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Photocatalytic properties of La<sub>2</sub>Ti<sub>2</sub>O<sub>7</sub> synthesized by glycine-assisted sol-gel method and its impact on intestinal and blood-brain barriers
No full textInternational audienceThe La₂Ti₂O₇ photocatalyst, synthesized using a glycine-assisted sol-gel method, demonstrates excellent efficiency in the photodegradation of both anionic dyes, such as Naphthol Green B and Eosin Y, and cationic dyes like Crystal Violet, at a pH of 5.8 under UV irradiation. Kinetic studies reveal that the degradation process follows first-order kinetics, specifically described by the Langmuir-Hinshelwood model. Additionally, this photocatalyst has been successfully utilized for the photoreduction of Cr(VI) to Cr(III). Mott-Schottky analysis of La₂Ti₂O₇ confirms its n-type semiconductor behavior and provides insights into its flat band potential. The conduction and valence band levels were determined experimentally through flat band potential measurements and optical band gap analysis, showing good agreement with theoretical values obtained from the Mulliken electronegativity approach. Furthermore, photocurrent transient response measurements under both UV and solar excitation reveal a higher photocurrent density in the UV spectral region, consistent with the material's absorption characteristics. This suggests the photocatalyst's potential applicability in treating various pollutants, making it a promising candidate for wastewater remediation. For the first time, to the best of our knowledge, the impact of La₂Ti₂O₇ toxicity on the human body was also investigated. Specifically, its effects were studied on the human intestinal barrier and a human in vitro blood-brain barrier model. The results indicate no cytotoxicity at concentrations ranging from 0.1 to 1 μg.mL−1, highlighting its potential as a safe and effective material for environmental and biomedical applications
Electricity-driven selectivity in the photocatalytic oxidation of methane to carbon monoxide with liquid gallium-semiconductor composite
No full textInternational audienceMetal co-catalysts in oxide semiconductors are essential to enhance photocatalytic reaction, but the selectivity is often low due to the conversion of the target molecules as more reactive in comparison with the reagents. Here, we explore the influence of electricity on the activity and selectivity of liquid gallium as a co-catalyst loaded in TiO2 and ZSM-5 supports the photocatalytic oxidation of methane. We first show that the polarization of the photocatalytic chips allows a more efficient wetting of liquid gallium into the semiconductor matrices, which increases the availability of the photogenerated charge carriers for reactions and improves the overall activity of the composites. More importantly, the oxide skin surrounding the spread liquid is found to be charged, resulting in a significant reduction of the CO oxidation. An increase of the CO selectivity from 10 to 80 % upon polarization to 50 V, with a stable photocatalytic activity reaching 0.6 ± 0.01 mmol/g•h, makes the use of electricity quite appealing to tailor liquid metals in catalysis
Entrapment of Lipase from <i>Candida antarctica</i> in a Xerogel for the Production of Biodiesel from Waste Cooking Oil
No full textInternational audienceThe process to synthesize biodiesel is well-developed and optimized to overcome the disadvantages like the competition with agriculture using feedstock, and the problematics in the process. Oils from waste and enzymatic catalysis have proven to be good solutions to these problems. Lipases are currently the most commonly used enzymes in the transesterification of oils; nevertheless, enzymes have a high cost and must be immobilized to offer repetitive reuse. This work focuses on the synthesis and the optimization of the conditions of a xerogel where the lipase from Candida antarctica is immobilized by entrapment. The xerogel synthesized here, a glass-like material, proved to be very effective in maintaining the enzyme on its structure, with an immobilization yield of 96 % and an activity of 5.3 U/mg (free lipase = 12.1 U/mg). By grinding this xerogel, the immobilization yield remained constant (94 %). Nevertheless, grinding the xerogel allowed better diffusion of reagents, and the activity reached 9.7 U/mg. Using this xerogel in biodiesel production had a positive effect on CALB efficiency by increasing the biodiesel yield, 46.1 % against 15.1 % with free CALB. Finally, the catalyst could be reused for five runs without loss of activity.</div
Rheological benefits of biomass fly ash as filler replacement in cement-based materials
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Optimization of the Antibacterial Activity of a Three-Component Essential Oil Mixture from Moroccan Thymus satureioides, Lavandula angustifolia, and Origanum majorana Using a Simplex–Centroid Design
No full textInternational audienceBackground/Objectives: The rise of antibiotic-resistant pathogens has become a global health crisis, necessitating the development of alternative antimicrobial strategies. This study aimed to optimize the antibacterial effects of essential oils (EOs) from Thymus satureioides, Lavandula angustifolia, and Origanum majorana, enhancing their efficacy through optimized mixtures. Methods: This study utilized a simplex–centroid design to optimize the mixture ratios of EOs for maximal antibacterial and antioxidant effectiveness. The chemical profiles of the EOs were analyzed using gas chromatography-mass spectrometry (GC-MS). The antibacterial activity was assessed against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa using minimum inhibitory concentration (MIC) tests, while antioxidant activity was evaluated through DPPH (2,2-diphenyl-1-picrylhydrazyl), and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assays. Results: The optimized essential oil mixtures demonstrated potent antibacterial activity, with MIC values of 0.097% (v/v) for E. coli, 0.058% (v/v) for S. aureus, and 0.250% (v/v) for P. aeruginosa. The mixture ratios achieving these results included 76% T. satureioides, and 24% O. majorana for E. coli, and varying proportions for other strains. Additionally, L. angustifolia essential oil exhibited the strongest antioxidant activity, with IC50 values of 84.36 µg/mL (DPPH), and 139.61 µg/mL (ABTS), surpassing both the other EOs and standard antioxidants like BHT and ascorbic acid in the ABTS assay. Conclusions: The study successfully demonstrates that optimized mixtures of EOs can serve as effective natural antibacterial agents. The findings highlight a novel approach to enhance the applications of essential oils, suggesting their potential use in food preservation and biopharmaceutical formulations. This optimization strategy offers a promising avenue to combat antibiotic resistance and enhance food safety using natural products
