Portail HAL UHA (Université de Haute-Alsace)
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MXenes as Electrocatalysts for Energy Conversion Applications: Advances and Prospects
No full textInternational audienceHydrogen as a potential future energy source provides a number of benefits in terms of sustainability, high energy density, and zero emissions. The production of hydrogen via water splitting is regarded as the cleanest and sustainable process. In contrast, fossil fuel combustion causes significant environmental problems through the production and release of secondary gases such as NO x , SO 2 , and CO 2 . It is vital to focus on reducing these harmful gases. CO 2 , a major pollutant produced by the combustion of fossil fuels and various human activities, plays a central role in the greenhouse effect and contributes to global warming. It is therefore imperative to actively eliminate and mitigate CO 2 levels to preserve the global environment. MXenes and MXene‐based catalysts exhibit both outstanding hydrogen evolution reaction (HER) performance and CO 2 reduction. In this review, recent progress is systematically examined and discussed in the preparation and utilization of MXenes as catalysts for HER and carbon dioxide reduction reaction (CO 2 RR). The discussion begins with a concise overview of the fabrication and characteristics of MXenes, followed by a comprehensive exploration of their efficacy as catalysts for HER and CO 2 RR
Auditor Perception of Corporate Excess Cash Holdings: The French Evidence
No full textInternational audienceThe audit literature highlights the influence of the context on the relationship between excess cash and audit fees (Gleason et al., 2017; Kuo et al., 2022). We study this relationship in the French context, which presents several specificities regarding corporate governance and audit regulation. The empirical study conducted on an initial sample of 1411 observations of French-listed firms over the period [2008- 2018] shows that excess cash is associated with lower audit fees. However, this relationship no longer holds for firms whose accounting and financial decisions may seem contradictory to holding excess cash. These results complement previous research and show an intermediate situation between those described in the American and Chinese contexts. French auditors generally look favorably on excess cash, but their perception can change, charging extra fees in circumstances where holding excess cash may seem suboptimal
NIR photopolymerization self-writing process for fiber-to fiber and VCSEL-to-fiber single mode coupling
No full textNational audienceLow-loss coupling of VCSELs (vertical-cavity surface-emitting lasers) to optical fibres is a key issue for increasing theiruse in optical communications and instrumentation systems. However, tolerances on angular tilts and lateral misalignments are tight, particularly in the case of single mode devices. To address this challenge, a new fabrication method based on near-infrared single-mode self-writing (NIR-SM-SWW) of a polymer waveguide was developed and tested for the coupling of two single mode fibers at 850 nm (Thorlabs 780-HP) with a mode field diameter close to that of 850 nm single mode VCSEL. The specificity of our method is to use a writing wavelength identical to that designed for single mode propagation in the fibers, leading to a single step photopolymerization process that will be directly transferable to 850 nm VCSEL-to-fiber coupling. First results show coupling losses at 850 nm as low as 0.86 dB for a distance between the fibers of 100 μm
Auditor Perception of Corporate Excess Cash Holdings: The French Evidence
No full textInternational audienceThe audit literature highlights the influence of the context on the relationship between excess cash andaudit fees (Gleason et al., 2017; Kuo et al., 2022). We study this relationship in the French context,which presents several specificities regarding corporate governance and audit regulation. The empiricalstudy conducted on an initial sample of 1411 observations of French-listed firms over the period [2008-2018] shows that excess cash is associated with lower audit fees. However, this relationship no longerholds for firms whose accounting and financial decisions may seem contradictory to holding excesscash. These results complement previous research and show an intermediate situation between thosedescribed in the American and Chinese contexts. French auditors generally look favorably on excesscash, but their perception can change, charging extra fees in circumstances where holding excess cashmay seem suboptimal
Pérovskite à base de manganèse pour l’oxydation catalytique de polluants (CO, COV...)
No full textInternational audienc
Formation of iron-rich phyllosilicates in the FeO–SiO 2 –H 2 O system during hydrothermal synthesis as a function of pH
No full textInternational audienceThe formation of iron-rich phyllosilicates can occur at different natural or engineered settings. In this study, the influence of pH in the hydrothermal synthesis of iron-rich phyllosilicates was investigated in the pH range 8.50–12.10 after the ageing of the precursor. The synthesized samples were characterized by powder X-ray diffraction, Raman and Mössbauer spectroscopies and transmission electron microscopy. Three domains of pH were identified, and these correlated with silica availability and its speciation in the solution. The formation of 1:1-type Fe III /Fe II phyllosilicate was observed between pH 9.67 and 10.75. Above pH 10.75, two types of phyllosilicate-like mineral phases were observed. In addition to 1:1-type Fe III /Fe II phyllosilicate, 2:1-type Fe III /Fe II phyllosilicate was observed. Below pH 9.67, mainly amorphous silica and iron oxides were observed. The findings show that pH governed the crystallinity and nature of the obtained phyllosilicate-like phases
Building a cm² scale CVD graphene-based gas sensor: modelling the kinetic with a three-site adsorption/desorption Langmuir model.
