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Laboratory for Instrumentation, Biomedical Engineering and Radiation Physics
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Effect of Applied Electrical Stimuli to Interdigitated Electrode Sensors While Detecting 17α-Ethinylestradiol in Water Samples
Publication . Zagalo, Paulo M.; Ribeiro, Paulo A.; Raposo, Maria; CeFITec – Centro de Física e Investigação Tecnológica; DF – Departamento de Física; LIBPhys-UNL; MDPI - Multidisciplinary Digital Publishing Institute
The effect of impedance measurements of applied voltage on the detection of 17α-ethiny lestradiol (EE2) in water samples using interdigitated electrodes (IDE) coated or not with thin films, is described. Firstly, the effect of immersion in EE2 aqueous solutions of layer-by-layer films prepared with poly(allylamine hydrochloride) (PAH), graphene oxide (GO), poly(1-(4-(3-carboxy-4-hydroxyphenylazo) benzene sulfonamido) 1,2 ethanediyl, sodium salt) (PAZO), polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS) was analyzed. These results demonstrated that PAH/GO films desorb during the immersion on EE2 solutions, while EE2 adsorbs on PAH/PAZO and PEI/PSS films with characteristic time values of 16.7 and 7.1 min, respectively, demonstrating that both films are adequate for the development of EE2 sensors. However, as the adsorption characteristic time is shorter, and the EE2 adsorbed amount is smaller, the PEI/PSS films are more suitable for the development of sensors. The effect of the applied voltage was analyzed using both IDEs covered with PEI/PSS films as well as those uncoated. The capacitance spectra are best fitted to analyze this effect, and the loss tangent spectra are advantageous to analyze the aqueous media. Furthermore, it was concluded that lower voltage values are best suited to perform measurements of this nature, given that higher voltages lead to less reliable results and cause irreparable damage to the sensors.
Graphene Oxide Thin Films for Detection and Quantification of Industrially Relevant Alcohols and Acetic Acid
Publication . Moura, Pedro Catalão; Pivetta, Thais Priscilla; Vassilenko, Valentina; Ribeiro, Paulo António; Raposo, Maria; DF – Departamento de Física; LIBPhys-UNL; MDPI - Multidisciplinary Digital Publishing Institute
Industrial environments are frequently composed of potentially toxic and hazardous compounds. Volatile organic compounds (VOCs) are one of the most concerning categories of analytes commonly existent in the indoor air of factories’ facilities. The sources of VOCs in the industrial context are abundant and a vast range of human health conditions and pathologies are known to be caused by both short- and long-term exposures. Hence, accurate and rapid detection, identification, and quantification of VOCs in industrial environments are mandatory issues. This work demonstrates that graphene oxide (GO) thin films can be used to distinguish acetic acid, ethanol, isopropanol, and methanol, major analytes for the field of industrial air quality, using the electronic nose concept based on impedance spectra measurements. The data were treated by principal component analysis. The sensor consists of polyethyleneimine (PEI) and GO layer-by-layer films deposited on ceramic supports coated with gold interdigitated electrodes. The electrical characterization of this sensor in the presence of the VOCs allows the identification of acetic acid in the concentration range from 24 to 120 ppm, and of ethanol, isopropanol, and methanol in a concentration range from 18 to 90 ppm, respectively. Moreover, the results allows the quantification of acetic acid, ethanol, and isopropanol concentrations with sensitivity values of (Formula presented.), (Formula presented.), and (Formula presented.) mL−1, respectively. The resolution of this sensor to detect the different analytes is lower than 0.04 ppm, which means it is an interesting sensor for use as an electronic nose for the detection of VOCs.
Application of wearable technology for the ergonomic risk assessment of healthcare professionals
Publication . Sabino, Inês; Fernandes, Maria do Carmo; Cepeda, Cátia; Quaresma, Cláudia; Gamboa, Hugo; Nunes, Isabel L.; Gabriel, Ana Teresa; DEMI - Departamento de Engenharia Mecânica e Industrial; DF – Departamento de Física; LIBPhys-UNL; UNIDEMI - Unidade de Investigação e Desenvolvimento em Engenharia Mecânica e Industrial; Elsevier Science B.V., Amsterdam.
Healthcare professionals are exposed to multiple physical risk factors related to the development of work-related musculoskeletal disorders (WRMSD), which significantly affect their quality of life. Several ergonomic methods have been developed for identifying risk factors in the workplace. Among these, wearable devices that perform direct measurements have demonstrated outstanding potential in recent years to provide reliable, non-invasive, and continuous exposure assessment. Therefore, this systematic review aims to describe the use of wearable technology for the ergonomic risk assessment of healthcare professionals. Twenty-nine publications were selected following PRISMA guidelines based on the inclusion and exclusion criteria set. Most of the articles were published in the last three years, confirming a growing trend in the research on this topic. Most wearable devices, which were used isolated or combined, consist of inertial sensors used to measure and assess the exposure to awkward postures and sEMG sensors, which provide the measurement of muscle activity parameters related to the force applied while performing work activities. The main results and respective analyses provided insights into the strengths and limitations of using wearable technology to acquire data on several work activities performed by healthcare professionals. Future research is needed to widen and validate the applicability of wearable technology in support of ergonomic interventions aimed at preventing the development of WRMSD among healthcare professionals.
