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result(s) for
"Silva, Nuno O."
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In situ functionalization of a cellulosic-based activated carbon with magnetic iron oxides for the removal of carbamazepine from wastewater
by
Pereira, Diogo
,
Calisto, Vânia
,
Rocha, Luciana S
in
Activated carbon
,
Adsorption
,
Adsorptivity
2021
The main goal of this work was to produce an easily recoverable waste-based magnetic activated carbon (MAC) for an efficient removal of the antiepileptic pharmaceutical carbamazepine (CBZ) from wastewater. For this purpose, the synthesis procedure was optimized and a material (MAC4) providing immediate recuperation from solution, remarkable adsorptive performance and relevant properties (specific surface area of 551 m2 g-1 and saturation magnetization of 39.84 emu g-1) was selected for further CBZ kinetic and equilibrium adsorption studies. MAC4 presented fast CBZ adsorption rates and short equilibrium times (< 30-45 min) in both ultrapure water and wastewater. Equilibrium studies showed that MAC4 attained maximum adsorption capacities (qm) of 68 ± 4 mg g-1 in ultrapure water and 60 ± 3 mg g-1 in wastewater, suggesting no significant interference of the aqueous matrix in the adsorption process. Overall, this work provides evidence of potential application of a waste-based MAC in the tertiary treatment of wastewaters.
Journal Article
Comparison between AI and human expert performance in acute pain assessment in sheep
by
Trindade, Pedro E.
,
Shimshoni, Ilan
,
Luna, Stelio P.
in
631/601/18
,
692/1807/410
,
Acute Pain - diagnosis
2025
This study explores the question whether Artificial Intelligence (AI) can outperform human experts in animal pain recognition using sheep as a case study. It uses a dataset of N = 48 sheep undergoing surgery with video recordings taken before (no pain) and after (pain) surgery. Four veterinary experts used two types of pain scoring scales: the sheep facial expression scale (SFPES) and the Unesp-Botucatu composite behavioral scale (USAPS), which is the ‘golden standard’ in sheep pain assessment. The developed AI pipeline based on CLIP encoder significantly outperformed human facial scoring (AUC difference = 0.115,
p
< 0.001) when having access to the same visual information (front and lateral face images). It further effectively equaled human USAPS behavioral scoring (AUC difference = 0.027,
p
= 0.163), but the small improvement was not statistically significant. The fact that the machine can outperform human experts in recognizing pain in sheep when exposed to the same visual information has significant implications for clinical practice, which warrant further scientific discussion.
Journal Article
Enabling Real‐Time, Non‐Ionizing 3D Imaging of Implantable Magnetic Cements Using Magnetic Particle Imaging
by
C. Pinto, Gabriel
,
Silva, Ricardo M.
,
Vogel, Patrick
in
Anisotropy
,
Biocompatibility
,
Cements
2026
Magnetic Particle Imaging (MPI) is a non‐ionizing tomographic technique capable of real‐time 3D imaging with unmatched temporal resolution, reaching up to 46 vol/s. These features make MPI a promising tool for the monitoring of implantable resin composites, particularly in scenarios requiring frequent safe, and dynamic assessment. However, integrating magnetic responsiveness into medical materials without compromising their structural and biological integrity remains a challenge. In this study, it is presented the first strategy to enable MPI signal generation in a commercial implantable cement by depositing a continuous iron thin film onto its surface. This structured magnetic layer introduces directional magnetic anisotropy, resulting in an angle‐dependent MPI signal. This directional dependence can be explored to noninvasively track for the position and orientation of the implant, potentially benefiting applications in confined anatomical regions. In vitro assays confirmed that the incorporation of the magnetic layer does not compromise cytocompatibility. Altogether, these findings demonstrate that magnetic thin films can serve as anisotropic contrast sources for MPI, expanding the range of new possibilities for imaging implantable materials with orientation‐sensitive contrast and without ionizing radiation. This study reports the first implantable resin cement capable of orientation‐sensitive Magnetic Particle Imaging (MPI). By coating the cement with an ultrathin iron film, the authors achieve a strong, angle‐dependent MPI signal that enables non‐ionizing, real‐time tracking of both implant position and orientation, opening new possibilities for safe, longitudinal monitoring of medical implants.
