Microwave- and Formaldehyde-Assisted Synthesis of Ag–Ag₃PO₄ with Enhanced Photocatalytic Activity for the Degradation of Rhodamine B Dye and Crude Oil Fractions

The release of crude oil and water-soluble dyes into our marine environment is a major global problem. An efficient semiconductor Ag–Ag3PO4 photocatalyst was synthesized using formaldehyde as a reducing agent to form surface active Ag on Ag3PO4 under microwave radiation for heating, and its potential in destroying environmental pollutants has been examined. The diffuse reflectance spectroscopy of Ag–Ag3PO4 revealed an enhanced absorption in the visible light region. The rate of photocatalytic degradation of rhodamine B by Ag–Ag3PO4 was over 4-fold compared to Ag3PO4. The potential application of Ag–Ag3PO4 in oil spill remediation was also examined through photocatalytic degradation of benzene, n-hexane, and 1:1 v/v benzene/methanol crude oil-soluble fractions. UV–vis and gas chromatography–mass spectrometry analysis of the crude oil components after visible light irradiation showed excellent degradation. The photocatalytic efficiency enhancement of Ag–Ag3PO4 is attributed to the excellent electron trapping of silver nanoparticles deposited on the surface of Ag3PO4. This work will motivate future studies to develop recyclable visible light photocatalysts for many applications

Electrochemical Response of Cells Using Bioactive Plant Isolates

Traditional herbal medical practices continue to be part of the healthcare needs of the world especially residents of sub-Sahara Africa (sSA). However, the mechanism of action of the plant metabolites to elicit their potency continue to be a mystery due to the lack of standardized methods. The mechanism of plant bioactive compounds to cause cell death is gradually being linked to membrane polarization and depolarization behaviour. The current work seeks to probe the electrochemical response of model cells using bioactive compounds captured in bio-zeolites or membrane mimetics. The voltage and current fluctuations emanating from such studies will establish a correlation between cell death and membrane depolarization. It will be a useful biological interface sensing material with the potential to identify plant metabolites that can selectively detect and destroy diseased cells. Several model membranes have already been developed for biomedical applications and this new paradigm will elevate the usefulness of these model systems. The concept was investigated using extracts from Dioclea reflexa (DR) hook which belongs to the leguminous family. There are certain class of compounds in Dioclea reflexa (DR) that have clinical usefulness in both temperate and tropical regions, however the identity of the bioactive compounds responsible for inducing cell death continue to be a major challenge

Comparative analyses of the mechanical and microstructural properties of the weld region of LPG cylinder materials

This paper presents the numerical and experimental results of the mechanical and microstructural properties of liquefied petroleum gas cylinders from local sources. The tensile strength, burst and fracture toughness of the materials were also investigated. The results show that the carbon content for all samples averaged ~0.22 wt% and manganese ~0.76 wt% and the microstructure was largely pearlitic. The tensile strength showed that LPG-C3 recorded high tensile strength of ~ 611 MPa and hardness of ~ 200 HV while LPG-C5 recorded low tensile strength of ~ 450 MPa. The finite element analysis (FEA) showed fracture toughness of ,5 105MPa.mm0.5 for LPG-C2 and the energy release rate of ~2 106J/m2 for LPG-C5. All samples exhibited high resilience to crack propagation which showed ductile fracture after tensile test. The implications of the results are discussed to elaborate on the influence of carefully controlling the alloying elements of LPG cylinder materials on their mechanical and microstructures during fabrication.The African Research Universities Alliance Early Career Fellowship (ARUA-ECRF), the University of Ghana BANGA-Africa Program, and the TWAS-DFG Fellowship.https://www.tandfonline.com/loi/oaen20am2024Materials Science and Metallurgical EngineeringSDG-09: Industry, innovation and infrastructur

The effect of synthesis route on the photocatalytic performance of Ag-TiO2 using rhodamine b dyes, pesticides, and pharmaceutical waste as model pollutants

