Determination of Impurities in Gallium Oxide by NAA

Neutron activation analysis has been applied to determine 12 elements, viz. Na, Mn, As, Fe, Co, Zn, Se, Sc, Cr, Sb, Hf and Ta in high-purity Ga₂O₃. The first 7 elements could be determined by anion exchange separation and isopropyl ether extraction, and the last 8 elements by instrumental method. It is recommended that the first 3 elements are determine by one of the radiochemical modes and the others by the instrumental method.     

Effect of hydrogen doping in ZnO thin films by pulsed DC magnetron sputtering

This study examined the role of hydrogen impurities in highly oriented ZnO thin films. Hydrogen intentionally incorporated was found to play an important role as a donor in n-type conduction, improving the free carrier concentration. The increase in the conductivity of ZnO thin films was attributed to the two centers assigned to isolated hydrogen atoms in the anti-bonding sites as well as bond-centered interstitial hydrogen located between the Zn–O bonds and Zn vacancy passivated by one or two hydrogen atoms. Micro Raman spectroscopy showed two additional modes at approximately 501 and 573 cm⁻¹. These two peaks were attributed to damage to the crystal lattice, which could be explained by the optical-phonon branch at the zone boundary and host lattice defects, such as vacancy clusters, respectively.     

Remarks on Quasilinear Hyperbolic Equations with Dynamic Boundary Conditions

In this paper the non-existence of global solutions of two fourth-order hyperbolic equations with dynamic boundary conditions is considered. Here we prove stronger results than that of M. Kirane, S. Kouachi and N. Tatar by a different method.     

Low emissivity Ag/Si/glass thin films deposited by sputtering

Si was deposited on the glass substrate as an interlayer for the 2-D growth of Ag thin films because Si has a strong binding energy against Ag and can lead to a negative surface energy change in Ag/glass. The Si interlayer induced an extremely smooth and flat Ag surface, which effectively reduced the resistance and enhanced the reflectance in the IR region. In particular, Ag (9 nm)/Si (3 nm)/glass showed 0.074 emissivity and ∼91% reflectance in the IR region with 67% transmittance in the visible region.     

Task-related modulation of anterior theta and posterior alpha EEG reflects top-down preparation

Background  

Prestimulus EEG alpha activity in humans has been considered to reflect ongoing top-down preparation for the performance of subsequent tasks. Since theta oscillations may be related to poststimulus top-down processing, we investigated whether prestimulus EEG theta activity also reflects top-down cognitive preparation for a stimulus.