Pd-poly(N-vinyl-2-pyrrolidone)/KIT-6 nanocomposite: Preparation,structural study,and catalytic activity

The Pd-poly(N-vinyl-2-pyrrolidone)/KIT-6 nanocomposite was prepared by an in situ polymerization method and used as an efficient heterogeneous catalyst for C–C bond formation through the Heck coupling reaction of aryl iodides, bromides and chlorides with styrene. The physical and chemical properties of the catalyst were characterized by XRD, BET, FT-IR, TGA, UV-Vis and TEM techniques. The reactions were performed in methanol-water as solvent and the products were obtained in high yield and purity after a simple work-up. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Heck coupling reaction.     

Spectrophotometric Study of the Complexation of Some Lanthanide (III) Ions with a Series of 18-Crowns-6 in DMSO Solution Using Murexide as a Metallochromic Indicator

The complexation of La(III), Ce(III), Pr(III) and Er(III) with 18-crown-6(18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DCY18C6) anddibenzopyridino-18-crown-6 (DBPY18C6) has been studied in dimethylsulfoxide(DMSO) by means of a competitive spectrophotometric method using murexide asa metal ion indicator. The formation constants of the 1 : 1 complexeswere found tovary in the order La(III) > Ce(III) > Pr(III) > Er(III). It was foundthat the structure influences the formation and stability of the resultingcomplexes. The effects ofvarious parameters on complexation are discussed. The order of the stabilityconstants of each lanthanide ion with these macrocycles are18C6 > DC18C6 > DB18C6 > DBPY18C6.     

Composition and in vitro antibacterial activity of essential oils from four Satureja species growing in Iran

The composition and in?vitro antibacterial activity of essential oils from four Satureja species (S. bachtiarica, S. khuzistanica, S. mutica and S. rechingeri) growing in Iran were determined. According to the results of GC-FID and GC-MS analysis, all oil samples were principally composed of phenolic constituents (carvacrol and/or thymol) with the percentages ranging from 41.2% (S. bachtiarica) to 77.7% (S. rechingeri). Determining antibacterial activities by the disc diffusion method against two Gram-positive and two Gram-negative bacteria revealed the maximum activity against Bacillus cereus with a range of minimum inhibitory concentration values from 0.25 to 1?mg?mL(-1) and minimum bactericidal concentration values from 0.5 to 1?mg?mL(-1). The oils of S. khuzistanica and S. rechingeri appeared to be more active in general than those of other species. In conclusion, the essential oils of studied Satureja species have the potential to be considered as alternatives for synthetic food preservatives.     

Assessment of nanocomposites based on unsaturated polyester resin/nanoclay under impact loading

The aim of this study is to investigate the performance of nanoclay reinforced unsaturated polyester (UP) resin under impact loads. Nanocomposite specimens containing nanoclay in 0, 1.5, and 3 (wt%) were prepared by melt mixing method. X‐ray diffraction, transmission electron microscopy analysis, scanning electron microscope photographs, and viscosity changes in liquid state resin confirmed exfoliation and intercalation of the nanoclay in the UP resin system used. Tensile modulus showed an increase with increase in nanoclay content. However, the tensile strength and elongation at break exhibited reducing performance with increase in nanoclay content. Izod impact test results indicated better performance for the specimens containing nanoclay reinforcements, with 1.5 (wt%) of nanoclay specimens showing the highest value. High velocity impact tests were carried out using gas gun in velocity range of 20–100 m/sec and harden steel hemispherical tip projectile with diameter of 8.7 mm and weight of 11.54 g. Results for high velocity impact test indicated better performance by the specimens containing nanoclay, with 1.5 (wt%) nanoclay showing the highest attained value. Damage assessments of impact area for all specimens showed spalling type brittle failure with punch out and sever fragmentation pattern. Copyright © 2011 John Wiley & Sons, Ltd.     

