Razrada i mehaničko-elektrokemijska karakterizacija antimon-olovnih pjena s otvorenim ćelijama izrađenim “Metodom prekomjerne replikacije soli” za moguću primjenu u proizvodnji olovno-kiselih baterija

In this study, open cell 25 % antimony-lead alloy foams are fabricated for possible use to lighten thick plates of lead-acid batteries. A new inexpensive and simple variant of the salt replication process is developed and explored. Different morphology and shapes have been successfully obtained with “excess salt replication” method (abbreviated as ESR method). Best porosity of about 68 % is obtained with salt particles size of about 3 mm. SEM and EDXS investigation of the composite salt/antimony alloy before NaCl leaching revealed the presence of the lead oxides microfilm coating cell walls and becoming lead carbonates after salt removal. Uniaxial compressive behaviour of the resulting cellular materials is studied for foams with porosities between 45 % and 70 %, and salt grain size ranging between 2.5 and 5 mm. A higher plateau stress is reached compared to the results obtained in the literature working on the aluminium foams. The reproducibility of the process is proved along samples. This work is licensed under a Creative Commons Attribution 4.0 International License.U ovom istraživanju izrađene su otvorene ćelije od 25 % antimon-olovnih pjena za moguću primjenu u osvjetljavanju debelih ploča olovno-kiselih baterija. Razvijena je i istražena nova jeftina i jednostavna varijanta procesa repliciranja soli. Različite morfologije i oblici uspješno su dobiveni metodom “prekomjerne replikacije soli” (ESR metodom). Najbolja poroznost od oko 68 % dobivena je pri veličini čestica soli od oko 3 mm. SEM i EDXS ispitivanje kompozitne legure soli/antimona prije ispiranja s NaCl otkrilo je prisutnost mikrofilma olovnih oksida koji oblažu zidove ćelije i nakon uklanjanja soli postaju olovni karbonati. Jednoosno tlačno ponašanje dobivenih materijala ćelije proučava se za pjene s poroznošću između 45 % i 70 % i za veličine zrna soli između 2,5 i 5 mm. Postignuta je veća granica stlačivanja u usporedbi s rezultatima o aluminijskim pjenama dobivenim u literaturi. Ponovljivost postupka dokazana je na uzorcima. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Unveiling the Impact of Thiophanate-Methyl on Arthrospira platensis: Growth, Photosynthetic Pigments, Biomolecules, and Detoxification Enzyme Activities

Background: The intensive and injudicious use of pesticides in agriculture has emerged as a major concern due to its detrimental impact on aquatic ecosystems. However, the specific impact of broad-spectrum fungicides, such as Thiophanate-methyl (TM), on cyanobacteria remains a subject of ongoing research and debate. Methods: In order to fill this knowledge gap, The present study aimed to comprehensively investigate the toxicological effects of TM (10–30 µg/L) on the growth, photosynthetic pigments, oxidative stress, and biochemical composition of the non-nitrogen-fixing cyanobacterium Arthrospira platensis. Results: Our findings unequivocally demonstrated that TM exposure significantly inhibited the growth of A. platensis. Moreover, the decrease in chlorophyll content indicated a pronounced negative impact on the photosynthetic system of A. platensis caused by TM exposure. Notably, TM induced oxidative stress in A. platensis, as substantiated by a significant increase in lipid peroxidation (MDA) within the culture. Furthermore, the intracellular generation of hydrogen peroxide (H2O2) exhibited a positive correlation with higher TM dosages, while the levels of vital antioxidant enzymes, such as catalase (CAT) and ascorbate peroxidase (APX), exhibited a discernible decrease. This suggests that TM compromises the antioxidant defense mechanisms of A. platensis. Additionally, TM was found to enhance the activity of a plethora of enzymes involved in the detoxification of pesticides, including peroxidase (POD) and glutathione-S-transferase (GST), thereby indicating a robust detoxification response by A. platensis. Interestingly, exposure to TM resulted in a general suppression of biocomponent production, such as total proteins and total carbohydrates, which exhibited a diminishing trend with increasing TM concentration. Conversely, the lipid content witnessed a significant increase, possibly as an adaptive response to TM-induced stress. Conclusions: These findings contribute to a deeper understanding of the ecological implications of pesticide usage and emphasize the urgent need for the adoption of sustainable and environmentally-friendly agricultural practices to safeguard aquatic ecosystems

Experimental Investigation of Fluid Flow through Zinc Open-Cell Foams Produced by the Excess Salt Replication Process and Suitable as a Catalyst in Wastewater Treatment

International audienceThe "excess salt replication process" is a new simple method of fabrication of open-cell metal foam based on the commonly known salt replication method. Porous materials with porosity between 46% and 66% result when the employed alloy is 25% antimonial lead alloy and when it is 58% to 65% zamak 5. These foams are proposed as structured catalysts instead of packed beds in the treatment of wastewater. The local regimes influencing macroscopic air flow behaviour through these foams are delimited and boundaries are analysed in terms of sample length. Most of the experimental tests in this work exhibited a general trend of air flow in ESR foams dominated by the "strong inertia regime". It was established that the law governing the unidirectional air flow through these foams was the full cubic law. The permeability and inertia coefficient of five samples with a cell diameter between 2.5 and 4.5 mm were calculated, and an empirical correlation was fitted. The irregular cuboid shape of salt grains used in the ESR foam was the origin of the special cell form of ESR foams leading to an anisotropic ordered porous media. This can explain the macroscopic turbulence of air flow because there were many dead zones present in the corner of each cubic cell, thus causing kinetic energy loss starting at earlier regimes

