Mesoporous alumina catalysts that incorporate nickel (Ni-Alumina) with different Ni/Al molar ratios of 1:2, 1:5 and 1:10 were synthesized by a one-step sol–gel method using lauric acid as a template. The prepared Ni-Alumina catalysts showed a relatively high surface area with a narrow pore size distribution after calcination at 700 ◦C; these effects were independent of the Ni/Al molar ratio. Al...

Four calcined alumina abrasive particles [ultrafine (0.05 ?m), 3 ?m, 9 ?m and 20 ?m] with defined sizes were investigated for their effects on toothbrush abrasion, surface polishing stain removal in vitro . The existence of a critical particle size (CPS) was shown the first time tooth model system present study CPS ~2.3 d10, 4.3 d50 or 7.8 d90 abrasives apparent. values indicate that 10%, 50% 9...

Insights into the cobalt sulfide formation upon sulfidation (10 % H2S/H2) of cobalt-based materials with 4 wt CoO supported on alumina or silica were obtained by Quick-X-ray absorption spectroscopy monitoring analysed multivariate curve regression analysis. A common pathway is evidenced involving defective CoS2 species transformed around 200−250 °C Co9S8 species. Upon cooling down under sulfidi...

conclusions calcined coral/sodium nitrate as a new, efficient, and natural heterogeneous catalyst used in aldol condensation reaction of ketones and aldehydes led to β-hydroxyketones in good to high yields in appropriate condition. materials and methods marine coral (acropora sp.) was washed several times using methanol-ethyl acetate and deionized water and then dried in an oven at 80°c for 48 ...

Nanoporous alumina membranes exhibit high pore densities, well-controlled and uniform pore sizes, as well as straight pores. Owing to these unusual properties, nanoporous alumina membranes are currently being considered for use in implantable sensor membranes and water purification membranes. Atomic layer deposition is a thin-film growth process that may be used to modify the pore size in a nan...

Abstract Geopolymer refers to a large group of nanoporous, nanoparticulate materials that are synthesized by dissolution and polycondensation aluminosilicates in basic solutions can be made from variety starting materials, such as industrial waste ash, volcanic rock, or calcined clay. Geopolymers X‐ray amorphous, corrosion resistant, refractory, at ambient temperature pressure similar cements. ...

Many pioneers from around the world followed this initial experience but long-term results and good methodology were lacking. Recently, a number of reports 4-6 have focused attention again on an alumina-on-alumina combination. More than 30 years after its introduction into clinical practice, this article considers the current information on the alumina-on-alumina combination from both experimen...

A new rapid, very simple and one-step sol-gel strategy for the large-scale preparation of highly porous γ-Al₂O₃ is presented. The resulting mesoporous alumina materials feature high surface areas (400 m² g-1), large pore volumes (0.8 mL g-1) and the γ-Al₂O₃ phase is obtained at low temperature (500 °C). The main advantages and drawbacks of different preparations of mesoporous alumina materials ...

Monolithic ceramics have been fabricated from coated green fibers to create fibrous microstructures. The fibrous monoliths consist of high aspect ratio polycrystalline regions (cells) of a primary phase separated by thin secondphase regions (cell boundaries) designed to improve fracture resistance. The cells are the remnants of the green fiber which consists of ceramic powder and a polymer bind...

Thin alumina films have found applications in electronic circuits and cutting tools and have been recently explored as protective coatings against high temperature oxidation, but these studies have been relatively rare. In this study, amorphous alumina films 3.5 pm thick were produced by reactive sputtering on Co-30Cr-6Al-0.5Y coatings, using a pure aluminum target in Ar + 0 2 atmosphere. Isoth...