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Synthesis, Characterization, and Biological Evaluation of Iron(III)- N -Heterocyclic Carbene Complexes as Photosensitizers for Photodynamic Therapy and Chemotherapeutics against Cancer
No full textInternational audiencePhotodynamic therapy (PDT) is a promising strategy for cancer treatment, yet the reliance on rare, expensive, and potentially toxic heavy metals limits the practical application of many current photosensitizers. In this study, we synthesized and evaluated a series of iron(III)-N-heterocyclic carbene (Fe(III)-NHC) complexes (1–7) bearing diverse substituents to explore their potential as cost-effective alternatives for cancer therapy. While none of the complexes exhibited significant singlet oxygen generation under light excitation, several (particularly complexes 1, 2, 3, and 7) showed strong cytotoxicity toward cancer cells even in the absence of photodynamic activation. Structure–activity analysis revealed that hydrophobic or moderately electron-donating groups enhanced cellular uptake and bioactivity, while polar or bulky substituents reduced efficacy of cellular uptake, as confirmed by ICP-MS and confocal fluorescence microscopy. Further biological studies suggested that the cytotoxic effects of these compounds may stem from mitochondrial damage, potentially caused by disruption of mitochondrial membrane potential through iron-mediated redox processes. These findings highlight the promise of Fe(III)-NHC complexes as potential chemotherapeutic agents and underscore the importance of rational ligand design in modulating their biological activity
Country scale assessments of coastal fish communities and drivers for sustainable socio-ecosystem management
No full textInternational audienceTropical coastal marine ecosystems, such as coral reefs, mangroves, and seagrass beds, harbor a significant portion of marine biodiversity and productivity, providing essential ecosystem services to human societies, including food and fisheries resources. However, global changes are causing rapid degradation of these ecosystems, resulting in the loss of ecological functions, habitats, and resources, which threaten both ecosystems and human societies. Successful examples of localized ecosystem and resource management exist, but generalizing these at larger, country and regional scales, which are relevant to strategic decisions, remains challenging. Identifying appropriate management measures is often difficult because ecosystem resilience is driven by various ecological processes that can be disrupted by a multitude of environmental stressors, including local pressures from fishing, habitat degradation and destruction, and global climate change, whose prevalence can vary across sites and species. We use a country-scale collaborative science approach to quantify long-term changes in fish communities, assess the efficiency of current management, and identify critical stress thresholds for sustainable management in the broad and biodiverse coastal system of New Caledonia. Our analyses characterize the distribution, composition, and abundance-biomass trajectories of key fish communities at various scales around the archipelago to shed light on local management successes and failures, as well as the mechanisms underlying resilience, to advise management decisions. Carried out in close collaboration with local communities, this work contributes to the development of sustainable management and conservation plans for New Caledonia’s exceptional coastal marine ecosystems and fish resources, which are listed as a UNESCO World Heritage site
Realistic Modeling of Photovoltaic Solar Cell: A Simple and Accurate Two‐Diode Model
No full textInternational audienceABSTRACT Photovoltaic modules are determinant in producing sustainable energy with a reduced environmental impact. This article explores the progressive modeling of photovoltaic modules, from the straightforward but approximate one‐diode model to the more accurate but more complex two‐diode model. It focuses on the parameters to be considered and the judicious choice of hypotheses to obtain electrical behavior close to that obtained experimentally for different environmental conditions. A reverse coupled saturation current and the Newton−Raphson method are both used for theoretical calculation and the simulation, respectively. Simulations show that the root mean square error (RMSE) on the I–V curves is reduced by 11.2% for irradiance of 1000 W/m² and by 28.3% on the P–V curves at 60°C. Additionally, the parallel resistance estimated with the two‐diode model is lower than with the single‐diode model (310 to 110.8 Ω), indicating a better consideration of leakage currents. Although the computation time is increased by around 40%, the improvement in accuracy justifies this added complexity. In conclusion, the study confirms the relevance of the two‐diode model for a more realistic representation of photovoltaic module performance under various environmental conditions
In-situ observations for analyzing urban overheating in tropical island contexts: A case study from Reunion Island
No full textInternational audienceClimate change poses escalating risks to urban populations, particularly in tropical regions where vulnerability is projected to rise, as highlighted in the IPCC's Sixth Assessment Report. Among these risks, the Urban Heat Island (UHI) effect—marked by elevated temperatures in urban areas relative to their rural surroundings—is amplified by urban densification. However, research on UHIs and their impacts remains limited in tropical settings, especially on small islands where unique climatic and geographic conditions exacerbate the issue.This study delivers the first detailed analysis of urban overheating impacts at the district scale on Reunion Island. Using a network of low-tech environmental sensors, we conducted high-resolution in situ measurements of key atmospheric variables, including air temperature, relative humidity, wind speed, and solar radiation. These microscale observations allowed for a precise assessment of the spatial