Comparative Investigation of the Effect of EggshellPowder and Calcium Carbonate as Additivesin Eco-Friendly Polymer Drilling Fluids

Drilling fluid systems have seen the addition of new natural additives in recent years in order to replace traditional additives, improve their rheological properties, and ensure the functionality of the drilling fluid taking into account health and environmental factors. This paper aims to study and compare the effect of the addition of eggshell powder (ESP) as a native and local additive and calcium carbonate (CC) as a traditional and conventional additive on the rheological and filtration properties of the drilling fluid system based on Na-bentonite of the region of Meghnia (Algeria). The test results of 10, 20, and 30 g of CCwerecompared to the same concentrations of ESP.The findings showed that the CC with various concentrations (10, 20, and 30 g) increases the rheological properties and the mud density while it reduces the filter cake and the fluid loss values which are desirable, calcium carbonate had aslightly higher effect on the pH. The obtained results following the addition of ESP with different ratios revealed that the latter has a considerable impact on the plastic viscosity, the yield point, the gel strength, and the cake thickness. Additionally, the effect of the presence of eggshell as an additive in pH, fluid loss, and mud density was studied; we observed a slight increase in the pH, while the fluid loss values decreased. However, the mud density values increased. Beyond 20 g of eggshell, the properties of the mud becomeundesirable. Moreover, this study contributes tonewfindings and suggests that the utilization of waste food and local goods in drilling mud mixtures has a bright future respecting the percentages of use

Development of New Alkylated Carrageenan Derivatives: Physicochemical, Rheological, and Emulsification Properties Assessment

In this research, amphiphilic derivatives of kappa carrageenan (KC) were synthesized by hydrophobic modification with an alkyl halide (1-Octyl chloride). Three hydrophobic polymers with different degrees of substitution (DS) were obtained by the Williamson etherification reaction in an alkaline medium. The effect of the molar ratio (R = reagent/polymer) on the DS was investigated at different ratios (1, 2, and 3). The KC derivatives (KCRs) were characterized by different techniques such as FT-IR, 1H-NMR, X-ray Diffraction, Scanning electron microscopy, and a rheological assessment. The FT-IR and 1HNMR analyses confirmed the binding of the hydrophobic groups onto the KC molecule. The degrees of substitution calculated by 1H-NMR demonstrated that the derivative KCR3 (0.68) presented a higher degree of substitution compared to KCR1(0.45) and KCR2 (0.53). The XRD and SEM analyses revealed that the alkaline etherification conditions did not alter the morphological and crystallographic properties, as well as the rheological behavior of the obtained derivatives. The amphiphilic character of the KCRs was investigated using a conductivity method which revealed that the molecular aggregation occurred above the critical aggregation concentration (CAC). Decreasing CAC values of 0.15% (KCR1), 0.11% (KCR2) and 0.08% (KCR3)with the degree of substitution (DS) were found. Furthermore, KCR’s derivatives greatly improved the stability of oil/water emulsions as the droplet size decreased with increasing DS. The derivative (KCR3) with higher DS, showed a greater amphiphilic character, and improved emulsifying power

Advancing Water Quality Research: K-Nearest Neighbor Coupled with the Improved Grey Wolf Optimizer Algorithm Model Unveils New Possibilities for Dry Residue Prediction

International audienceMonitoring stations have been established to combat water pollution, improve the ecosystem, promote human health, and facilitate drinking water production. However, continuous and extensive monitoring of water is costly and time-consuming, resulting in limited datasets and hindering water management research. This study focuses on developing an optimized K-nearest neighbor (KNN) model using the improved grey wolf optimization (I-GWO) algorithm to predict dry residue quantities. The model incorporates 20 physical and chemical parameters derived from a dataset of 400 samples. Cross-validation is employed to assess model performance, optimize parameters, and mitigate the risk of overfitting. Four folds are created, and each fold is optimized using 11 distance metrics and their corresponding weighting functions to determine the best model configuration. Among the evaluated models, the Jaccard distance metric with inverse squared weighting function consistently demonstrates the best performance in terms of statistical errors and coefficients for each fold. By averaging predictions from the models in the four folds, an estimation of the overall model performance is obtained. The resulting model exhibits high efficiency, with remarkably low errors reflected in the values of R, R2, R2ADJ, RMSE, and EPM, which are reported as 0.9979, 0.9958, 0.9956, 41.2639, and 3.1061, respectively. This study reveals a compelling non-linear correlation between physico-chemical water attributes and the content of dry tailings, indicating the ability to accurately predict dry tailing quantities. By employing the proposed methodology to enhance water quality models, it becomes possible to overcome limitations in water quality management and significantly improve the precision of predictions regarding critical water parameters. © 2023 by the authors