Рентгеновский детектор на основе CdZnTe в режиме поперечной и продольной фотопроводимости

The work considers "transverse" and "longitudinal" photoconductivity modes, regarding the direction of radiation, photoconductivity in semiconductor detectors of CdZnTe. Mathematical calculations were made from the representation of the internal area of the detector in the form of radiation absorption sites. The results of the calculations are compared with experimentally measured photocurrent of the detector with a cross section of 2x2 mm CdZnTe from the direction of its radiation by X-ray. From the ratio of photocurrents in the range of X-ray radiation energies 35-72 keV for these two cases, a linear coefficient of X-ray absorption by the CdZnTe detector is determined.

Growth of ultra-dense MoS2 nanosheets on carbon fibers to improve the mechanical and tribological properties of polyimide composites

To enhance the interface bonding of polyimide (PI)/carbon fiber (CF) composites, CFs were functionalized by introducing a polydopamine (PDA) transition layer, whose active groups provide absorption sites for the growth of molybdenum disulfide (MoS2) nanosheets and improve the bonding strength with PI. Uniform and dense MoS2 nanosheets with thicknesses of 30–40 nm on the surface of the PDA@CF were obtained via a subsequent hydrothermal method. As a result, the interface between the CF and the PI matrix becomes more compact with the help of the PDA transition layer and MoS2 nanosheets. This is beneficial in forming PI/CF-MoS2 composites with better thermal stability, higher tensile strength, and enhanced tribological properties. The lubricating and reinforcing effects of the hybrid CF-MoS2 in the PI composite are discussed in detail. The tensile strength of the PI/CF-MoS2 composite increases by 43%, and the friction coefficient and the wear rate reduce by 57% and 77%, respectively, compared to those of the pure PI. These values are higher than those of the PI/CF composites without MoS2 nanosheets. These results indicate that the CF-MoS2 hybrid material can be used as an additive to improve the mechanical and tribological properties of polymers.

Corrosion Protection of Mild Steel by a New Phosphonated Pyridines Inhibitor System in HCl Solution

The adsorption behavior and inhibition mechanism of (1, 4, 7-Tris [hydrogen (6-methylpyridin-2-yl) phosphonate] -1, 4, 7-triazacyclononane) (TPP) on the corrosion of mild steel in 1 M HCl were investigated by weight loss technique, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods for different concentrations at 25°C. The results show that the inhibition efficiency values depend on the amount of immersion times and the concentration. A 90% efficiency is found at the highest concentration of the studied compound according to weight loss measurements. The adsorption of the investigated inhibitor on the mild steel surface was well supported using an AFM study. For the assignment of the absorption sites, we performed quantum chemical calculations with (DFT) method. The interaction between the inhibitor and iron surface were performed by molecular dynamic (MD) simulations. In this paper, experimental methods and results used to assess the efficiency of the studied compound are presented.

The Effect of UV Illumination on the Room Temperature Detection of Vaporized Ammonium Nitrate by a ZnO Coated Nanospring-Based Sensor

The effect of UV illumination on the room temperature electrical detection of ammonium nitrate vapor was examined. The sensor consists of a self-assembled ensemble of silica nanosprings coated with zinc oxide. UV illumination mitigates the baseline drift of the resistance relative to operation under dark conditions. It also lowers the baseline resistance of the sensor by 25% compared to dark conditions. At high ammonium nitrate concentrations (120 ppm), the recovery time after exposure is virtually identical with or without UV illumination. At low ammonium nitrate concentrations (20 ppm), UV illumination assists with refreshing of the sensor by stimulating analyte desorption, thereby enabling the sensor to return to its baseline resistance. Under dark conditions and low ammonium nitrate concentrations, residual analyte builds up with each exposure, which inhibits the sensor from returning to its original baseline resistance and subsequently impedes sensing due to permanent occupation of absorption sites.

Computational Prediction of Trimethylgallium Adsorption on Si(100)(2×1) in Atomic Layer Deposition

The computational prediction of the surface adsorption in atomic layer deposition of gallium oxide by using trimethylgallium (TMG) is investigated. One dimer of Si (100)(2×1) is used as the substrate. The hydroxyl radicals are used to produce the absorption sites for the TMG adsorbed surface as OH–Si–Si–OH surface species. Two sites adsorption of the TMG on the surface are predicted. The geometry, vibrational frequency, and free energy of –OH adsorption sites and TMG adsorption are calculated by Gaussian 09 package by using standard B3LYP method. The results showed that TMG is possible to adsorb on silicon dimer with two sites adsorption. The geometry and vibrational frequencies are also reported in this paper.

Separation of light confinement and absorption sites for enhancing solar water splitting

More than 30% enhancement in photocurrent is achieved by separating light confinement and absorption sites within the solar cell.