No full textInternational audienceAbstract In this article, we aim to develop and study a highly sensitive and selective cm² scale graphene-based gas sensor. We present the technology used to fabricate sensors which integrate monolayer CVD graphene: photolithography and transfer of layers. Characterization techniques (optical microscopy, AFM, micro-Raman spectroscopy, transport electrical measurements) ensure a diagnosis of graphene ribbons and allow good reproducibility of technological processes. We present the results of gas characterizations after a 200 ppm NO2 exposure. We propose a novel approach for the modelling of the sensor response with a three-site adsorption/desorption Langmuir model. This innovative way of modelling the sensor response should provide a better understanding of the sensor’s kinetic and help to overcome the long response time observed with graphene gas sensors.
Le duty of care des entreprises et la dynamique du standard of care : vers un devoir vigilance renforcée
No full textMit Fürsorge auf die ökologische Krise reagieren. Vor dem Hintergrund des durch menschliche Aktivitäten verursachten ökologischen Ungleichgewichts verpflichtet die dreifache ökologische Krise – Klimawandel, Verlust der biologischen Vielfalt und Umweltverschmutzung – jeden Einzelnen zum Schutz der Umwelt. Mehrere internationale Abkommen und nationale Gesetze erkennen Umweltgrundsätze und -rechte an, wie beispielsweise das Recht auf eine gesunde Umwelt und den Grundsatz der Umweltverantwortung, der den Schutz der Umwelt und die Vermeidung von Schäden beinhaltet. Trotz der Versuche, bestimmte Gesetze aufzuheben, gibt es einen allgemeinen Trend unter den Staaten, dem Umweltschutz in ihren Rechtssystemen Vorrang einzuräumen. Trotz der beträchtlichen Zunahme von Texten, die zu einer „Umweltrechtsstaatlichkeit” beitragen, wird ihre Wirksamkeit von denjenigen, die in diesem Bereich tätig sind, auf die Probe gestellt. Das im Gewohnheitsrecht verankerte Konzept der Sorgfaltspflicht bietet eine mögliche Lösung für die Herausforderungen, die mit der Gewährleistung der Wirksamkeit von Umweltgesetzen und der Rechenschaftspflicht von Unternehmen verbunden sind. Neue Texte und Rechtsprechung zu diesem Thema deuten auf einen Trend zur Bildung eines globalen Standards der Sorgfaltspflicht hin, d. h. eines allgemein erhöhten Maßes an Wachsamkeit.(Übersetzt mit DeepL.com)Responding to the ecological crisis through care. In a context of ecological imbalance caused by human activities, the triple ecological crisis of climate change, biodiversity loss and pollution imposes a duty on everyone to protect the environment. Several international agreements and national laws recognise environmental principles and rights, such as the right to a healthy environment, and the principle of environmental responsibility, which involves protecting the environment and avoiding harm. Despite attempts to dismantle certain legislation, there is a general trend among states to prioritise environmental protection within their legal systems. However, despite the considerable increase in texts contributing to an 'environmental rule of law', their effectiveness is being tested by those working in the field. The concept of care, rooted in common law, offers a potential solution to the challenges of ensuring the effectiveness of environmental legislation and holding corporations accountable. New texts and case law on the subject suggest a trend towards the formation of a global standard of care, i.e. a general heightened level of vigilance.Répondre à la crise écologique par le care. Dans un contexte de bouleversement des équilibres écologiques causé par les activités humaines , la triple crise écologique – dérèglement climatique, perte de biodiversité et pollution – impose à toute personne un devoir de protection de l’environnement. Plusieurs accords internationaux et législations nationales reconnaissent des principes et droits environnementaux tels que le droit à un environnement sain ou le principe d’une responsabilité environnementale consistant à protéger l’environnement ou ne pas y porter atteinte . Malgré les intentions de revenir en arrière sur certaines législations, il existe un mouvement général des Etats à placer le devoir de protection de l’environnement au plus haut niveau de leur hiérarchie des normes . En dépit de l’accroissement considérable de textes participant d’un « état de droit environnemental » , leur effectivité résistent à l’épreuve des acteurs du terrain. La notion de care issue de la common law constitue un élément de réponse aux enjeux d’effectivité des normes environnementales et de responsabilisation des entreprises. Les nouveaux textes les concernant et la jurisprudence laissent entrevoir une dynamique de formation d’un standard du care global, c’est-à-dire d’une une norme générale de vigilance renforcée
La Belle Polonaise ou les événements de Pologne au prisme du roman français de la fin du XVIIIe siècle (Marat, Louvet)
No full textInternational audienc
Gaseous and particulate emissions from the combustion of wood pellets
No full textInternational audienceWood combustion results in gaseous emissions (mainly CO, CO2, NO, NO2, and low concentrations of SOx) which are harmful to humans and partly responsible for climate change. Such combustion also results in emissions of fine and ultrafine particles which are also harmful to humans. The aim of the present study is to analyze the gaseous and particulate emissions occurring during the combustion of wood pellets in a drop tube furnace. This device allows reproducing combustion experiments in domestic pellet furnaces, the pellet falling from the top of the drop tube furnace to the reaction zone in approximately 1 s, thus leading to high heating rates. The temperature of the reaction zone can be adjusted, here between 500 and 900 °C. Gas analyzers and an Electrical Low Pressure Impactor complete the experimental setup to continuously measure the gaseous and particulate emissions. The pellet mass is also continuously measured during the combustion experiment. From these different experimental conditions that leading to minimal emissions are determined, which reduce the risks to humans and the environment. The present study is complementary to that carried out on the combustion of a wood pellet but under low heating rates, [1]. Comparisons of the results obtained under high and low heating rates will be presented