Digital electric field induced switching of plasmonic nanorods using an electro-optic fluid fiber

We demonstrate the digital electric field induced switching of plasmonic nanorods between 1 and 0 orthogonal aligned states using an electro-optic fluid fiber component. We show by digitally switching the nanorods, that thermal rotational diffusion of the nanorods can be circumvented, demonstrating an approach to achieve submicrosecond switching times. We also show, from an initial unaligned state, that the nanorods can be aligned into the applied electric field direction in 110 nanoseconds. The high-speed digital switching of plasmonic nanorods integrated into an all-fiber optical component may provide novel opportunities for remote sensing and signaling applications

Bleaching of sol-gel glass film with embedded gold nanoparticles by thermal poling

Gold clusters embedded in glass are expected to be hard to dissolve in the form of ions since gold is essentially a nonreactive metal. In spite of that, bleaching of Au-doped nanocomposite sol-gel glass film on a soda-lime glass substrate is demonstrated in which electric-field thermal poling is employed to effectively dissolve randomly distributed gold nanoparticles (15 nm in diameter) embedded in a low conductivity sol-gel glass film with a volume filling factor as small as 2.3%. The surface plasmon absorption band at 520 nm is suppressed in the region covered by the anodic electrode. The phenomenon is explained by the ionization of the gold nanoparticles and the redistribution of gold ions in the glass matrix due to the action of the extremely high electrostatic field locally developed during poling

Mulheres Licenciadas e a Promoção do Desenvolvimento em Angola: Que diferença faz o Ensino Superior?

A educação é um direito universal e uma ferramenta fundamental para o desenvolvimento das capacidades dos indivíduos e da sociedade. Em Angola, baixas taxas de qualificação da população estão associadas com as mais altas taxas de pobreza e exclusão social, desemprego, analfabetismo, mortalidade infantil, incidência de HIV, malária e tuberculose, entre outras. Níveis mais elevados de educação promovem maior bem-estar e qualidade de vida, por via dos rendimentos auferidos e, mulheres mais qualificadas terão tendência a melhorar o seu estatuto na sociedade e a modificar o seu estilo de vida. Por outro lado é expectável que motivem, de forma natural, à sua descendência a importância da aprendizagem e da aquisição de conhecimentos. Esta questão é particularmente pertinente em sociedades onde as mulheres desempenham um papel determinante na economia. Do ponto de vista da sustentabilidade dos territórios, podem contribuir ainda para a construção de uma sociedade mais sustentável. O presente trabalho tem como objectivo identificar a importância da obtenção de uma licenciatura na valorização social e económica das mulheres angolanas e, consequentemente na promoção do desenvolvimento da sociedade. Para tal, apresentam-se os resultados preliminares de um estudo exploratório de natureza qualitativa com base numa entrevista aplicada a uma amostra de conveniência de mulheres angolanas licenciadas. Os resultados permitem aferir a importância das mulheres licenciadas na promoção do desenvolvimento em Angola e sugerem tópicos para futuras pesquisas

An International Collaboration to Promote Inquiry-based Learning in Undergraduate Engineering Classrooms

Abstract Theorists such as Bransford et al. argue that twenty-first century educators need to teach students to do more than simply remember and repeat information. Engineering educators Prince and Felder critique traditional methods of teaching in which instructors focus on mathematics and theory, but fail to convey practical applications of that knowledge. They advocate moving students to a higher level of learning -past the stage of memorizing and reciting data -to more sophisticated methods of analysis, synthesis, and application of knowledge. To enact such transformations, Prince and Felder recommend "inductive teaching methods," including "inquiry-based learning," in which students learn through engaging with challenges and a series of questions. The purpose of this paper is to describe specific techniques of "inquiry-based learning" employed by three instructors in Engineering schools, one in Europe and two in the USA. The paper provides examples of inquiry-based learning activities from each of the authors. The paper then discusses the cross-pollination of ideas and describes how the authors have shared inquiry-based teaching strategies and collaborated to develop new and relevant assignments and approaches to teaching

