Ohmic contacts to AlGaN/GaN heterostructures, which have low contact resistance and a good surface morphology, are required for the development of high temperature, high power and high frequency electronic devices. The paper presents the investigation of a Ti/Al based Ti/Al/Ni/Au ohmic contact to AlGaN/GaN heterostructures. Multilayer metallization of Ti/Al/Ni/Au was evaporated by an electron g...

The oxidation of Ti terminated NiTi surfaces is investigated with density functional theory. The surfaces considered are (001) and (110) of the austenite phase (B2) and (010) of the martensite phase (B19’). The favored adsorption sites for atomic oxygen are fourfold hollow on B2 (001), and twofold bridged between two surface Ti atoms on B2 (110) and B19’ (010). Adsorption of one oxygen molecule...

statement of problem: various factors are involved in causing inflammation following root canal treatment. controlling these factors may relieve the related pain. one of these factors is extrusion of debris beyond the apex. although debris extrusion happens in all instrumentation techniques, researchers have declared that in coronal flaring technique, there is minimum debris extrusion. purpose:...

AIM The purpose of this study is to achieve an effective method to remove root canal filling material from the root canal system. The study, thus, aims to evaluate the efficacy of the cleaning ability of two different rotary Ni-Ti systems; ProTaper Retreatment files and RaCe System compared to hand instrumentation with Hedstrom files for the removal of gutta-percha during retreatment. MATERIA...

in this research, tribological behavior of ti-ni-p intermetallic coatings on titanium substrates have been investigated under dry reciprocating conditions. hardness profile testing results exhibit that high surface hardness has been attained and static indentation result shows that the intermetallic coating has better adhesion strength than the conventional ceramic coatings. in this respect, th...

The effects of metal combinations on cytotoxicity were examined following dynamic extraction by freely gyrating two spherical metals in a glass vessel. The cell viabilities of an Au alloy, a Ag-Pd-Au alloy and Ti were little affected by combinations among three metals. Cell viability ranged between 60 and 80% when precious alloys were in combination with Co-Cr or Ni-Cr alloys. Ti showed a clear...

Nickel-titanium-oxide (Ni-Ti-O) nanotube arrays (NTAs) prepared on nearly equiatomic NiTi alloy shall have broad application potential such as for energy storage and biomedicine, but their precise structure control is a great challenge because of the high content of alloying element of Ni, a non-valve metal that cannot form a compact electronic insulating passive layer when anodized. In the pre...

use of rotary nickel-titanium (niti) instruments for endodontic preparation has introduced a new era in endodontic practice, but this issue has undergone dramatic modifications in order to achieve improved shaping abilities. cone-beam computed tomography (cbct) has made it possible to accurately evaluate geometrical changes following canal preparation. this study was carried out to compare cana...