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Single-molecule localization microscopies have gained much attention for their efficient realization of a sub-diffraction-limit imaging with the resolution down to the 10-nm range. In contrast to conventional localization microscopes, which rely on particular fluorescent probes in specific conditions, metamaterial-assisted super-resolution microscopies can be implemented with any fluorescent dye under general conditions. Here, we present a systematic study of fluorescence engineering in metamaterial assisted localization microscopy by using cyclic group metasurfaces coated with a fluorescent film. Tailored variations are clearly demonstrated in both the photoluminescence intensity and the photobleaching lifetime of fluorophores based on the spatially varied Purcell effect near the metasurfaces. The enhanced emissions and blinking dynamics of the fluorophores on these metasurfaces lead to an increased signal-to-noise ratio, and therefore give rise to a super-resolution localization image with 0.9-nm localization accuracy. Our results are not only beneficial for super-resolution localization imaging but also push the control of light–matter interactions beyond the diffraction limit.

The relationship between the gut microbiota, short chain fatty acid (SCFA) metabolism, and obesity remains unclear due to conflicting reports from studies with limited statistical power. Additionally, this association has rarely been explored in large scale diverse populations. Here, we investigated associations between fecal microbial composition, predicted metabolic potential, SCFA concentrations, and obesity in a large (N= 1,934) adult cohort of African-origin spanning the epidemiologic transition, from Ghana, South Africa, Jamaica, Seychelles, and the United States (US). The greatest gut microbiota diversity and total fecal SCFA concentration was found in the Ghanaian population, while the lowest levels were found in the US population, respectively representing the lowest and the highest end of the epidemiologic transition spectrum. Country-specific bacterial taxa and predicted-functional pathways were observed, including an increased prevalence ofPrevotella,Butyrivibrio,WeisellaandRomboutsiain Ghana and South Africa, whileBacteroidesandParabacteroideswere enriched in Jamaican and the US populations. Importantly, ’VANISH’ taxa, includingButyricicoccus and Succinivibrio, were significantly enriched in the Ghanaian cohort, reflecting the participants’ traditional lifestyles. Obesity was significantly associated with lower SCFA concentrations, a decrease in microbial richness, and dissimilarities in community composition, and reduction in the proportion of SCFA synthesizing bacteria includingOscillospira,Christensenella,Eubacterium,Alistipes,ClostridiumandOdoribacter. Further, the predicted proportions of genes in the lipopolysaccharide (LPS) synthesis pathway were enriched in obese individuals, while genes associated with butyrate synthesis via the dominant pyruvate pathway were significantly reduced in obese individuals. Using machine learning, we identified features predictive of metabolic state and country of origin. Country of origin could accurately be predicted by the fecal microbiota (AUC = 0.97), whereas obesity could not be predicted as accurately (AUC = 0.65). Participant sex (AUC = 0.75), diabetes status (AUC = 0.63), hypertensive status (AUC = 0.65), and glucose status (AUC = 0.66) could all be predicted with different success. Interestingly, within country, the predictive accuracy of the microbiota for obesity was inversely correlated to the epidemiological transition, being greatest in Ghana (AUC = 0.57). Collectively, our findings reveal profound variation in the gut microbiota, inferred functional pathways, and SCFA synthesis as a function of country of origin. While obesity could be predicted accurately from the microbiota, the variation in accuracy in parallel with the epidemiological transition suggests that differences in the microbiota between obesity and non-obesity may be larger in low-to-middle countries compared to high-income countries. Further examination of independent study populations using multi-omic approaches will be necessary to determine the factors that drive this association.

Irrigated rice production is common in the coastal savannah zone of Ghana. Recent observations have shown the incidence of a new leaf spot disease in some rice basins in the area. Research was carried out to determine the incidence and severity of the disease in the area, identify the causal agent using its cultural and morphological features, complemented with phylogenetic studies of the internal transcribed spacer region. Also, the effect of some selected fungicides and an antagonistic Trichoderma harzianum on the mycelial growth of the fungus was determined in vitro. The disease was found in all the major rice growing districts in the coastal savannah zone with severities ranging from 22.6 to 50.9%. Curvularia lunata was identified as the causal agent of the disease. Carbendazim, Nordox and Mancozeb, totally depressed the mycelial growth of the fungus whiles T. harzianum inhibited the growth of the fungus. These fungicides and antagonistic organism have the potential for the control of the disease in the field.

International audience; With the rapid progress in the field of metasurfaces and their use in miniature integrated devices arise the quest for cheap mass production of efficient metasurfaces. We suggest a novel way to design and fabricate phase-gradient Huygens metasurfaces using laser-annealing of uniform particles made of As2S3 chalcogenide glass. We show that a phase gradient metasurface can be realized by tuning the refractive index of otherwise identical meta-atoms instead of tuning their geometry. We are using an array of identical As2S3 particles with the possibility to locally change their refractive index using a short-wavelength illumination (green laser) in order to tune the phase 1 pattern at the post-fabrication stage. Metasurfaces fabricated with this method can be used for operation in the red or IR spectral range. We fabricate uniform As2S3 Huygens metasurfaces using electron beam lithography and demonstrate their post-fabrication tuning with exposure of comparatively low intensity. Samples characterization with transmittance measurement and quantitative phase microscopy provide results in good correspondence with numerical predictions confirming post-fabrication spectral tuning. Using such tuning, we demonstrate the possibility to transfer the intensity pattern produced by modifying a writing beam with a spatial light modulator to a phase pattern recorded on a uniform As2S3 metasurface. Our method has potential advantages for the low-cost production of large-scale metasurfaces because uniform geometries are better adjusted for mass manufacturing.

