A laboratory-based X-ray reflectometer has been developed to measure the performance of hard X-ray multilayer coatings at their operational X-ray energies and incidence angles. The instrument uses a sealed-tube X-ray source with a tungsten anode that can operate up to 160 kV to provide usable radiation in the 15-150 keV energy band. Two sets of adjustable tungsten carbide slit assemblies, space...

OBJECTIVE To assess enamel surface under scanning electron microscopy (SEM) after resin removal and enamel polishing procedures following brackets debonding, as well as compare the time required for these procedures. METHODS A total of 180 deciduous bovine incisors were used. The enamel surface of each tooth was prepared and brackets were bonded with light cured Transbond XT composite resin. ...

Abstract. In order to study the effect of carbon impurity in plasma on tungsten first wall, hydrogen-carbon mixed ion beam was irradiated to tungsten. It was found that very small amount of carbon (~0.3% or more) significantly enhanced blister formation. According to XPS analysis, all of tungsten atoms in a top surface were combined with carbon atoms to form tungsten carbide (WC) layer (~6 nm t...

  Objective: Increased enamel surface roughness following orthodontic bracket debonding leads to increased plaque accumulation and enamel decalcification. Therefore, different methods are employed to achieve smoother enamel surfaces after bracket debonding. This study compared enamel surface roughness following orthodontic bracket debonding and composite resin removal using white stone and tung...

BACKGROUND Termination of fixed orthodontic treatment is associated with bracket debonding and residual adhesive removal. These procedures increase enamel roughness to a degree that should depend on the tool used. Enamel roughening may be associated with bacterial retention and staining. However, a very limited data exists on the alteration of 3D enamel roughness resulting from the use of diffe...

Accessible online at: www.karger.com/journals/res Hard metal is essentially produced by heating tungsten carbide together with cobalt powder at about 1,500°C. The resultant product consists of about 80% tungsten carbide, 10–20% cobalt, and may also contain minor amounts of other metals, frequently titanium. The combination of tungsten carbide with cobalt may – obviously in a synergistic way [1]...

In this paper, the electric-discharge machining (EDM) of non-contact seal grooves was studied. Two types of material, namely: tungsten carbide and silicon carbide were tested by EDM due to their hard machining behaviors. The geometry of seal grooves is another reason why grinding or other precision machining processes cannot be applied. Four parameters of EDM processes were studied, namely: ele...

Aim: The study evaluated the efficiency of various finishing and polishing systems and the effect of finishing and polishing time by using various procedures on surface roughness and hardness of silorane based (FiltekP90) and methacrylate based (Z100) restorative materials. Method: The surface roughness and surface hardness were measured using a profilometer and Vickers hardness tester respecti...

OBJECTIVE This study aimed to evaluate enamel roughness after adhesive removal using different burs and an Er:YAG laser. MATERIALS AND METHODS The buccal surfaces of forty human premolars were sealed by two layers of nail varnish, except for a circular area of 3 mm in diameter on the middle third. The enamel surfaces were initially subjected to profilometry analysis and four parameters of sur...

Tungsten carbide nanoparticles were supported on a new 3D mesoporous carbon replicated from commercial silica and exhibited selectivity as high as 72.9% for the catalytic conversion of cellulose into ethylene glycol.