International Journal Of Nanoscience and Nanotechnology
Volume:8 Issue: 1, Winter 2010

In this study, Salmonella Typhimurium bacteria removal from polluted water has been investigated using multiwall carbon nanotubes arrays. Experimental results reveal that the contact time, the bacterial concentration and the weight of multiwall carbon nanotubes arrays have positive significant effects on the bacteria removal efficiency. Increasing the contact time and the weight of multiwall carbon nanotubes arrays enhances the removal efficiency which can be the result of the aggregation increase between bacteria cells and carbon nanotubes. Scanning electron microscopy images demonstrate that the multiwall carbon nanotubes arrays capture the bacteria cells by the sieve mechanism without any specific effect on the bacteria cell morphology. Furthermore, the impact of the compressing and crushing of carbon nanotubes arrays on the bacteria cell removal efficiency were studied. Results show that crushing process enhances the bacteria removal efficiency and also increases the loss of carbon nanotube arrays by transportation with water. However, compressing process does not have any significant effect on the bacteria removal efficiency in comparison to the primary samples, and also decreases the loss of carbon nanotubes. These observations suggest that compressed carbon nanotubes arrays can be an appropriate choice for separation of salmonella bacteria from polluted water.

Crystalline antimony sulfide (Sb2S3) with nanorods morphology was successfully prepared via hydrothermal method by the reaction of elemental sulfur, antimony and iodine as starting materials with high yield at 180°C for 24h.Using oxidation reagents like iodine as an initiator of redox reaction to prepare Sb2S3 is reported for first time. Crystal growth of Sb2S3 was done by increasing reaction time up to 3 days. The powder X-ray diffraction pattern shows the Sb2S3 crystals belong to the orthorhombic phase with calculated lattice parameters of a=1.120nm, b=1.128nm and c=0.383nm. The quantification of energy dispersive X-ray spectrometry analysis peaks give an atomic ratio of 2:3 for Sb:S. Scanning electron microscopy (SEM) images show that the diameter of nanorods was around 250-380 nm and their length was less than 3 μm, respectively. After crystal growth due to increasing the reaction time, diameter of nanorods was reached to about 500-700 nm and their length extended to about 6 μm. UV-Vis analysis and emission spectra indicates that band gap of Sb2S3 is around 2.82eV, indicating a considerable blue shift relative to the bulk. Moreover, formation mechanism of Sb2S3 nano structure was proposed and the effect of reaction time on the growth of nano materials was also investigated.

Ni-P and Ni layers multilayer coatings were applied to AZ31 magnesium alloy utilizing electroless and electrodeposition procedures. The aim of the project was to decrease cracks and increase corrosion resistance of the coatings. In order to compare the coatings, the effect of single layer electroless Ni-P coatings with different thicknesses was also investigated. The microstructure and phase composition of the coatings were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The results showed that increase in the thickness of the single layer coatings was not an effective solution to inhibit the reaction of magnesium with plating bath during electroless process. In this regard, magnesium was detected on the surface of the single layer coatings. The application of a thin electroplated Ni layer between two electroless layers could inhibit the reaction of magnesium with plating bath during electroless process, which resulted in improving the corrosion resistance of the coatings.

In this article CuO/water nanofluid was synthesized by using polyvinylpyrolidone (PVP) as the dispersant. Thenanofluid stability period and the heat transfer enhancement were determinedby measuring the thermal conductivities. To study the nano-fluid stability, zeta (ζ) potential, and absorbency were measured under different pH values and PVP surfactant concentrations; also thermal conductivity enhancement was measured based on different volume fraction of CuO nanoparticles and temperature. The results showed that the nano-fluid with PVP surfactant has a good stability of about a week in the optimum pH and PVP concentration which are 8 and 0.095,respectively. Furthermore, in the abovementioned concentration of pH and PVP, optimum CuO volume fraction of 6% was obtained, in which, the thermal conductivity enhancement is 17% at 25oC. Finally, with changing temperature at optimum values (for PVP surfactant and CuO nanoparticles), 31% increase in thermal conductivity was obtained at 50oC.

Contact mechanics is related to the deformation study of solids that meet each other at one or more points. The physical and mathematical formulation of the problem is established upon the mechanics of materials and continuum mechanics and focuses on computations involving bodies with different characteristics in static or dynamic contact. Contact mechanics gives essential information for the safe and energy efficient design of various systems. During manipulation process, contact forces cause deformation in contact region which is significant at nano-scale and affects the nano-manipulation process. Several nano-contact mechanics models such as Hertz, DMT, JKRS, BCP, MD, COS, PT, and Sun have been applied as the continuum mechanics approaches at nano-scale. Recent studies show interests in manipulation of biological cells which have different mechanical properties. Low young modulus and consequently large deformation makes their manipulation so sensitive. In this article small deformation contact mechanics models are used for biological cell, in air and liquid environment, then results will be compared with Tatara contact mechanics model which has been developed for hyperelastic materials with large deformation. Since biological cells are mostly modeled as viscoor hyper-elastic materials, this model will be more compatible with their condition. FE simulation has been done to investigate the applicability of these models and finite element approach in different ranges of deformations.

This study aims at exploring an effective route in the in situ graft polymerization of aniline from Fe3O4 nanoparticles. To this goal, Fe3O4 magnetic nanoparticles were prepared by coprecipitation method using ammonia solution as the precipitating agent, and were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thereafter, polyaniline (PANI) grafted magnetite nanoparticles were successfully synthesized by the in situ chemical oxidative polymerization of aniline monomer by ammonium peroxodisulfate (APS) from the surfaces of the aminopropyl magnetite nanoparticles with a dispersion polymerization method. The chemical grafting of polyaniline from magnetite nanoparticles were confimed by using FT-IR, ultraviolet-visible (UV-Vis) spectroscopy and thermogravimetric analysis (TGA), and also the dispersion state of Fe3O4 nanoparticles in the polyaniline matrix was examined by TEM. In comparison to the pure polyaniline, the polyaniline/Fe3O4 nanocomposite shows to have higher decomposition temperature.