http://archives.univ-biskra.dz/handle/123456789/57 2026-06-01T14:55:12Z http://archives.univ-biskra.dz/handle/123456789/33202 Titre: Monitoring physicochemical and biological characteristics of date palm waste compost Auteur(s): Ouali Abdelouahad Résumé: The date palm (Phoenix dactylifera L.) is an important crop in the MENA region, particularly in Algeria, where it is widely cultivated in areas like Biskra. This horticulture produces significant waste that needs to be recycled for sustainable development. Composting is a key method to recycle this agricultural waste, reducing reliance on chemical fertilizers and enhancing soil health. However, composting lignocellulosic wastes, like date palm waste (DPW), presents challenges due to its chemical properties that limit biodegradability. The current research utilized a cost-effective rotary drum bioreactor, which offers various advantages, to establish a decentralized system that enables farmers to manage waste effectively on their farms. Two compost preparation techniques were used. The first employed a ratio of 2:2:6 (DPW : Additives : Water) to achieve a moisture content of 60% , for 60 days composting, with poultry (PM1) and sheep manure (ShP2) as additives. The second approach accelerated decomposition by optimizing the initial moisture content and C:N ratio. A calculation technique was used to formulate a mixture with initial C:N ratios of 25 (CkS25) and 30 (CkS30), regarded as optimal for lignocellulosic composting by numerous studies, and included chicken litter as an additive for a 20-day period. To assist farmers with the mixture proportion calculations, an app was developed, taking into account their limited mathematics knowledge. In all trials, the bio-oxidation periods lasted 18 days, while the thermophilic phases lasted a minimum of 9 days. Throughout the trials, organic matter, moisture content, particle size, and wet bulk density showed a decreasing trend compared to their initial values, whereas other parameters exhibited an increasing trend. By day 20, all trial end products had a dark hue, a soil-like odor, and a low temperature. However, the germination index remained below the acceptable threshold for agricultural application (80%), with only the mixtures CkS25 and CkS30 recording a C:N ratios under 25. After 60 days, mixtures PM1 and ShP2 achieved a germination index around 80. In summary, the bioreactor and the mathematical approach proved effective in improving the initial mix; however, a 20-day period was insufficient for producing a fully mature and stable product. 2025-01-01T00:00:00Z http://archives.univ-biskra.dz/handle/123456789/31693 Titre: Synthesis and study of the dielectric properties of a doped NBT type material Auteur(s): Rahal Rahima Résumé: The present study reports the fabrication of NBT-type ceramic materials with the general formula (Na0.5Bi0.5) 0.94 R 0.04Ti 0.95 (Ni0.2 Fe0.2 Sb0.6) 0.05O3 (abbreviated as NBT-RNFS), where R denotes the dopant elements La, Nd, Gd, and Y. The ceramics were synthesized via the conventional solid state reaction method. The main objective of this study was to investigate the effect of rare earth doping on the dielectric and photocatalytic properties of novel NBT-based ceramic materials. The NBT-RNFS samples were successfully synthesized at 1150°C. Undoped NBT-NFS samples had a single rhombohedral phase, while rare earth-doped NBT-NFS samples showed a rhombohedral phase along with a pyrochlore phase. Rietveld refinement of the XRD data showed a slight shrinkage of the unit cell volume with the substitution of rare earth elements, attributed to their relatively lower ionic radii compared to the host ions. Optical bandgap analysis revealed that the fabricated perovskite samples exhibited semiconducting behavior, with measured bandgap values ranging from 2.61 to 2.80 eV. The La-doped NBT-RNFS system exhibited an impressive 83% photocatalytic dye degradation rate, substantially outperforming the 23% dye removal efficiency of the undoped material. Similarly, the Nd-doped (62% dye removal) and Y-doped (66% dye removal) NBT-RNFS ceramics also displayed enhanced photocatalytic activities under broadband solar light exposure. The La-doped NBT-RNFS composition demonstrated an exceptionally high dielectric constant (εr) of 1151.87, while the Nd-doped NBT-RNFS exhibited a dielectric constant of 1122.31. These values significantly exceeded the dielectric constant of 951.02 obtained for the undoped NBT-NFS ceramic. 2025-01-01T00:00:00Z http://archives.univ-biskra.dz/handle/123456789/31692 Titre: Études de différents modes d'interactions entre une cible neuro dégénérative et une nouvelle classe de molécules bioactives : Approches de Docking/Dynamique moléculaire, Replacement bioisostérique et ADME. Auteur(s): METTAI Merzaka Résumé: Monoamine oxidase B and adenosine A2A receptors are used as key targets in Parkinson's disease. The inhibitory power of a new series of phenylxanthine derivatives on two biological targets, the hMAO-B and hA2AR, has recently been demonstrated. Consequently, in our research work we carried out a study of the interactions established between 38 phenylxanthine derivatives with the biological targets hMAO-B and hA2AR. This study is based on the use of various molecular modeling techniques. A molecular docking study revealed that compounds L24 ((E)-3-(3-Chlorophenyl)-N-(4-(1,3-dimethyl-2,6- dioxo-2,3,6, 7-tetrahydro-1H-purin-8-yl) phenyl) acrylamide and L32 ((E)-3-(3-Chlorophenyl)-N-(3-(1,3 dimethyl-2,6-dioxo- 2,3,6,7-tetrahydro-1H-purin-8-yl)phenyl)acrylamide had a high affinity with the cavities of hMAO-B and hA2AR targets (S score: -10.160 and -7.344 kcal/mol respectively), and the stability of the complexes studied was confirmed through molecular dynamics simulations. A molecular electrostatic potential (MEP) analysis of compounds 24 and 32 was also carried out. In addition, the bioisosteric replacement approach was successfully applied to design two new analogues of each compound with low energy scores. Moreover, ADME-T and Drug-likeness results revealed promising pharmacokinetic properties and oral bioavailability for these compounds. Therefore, compounds L24, L32 and their analogues can be further analyzed and optimized to design new, more effective lead compounds for the treatment of Parkinson's disease. 2025-01-01T00:00:00Z http://archives.univ-biskra.dz/handle/123456789/31691 Titre: Synthèse et propriétés catalytiques d’oxydes mixtes à base de Néodyme et métaux de transitions Résumé: The goal of the project is to create strong and efficient oxygen evolution reaction (OER) electrocatalysts in order to address environmental pollution and energy scarcity. The sol-gel method was used to produce the perovskite NdFe1-xNixO3, and its electrocatalytic activity towards OER was evaluated. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and electrochemical techniques like linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronopotentiometry were among the methods used to characterize the prepared catalysts. The outcomes demonstrated that the NdFe1-xNixO3 compounds had a roughly spherical morphology and a pure orthorhombic crystal structure over the whole substitution range. The compounds were calcined at 800 ◦C. The calculated average diameters of crystallites are 19–24 ± 0.5 nm. The NdFe0.8Ni0.2O3 electrode, in particular, showed remarkable electroactivity, displaying lowest over potential (310 mV vs RHE) required to achieve a current density of 10 mA.cm−2, the lowest Tafel slope (149 mV.dec-1), and good stability over a 60-hour period, the NdFe0.8Ni0.2O3 electrode stood out for its exceptional electroactivity. These results offer insightful information about the development and design of high-performance electrocatalysts for uses in sustainable energy conversion and storage. 2025-01-01T00:00:00Z