The integration of augmented and virtual reality in cell biology courses as a pedagogical innovation in the training of life and earth sciences teachers

Teaching and learning using mobile devices such as tablets and smartphones has become a trend. Learners can use mixed reality technologies including augmented reality (AR) and virtual reality (VR) which are promising tools for science education. Augmented reality allows the user to see a combination of the real world and virtual objects, while virtual reality generates a virtual environment in which the user feels like in the real world. Several studies have focused on the contribution of AR/VR in different fields of education and have shown that this technology positively affects learners' motivation, promotes their self-learning, and can improve their academic performance. Our study was designed to investigate the contribution of activities integrating augmented and virtual reality in cell biology courses, on the learning and motivation of Moroccan pre-service teachers of life and earth sciences. We adopted a semi-experimental approach using a pre-test and a post-test with two groups. The pre-service teachers in the experimental group (n= 30) took the courses using AR/VR materials and tools, while the pre-service teachers in the control group (n=30) took the same courses using only traditional tools and materials. The results of the pre-test and post-test showed a statistically significant difference in the post-test in favour of the pre-service teachers of the experimental group who, in addition to the improvement in their test scores, expressed high motivation during the different training courses

Starch and polyvinyl alcohol encapsulated biodegradable nanocomposites for environment friendly slow release of urea fertilizer

Low nitrogen (N) use efficiency from urea fertilizers due to environmental losses results in high cost of fertilizers for agricultural productions. Coating of urea with biodegradable polymers makes them effective for control and efficient N release. In this study, starch and polyvinyl alcohol (PVA) were used in combination with acrylic acid (AA), citric acid (CA) and maleic acid (MA) for the coating of urea prills. Different formulations of the coating were prepared and applied on urea prills such as urea coated with starch (10%) and PVA (5%) with acrylic acid: 2, 4 and 6% (USP-A2, USP-A4, USP-A6), with citric acid: 2, 4 and 6% (USP-C2, USP-C4, USP-C6), and with maleic acid: 2, 4 and 6% (USP-M2, USP-M4, USP-M6). After urea coating in fluidized bed coater, all uncoated and coated urea samples were characterized by scanning electron spectroscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), crushing strength and UV-Vis spectroscopy. The morphological and XRD analysis indicated that a new uniform coating with no new phase transformation occurred. Among all urea coated samples, USP-A2 and USP-C2 showed the highest crushing strengths: 12.08 and 13.67 N with nitrogen release efficiency of 70.10 and 50.74% respectively. All coated urea samples improved the spinach plants’ foliage yield, chlorophyll content, N-uptake and apparent nitrogen recovery (ANR) than uncoated urea and control plants. However, USP-A2 and USP-C2 provided promising results among all coated samples with dry foliage yield (2208 ± 92 and 2428 ± 83 kg/ha), chlorophyll (34 ± 0.6 and 34 ± 0.4 mg/g), N-uptake (88 ± 4 and 95 ± 6 kg/ha) and ANR (59 ± 4 and 67 ± 6%). Therefore, urea prills coated with a combination of biodegradable polymers can be a better choice for the farmers to enhance agronomical productions by controlling the fertilizer nutrient release rate

Bismuth Nanoparticles Supported on Biobased Chitosan as Sustainable Catalysts for the Selective Hydrogenation of Nitroarenes

International audienceThe use of chitosan as a support in the field of catalysis has gained tremendous interest because of its abundance and sustainability. We herein disclose a straightforward strategy to trap and stabilize bismuth nanoparticles (BiNPs) on chitosan biopolymer Bi@CS and their use for catalytic applications. Bi@CS was configured as micrometer-thick films, porous beads, and native powders analyzed and next used for the controlled and selective reduction of nitroaromatic compounds to their corresponding anilines and azoarenes, respectively, by varying the concentration medium in reducing NaBH 4. A regioselective mechanism has been suggested. Powder nanocomposites CSp-BiNPs exhibited high catalytic capacity, and 10 corresponding anilines and 15 azoarenes were obtained with very high yields. The reductions were achieved under mild and sustainable reaction conditions (water solvent and room temperature) with easy processing and 12 recovery cycles. Shaped catalysts were easily recovered by simple filtration. This catalyst, derived from nontoxic and affordable bismuth metal supported on chitosan ocean waste, presents significant improvements in the realm of sustainable chemistry and could open a new channel of possibilities for green catalysis

