An explicit derivation of dispersion relations and spectra for periodic Schrödinger operators on carbon nano-structures (including graphene and all types of single-wall nano-tubes) is provided.

a mild and green method has been developed for the preparation of coumarins derivatives through the one-pot reactions. in our study,various phenols and ethyl acetoacetate compound in which we used silica-supported boron sulfonic acid [sio2/b(so4h)3] as a new, highly efficient and tri-functional inorganic brønsted acid catalyst were processed under solvent-free condition and thermal. the catalys...

In recent years, using Sol-gel procedure for the purpose of laboratory and industrial synthesis of Nano-structures, and especially silica Nano-particles, has been significantly increased. In this research, silica particles were synthesized by Sol-gel procedure and their physical and chemical properties were studied by means of scanning electron microscopy (SEM), transmission electron microscopy...

A series of novel composite phase change materials (PCMs) were tailored by blending PEG and five kinds of diatomite via a vacuum impregnation method. To enlarge its pore size and specific surface area, different modification approaches including calcination, acid treatment, alkali leaching and nano-silica decoration on the microstructure of diatomite were outlined. Among them, 8 min of 5 wt% Na...

Corrosion of steel is one of the most important potential dangers and threats in concrete structures. Corrosion of steel embedded in reinforced concrete plays a key role in reducing the strength and durability of reinforced concrete. Several studies have proposed that alternative approaches to enhancing the performance of reinforced concrete and its resistance to corrosion. In this study, the r...

ABSTRACT The functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acid were afforded sulfonic acid-functionalized magnetic Fe3O4 nanoparticles (Fe3O4@SiO2-SO3H) that can be applied as an organic-inorganic hybrid heterogeneous catalyst. The used Fe3O4 magnetic nanoparticles are 18-30 nm sized that was rapidly functionalized and can be used as catalyst...

Silica boron sulfonic acid [SiO2–B(OSO3H)3] as an inexpensive, reusable, and Lewis and Brønsted acid catalyst was successfully synthesized, and used for the one-pot three-components synthesis of biologically active substituted Hantzsch 1,4-dihydropyridine derivatives  in the absence of solvent at 90ºC. Silica boron sulfonic acid is attractive and efficient, because it plays in two role as a Lew...

Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly contr...

Ultrasound micro-molding technology has proved useful in processing biodegradable polymers with minimum material loss. This makes this technology particularly suitable for the production of biomedical microdevices. The use of silica (SiO2) nanoparticles is also interesting because of advantages like low cost and enhancement of final properties. Evaluation of the capacity to create a homogeneous...