Journal Article
Integrated Optical Mach-Zehnder Interferometer Based on Organic-Inorganic Hybrids for Photonics-on-a-Chip Biosensing Applications
2018
The development of portable low-cost integrated optics-based biosensors for photonics-on-a-chip devices for real-time diagnosis are of great interest, offering significant advantages over current analytical methods. We report the fabrication and characterization of an optical sensor based on a Mach-Zehnder interferometer to monitor the growing concentration of bacteria in a liquid medium. The device pattern was imprinted on transparent self-patternable organic-inorganic di-ureasil hybrid films by direct UV-laser, reducing the complexity and cost production compared with lithographic techniques or three-dimensional (3D) patterning using femtosecond lasers. The sensor performance was evaluated using, as an illustrative example, E. coli cell growth in an aqueous medium. The measured sensitivity (2 × 10−4 RIU) and limit of detection (LOD = 2 × 10−4) are among the best values known for low-refractive index contrast sensors. Furthermore, the di-ureasil hybrid used to produce this biosensor has additional advantages, such as mechanical flexibility, thermal stability, and low insertion losses due to fiber-device refractive index mismatch (~1.49). Therefore, the proposed sensor constitutes a direct, compact, fast, and cost-effective solution for monitoring the concentration of lived-cells.
Journal Article
Magnetic Polyoxometalate@Biochar Catalysts for Selective Acetalization of Glycerol into Fuel Additive
by
Dias, Catarina N.
,
Bruno, Sofia M.
,
Dias, Luís
in
Acetone
,
Alternative energy
,
Biodiesel fuels
2026
The development of sustainable catalysts from renewable resources is a key challenge for reducing the cost of industrial catalytic processes and waste valorization. In this work, low-cost heterogeneous active catalysts were prepared based on pyrolyzed forest residues, forming valuable porous support materials (Biochar) able to efficiently accommodate the highly active heteropolyacid HPW12. Further, magnetic functionality was incorporated in the novel catalytic materials by the impregnation of NiFe2O4. The resulting magnetic composites were characterized by FTIR-ATR, SEM-EDS, ICP-OES, BET, XRD, potentiometric titration and magnetometry. The novel HPW12@NiFe2O4@Biochar composites were able to valorize the glycerol to produce the fuel additive solketal with high conversion and high selectivity after only 3 h of reaction via acetalization reaction with acetone. The biochar catalytic composite prepared from cork presented higher pore size than the same prepared from forest biomass. This property was crucial to achieve the best conversion (89%) and the highest solketal selectivity (96%). Additionally, reusability capacity was verified, supporting the potential of the cork-pyrolyzed-based composites as potential low-cost catalytic material to produce fuel additives, such as solketal, under sustainable conditions. This may contribute one step further toward a future with greener energy, increasing the viability of biodiesel industry waste.
Journal Article
Carrageenan-grafted magnetite nanoparticles as recyclable sorbents for dye removal
by
Daniel-da-Silva, Ana L.
,
Creaney, Bianca
,
Oliveira-Silva, Rui
in
Adsorption
,
Characterization and Evaluation of Materials
,
Chemistry and Materials Science
2015
The efforts dedicated to improving water decontamination procedures have prompted the interest in the development of efficient, inexpensive, and reusable sorbents for the uptake of dye pollutants. In this work, novel sorbents consisting of carrageenan polysaccharides grafted to magnetic iron oxide nanoparticles were prepared. κ- and ι-carrageenan were first chemically modified by carboxymethylation and then covalently attached via amide bond to the surface of aminated silica-coated magnetite nanoparticles, both steps monitored using infrared spectroscopy (FTIR) analysis. The kinetics and the equilibrium behavior of the cationic dye methylene blue (MB) adsorption onto the carrageenan sorbents were investigated. ι-carrageenan sorbents displayed higher MB adsorption capacity that was ascribed to high content of sulfonate groups. Overall, the pseudo-second order equation provided a good description of the adsorption kinetics. The κ-carrageenan sorbents followed an unusual Z-type equilibrium adsorption isotherm whereas the isotherm of ι-carrageenan sorbents, although displaying a conventional shape, could not be successfully predicted by isotherm models commonly used. Noteworthy, both sorbents were long-term stable and could easily be recycled by simply rinsing with KCl aqueous solution. The removal efficiency of κ-carrageenan sorbents was 92 % in the first adsorption cycle and kept high (>80 %) even after six consecutive adsorption/desorption cycles.
