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This study explores the structural, mechanical, and photon attenuation properties of metakaolin-based geopolymers doped with bismuth oxide (Bi2O3) for potential photon and neutron attenuation applications. Geopolymer samples containing 0, 10, and 20 wt.
Acrylamide (AA) and 5-hydroxymethylfurfural (5-HMF) are heat-induced heterocyclic compounds with known carcinogenic and neurotoxic potential that are typically formed during thermal food processing. This study described the applicability of dispersive liquid–liquid microextraction (DLLME) method, coupled with high-performance liquid chromatography and UV detection (HPLC–UV), for the quantitative determination of AA and 5-HMF in Malaysian fried fish sausages (locally known as keropok lekor) samples. The separation was effected using a core–shell C18 column, isocratic elution with MeOH:H2O (10:90, v/v), resulting in a total run time of < 10 min. Detection wavelengths were set at 210 nm for AA and 280 nm for 5-HMF. The DLLME parameters were initially screened using a fractional factorial design to identify significant factors (sample volume, extractant volume, dispersant volume, and pH), followed by optimization using Box-Behnken design. The optimized DLLME conditions included 100 μL of chloroform (extractant), 500 μL of acetone (dispersant), and 5 mL sample volume adjusted to pH 5. The DLLME-HPLC–UV method demonstrated good linearity across the studied ranges (R2 = 0.9944 for AA and 0.9965 for 5-HMF), with detection limits (S/N = 3) of 10 µg L−1 for AA and 2 µg L−1 for 5-HMF. Intra- and inter-day precision showed relative standard deviations (RSDs) of ≤ 3.35
This study examines magnetohydrodynamic (MHD) heat and mass transfer of a ternary hybrid nanofluid over a rotating sphere incorporating thermophoretic particle deposition, thermal radiation, activation energy and chemical reaction effects. The nanofluid consists of Cu – Fe_3O_4 – ZrO_2 nanoparticles dispersed in propylene glycol. The governing boundary layer equations are transformed into a system of nonlinear ordinary differential equations via similarity transformations, which are solved using the Gegenbauer wavelet method. Results indicate that increasing magnetic interaction suppresses velocity due to Lorentz force effects while enhancing thermal distribution. Higher nanoparticle volume fraction improves heat transfer but increases viscous resistance. Thermophoresis and activation energy significantly influence mass transfer characteristics. Comparative analysis reveals that the ternary hybrid nanofluid exhibits enhanced thermal performance relative to the corresponding hybrid nanofluid configuration. The findings provide theoretical insight into MHD-controlled rotating nanofluid systems.
Interest in geopolymer concrete (GPC) made from agricultural wastes has increased due to the growing demand for environmentally friendly building materials; however, few studies have compared the short-term chemical resistance performance and optimisation of multi-source ash-based systems in harsh environments. The compressive strength, short-term chemical resistance, and optimisation of GPC made from sawdust ash (SDA), cassava peel ash (CPA), and rice husk ash (RHA), all of which have combined SiO₂ and Al2O₃ values greater than 70
The mechanical and microstructural responses of ordinary Portland cement (OPC) and one-part geopolymer concrete (OPGC) to fibre reinforcement have not been scientifically explored, hence generating a research gap. As more construction industries seek high-performance and ecologically friendly building materials, geopolymer concrete is becoming more popular as an alternative to OPC. Because it does not need liquid activators, a one-part geopolymer system is advantageous, and adding fibres increases its tensile and flexural strength. Despite these benefits, a comprehensive evaluation of its strength performance in comparison to conventional OPC concretes requires more research. Four concrete mixes, which are ordinary Portland cement (OPC), fibre-reinforced ordinary Portland cement (FROPC), one-part geopolymer concrete (OPGC), and fibre-reinforced one-part geopolymer concrete (FROPGC), are examined in this study for their fresh, mechanical, and micro-structural characteristics. Workability was assessed using slump tests, and at 7, 14, and 28 days, compressive, flexural, and split tensile strengths were measured. Stiffness, permeability, and internal quality were evaluated using the modulus of elasticity, water absorption, and ultrasonic pulse velocity (UPV), and microstructural examination was conducted using scanning electron microscopy (SEM). According to the findings, geopolymer concretes had better fresh qualities than OPC, with slump that were 20-31% higher. While fibre insertion greatly increased tensile and flexural strengths, it decreased workability. The highest compressive strength (63.78 MPa) was obtained by OPGC, whereas the highest flexural (15.1 MPa) and tensile (9.15 MPa) strengths were attained by FROPGC. Additionally, FROPGC showed the highest modulus of elasticity (44,040 N/mm2), and a refined microstructure with fewer vacancies and well-bonded fibres was shown in FROPC and FROPGC.
