima do recomendado, assim como também teve destaque com maiores concentrações de Pb (0,10 μg/g), Sr (28,95 μg/g), Ca (2579,50 μg/g) e K (11522,03 μg/g). / The Rio Grande do Sul State (Brazil) stands out for its richness flora, however, many fruit species remain unknown, although they have the potential to become competitive with the traditional species. Thus, this work aimed to deepen the characterization of some native fruits of the region, encouraging the exploitation of our biodiversity, preventing biopiracy, clarifying the potential of our products and their use in support of health benefits and advancement of the local and national economy. For this, we performed a phisicochemical and phytochemical characterization, and also was determined the potential of antioxidant custard apple (araticum) (Rollinia sylvatica A. St .- Hil.), Guava (araçá) (Psidium cattleyanum Sabine) coco palm (butiá) (Butia capitata Mart. (becc.)), gabiroba (Campomanesia xanthocarpa O. Berg.), uvaia (Eugenia pyriformis Cambes.) and tuna cactus (tuna) (Cereus hildmannianus K. Schum.). From the results, one can see that among the fruits of the Myrtaceae, the guabiroba stood out due to its greater quantity of phenolic compounds (1495.27 mg/100g), carotenoids (54.35 μg/g), and vitamin C (5.44 mg/g), as well as, an excellent antioxidant potential (90.26 M trolox/g and 906.63 g/g DPPH) could be a promising fruit for both fresh consumption and for use technology, since they also obtained better TSS/TTA ratio (45.12). However, the guabiroba showed the highest levels of Al (31.27 μg/g) and Cr (1.80 μg/g), together with uvaia (1.56 mg/g), which showed higher amounts Fe (21.27 μg/g) and Zn (60.48 μg/g). The uvaia also stood out for presenting a relevant carotenoid content (50.09 μg/g). Yellow guava, although showing a lower phenolic compound content and antioxidant activity then the guabiroba, nevertheless showed much higher values than many traditionally consumed fruit. Regarding minerals, the yellow guava stood out high concentrations of Na (828.78 μg/g) and the red guava Co (3.27 μg/g). The coco palm (25.96 trolox μM/g and 3847.54 g/g DPPH) and tuna cactus (19.61 trolox μM/g 3249.77 g/g DPPH) showed higher antioxidant capacity than many fruit species traditionally consumed. In the other group of fruits studied, in various plant families, the coco palm fruit stood out due to its elevate carotenoid content (39.6 μg/g) and minerals Cd (0.06 μg/g) and Ni (4.99 μg/g). The tuna cactus fruit showed the highest total phenolic compound content (1337.28 mg/100 g) and predominance of Ba (7.97 μg/g), Bi (6.36 μg/g), Ga (6.02 μg/g) Mg (1215.54 μg/g) and Mn (207.90 μg/g). Although the custard apple showed the highest vitamin C content (0.32 mg/g) showed the best result for the TSS/TTA ratio (41.92), and was thus adequate for both in natura consumption and for processing. This fruit was also observed amounts of Cu (80.38 μg/g) above the recommended, as was also stood out for its high concentrations of Pb (0.10 μg/g), Sr (28.95 μg/g), Ca (2579.50 μg/g) and K (11,522.03 μg/g).
350

Perfil de antocianinas e potencial antioxidante de vinhos tintos brasileiros / Anthocyanins profile and scavenging properties of brazilian red wines

