Journal of advanced materials and processing
Volume:11 Issue: 1, Winter 2023

In this work, we analyze and compare the optical properties of spherical A: CdSe–ZnS–CdSe and B: ZnS-CdSe-ZnS core–shell– shell quantum dots (CSQDs). Under the framework of the effective mass envelope function theory, the nonlinear susceptibilities associated with inter-sub-band transitions in the conduction band are computed by solving the three-dimensional Schrödinger equation for A and B QDs in the presence of impurity. We theoretically investigate the third-order susceptibilities and optical absorption coefficients as a function of core radius while the outer radius of quantum dots was fixed. The numerical calculations show that QD size plays a fundamental role in determining the nonlinear optical properties of QDs. The susceptibilities and the absorption coefficients have pronounced single peaks (resonance) and depend strongly on the geometry of these two quantum dots as well as the effect of the quantum confinement. Our theoretical study shows that susceptibility and absorption coefficients peaks are red-shifted by increasing the core radius, and the magnitude of susceptibility and absorption coefficient increase. The resonant magnitudes Im (𝜒 (3) ) of A and B-CSQD are negative and are around (-2.4) and (-2.5), respectively. While, for the core radius of R1 = 40 nm, Real (𝜒 (3) ) of A and B-CSQD changes significantly near the resonant frequency from positive value (+1.7, +1.6) to negative one (-1.7, -1.6), respectively. Furthermore, for R1 = 40 nm, the absorption coefficient of A-CSQDs has reached a maximum with the magnitude of situated at approximately 0.02 eV. In contrast, this value is equal to for BCSQD. Our computational results may open a new window in the development of QDs structures for application in optoelectronic devices.

Membrane technology has attracted significant research attention due to its many advantages in gas separation. In the present study, Blended membranes were fabricated utilizing sulfonated poly (ether ether ketone) (SPEEK) and poly (etherimide) (PEI) with varying quantities of multi-wall carbon nanotubes (MWCNTs) (up to 2 wt.%). The membranes produced were analyzed using X-ray diffraction (XRD), scanning field emission electron microscopy (FESEM), and Fourier transformed infrared spectroscopy (FTIR). The impact of the SPEEK/PEI composition on membrane selectivity was examined at various feed pressures ranging from 2 to 8 bar. The selectivity and gas permeability values varied between the individual polymers and showed systematic fluctuations with changes in the SPEEK/PEI content in the blends. The incorporation of MWCNTs into the blend resulted in an enhancement of the CO2/ N2 selectivity. The membrane containing the same amount of SPEEK and PEI, along with 1 wt.% of MWCNTs (designated as SP55M1), exhibited an approximately 22% increase in the selectivity of CO2/N2 compared to the pristine membrane.

Severe plastic deformation (SPD) has become an efficient route for producing ultrafine-grained and nanostructured high-strength metallic materials. The present study investigates the feasibility of synthesizing rod-shaped nanostructured pure aluminium samples with the newly presented severe plastic deformation (SPD) method called cyclic contraction/expansion extrusion (CCEE). Also, the deformation characteristics of this process were studied using both micromechanical-based finite element simulations and experimental methods. Tensile test results showed a noticeable increase in yield and ultimate tensile strength values to 155 MPa and 191 MPa from the initial values of 56 MPa and 112 MPa, respectively, after the second pass of CCEE processing. The microhardness measurements showed a significant increase in hardness values to 61 Hv from the initial value of 27 Hv at the end of the first and second passes of CCEE. Results showed that the proposed technique is an efficient SPD method capable of imposing severe stains in the order of 20 after six repeated cycles. The constitutive micro-mechanical approach was implemented to predict microstructure evolution during CCEE processing. The UFG cylindrical aluminium samples with a mean grain size of 480 nm at the end of the first pass and 360 nm at the end of the second pass of CCEE were processed from the initial grain size of ~55 μm. The XRD-obtained grain sizes were consistent with the FEM-predicted values.

This paper reports the green preparation of silver oxide and nickel oxide nanoparticles. The malva sylvestris extract was used as the green reductant and capping agent. The prepared nanoparticles were characterized using XRD, SEM, FT-IR, and EDX analysis. The XRD analysis discloses that the prepared silver oxide nanoparticles comprise both Ag2O and Ag metal phases. In addition, it was found that the prepared nickel oxide nanoparticles have an amorphous structure. The FT-IR results show the presence of metal-oxide bonds at the wavenumber range 750-600 cm-1. Also, the green synthesis of the metal oxide nanoparticles was confirmed by the existence of the organic functional groups on the surface of the prepared samples. The SEM images show the spherical nanoparticles in the size range below 50 nm for both prepared nanoparticles. These results reveal the superior ability of the malva sylvestris extract to prepare the fine metal oxide nanoparticles. In this research, synthesized Ag2O nanoparticles (Ag2O NPs) and NiO nanoparticles (NiO NPs) were used as modifiers for carbon paste electrode (CPE) and their effect on the electrochemical determination of Quercetin (QCT) was investigated by using differential pulse voltammetry (DPV).

There are many methods to synthesize metal and metal oxide nanoparticles (NPs) using different reducing agents which are hazardous in nature. Although some researchers have used biobased materials for the synthesis of these NPs, further research is needed in this area. To explore the scope of bio-extract for the synthesis of transition metal NPs, the present paper synthesizes metal NPs replacing hazardous traditional reducing agents. This paper reports the synthesis zero-valent iron nanoparticles (ZVINs) by a green method and investigates the antibacterial activity of these nanoparticles through the extract of Thymus carmanicus. Green synthesis of Thymus carmanicu-Zero Valent Iron Nanoparticles (TC-ZVINs) was carried out in an alkaline environment. The TC-ZVINs were characterized by the use of imaging FESEM and spectroscopic (FTIR and XRD) methods. The TC-ZVINs obtained were a mixture of spherical and quasi-spherical shapes with diameters ranging between 40 and 80 nm. These methods demonstrated that some polyphenols are bound to the surfaces of the TC-ZVINs as a capping/stabilizing agent. Furthermore, The TC-ZVINs, TC extract and different percentages of them have the potential to terminate the pathogenicity of gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria. This property is slightly higher in the TC-ZVINs than in T. carmanicus extract. For both types of bacteria, the diameter of the inhibitory zone obtained from TC-ZVINs was about 10.8.