Journal of Engineering Sciences / Журнал інженерних наук
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Item Comparative analysis of dielectric properties of polyvinyl alcohol and polyethylene(Sumy State University, 2024) Javanbakht, T.The article presents a new comparative analysis of the dielectric properties of polyvinyl alcohol (PVA) and polyethylene (PE) at different temperatures and their other physical properties. The characteristic peaks were observed in the FTIR spectra of the polymers. The amounts of carbon and oxygen on PVA’s surface differed from PE. It was hypothesized that these properties could be affected by the increase in temperature and difference in the chemical structures of the polymers. We investigated the dielectric properties of these polymers between 20 °C and 100 °C. Our results revealed that the dielectric properties of these polymers were not the same. The actual permittivity values of PVA at low temperatures were almost constant for all frequency values and increased at higher temperatures with the decrease in frequency. The same pattern concerning the increase of imaginary permittivity of this polymer was observed at low frequencies. The increase of the real and imaginary permittivity of the PVA accompanied the increase in temperature. The actual permittivity of PE was almost constant with the frequency at different temperatures. However, the imaginary permittivity of this polymer showed an increase at low frequencies. The increase in temperature accompanies the increase of the PE’s imaginary permittivity. As expected, the capacitance, like permittivity, changed differently for the polymers. Moreover, an increase in temperature had more effect on the conductivity of PVA than that of PE. The difference in these polymers’ dielectric properties could be due to their chemical structures. The results of this article can be used for further applications of PVA and PE in science and engineering.Item Optimization of Cdx transcription factors characteristics(Sumy State University, 2023) Javanbakht, T.This study presents a new application of TOPSIS for the optimization of transcription factors characteristics. This application is essential as it can help compare the characteristics of these proteins and determine the optimized output of their comparison with this decision-making method. The hypothesis in this article was that according to the previous study of the Cdx transcription factors, as the Cdx2 transcription factor showed more robust characteristics than Cdx1 and Cdx4, the TOPSIS method would show a better rank position of these first proteins in comparison with the two other ones. Moreover, the engrailed repressor domain EnRCdx1 used in the plasmid showed the reduction of the pax3 gene expression in comparison with the induced regulation of the gene expression with the production of the Cdx1, Cdx2, and Cdx4 transcription factors using the corresponding plasmids, the worst rank position with TOPSIS was expected for this repressor domain. The results obtained with this ranking method showed that the rank positions of the transcription factors and the repressor domain corresponded to their compared properties. Moreover, the change in the weight values of the candidates showed the modification of their distances from the best and worst alternatives and closeness coefficients. However, as expected, the candidates’ rank positions were unchanged, and the Cdx2 transcription factor was still the best candidate. The results of this article can be used in computer engineering to improve biological applications of these proteins.Item Rheological properties of superparamagnetic iron oxide nanoparticles(Sumy State University, 2021) Javanbakht, T.; Laurent, S.; Stanicki, D.; Salzmann, I.The present study focuses on the rheological properties of polyethylene glycol (PEG) modified, positively charged, and negatively charged superparamagnetic iron oxide nanoparticles (SPIONs) at different temperatures. We hypothesized that the surface properties of these nanoparticles in the water did not affect their rheological properties. These nanoparticles had not the same surface properties as SPIONs-PEG had not to charge on their surface whereas positively charged and negatively charged ones with amine and carboxyl groups as their surfaces had positive and negative surface charges, respectively. However, their rheological behaviors were not different from each other. The comparative rheological study of SPIONs revealed their pseudo-Newtonian behavior. The viscosity of SPIONs decreased with the increase in temperature. At low shear rates, the shear stress of SPIONs was independent of rate and increased with the increase of rate. Moreover, at high shear rates, the shear stress for PEG-SPIONs was more than those for positively charged and negatively charged SPIONs. These measurements also revealed that at high shear rates, the shear stress of samples decreased with the increase of temperature. The shear stress of samples decreased with the increase of shear strain and the temperature. We also observed that all the samples had the same amount of shear strain at each shear stress, which indicated the exact resistance of SPIONs to deformation. Furthermore, the shear modulus decreased with time for these nanoparticles. These results suggest that these nanoparticles are promising candidates with appropriate properties for fluid processing applications and drug vectors in biomedical applications.