Investigation of photocurrents resulting from a living unicellular algae suspension with quinones over time

International audiencePlants, algae, and some bacteria convert solar energy into chemical energy by using photosynthesis. In light of the current energy environment, many research strategies try to benefit from photosynthesis in order to generate usable photobioelectricity. Among all the strategies developed for transferring electrons from the photosynthetic chain to an outer collecting electrode, we recently implemented a method on a preparative scale (high surface electrode) based on a Chlamydomonas reinhardtii green algae suspension in the presence of exogenous quinones as redox mediators. While giving rise to an interesting performance (10-60 mA cm À2) in the course of one hour, this device appears to cause a slow decrease of the recorded photocurrent. In this paper, we wish to analyze and understand this gradual fall in performance in order to limit this issue in future applications. We thus first show that this kind of degradation could be related to over-irradiation conditions or side-effects of quinones depending on experimental conditions. We therefore built an empirical model involving a kinetic quenching induced by incubation with quinones, which is globally consistent with the experimental data provided by fluorescence measurements achieved after dark incubation of algae in the presence of quinones

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

The global burden of cancer attributable to risk factors, 2010–19: a systematic analysis for the Global Burden of Disease Study 2019

BACKGROUND: Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. METHODS: The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk–outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. FINDINGS: Globally, in 2019, the risk factors included in this analysis accounted for 4·45 million (95% uncertainty interval 4·01–4·94) deaths and 105 million (95·0–116) DALYs for both sexes combined, representing 44·4% (41·3–48·4) of all cancer deaths and 42·0% (39·1–45·6) of all DALYs. There were 2·88 million (2·60–3·18) risk-attributable cancer deaths in males (50·6% [47·8–54·1] of all male cancer deaths) and 1·58 million (1·36–1·84) risk-attributable cancer deaths in females (36·3% [32·5–41·3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20·4% (12·6–28·4) and DALYs by 16·8% (8·8–25·0), with the greatest percentage increase in metabolic risks (34·7% [27·9–42·8] and 33·3% [25·8–42·0]). INTERPRETATION: The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden

Dérivation des électrons photosynthétiques par des quinones sur organisme entier : le cas de Chlamydomonas reinhardtii

Photosynthetic electron derivation on living organism using quinones : the case of Chlamydomonas reinhardtii Nowadays, energy is a major concern to societies and research is focusing on finding new sources of clean and sustainable energy. In this context, photosynthesis may be an appropriate way to meet this objective. Indeed solar light provides the chemical energy required by photosynthetic organisms to maintain their cellular activity. Taking advantage of photosynthesis to produce a photocurrent requires intercepting electrons exchanged in the oxidation/reduction processes occurring along the photosynthetic chain. This is why we consider here an electrochemical device involving a gold electrode able to derivate photosynthetic electrons from a population of Chlamydomonas reinhardtii algae. However photosynthsesis is a multi-speed process and a rate controlling step was identified just before the b6f complex. This is why the strategy of this work aimed at deriving electrons before the b6f cytochrom. This allows to relieve algae from stress under high light conditions. Known as efficient PSII acceptors, quinones were used as exogenous mediators to transfer the electrons from the photosynthetic chain to the electrode surface. Therefore, the resulting photocurrents under illumination, were commented and discussed in order to understand and define the best appropriate experimental conditions for this bio-solar generator. Quinones were shown to induce toxicity on algae. Focus was directed on finding the best chemical structure which would combine good derivation properties and little toxicity.L'énergie est un enjeu crucial pour les sociétés actuelles et le recours à des énergies alternatives est de jour. Or la photosynthèse apparaît comme une piste intéressante et les unités photosynthétiques comme des convertisseurs potentiels sélectionnés par l'Evolution. Lors de la photosynthèse électron poursuit son cheminement le long de la chaîne photosynthétique pour permettre la mise en marche des différents complexes enzymatiques nécessaires au maintien en vie de l'organisme photosynthétique. L'étape cinétiquement limitante de ce transfert électronique se situe en amont du cytochrome b6f. C'est cette limitation qui serait responsable des dommages encourus par les algues sous forte lumière connus sous le nom de photoinhibition. Ainsi pour ne pas compromettre la vie de l'algue unicellulaire Chlamydomonas reinhardtii, la stratégie mise en place durant ces travaux de thèse a été de dériver les électrons d'une manière sélective en amont de l'étape cinétiquement limitante. Pour cela des quinones exogènes ont été utilisées comme accepteurs d'électrons capables d'atteindre la chaîne photosynthétique, de récupérer les électrons et de venir s'oxyder à l'électrode polarisée. Une demi-pile a été mise en place et la stabilité du courant dans le temps étudiée. Une toxicité des quinones a en particulier été mise en évidence et serait responsable de la dégradation des performances du système au cours du temps. Les spectroscopies de fluorescence et d'absorption ont pu fournir des éléments de réponse. Des critères de choix de quinones ont été identifiés et partant de là, de la synthèse organique a été effectuée pour essayer de trouver un compromis entre dérivation et toxicité

Photosynthetic electron derivation on living organism using quinones : the case of Chlamydomonas reinhardtii