variability of heat within the urban fabric and enabled the calculation of thermal comfort indices to fully capture the effects of urban overheating.Preliminary results show that despite its modest population of approximately 850,000, Reunion Island exhibits a significant UHI effect, with temperature differentials exceeding 2°C between urban and rural areas. Furthermore, shading plays a critical role in mitigating heat stress, as evidenced by differences in the Universal Thermal Climate Index of up to 5°C between shaded and unshaded zones within the same neighborhood. These findings highlight the importance of incorporating shading, vegetation, and optimized urban morphology to enhance outdoor thermal comfort in tropical climates.By demonstrating the value of in situ environmental observations in understanding urban overheating challenges, this study provides actionable insights for policymakers and urban planners. It underscores the importance of targeted mitigation strategies, such as increasing vegetation coverage and promoting natural ventilation, to reduce the impacts of UHIs in tropical island urban environments
The invaded range of the tree fern Sphaeropteris cooperi is predicted to shrink in two southern hemisphere biodiversity hotspots
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/613788/) * Autres projets (id;sigle;titre): ;;(FRA) Oil BodiEs for INNovative food products: from plant seed processing to digestive fate//International audienceBiological invasions are increasing globally, with species demonstrating differing responses to climate change in their native and invaded ranges. Investigating how alien species respond to climate change is important for planning management interventions. This study considered how the distribution of Sphaeropteris cooperi (Hook. ex F.Muell.) R.M.Tryon, a widely cultivated invasive tree fern with a broad climatic tolerance, could alter under climate change in two invaded southern hemisphere biodiversity hotspots: South Africa's Garden Route and La Réunion Island, Mascarene Archipelago. To determine the distributional changes of S. cooperi under future climate change scenarios, its niche dynamics were assessed in its native range (Australia) and two invaded southern hemisphere ranges using Schoener's statistic for niche overlap and principal component analyses. An ensemble modelling approach was used to predict the potential distribution of S. cooperi under future (2041–2070 and 2071–2100) carbon emission scenarios (SSP1-2.6 and SSP 5–8.5) using five global climate models. The results suggest that S. cooperi demonstrates some climatic niche overlap (17.6 %) between the Garden Route and its native range (Australia), but less overlap (3.7 %) was found between La Réunion Island and Australia. On La Réunion Island, little niche overlap together with niche expansion suggests that S. cooperi occupies niches not occupied in its native range, and that niche conservatism does not hold true for this location. Thus, under current climatic conditions, future spread may be anticipated in both the Garden Route and La Réunion Island. However, climatic conditions are shifting making it important to consider climate change when predicting how the range of this invader may change in the future. Species distribution models revealed that for both biodiversity hotspots, regardless of climatic scenario or the time frame considered, the range of S. cooperi is predicted to shrink, although the degree of decline is expected to vary with time and climate scenario
Morphological and biological characteristics of Badamia exclamationis (Fabricius) (Lepidoptera: Hesperiidae) damaging on Hiptage benghalensis (Malpighiaceae) in Viet Nam
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/613562/)International audienceSome morphological and biological characteristics of Badamia exclamationis (Fabricius) were studied on the plant Hiptage benghalensis (L.) Kurz under laboratory and net house conditions at the Department of Plant Protection, College of Agriculture, Can Tho University. Female adults of B. exclamationis began laying eggs 3–4 days after emergence, with an average incubation period of 3.06 days. Larval stage consists of 5 instars with development times of 1.29; 2.00; 1.97; 2.74 and 5.77 days, respectively. The pupal stage lasted for an average of 7.43 days, completing the life cycle in 21–37 days (average 27.46 days). The egg hatching rate was 70%, and the survival rate of the post-egg stages was over 85%. A female laid an average of 104.8 eggs. Damages caused by larvae of B. exclamationis on leaves of H. benghalensis were describeded in details
Freeing transdisciplinarity from the project straightjacket: Reframing the problem
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/613167/)International audienceConfronting systemic problems in ecological and socio-technical systems requires transcending traditional reductionist approaches and disciplinary silos. Transdisciplinarity (TD) is frequently proposed and embraced as a way of organizing science so that it is better suited to approach wicked problems, and science funders are increasingly interested in investing in large scale integrated initiatives. Achieving effective coordination and cooperation in these types of initiatives, however, has proved notoriously challenging in practice. Here we put the focus on how TD initiatives are organized. We argue that the notions of “project” and “project management” create organizational and behavioral frameworks that are inadequate and ultimately deleterious for this kind of work. In fact, the project - understood as an institution - has permeated into many aspects of society, not just science, in a process that scholars have named “projectification”. As a deliberate reframing exercise, we explore alternative logics of organizing transdisciplinary work. We offer four major examples from different domains, which we think can help imagine better ways for 'governing transdisciplinarity'. Transdisciplinary initiatives can contain projects, but not be projects, and, importantly, the need for these projects should emerge from transdisciplinary processes. Conceiving transdisciplinary initiatives as something other than projects would change how we run the initiatives themselves, but this cannot happen in a context where so much in science is organized around projects
