Structural,Electrical, and Magnetic Properties of Ferrite–Polymer Composites

Six samples consisting of polypyrrole (PPy), pure NiFe₂O₄ ferrite, and their composites at ratio of 1:4 (PF1), 1:2 (PF2), 3:4 (PF3), and 1:1 (PF4) have been prepared by a coprecipitation method and their structural, electrical, dielectric, and magnetic properties measured experimentally. The direct-current (DC) resistivity was enhanced with increasing ferrite content, while the dielectric constant and loss decreased. The magnetic properties of all the composites and the ferrite revealed a narrow loop, confirming their soft nature. The saturation magnetization, remanence, and coercivity values increased with increasing ferrite content. The obtained parameter values suggest that such materials might be suitable for use in high-frequency applications.     

Mn1-xCuxO2/ reduced graphene oxide nanocomposites: Synthesis,characterization, and evaluation of visible light mediated catalytic studies

The narrow optical band gap, higher electrical conductivity, and wider-absorption range are three key features that a good photocatalyst must possess. Herein, we have fabricated Cu-doped MnO₂ (Mn_1-xCu_xO₂) nanostructure by facile wet chemical approach and formed its nanocomposite with r-GO (Mn_1-xCu_xO₂/r-GO) via ultra-sonication approach. The successful replacement of host metal ions (Mn⁴⁺) with the dopant metal ions (Cu²⁺) was supported with the PXRD, FT-IR, and EDX characterizations. The effect of Cu-doping on the band gap and r-GO matrix on the conductivity of the fabricated nanocomposite was also evaluated via Tauc plots and I–V tests, respectively. The photocatalytic efficiency of the fabricated photocatalysts was tested and compared against the methylene blue (MB) under visible light irradiation. The photocatalytic experiments revealed that Mn_1-xCu_xO₂/r-GO photocatalyst exhibited superior photocatalytic aptitude than that of pristine MnO₂ and Mn_1-xCu_xO₂ photocatalysts. More precisely, the Mn_1-xCu_xO₂ photocatalysts degraded 86.89% MB dye at the rate of 0.021 min^?1 after a 90-min exposure to the visible light. Observed superior catalytic activity of the nanocomposite can be attributed to the synergistic effects between the Cu doped MnO₂ and r-GO nanosheets that resulted in its narrow band-gap (2.19 eV) and excellent conductivity (2.217 × 10^?2 Scm^?1).     

Occurrence of aflatoxins in selected processed foods from pakistan

A total of 125 (ready to eat) processed food samples (70 intended for infant and 55 for adult intake) belonging to 20 different food categories were analyzed for aflatoxins contamination using Reverse Phase High Performance Liquid Chromatography (RP-HPLC) with fluorescent detection. A solvent mixture of acetonitrile-water was used for the extraction followed by immunoaffinity clean-up to enhance sensitivity of the method. The limit of detection (LOD) (0.01-0.02 ng·g(-1)) and limit of quantification (LOQ) (0.02 ng·g(-1)) was established for aflatoxins based on signal to noise ratio of 3:1 and 10:1, respectively. Of the processed food samples tested, 38% were contaminated with four types of aflatoxins, i.e., AFB1 (0.02-1.24 μg·kg(-1)), AFB2 (0.02-0.37 μg·kg(-1)), AFG1 (0.25-2.7 μg·kg(-1)) and AFG2 (0.21-1.3 μg·kg(-1)). In addition, the results showed that 21% of the processed foods intended for infants contained AFB1 levels higher than the European Union permissible limits (0.1 μg·kg(-1)), while all of those intended for adult consumption had aflatoxin contamination levels within the permitted limits.