Espectroscopia óptica avançada de novos materiais para concentradores solares luminescentes

The transition from the current energy matrix towards an environmentally friendly and a ordable energy sources is a crucial challenge of the 21st century. Fully energetically sustainable architecture is a strategic focus in this e ort, through the realisation of so-called net-zero energy buildings. This implies an increase in the use of renewable resources, such as the wind, tides and the sun. Hence, new technologies that integrate solar-harvesting devices into existing and newly constructed buildings are of growing relevance. Luminescent solar concentrators consist of a transparent matrix doped or coated with active optical centres that absorb the incident solar radiation, which is reemitted at a speci c wavelength and transferred by total internal re ection to the edges, where photovoltaic cells are located. This con guration enables photovoltaic devices to be embedded in building facades or windows, allowing them to be transformed into energy harvesting units. Challenges for the luminescent species in luminescent solar concentrators include the use of sustainable, natural-based organic molecules. In this scope, semitransparent amine-functionalized organic{inorganic hybrids (ureasils) incorporating two di erent natural-based organic dyes, chlorophyll and enhanced uorescent protein (eGFP), were synthesised and processed as thin lms and monoliths. The natural dyes' and organic-inorganic hybrid's excited state dynamics were studied and characterised { the absorption bands of chlorophyll a and eGFP were identi ed, as well as their characteristic emission in the red/NIR (600-750 nm) and visible (450-600 nm) spectral regions, respectively. The emission properties were further quanti ed through absolute emission quantum yield measurements, with the maximum values measured for the eGFP-doped di-ureasil hybrid (0:33 0:03) being two times higher than the maximum value found for the chlorophyll-doped hybrid samples (0:15 0:02). Fluorescent lifetime analysis was also performed resorting to two di erent techniques: time-correlated single photon counting and spectrally-resolved streak imaging, yielding uorescent emission lifetimes of 5 ns for chlorophyll and 2-3 ns for enhanced green uorescent protein, in solution and when incorporated into the hybrid hosts. Further analysis was carried out by tting a two exponential decay model to the uorescent decay curves of the for the green uorescent protein samples, considering that two distinct electronic states are responsible for the absorption around 488 nm and the emission at 510 nm. Based on the intriguing photoluminescent features of the dye-based samples, two prototypes of luminescent solar concentrators were fabricated and optically characterised. In particular, a liquid planar luminescent solar concentrator based on a glass container lled with eGFP dispersed in an aqueous solution and a eGFPdoped di-ureasil hybrid bulk planar luminescent solar concentrator. The devices were coupled to a silicon-based commercial PV device, revealing maximum optical conversion e ciencies of 2:99 0:01% (liquid) and 3:70 0:06% (bulk), illustrating the potential of this approach for the development of nature-based luminescent solar concentrators, meeting the requirements of reliable, sustainable and competitive energy systems.A transição da matriz energética atual para fontes de energia competitivas de baixo impacto ambiental é uma problemática central no século XXI. A arquitetura energeticamente sustentável é um ponto estratégico nesse esforço, através da realização dos chamados edifícios de energia zero. Por defenição, estes edifícios fazem uso de sistemas de produção de energia renovável local, como por exemplo a fotovoltaica, para satisfazer as suas necessidades energéticas. Assim, novas tecnologias que integrem dispositivos de coleção de energia solar em edifícios existentes ou recémconstruídos são de crescente relevância. Os concentradores solares luminescentes são dispositivos compostos por uma matriz transparente com centros óticos ativos incorporados. Estes absorbem a radiação incidente, que é posteriormente reemitida com um comprimento de onda específico e transportada por reflexão interna total até à célula fotovoltaica localizada nas extremidades da matriz. Esta configuração permite a produção de dispositivos fotovoltaicos incorporados em fachadas de edifícios e janelas, permitindo que estes sejam transformados em unidades de produção de energia. Atualmente, um dos desafios na áreas dos concentradores solares luminescentes é a incorporação de moléculas orgânicas naturais como centros óticos. Neste âmbito, foram fabricados e processados híbridos orgânico-inorgânicos semitransparentes, denominados por ureiasils, modificados por dois corantes orgânicos naturais, clorofila e proteína verde fluorescente (eGFP). A dinâmica entre os estados excitados dos corantes naturais e da matriz híbrida foi estudada e caracterizada - foram identifícadas as bandas de absorção da clorofila a e da eGFP, assim como a sua emissão característica no vermelho/infravermelho próximo (600-750 nm) e na região do visível (450-600 nm), respetivamente. As propriedades de emissão foram quantificadas através de medidas de rendimento quântico absoluto, registando-se um valor máximo para o híbrido com eGFP incorporada (0,33+/-0,03) duas vezes superior ao encontrado para as matrizes híbridas dopadas com clorofila (0,15+/-0,02). Foram também analisados os tempos de vida dos emissão dos estados excitados das várias amostras, tendo sido encontrados valores ~5 ns para a clorofila e ~2-3 ns para a eGFP, em solução ou quando incorporadas nas matrizes híbridas. Procedeu-se ainda a uma análise mais aprofundada no caso das amostras com eGFP, através da aplicação de um modelo bi-exponencial às curvas de decaimento, uma vez que o modelo eletrónico da mesma indica a presença de dois estados excitados distintos responsáveis pela absorção em torno dos 488 nm e emissão a 510 nm. Devido às características fotoluminescentes interessantes das amostras à base de corantes naturais para aplicações em concentradores solares luminescentes, foram fabricados e caracterizados dois protótipos com geometria planar { um concentrador solar luminescente baseado num recipiente de vidro cheio com eGFP em solução aquosa, e um outro concentrador que consistia num monolito da matriz híbrida dopada com eGFP. Os dispositivos foram acoplados a uma célula fotovoltaica comercial de silício, revelando eficiências óticas de conversão máximas de 2; 99+/-0; 01% e 3; 70+/-0; 06%, respetivamente, ilustrando o potencial desta abordagem para o desenvolvimento de sistemas energéticos sustentáveis e competitivos.Mestrado em Engenharia Físic

