Se⁴⁺ and N³⁻ ions were used as codopants to enhance the photocatalytic activity of TiO₂ under sunlight irradiation. The Se/N codoped photocatalysts were prepared through a simple wet-impregnation method followed by heat treatment using SeCl₄ and urea as the dopant sources. The prepared photocatalysts were well characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-diffuse reflectance spectroscopy (UV-DRS), scanning electron microscopy (SEM) and Raman spectroscopy. The codoped samples showed photoabsorption in the visible light range from 430 nm extending up to 580 nm. The photocatalytic activity of the Se/N codoped photocatalysts was evaluated by degradation of 4-nitrophenol (4-NP). The degradation of 4-NP was highly increased for the Se/N codoped samples compared to the undoped and single doped samples under both UV-A and sunlight irradiation. Aiming to determine the electronic structure and dopant locations, quantum chemical modeling of the undoped and Se/N codoped anatase clusters was performed using Density Functional Theory (DFT) calculations with the hybrid functional (B3LYP) and double-zeta (LanL2DZ) basis set. The results revealed that Se/N codoping of TiO₂ reduces the band gap due to mixing of N2p with O2p orbitals in the valence band and also introduces additional electronic states originating from Se3p orbitals in the band gap.

Histidine oligomers (His-tags) are commonly used as affinity tags in recombinant protein purification to enable in vitro experimental studies, including biochemical and biophysical assays and structure determination. His-tags enable protein purification by specifically and efficiently coordinating bivalent metal ions present in the purification resins, such as Cu2+, Zn2+, and Ni2+. Although His-tags, combined with Ni2+-based resins, are widely used due to their biophysical properties and commercial availability, the structure and nature of the metal cation coordination have remained unclear. In this study, the chemical structure of metal-coordinating His-tags was modeled to elucidate the metal preferences for better binding and to determine the structural changes that occur upon metal coordination. 6His-tag is a string of 6 histidine residues usually coordinated to bivalent metal ions (M2+), such as Ni2+, Zn2+, and Cu2+, through the nitrogen atoms of the imidazole rings. The metals complete their octahedral coordination shell with the lone pair of electrons of the oxygen atoms of the resin to which they are attached to. The resin was modeled as an oxalaldehyde group with the closed formula of (OCH)4. The geometry optimizations were carried out using the DFT method at the B3LYP/6-31g (d, p) level and in implicit water using the IEFPCM solvent model. The impact of Ni2+, Zn2+, and Cu2+ metals on the resin binding ability of 6His-tags was tested by adding amino acids to the N-terminus of metal-coordinated hexahistidine chains. The activity of the metals as electron donors or acceptors to the coordination bonds that they form was estimated by calculating the NBO energies. The complexation enthalpies of metal-bearing resin with hexahistidine, naked or having an amino acid tail, were calculated. Our results showed that Ni2+ has the highest affinity for the recombinant 6His-tag.

Water contamination is one of the most critical environmental issues, necessitating the development of effective wastewater treatment methods. The utilization of TiO₂ photocatalysts for pollutant removal in wastewater has gained significant attention. This study aims to explore the photocatalytic properties of TiO₂ modified through the introduction of different metal dopants, thus altering its electronic structure. Using the density functional theory (DFT) method, we examined the photocatalytic properties of TiO₂ clusters doped with metals carrying charges of +3, +4, and +5. Our findings indicate that the incorporation of these metals led to reduced energy and increased stability for the majority of TiO₂ clusters. The calculated UV-vis absorption results revealed that the wavelengths of Model B were extended further in the metal cation-doped TiO₂ clusters compared to Model A. Our DFT calculations demonstrated that the photocatalytic activity of the TiO₂ structure was enhanced upon doping with metals of +3, +4, and +5 valence.

Introduction: A large number of studies have been carried out for the etiology of atherosclerosis and many risk factors have been identified, including environmental factors and heavy metals, which are related to the pathogenesis. This study aimed to determine the effects of heavy metals, which have activation and inhibition effects on various metabolic pathways, on atherosclerosis by examining coronary arteries obtained from autopsy series. Methods: Coronary arteries of 28 autopsy cases were analyzed by inductively coupled plasma mass spectrometry method. Sixteen of the cases had coronary atherosclerotic plaques and 12 of the coronaries were normal. Twenty trace metal concentrations were examined from the samples obtained. Results: Twenty-eight coronary artery samples (16 with atherosclerosis, 12 normal) were analyzed using ICP-MS. Levels of Mg, K, Ca, P, Fe, Zn, Al, S, As, Pt, Sb, Hg were significantly higher in atherosclerotic arteries (e.g., Ca: 51,384 vs. 1,723 ppm, p = 0.005; P: 30,791 vs. 3,443 ppm, p = 0.003; Hg: 3.2 vs. 0 ppm, p < 0.001). Elements such as lead, cobalt, and cadmium remained below detection limits in both groups. Conclusion: Heavy metals through inflammation, oxidative stress, and disrupted antioxidant pathways are independent risk factors that increase the risk of atherosclerosis. These findings provide tissue-level evidence that heavy metal accumulation may contribute to atherosclerosis through oxidative stress, inflammation, and disruption of antioxidant defenses.