When employees matter: How employee resource groups and workforce liberalism jointly spur firms to support Pro-LGBTQ legislation
No full textInternational audienceEmployees are increasingly vocal about and attentive toward their organizations’ social policies and practices. Scholars have identified two main channels through which employees influence responsible business conduct: (1) employee activists proactively shaping corporate decisions and (2) the prevailing worldviews and attitudes of the workforce, which create normative pressure on appropriate corporate behavior. We propose that these two channels interact to produce high levels of employee influence. To assess this hypothesis, we examined corporate support for the Equality Act, a US congressional bill prohibiting discrimination based on sexual orientation and gender identity. Our quantitative analysis shows that firms with both LGBTQ employee resource groups and liberal workforces were more likely to endorse the Equality Act. Qualitative methods then allowed us to pinpoint the underlying mechanisms. Thus, our study expands our understanding of what enables employees to advance responsible business conduct and why firms engage in sociopolitical issues
Nanocaractérisation AFM d’électrodes polymères extrudées dédiées aux batteries lithium-ion
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Improved Energy Storage in Lead-Free Epitaxial Relaxor Ferroelectric Multilayer Nanocapacitors
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pH-Sensitive Cassava Starch/Onion Peel Powder Films as Colorimetric Indicators for Minced Beef Freshness Monitoring
No full textInternational audiencepH-sensitive intelligent films offer a novel strategy for real-time monitoring of food freshness via visible color changes. This study valorizes onion peel powder (OPP), a polyphenol-rich agro-industrial by-product, by incorporating it into cassava starch-based films at three concentrations (1O, 2O, 3O). Increasing OPP content led to significantly higher total phenolic and flavonoid levels, enhancing the films’ antioxidant properties (p < 0.0001). While the films exhibited selective antibacterial effects, pronounced inhibition zones were observed against Pseudomonas aeruginosa and Escherichia coli, two relevant meat spoilage and pathogenic bacteria. The films displayed clear and gradual color shifts from light to dark brown across a wide pH range (1–13), confirming their suitability as pH indicators. When applied as labels in minced beef packaging stored at 4 °C, the films successfully tracked freshness over 13 days. Film color changes were strongly correlated with microbial load and pH variations, accurately flagging spoilage onset. These findings support the potential of cassava starch/OPP films as biodegradable, cost-effective intelligent packaging tools, contributing to food safety, waste reduction, and circular bioeconomy principles. The system provides a practical, non-invasive solution for meat freshness monitoring without requiring instrumentation
Is longer really better? Results of a retrospective real-life cohort study evaluating the benefit of adding a weekly educational session to a traditional 8-week home-based pulmonary rehabilitation programme in people with COPD.
No full textInternational audienceObjectives To evaluate the short-term and long-term benefits of adding a weekly educational session to a traditional 8-week home-based pulmonary rehabilitation (PR) programme in people with chronic obstructive pulmonary disease (COPD). Primary hypothesis was that 8 home-based supervised sessions will be equivalent to 16 home-based supervised sessions at both short- and long-term after PR.Design Retrospective cohort study conducted on prospectively collected real-life data, from January 2010 to December 2021.Setting FormAction Santé, Pérenchies France.Participants Eligible individuals were aged >18 years with a diagnosis of COPD and referred to the home-based PR programme by their respiratory physician. Participants were retrospectively divided into two groups (Gr 1, 8 PR sessions, n=759, and Gr 2, 8 PR sessions+8 educational sessions, n=262).Intervention All participants received an 8-week personalised home PR programme. A subgroup of participants received one additional supervised home session per week, including education and motivational support for daily physical activities and walking.Outcomes Health-related quality of life, dyspnoea, anxiety and depressive symptoms, fatigue and exercise tolerance were assessed at baseline (M0), at the end of PR (M2), and 14 months (M14) after M0.Results Baseline characteristics and assessments were similar between groups with an exception for long-term oxygen therapy (Gr1: 69.8% vs Gr2 53.0%, p<0.001) and noninvasive ventilation (Gr1: 38.6% vs Gr2: 29.8%, p=0.015). At M2 and M14, all the assessments were improved in both groups (p<0.01). At M2, the improvement in health status and exercise tolerance was higher in Gr 2 compared with Gr 1 (p<0.05). From M0 to M14, 90 (11.9%) participants and 29 (11.1%) participants died in Gr 1 and Gr 2, respectively (p=0.794).Conclusion People with COPD benefited, at short and long terms, from both 8 or 16 supervised home-based PR sessions. Once-weekly home-based supervised sessions during 8 weeks, combined with unsupervised physical training sessions and self-management plan for the other health behaviours, might be the best compromise between patients, health professionals and policy makers