Current Nanoscience - Volume 8, Issue 6, 2012

In this paper, we are reporting a one step hydrothermal approach to the synthesis of graphene nanosheets via reduction of graphene oxide (GO). The obtained graphene nanosheets are characterized using X-ray diffraction (XRD), UV-vis spectroscopy, Transmission electron microscope (TEM), X-ray photoelectron (XPS) and Raman spectroscopic techniques. XRD analysis revealed the regraphitization process occurred in the graphene nanosheets. The UV-vis spectroscopy showed red shift in the absorption band due to the formation of graphene nanosheets. TEM studies revealed the sheet like morphology of the obtained graphene. XPS spectra confirmed the removal of oxygenated functional groups in graphene due to the hydrothermal reduction reaction. Raman spectra confirmed the restoration of sp2 clusters in graphene sheets after the reduction. The average crystallite size of the sp2 clusters in graphene sheets was calculated from the Raman spectra as 11.76 nm.

This article reports an experiment on specific heat measurement of nanofluids using a calorimeter of the comparison type. The measurement is based on a differential thermal analysis technique. The studied TiO2 and Al2O3 nanoparticles are dispersed in base fluids which are pure water and a mixture of ethylene glycol/water (20/80 wt.%). Concentrations between 0 and 8 vol.% and temperatures are between 15 and 65oC. Results show that the measured specific heat of nanofluids is lower than that of the base liquid decreases as the particle concentrations increases. Furthermore, the specific heat of nanofluids was found to increase with increasing temperatures. When compared with predicted values from existing correlations and data reported by other researchers, measurements are compatible with the prediction from the thermal equilibrium model presented by Xuan and Roetzel. Finally, new correlations are proposed for predicting the specific heat of Al2O3 and TiO2 nanofluids

The Ag/polyaniline (Ag/PANI) films have been prepared by a two-step electrochemical method. The PANI film was firstly grown by a potentiodynamic polymerization method in aniline electrolytes, and then Ag nanoparticles were electrodeposited on the PANI film through potentiostatic methods in 0.1 M AgNO3 solution. The products were characterized in detail by multiform techniques: X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDS), scanning electron microscopy (SEM). The obtained Ag/PANI electrode was used as glucose sensor to detect glucose in 0.1 mol/L KOH. The results show excellent electrocatalytic activity for glucose detection on the present electrochemical sensing platform.

The forced convection of fluids has been investigated by numerous researchers, both experimentally and numerically. A good understanding of characteristics of nanofluid flowhas thoroughly been investigated in these studies. Since the nanoparticles behave more like a single-phase fluid than a solid–liquid mixture, it is assumed that nanofluids are ideally suited in the applications as their usage causes little or no penalty in pressure drop. In recent years, many researchers have tried to fill the gaps on this subject in the literature. To meet the demand for improving the performance of heat transfer equipment, re-examination of the individual components is considered to be essential. The addition of the nanoparticles to the base fluid is one of the significant issues for the optimal performance of heat transfer systems. This paper reports on most of the forced convective heat transfer literature occurring both in-tubes and in-channels regarding the use and preparation of nanofluids. The peer reviewed papers published in citation index journals up to 2012 have been selected for review in the paper. Classification of the papers has been performed according to the publication years. The critical information on the theoretical, experimental and numerical works is presented comprehensively for each paper.