Repositório Colecção: Artigos/Papers (with refereeing)Artigos/Papers (with refereeing)https://hdl.handle.net/1822/19112024-03-29T14:56:36Z2024-03-29T14:56:36ZHighly fluorescent 2‐Aminopurine derivatives: synthesis, photo‐physical characterization, and preliminary cytotoxicity evaluationGonçalves, Jorge M.Gonçalves, João N. D.Pêra, Ana S.Senhorães, Nádia R.Rodrigues, Ana Rita OliveiraOliveira, Rui Pedro Soares deCoutinho, Paulo J. G.Castanheira, Elisabete M. S.Dias, Alicehttps://hdl.handle.net/1822/894452024-03-12T21:06:01ZTítulo: Highly fluorescent 2‐Aminopurine derivatives: synthesis, photo‐physical characterization, and preliminary cytotoxicity evaluation
Autor: Gonçalves, Jorge M.; Gonçalves, João N. D.; Pêra, Ana S.; Senhorães, Nádia R.; Rodrigues, Ana Rita Oliveira; Oliveira, Rui Pedro Soares de; Coutinho, Paulo J. G.; Castanheira, Elisabete M. S.; Dias, Alice
Resumo: New fluorescent nucleobase analogues (FBAs) are emerg-ing as extraordinarily useful tools for DNA labelling tech-nologies. The highly fluorescent adenine analogue 2 aminopurine (2AP) is still the most used within the few hundreds of newly FBAs synthesized, but its excitation in the UV region demands for high energy sources endanger-ing living cells. New and highly fluorescent 2AP deriva-tives, 2-amino-6-cyanopurines, were obtained using novel, simpler, but very efficient synthesis method. All the new compounds exhibit advantageous photophysical properties over 2AP, showing absorption and emission bands ranging the visible region (blue-green region), high fluorescence quantum yields and Stokes’ shifts, especially in non-protic organic solvents. Density Functional Theory calculations (DFT) of electronic and vibrational structure were per-formed, allowing to predict absorption and emission spec-tra in accordance with experimental data. The extensive solvatochromism of compounds gives them important microenvironmental sensitivity to be used as superior fluorescent probes, comparing to 2AP. In addition, these newly synthesized 2-amino-6-cyanopurines exhibit little to no toxicity in assays using yeast cells, making them also valuable candidates for fluorescent studies in living cells.
Descrição: First published: 15 March 2023
<b>Tipo</b>: articleThe buzz on insecticides: a review of uses, molecular structures, targets, adverse effects, and alternativesAraújo, Maria F.Castanheira, Elisabete M. S.Sousa, Sérgio F.https://hdl.handle.net/1822/845362023-05-29T16:04:23Z2023-05-17T13:38:41ZTítulo: The buzz on insecticides: a review of uses, molecular structures, targets, adverse effects, and alternatives
Autor: Araújo, Maria F.; Castanheira, Elisabete M. S.; Sousa, Sérgio F.
Resumo: Insecticides play a critical role in controlling the spread of insect-borne diseases and preserving crop health. These chemical substances are specifically formulated to kill or manage insect populations. Over the years, various types of insecticides have been developed, including organophosphates, carbamates, pyrethroids, and neonicotinoids, each with unique modes of action, physiological targets, and efficacy. Despite the advantages that insecticides offer, it is imperative to recognize the potential consequences on non-target species, the environment, and human health. It is therefore crucial to follow recommended label instructions and employ integrated pest management practices for the judicious use of insecticides. This review article provides an in-depth examination of the various types of insecticides, including their modes of action, physiological targets, environmental and human health impacts, and alternatives. The aim is to furnish a comprehensive overview of insecticides and to emphasize the significance of responsible and sustainable utilization.