Impact of SiO2 nanoparticle morphology on scattering efficiency for random lasers

In this work, we compared the effect of Quartzite nanoparticles (QtzNP - crystalline SiO2) and amorphous silica nanoparticles (ASNP) as scatters in a random laser (RL), correlating the laser efficiency to the morphology and refractive index (RI) of the scatterers. The RL was based on a laser media containing suspensions of QtzNPs or ASNPs in Rhodamine 6G (Rh6G) and ethylene glycol (EG) suspension. It was observed a considerable increase in RL efficiency for QtzNPs, as compared to ASNPs, even for concentrations as low as 0.5mg/mL. Such grow in the RL eficiency is attributed to the higher RI of QtzNPs (n=1.54), which in-creases the reflectance of light on the particles surface and the high field scattering intensity in the sharp edges of the flat slab shapes, associated to the particle's morphology. Finite Element Method (FEM) simu-lations were also performed for different particle size and shapes and an output increase is noticed for QtzNPs when compared with the ASNP confirming the experimental results. The comparison between the morphology of QtzNPs and ASNPs on scattering efficiency reported here contribute to optimize the performance of laser systems with natural and synthetic nanomaterials

Assessment of metal and metalloid contamination in the waters and stream sediments around the abandoned uranium mine area from Mortórios, central Portugal

In the abandoned Mortórios uranium mine area there are quartz veins containing wolframite and sulphides and basic rock dykes with torbernite and autunite cutting a porphyritic granite. The basic rock dykes were exploited and produced about 27 tonnes of U3O8, from 1982 to 1988. There are an open pit lake and nine dumps. Surface water and groundwater are contaminated in U, As, Cd, Cr, Cu, Fe, Mn, Ni and Pb. Stream sediments are contaminated in U, As, Th and W, which are adsorbed by smectite, kaolinite and iron- and aluminium- oxy-hydroxides. The maximum U concentrations are of 1268 ug/L in the open pit lake, 100 g/L in surface water, 103 ug/L in groundwater and 81.5 mg/kg in stream sediments all downstream of the open pit lake and dumps. Further downstream the U concentration in water decreases, due to the high mobility of U (VI), but the U concentration in stream sediments increases. Calcium uranyl carbonate dominates in the open pit lake, but uranyl carbonate complexes dominate in surface water and groundwater. The maximum As concentrations are 56.0 g/L in the open pit lake, 63.4 g/L in the surface water and 66.7 g/L in the groundwater, both downstream of the open pit lake and dumps. The arsenic occurs as As (V). The Mortórios area is compared with two other areas exploited from open pits, all located in the uranium-bearing Beira area of central Portugal. Vale de Abrutiga produced 90 tonnes of U3O8 between 1982 and 1989 and Mondego Sul produced 75 tonnes of U3O8 from 1987 to 1991. The two mines consist of quartz veins containing sulphides, saleeite and meta-saleeite at Vale de Abrutiga and with sulphides, autunite, torbernite, meta-uranocircite and meta-saleeite at Mondego Sul cutting the Schist-graywacke complex. The mine area of Vale de Abrutiga with the highest exploitation of U2O3 has strongly acidic to slight alkaline water, which is the most contaminated. Mortórios with the lowest exploitation presents a higher contamination of slightly acidic to alkaline water than that of acidic to alkaline water from Mondego Sul, but the former has As (V), whereas the latter has As (III), which is toxic. The stream sediments from Mortórios present the lowest contamination, except for Th that has a higher median value than that from Vale de Abrutiga. Stream sediments from Mondego Sul have higher U, Th, Pb and lower Co, Cr, Cu and Zn median values than those of Vale de Abrutiga.We are grateful to J.F.C. Mendes for the determination of organic matter and cation exchange capacity in samples of stream sediments. We thank Robert Ayuso and three anonymous reviewers for their comments. Some financial support was given by the project UID/GEO/04035/2013

