The ceramic-insulated cathode leads have been subjected to cyclic heating to a maximum temperature in excess of 7000C. Two such tests have been made, the metal-ceramic seal failing on the first lead, while a coppermolybdenum soldered joint failed on the second lead after six cycles. The design of the cathode lead has been changed to eliminAte this joint. Some experiments have been performed wit...

OBJECTIVE The aims of the study are to assess the marginal accuracy of base metal and titanium alloy casting and to evaluate the effect of repeated ceramic firing on the marginal accuracy of base metal and titanium alloy castings. MATERIALS AND METHODS Twenty metal copings were fabricated with each casting material. Specimens were divided into 4 groups of 10 each representing base metal alloy...

BACKGROUND Fixed orthodontic mechanotherapy is associated with friction between the bracket - wire - ligature interfaces during the sliding mechanics. A sound knowledge of the various factors affecting the magnitude of friction is of paramount importance. The present study was done to analyze and compare the frictional forces generated by a new ceramic (Clarity Advanced) bracket with the conven...

A modular synthesis of tetrasubstituted furan carboxylates using a tandem cycloisomerization/oxidative carbonylation sequence of cyclopropenes has been successfully developed. The Tandem Metal Relay Catalysis (TMRC) pathway accounted for the high efficiency of this transformation.

It is known that the light scattering from the metal particles deposited on the surfaces of cells can be used for increasing light trapping in the solar cells. In this work, plasmonic structures are composite materials that consisted of silver nanoparticles embedded in dielectric films of TiO x -used as cell antireflection coating. The films are deposited by sol-gel method using spin-on techniq...

To include electron-electron correlation effects in the nanosystem we are proposing a combined density-functional-theorydynamical-mean-field-theory (DFT + DMFT) approach, which we have recently shown to be suitable for including correlation effects in small (2-5 atoms) Fe and FePt clusters [1]. This method has several advantages as compared to the widely used DFT + U approach, the most importan...

Zinc-based adsorbents currently in use for H2S removal from tail gas in the oil and gas industry have limited regenerability and reduced performance over multiple cycles [1,2]. Spatially well-distributed metal nanoparticles in mesoporous substrates can be effective in achieving better performance over multiple adsorption and regeneration cycles [3,4]. One of the critical aspects of understandin...

Realistic molecular models of one and two-centre catalytic active sites originating from the cleavage of a precursor material known to give rise to an active double metal cyanide catalyst are described. Via periodic density functional calculations the structure of the proposed catalytic sites are shown to be dependent on electrostatic and structural relaxation processes occurring at the surface...

the aim of this study was to compare the shear bond strength (sbs) of resin modified glass ionomer (rmgi) and composite resin for bonding metal and ceramic brackets.eighty-eight human premolars extracted for orthodontic purposes were divided into 4 groups (n=22). in groups 1 and 2, 22 metal and ceramic brackets were bonded using composite resin (transbond xt), respectively. twenty-two metal and...

The paper presents a discussion of the various types of ceramic joining within a conceptual framework based on the fundamentals of wetting, adhesion, and the thermodynamics of interfacial reactions. Examples are given of solid state diffusion bonding of Pt to alumina and brazing of AlN. Most ceramic-metal bonding is conducted at high temperatures, where chemical reaction is to be expected. The ...