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| Registros recuperados: 15 | |
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| Le Gac, Pierre-yves; Le Saux, V.; Paris, M; Marco, Y.. |
| Polymers are widely used in marine environments due to their excellent properties and good weathering resistance. Despite this extensive use, their long term behaviour in such an aggressive environment is still not well known. To assess the polymer durability within reasonable durations, it is essential to perform accelerated ageing tests to accelerate the degradation kinetics but without any modification of the degradation process. This study therefore proposes and validates accelerated ageing tests to study marine ageing of a silica-filled chloroprene rubber (CR) used for offshore applications. Several accelerated ageing protocols are investigated for temperatures ranging from 20 to 80 degrees C in renewed natural seawater. The ageing consequences are... |
| Tipo: Text |
Palavras-chave: Chloroprene rubber; Degradation; Sea water; Silica; Accelerated ageing; Natural ageing. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00073/18429/20232.pdf |
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| Dekov, V. M.; Lalonde, Stefan; Kamenov, G. D.; Bayon, Germain; Shanks, W. C., Iii; Fortin, D.; Fouquet, Yves; Moscati, R. J.. |
| An inactive vent field comprised of dead chimneys was discovered on the ultrafast East Pacific Rise (EPR) at 18°S during the research campaign NAUDUR with the R/V Le Nadir in December 1993. One of these chimneys was sampled, studied and found to be largely composed of silica-mineralized bacterial-like filaments. The filaments are inferred to be the result of microbial activity leading to silica (± Fe-oxyhydroxide) precipitation. The chimney grew from the most external layer (precipitated 226 ± 4 yr. B.P.) towards the central chimney conduit. Hydrothermal activity ceased 154 ± 13 yr. B.P. and the chimney conduit was completely sealed. Mixing between an end-member hydrothermal fluid and seawater explains the Sr–Nd isotopic composition of the chimney.... |
| Tipo: Text |
Palavras-chave: Chimney; C-O-Si-Sr-Nd-Pb-Th-U isotopes; Hydrothermal; Seafloor; Silica. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00280/39143/37698.pdf |
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| Neubeck, Anna; Hemmingsson, Christoffer; Boosman, Arjen; Rouxel, Olivier; Bohlin, Madeleine. |
| The dramatic decline in aqueous Ni concentrations in the Archean oceans during the Great Oxygenation Event is evident in declining solid phase Ni concentrations in Banded Iron Formations (BIFs) at the time. Several experiments have been performed to identify the main removal mechanisms of Ni from seawater into BIFs, whereby adsorption of Ni onto ferrihydrites has shown to be an efficient process. Ni isotopic measurements have shown limited isotopic fraction during this process, however, most experiments have been conducted in simple solutions containing varying proportions of dissolved Fe and Ni as NO3 salts, as opposed to Cl salts which are dominant in seawater. Further, Archean oceans were, before the advent of siliceous eukaryotes, likely saturated with... |
| Tipo: Text |
Palavras-chave: Stable Ni isotopes; Ferrihydrite precipitation; Co-precipitation experiment; Banded; Iron Formation; Silica. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00661/77275/78710.pdf |
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| Romero, O. E.; Kim, J. -h.; Barcena, M. A.; Hall, I. R.; Zahn, R.; Schneider, R.. |
| The hydrography of the Indian-Atlantic Ocean gateway has been connected to high-latitude climate dynamics by oceanic and atmospheric teleconnections on orbital and suborbital timescales. A wealth of sedimentary records aiming at reconstructing the late Pleistocene paleoceanography around the southern African continent has been devoted to understanding these linkages. Most of the records are, however, clustered close to the southern South African tip, with comparatively less attention devoted to areas under the direct influence of frontal zones of the Southern Ocean/South Atlantic. Here we present data of the composition and concentration of the diatom assemblage together with bulk biogenic content and the alkenone-based sea surface temperature (SST)... |
| Tipo: Text |
Palavras-chave: Agulhas; SST; Diatoms; Fronts; Silica; Southern Ocean. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00294/40555/39440.pdf |
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| Pedrazzi,Vinícius; Del Ciampo,José Orestes; do Nascimento,Cássio; Issa,João Paulo Mardegan. |
| The aim of this study was to evaluate some biological characteristics and toxicity of basic formulations of dentifrices containing such substances, and to compare them with two existing products in market which also contains silic in their formulations. In this way, it was evaluated some biological parameters: weight of the animals, oral toxicity, hematological parameters, urinary analysis, and histological evaluation. The thrombocytes were also statistically at normal levels. The glutamate-pyruvate transaminase (TGP) showed normal aspect in 5 of the tested groups, as in control. Meanwhile, the oxalacetic transaminase (AST) in one group had a small increase in the control group. Regarding urine, in exception the rats of one group, the rats of the 4 other... |
| Tipo: Journal article |
Palavras-chave: Silica; Dentifrices; Histology; Wistar rats. |
| Ano: 2009 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-95022009000100028 |
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| Edris, Abass Edris Alsaid. |
