Institute for Public Relations

Abstract Background This study aimed to investigate the occurrence, antimicrobial resistance profiles, and genetic characteristics of extended-spectrum beta-lactamase (ESBL)-producing E. coli in wastewater collected in Dakar, Senegal. Methods A total of 48 wastewater samples were collected during both the dry and wet seasons (May–December 2019) and analyzed for E. coli and ESBL-producing E. coli concentrations using TBX agar with and without cefotaxime supplementation. Antimicrobial susceptibility testing (AST) and ESBL confirmation were performed using the Kirby-Bauer disc diffusion method and the double-disk synergy test, and polymerase chain reaction (Endpoint PCR) assays were performed to identify ESBL genes and determine phylogenetic groups. Results All samples (n = 48) carried ESBL-producing strains. The concentrations of ESBL-producing E. coli ranged from 1.36 × 10⁴ to 3.30 × 10⁵ CFU/100 mL, whereas the ratio of ESBL-producing E. coli among the total E. coli population varied between 0.20% and 16.33%. All the 107 isolated ESBL-producing E. coli strains were multidrug resistant (MDR), with 100% resistance to beta-lactams (ampicillin, ticarcillin, cefalotin, cefotaxime, ceftazidime, cefepime, aztreonam) and high resistance rates to non-beta-lactam antibiotics, including ciprofloxacin (77.57%). Notably, no resistance was observed to imipenem. Molecular analysis identified CTX-M-type genes in all isolates, with bla CTX-M-1 group (89.71%) and bla CTX-M-8 group (88.78%) being the most prevalent. The bla CTX-M-15 variant, a subgroup of bla CTX-M-1, was detected in 96.88% of bla CTX-M-1 positive isolates. Additionally, bla TEM (31.77%) and bla OXA-1 (34.57%) were detected, while bla SHV and bla CTX-M-25 were absent. Phylogenetic analysis of 107 isolates revealed a diverse distribution across four phylogroups: A (37.38%), D (22.43%), B1 (14.02%), and B2 (5.67%). The predominance of phylogroup A, often associated with commensal strains, suggests fecal contamination as a primary source. However, the significant presence of phylogroup D, which is linked to extraintestinal infections, raises concerns about the dissemination of potentially pathogenic strains. Conclusion This study highlights the high prevalence of ESBL-producing E. coli in wastewater in Dakar. The detection of MDR strains, particularly those carrying CTX-M-15 and belonging to pathogenic phylogroups, underscores the urgent need for comprehensive surveillance, improved wastewater treatment, and public health interventions to mitigate the spread of antibiotic resistance in Senegal.

Laser cutting is an old and multi-physical process that was quickly adopted by the metallurgical industry. However, this fast industrialisation has had a significant impact on quality control. Several studies have been carried out to characterise and minimise different types of cutting defects. Reviews published between 2008 and 2022 highlight that research often focuses on single-criterion ___quality' approaches, aiming to minimise specific defects such as the Heat-Affected Zone, surface roughness, or kerf geometry. Consequently, efforts have been directed at optimising specific aspects of quality rather than adopting a complete approach. Furthermore, these reviews reveal that cutting quality can be enhanced through the careful selection of laser manufacturing parameters and part parameters. However, while parameters such as material and thickness have been investigated, the influence of part morphology on cutting quality remains underexplored.___ Although some studies have examined the effects of material and thickness, part morphology is often limited to simple segments with varying cutting lengths or angles. While other research has investigated the impact of angle size on cutting quality, no established method exists to systematically determine the influence of each part morphology on cutting quality.______ In response to this gap, the present study proposes to evaluate the criticality of cutting defects, as defined by existing standards, across various part morphologies using a method adapted from Failure Modes, Effects, and Criticality Analysis (FMECA). The objective is to develop a global approach that examines the influence of all morphologies on all types of cutting defects. An industrial application shows that cutting defects, particularly thermal ones, are strongly influenced by morphologies, while thickness affects them irregularly. Improvement priorities target critical defects shaped by both factors. Burrs and adherent slag are critical in angles and arcs, while segments, often used in studies, are less sensitive._________ These observations lead to the definition of design limits. This method offers a detailed analysis of the influence of design data on quality, providing practical tools for improving industrial processes._________