Exploiting poly(ε-caprolactone) grafted from hydrohydroxymethylated sunflower oil as biodegradable coating material of water-soluble fertilizers

International audienceIn the present study, hyperbranched poly(ε-caprolactones) were prepared and used as coating materials to prepare slow release diammonium phosphate (DAP) fertilizer. Firstly, the sunflower oil was hydrohydroxymethylated by one-pot two-step process using Rh(acac)(CO)2 as catalyst, and triethylamine as ligand. Next, the bio-based hyperbranched poly(ɛ-caprolactone) (PCL) were prepared in open air by in-situ ring-opening polymerization of ε-caprolactone using hydrohydroxymethylated sunflower oil as macro-initiator and tetra(phenylethynyl)tin (Sn(C ≡ CPh)4) as catalyst. The structures of the prepared polymers (SFO-O-g-PCL) were confirmed by nuclear magnetic resonance (1H NMR) and the infrared spectroscopy (FTIR). Furthermore, molecular weight values around 20.000 g.mol−1 of PCL grafted in SFO-O-g-PCL were obtained, the thermal stability and morphology of the coated film were also evaluated using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) respectively. The hydrophobic character of the films prepared from SFO-O-g-PCL was confirmed by measuring the contact angle of water droplets. In the second part, the DAP granular fertilizers were uniformly coated by the prepared material (SFO-O-g-PCL) using a laboratory rotary drum. Then the slow release performance in water of the coated and uncoated DAP fertilizer granules was evaluated by tracking the cumulative concentration of P2O5 released. Thus, it was found that only 10 % of P2O5 was released after 2 h of essay from the coated DAP compared to a total release of P2O5 from uncoated DAP (conventional fertilizer) during the same period. This finding opens a wide perspective to combine the advantages of hydrophobic polyesters and bio-based oils to produce biodegradable coating agents

Synthesis and antibacterial behavior of bio-composite materials-based on poly(ε-caprolactone)/bentonite

Several clay minerals as inorganic fillers were incorporated to aliphatic polyester by various procedures. The target of enhancing the physicochemical properties of the resulting composite material leading thereby to overcome the limitations of neat polyesters. Still, bentonite (Bnt) as a clay mineral has been relatively unexplored as a reinforcing agent of the poly(ε-caprolactone) (PCL). In this study, a bio-nanocomposite based on poly (ε-caprolactone) & bentonite nanofiller was prepared by in-situ ring opening polymerization (ROP) of ε-caprolactone (ε-CL) under open air using tin-based catalyst. The obtained bio-composites (PCL-OBnt) were fully characterized to examine their structural interactions, thermal stability, mechanical, and morphological properties. Finally, the antimicrobial activity against S. epidermidis and S. aureus of the prepared bio-composites materials was evaluated

Mechanisms of Phosphorus Acquisition and Lipid Class Remodeling under P Limitation in a Marine Microalga

International audienceMolecular mechanisms of phosphorus (P) limitation are of great interest for understanding algal production in aquatic ecosystems. Previous studies point to P limitation-induced changes in lipid composition. As, in microalgae, the molecular mechanisms of this specific P stress adaptation remain unresolved, we reveal a detailed phospholipid-recycling scheme inNannochloropsis oceanicaand describe important P acquisition genes based on highly corresponding transcriptome and lipidome data. Initial responses to P limitation showed increased expression of genes involved in P uptake and an expansion of the P substrate spectrum based on purple acid phosphatases. Increase in P trafficking displayed a rearrangement between compartments by supplying P to the chloroplast and carbon to the cytosol for lipid synthesis. We propose a novel phospholipid-recycling scheme for algae that leads to the rapid reduction of phospholipids and synthesis of the P-free lipid classes. P mobilization through membrane lipid degradation is mediated mainly by two glycerophosphoryldiester phosphodiesterases and three patatin-like phospholipases A on the transcriptome level. To compensate for low phospholipids in exponential growth,N. oceanicasynthesized sulfoquinovosyldiacylglycerol and diacylglyceroltrimethylhomoserine. In this study, it was shown that anN. oceanicastrain has a unique repertoire of genes that facilitate P acquisition and the degradation of phospholipids compared with other stramenopiles. The novel phospholipid-recycling scheme opens new avenues for metabolic engineering of lipid composition in algae

