Effects of implantation temperature and annealing on structural evolution and migration of Se into glassy carbon

Please read abstract in the article.The AST&D scholarship from the Tertiary Education Trust Fund (TETFund), Nigeria, and the Postgraduate Bursary from the University of Pretoria, South Africa.http://www.elsevier.com/locate/sssciehj2023Physic

Evaluating the antimicrobial activity and cytotoxicity of polydopamine capped silver and silver/polydopamine core-shell nanocomposites

Fabrication of bioactive nanomaterials with improved stability and low toxicity towards healthy mammalian cells have recently been a topic of interest. Bioactive metal nanomaterials such as silver nanoparticles (AgNPs) tend to lose their stability with time and become toxic to some extent, limiting their biological applications. AgNPs were separately encapsulated and loaded on the surface of a biocompatible polydopamine (PDA) to produce Ag-PDA and Ag@PDA nanocomposites to unravel the issue of agglomeration. PDA was coated through the self-polymerization of dopamine on the surface of AgNPs to produce Ag-PDA core-shells nanocomposites. For Ag@PDA, PDA spheres were first designed through self-polymerization of dopamine followed by in situ reduction of silver nitrate (AgNO3) without any reductant. AgNPs sizes were controlled by varying the concentration of AgNO3. The TEM micrograms showed monodispersed PDA spheres with an average diameter of 238 nm for Ag-PDA and Ag@PDA nanocomposites. Compared to Ag@PDA, Ag-PDA nanocomposites have shown insignificant toxicity towards human embryonic kidney (HEK-293T) and human dermal fibroblasts (HDF) cells with cell viability of over 95% at concentration of 250 µg/mL. A excellent antimicrobial activity of the nanocomposites was observed; with Ag@PDA possessing bactericidal effect at concentration as low as 12.5 µg/mL. Ag-PDA on the other hand were only found to be bacteriostatic against gram-positive and gram-negative bacteria was also observed.The University of Witwatersrand School of Chemistry, The University of the Witwatersrand Postgraduate Merit Award and the National Research Foundation of South Africa.https://www.journals.elsevier.com/arabian-journal-of-chemistryhj2023Physic

Design of palladium-conductive polymer electrocatalysts supported by graphene oxide for direct ethanol oxidation

M.Sc. (Chemistry)Abstract: Please refer to full text to view abstract

Optical and Morphological Properties of ZnO- and TiO 2

A microwave-assisted hydrothermal method was used to synthesize ZnO and TiO2 nanostructures. The experimental results show that the method resulted in crystalline monodispersed ZnO nanorods that have pointed tips with hexagonal crystal phase. TiO2 nanotubes were also formed with minimum bundles. The mechanism for the formation of the tubes was validated by HRTEM results. The optical properties of both ZnO and TiO2 nanostructures showed characteristics of strong quantum confinement regime. The photoluminescence spectrum of TiO2 nanotubes shows good improvement from previously reported data

Effect of Tb3+ concentration on the structure and optical properties of triply doped ZnAl2O4:1% Ce3+,1% Eu3+,x% Tb3+ nano-phosphors synthesized via citrate sol-gel method

Please read abstract in the article.The South African National Research Foundation (NRF) Thuthuka Programme (fund number: UID99266) and NRF incentive funding for rated researchers (IPRR) (Grant No: 114924). This work is based on the research supported in part by the NRF (R.E. Kroon, Grant Number 93214).http://www.elsevier.com/ locate/molstruc2020-01-05hj2019Physic

Associated aspects on structure, morphology and photoluminescence of MgAl2O4:x% Gd3+ nanophosphor prepared via citrate sol-gel method

Please read abstract in the article.The South African National Research Foundation (NRF) Thuthuka Programme (Fund No: UID99266) and NRF incentive funding for rated researchers (IPRR) (Grant No: 114924).http://link.springer.com/journal/116642020-06-01hj2019Physic

Multi-application of fennel (Foeniculum vulgaris) seed composites for the adsorption and photo-degradation of methylene blue in water

This work reports on synthesis of fennel-based composites and their feasibility to remove and photo-degrade methylene blue dye from aqueous solution. Pristine fennel seeds (PFS) was impregnated with iron(III) oxide nanoparticles (Fe2O3 NP) and iron(III)-1,2,3,4-tetracarboxylic acid (Fe-TCA) to yield the composites fennel seeds-nanoparticles (FS-NP) and fennel seeds-tetracarboxylic acid (FS-TCA), respectively. Scanning electron microscope (SEM) images revealed that the surface of the adsorbents appeared to have a rough texture with cavities. Fourier transform infrared spectroscopy (FTIR) spectra confirmed the presence of −OH, −C=O, −COC, −COOH and −CO groups that could easily bind to the dye. The physicochemical characteristics such as cation exchange capacity (CEC) and Brunauer, Emmett and Teller (BET) surface area were enhanced after impregnation compared with PFS. The maximum adsorption capacity recorded at pH 10 for PFS was 13.2 mg/g while for FS-NP and FS-TCA was 32.8 and 42.9 mg/g, respectively This was ascribed to chemical interaction such as hydrogen bond, electrostatic attraction and π-π stacking. The isotherm and kinetic data were best described by Freundlich and pseudo-first order models. Thermodynamic parameters (∆Ho and ∆Go) showed spontaneity and endothermicity respectively. The positive values of ΔSo suggests that there was increased level of freedom at solid/liquid interface. PFS showed no activity for photocatalytic degradation properties while PF-NP and PF-TCA recorded 58.9 and 48.6% efficiencies, respectively. The data revealed that pseudo-second order described the photocatalytic processes of MB better than pseudo-first order kinetics