L'énergie est un enjeu crucial pour les sociétés actuelles et le recours à des énergies alternatives est de jour. Or la photosynthèse apparaît comme une piste intéressante et les unités photosynthétiques comme des convertisseurs potentiels sélectionnés par l'Evolution. Lors de la photosynthèse électron poursuit son cheminement le long de la chaîne photosynthétique pour permettre la mise en marche des différents complexes enzymatiques nécessaires au maintien en vie de l'organisme photosynthétique. L'étape cinétiquement limitante de ce transfert électronique se situe en amont du cytochrome b6f. C'est cette limitation qui serait responsable des dommages encourus par les algues sous forte lumière connus sous le nom de photoinhibition. Ainsi pour ne pas compromettre la vie de l'algue unicellulaire Chlamydomonas reinhardtii, la stratégie mise en place durant ces travaux de thèse a été de dériver les électrons d'une manière sélective en amont de l'étape cinétiquement limitante. Pour cela des quinones exogènes ont été utilisées comme accepteurs d'électrons capables d'atteindre la chaîne photosynthétique, de récupérer les électrons et de venir s'oxyder à l'électrode polarisée. Une demi-pile a été mise en place et la stabilité du courant dans le temps étudiée. Une toxicité des quinones a en particulier été mise en évidence et serait responsable de la dégradation des performances du système au cours du temps. Les spectroscopies de fluorescence et d'absorption ont pu fournir des éléments de réponse. Des critères de choix de quinones ont été identifiés et partant de là, de la synthèse organique a été effectuée pour essayer de trouver un compromis entre dérivation et toxicité.Photosynthetic electron derivation on living organism using quinones : the case of Chlamydomonas reinhardtii Nowadays, energy is a major concern to societies and research is focusing on finding new sources of clean and sustainable energy. In this context, photosynthesis may be an appropriate way to meet this objective. Indeed solar light provides the chemical energy required by photosynthetic organisms to maintain their cellular activity. Taking advantage of photosynthesis to produce a photocurrent requires intercepting electrons exchanged in the oxidation/reduction processes occurring along the photosynthetic chain. This is why we consider here an electrochemical device involving a gold electrode able to derivate photosynthetic electrons from a population of Chlamydomonas reinhardtii algae. However photosynthsesis is a multi-speed process and a rate controlling step was identified just before the b6f complex. This is why the strategy of this work aimed at deriving electrons before the b6f cytochrom. This allows to relieve algae from stress under high light conditions. Known as efficient PSII acceptors, quinones were used as exogenous mediators to transfer the electrons from the photosynthetic chain to the electrode surface. Therefore, the resulting photocurrents under illumination, were commented and discussed in order to understand and define the best appropriate experimental conditions for this bio-solar generator. Quinones were shown to induce toxicity on algae. Focus was directed on finding the best chemical structure which would combine good derivation properties and little toxicity

Users\u27 Evaluation of Rail Systems in Mass Events, Case study in Mecca, Saudi Arabia

Each year during the ninth month of the Muslim lunar calendar, more than 2 million Muslim pilgrims from around the world travel to the Holy City of Mecca in Saudi Arabia for Hajj, an annual religious pilgrimage. A significant milestone in the effort to improve the existing transport system in the Holy City was the introduction of the Southern Masha\u27er Rail Line during the 2010 pilgrimage season. In the first year of operation, the line operated at only 30% of its full capacity before full implementation in the following year, when the line operated at full capacity of 72,000 passengers per hour. Results are presented of a users\u27 survey that aimed to assess the performance of the rail line from the perspective of its users. The analysis revealed that rail users faced longer access, waiting, and egress times compared with regular rail operations standards. However, survey results showed that the majority of pilgrims found these times to be tolerable. Moreover, the majority of users found the rail line and its stations to be of excellent quality and gave positive recommendations for using the rail line in the future. The analysis also produced some interesting observations that may be of relevance to rail operation in similar crowded events. Those observations are highlighted

Finding Adapted Quinones for Harvesting Electrons from Photosynthetic Algae Suspensions

International audienceAmong all the chemical and biotechnological strategies implemented to extract energy from oxygenic photosynthesis, several concern the use of intact photosynthetic organisms (algae, cyanobacteria…). This means rerouting (fully or partially) the electron flow from the photosynthetic chain to an outer collecting electrode thus generating a photocurrent. While diverting photosynthetic electrons from living biological systems is an encouraging approach, this strategy is limited by the need to use an electron shuttle. Redox mediators that are able to interact with an embedded photosynthetic chain are rather scarce. In this respect, exogenous quinones are the most frequently used. Unfortunately, some of them also act as poisoning agents within relatively long timeframes. It thus raises the question of the best quinone. In this work, we use a previously reported electrochemical device to analyze the performance of different quinones. Photocurrents (maximum photocurrent, stability) were measured from suspensions of Chlamydomonas reinhardtii algae/quinones by chronoamperometry and compared to parameters like quinone redox potentials or cytotoxic concentration. From these results, several quinones were synthesized and analyzed in order to find the best compromise between bioelectricity production and toxicity