Microstructuration of Silicon Surfaces Using Nanoporous Gold Electrodes

International audienceEtching is a key process in the fabrication of silicon (Si) microstructures that are essential for several component families used in microelectronics, photonics and photovoltaics, among others. A large variety of microstructuring technologies exists nowadays (e.g. wet/dry etchings based on photo/electron beam lithography patterning). Their remarkable efficacy comes at the expense of several lithography (masking) /etching steps that are not suitable for all industries, i.e. when reduced cost and manufacturing time are key aspects (e.g. Si solar cells manufacturing). Hence, the development of a maskless technique with direct imprinting of patterns would dramatically simplify the fabrication process. However, eliminating the use of masks and move towards micromachining techniques has turned to be extremely challenging. Only a few achievements in the field of (electro)chemistry have been reported in the literature [1-4]. The most recent development is an electrochemical version of the metal assisted chemical etching method used to produce high aspect ratio nanostructures: a noble metal electrode is put in contact with a Si sample in a HF solution and polarized against a counter electrode; in the contacted areas the metal plays the role of etching tool by oxidizing/dissolving Si atoms [2,3]. The major problem encountered with this configuration lies in the intimate Si/metal contact, which hinders electrolyte supply over macroscopic distances. Hence, etching is very slow, starting from the edge of the metal tool and progressing laterally. An efficient pattern transfer has been recently demonstrated in the case of porous Si etching with a gold coated stamp, the porous Si network allowing the electrolyte to reach the Si/Au interface [4]. In this work, we present a new strategy to achieve pattern transfer into Si by a single step electrochemical (EC) contact etching with large dimension metal tools, as schemed in Figure 1a. Figure 1. a) Scheme of the electrochemical contact etching process; b, c) optical and SEM images of a n-type (100) Si surface after imprinting a pattern of inverted pyramids with d) a nanoporous Au electrode. The problematic diffusion of the electrolyte is solved by using for the first time nanoporous metal electrodes, which give access for the electrolyte to the whole Si/metal interface. Thus, etching is achieved with a priori no restriction on the dimensions of the treated surfaces. Our first results demonstrate the transfer of a well-defined array of square inverted pyramids over a treated area of approximately 1 mm 2 (Figure 1b and 1c) in a single step and without any prior lithography or masking process of the substrate. The etched pyramids are not aligned with the [001] and [010] directions of the (100) oriented sample (21° off) which clearly indicate that the pattern transfer is independent of the crystallographic orientation. This is a proof of concept for EC contact etching with nanoporous metal imprints, with a high potential for Si surface texturization (e.g. solar cells) [5]

Implementation and Characterization of a Laminate Hybrid Composite Based on Palm Tree and Glass Fibers

In this work, laminated polyester thermoset composites based on palm tree fibers extracted from palms leaflets and glass mats fibers were manufactured to develop hybrid compositions with good mechanical properties; the mixture of fibers was elaborated to not exceed 25 vol.%. Samples were prepared with a resin transfer molding (RTM) method and mechanically characterized using tensile and flexural, hardness, and impact tests, and ultrasonic waves as a non-destructive technique. The water sorption of these composite materials was carried out in addition to solar irradiation aging for approximately 300 days to predict the applicability and the long-term performance of the manufactured composites. Results have shown that the use of glass fibers significantly increased all properties; however, an optimum combination of the mixture could be interesting and could be developed with less glass sheet and more natural fibers, which is the goal of this study. On the other hand, exposure to natural sunlight deteriorated the mechanical resistance of the neat resin after only 60 days, while the composites kept high mechanical resistance for 365 days of exposure