Pavement construction relies heavily on natural aggregates and conventional stabilizers such as Portland cement (PC) and lime, contributing to resource depletion, high energy demand, and significant greenhouse gas emissions. Geopolymerization, the alkaline activation of aluminosilicate materials, offers a more sustainable alternative. Mine tailings (MT), abundant mining by-products rich in silica and alumina, are attractive geopolymer precursors, although their reuse is constrained by variable composition and potential toxicity. In mining-intensive countries like South Africa, copper, cassiterite, and gold MT represent promising resources. This review critically synthesizes current knowledge on the physicochemical properties, mechanical performance, and environmental implications of geopolymerized MT in pavement applications. Unlike previous reviews that consider MT or geopolymers in isolation, it establishes a pavement-engineering–driven framework linking MT characteristics, geopolymer chemistry, and pavement performance requirements across laboratory, environmental, and field scales. The reviewed evidence indicates that MT-based geopolymers can achieve higher strength and superior durability than PC or lime-stabilized bases while reducing CO2 emissions by up to 80
Excessive consumption of synthetic food colourants such as tartrazine (TZ) poses significant health risks, highlighting the need for sensitive detection methods for food safety applications. Here, we report a binder-free electrochemical sensor based on synergistic integration of iron-based metal–organic framework MIL-100(Fe) with multiwalled carbon nanotubes (MWCNTs) on glassy carbon electrode (GCE). The nanocomposite leverages MIL-100's high porosity and accessible Fe3⁺ sites combined with MWCNT's superior conductivity, achieving an 11-fold enlarged electroactive surface area (0.786 cm2) and 19-fold enhanced exchange current density. Under optimized conditions using differential pulse voltammetry (DPV), the sensor exhibited a low detection limit (LOD) of 0.11 μM, a wide linear range (0.9 to 7.5 μM, R2 = 0.9891), and excellent selectivity over amaranth (AM) and common interferents. Mechanistic studies revealed adsorption-controlled, one-electron/one-proton irreversible oxidation with ultralow charge transfer resistance (0.073 kΩ). The sensor demonstrated robust performance with excellent repeatability (RSD = 2.11
We investigate a class of radiating star models with nonzero shear in general relativity by specifying a particular form of the gravitational potential associated with the areal 2-sphere. This choice enables the boundary condition equation to be transformed into a Riccati equation, which we integrate to obtain three distinct classes of exact solutions. These solutions represent a category of shearing metrics not previously studied. A comprehensive physical analysis confirms the physical plausibility of the solutions, highlighting their potential applicability to realistic radiating stellar structures.
This study investigated the acid rock drainage (ARD) potential of waste rocks (WR) in two abandoned mines in the Ekurhuleni region of the Gauteng Province, South Africa. ARD prediction characterization and techniques such as mineralogy, maximum potential acidity (MPA), net acid production potential (NAPP), acid neutralizing capacity (ANC), net acid generation (NAG) and biokinetic tests were performed to assess the ARD formation potential of the WR samples. WR-1 and 2 had sulphur contents of 0.34 and 2.3
Open access publishing has been promoted as a pivotal means of bridging the gap in knowledge access and usage. Despite the growing support for open access publishing globally, little is known about African scholars’ engagement with open access publishing and the barriers limiting their open access publishing practices. Using a survey research design, data was collected from 241 researchers from selected universities in Africa, such as Nigerian, Kenyan and South African universities. The data was collected using online surveys and analysed using the descriptive statistics of frequency counts and percentages. The study reveals that while most of the respondents had published open access articles (78.01%) and had a positive perception of the quality of open access journals (73.45%) and editorial teams, more than half were still limited by article processing charges (58.51%) as they had no funding for their research. Although African researchers are embracing open access publishing more now than they were historically, barriers such as article processing charges and the prolonged response time from reviewers continue to pose a serious challenge to open access uptake in Africa. This study proposes five recommendations for improving open access uptake in African and Global South countries.
