Density Functional Theory; A New Route for Structural and Thermodynamic Parameters Calculations

Structural and thermodynamic parameters of the studied virgin polymeric matrices poly e-caprolactone (PCL), Chitosan (Chi) and their polymer blend were investigated using theoretical density functional theory (DFT). Thermodynamic functions were calculated based on vibrational frequencies and optimized geometrical coordinates in the temperature range 25-1000 °K which cannot be amended easily. Calculated free energy was found to be convex in terms of extensive variable and concave in terms of intensive ones

Synthesis and optimization of Novel Chitosan/Cellulose Acetate Natural Polymer Membrane for water treatment

Chitosan (Ch) and Cellulose Acetate (CA) natural polymer in addition to other samples with different mass fractions of Chitosan/Cellulose Acetate (Ch/CA) were synthesized via simple casting route. Prepared samples were studied using FT-IR and UV/vis spectroscopic techniques. Structural variations due to the process of blending were retraced using X-ray diffraction data (XRD) and morphological investigation using scanning electron microscopy (SEM). Obtained spectral data reveals compatibility and complexation between polymer constituents identified through presence of polymer characteristic peaks with small variation in both intensity and position along with change in the value of optical energy gap from UV optical absorption spectral data. XRD pattern indicate the semicrystalline nature of the studied sample with an observable change in the crystallinity. Moreover, scanning electron microscopic (SEM) micrographs reveals homogenous structure without any evidence for agglomerations nearly in all compositions

A comprehensive study on optical features, gamma photon buildup factors and neutron shielding capability of B2O3-SB2O3-LI2O-BI2O3 glasses

ABSTRACT. Linear, nonlinear optical properties, photon buildup factors, and neutron shielding capability of glasses with chemical composition (65-x)B2O3-10Sb2O3-25Li2O-xBi2O3, where x = 0 (BSLB0) – 20 (BSLB20) mol% with steps of 4 mol% were examined. Molar refractivity (Rmolar) and molar polarizability (αmolar) were increased as Bi2O3 content mol% increase in the examined BSLB-glasses. The values of metallization criterion (Mcriterion) confirmed that the BSLB-glasses were non-metallic materials. The static (εstatic) and optical (εoptical) dielectric constants having the same trend of the refractive index (noptical). Values of optical electronegativity (χ*) were reduced from 0.825 for BSLB0 (Bi2O3 = 0 mol%) glasses to 0.758 for BSLB20 (Bi2O3 = 20 mol%) glasses. The linear electric/dielectric susceptibility (χ(1)) increased from 0.370 to 0.397. The nonlinear optical susceptibility (χ3) and nonlinear refractive index n2optical were enhanced by increasing Bi2O3 content in the BSLB-glasses. The BSLB20 glasses presented the least exposure and energy absorption build-up factors (EBF and EABF) at all considered thickness. BSLB20 sample achieved the best fast neutron removal cross section ( ) shield among all glasses. The total stopping powers (TSP) follows the trend (TSP)BSLB0 < (TSP)BSLB4 < (TSP)BSLB8 < (TSP)BSLB12 < (TSP)BSLB16 < (TSP)BSLB20. The electron absorbing and hence shielding capacity of the BSLB-glasses improves as their Bi2O3 content increase.     KEY WORDS: Antimony lithium-borate glasses, Optical properties, Buildup factors, Neutron shielding   Bull. Chem. Soc. Ethiop. 2022, 36(4), 949-962.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i4.19                                                     &nbsp

The effect of Li2O and LiF on structural properties of cobalt doped borate glasses

AbstractTwo glassy (LiF–B2O3) and (Li2O–B2O3) systems containing different content of CoO dopants (0.05, 0.1, 0.15, 0.2wt%) were prepared. UV/Vis optical absorption of base glasses reveals a strong UV absorption bands attributed to unavoidable contaminated trace iron impurities. CoO-doped glasses show extra three visible bands due to both octahedral and tetrahedral Co2+ ions related to the little variation between energies of ligand field stabilization between the two coordination states. Fluoride containing glasses show limited variations in the spectral properties due to the different ligand strength of the anions (F− and O2−). FTIR spectra display characteristic modes of vibrations due to triangular and tetrahedral borate groups. It is assumed that LiF acts as Li2O in promoting the formation of tetrahedral (BO3F) units which possess the same wavenumber position for vibrations of (BO4) units in the range of 800–1200cm−1. CoO causes no distinct variations in number or position of characteristic IR vibrational bands due to their low dopant level (0.05–0.2%). A new suggested trial has been utilized to calculate the percent of four coordinated borons from both optical and FTIR spectra to give more insight on the role of CoO as dopant on these spectral properties and on the calculated parameters

