•Natural fibres decreases the dry density of earth extrudates.•Natural fibres decreases the compressive strength of earth extrudates.•Natural fibres increases ductility and compressive strength of ...earth extrudates.•Xanthan gum improves the interface quality between earth and natural fibres.•Diss fibres surface roughness provides interesting reinforcing effects.
This paper deals with the development of sustainable building earth-based materials. More precisely, it addresses the study of the reinforcement of raw earth with natural fibres originated from Algeria (diss and date palm tree fibres) and their stabilisation with xanthan gum. The aim of this study is the design of extruded earth-based building blocks with improved mechanical properties such as compressive strength and ductility. The effects of separate and simultaneous addition of date palm trees or diss fibres (with length varying between 5 and 15 mm at dosages of 1.5 and 3% in volume) and stabiliser (xanthan gum and HMP at 1 and 2% of the dry earth mass) on the flexural and compressive strength of the stabilised and unstabilised extruded materials are compared. Results show that adding only fibers decreases the compressive strength of the earth in comparison with the unreinforced sample. It is also shown that diss fibres provides better reinforcing efficiency than date palm tree fibres and that a combined addition of xanthan gum and natural fibres create a synergic effect that greatly improved the material mechanical behaviour: higher compressive and tensile strengths and better ductile properties. These results are fully supported by microscopic observations and pull-out tests carried out on single fibres.
•Reinforcement strategies for earth depends on the clay mineralogy.•Fibers, Particles packing optimization and alginate are efficient for kaolinite clay soils.•Woven fabrics act efficiently for all ...kinds of soils.•Coupling reinforcement strategies can lead to earth-based composites with high compressive strength (18.5 MPa).
Earth-based mortars are commonly reinforced with bio-based materials such as straw or biopolymers. The aim of this work is to identify reinforcements that are able to improve the mechanical strengths and the ductility of an earth-based matrix. We have also attempted to describe the mechanisms of reinforcement involved in such materials. Firstly, a kaolinite-based clay soil was mixed with sand to achieve earth-based mortars with the highest density at the dry state. For this material (kaolinite-based mortar), we have shown that, at the same water content, the compressive strength at the dry state only depends on the dry density of the sample whatever the forming process. Various quantities of fibers, fabrics and alginate were then used to reinforce the studied mortars (a kaolinite based mortar and a natural soil containing swelling clay sieved at 4 mm). We found that these reinforcements significantly increase the compressive strength of all tested samples containing kaolinite. A comparison between the two materials helps us to understand the reinforcement mechanisms for various fibers; it also demonstrates that natural fibers and woven fabrics enhance the mechanical behavior of earth mortars notably under a compressive load.
Classical hydrophobic ionic liquids such as 3-butyl-1-methylimidazolium bis(trifluoroethylsulfonyl)imide or 3-butyl-1-methylimidazolium hexafluorophosphate application, as a non-aqueous liquid phase ...in a two-partitioning bioreactor to biodegrade hydrophobic volatile organic compounds by activated sludge, have been already reported in the literature, especially when the activated sludge was beforehand acclimated to the targeted volatile organic compound. In this study, four hydrophobic ionic liquids were used as non-aqueous liquid phase in a two-phase partitioning bioreactor to biodegrade toluene using non-acclimated activated sludge. The preliminarily results allowed to select two ionic liquids, 1-octylisoquinolinium bis(trifluoromethylsulfonyl)imide and allyl-diethylsulfonium bis(trifluoromethylsulfonyl)imide. The activated sludge was acclimated to both toluene and the considered ionic liquid. The results were compared to those obtained with non-acclimated activated sludge. The use of non-acclimated activated sludge for toluene biodegradation led to long lag times and low biodegradation rates. Thus, the acclimation to toluene improved the biodegradation rates; however, acclimation to both toluene and ionic liquid did not result in a significant improvement in the biodegradation rate compared to an acclimation to toluene alone. The activated sludge acclimation had a positive impact on toluene biodegradation and allowed to totally overcome the inhibitory effect of the presence of ionic liquid. The most relevant acclimation strategy seems to be a prior acclimation to toluene, whereas acclimation to the non-aqueous liquid phase can be achieved during the culture, namely by performing successive batches for instance, or a continuous operation.
2,3-dihydroxylated anthraquinone (2,3-DHAQ) is evaluated for the first time in a redox flow battery. This compound exhibits a good solubility in alkaline media (0.7 M in KOH at pH > 13.5) and a ...suitable potential (−0.85 V vs Ag/AgCl) leading to a 1.11 V theoretical open circuit voltage at 50% state of charge with potassium ferrocyanide as posolyte. It is implemented in a 25 cm2 cell during 180 cycles with a capacity fading of 0.022% per cycle and a current efficiency higher than 99.7%. Owing to its high solubility, an initial energy density up to 17 Wh L−1 (7.7 Wh L−1 when both posolyte and negolyte are considered) is obtained. 2,3-DHAQ exhibits a good chemical stability compared with other dihydroxyanthraquinone (around 0.1% per cycle). After more than 3000 cycles, 2,3-DHAQ is observed as the main product, showing its high chemical stability. Moreover, the capacity fading process is reversible since changing the discharge conditions allows a full recovery of the initial capacity. This opens up new perspectives as the capacity loss is often used to evaluate the relevance of new molecules. A wider range of active materials in AORFB can be considered if the capacity fading they exhibit can be reversible.