Journal Article
Nano-Localized Thermal Analysis and Mapping of Surface and Sub-Surface Thermal Properties Using Scanning Thermal Microscopy (SThM)
by
Pereira, Maria J.
,
Amaral, Vitor S.
,
Amaral, Joao S.
in
Heat transfer
,
Materials Applications
,
Micromachining
2016
Determining and acting on thermo-physical properties at the nanoscale is essential for understanding/managing heat distribution in micro/nanostructured materials and miniaturized devices. Adequate thermal nano-characterization techniques are required to address thermal issues compromising device performance. Scanning thermal microscopy (SThM) is a probing and acting technique based on atomic force microscopy using a nano-probe designed to act as a thermometer and resistive heater, achieving high spatial resolution. Enabling direct observation and mapping of thermal properties such as thermal conductivity, SThM is becoming a powerful tool with a critical role in several fields, from material science to device thermal management. We present an overview of the different thermal probes, followed by the contribution of SThM in three currently significant research topics. First, in thermal conductivity contrast studies of graphene monolayers deposited on different substrates, SThM proves itself a reliable technique to clarify the intriguing thermal properties of graphene, which is considered an important contributor to improve the performance of downscaled devices and materials. Second, SThM’s ability to perform sub-surface imaging is highlighted by thermal conductivity contrast analysis of polymeric composites. Finally, an approach to induce and study local structural transitions in ferromagnetic shape memory alloy Ni–Mn–Ga thin films using localized nano-thermal analysis is presented.
Journal Article
Density Gradient Selection of Colloidal Silver Nanotriangles for Assembling Dye-Particle Plasmophores
by
Paulo, Pedro M. R.
,
Oliveira-Silva, Rui
,
Sousa-Jerónimo, Mariana
in
Antennas
,
Centrifugation
,
colloidal metal nanoparticles
2019
A simple method based on sucrose density gradient centrifugation is proposed here for the fractionation of colloidal silver nanotriangles. This method afforded particle fractions with surface plasmon resonances, spanning from red to infrared spectral ranges that could be used to tune optical properties for plasmonic applications. This feature was exemplified by selecting silver nanotriangle samples with spectral overlap with Atto-655 dye’s absorption and emission in order to assemble dye-particle plasmophores. The emission brightness of an individual plasmophore, as characterized by fluorescence correlation spectroscopy, is at least 1000-fold more intense than that of a single Atto-655 dye label, which renders them as promising platforms for the development of fluorescence-based nanosensors.
Journal Article
Enabling Real‐Time, Non‐Ionizing 3D Imaging of Implantable Magnetic Cements Using Magnetic Particle Imaging (Adv. Mater. Interfaces 7/2026)
by
C. Pinto, Gabriel
,
Silva, Ricardo M.
,
Vogel, Patrick
in
Anisotropy
,
Implantable resin cements
,
Magnetic Particle Imaging
2026
Magnetic Particle Imaging An implantable resin cement coated with a magnetic iron thin film is tracked in real time using Magnetic Particle Imaging (MPI). The artwork highlights its MPI detectability, enabling 3D localization and orientation sensing without ionizing radiation. More details can be found in the Research Article by Gabriel C. Pinto, Nuno J. O. Silva, and co‐workers (DOI: 10.1002/admi.202500757).
Journal Article