Influences of Co-60 gamma-ray irradiation on electrical characteristics of Al2O3 MOS capacitors

Effects of gamma-ray irradiation on the electrical characteristics of Al₂O₃ MOS capacitors such as barrier height, acceptor concentration, series resistance and interface state parameters have been studied by analyzing capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The fabricated MOS capacitors were irradiated with gamma-rays at doses up to five grays. C–V and G/ω–V measurements were recorded prior to and after irradiation at high frequency. The results show that the measured capacitance and conductance values decreased with increasing in irradiation dose and C–V and G/ω curves has been shifted toward the negative voltages. Moreover, the series resistance (R _s) and density of interface states increased with increasing in irradiation dose and density of interface states (D _it) were calculated as order of 10¹² eV^?1cm^?2 prior to and after irradiation. Due to presence and variations in the R _s values, the corrected and the measured C–V and G/ω–V exhibited different behaviors. Therefore other electrical characteristics were assessed from corrected C _c characteristics. It was observed that acceptor concentration decreased with increasing in barrier height of device due to changes in interface states and diffusion potential.     

Energy absorption behavior of stiffness optimized graded lattice structures fabricated by material extrusion

The objective of this study is to investigate the energy absorption performance of the graded lattice energy absorbers designed by a stiffness-based size optimization process under static loadings applied during the in-service conditions. The energy absorber geometry is modeled using three different lattice types, namely complex cubic, octet cubic, face- and body-centered cubic. The stiffness-based size optimization subjected to a static bending load is conducted to determine the optimal strut diameters which produced graded lattice structure designs. To investigate the energy absorption behavior of these graded lattice designs, the nonlinear dynamic explicit finite element analysis (FEA) is conducted under quasi-static compression for each design. The lattice designs are fabricated by a material extrusion technique using the polylactic acid material and the quasi-static uniaxial compression tests are conducted on the fabricated designs. The FEA results are found to be in good agreement with the experimental results. When compared with uniform counterparts, the presented graded lattices exhibit the improved energy absorption in response to uniaxial compression although their designs were derived from a stiffness-based size optimization with bending load.

     

Ionic Liquid Modified Single‐use Electrode Developed for Voltammetric Detection of miRNA‐34a and its Application to Real Samples

The ionic liquid (IL) modified chemically activated (CA) pencil graphite electrodes (PGEs) were developed for label‐free voltammetric detection of miRNA‐34a, and implemented to the real samples. Firstly, the electrochemical characterization of unmodified PGE, CA‐PGE, IL‐PGE and IL‐CA‐PGE was performed by cyclic voltammetry (CV) as well as their DNA binding capacity was studied by electrochemical impedance spectroscopy (EIS) technique. The microscopic characterization of the surface of each electrodes was investigated by scanning electron microscopy (SEM). Differential pulse voltammetry (DPV) technique was used for measuring the oxidation signal of guanine in order to perform a label‐free voltammetric monitoring of a full‐match hybridization specific to miRNA‐34a. The selectivity of biosensor was tested against to miRNA‐155, miRNA‐660 as well as to the mismatch sequence of miRNA‐34a. The further selectivity of this proposed biosensor was studied in the mixture of samples containing miRNA‐34a with other miRNAs (1 : 1). The voltammetric detection of miRNA‐34a was also explored in the artificial serum medium as fetal bovine serum (FBS) and also in total RNA samples isolated from HUH‐7 human hepatocellular carcinoma cell line.     

Investigation of Luminescence Properties of Eu3+, Dy3+ and Gd3+ Doped MgAl2Si2O8 Red‐emitting Phosphors

Rare‐earth‐doped aluminosilicates of alkaline earth MgAl₂Si₂O₈: Eu³⁺, Dy³⁺ and MgAl₂Si₂O₈: Eu³⁺, Gd³⁺ were synthesized by the solid state reaction method at 1300 ^oC. The phosphors were characterized by X‐ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). X‐ray powder diffraction studies show that the phosphors were crystallized in the triclinic crystal system. The phosphors show characteristic broad band phosphorescence of Eu³⁺. This broad band phosphorescence has red emission bands in the range of 580–705 nm corresponding to ⁵D₀ → ⁷F_j (j:0,2,3,4) transitions of Eu³⁺.     

Synthesis and characterization of folic acid-chitosan nanoparticles loaded with thymoquinone to target ovarian cancer cells

The aim of the present research was to formulate and characterize radioiodinated folic acid-chitosan conjugated thymoquinone nanoparticles (FATQCSNPs) and to increase targeting ability on ovarian cancer cell. The dose of drug-loading into the FATQCSNPs and the amount of folic acid on the FATQCSNPs surface were determined as a 20.0?±?1% and 46.0?±?0.5%, respectively. Cell viabilities (%) determined on SKOV-3 and Caco-2 cells for 48 h. TQ, TQCS and FATQCS were very cytotoxic with lower IC₅₀ values on both cell lines. At specific-activity-dependent incorporation study, the incorporation efficiencies of ¹³¹I-FATQCSNPs was higher than that of ¹³¹I-TQ on SKOV3 cell lines.

     

Sol-gel thin films with anti-reflective and self-cleaning properties

Self-cleaning photocatalytic TiO₂ films are beneficial since they reduce the maintenance cost and enhance the efficiency of various optical systems, especially thermal and photovoltaic solar systems. However, the presence of a TiO₂ layer on glass reduces the transmission of incident light, which leads to a decrease in efficiency. This drawback can be overcome by applying a layer of anti-reflective coating beneath the TiO₂ layer. Generally, the anti-reflective layer is porous silica. The presence of the anti-reflective layer compensates for the loss of light transmittance caused by the photocatalytic TiO₂ top layer. This paper reviews some of the previous and the latest fundamental studies in the literature on anti-reflective, self-cleaning and multi-functional films.     

Steady energy deposition at Mach 5 for drag reduction

Experiments addressing the effect of energy deposition via arc discharge on $15^\circ $ half angle-truncated cone-cylinder configurations at Mach 5 flow were carried out. The arc discharge was accomplished using a setup that consisted of a power supply, a high voltage unit and tungsten electrodes. Discharge-on tests were compared to discharge-off tests to evaluate the net effect of the energy deposition. Flow visualisation revealed the presence of a heated wake downstream of the energy spot. Compression waves were observed on top of the wake of the heated channel, which were oscillatory in nature. The deposited energy of 7 W shows a repeatable influence on the measured drag force for all the models at close arc-to-nose distances.     

Semi-analytical study of free vibration characteristics of shear deformable filament wound anisotropic shells of revolution

Free vibration characteristics of filament wound anisotropic shells of revolution are investigated by using multisegment numerical integration technique in combination with a modified frequency trial method. The applicability of multisegment numerical integration technique is extended to the solution of free vibration problem of anisotropic composite shells of revolution through the use of finite exponential Fourier transform of the fundamental shell equations. The governing shell equations comprise the full anisotropic form of the constitutive relations, including first-order transverse shear deformation, and all components of translatory and rotary inertia. The variation of the stiffness coefficients along the axis of the shell is also incorporated into the solution method. Filaments are assumed to be placed along the geodesic fiber path on the shell of revolution resulting in the variation of the stiffness coefficients along the axis of the composite shell of revolution with general meridional curvature. Sample solutions have been performed on the effect of the variation of the stiffness coefficients on the free vibration behavior of filament wound truncated conical and spherical shells of revolution.