Epitaxial growth of WTe$_2$ offers significant advantages, including the production of high-qualityfilms, possible long range in-plane ordering and precise control over layer thicknesses. However,the mean island size of WTe$_2$ grown by molecular beam epitaxy (MBE) in litterature is only a fewtens of nanometers, which is not suitable for an implementation of devices at large lateral scales.Here we report the growth of Td-WTe$_2$ ultrathin films by MBE on monolayer (ML) graphenereaching a mean flake size of $\cong$110nm, which is, on overage, more than three time larger thanprevious results. WTe$_2$ films thicker than 5nm have been successfully synthesized and exhibit theexpected Td-phase atomic structure. We rationalize epitaxial growth of Td-WTe$_2$ and propose asimple model to estimate the mean flake size as a function of growth parameters that can be appliedto other transition metal dichalcogenides (TMDCs). Based on nucleation theory and Kolmogorov-Johnson-Meh-Avrami (KJMA) equation, our analytical model supports experimental data showinga critical coverage of 0.13ML above which WTe$_2$ nucleation becomes negligible. The quality ofmonolayer WTe$_2$ films is demonstrated from electronic band structure analysis using angle-resolved photoemission spectroscopy (ARPES) in agreement with first-principle calculationsperformed on free-standing WTe$_2$ and previous reports.

The thickness of freshly made soap films is usually in the micron range, and interference colors make thickness fluctuations easily visible. Circular patterns of constant thickness are commonly observed, either a thin film disc in a thicker film or the reverse. In this Letter, we evidence the line tension at the origin of these circular patterns. Using a well controlled soap film preparation, we produce a piece of thin film surrounded by a thicker film. The thickness profile, measured with a spectral camera, leads to a line tension of the order of 0.1 nN which drives the relaxation of the thin film shape, initially very elongated, toward a circular shape.A balance between line tension and air friction leads to a quantitative prediction of the relaxation process. Such a line tension is expected to play a role in the production of marginal regeneration patches, involved in soap film drainage and stability.

In this contribution, a new POM-based ionic liquid, namely (P6,6,6,14)4[W10O32], was fully characterized. Its viscosity and its very low dielectric constant make this hybrid ionic liquid suitable to be used as solvent for organic transformations. As proof of concept, this unique ionic liquid combining solvant and catalyst properties was tested for catalytic oxidation of various alcohols and alkenes in presence of H2O2

The properties of confined granular flows are studied through discrete numerical simulations. Two types of flows with different boundaries are compared: (i) gravity-driven flows topped with a free surface and over a base where erosion balances accretion (ii) shear-driven flows with a constant pressure applied at their top and a bumpy bottom moving at constant velocity. In both cases we observe shear localization over or/and under a creep zone. We show that, although the different boundaries induce different flow properties (e.g. shear localization of transverse velocity profiles), the two types of flow share common properties like (i) a power law relation between the granular temperature and the shear rate (whose exponent varies from 1 for dense flows to 2 for dilute flows) and (ii) a weakening of friction at the sidewalls which gradually decreases with the depth within the flow.

The most commonly observed quantity related to light is its power or equivalently its energy. It can be either measured with a bolometer, a photodiode or estimated with the naked eye. Alternatively people can measure the light impulse or linear momentum. However, linear momentum is characterized by its transfer to matter, and its precise value is most of the time of little use. Energy and linear momentum are linked and can be deduced from each other, from a theoretical point of view. Because the linear momentum measurement is more difficult, energy is the most often measured quantity. In every physical process, angular momentum, like energy and linear momentum is conserved. However, it is independent and can't be deduced from the energy or the linear momentum. It can only be estimated via its transfer to matter using a torque observation. Nevertheless , experimentally, the torque is found to be proportional to the optical power. This leads to a need of a quantum interpretation of the optical field in terms of photons. Clear experimental evidences and consequences are presented here and debated. light temperature rotation $\theta$ velocity energy flux light angular momentum light radiation pressure

We report the experimental observation of the bifurcation at the origin of localization of the deformation in a granular material submitted to uniaxial compression. We present a quantitative characterization of the heterogeneity in the strain field repartition allowing to evidence objectively the existence of a bifurcation initiating the shear bands formation process. We show that this bifurcation is supercritical and has no clear signature on the stress-strain curve. At the bifurcation, a symmetry breaking occurs characterized by the emergence of a well-defined orientation corresponding to the Mohr-Coulomb angle. Yet, plasticity is still diffuse and the shear band extension is of the order of the sample width. While loading proceeds, the shear band narrows until it reaches, after the peak of the stress-strain curve, a stationary width.