| Pozzolana is a materials that content Reactive Silica with Alumina which defines as Siliceous materials, also include ferroginous materials. In generally, this study aimed to estimate Alternative building materials ( pozzolanic materials ) and create new cementic materials such as Lime-Pozzolana Cement and Ordinary Portland-Pozzolana Cement . The results shows that there is no good and sufficient pozzolanic materials as Obsidian , Scoria, Diatomaceous Earth and Volcanic Ash , but some types of burnt clays and Rhyolite in addition to bricks Reject and miskeet Ash was shown . This study is subjected in Arbaat Delta clay , salloum Delta clay , Rhyolite Rocks , bricks Reject and miskeet Ask as Natural and artificial pozzolanic materials. The identification of... |
| Tipo: Theses and Dissertations |
Palavras-chave: Silica. |
| Ano: 2012 |
URL: http://hdl.handle.net/1834/5073 |
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| Bayer,C.; Martin-Neto,L.; Saab,S. C.; Mielniczuk,J.. |
| A concentração de radicais livres semiquinona (CRLS), determinada por ressonância paramagnética eletrônica (EPR), é considerada um índice do grau de humificação, sendo uma importante determinação em estudos qualitativos da matéria orgânica do solo. Neste trabalho, avaliou-se a interferência da fração mineral na quantificação da CRLS em agregados organominerais 20-53, 2-20 e < 2 ∝m de Podzólico Vermelho-Amarelo, Podzólico Vermelho-Escuro e Latossolo Roxo. A CRLS foi determinada pela área do sinal, estimada pela aproximação intensidade do sinal (I, em cm), multiplicada pela sua largura de linha ao quadrado (∆H², em Gauss). Os parâmetros espectrais I e ∆H foram obtidos em espectros de EPR com e sem interferência da fração mineral. No Podzólico... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Radical livre semiquinona; Ferro; Silica. |
| Ano: 2000 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832000000100002 |
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| Carvalho,Carolina Rodrigues Victor de; Mapeli,Ana Maria; Oliveira,Andreia Barroncas de. |
| Abstract Passiflora cincinnata is a species of wild passion fruit whose fruit has potential for use by the food industry. In this context, an anatomical study of the pericarp may help in understanding the changes which occur during the postharvest period. The objective of this work was to anatomically characterize the P. cincinnata pericarp, focusing on the structural changes which occur during refrigerated storage. The selected fruits were kept in net-like packaging at 5°C and evaluated every 15 days for a period of 90 days. Pericarp samples were hand cut on these dates for structural description and to detect starch, phenolic compounds, alkaloids, polysaccharides, proteins, lipids and lignin through histochemical tests. Other samples were analyzed by... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Calcium oxalate crystals; Wild passion fruit; Postharvest; Histochemical tests; Silica. |
| Ano: 2021 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-29452021000200202 |
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| MONTEIRO,WESLEY F.; MIRANDA,GABRIELA M.; SOARES,RAFAEL R.; SANTOS,CLÁUDIA A.B. DOS; HOFFMANN,MAURÍCIO S.; CARONE,CARLOS L.P.; LIMA,VIVIANE DE; SOUZA,MILTON F. DE; CAMPANI,ADRIANO D.; EINLOFT,SANDRA M.O.; LIMA,JEANE E. DE; LIGABUE,ROSANE A.. |
| Abstract: Waterborne polyurethanes (WPUs) are interesting materials for coatings when compared to solvent-based polyurethanes, once that reducing the concentration of volatile organic compounds that are harmful for human health and the environment. However, the WPU has low weathering resistance. In order to improve this behavior among others properties, inorganic fillers has been added in these systems. SiO2 particles from various sources, mainly, from agro-industrial waste, as rice husk has attracted the scientific and technological interest. In this study, the accelerated weathering essay was performed in waterborne polyurethane (WPU)/ silica (from rice husk ash) composites in order to evaluate the thermal and physical changes in these materials. These... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Waterborne polyurethane; Rice husk ash; Silica; Accelerated weathering resistance. |
| Ano: 2019 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652019000700403 |
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| Pittol,Michele; Tomacheski,Daiane; Simões,Douglas Naue; Ribeiro,Vanda Ferreira; Santana,Ruth Marlene Campomanes. |
| ABSTRACT The increasing concern over the spread of diseases has lead to a high consumption of antimicrobial additives in the medical and industrial fields. Since these particles can lixiviate from loaded materials, the contact between this additive and mammalian cells can occur during manufacture, use and disposal of the products. Silver on fumed silica (AgNP_SiO2) and titanium dioxide (TiO2) can be used as antimicrobial additives that are applied in polymeric formulation. While these additives can inhibit bacteria, fungus and virus proliferation; they may also be harmful to humans. Standard toxicological studies were undertaken using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide), CBPI (cytokinesis-block proliferation index) and... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Titanium dioxide; Silver; Silica; Toxicology; Mammalian cell. |
| Ano: 2018 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132018000100318 |
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| Registros recuperados: 15 | |
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