Analysis of plasma plume parameters in physio-chemical processes of RF plasma jet plume direct in water for the inactivation of Enterococcus bacteria

The contamination of Enterococcus bacterium is widely observed in the living environment and water. The decontamination of drinking water from the bacterial pollution is an important issue in water treatment. Here, the inactivation of Enterococcus bacteria is studied by placing the dielectric barrier discharge structure, with the RF discharge frequency of 13.56 MHz atmospheric pressure argon plasma jet, directly in water, whereas the water around the plasma plume was seething and the bubbles produced stirring all liquid volume. The ability to place a plasma jet nozzle directly in water for 10 min while maintaining a steady and uniform plasma plume, besides water temperature, provides the effectiveness enhancement in the inactivation of bacteria. The absorption of UV radiation in water is effective, and the role of UV radiation of plasma plume was mainly responsible for the destruction of peptidoglycan, which is the outer layer of Enterococcus. Then, the presence of electrons and plasma plume in water leads to the formation of hydroxyl, hydrogen peroxide, and other reactive radicals that are involved in chemical reactions, which lead to the inactivation of micro-organisms. The number of bacteria decreases from the initial value of 16 × 105 MPN/100 ml to less than 1.2 MPN/100 ml. The spectra of the plasma radiation, with the plume length 2 cm within the water, have been analyzed via the first nitrogen negative system N2+B−X. The plume temperature was calculated to be about 64 °C, which has a good agreement with water temperature measured by using a thermometer at about 67 °C after 15 min at maximum 200 W input power of the plasma jet

Performance evaluation of pre-fabricated footing using cold-formed steel of lipped C-channel section

Conventional pad footing with temporary formwork using plywood or timber is not environmentally friendly and does not contribute to the strength of the foundation. This paper proposed the use of cold-formed lipped channel sections in pre-fabricated pad footings to increase the load capacity and speed up the construction time in addition to the reduction in timber used as the formwork, which leads to eco-friendly construction. An experimental investigation on the proposed pad footing was carried out in this study. Twelve specimens were made and tested with the axial compression force applied to the footing through the column stump to investigate the failure criterion of the footing due to cracks, overall deformation, and load-carrying capacity. All notable failures on the footing specimens were carefully observed and reported. The findings from the experimental investigations revealed a reasonable agreement with the theoretical models calculated based on CEN-EC2. The pre-fabricated composite pad footing demonstrated significant increment in strength as the footing was strengthened using steel sections, instead of steel bar, in comparison with that of conventional pad footing. The study revealed that the proposed pad footing system has the potential to be used as a structural component in mid-rise light-framed steel structures

Effects of waste ceramic as cement and fine aggregate on durability performance of sustainable mortar

In the last 3 decades, the attention in consuming substitute materials such as solid wastes in construction has grown continuously. An extensive amount of waste ceramic is being generated all around the world. These wastes are mostly sent to the landfill without considering recycling option. Such waste ceramic in the powder and fine particle forms has good potential in the infrastructure industry. In this study, the strength and durability properties of a mortar comprising ceramic waste powder as supplementary cementing material and ceramic particles were investigated. Properties studied include workability, compressive and tensile strengths, chloride and sulfate resistance. The effect of waste ceramic was also assessed by using scanning electron microscopy and X-ray diffraction analysis. It was observed that the utilization of waste ceramic in both forms of binder and fine aggregate significantly improved the compressive and splitting tensile strengths and higher resistance against chloride and sulfate attacks. The microstructure of the mortar was further enhanced by replacing ceramic waste powder and fine aggregates. It, therefore, caused in the higher crystalline formation and reduction in porosity and cracks in addition to eliminating the spalling behavior of mortar specimens exposed to chloride and sulfate attacks