3,509 research outputs found
Alguns contributos da nanotecnologia para a sustentabilidade dos materiais de construção
Os avanços nanotecnológicos atingem inúmeras áreas da ciência, mas no âmbito da sustentabilidade dos materiais de construção os progressos embora importantes são escassos e acima de tudo objeto de reduzida divulgação. O presente artigo sintetiza uma avaliação do
estado da arte relativa a alguns dos contributos da nanotecnologia para a sustentabilidade dos materiais de construção. No mesmo se aborda a compreensão dos compostos gerados durante a hidratação do cimento Portland, o aumento da resistência e da durabilidade de argamassas e betões pela adição de nanopartículas e nanotubos e de que forma a adição de nanopartículas pode contribuir para a autolimpeza, a purificação do ar e a capacidade bactericida em materiais
construtivos por via do efeito fotocatalítico. O presente artigo aborda ainda os últimos
desenvolvimentos da nanotecnologia com vista à eficiência energética, nomeadamente pela produção de isolamentos térmicos de elevado desempenho, janelas com baixa condutibilidade térmica, vidros com transmitância variável e materiais de mudança de fase mais eficientes
Monitoring cell detachment by surfactants in a parallel plate flow chamber
The efficacy of the surfactants SDS and CTAB in detaching P. fluorescens from glass surface was evaluated in a
parallel plate flow chamber. This device enables “in situ” determinations of cells detachment following the application of
surfactants under well controlled hydrodynamic conditions. The results showed that SDS was able to remove almost all
adhering bacteria in a short period of time, whereas CTAB did not promote much cell desorption. On the contrary, this
surfactant increased the adhesion strength between cells and glass. Both surfactants promoted different alterations of cell
surface properties, which explains their dissimilar effectiveness as cleansing agents.programme SAPIEN
Ex vivo exposure to titanium dioxide and silver nanoparticles mildly affect sperm of gilthead seabream (Sparus aurata) - A multiparameter spermiotoxicity approach
Nanoparticles (NP) are potentially repmtoxic, which may compromise the success of populations. However, the reprotoxicity of NP is still scarcely addressed in marine fish. Therefore, we evaluated the impacts of environmentally relevant and supra environmental concentrations of titanium dioxide (TiO2: 10 to 10,000 mu g.L-1) and silver NP (Ag: 0.25 to 250 mu g.L-1) on the sperm of gilthead seabream (Sparus aurata). We performed short-term direct exposures (ex vivo) and evaluated sperm motility, head morphometry, mitochondrial function, antioxidant responses and DNA integrity. No alteration in sperm motility (except for supra environmental Ag NP concentration), head morphometry, mitochondrial function, and DNA integrity occurred. However, depletion of all antioxidants occurred after exposure to TiO2 NP, whereas SOD decreased after exposure to Ag NP (lowest and intermediate concentration). Considering our results, the decrease in antioxidants did not indicate vulnerability towards oxidative stress. TiO2 NP and Ag NP induced low spermiotoxicity, without proven relevant ecological impacts.info:eu-repo/semantics/publishedVersio
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