An ab initio DFT perspective on experimentally synthesized CuBi2O4.

Here we present a comprehensive density functional theory (DFT) based ab initio study of copper bismuth oxide CuBi2O4 (CBO) in combination with experimental observations. The CBO samples were prepared following both solid-state reaction (SCBO) and hydrothermal (HCBO) methods. The P4/ncc phase purity of the as-synthesized samples was corroborated by Rietveld refinement of the powdered X-ray diffraction measurements along with Generalized Gradient Approximation of Perdew-Burke-Ernzerhof (GGA-PBE) and the Hubbard interaction U corrected GGA-PBE+U relaxed crystallographic parameters. Scanning and field emission scanning electron micrographs confirmed the particle size of the SCBO and HCBO samples to be ∼250 and ∼60 nm respectively. The GGA-PBE and GGA-PBE+U derived Raman peaks are in better agreement with that of the experimentally observed ones when compared to local density approximation based results. The DFT derived phonon density of states conforms with the absorption bands in Fourier transform infrared spectra. Both structural and dynamic stability criteria of the CBO are confirmed by elastic tensor and density functional perturbation theory-based phonon band structure simulations respectively. The CBO band gap underestimation of GGA-PBE as compared to UV-vis diffuse reflectance derived 1.8 eV was eliminated by tuning the U and the Hartree-Fock exact-exchange mixing parameter αHF in GGA-PBE+U and Heyd-Scuseria-Ernzerhof (HSE06) hybrid functionals respectively. The HSE06 with αHF = 14% yields the optimum linear optical properties of CBO in terms of the dielectric function, absorption, and their derivatives as compared to that of GGA-PBE and GGA-PBE+U functionals. Our as-synthesized HCBO shows ∼70% photocatalytic efficiency in degrading methylene blue dye under 3 h optical illumination. This DFT-guided experimental approach to CBO may help to gain a better understanding of its functional properties.

Influence of Y3+ and La3+ ions on the structural, magnetic, electrical, and optical properties of cobalt ferrite nanoparticles.

In the current study, nanocrystalline CoY0.5xLa0.5xFe2-xO4 (where x = 0.00, 0.02, 0.04, 0.06, 0.08, and 0.10) ferrites have been synthesized via a sol-gel auto combustion process. The synthesized powders were pressed into pellet forms and sintered at 900 °C for 4 h in the air. X-ray diffractometry (XRD) confirmed the single-phase cubic spinel structure of the synthesized samples having the mean crystallite domain sizes ranging from 122 and 54 nm. FTIR spectroscopic analyses revealed two strong bands within the range of 600 to 350 cm-1, further confirming the cubic inverse spinel structure of the prepared materials. The surface morphologies and composition were investigated by Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) Spectroscopy. The magnetic hysteresis curves recorded at room temperature exhibit ferrimagnetic behavior. The highest coercivity (Hc∼1276 Oe) was found at a high doping (x = 0.10) concentration of Y3+ and La3+ in cobalt ferrite. Dielectric constant increase with increased doping concentration whereas real-impedance and dielectric loss decrease with increased in doping concentration and applied frequency. The band gap energy increased from 1.48 to 1.53 eV with increasing Y3+ and La3+concentrations in the UV-Vis region. The elevated levels of magnetic and dielectric substances in the ferrite nanoparticles suggest that the material could be used for magnetic recording media and high-frequency devices.

Accumulation of Heavy Metals in Long-Evans Rat Through Feeding Fishes of Buriganga River and Their Histopathological Evaluation.

The study was conducted to evaluate the impacts of industrial discharges, including from tanneries, in terms of heavy metal loads in fin-fish of the Buriganga river, Dhaka, Bangladesh, and to find out the ultimate effects of feeding those heavy metal-contaminated fishes to Long-Evans rats to examine rats' heavy metal accumulation along with viable architectural alterations on various organs through histopathological screenings. Being the most edible by the populace, Labeo rohita was chosen for this purpose. Labeo rohita was collected from five different spots in the river close to the industrial outlets, covering three seasons: monsoon, winter, and summer throughout the year. Experiments unearthed that the deposition of heavy metals inside fishes always surpassed the standard margin, implying a pernicious aquatic milieu. The empirical data suggests that the mean concentrations of Cu, Pb, Cr, and Cd were higher than the permissible limits of WHO and FAO after feeding heavy metal-contaminated fishes for a period of 120 days. Seasonal variations were also taken into account, and it was noticed that rats fed with fish collected in winter had the highest heavy metal concentrations (P < 0.05). Significant architectural changes were observed during histopathological screening of rats' livers and kidneys characterized by necrosis, inflammation, and congestion. After gauging the obtained data, it might be concluded that consumption of heavy metal-contaminated fish entails accumulation of heavy metals, which causes histopathological changes in rats' livers and kidneys, including necrosis and severe structural deformational changes compared to those of control groups.