The use of noble metal loading such as Ag to improve the photocatalytic performance of TiO _2 has been well studied. Though different synthesis methods have been used to synthesize Ag-TiO _2 nano-composite, the effect of the different synthesis routes on the photocatalytic performance has not been studied and compared. This study focusses not only on the enhancement of photocatalytic performance by the addition of Ag, but also on the influence of the synthesis process on photocatalytic performance. Two different routes: photodeposition (PD) and formaldehyde assisted microwave (MW) synthesis of Ag-TiO _2 nano-composite and their photocatalytic performance were evaluated using model pollutants. The Ag-TiO _2 were synthesized using different wt% (0.5, 1.0, 1.5 and 2.0 wt%) of Ag. The synthesized Ag-TiO _2 were characterized with x-ray diffractometer, scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and UV–vis spectrophotometry. The Ag-TiO _2 photocatalyst showed superior photocatalytic performance towards rhodamine b dye as compared to raw TiO _2 . 0.5 wt% Ag-TiO _2 -PD recorded the highest rate constant and degradation percent among the composites synthesized using photodeposition (PD) method. On the other hand, 1.0 wt% Ag-TiO _2 -MW performed better among the composites synthesized using microwave and formaldehyde assisted synthesis. The potential of these best performing composites; 0.5 wt% Ag-TiO _2 and 1.0 wt% Ag-TiO _2 to photocatalytically degrade pharmaceutical (Naproxen Sodium and Flurbiprofen) and pesticide (Atrazine and Pyrimethanil) pollutants were examined. These composites degraded the pollutants exceptionally well with 0.5 wt% Ag-TiO _2 -PD outperforming the 1.0 wt% Ag-TiO _2 -MW. 1H NMR and 13C NMR analysis revealed that the synthesized Ag-TiO _2 were effective in degrading the model pollutants

Capturing Dioclea Reflexa Seed Bioactives on Halloysite Nanotubes and pH Dependent Release of Cargo against Breast (MCF-7) Cancers In Vitro

In this work, optimization parameters were developed to capture plant metabolites from Dioclea Reflexa (DR) seed ex-tracts onto halloysites nanotubes (HNTs). A one-step pool of the crude extracts at neutral pH from the HNT lumen failed to elicit a reduction in breast cancer, Michigan Cancer Foundation-7 (MCF-7) cell viability. However, the pH-dependent elution of metabolites revealed that the acidic pH samples exhibited profound antiproliferative effects on the cancer cells compared to the basic pH metabolites using both trypan blue dye exclusion assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability test. pH~5.2 samples demonstrated by half-maximal inhibitory concentration (IC50) of 0.8 mg and a cyclic voltammetry oxidation peak potential and current of 234 mV and 0.45 µA, respectively. This indicates that the cancer cells death could be attributed to membrane polarization/depolarization effects of the sample. Fluorescence-activated cell sorting (FACS) studies confirmed that the plant metabolites affected breast cancer apoptotic signaling pathways of cell death. The studies proved that plant metabolites could be captured using simplified screening procedures for rapid drug discovery purposes. Such procedures, however, would require the integration of affordable analytical tools to test and isolate individual metabolites. Our approach could be an important strategy to create a library and database of bioactive plant metabolites based on pH values

Effect of Magnesium and Sodium Salts on the Interfacial Characteristics of Soybean Lecithin Dispersants

One of the most widely accepted oil spill response strategies is chemical dispersant application. However, since the surfactant used in their formulation may be ionic, its interfacial characteristics may be influenced by ions present in the sea. In this work, we have examined the effect of magnesium salts (MgSO₄ and MgCl₂) and sodium salts (NaCl, Na₂SO₄, and sodium benzoate) on the interfacial characteristics of hydroxylated soybean lecithin dispersant (H–PI). The oil-in-water emulsions formed with magnesium salts were more stable than those formed with sodium salts. Magnesium salts recorded the highest interfacial tension reduction and the highest dispersion effectiveness values when compared with sodium salts. These observations were attributed to (i) the Mg²⁺ ions interconnecting the negatively charged headgroups of H–PI at the oil-droplet–water interface, thus increasing the surface elasticity and viscosity, and (ii) the smaller ionic size of Mg²⁺ allowing for easy packing between the charged head groups of H–PI

Characterization and Inhibitory Effects of Magnetic Iron Oxide Nanoparticles Synthesized from Plant Extracts on HeLa Cells

