This study is focused on synthesis of nano-colloidal silica via alkaline water glass solution. Sodium ions of water glass were removed by cation exchanging in a resin column to obtain the silicic acid which was titrated to the solution of sodium silicate. Concentration of the colloidal silica and pH value of the solutions were controlled using different concentrations of alkaline sodium silicat...

The effect of two acids (phosphoric and acetic) and their derivatives (hydrogen di(2-ethylhexyl)orthophosphoric, chloroacetic, dichloroacetic, trichloroacetic, and trifluoroacetic acids) on the retention of selected alkaloids on silica gel plates has been investigated. The dependence of the chromatographic behaviour of the alkaloids on mobile phase diluent and on the concentration of the acids ...

Two  simple  protocols  for  the  synthesis  of  1,  2,  4,  5-   tetrasubstitutedimidazoles  using  nano-SPA  as  a  reusable,  eco-   friendly,  inexpensive,  and  efficient  catalyst  are  reported.  Short   reaction  times,  high  yields,  scale-up  and  easy  workup  are  the   advantages of these protocols.

Knoevenagel condensation between barbituric acid and aldehyde was investigated in the presence of sulfonic acid functionalized nanoporous silica (SBA-Pr-SO3H) and resulted in the formation of arylidene and bis-arylidene barbiturates. Excellent yields and short reaction times are related to the high efficiency of SBA-Pr-SO3H that the reactions take place easily in its nano-pores. SBA-Pr-SO3H as ...

PURPOSE The purpose of this in vitro study was to evaluate the effects of four surface treatments and two resin cements on the repair bond strength of a ceramic primer. MATERIALS AND METHODS Eighty-eight pairs of disks (10 and 5 mm in diameter, 3 mm thickness) were prepared from heat-pressed feldspar ceramics (GC Initial IQ). After being stored in mucin-artificial saliva for 2 weeks, the 10-m...

Knoevenagel condensation between barbituric acid and aldehyde was investigated in the presence of sulfonic acid functionalized nanoporous silica (SBA-Pr-SO3H) and resulted in the formation of arylidene and bis-arylidene barbiturates. Excellent yields and short reaction times are related to the high efficiency of SBA-Pr-SO3H that the reactions take place easily in its nano-pores. SBA-Pr-SO3H as ...

New modified acidic catalysts were prepared from the treatment of silica, titania and silica prepared from hydrolyzed tetraethyl orthosilicate (TEOS) with sulfuric and phosphoric acid. The sulfated and phosphated silica synthesized from TEOS were calcined at 450 and 650 ◦C. These catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmissio...

in this study, different contents of nano-silica, 2 wt.%, 4 wt.% and 6 wt.%, have been added to bitumen tomodify the physical, mechanical and rheological properties of warm mix asphalt (wma). wma iscontaining 2 wt.% of sasobit (mixture of long-chain hydrocarbons). various quality control tests have beencarried out to characterize the modified bitumen and wma. the rheological investigations show...

describes the isolation, properties and structure of 1, which is related to dianemycin (2).X) The fermentation of S. hygroscopicus sp. ATCC 53626 and isolation of crude 1-Na as a hexane soluble oil (150g) was carried out as described elsewhere.2) This material was purified by HPLC on a Waters ^Bondapak C18 column using methanol water (90: 10), followed by HPLC on a silica gel column using methy...

introduction: one of the clinical problems in orthodontics is the bonding of brackets tocomposite restorations. the aim of this study was to evaluate the shear bondstrength of brackets bonded to composite restorations using excite. methods:forty brackets were bonded to composite surfaces, which were embedded inacrylic resin. one of the following four protocols was employed for surfacepreparatio...