Morphological, Thermal and Electrical Properties of (PEO/PVP)/ Au Nanocomposite Before and After Gamma-Irradiation

Gold nanoparticles (Au NPs) have been successfully biosynthesized by Chenopodium murale (C. murale) leaf extract. Au NPs were incorporated within polyethylene oxide (PEO)/polyvinyl pyrrolidone (PVP) polymer blend by casting method. Scanning electron microscope (SEM), Differential scanning calorimetry (DSC), and DC electrical resistivity were used to investigate the morphological, thermal, and electrical properties of blend/Au nanocomposite before and after gamma-irradiation at different doses (1, 2, 3, 4 and 5 MR).SEM micrographs confirmed the dispersion of Au NPs within the polymeric matrix due to effect of irradiation process. DSC analysis showed that the thermal stability for irradiated samples was improved as compared with pure blend and its nanocomposite. DC measurements revealed nonlinear behavior for electrical resistivity versus temperature. The electrical resistivity values for blend/Au nanocopmosite and its high irradiated samples were less compared to pure blend

ZnO/CuO nanocomposite-based carboxymethyl cellulose/polyethylene oxide polymer electrolytes for energy storage applications

As a part of this investigation, polymer nanocomposite films were obtained by the casting method whereby polyethylene oxide (PEO) was mixed with carboxymethyl cellulose (CMC) at a 70:30 wt ratio (PEO/CMC) as a base before adding different concentrations (0.0, 0.3, 0.8, 2, 4, and 6 wt%) of ZnO/CuO nanocomposite (ZC NC) as a dopant, prepared by the sol-gel method. Subsequent analyses revealed that, compared with the pure mixture, the dielectric parameters and conductivity of the polymer nanocomposite (CMC/PEO-ZC NC) films markedly improved with the increase of ZC NC up to 2 wt%, while a decrement was noted for 4 and 6 wt%. Thus, the optimal concentration (CMC/PEO-ZC NC 2 wt%) was used in the subsequent investigations focusing on dielectric properties, and the temperature dependence of the dielectric parameters and conductivity. As ZC NC addition yielded beneficial outcomes, the structural and morphological changes caused by the doping process were successfully counteracted, as confirmed by the x-ray diffraction (XRD) and scanning electron microscopy (SEM) results. The calculated relaxation time (τ), activation energy (Ea), and improved dielectric properties suggest that these nanocomposite films are promising candidates for the development of solid-state supercapacitors

Effect of Gamma-irradiation on biosynthesized gold nanoparticles using Chenopodium murale leaf extract

Eco-friendly synthesized gold nanoparticles (Au NPs) were successfully prepared via facile biosynthesis of Chenopodium murale (C. murale) leaf extract. Biosynthesized Au NPs were characterized by Ultraviolet/Visible spectroscopy (UV/vis.), Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction and transmission electron microscopy (TEM) techniques. The study was extended to retrace the effect of different gamma irradiation doses on the size of prepared NPs. UV/vis. spectra showed a single peak at 531 nm attributed to the surface plasmon resonance (SPR) peak of Au NPs. The blue shift of SPR peak after irradiation process indicated that gamma irradiation could be utilized as size control partner. Transmission electron micrographs (TEM) showed a decrease in the size of Au NPs and a narrow size distribution with an increase in the gamma irradiation dose. Results of TEM were coinciding with those obtained from UV/vis. spectra. Bragg reflections in X-ray diffraction analysis and diffraction pattern of TEM confirmed the presence of face-centered cubic (FCC) Au NPs with (111), (200), (220), and (311) reflection planes. Fourier transform infrared (FT-IR) analysis revealed the physical and chemical complexation of gold with extract. Energy dispersive X-ray spectroscopic analysis (EDAX) confirmed the presence and biosynthesis of Au NPs