Hatem Dhaouadi

Hydroclimate variability in northern Africa, driven by the interactions between the mid-latitude westerlies and the West African Monsoon (WAM) and by variations in their intensity, represents a key control on hominin dispersal. However, the response of these atmospheric circulation systems to changing boundary conditions and their influence on precipitation during past climate states remain poorly constrained, largely because most well-dated terrestrial hydroclimate records are limited to the Holocene interglacial period. Here, we present a 300,000-year hydroclimate record from northernmost Africa based on speleothem growth in Tunisia. This record captures alternating humid and arid phases across multiple glacial–interglacial cycles, as well as superimposed millennial-scale variability. Speleothem growth occurred predominantly during interglacials, indicating humid conditions, whereas growth hiatuses correspond to arid glacial periods. The cave record suggests that humid phases in northernmost Africa were primarily driven by a southward displacement and intensification of the mid-latitude westerlies and the Mediterranean storm track during interglacials. Comparison with Saharan palaeolake records further indicates that both enhanced winter westerlies and a strengthened summer WAM were required to generate widespread wet conditions across northern Africa during interglacial periods. These results highlight the combined influence of winter and summer moisture sources in shaping long-term hydroclimate variability and defining habitable corridors across northern Africa over the past 300,000 years.

This study employs density functional theory (DFT) to quantify the electron donoracceptor properties and polarizability of organic iron(II) salts as reducing agents in indigo dyeing processes. The potential of some iron(II) salts to serve as environmentally friendly alternatives to the ecologically harmful sodium dithionite in the indigo dyeing process was investigated. A comparative analysis assessed the redox potential of reduced indigo and the color strength of dyed fabrics. Experimental results identified iron(II) gluconate as the most efficient, yielding superior color intensity. Theoretical calculations using B3LYP/LANL2DZ confirmed the superior electron-donating ability of iron(II) gluconate compared to the other iron(II) salts. The indigo reduction ability with the iron(II) salts was evaluated on the basis of complexation energies. The theoretical thermodynamic study reveals that the indigo-iron(II) gluconate complex is the most thermodynamically stable, requiring less energy input for its formation compared to the other complexes. Iron(II) salts-to-indigo electron donations in the complexes studied have been revealed by Mulliken charge analysis. These findings highlight the efficiency of DFT-based approaches in accurately predicting the reducing capacity of iron(II) salts and their suitability as eco-friendly alternatives in indigo dyeing applications.

The present study focuses on the functionalization of cellulose-based textiles with residual rosemary wax, a by-product of supercritical CO₂ extraction of essential oil. The main objectives of this study were to identify the chemical composition of rosemary wax using FTIR, GC-MS, and HPLC techniques, to optimize its application onto cellulose fabrics, and to evaluate the properties of the treated textiles fabrics. In order to verify the efficacy of the treatment, a series of tests were carried out. These included contact angle measurements, water and air permeability testing, breathability assessment, tensile tests, and color evaluation. The obtained results were promising and showed that the treated fabrics exhibited significant hydrophobicity, with a contact angle exceeding 120°, along with excellent color performance (K/S = 12), good wash and crock fastness and excellent light fastness. Furthermore, an evaluation was conducted to ascertain the durability of the treatment, which revealed that the level of hydrophobicity remained within acceptable limits, reaching a value of 98°. A more in-depth study was conducted using Density Functional Theory (DFT) simulations were conducted to investigate the interactions between rosemary wax and cellobiose. This study revealed strong interactions with significant binding energies of -20.33 kcal/mol with carnosic acid and − 18.33 kcal/mol with apigenin, respectively. These interactions were further substantiated by bond critical point (BCP) analyses. The findings indicate that the use of derived wax in the functionalization of hydrophobic textiles is therefore a smart, successful and sustainable way of being part of the circular economy. This maximizes waste and promotes more eco-friendly practices in the industry.

This research paper aims to replace the ecologically harmful sodium dithionite traditionally used in the indigo dyeing process with the iron (II) gluconate reducing agent. The density functional theory (DFT) method using the B3LYP 6-311 G(d,p) basis set was used to determine the optimized structures of iron(II) gluconate and indigo. The highest occupied molecular orbital (HOMO) energy and the lowest unoccupied molecular orbital (LUMO) energy were calculated, and the electronic properties dependent on HOMO-LUMO energies were determined. Furthermore, an ecological dyeing process using this reducing agent was studied. The influences of alkalinity, reduction temperature, and iron(II) gluconate concentration on the fulfillment of the dyeing process were inspected by measuring the obtained redox potential and the color strength of the dyed samples. A full factorial experiment was performed for statistical analysis and optimization of the dyeing process. The results revealed that the developed method is highly effective and capable of generating redox potential and dyeing quality comparable to those obtained with the conventional process employing sodium dithionite. Finally, the substitution of sodium dithionite with iron (II) gluconate reduced the wastewater load generated by the conventional dyeing process.