Engineering and Technology Journal

In the current work, silver nanoparticles (Ag-NPs) were successfully synthesized via laser ablation while their hemocompatibility and antibacterial features were tested against dental decay bacteria. The silver bulk was immersed in cetrimonium bromide (CTAB) and focused by a pulsed Nd:YAG laser at 1064 nm, 600 mJ at room temperature, a pulse duration of 10 ns, and a repetition rate of 5 Hz. The obtained Ag-NPs suspension was systematically and comprehensively characterized by harnessing UV–Vis spectroscopy, zeta potential (ZP), Fourier transform infrared (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Results demonstrated that the absorption spectrum of Ag NPs colloidal solution was characterized by the peak observed at 425 nm. Meanwhile, The NPs XRD patterns revealed the presence of Ag phase planes (111), (200), and (220). All samples manifested aggregation-induced spherical nanostructures as disclosed by the FESEM images. Besides, the TEM images revealed nearly spherical NPs, with sizes ranging from 5–70 nm, for Ag NPs prepared with CTAB. The antibacterial activity against a clinical isolate of Streptococcus mutans was conducted at a wide spectrum Ag concentration range (0.0, 50, 75, 100, and 200) μg/mL. The in vitro hemocompatibility effects were obtained by measuring the hemolysis rate of red blood cells. Results reported that the antibacterial activity against Streptococcus mutans was size and concentration-dependent, and the hemolysis rate revealed low effects at low concentrations. Thus, Ag NPs could be a promising candidates to treat and prevent dental caries.

High chromium white cast iron (HCWCI) is used in mining, crushing plants, as mill liners, and in the manufacture of grinding balls. The grinding ball is the essential element in fine fragmentation. It must have an excellent life to counter extreme wear and impact conditions that it undergoes. Hence it is important to improve its mechanical properties. This study aims to find the effect of tempering temperature on microstructure, hardness, and abrasive wear of High Chromium White Cast Iron used in the manufacture of grinding balls. In this study, the balls in high chromium white cast iron with 12 to 17% Cr, of 50mm and 70 mm in diameter were austenitized at 950°C for 45 min and 55 min for the balls of 50 and 70mm then were quenched in forced air. The balls were tempered at 250°C, 400°C, and 600°C for 120 min and 180 min for both diameters 50 and 70mm respectively, and cooled in the furnace. The results showed that tempering practiced at 250°C and 400°C gives an excellent hardness than balls austenitized at 950°C. It is about 60 HRC and it drops to less than 50 HRC for the tempering at 600°C. This tempering causes a significant mass loss (short life) but tempering at 250°C and 400°C decreases this loss by up to 1.6%. The results of XRD showed the presence of the martensite and carbides type M7C3 after tempering at 250°C and a ferritic matrix after tempering at 600°C.

Abstract—In the second decade of the twenty-first century, blockchain is considered one of the most popular computer technologies. Blockchain is a zero-trust network, making it a potent tool for various services provided that people are ready to believe and invest in it. In the Ethereum world, the blockchain runs on smart contracts, self-executing applications that come at the cost of security. As technology is used increasingly, Election is facing new issues of trust and management. Therefore, E-voting systems are increasingly acceptable because they are more accurate, reliable, practical, and secure. This research purpose is to propose a decentralized elections application based on Ethereum; the application was developed using the Truffle development framework. The actions of the software were written into an Ethereum smart contract, which was then deployed on the Ethereum network. A web interface had been used to read the user's vote before it was broadcast to the Ethereum network through the web3.js API. The ganache was utilized as the Ethereum client. Metalmark was used as a wallet on a website, and the remix was used to deploy the smart contract on the main network, the results of implementing the proposed system show that the cost of each transaction is not stable, its increases with the increase the network load, and the throughput ends up at 14 transactions per second.

The free electron laser is considered one of these important and advanced inventions because it provides a laser beam within various wavelengths of the electromagnetic spectrum. In any laser system device, several parameters must be available on which the efficiency and performance of the laser system are dependent. The Pierce parameter is one of the important parameters in measuring the performance quality of the free electron laser. In this paper, the simulation results were obtained using the MATLAB program to show the important effect of the Pierce parameter on the performance of the free electron laser system. The simulation results showed that the values of the Pierce parameter ranged between (0.01 - 0.03) for the laser beam with long wavelengths, while it ranged between (0.001-0.0001) for the short wavelengths. The results showed an increase in the efficiency values of the free electron laser system with increasing the values of the Pierce parameter, which represents the ratio between the saturation power and the power of the electron; therefore, it can be used as a specific threshold to measure the efficiency of the laser system. Additionally, the simulation of the Pierce parameter has a direct relation to the small signal gain per unit length.

In this paper, we apply a mathematical model based on cooperative game theory to model cooperation among producers in waste management. Then, we use the Shapely value as a solution concept in a cooperative game to evaluate the cooperation existing among producers, in order to show the potential cost to the waste producers in the case of cooperation and reduce the overall costs of processing non-recyclable waste during the cooperation. Thus, this study concludes that all producers divide sanitary landfills or incineration of non-recyclable waste, meaning that for each producer who earns more, there will be a greater contribution to the disposal or treatment of non-recyclable waste.

In this study, attention was directed to the preparation of nano-copper oxide films and their multiple applications, where a group of recent researchers was presented and compared to reach the optimal phase, then the optimal application, and finally the optimal values in the optimal application. Where metal-oxides are significant technology used in device fabrication in electronic and chemical industries, due to their applications in advanced technologies, which have been attached to the synthesis of copper oxide nanoparticles. These materials present different properties depending on molecular structure. Copper oxide is used in a wide range of applications. The copper oxide phases CuxO are interesting materials, because of their electrical, optical, and thermal properties. Nano-structuring technologies can enhance the performance of this material and produce it with unique properties that don’t exist in its bulk form. Copper oxide could be found in three different distinct phases, this includes CuO, Cu2O, and Cu4O3, which can be prepared by various synthesis techniques, depending on chemical and physical roots. The most two common Cupric oxide phase is the CuO formula, an inorganic material with black color, it represents one of the other two oxides of copper, the second being Cu2O or cuprous oxide with brownish semiconducting properties. Using A technique to prepare the same material with different phases required physical engineering, where the effect of different parameters plays a role. In this article, the chemical and physical properties of particles using hydrothermal technology for the synthesis of copper oxide were briefly reviewed.