In this study, catalysts for fatty acid methyl esters (FAME or biodiesel) synthesis with K2CO3 as the active component on an alumina/silica support were synthesized using the sol–gel method, which was followed by drying the “dense” wet gels with supercritical carbon dioxide to obtain the aerogels. The prepared catalysts were characterized by XRD analysis, FTIR spectroscopy and N2 physisorption ...

The electric, electronic, mechanical and thermal characteristics of high density electronic devices can be affected by the physico-chemical characteristics of base materials as well as by trace impurities. It is well known that soft errors caused by trace -emitting impurities are one cause of the faulty operation of electronic devices. This phenomenon was initially reported in May[1] in the 197...

An atomic force microscope (AFM) was used to measure the interactions between a flat Teflon AFTM surface and an -alumina or amorphous silica sphere in cyclohexane as a function of distance of separation. Repulsive van der Waals (vdW) forces were predicted for the interactions between Teflon AFTM and -alumina or amorphous silica according to the negative Hamaker constants, which were calculated ...

Many advanced ceramics are formed by colloidal consolidation using techniques such as sedimentation, centrifugation, or pressure filtration. In all these, the minimization of density variations of various colloidally-consolidated cakes has not been examined systematically until recently. Schilling et al.' used y-ray densitometry to study the density variations in a sedimented cake and showed th...

A compact upconversion fiber laser operating around 810 nm is proposed using thulium-doped silica-based fiber with locally modified thulium environment by high alumina codoping. Using a comprehensive numerical model of thulium doped fiber we investigate performance of the proposed laser. Comparison with two other thulium hosts, fluoride glass and standard silica, is presented. Efficient lasing ...

Introduction We employ a combined computational-experimental approach to probe the Lewis acidity of silica-alumina, and extend this study to the effect of Lewis acidity on the activation and activity of a supported methyltrioxorhenium (MTO) metathesis catalyst. Despite the widespread use of amorphous silica-alumina as a catalyst and a catalyst support, the structures of its Lewis acid sites rem...

The interaction of 12 substituted phenol, three aminophenol and four substituted aniline derivatives with the corn protein zein was studied on zein-coated silica and alumina stationary phases by high-performance liquid chromatography using bidistilled water as mobile phase. Solutes were eluted from the zein-coated supports with different retention times indicating that they bind to the protein ...

The effects of sandblasting media and steam cleaning treatment after sandblast were examined on tensile bond strength of porcelain to titanium. The use of the commercially available silica-coated alumina particles for sandblast was significantly effective for increasing bond strength than the conventional alumina. It might be due to the increased surface roughness and existence of remaining sil...

Polyurethane-based micro- and nano-hybrid composites were produced with controlled porosity to be used as obturation materials. In addition to hydroxyapatite (HAp) micro-particles in the composites, two different ceramics particle types were also added: alumina micro-particles and silica nano-particles. Particles of different sizes provide the materials with improved mechanical properties: the ...