Mouloud Mammeri University of Tizi-Ouzou

The high production cost of biosurfactants remains a major limitation to their large-scale application in environmental remediation and industrial processes. This study investigated the use of low-cost agro-industrial and fishery residues as alternative substrates for biosurfactant production by Pseudomonas aeruginosa MELI 1 isolated from hydrocarbon-contaminated soil. Four waste-derived feedstocks, namely prickly pear peels, sardine heads, chicken feet, and ripened dates, were evaluated and compared with a glucose-based medium. Among the tested substrates, prickly pear peels supported the highest biosurfactant production (13.30 ± 0.61 g L−1 crude extract), biomass concentration (3.10 ± 0.15 g L−1), and substrate-to-product conversion yield (Y_P/S = 0.346 g g−1 crude extract; 0.208 g g−1 purity-corrected). Sardine-head medium exhibited the highest emulsification activity (E24 = 64%), whereas date-derived medium achieved the highest cleaning performance. Kinetic analysis based on the Luedeking–Piret model indicated that biosurfactant production was predominantly growth-associated across all substrates. Surface tension was reduced from 72.0 to 28.5 mN m−1, and the critical micelle concentration was determined to be 85 mg L−1. Colorimetric assays and FTIR spectroscopy indicated the production of a glycolipid-type biosurfactant exhibiting characteristics consistent with rhamnolipid-like compounds. However, definitive structural identification requires advanced analytical techniques such as LC-MS/MS or NMR spectroscopy. The biosurfactant maintained functional activity over a broad range of pH and temperature conditions. A preliminary techno-economic assessment suggested that the use of waste-derived substrates substantially reduced feedstock costs relative to the glucose-based medium, with prickly pear peels showing the most favorable balance between production performance and estimated process economics. Further studies involving advanced structural characterization, process scale-up, and comprehensive techno-economic evaluation are required.Overall, the results demonstrate the potential of agro-industrial and fishery residues as renewable feedstocks for biosurfactant production and support their valorization within circular bioeconomy strategies aimed at waste reduction, resource recovery, and sustainable environmental remediation.

This paper introduces a novel adaptive neural phase-locked loop (AN-PLL) based on an adaptive linear neuron (ADALINE) for grid-connected converters synchronization. The suggested AN-PLL contains two main stages; a zero-crossing-based frequency detector (ZCFD) in series with an ADALINE-based fundamental component estimator (AN-FE). In the first stage, a ZCFD accurately tracks the grid frequency, even under severe waveform distortions, harmonic disturbances, or the presence of DC offsets. In the second stage, the ADALINE estimates the fundamental component of the grid voltage, providing, after convergence, both its amplitude and phase angle. The use of the ADALINE is motivated by its fast convergence, inherent filtering capability, and simplicity, as it requires tuning of only one learning parameter. In the proposal, ZCFD and AN-FE work together to form a robust, fast, and easy-to-implement synchronization method, resilient to various grid disturbances. Performance assessment of the AN-PLL is carried out by integrating it into a single-phase grid-connected photovoltaic system. Both simulation and experimental tests were conducted, covering distorted grid conditions, frequency and voltage variations, and real-time power injection. For clarity and benchmarking, the developed AN-PLL is compared to an advanced enhanced PLL (EPLL), a widely recognized robust method in the literature. The proposed PLL effectively reduces estimation error, ensures fast dynamic response, and maintains low total harmonic distortion, even under grid distortions. Its strong tracking and rapid adaptation highlight its suitability for robust power electronic applications.