Metal ion-zeolite nanomaterials for chemodynamic therapy

A new therapeutic approach called chemodynamic therapy (CDT), which can be defined as specific OH generation in cancer cells via Fenton reactions, was recently proposed.1 The advantages of CDT can be ascribed to the higher specificity, no external field penetration depth restriction, lower side effects in normal tissues, higher-level ROS generation, lack of equipment restrictions, and non-multidrug resistance, showing the promising future of CDT for clinical translation. The varied and highly controlled structural along with the chemical properties of inorganic nanomaterials, like zeolites, make them suitable for this type of CDT. Zeolites already proved to be interesting candidates for medical and healthcare applications, and also as Fenton heterogeneous catalysts for organic degradation. The aim of this study was to assess the dual activity (antibacterial and anticancer) of metal ion-zeolite nanomaterials. The prepared metal ion-zeolite nanomaterials were tested in vitro using a human skin cancer cell line, A375, and the anti-bacterial activity was evaluated against Escherichia coli, Staphylococcus aureus and MRSA. Results obtained so far suggest that metal ion-zeolite nanomaterials could be explored as antibacterial and/or anticancer agents.info:eu-repo/semantics/publishedVersio

Flexible random lasers in dye-doped bio-degradable cellulose nanocrystalline needles

M-ERA-NET2/0007/2016 POCI-01-0145-FEDER-007688 PTDC/CTM-BIO/6178/2014 PTDC/CTM-REF/30529/2017 UID/CTM/50025In this work, we developed and investigated a random laser based on rhodamine6G (Rh6G) in ethylene glycol (EG) solution with varying cellulose nanocrystalline (CNC) needles as scatterers in the lasing media. Besides the suspension-in-cuvette scheme, an alternative configuration was also employed: a dye-CNC flexible self-supported thick-film (70 µm) random laser made by drop casting of the CNCs + Rh6G + hydroxypropyl cellulose suspension. In relation to conventional scatterers, the biodegradable cellulose nanocompounds showed a comparable reduction in both the spectral full width at half-maximum and the energy threshold values, with an optimal concentration of 5 mg [CNC]/ml[EG] in suspension. Its performance was also compared with other cellulose-based random lasers, presenting advantages for some parameters. The flexible film configuration showed similar results, but contained 10% less Rh6G than the suspension.authorsversionpublishe

Assessment of metal and metalloid contamination in soils trough compositional data: the old Mortórios uranium mine area, central Portugal

Soils from the old Mortórios uranium mine area were studied to look for contamination, as they are close to two villages, up to 3 km away, and used for agriculture. They are mainly contaminated in U and As and constitute an ecological threat. This study attempts to outline the degree to which soils have been affected by the old mining activities through the computation of significant hot clusters, Traditional geostatistical approaches commonly use raw data (concentrations) accepting that the analyzed elements represent the soil’s entirety. However, in geochemical studies these elements are just a fraction of the total soil composition. Thus, considering compositional data is pivotal. The spatial characterization, considering raw and compositional data together, allowed a broad discussion about not only the concentrations’ spatial distribution, but also a better understanding on the possibility of trends of “relative enrichment” (RE) and, furthermore an insight in U and As fate. The highest proportions (Compositional data) on U (up to 33%), As (up to 35%) and Th (up to 13 %) are reached in the south-southeast segment. However, the highest concentrations (Raw data) occur in north and northwest of the studied area, pointing out to a “relative enrichment” towards the south-southeast zone. The Mondego Sul area is mainly contaminated in U and As, but also in Co, Cu, Pb and Sb. The Mortórios area is less contaminated than the Mondego Sul area.This research was supported by the Fundação para a Ciência e a Tecnologia through projects UID/ GEO/04035/201C and UID/MAR/04292/2013-MARE (PPC). Boente obtained a grant from the ‘‘Formación del Profesorado Universitario’’ program, financed by the ‘‘Ministerio de Educación, Cultura y Deporte de España.’’ M.T.D Albuquerque acknowledges a scholarship 567 SFRH/BSAB/ 127907/2016 from the Foundation for Science and Technology (Portugal)