This paper aims to study the radiation shielding characteristics and buildup factor of some types of granite in Egypt. The mass attenuation coefficient (MAC) for three types of granite (gandola, white halayeb, and red aswani) was experimentally determined, and the experimental results were validated by XCOM software. The relative deviation between the two methods does not exceed 3% in all discussed granite samples, which means that MAC calculated through the experimental and XCOM are in suitable agreement. The effective atomic number (Z_eff) varies from 13.64 to 10.69, 13.68 to 10.59, and 13.45 and 10.66 for gandola, white halayeb, and red aswani, respectively. As well as the equivalent atomic number (Z_eq) was calculated in a wide range of energy to deduce the exposure (EBF) and energy absorption (EABF) buildup factors for the studied granite materials. The linear attenuation coefficient (LAC), half-value layer (HVL), mean free path (MFP) were calculated at each investigated energy and showed that the most effective shielding ability at high energy was red aswani, while at low energy, the shielding ability was nearly constant for studied granites. The present study forms the first endeavor to obtain the radiation shielding properties of the studied materials to be used in practical applications.

Highly effective AgNPs@C was efficiently synthesized by electrical arc powered by single spark unit which was sufficient to ionize the dielectric media (deionized water) through applying strong electric field between the electrodes (silver and carbon). The AgNPs@C shell was characterized in terms of stability, morphology and phase structure. All characterizations showed that the prepared silver nanoparticles were spherical with average size reached 17 nm coated with carbon shell. The antibacterial effect of the synthesized nanoparticles was tested against Pseudomonas aeruginosa in comparison to Ceftazidime (commonly used antibiotic against P. aeruginosa infections). It was revealed that AgNPs@C shell has superior activity with inhibition zone diameter reached 15 mm and minimum inhibitory concentration reached 2 µg/mL. The observed activity was further confirmed by confocal microscope which showed an increased red region, representing the dead cells, correlated with the presence of AgNPs@C. Moreover, transmission electron microscope studies implied the possible AgNPs@C antibacterial mechanism of action was the nanoparticles adherence to the bacterial membrane causing cell lysis. The molecular studies against fimH (virulence adhesion gene), rmpA (mucoid factor encoding gene), and mrkA (biofilm forming gene) proved the inhibition of their genetic expression. The cytotoxic effect of the synthesized AgNPs@C showed CC50 reached 235.5 μg/mL against normal lung cells (L929 cell line).

A promising rotating arc discharge method has been developed for producing high purity silver carbon nanotube and zinc oxide nanoparticles, to study their capacities for methylene blue (MB) dye removal under different conditions such as contact time, initial methylene blue dye ion concentration, solution pH, and adsorbent dose. The equilibrium isotherm data were analyzed using Langmuir, Freundlich, Temkin isotherms. Correlation coefficients indicated the following order to fit isotherms for silver carbon nanotube: Freundlich > Langmuir > Temkin. On the other hand, for zinc oxide nanoparticles, the following adjustment founded to fit isotherms was: Langmuir > Temkin> Freundlich. Furthermore, separation factors and distribution coefficients of Methylene blue (MB) dye were calculated. Adsorption kinetic data were analyzed using pseudo-first and second -orders and Elovich model. Film and intraparticle Diffusion model were used to investigate Adsorption mechanism. Kinetic studies showed that the adsorption of methylene blue onto silver carbon nanotubes followed Elovich kinetic model, and the rate of adsorption is controlled by the liquid film diffusion model. Adsorption of methylene blue on zinc oxide nanoparticles followed the pseudo-second-order kinetic model, and the rate of adsorption is controlled by the intraparticle diffusion model.

A new type of nano-adsorbent zinc-silver nanoparticles ornamented by multi-walled carbon nanotubes (Zn-Ag MWCNT) was efficiently synthesized by double arc discharge using a newly designed rotating cylinder electrode. Zn-Ag MWCNT was characterized by different instrumental methods to get information about the sample shape, size, and crystallinity. Without irradiation, Zn-Ag MWCNT indicated significant potential for elimination against methylene blue (MB) which is dissolved in deionized water. When the adsorbent concentration was 0.1 g/L at normal 8 pH, the Zn-Ag MWCNTs were efficient in removing 97% of the MB from 40 mg/L that was dissolved in water for 10 min. The dye removal activity of (Zn-Ag) decorated MWCNTs was attributed to the influence of silver and zinc nanoparticles on the MWCNTs. Finally, this approach was both cost-effective and efficient.