Phototoxic Potential of Different DNA Intercalators for Skin Cancer Therapy
Publication . Pivetta, Thais P.; Vieira, Tânia; Silva, Jorge C.; Ribeiro, Paulo A.; Raposo, Maria; DF – Departamento de Física; CeFITec – Centro de Física e Investigação Tecnológica; LIBPhys-UNL; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); MDPI - Multidisciplinary Digital Publishing Institute
Photodynamic therapy is a minimally invasive procedure used in the treatment of several diseases, including some types of cancer. It is based on photosensitizer molecules, which, in the presence of oxygen and light, lead to the formation of reactive oxygen species (ROS) and consequent cell death. The selection of the photosensitizer molecule is important for the therapy efficiency; therefore, many molecules such as dyes, natural products and metallic complexes have been investigated regarding their photosensitizing potential. In this work, the phototoxic potential of the DNA-intercalating molecules—the dyes methylene blue (MB), acridine orange (AO) and gentian violet (GV); the natural products curcumin (CUR), quercetin (QT) and epigallocatechin gallate (EGCG); and the chelating compounds neocuproine (NEO), 1,10-phenanthroline (PHE) and 2,2′-bipyridyl (BIPY)—were analyzed. The cytotoxicity of these chemicals was tested in vitro in non-cancer keratinocytes (HaCaT) and squamous cell carcinoma (MET1) cell lines. A phototoxicity assay and the detection of intracellular ROS were performed in MET1 cells. Results revealed that the IC50 values of the dyes and curcumin in MET1 cells were lower than 30 µM, while the values for the natural products QT and EGCG and the chelating agents BIPY and PHE were higher than 100 µM. The IC50 of MB and AO was greatly affected by irradiation when submitted to 640 nm and 457 nm light sources, respectively. ROS detection was more evident for cells treated with AO at low concentrations. In studies with the melanoma cell line WM983b, cells were more resistant to MB and AO and presented slightly higher IC50 values, in line with the results of the phototoxicity assays. This study reveals that many molecules can act as photosensitizers, but the effect depends on the cell line and the concentration of the chemical. Finally, significant photosensitizing activity of acridine orange at low concentrations and moderate light doses was demonstrated.
Diffusion of muonic hydrogen in hydrogen gas and the measurement of the 1s hyperfine splitting of muonic hydrogen
Publication . Nuber, J.; Adamczak, A.; Abdou Ahmed, M.; Affolter, L.; Amaro, F. D.; Amaro, P.; Antognini, A.; Carvalho, P.; Chang, Y. H.; Chen, T. L.; Chen, W. L.; Fernandes, L. M. P.; Ferro, M.; Goeldi, D.; Graf, T.; Guerra, M.; Hänsch, T. W.; Henriques, C. A. O.; Hildebrandt, M.; Indelicato, P.; Kara, O.; Kirch, K.; Knecht, A.; Kottmann, F.; Liu, Y. W.; Machado, J.; Marszalek, M.; Mano, R. D. P.; Monteiro, C. M. B.; Nez, F.; Ouf, A.; Paul, N.; Pohl, R.; Rapisarda, E.; dos Santos, J. M. F.; Santos, J. P.; Silva, P. A.O. C.; Sinkunaite, L.; Shy, J. T.; Schuhmann, K.; Rajamohanan, S.; Soter, A.; Sustelo, L.; Taqqu, D.; Wang, L. B.; Wauters, F.; Yzombard, P.; Zeyen, M.; Zhang, J.; DF – Departamento de Física; LIBPhys-UNL; Institute of Economic Research, Nicolaus Copernicus University
The CREMA collaboration is pursuing a measurement of the ground-state hyperfine splitting (HFS) in muonic hydrogen (µp) with 1 ppm accuracy by means of pulsed laser spectroscopy. In the proposed experiment, the µp atom is excited by a laser pulse from the singlet to the triplet hyperfine sub-levels, and is quenched back to the singlet state by an inelastic collision with a H2 molecule. The resulting increase of kinetic energy after this cycle modifies the µp atom diffusion in the hydrogen gas and the arrival time of the µp atoms at the target walls. This laser-induced modification of the arrival times is used to expose the atomic transition. In this paper we present the simulation of the µp diffusion in the H2 gas which is at the core of the experimental scheme. These simulations have been implemented with the Geant4 framework by introducing various low-energy processes including the motion of the H2 molecules, i.e. the effects related with the hydrogen target temperature. The simulations have been used to optimize the hydrogen target parameters (pressure, temperatures and thickness) and to estimate signal and background rates. These rates allow to estimate the maximum time needed to find the resonance and the statistical accuracy of the spectroscopy experiment.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04559/2020