Rapid analysis of starch, sugar, and amylose in fresh yam tubers and boiled yam texture using near-infrared hyperspectral imaging and chemometrics
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/612497/) * Autres projets (id;sigle;titre): ;RTBfoods project;(FRA) Breeding RTB Products for End User Preferences// ;;(NGA) African Yam//International audienceThe study investigated the use of the near-infrared hyperspectral imaging (NIR-HSI) technique (932 – 1721 nm) to rapidly evaluate the starch, sugar, and amylose content of fresh, intact yam tubers and the textural qualities of boiled yam. These quality characteristics often influence consumers' and farmers' acceptance of new yam varieties. Traditional methods for their determination are expensive, time-consuming, and sometimes subjective. The NIR-HSI system combined with three Effective Wavelengths (EWs) selection algorithms, including Successive Projections Algorithms (SPA), Competitive Adaptive Reweighted Sampling (CARS), and Boruta Algorithm (BA), was used to extract the important spectral features. The PLSR-SPA-CARS gave the best prediction models in most cases, with a coefficient of determination in prediction (R2pre) of 0.952 for starch, 0.935 for sugar, and 0.978 for amylose content, respectively. The spatial distribution of starch, sugar, and amylose was visualized using the optimized PLSR model. Additionally, PLSR-SNV-SG (Standard Normal Variate and Savitzsky-Golay) showed the best R2 pred of 0.846 for peak force (hardness) and 0.538 for the area under the curve (chewiness) of boiled yam. This study has demonstrated the potential of NIR-HSI techniques to rapidly predict the quality of fresh yam and its boiled food product
Axe : Sémiotique des médias Titre : Pollution sémio narrative des rédactions par le sponsoring en TV
No full textScience du langage/Sémiotique de la communicationThis article is a tribute to the demarcation of editorial statements from advertising statements in TV production in Cameroon. The presentation demonstrates that certain TV newsrooms with private capital make a voluntary discursive amalgamation between writing and advertising in context. This means, on the one hand, that there is a gradual decline in the vigilance of the regulatory framework and on the other hand, that audiovisual editorial staff are gradually establishing totally libertine habits. At the same time, regulatory authorities are distinguished by preferences, with a particular devotion to controlling more, the discourse on political governance, to the detriment of a holistic regulation of television discourse. The article therefore sounds like a plea, so that better attention be paid to all discursive genres in television. Certainly, the ambient precariousness is not necessarily adjuvant to compliant practices; however, there is an urgent need to ensure that the gap does not continue to prevail over the norm. We can then envisage as a pragmatic follow-up to this publication, a previously unexpected awakening of the actors, the national advertising council and the national communication council. As much as they each still have an object.Le présent article est un tribut, pour la démarcation des énoncés de rédaction vis-à-vis des énoncés de publicité en production TV au Cameroun. L'exposé fait la démonstration que, certaines rédactions TV à capitaux privés, font un amalgame discursif volontaire, entre rédaction et publicité en contexte. C'est dire d'une part, qu'il existe un recul progressif de la vigilance du cadre réglementaire et d'autre part, que les rédactions de l'audiovisuel établissent graduellement, des accoutumances totalement libertines. En même temps, les instances de régulation s'illustrent par des préférences, avec une dévotion particulière à contrôler plus, le discours sur la gouvernance politique, au détriment d'une régulation holistique du discours de télévision. L' article sonne donc comme un plaidoyer, afin qu'une meilleure attention soit prêtée à tous les genres discursifs en télévision. Certes, la précarité ambiante n'est pas forcément adjuvante à des pratiques conformes néanmoins, il y a urgence pour que l'écart ne continue pas de prévaloir sur la norme. L'on peut alors envisager comme suite pragmatique à cette publication, un réveil jadis inespéré des acteurs, conseil national de la publicité et conseil national de la communication. Autant qu'ils ont encore chacun, un objet.</div
Geomorphology of the Okavango – Makgadikgadi system: from alluvial fan deposition to erosion
No full textInternational audienceThe morphology of the Okavango Delta alluvial fan results from a combination between local and regional driversincluding tectonics, sedimentation, hydrology and climate. While such alluvial fans are generally considered asdepositional objects, storing more and more sediment as time passes, the recent evolution of the Okavango Deltais more complex. While sediment from the Angola plateau and the northern Kalahari dune fields is still brought tothe alluvial fan, part of the latest is affected by erosion. Indeed, the Quaternary disappearance of the Deceptionand Makgadikgadi lakes, as well as the drying of the climate lowered the base level of the Okavango – Botetisystem. Our observations show that regressive erosion affects the whole river system, from the Makgadikgadipans to the Angola plateau. This mechanism superposes to the tectonic northeastward tilting of the Delta thatdiverts some water flux toward the Selinda-Lynianti-Zambezi system. The combination of these two mechanismsshould have major impacts on the future of the Delta. The regressive erosion may connect the alkalinegroundwater aquifers systems to the surface leading to potentially drastic environmental changes; thenortheastward tilt of the fan will result in the loss of endoreism and the diversion of a large part of the watertoward the Zambezi drainage