Jiwaji University

ACC deaminase is a pyridoxal phosphate-dependent enzyme that is highly prevalent in the plant-associated bacteria and fungi and is vital to the regulation of plant responses to abiotic stress. ACC deaminase reduces the stress-induced ethylene production, which otherwise suppresses plant growth and development. ACC deaminase degrade ACC, the immediate precursor of ethylene, into ammonia and 2-ketobutyrate. The acdS gene encodes the enzyme, which is highly regulated by complex transcriptional regimes containing regulatory elements including acdR (LRP family) and other related factors which respond to environmental factors. Evidence indicates that rhizobacteria with ACC deaminase activity increase root structure, nutrient uptake and salinity, drought, and heavy metal tolerance due to the coordinated hormonal regulation, antioxidant mobilization and rhizosphere interactions. Phylogenetic studies indicate that acdS is widely distributed among different bacteria and fungi. This study aims to discusses available knowledge, mechanism of action, genetics, distribution of ACC deaminase among various species, ecological role of ACC deaminase and, future research direction in developing transgenic plants through expression of foreign AcdS gene to survive biotic and abiotic stresses. ACC deaminase represents a key functional trait in soil–plant–microbe interactions with strong potential for sustainable agriculture, although further research is required to ensure reliable field-level applications.

We present a first-principles study of the structural, electronic, magnetic, thermodynamic and thermoelectric properties of the layered rare-earth nickelates Ce4Ni3O8 and Pr4Ni3O8 using the generalized gradient approximation (GGA)-Perdew–Burke–Ernzerhof (PBE) functional, modified Becke-Johnson (mBJ) functional, density functional theory with Hubbard U correction (DFT+U) and DFT with relativistic spin–orbit coupling (DFT+SOC) methods. The inclusion of on-site Coulomb interaction is essential to capture strong Ni-3d and Ce/Pr-4f correlations, leading to stabilization of a ferromagnetic metallic ground state, verified through total energy comparisons with antiferromagnetic configurations. The low-energy electronic structure is dominated by Ni-3d–O-2p hybridized states, while the rare-earth 4f states remain largely localized and are mainly affected by spin–orbit coupling. Thermodynamic properties are evaluated within the quasi-harmonic Debye model, indicating good lattice stability. Thermoelectric transport calculations using BoltzTraP2 show that ZT increases from 0.01 at 300 K to 0.16 at 900 K, consistent with correlated metallic behaviour. These results highlight the role of electronic correlations and magnetism in governing transport in Ce4Ni3O8 and Pr4Ni3O8.

We present a comprehensive density functional theory investigation of the layered rare-earth nickelates Sm4Ni3O8 and Eu4Ni3O8 to elucidate their structural, electronic, magnetic, and thermodynamic properties. Calculations were performed within the PBE-GGA framework, with electronic corrections introduced using the modified Becke Johnson (mBJ) potential and on-site Coulomb interactions treated through the DFT + U approach to accurately describe localized Ni-3d and rare-earth 4f electrons. Both compounds exhibit metallic behaviour, as confirmed by spin-resolved band structures without a band gap in either spin channel. Density of states analysis reveals strong Ni-3d-O-2p hybridization, while Sm-4f and Eu-4f states contribute significantly near the Fermi level, governing electronic transport and magnetic characteristics. Charge density analysis indicates stronger covalent bonding in Sm4Ni3O8, whereas Eu4Ni3O8 displays a more ionic nature. Magnetic moment analysis shows dominant contributions from rare-earth atoms, supported by moderate Ni moments. Thermodynamic properties were evaluated using the quasi-harmonic Debye model over temperatures from 0 to 900 K and pressures up to 50 GPa. The specific heat approaches the Dulong Petit limit at elevated temperatures, while increasing pressure enhances the Debye temperature and bulk modulus, indicating increased lattice stiffness. These results highlight the potential of these metallic layered nickelates for magnetic and thermoelectric applications.

Five novel transition metal complexes [Ni(H2aeth)2(Pic)2] (1), [Co(H2aeth)2(Pic)2] (2), [Ni(H2aeth)2(Pic)(HPic)] ClO4 (3), [Co(H2aeth)2(Pic)(HPic)]ClO4 (4) and [Zn(H2aeth)2 (Pic)(HPic)]ClO4 (5) were synthesized using a 2amino-5-ethylthio-1,3,4-thiadiazole (H2aeth) and picolinic acid (HPic) as co-ligands. These complexes were characterized by FT-IR, UV-Vis., X-ray photoelectron spectroscopy, TG-DTA, and single-crystal X-ray techniques. Crystallographic analysis confirmed distorted octahedral geometries around the metal centers with extensive hydrogen bonding networks promoting supramolecular assembly in the solid state. X-ray photoelectron spectroscopy (XPS), validated the +2 oxidation state of each metal center. Thermal studies indicated multistep decomposition processes resulting in the formation of metal oxides. Density functional theory (DFT) and timedependent DFT calculations were employed to explore electronic structures and predict UV-Vis. transitions, which showed good agreement with experimental data. Frontier molecular orbital (FMO) analysis revealed that Ni(II) complexes 1 and 3 are softer and more reactive, consistent with their observed biological activity. The anticancer potential of complexes 1-5 was evaluated in vitro using the MCF-7 human breast cancer cell line and the MTT assay. Complex 1 exhibited the strongest cytotoxicity (IC50 = 26.5 mu g/mL) followed by complexes 3 (34.9 mu g/mL), 4 (46.4 mu g/mL), 2 (81.1 mu g/mL), and 5 (103.3 mu g/mL). The observed activity trends correlate with metal identity and coordination environment, underlining the role of electronic and structural factors in modulating bioactivity. These findings suggest that thiadiazole-picolinate metal complexes, particularly those based on Ni (II), are promising scaffolds for anticancer drug development.

Materials deployed in nuclear fission and fusion environments experience extreme operating conditions involving high temperatures, intense neutron and ion irradiation, displacement damage and sustained thermomechanical stress. In this context, complex transition metal oxides with strong metal oxygen bonding and intrinsic lattice stability are of interest as potentially radiation tolerant functional materials. In this work, a systematic first principles investigation of the layered rare-earth nickelates Tb4Ni3O8, Dy4Ni3O8 and Ho4Ni3O8 is carried out using density functional theory within the full-potential linearized augmented plane wave method. Structural optimization and equation of state analysis confirm mechanically stable layered frameworks with relatively high bulk moduli and smooth energy volume behaviour, which are commonly employed as indicators of resistance to irradiation induced internal stress. Electronic structure calculations performed using GGA, modified Becke Johnson and GGA+U approaches consistently reveal a correlated metallic ground state arising from strong Ni-3d and O-2p hybridization, while localized rare earth 4f states primarily contribute to magnetic polarization without destabilizing the lattice. Thermoelectric transport properties evaluated within the semi classical Boltzmann framework exhibit stable temperature dependent electrical conductivity and finite Seebeck coefficients over a wide temperature range, indicating transport robustness against moderate disorder. Quasi harmonic Debye analysis further reveals smooth temperature and pressure dependent trends in heat capacity, Debye temperature, thermal expansion coefficient and Gr & uuml;neisen parameter, reflecting controlled lattice anharmonicity and thermodynamic stability. Overall, the present DFT based study provides essential baseline structural, electronic, transport and thermodynamic descriptors relevant for assessing the behaviour of layered rare earth nickelates under neutron and ion irradiated environments associated with advanced nuclear systems.