<b>Tipo</b>: article2023-05-17T13:38:41ZElectrospun fibers with highly polarized second harmonic light from 2-amino-4-nitroaniline and 3-nitroaniline nanocrystals embedded in poly-L-lactic acid polymerBaptista, Rosa M. F.Bernardo, Cesar R.Belsley, M.de Matos Gomes, Etelvinahttps://hdl.handle.net/1822/804072022-11-09T10:46:14ZTítulo: Electrospun fibers with highly polarized second harmonic light from 2-amino-4-nitroaniline and 3-nitroaniline nanocrystals embedded in poly-L-lactic acid polymer
Autor: Baptista, Rosa M. F.; Bernardo, Cesar R.; Belsley, M.; de Matos Gomes, Etelvina
Resumo: Nanofibers consisting of organic optical nonlinear 2-amino-4-nitroaniline (2A4NA, C6H7N3O2) and 3-nitroaniline (3NA, C6H6N2O2) nanocrystals embedded in poly-L-lactic acid (PLLA) polymer were fabricated by the electrospinning technique. Intense anisotropic polarized second harmonic emission was observed from the molecular nanocrystals embedded within the nano and microfibers. The effective second-order susceptibility coefficients determined for the embedded 2A4NA and 3NA nanocrystals have magnitudes of 42 pmV-1 and 56 pmV-1 respectively, which are among the highest measured for organic nonlinear crystals. X-ray diffraction data revealed preferential crystallographic orientation of the molecules crystallized inside the nanofibers and calculations indicate average crystallite sizes of 33.5 nm and 21.7 nm, respectively for 2A4NA and 3NA. The present work follows previous studies on the nanofabrication, by the electrospinning technique, of polymer nanofibers doped with highly hyperpolarizable para-nitroaniline (C6H6N2O2) derivative push-pull molecules. These hybrid functional nano-systems display strong and directional nonlinear optical responses and establish the technique as a viable method for creating subwavelength scale generators of second harmonic light.
<b>Tipo</b>: articleLiDAR – Tudo na luz é informaçãoRomanyshyn, NazarDuarte, MCunha, N. F.Pereira, Mário R.Vasilevskiy, Mikhailhttps://hdl.handle.net/1822/799582022-10-07T16:49:32ZTítulo: LiDAR – Tudo na luz é informação
Autor: Romanyshyn, Nazar; Duarte, M; Cunha, N. F.; Pereira, Mário R.; Vasilevskiy, Mikhail
Resumo: O que têm em comum o caminho da lua no mar e a condução autónoma de veículos? A reflexão difusa da luz em superfícies rugosas e materiais heterogêneos é responsável pela visibilidade de objetos que não conseguiríamos ver de acordo com a lei de Snell. O mesmo fenómeno ótico também está na base do funcionamento de sensores remotos chamados LIDARs (abreviação de Light Detection And Ranging) que surgiram nos anos 60 do século XX nos Estados Unidos e na União Soviética com a finalidade de medir a distância a objetos, estudar superfícies inacessíveis (como a da Lua) e analisar a atmosfera. As aplicações atuais também incluem a geodesia, topografia e arqueologia, como um dos instrumentos de mapeamento, e a mobilidade, em sistemas de condução autónoma de veículos.
<b>Tipo</b>: articleAssessment of zirconia fluorescence after treatment with immersion in liquids, glass infiltration and agingVolpato, Claudia A. M.Carvalho, Óscar Samuel NovaisVolpato, Guilherme M.Fredel, Márcio C.Silva, Filipe SamuelPereira, Mário R.https://hdl.handle.net/1822/797592022-09-28T20:36:59ZTítulo: Assessment of zirconia fluorescence after treatment with immersion in liquids, glass infiltration and aging
Autor: Volpato, Claudia A. M.; Carvalho, Óscar Samuel Novais; Volpato, Guilherme M.; Fredel, Márcio C.; Silva, Filipe Samuel; Pereira, Mário R.
Resumo: The aim of this study was to evaluate the fluorescence of white zirconia immersed in coloring and fluorescence liquids subjected to glass infiltration and aging. Sixty zirconia discs were machined and divided into groups. Ten discs received no treated before sintering (NT group), ten discs were immersed in a coloring liquid (A2 group), and ten discs were immersed in a fluorescent liquid (F group). The other thirty discs were infiltrated by glass after the previous treatments (NT+I, A2+I, and F+I groups). The composition of the commercial liquids was characterized by X-Ray fluorescence. Diffuse reflectance and total fluorescence were evaluated before and after the aging protocol, made in autoclave for 4 hours at 134 °C. The X-Ray fluorescence analysis found a high concentration of Fe2O3 (80.7 at%) in the composition of the coloring liquid and of Bi2O3 (54.2 at%) and Cl (45.2 at%) in the fluorescence liquid. Greater reflectance was observed in the glass infiltrated groups, in particular NT+I and F+I. Fluorescence 3D maps of the groups submitted to immersion showed a higher total fluorescence than the NT group, except for the A2 group. The F group showed the highest fluorescence, being 12.8 times greater than the NT group. The fluorescence emission occurred in the region between 350 and 550 nm after an excitation between 290 and 360 nm. Regarding aging, the presence of the glass infiltrated layer protected the samples from hydrothermal degradation.
<b>Tipo</b>: article