Magnetic Fe3O4 nanoparticles were synthesized from maize leaves and plantain peels extract mediators. Particles were characterized, and the inhibitory effects were studied on HeLa cells in vitro using cyclic voltammetry (CV). Voltammograms from the CV show that Fe3O4 NPs interaction with HeLa cells affected their electrochemical behavior. The nanoparticles formed with higher Fe3+/Fe2+ molar ratio (2.8 : 1) resulted in smaller crystallite sizes compared to those formed with lower Fe3+/Fe2+ molar ratio (1.4 : 1). The particles with the smallest crystallite size showed higher anodic peak currents, whereas the larger crystallite sizes resulted in lower anodic peak currents. The peak currents relate to cell inhibition and are confirmed by the half-maximum inhibitory concentration (IC50). The findings show that the particles have a different inhibitory mechanism on HeLa cells ion transfer and are promising to be further exploited for cancer treatment

Capturing Dioclea Reflexa Seed Bioactives on Halloysite Nanotubes and pH Dependent Release of Cargo against Breast (MCF-7) Cancers In Vitro

In this work, optimization parameters were developed to capture plant metabolites from Dioclea Reflexa (DR) seed ex-tracts onto halloysites nanotubes (HNTs). A one-step pool of the crude extracts at neutral pH from the HNT lumen failed to elicit a reduction in breast cancer, Michigan Cancer Foundation-7 (MCF-7) cell viability. However, the pH-dependent elution of metabolites revealed that the acidic pH samples exhibited profound antiproliferative effects on the cancer cells compared to the basic pH metabolites using both trypan blue dye exclusion assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) viability test. pH~5.2 samples demonstrated by half-maximal inhibitory concentration (IC50) of 0.8 mg and a cyclic voltammetry oxidation peak potential and current of 234 mV and 0.45 µA, respectively. This indicates that the cancer cells death could be attributed to membrane polarization/depolarization effects of the sample. Fluorescence-activated cell sorting (FACS) studies confirmed that the plant metabolites affected breast cancer apoptotic signaling pathways of cell death. The studies proved that plant metabolites could be captured using simplified screening procedures for rapid drug discovery purposes. Such procedures, however, would require the integration of affordable analytical tools to test and isolate individual metabolites. Our approach could be an important strategy to create a library and database of bioactive plant metabolites based on pH values

Synthesis and characterisation of zeolite-A and Zn-exchanged zeolite-A based on natural aluminosilicates and their potential applications

Zeolites have been hydrothermally synthesized using alumina and silica based deposits (kaolin, bauxite, silica and feldspar) sampled from three regions in Ghana and the chemical compositions of the zeolites varied by batch formulations. The as-synthesized zeolites were characterized using X-ray Diffraction, Fourier Transform Infra-Red and Porosimetry techniques. The morphology and elemental compositions were examined using Scanning Electron Microscopy and energy dispersive X-ray spectroscopy (EDX). The results indicate that zeolite A was formed with a cubic structure and structural variations depending on the batch formulations. By increasing the silica content (Si/Al ratio) through batch formulations, the crystallite sizes of zeolites increased forming Zeolite A with LTA structure and Zeolite A (K-exchanged dehydrated). Samples with higher alumina content produced Zeolite A (Hydrated), Zeolite-Na and Zeolite A (Na, Dehydrated) with lower crystallite sizes. The zeolite synthesized was then used in the synthesis of zinc exchanged Zeolite A (Zn-zeolite A). EDX analysis confirmed a complete exchange of Na in the Zeolite framework with Zn and the feasibility as an adsorbent for methylene blue tested. The synthesized Zn-exchanged Zeolite A showed strong adsorption for methylene blue dye. The adsorption kinetics of the MB onto Zn-exchanged Zeolite A was observed to follow pseudo-second-order model. Freundlich model better described the interaction among adsorbate molecules onto the Zn-exchanged Zeolite A adsorbent, suggesting a multilayer distribution of adsorbate molecules with some level of interaction between adsorbed molecules. The regeneration capacity of the adsorbent was low and calculated to be about 48% at pH of 12