Phytochemical-Assisted Synthesis of Fe3O4 Nanoparticles and Evaluation of Their Catalytic Activity.

In this study, magnetite nanoparticles (Fe3O4 NPs) were synthesized using Baccaurea ramiflora leaf extracts and characterized by visual observation, UV-Vis, FTIR, XRD, FESEM, and EDS. The UV-Vis spectrum showed continuous absorption at 300-500 nm, confirming the formation of Fe3O4 NPs. FTIR revealed that compounds containing the O-H group act as reducing agents during Fe3O4 NPs formation. Agglomerated spherical NPs were observed in the FESEM image. The prominent peak at ~6.4 keV in the EDS spectrum ascertained the existence of Fe, while the sharp peak at ~0.53 keV confirmed the presence of elemental oxygen. XRD patterns affirmed the crystalline nature. The size of as-synthesized NPs was observed to be 8.83 nm. The catalytic activity of Fe3O4 NPs for the reduction of methylene blue (MB) dye was monitored by UV-Vis. The maximum absorption peak of MB dye at 664 nm was almost diminished within 20 min, which revealed Fe3O4 NPs could be an excellent catalyst for wastewater treatment.

Phytochemical Profiling, Antioxidant Activity, and In Silico Analyses of Sterculia villosa and Vernonia patula.

Our study aims to evaluate the chemical profiles and antioxidant activities of a methanolic extract of Sterculia villosa bark (MESV) and a methanolic extract of the Vernonia patula whole plant (MEVP). The chemical profiling of MESV and MEVP was performed via gas chromatography-mass spectrometry (GC-MS), which identified 52 and 33 chemical compounds, respectively. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay indicated that both MESV and MEVP displayed concentration-dependent scavenging activities, and half-maximal inhibitory concentration (IC50) values for MEVP, MESV, and ascorbic acid were 305.30, 555.44, and 36.32 µg/mL, respectively. The total flavonoid content (TFC) and total phenolic content (TPC) of MESV were 81.44 ± 2.70 mg quercetin equivalents (QE)/g dry extract and 62.58 ± 1.93 mg gallic acid equivalent (GAE)/g dry extract, whereas these values for MEVP were 291.31 ± 6.61 mg QE/g dry extract and 58.99 ± 3.16 mg GAE/g dry extract, respectively. Molecular docking studies were also evaluated, and absorption, distribution, metabolism, and excretion (ADME) and toxicological properties were assessed. Therefore, these two plants, S. villosa and V. patula, showed potential options for further advanced studies into oxidative stress.

Assessment of Heavy Metal Concentration in Water, Sediment and Common Fish Species of Dhaleshwari River in Bangladesh and their Health Implications.

The present study emphasized on evaluating the extent of pollution of Dhaleshwari River in Bangladesh due to the discharge of heavy metals from tanneries and other industries along with the health risks associated with the consumption of the heavy metals accumulated fish. For this purpose, three spots of Dhaleshwari River which are in the vicinity of the industrial outlet were selected for evaluating the seasonal status of heavy metals in water, sediment, and organs of three common fish species. Average concentrations of metals in water and sediment were in the order of Cr > Cd > Pb > Cu > As and Cr > Pb > Cu > As > Cd respectively. The average HM concentrations in water and sediment exceeded WHO and USEPA standards suggesting serious pollution to the aquatic environment. In fish organs, metal concentrations were in the order of Cu > Cr > Pb > Cd > As. Accumulation was highest in gills and lowest in muscles. Fish muscles had a relatively higher concentration of heavy metals (except As) exceeding the safe limits of FAO and WHO. Seasonal variation was also observed in water for all metals (p < 0.01), in sediment for Cu and As (p < 0.05), and in fish for Cr, Cd, and Cu (p < 0.05); higher concentrations were observed in winter. Bioconcentration factor analysis indicated that Cu, Pb, and Cr were more concentrated in fish. Health risk assessment reveals that the carcinogenic risk of Cr is associated with the consumption of contaminated fish species of the studied area.