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Hydroxyapatites (HAps) synthesized from waste animal bones have recently gained attention due to their outstanding properties. This is because there is a need to fabricate scaffolds with desirable mechanical strength, ability to withstand high temperatures, and insoluble in solvents such as water, acetone, ethanol, and isopropyl alcohol. This study is an extensive summary of many articles on the routes of synthesis/preparation of HAp, and the optimum processing parameter, and the biomedical application areas, such as: drug administration, dental implants, bone tissue engineering, orthopedic implant coatings, and tissue regeneration/wound healing. A broad catalog of the synthesis methods (and combination methods), temperature/time, shape/size, and the calcium‐to‐phosphorous (Ca/P) value of diverse waste animal bone sources were reported. The alkaline hydrolysis method is proposed to be suitable for synthesizing HAp from natural sources due to the technique's ability to produce intrinsic HAp. The method is also preferred to the calcination method owing to the phase transformation that takes place at high temperatures during calcinations. However, calcinations aid in removing impurities and germs during heating at high temperatures. When compared to calcination technique, alkaline hydrolysis method results in crystalline HAp; the higher degree of crystallinity is disadvantageous to HAp bioactivity. In addition, the standardization and removal of impurities and contaminants, thorough biocompatibility to ensure clinical safety of the HAp to the human body, and improvement of the mechanical strength and toughness to match specific requirements for the various biomedical applications are the important areas for future studies. [ABSTRACT FROM AUTHOR]

Photovoltaics is the third-largest renewable energy source in the world today due to its popularity; however, thin-film solar cells are currently replacing PV due to material limitations in large-scale applications. These cells must be developed from widely accessible, fairly cost-effective, and environmentally benign materials. Silica nanoparticles derived from rice husk (SiO2np) and doped Cu2O thin films were examined for solar cell applications. A nebulizer spray technique was used to deposit SiO2np of 0.25, 0.5, 0.75, 1, and 1.25 wt% onto Cu2O. The electrical, optical, and microstructural properties of the deposited thin films were studied. The presence of SiO2np in the Cu2O phase was observed in the XRD spectrum. The structural, optical, and electrical properties of SiO2np: Cu2O thin films were highly affected by SiO2np doping. The energy bandgap and optical transmittance are reduced with a rise in SiO2np doping. An 84.61% and 98.85% increment in mobility and carrier concentration and a 33.87% and 72.72% decrease in band gap and resistivity were obtained at 1.25 w% SiO2np:Cu2O. It was established that SiO2np:Cu2O thin films produced 0.480% power conversion efficiency and 0.30 V open-circuit voltage. [ABSTRACT FROM AUTHOR]

High-voltage insulators were developed from CaCO3 derived from waste snail shell to replace the low-impact energy ceramic insulators. Taguchi-grey (GRA) multi-response analysis was experimentally used to assess the effects of the processing parameter. The multi-response variables chosen were the dielectric constant, water absorption, and impact energy. The findings show an optimal point of 15 wt% CaCO3-snail shell, 120 °C curing temperature, and 6 h of curing time. The anticipated GRA was quite close to the experimental GRA at a 95% confidence level. This proved the effectiveness of the best processing settings. It was established that waste snail shell could be used in the production of high-voltage insulators that can withstand voltages up to 13.5 kV with high ultraviolet radiation resistance. [ABSTRACT FROM AUTHOR]

This novel study investigated and proposes the use of Pycnanthus angolensis seed husk for the sequestration of Pb(II) from contaminated solutions, with the aim of contributing to the urgent need for accessibility to quality water, sustainable management of water and the environment in line with the Sustainable Development Goals (SDGs). The activated Pycnanthus angolensis seed husk was developed by modifying the pure sample (P-PA) with ethylene-glycol (E-PA) and Iso-butanol (I-PA). Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), the Brunauer-Emmett-Teller (BET) analyzer, thermogravimetric analyzer (TGA), and X-ray diffractometer (XRD) were used to characterize the adsorbents before and after adsorption. The batch adsorption studies carried out revealed the highest adsorption of Pb(II) at pH 6 and 180 min for all the adsorbents. The functional groups, as well as the shifts in peaks after modification, were confirmed using FTIR analysis. In addition, SEM images show a heterogeneous, rough surface with sufficient cavities of the adsorbent after modification. The physiochemical characteristics indicated that BET pore volume and pore diameter increased for E-PA and I-PA compared to P-PA. The experimental data obtained indicated that Langmuir and pseudo-first-order (PFO) best described the isotherm and kinetic models, respectively. The adsorption mechanism revealed that the adsorption of Pb(II) was controlled mainly by pore filling, while electrostatic interaction, surface complexation, and ionic exchange also occurred minimally. The thermodynamic parameters, ΔH° and ΔG°, suggest an endothermic and spontaneous adsorption process, respectively. The findings in this study indicate that Pycnanthus angolensis seed husks offer cost-effective and sustainable solutions that are readily accessible for wastewater treatment. [ABSTRACT FROM AUTHOR]

The surface hardening of mild steel by carburization using periwinkle shell nanoparticles (PWSnp) and coconut shell (CS) was investigated. The carburization was done at 850, 900, and 950 °C with a ratio of PWSnp:CS of 1:9, 2:8, and 3:7. The case depth, hardness values, wear, and corrosion rates were determined. A 114.1% increment in the hardness values, a corrosion protection efficiency of 92.58%, and a 45.67% wear resistance of the mild steel were obtained at 3:7 PWSnp: CS and 950 °C. The development of a passive layer that enveloped the sample and shielded it from further corrosion assaults was responsible for the excellent protection efficacy of the carburized sample. It was established that waste periwinkle shell and coconut shell can be used for surface hardening of mild steel. [ABSTRACT FROM AUTHOR]

