The interaction of alkali metals-specifically, lithium-with polycyclic aromatic hydrocarbons (PAHs) was studied using a variety of electronic structure methods. Electron transfer from lithium to a PAH depends on the size and structure of the PAH and the electronic structure method used. In some cases, we observe an artificial transfer when using density functional theory (DFT) due to the self-i...

In the present study, the microstructure of welded zone of Hastelloy X sheets with thickness of 1 mm via pulsed Nd-YAG laser welding were studied. This welding process was done by autogenus and conductive method. Microstructure were observed by metallurgical OM and SEM. Results shown Solidification of the weld metal is dendritic. The dendrites in the central zone of the welding are fine and equ...

BACKGROUND Recasting the base metal alloys is done as a routine procedure in the dental laboratories whenever there is casting failure or to decrease the unit cost of a fixed partial denture. However, this procedure may affect the metal ceramic bond. Furthermore, it is unclear, as to which test closely predicts the bond strength of metal-ceramic interface. The aim was to compare the bond streng...

AIM The aim of this study was to evaluate the effect of recasting base metal alloy on the metal-ceramic bond strength. MATERIALS AND METHODS A total of 60 test samples were prepared from new and recast nickel-chromium alloy and divided into six groups. In group A0, test samples were prepared from 100% new alloy. Groups A1, A2, A3, A4, and A5 were prepared from 50% new alloy and 50% casting re...

PURPOSE To compare the debonding/crack initiation strength (D/CIS) of a low-fusing pressable leucite-based glass ceramic (PC) fused to metal to a feldspathic porcelain (FP) fused to metal. MATERIALS & METHODS As per ISO 9693:1999, 40 rectangular metal specimens (25.0 mm x 0.5 mm x 3.0 mm) were prepared. Twenty of the specimens were cast in a base metal nickel-chromium alloy (BA), and 20 were ...

in the present study, the microstructure and mechanical properties of the dissimilar welding betweenastm a335 low alloy steel and er309l austenitic stainless steel were investigated using the gastungsten arc welding process. the welding of dissimilar materials between astm a335 low alloy steeland er309l austenitic stainless steel was found to have a significant effect on the microstructure when...

the kinetics of catalyst deactivation and coke formation during dehydrogenation of propane over supported pt–based catalysts and, in particular, the effect of alkali metal promoters on catalyst activity and stability were studied. the analysis of propane conversion data showed that there is an optimum level of alkali metal promoter loading for both catalyst activity and stability.a model based ...

for the first time, this research reports the formation of nanoporous layers of metals on the surface of metal substrates by raney method and their conversion to corresponding porous perovskite layers. the noble metals doped perovskites are used as catalytic converter for reducing automotive pollutants. the use of perovskite as a substrate for the noble metals can reduce the need for such metal...