Dullius, Mariana de Vasconcellos January 2012 (has links)
A atividade antioxidante (AOX) de vinhos é decorrente, dentre outros fatores, da presença de substâncias fenólicas, como as antocianinas que, além de contribuírem para a formação da cor, devido a sua capacidade redutora, são capazes de neutralizar moléculas de radicais-livres. No presente trabalho, 92 amostras de vinhos tintos da safra 2008/2009, provenientes de diversas regiões do país, agrupadas de acordo com a sua similaridade (UF e fisiografia), foram analisados quanto à cor, através de parâmetros de luz, saturação e tonalidade; à concentração de antocianinas totais (por espectrofotometria diferencial e por CLAE); à caracterização dos pigmentos (por CLAE); à concentração de polifenóis totais (IPT) (pelo método de Folin Ciocalteau’s); e à atividade antioxidante (por DPPH+), sendo que as duas últimas características foram avaliadas sob a forma de evolução temporal. Os resultados mostram que, em relação ao perfil evolutivo, pelo menos um dos grupos difere (p<0,05) nos tempos. A região Vale do Rio São Francisco (VSF) exibiu, tanto os mais elevados valores de IPT em todos os tempos de análise [(tzero=4.516; t25=3.516; t35=2.475; t45=2.027; t55=1.598) mg.L-1 GAE], quanto a mais alta AOX, nos quatro primeiros dos cinco momentos avaliados. A região Oeste do Paraná (OPR) apresentou os mais baixos resultados para ambos os parâmetros considerados em todos os tempos medidos, sendo que os valores de IPT corresponderam a 47, 52, 54, 58 e 63% e os valores de AOX a 49, 55, 57, 61 e 79% dos valores encontrados para VSF. No decorrer das 55 semanas avaliadas, as diferenças entre os grupos tende a diminuir. Em relação aos pigmentos, 12 padrões comerciais permitiram comparar os vinhos no que diz respeito as presença e a quantificação destes compostos. À exceção de dois, todos os vinhos analisados por CLAE confirmaram a malvidina-3-monoglicosídeo (Mv-3G), como o composto antociânico predominante. O Vale dos Vinhedos (Vvi) apresentou os maiores conteúdos, tanto do pigmento majoritário da uva (Mv-3G – 38,66 μ.L-1), quanto da cianidina-3-monoglicosídeo (Cn- 3G – 0,914 μ.L-1), composto antociânico mais relatado em alimentos. Correlações fortes e muito fortes foram observadas entre IPT e AOX e fortes entre antocianinas totais (expressas em Mv-3G por espectrofotometria diferencial) e Mv-3G (quantificada por CLAE). ANOVA mostrou que, em CLAE, não houve diferenças (p<0,1) entre as regiões, indicando que variações internas nos grupos, sobressaíram-se às evidenciadas pelas regiões, não sendo possível caracterizá-las conforme o tipo nem a concentração de antocianinas. / The antioxidant capacity (AOX) of wines is due, among other factors the phenolic substances, such as anthocyanins that, beyond to color contribution, present scavenging properties, having effect on radical oxygen species (ROS). In this study, 92 samples of 2008/2009 vintage Brazilian red wines, from dissimilar production areas, were grouped according to similarities (Federal State and physiographic attributes) and analyzed in terms of color, through light, saturation and hue parameters; in terms of total anthocyanin concentration (by pH-differential spectrophotometric methods and high performance liquid chromatography (HPLC)); in terms of pigment characterization (HPLC); in terms of total polyphenols concentration (IPT) (Folin Ciocalteau’s method); and in terms of its scavenging properties (DPPH+), being the last two attributes analyzed over time evolution profile. The results showed that for the evolution profile, at least one of the groups differed (p<0,05) in the evaluated times. The “Vale do Rio São Francisco” (VSF) region exhibited not only the most elevated values for IPT in all analyzed sampling [(tzero=4,516; t25=3,516; t35=2,475; t45=2,027; t55=1,598) mg.L-1 GAE], as the most AOX in the first four from the five evaluated moments. The “Oeste do Paraná” (OPR) presented the lowest results for both IPT and AOX parameters, in all measuring times, and the IPT values corresponded to 47, 52, 54, 58 e 63%, while the AOX values to 49, 55, 57, 61 e 79% from values found for VSF. Over the 55 weeks, the differences among groups tended to diminish. Considering the pigments, 12 commercial standards allowed to compare wines based on presence and concentration of these compounds. Except for two samples, all the HPLC-analyzed wines confirmed the malvidin-3-monoglucoside, as the anthocyanin most abounding in wines. The VVi exhibited the highest levels, even for the grape major pigment (Mv- 3G – 38.66 μ.L-1), as for cianidin-3-monoglucoside (Cn-3G – 0.914 μ.L-1), the most reported anthocyanin in food. Strong and very strong correlations were found among IPT and AOX, while total anthocyanins (in Mv-3G base, by pH-differential analysis) and Mv-3G concentration (by HPLC) exhibited strong linear associations. ANOVA showed that, in terms of chromatographic analysis, no differences (p<0,1) among regions were found, indicating that inside-groups variations were high enough to not allow the characterization according to qualitative and quantitative anthocyanin profile.

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