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•2,3-DHAQ is a new and promising negolyte for AORFB.•This aqueous RFB exhibits high energy efficiency and good cycling stability.•A 3000 cycles experiment was reported.•The observed capacity fading was reversible by modifying discharge parameters.
While raw earth can be used as a structural material, its water sensitivity limits its use in modern construction. Earth has a strong affinity with water. Both water imbibition and water vapour ...transfer have to be taken into consideration. This affinity can be a positive point to regulate indoor ambience, but it can also negatively affect earth’s mechanical properties. To avoid this possible detrimental effect, bio-based additions are used all around the world to stabilize, protect from water and enhance the mechanical properties of earth-based building materials. Bio-based stabilizers have to limit liquid water absorption and maintain mechanical properties without acting as a water vapour barrier that can lead to durability issues. In this article, capillary water absorption and water vapour permeability measurements are performed for combinations of various earths and bio-based additions (linseed oil, xanthan gum, casein, alginate and tannins). Linseed oil and xanthan gum help to protect the earth-based samples from absorbing liquid water without affecting the water vapour transfer in these materials.
To improve the industrial applicability of aqueous organic redox flow batteries (AORFB), inexpensive redox compounds highly soluble in aqueous medium and stable during cycling are required. Thus, a ...water-soluble quinizarin derivative, 1,4-dihydroxy-2-carboxymethyl-9,10-anthraquinone (1,4-CDHAQ) prepared by a one-pot synthesis from relatively low-cost leucoquinizarin (widely used as intermediate in the dye industry) is evaluated in AORFB. It exhibits a good solubility in basic medium (> 0.4 M) and a low potential (-0.64 V vs Ag/AgCl) leading to a cell voltage of about 1 V when paired with ferri/ferrocyanide couple. Long-cycling AORFB of 2.5 months performed at a concentration of 0.4 M gives good performance in terms of energy efficiency and power density. The influence of the temperature on ASR values and so on the power density underlines the difficulty to obtain reproducible results at room temperature. A capacity fade rate of 0.008 %/cycle (0.28 %/day) is obtained after 2500 cycles, which is close to other values reported for anthraquinones in strong basic medium for long-cycling tests. Interestingly, the discharge cut-off voltage clearly affects the stability of the battery, leading to the formation of different degradation products as shown by 1H NMR. These results highlight the importance of the cycling conditions to improve the battery performance.
Microalgae are considered a sustainable source of high-value products with health benefits. Marine algae-derived omega-3 long-chain polyunsaturated fatty acids (LC-PUFA), such as eicosapentaenoic ...acid (EPA) and docosahexaenoic acid (DHA), are considered dietary elements with effects on mental health, cognition enhancement, and cardiovascular protection. This study investigated the temperature effect on omega-3 LC-PUFA production in eight species of microalgae from various taxonomic groups, with a focus on achieving an optimal balance between omega-3 accumulation and efficient growth performance. Samples were batch-cultivated at four different temperatures, with constant light, and fatty acid methyl esters (FAME) were analyzed by gas chromatography. Several nutritional indices were calculated to assess the potential value of biomass produced for human consumption. Two promising candidates were identified suitable for batch cultivation and large-scale production:
Nannochloropsis oculata
for EPA and
Isochrysis galbana
for DHA production, with optimum productivities obtained between 14 and 20 °C, and nutritional indices falling within the range required for nutritional benefit.
This paper presents some numerical experiments in relation with the theoretical study of the ergodic short-term behaviour of discretizations of expanding maps done in P.-A. Guihéneuf and M. Monge, ...Cramér distance and discretizations of circle expanding maps I: theory, (2022). arXiv 2206.07991. Our aim is to identify the phenomena driving the evolution of the distance between the tth iterate of Lebesgue measure by the dynamics f and the tth iterate of the uniform measure on the grid of order N by the discretization on this grid. Based on numerical simulations we propose some conjectures on the effects of numerical truncation from the ergodic viewpoint.
Abstract In this article, we finish the classification of actions of torus homeomorphisms on the fine curve graph initiated by Bowden, Hensel, Mann, Militon, and Webb. This is made by proving that if ..., then acts elliptically on if and only if has bounded deviations in some direction . The proof involves some kind of slow rotation sets for torus homeomorphisms.
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