A series of ZnO/carbon‐based nanocomposites was successfully synthesized in situ within a starch matrix using a combination of precipitation and microwave‐assisted techniques, aiming at the efficient degradation of methyl orange (MO) under both UV and natural sunlight irradiation. Starch served simultaneously as a carbon source and a polymeric stabilizing agent during the synthesis. The morphology and elemental composition of the resulting nanomaterials were systematically characterized using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Fourier‐transform infrared (FTIR) spectroscopy. The Brunauer–Emmett–Teller (BET) method was applied to calculate the specific surface areas. The optical characteristics of the composites were investigated via UV–visible (UV–vis) spectrophotometry and photoluminescence (PL) spectroscopy. The findings revealed that the ZnO/carbon nanocomposite calcined at 400°C exhibited superior photocatalytic performance, achieving a 92% degradation efficiency of MO under UV light in 90 min, and 99% degradation under sunlight within 70 min. These efficiencies were approximately 2.7 and 4.2 times higher, respectively, than those obtained with ZnO/carbon treated at 200°C and pristine ZnO. The underlying photocatalytic mechanism was elucidated through radical scavenging experiments, indicating that hydroxyl radicals (·OH) were the predominant reactive species involved in the degradation process. Additionally, the photocatalytic performance of the ZnO/carbon nanocomposites calcined at 400°C was found to be strongly influenced by both the starch‐to‐precursor ratio and the pH of the synthesis medium.

This research examines a system combining the Organic Rankine Cycle (ORC) with the Auto-cascade Refrigeration Cycle (ARC), driven by a low-grade heat source, to produce ultra-low temperatures. In the ARC, a zeotropic mixture of R170 and R290 is used to achieve temperatures ranging from -65 degrees C to -45 degrees C. In the ORC, to ensure efficient operation, various dry working fluids such as R245fa, R245ca, RE245cb2, RE245fa2, R1224yd (Z), R1233zd (E), and R1336mzz (Z) were tested. A comprehensive thermodynamic model was developed to assess system performance. A subsequent parametric study was conducted to investigate the effect of condensing parameters on these performances. Variations in the COP, exergy destruction, and global exergy efficiency were evaluated. The results clearly show that low-grade thermal energy can be used to achieve ultra-low temperatures. Increasing the mass fraction of R170 (from 0.3 to 0.7) results in a 22.22% improvement in the COPARC, mainly due to a decrease in the compression ratio, thereby increasing the refrigerating capacity. The R245ca provides the highest mechanical power (21.3 kW) and cooling capacity (6.53 kW), whereas the RE245fa2 achieves the best exergy efficiency (similar to 9.5% at 30 degrees C). Furthermore, Low-GWP fluids (R1224yd(Z), R1233zd(E), R1336mzz(Z)) display very low TEWI values of less than 0.2 TonCO(2)-eq. Increasing condensing temperature from 30 to 45 degrees C reduces the efficiency of the ORC by approximately 31%. Under extreme conditions (-65 degrees C, 40 degrees C), R1336mzz (Z) is recommended for its optimal performance/environmental impact trade-off (COP approximate to 0.03; TEWI = 0.188 Ton CO2-eq.). Exergy analysis shows that exergy loss is mainly attributed to the compressor, boiler, and evaporator.

This study investigates the combined rheological, mechanical, and environmental performance of selfcompacting mortars (SCMs) incorporating dune sand powder (DSP) and marble waste powder (MWP) as sustainable clinker substitutes. A Box-Behnken design (BBD) coupled with life cycle assessment (LCA) was applied to optimize the water-to-binder ratio (0.35-0.45) and replacement levels (0-25%). Fresh (flow), hardened (compressive strength, CS), and durability (water absorption, W) properties were modeled alongside four LCA indicators: climate change (CC), energy resources (ER), material resources (MR), and human toxicity (HT). Moderate DSP and MWP substitutions in the 10-15% range led to notable performance improvements. The highest measured compressive strength reached 59.17 MPa in the optimized mixture, while water absorption decreased to approximately 4.5%, indicating a denser matrix. Environmental analysis via LCA showed reductions in CO2 emissions by approximately 35% and energy consumption by nearly 20% relative to the control mix. These findings are supported by statistically robust quadratic models, with R2 values exceeding 0.98 across all response variables. This integrated experimental-environmental framework confirms that DSP and MWP act as effective, low-cost supplementary materials capable of reconciling mechanical performance with sustainability goals. The findings provide a quantitative basis for designing eco-efficient SCMs adapted to regions rich in desert sand and marble waste.