Electrocatalytic activity of porous nanostructured Fe/Pt-Fe electrode for methanol electrooxidation in alkaline media

An electrochemical approach to fabricate a nanostructured Fe/Pt-Fe catalyst through electrodepo-sition followed by galvanic replacement is presented. An Fe/Pt-Fe nanostructured electrode was prepared by deposition of Fe-Zn onto a Fe electrode surface, followed by replacement of the Zn by Pt at open-circuit potential in a Pt-containing alkaline solution. Scanning electron microscopy and energy-dispersive X-ray techniques reveal that the Fe/Pt-Fe electrode is porous and contains Pt. The electrocatalytic activity of the Fe/Pt-Fe electrode for oxidation of methanol was examined by cyclic voltammetry and chronoamperometry. The electrooxidation current on the Fe/Pt-Fe catalyst is much higher than that on flat Pt and smooth Fe catalysts. The onset potential and peak potential on the Fe/Pt-Fe catalyst are more negative than those on flat Pt and smooth Fe electrodes for methanol electrooxidation. All results show that this nanostructured Fe/Pt-Fe electrode is very attractive for integrated fuel cell applications in alkaline media.     

Preparation and characterization of a novel DABCO-based ionic liquid supported on Fe3O4@TiO2 nanoparticles and investigation of its catalytic activity in the synthesis of quinazolinones

In this study, quinazolinone derivatives have been synthesized via a suitable and efficient procedure by one-potmulti-component reactions of 3-amino-1,2,4-triazole or 2-aminobenzimidazole, dimedone and aromatic aldehydes in the presence of Fe₃O₄@TiO₂-IL as nanocatalyst under solvent-free condition. The products were prepared in good to excellent yields using Fe₃O₄@TiO₂-IL magnetic nanocatalyst. The Fe₃O₄@TiO₂ magnetic nanoparticles (MNPs) were prepared using beet juice extract and functionalized with IL based on DABCO. Moreover, the core-shell structured magnetic Fe₃O₄@TiO₂-IL has been characterized by different techniques such as ¹H-NMR, FT-IR, VSM, XRD, SEM, TGA, TEM and EDX. To the best of our knowledge, the prepared ionic liquid displayed a good protective and activator agent for magnetic nanocatalyst.     

Multiple functions of microfluidic platforms: Characterization and applications in tissue engineering and diagnosis of cancer

Microfluidic system, or lab-on-a-chip, has grown explosively. This system has been used in research for the first time and then entered in the clinical section. Due to economic reasons, this technique has been used for screening of laboratory and clinical indices. The microfluidic system solves some difficulties accompanied by clinical and biological applications. In this review, the interpretation and analysis of some recent developments in microfluidic systems in biomedical applications with more emphasis on tissue engineering and cancer will be discussed. Moreover, we try to discuss the features and functions of microfluidic systems.     

Overcoming acid–base copolymer neutralization using mesoporous carbon and its catalytic activity in the tandem deacetalization–Knoevenagel condensation reaction

Research on Chemical Intermediates - Acid–base copolymer materials are of considerable interest because of their fundamental implications for acid–base bifunctional catalysis...     

Investigating the effect of nanolayered silicates on blend segmental dynamics and minor component relaxation behavior in poly(ethylene oxide)/poly(methyl methacrylate) miscible blends

Polymer–silicate nanocomposites based on poly (ethylene oxide), PEO, poly(methyl methacrylate), PMMA, and sodium montmorillonite clay were fabricated and characterized to investigate the effect of nanolayered silicates on segmental dynamics of PEO/PMMA blends. X‐ray results indicate the formation of an exfoliated morphology in the nanocomposites. At low silicate contents, an enhancement in segmental dynamics of blend nanocomposites and also PEO, minor component in blend, is observed at temperature region below blend glass transition. This result can be attributed to the improvement of the confinement effect of rigid PMMA matrix on the PEO chains by introducing a low amount of layered silicates. On the other hand, at high silicate contents, an enhancement in segmental dynamics of blend nanocomposites and PEO is observed at temperature region above blend glass transition. This behavior could be interpreted based on the reduction of monomeric friction between two polymer components, which can facilitate segmental motions of blend components in nanocomposite systems. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011