Goodbye Hartmann trial: a prospective, international, multicenter, observational study on the current use of a surgical procedure developed a century ago

Background: Literature suggests colonic resection and primary anastomosis (RPA) instead of Hartmann's procedure (HP) for the treatment of left-sided colonic emergencies. We aim to evaluate the surgical options globally used to treat patients with acute left-sided colonic emergencies and the factors that leading to the choice of treatment, comparing HP and RPA. Methods: This is a prospective, international, multicenter, observational study registered on ClinicalTrials.gov. A total 1215 patients with left-sided colonic emergencies who required surgery were included from 204 centers during the period of March 1, 2020, to May 31, 2020. with a 1-year follow-up. Results: 564 patients (43.1%) were females. The mean age was 65.9 ± 15.6 years. HP was performed in 697 (57.3%) patients and RPA in 384 (31.6%) cases. Complicated acute diverticulitis was the most common cause of left-sided colonic emergencies (40.2%), followed by colorectal malignancy (36.6%). Severe complications (Clavien-Dindo ≥ 3b) were higher in the HP group (P < 0.001). 30-day mortality was higher in HP patients (13.7%), especially in case of bowel perforation and diffused peritonitis. 1-year follow-up showed no differences on ostomy reversal rate between HP and RPA. (P = 0.127). A backward likelihood logistic regression model showed that RPA was preferred in younger patients, having low ASA score (≤ 3), in case of large bowel obstruction, absence of colonic ischemia, longer time from admission to surgery, operating early at the day working hours, by a surgeon who performed more than 50 colorectal resections. Conclusions: After 100 years since the first Hartmann's procedure, HP remains the most common treatment for left-sided colorectal emergencies. Treatment's choice depends on patient characteristics, the time of surgery and the experience of the surgeon. RPA should be considered as the gold standard for surgery, with HP being an exception

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research