High modulus of about 1 TPa, high thermal conductivity of over 3000 W/mK, very low coefficient of thermal expansion (CTE), high electrical conductivity, self-lubricating characteristics and low density have made CNTs one of the best reinforcing materials of nano composites for advanced structural, industrial, high strength and wear-prone applications. This is so because it has the capacity of improving the mechanical, tribological, electrical, thermal and physical properties of nanocomposites. So, this study is aimed at providing the latest discoveries on the tribological behavior of CNTs-reinforced composites. The composites reviewed included metal matrix composites (MMCs), polymer matrix composites (PMCs) and ceramic matrix composites (CMCs) reinforced with CNTs. Their tribological characteristics, uses, production challenges, conclusion and recommendations are presented. The work presented the best technique to disperse CNTs on matrices to avoid its agglomeration, since agglomeration is one of the major challenges in reinforcing with CNTs. It was discovered that ball milling destroys the outer walls of CNTs but recommended that ultrasonication and functionalization before ball milling eliminate this adverse effect of ball milling. In addition, it was discovered that addition of CNTs to composite matrices improved the wear resistance, reduced the wear volume, decreased the coefficient of friction (COF) and provided self-lubricating effect on MMCs, PMCs and CMCs. [ABSTRACT FROM AUTHOR]

High thermal conductivity and dielectric materials with enhanced electrical conductivity are needed in advanced electronics. However, simultaneous improvement in this material remains a challenge. Here, the synergistic effect of dielectric materials and the high thermal conductivity of epoxy-carbon nanotube decorated with waste eggshell through the Taguchi-Grey experiment have been studied to achieve this challenge. The composite was produced by the solution stirring method. The dielectric constant, thermal and electrical conductivity, and morphology of the samples were evaluated. The optimal condition of the composite for higher electrical and thermal conductivity was obtained at 1wt%ESp, 2.5wt%CNTs, 90oC curing temperature, and 6 hours of curing time with 19,130% and 94.27% increments in thermal and electrical conductivity. The predicted grey relational grade was close to the experimental grey relational grade at a confidence limit of 95%. This validated the efficacy of the obtained optimal processing parameters. It was established that waste eggshells can be used to ensure good dispersion of CNTs for the production of conductive polymers for improved electrical and thermal conductivity. [ABSTRACT FROM AUTHOR]

In the past, ceramic materials were exclusively used as transmission insulators for high voltage. However, due to the drawbacks of ceramic materials, including their heavy weight, challenging production, and poor toughness, high-voltage transmission insulators are now being replaced by polymeric materials. The majority of the issues with ceramic insulators are addressed by polymeric insulators. This study aimed to enhance the toughness and insulating properties of an epoxy composite developed SiO2 nanoparticles obtained from rice husk. The samples were produced by the solution stir cast method. The microstructure, impact strength, fracture toughness, and insulation properties of the developed composite were determined. The toughness and insulating properties that have been reported are within the acceptable range for high-voltage insulators. The developed composite insulator was found to be capable of withstanding voltages of up to 14.9 kV. The developed composite might be utilized to produce electrical insulators with great toughness and good insulating properties. [ABSTRACT FROM AUTHOR]

Electricity transmission is an essential intermediary linking power generation and distribution. Voltage drops or total blackouts have always characterized the transmission and distribution of electricity in the sub-Saharan Africa and some Asian dwellers. This has been attributed partly to faulty, defective or dilapidated transmission conductors/networks. The aim of this study is to identify the causes of those defects in the transmission conductors and proffer possible remedies to them. Studies have shown that the current production techniques of transmission conductors (TCs) generate defective products, and that the materials used have their own challenges too. This work, therefore, reviewed all the production techniques and materials used in the development of TCs. It was observed that pultrusion, extrusion, hot-rolling, and stir-casting were the techniques used in the production of transmission conductors. Defects such as shrinkage, pores, impurities, and warps were identified in those techniques and some recommendations to ameliorate the defects of those techniques were presented. Spark plasma sintering is recommended as the most promising solid- state production techniques that should be adopted in fabricating transmission conductors, though it is yet to be developed for producing long-span products. In addition, advanced TCs materials such as Al-CNTs, Al-Nb, Al-Ti, and Al-B2 were presented as better alternatives to the existing TCs materials. By producing TCs with the recommended techniques and materials, the electricity availability will be enhanced; and this will lead to sustainable industrial growth and economic stability in the third world countries and the entire world. [ABSTRACT FROM AUTHOR]

The demand for electricity has increased drastically due to population explosion globally. Unfortunately, supply does not meet the demand. Consequently, the transmission grid becomes overloaded, culminating in frequent power outages. Worse still, the transmission grid lacks adequate maintenance, and this has led to energy crisis in Africa and some parts of Asia. In this review, studies on the strength and weaknesses of existing transmission conductors were conducted. Further studied were natural and artificial phenomena that attack the overhead transmission networks. It was observed that besides inherent conductor defects, overloading, bush fire, short-circuit, harsh weather, and lightning were the factors that ravage the transmission grid. Hence, there is the need to develop more robust conductor materials that can withstand these challenges. The conventional conductors such as all aluminum conductor (AAC) and aluminum conductor steel reinforced (ACSR) are challenged by low operating temperatures, among others. High-temperature low-sag (HTLS) conductors that were invented to tackle these shortcomings certainly have higher ampacity and better thermal rating than the conventional conductors. However, some challenges still devastate them. So, from the study conducted, it was discovered that developing advanced nano-based Al-composite conductor would help in ameliorating the challenges prevalent in the transmission grid. Such an Al-nanocomposite conductor would possess higher ampacity and better thermal stability and would be more durable and cost effective. [ABSTRACT FROM AUTHOR]