The main aim of this study was to investigate how large class size and teacher-to-learner ratio affect classroom management in early childhood educational centres in Ghana. A descriptive survey was used as research design for the study, which was underpinned by positivist philosophical thought. The data was collected using a four-point Likert-type scale questionnaire, to be administered to preschool teachers and head teachers. The sample size for the study was 216 participants and the data was analysed using one-way analysis of variance (ANOVA), mean and standard deviation. It was found that the presence of teacher-to-learner ratio (TLR) in early childhood education centres (ECECs) resulted in poor interaction and communication between preschool teachers and pre-schoolers, which had an effect on teachers’ classroom management. Moreover, in large classes, where teachers are unable to perform effective classroom management, classroom discipline and engagement will be more difficult to achieve than in the smaller classes. Again, the findings revealed that in cases of large class size, preschool teachers were repeating activities and were unable to attend to two events simultaneously in the classroom without having their attention diverted unduly by disruptions. The study also pointed out that positive reinforcement, shaping, giving prompt feedback and giving clear instructions were effective classroom strategies used in managing pre-schoolers in classes of larger size.

This study investigated the effect of training and development on staff performance at the University of Mines and Technology, Tarkwa (UMaT). The specific objectives were: to investigate the measures put in place for training and development of staff; assess the effect of training and development on staff performance at UMaT. The descriptive survey research design was adopted for the study. Through the use of stratified sampling, simple random sampling, and purposive sampling procedures, 202 non-teaching staff members comprising of senior members, senior staff and junior staff members were involved in the study. A self-developed questionnaire with internal consistency of 0.65 was used to gather the requisite data for the study. Data were analysed using descriptive and inferential statistics such as frequencies, percentages, mean of means distributions and Pearson product moment correlation. The study found out that measures existed at UMaT for training and development of staff and that, the University management organises regular training programmes based on identification of needs assessment. Also, training and development improved staff performance at UMaT and increased staff’s efficiency on the job. However, study leave with pay were not granted to staff which is likely to affect staff performance. The study recommended that the University management should continue with the regular training and development programmes. Also, a window of opportunities for administrative staff to be granted study leave with pay for further training should be created.

Stress may be caused by psychological, physiological, environmental and physical factors. The aim of the study was to investigate the ameliorative and anti-oxidative effects of levamisole on stress, and the comparative efficacy of levamisole and Ivermectin in the control of Strongyle infection in donkeys. Adult male donkeys (n = 35) aged between 4–5 years; 25 naturally infested with Strongyle spp and 10 apparently healthy (free of helminth infestation) were selected for this study, divided broadly into 2 groups: Anthelmintic efficacy study group comprising 20 (10 donkeys for Ivermectin efficacy studies and the other 10 for Levamisole efficacy study on clearing strongyles from the gastro-intestinal tract of donkeys). The oxidative stress amelioration groups were A, B, C of five donkeys each: Groups A and B donkeys were the apparently healthy group; while Group C donkeys were naturally infected with Strongyle spp. All the donkeys in the oxidative stress amelioration group participated in packing of 40 kg for 10 km. Groups B and C were treated with levamisole at 7.5 mg/kg, while Group A received no treatment prior to packing. Blood was collected from all donkeys in the oxidative stress amelioration group for haemogram and oxidative stress biomarker analyses. No significant effect (P > 0.05) was observed between groups: A, B and C for: respiratory rate, pulse rate and rectal temperature; haemogram, and malondialdehyde concentration, activities of superoxide dismutase and catalase. Erythrocyte membranes were osmotically stable at 0.5% NaCl in the treated group in comparison to the controls. Packing of donkeys for 10 km did not induce significant changes in vital parameters, haemogram and biomarkers of oxidative stress, but levamisole improved erythrocyte membrane stability. It was concluded that packing for 10 km did not induce any significant changes in blood cellular components and biomarker of oxidative stress, but levamisole improved erythrocyte membrane stability. Ivermectin was administered at a dose rate of 0.2 mg /kg per os and Levamisole at a dose rate of 7.5 mg/kg per os for the helminth efficacy study. Levamisole efficacy treatment group had a reduction test of 86.8% while Ivermectin efficacy study group had 76%. This may indicate occurrence of resistance to both drugs in the donkeys. Further research is needed in order to obtain the efficacy of this drugs in a larger population There is a need to develop better and improved management practices to combat and ameliorate the challenge that helminthosis in donkeys posses to the health and working performance of donkeys.

