introduction: the aim of this study was to evaluate the morphological changes and quantitatively assess the roughness of dentin after the ablation with a ytterbium-doped potassium yttrium tungstate (yb: kyw) thin-disk femtosecond pulsed laser of different fluences, scanning speeds and scanning distances. method: twelve extracted human premolars were sectioned into crowns and roots along the cem...

Pulsed laser driven modifications of one Cl monolayer (ML) chemisorbed on Si(100) are studied by time of flight mass spectrometry (TOF) of the desorbed molecules, Auger electron spectroscopy @ES) of the modified surface, and Cl depth profile analysis by secondary ion mass spectrometry (SIMS). The experimental conditions are that of surface melting. Evidence of Cl diffusion to the bulk during su...

A hydrodynamic model based on transport equations and semi-empirical multiphase equations-of-state for metals is developed and applied to simulation of short pulse laser melting and resolidification. New computational algorithms are developed for modeling of two-phase zones of solid-liquid and liquid-gas coexistence, as well as for explicit tracking of interfaces between the phases. The model a...

The aim of this work was to synthesize TiC reinforced coating on carbon steel via reduction of ilmenite powder. A mixture of ilmenite and graphite was pre-placed on AISI 1020 steel surface. The effect of the addition of excess graphite amounts on the progress of synthesis of carbide particles was studied. The evolution of phases in different coatings was analysed via X-ray diffraction and scann...

PURPOSE The present study was performed to evaluate the effect of erbium:yttrium-aluminium-garnet (Er:YAG) laser irradiation on the change of hydroxyapatite (HA)-coated implant surface microstructure according to the laser energy and the application time. METHODS The implant surface was irradiated by Er:YAG laser under combination condition using the laser energy of 100 mJ/pulse, 140 mJ/pulse...

This study applied laser surface melting process using CW(Continuous wave) Yb:YAG laser and cold-work die steel SM45C and investigated microstructure and hardness. Laser beam speed, power and beam interval are fixed at 70 mm/sec, 2.8 kW and 800 μm respectively. Depth of Hardening layer(Melting zone) was a minimum of 0.8 mm and a maximum of 1.0 mm that exceeds the limit of minimum depth 0.5 mm a...

The mechanisms of short pulse laser interactions with a metal target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron-phonon equilibration, and electron heat conduction. Three regimes of material response to laser irradiation are identified in simulations performed with a 1 ps laser pulse, w...

INTRODUCTION The aim of this study was to evaluate the effect of dental surface treatment with Erbium-Doped Yttrium Aluminum Garnet(Er: YAG), Neodymium-Doped Yttrium Aluminium Garnet(Nd: YAG) and Carbon Dioxide Laser (CO2) lasers and sodium ascorbate to recently home bleached enamel by scanning electron microscope (SEM). METHODS Thirty extracted human third molars were selected for this in vi...

introduction: the main purpose of the present study was to describe the ultra structural changes which happened after treatment of the root surfaces with ultrasonic and hand devices followed by erbium-doped yttrium aluminum garnet (er:yag) laser irradiation. methods: sixty single-rooted maxillary and mandibular teeth which had been extracted due to periodontal problems were collected. crown and...

The generation of crystal defects in a Cr target irradiated by a short, 200 fs, laser pulse is investigated in computer simulations performed with a computational model that combines the classical molecular dynamics method with a continuum description of the laser excitation of conduction band electrons, electron-phonon coupling, and electron heat conduction. Interatomic interactions are descri...