The University of Zakho (UoZ) is located in Zakho, the Duhok Governorate, Iraqi Kurdistan, northern Iraq.
Diels–Alder (DA) cycloadditions are potent atom-economical transformations for the formation of six-membered cycloadducts with excellent regio- and stereoselectivity. The DA 4 + 2 cycloaddition between furan-2-ylmethanol and N-phenylmaleimides with para-substituents (X = H, F, Cl, Br) is studied using MEDT and density functional theory calculations at the M06‑2X(D3)/6‑311G(d,p) level. The polarity of the studied cycloaddition reaction was determined using conceptual DFT (CDFT) indices, natural population analysis (NPA), and global electron density-transfer (GEDT) values to quantify the electronic properties of the reagents and track the expected flow of electron density. In all substitution patterns, exo path is projected to be more favorable than endo path. The transition states’ polarity is corroborated by high GEDT values (≈ 0.26–0.28 e), showing electron density transfer from the furan-derived diene to the maleimide framework. Electron localization function (ELF) topological analysis for reactants and transition states was combined with bonding evolution theory (BET) along intrinsic reaction coordinates (IRC) to better understand chemical bond formation and how substituents affect it. These analyses suggest a two-stage, one-step (asynchronous) cycloaddition in which the new C–C bond is formed earlier at the transition state than the second bond involving the heteroatom-containing fragment, indicating a polar, nonsynchronous bonding reorganization rather than a perfectly coordinated event. Additional QTAIM and NCI descriptions show developing interactions at the forming bond critical points and weak stabilizing noncovalent contacts that favor exo transition structures. Electron-withdrawing substituents enhance electrophilicity of dienophile and subtly modulate energetics and electron density redistribution along the exo path, explaining the impact of phenyl-ring halogen substitution.
Co-contamination of paddy soils with antimony (Sb) and nickel (Ni) poses significant risks to soil quality, crop productivity, and food safety. This study evaluated the effectiveness of iron-titanium oxide-engineered biochar (Fe-Ti-BC) in mitigating Sb and Ni mobility in contaminated paddy soil and examined associated changes in soil carbon dynamics and microbial communities. Compared with the control, Fe-Ti-BC application reduced CaCl2-extractable Sb and DTPA-extractable Ni by 20.31-34.31% and 39.87-79.67%, respectively. Amendment with Fe-Ti-BC and unmodified biochar enhanced the carbon pool management index (CPMI) and labile organic carbon fractions, indicating improved carbon sequestration potential and nutrient cycling capacity. Rice biomass significantly increased following biochar treatments. Iron and titanium concentrations in root Fe plaque were approximately 20-fold and twofold higher, respectively, in Fe-Ti-BC-amended soils than in the control, suggesting enhanced plaque-mediated immobilization of trace elements. Consequently, Sb and Ni concentrations in rice grains decreased by 20.02-78.18% and 60.17-69.79%, respectively. High-throughput sequencing revealed that Fe-Ti-BC reshaped soil bacterial community composition and metabolic activity, promoting keystone taxa including Actinobacteria, Proteobacteria, and Firmicutes. Partial least squares path modeling (PLS-PM) identified CaCl2-extractable Sb, DTPA-extractable Ni, and Fe-Ti plaque formation as key determinants governing trace element accumulation in rice grains. Overall, Fe-Ti-BC effectively stabilized Sb and Ni through coupled geochemical and biological mechanisms, thereby reducing metal transfer to edible tissues while enhancing soil carbon functionality and productivity. These findings highlight the potential of engineered biochar as a sustainable remediation strategy for multi-metal contaminated paddy systems with direct implications for environmental health and food security.
This study investigates the fabrication and characterization of microwaves assisted Bismuth-doped graphitic carbon nitride (Bi@g-C3N4)composite into TiO2 as a photoanode material, for dye-sensitized solar cells (DSSC). The effect of Bi@g-C3N4/TiO2 was evaluated through photovoltaic performance measurements, revealing significant increases in power conversion efficiency (PCE) from 2.70
This paper investigates the Lie symmetry structure, conservation laws, and novel soliton solutions of a nonlinear Schro & uml;dinger equation. We determine the admitted Lie point symmetries and establish the associated Lie algebra generated by Gamma(1 )= partial derivative(x), Gamma(2) = partial derivative(t), and Gamma(3) = x partial derivative(x) +2t partial derivative(t). The algebraic structure is explored through the commutator table, adjoint representation, and classification of the optimal system of subalgebras. Corresponding similarity reductions transform the PDE system into reduced ordinary differential equations, for which approximate solutions are constructed using power series methods. In addition, conservation laws are systematically derived via conservation theorem, linking the symmetries to physically meaningful invariants. Novel soliton solutions have been established using the modified generalized Riccati equation mapping method (MGREMM). The results provide a comprehensive symmetry-based framework for the system under study, contributing to the broader understanding of nonlinear coupled PDEs and their analytical properties.
In this study, we investigate the cubic-quartic resonant nonlinear Schrödinger equation (CQRNSE) under a parabolic law to obtain various categories of optical solutions, including bright, dark, singular soliton, rational wave and singular periodic wave solutions. The CQRNSE describes wave propagation in fiber optics. The modified F-expansion method is a powerful technique employed to construct these solutions. Additionally, using bifurcation theory, we derive the associated Hamiltonian function and analyze the corresponding phase portraits. To graphically illustrate and exhibit the obtained solutions, we present them in both 3D and 2D formats. Furthermore, Poincaré sections and bifurcation diagram are used to analyze periodic, quasi-periodic, and chaotic behaviors of the related dynamic system, along with the system’s sensitivity to initial conditions. The findings of this research are fascinating and make a significant contribution to the domain of solitons in particular, and to the broader field of mathematical physics. The approach used in this work yields a variety of new solitary and soliton wave solutions, which will be valuable for researchers applying these models to real-world problems.