International audience; Understanding how gas molecules such as water, oxygen, or carbon monoxide interact with nanoparticles NPs remains an important challenge in the studies of atmospheric chemistry and catalysis reactions.When gas molecules are directly adsorbed onto Au nanodisks (direct nanoplasmonic sensing DNPS) or when they interact with NPs supported on Au nanodisks (indirect nanoplasmonic sensing INPS), they modify the local dielectric properties of the surrounding media. Such a modification induces a wavelength shift of the localized surface plasmon resonance (LSPR) of Au nanodisks which can be easily detected by UV-Vis spectroscopy.We measured water adsorption isotherms by DNPS following the Au LSPR shift when water molecules adsorb/desorb on Au nanodisks [1]. With high sensitivity, we used INPS to follow also the interaction of water molecules on soot NPs that are a significant contributor to global warming in the atmosphere.Then, CO and oxygen adsorption as well as CO oxidation, on Pt NPs, have also been followed by INPS coupled with mass spectrometry [2]. We obtained a quantitative and very sensitive probe even for a very low Pt NPs density. For both DNPS and INPS, we could detect small molecule quantities such as a few hundredths of an adsorbed monolayer. Moreover, we can use nanoplasmonic sensing in a large range of pressure and temperature.FDTD calculations are performed to interpret LSPR spectra and to optimize the physical parameters of our plasmonic nanosensors.

International audience; The goal of this poster presentation is to give an overview of nanofabrication techniques commonly used for the realization of nanostructures in our micro and nanofabrication facilities. We focus on the process equipment available in the CINaM clean room. We will also present some recent scientific results in photonics obtained on plasmonics nano-arrays for molecular sensing (collaboration with B. Demirdjian’s group) [1] and on transition metal dichalcogenide structures showing a non-linear coupling between excitons and Mie scattering resonances in the visible and near infrared spectral regions (collaboration with G. Tselikov) [2]. We will also present the fabrication of nanocluster arrays used for detection of hidden features in the architecture of T-lymphocyte cells (collaboration with K. Sengupta’s group) [3]. Finally, we will present our recent results on fabrication of sharp silicon arrays to wound Caenorhabditis elegans worms (collaboration with J.J. Ewbank’s group) [4].All micro and nanostructures were obtained in our clean room facilities using nanofabrication tools such as optical and electron beam lithography, magnetron sputtering or thermal evaporation and chemical or reactive ion etching.The PLANETE platform is open to the regional scientific research community as well as to innovative companies carrying out research and development projects. All the cleanroom facilities and equipment are available to them to carry out their projects with technical assistance from the platform staff according to their needs.[1] B. Demirdjian, I. Ozerov, F. Bedu, A. Ranguis, and C.R. Henry, ACS Omega 6, 13398 (2021)[2] A.A. Popkova et al. Laser & Photonics Reviews 16, 2100604 (2022)[3] A. Nassereddine et al. Nano Letters 21, 5606 (2022)[3] J. Belougne, I. Ozerov, C. Caillard, F. Bedu, J.J. Ewbank, Scientific Reports 10, 3581 (2020)

International audience; Hybrid van der Waals heterostructures made of 2D materials and organic molecules exploit the high sensitivity of 2D materials to all interfacial modifications and the inherent versatility of the organic compounds [1-2]. In this study, we are interested in the quinoïdal zwitterion/MoS2 hybrid system in which organic crystals are grown by epitaxy on the MoS2 surface and can reorganize in other forms after thermal annealing [3]. By means of field effect transistor measurements and atomic force microscopy, we demonstrate that the charge transfer between organic molecules and 2D materials strongly depends on the conformation of the molecular film. This work shows the great sensibility of MoS2 transistors for sensing molecular events occurring at the nanoscale providing a new experimental tool in addition to the usual microscopies and spectroscopies techniques.References :[1] Late, D. J.; Huang, Y.-K.; Liu, B.; Acharya, J.; Shirodkar, S. N.; Luo, J.; Yan, A.; Charles, D.; Waghmare, U. V.; Dravid, V. P.; Rao, C. N. R. Sensing Behavior of Atomically Thin-Layered MoS 2 Transistors. ACS Nano 2013, 7 (6), 4879–4891. [2] Li, N.; Wang, Q.; Shen, C.; Wei, Z.; Yu, H.; Zhao, J.; Lu, X.; Wang, G.; He, C.; Xie, L.; Zhu, J.; Du, L.; Yang, R.; Shi, D.; Zhang, G. Large-Scale Flexible and Transparent Electronics Based on Monolayer Molybdenum Disulfide Field-Effect Transistors. Nat. Electron. 2020, 3 (11), 711–717.[3] Lockhart de la Rosa, C. J.; Phillipson, R.; Teyssandier, J.; Adisoejoso, J.; Balaji, Y.; Huyghebaert, C.; Radu, I.; Heyns, M.; De Feyter, S.; De Gendt, S. Molecular Doping of MoS 2 Transistors by Self-Assembled Oleylamine Networks. Appl. Phys. Lett. 2016, 109 (25), 253112.