Browsing by Issue Date, starting with "2024-06-03"
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- Environmentally friendly and cost-effective approaches to reduce toxin content in toxic cyanobacterial biomassesPublication . Loss, Letícia; Azevedo, Joana; Azevedo, Tomé; Freitas, Marisa; Vasconcelos, Vítor; Campos, AlexandreCyanobacterial outgrowths are naturally occurring processes in eutrophic aquatic ecosystems. Furthermore, as a result of climate change and anthropogenic pollution, cyanobacteria harmful algal blooms (CyanoHABs) are expanding worldwide. CyanoHABs are considered a threat to human health and environment due to the production of potent toxic substances, but at the same time, valuable products can be obtained from these microorganisms. The main objective of this study was to test straightforward and cost-effective methods to reduce the toxin content of cyanobacterial biomass for the exploitation of this important biological resource. To carry out this study, lyophilized or hydrated biomass from microcystin-LR (MC-LR) producing Microcystis aeruginosa and cylindrospermopsin (CYN) producing Chrysosporum ovalisporum strains were subjected to the following treatments: (1) thermal (50 °C); (2) ultraviolet (UV) radiation; (3) ozone; and (4) sunlight, for periods varying between 2 and 12 h. MC-LR and CYN concentrations were quantified by LC-MS and compared between experimental groups. The results show a significant reduction in the amount of MC-LR in M. aeruginosa biomass (lyophilized and hydrated) exposed to sunlight. Since no other treatment reduced MC-LR in M. aeruginosa biomass, this molecule was demonstrated to be very stable. Regarding CYN, the concentration of this toxin in C. ovalisporum biomass was significantly reduced with the exposure to UV radiation, to approximately 51% of the initial concentration after 2 h of exposure; 86% reduction after 5 h of exposure; and 77% reduction after 12 h of exposure. Overall, this study demonstrates that the toxicity of cyanobacterial biomass can be reduced by employing environmentally friendly and cost-effective treatments with sunlight and UV radiation.
- Applications of brain wave classification for controlling an intelligent wheelchairPublication . Avelar, Maria Carolina; Almeida, Patricia; Faria, Brígida Mónica; Reis, Luís PauloThe independence and autonomy of both elderly and disabled people have been a growing concern in today’s society. Therefore, wheelchairs have proven to be fundamental for the movement of these people with physical disabilities in the lower limbs, paralysis, or other type of restrictive diseases. Various adapted sensors can be employed in order to facilitate the wheelchair’s driving experience. This work develops the proof concept of a brain–computer interface (BCI), whose ultimate final goal will be to control an intelligent wheelchair. An event-related (de)synchronization neuro-mechanism will be used, since it corresponds to a synchronization, or desynchronization, in the mu and beta brain rhythms, during the execution, preparation, or imagination of motor actions. Two datasets were used for algorithm development: one from the IV competition of BCIs (A), acquired through twenty-two Ag/AgCl electrodes and encompassing motor imagery of the right and left hands, and feet; and the other (B) was obtained in the laboratory using an Emotiv EPOC headset, also with the same motor imaginary. Regarding feature extraction, several approaches were tested: namely, two versions of the signal’s power spectral density, followed by a filter bank version; the use of respective frequency coefficients; and, finally, two versions of the known method filter bank common spatial pattern (FBCSP). Concerning the results from the second version of FBCSP, dataset A presented an F1-score of 0.797 and a rather low false positive rate of 0.150. Moreover, the correspondent average kappa score reached the value of 0.693, which is in the same order of magnitude as 0.57, obtained by the competition. Regarding dataset B, the average value of the F1-score was 0.651, followed by a kappa score of 0.447, and a false positive rate of 0.471. However, it should be noted that some subjects from this dataset presented F1-scores of 0.747 and 0.911, suggesting that the movement imagery (MI) aptness of different users may influence their performance. In conclusion, it is possible to obtain promising results, using an architecture for a real-time application.
- Contributions for the validation of the European Portuguese version of the vascular quality of life-6 questionnaire for Peripheral Artery diseasePublication . Oliveira, Rafaela; Pedras, Susana; Pimenta, Rui; Silva, IvonePeripheral arterial disease (PAD) is an occlusive atherosclerotic disease of the arteries of the extremities of the body that affects more than 230 million people worldwide. The most common symptom is intermittent claudication, described as leg pain which occurs mainly while walking. The symptoms impair the ambulation and functional capacity of patients, leading to loss of mobility, disease deterioration, increased risk of other cardiovascu-lar diseases, and lower quality of life (QoL). Therefore, the aim of this study was to perform a cross-cultural adaptation and validation of the VascuQol-6 questionnaire for the Portuguese population to obtain a quick, sensitive, and easy-to-use way to assess the QoL of Portuguese patients diagnosed with PAD. The Vascular Quality of Life-6 Questionnaire (VascuQoL-6) was adapted and translated into European Portuguese using standard validation methodology, including 115 patients with a mean age of 64.67 (7.23) years, with PAD with IC stable for more than three months; and ABI < 0.9 at rest. VascuQoL-6, SF-36, International Physical Activity Questionnaire (IPAQ), and the PAD Knowledge Questionnaire (PADKQ) were used. Reliability, con-struct validity analysis through convergent and discriminant validity, known-group validity, and responsiveness analysis were tested. The Cronbach’s alpha was 0.64 and the average inter-item correlation was 0.27, indicating acceptable internal consistency. VascuQoL-6 was positively associated with SF-36 Physical Component Summary and Mental Component Summary scores (r = 0.64, p < 0.01 and r = 0.42, p < 0.01, re-spectively). In turn, there was no significant correlation between VascuQoL-6 scores and the PADKQ or IPAQ. A statistically significant difference between groups according to IC severity [F(2.47) = 8.35, p < 0.001] was found. A paired samples t-test showed differences between VascuQol-6 scores before a walking program (M = 15.65, SD = 3.09), and after a walking program (M = 17.41, SD = 2.71), t(67) = 3.94, p ≤ 0.001. The VascuQoL-6 is a six-item instrument to assess the QoL associated with PAD with good psychometric properties, convergent and dis-criminant validity with SF-36, PADKQ and IPAQ. The instrument proved to have known group validity and responsiveness.