INTERNATIONAL NANO LETTERS (INL)
Year:2014 | Volume:4 | Issue:3|Papers Count:9

An equilibrium molecular dynamics simulation is applied to investigate the thermal properties of a singlewalled carbon nanotube/poly (phenylenesulfone) as nanocomposite material. Cohesive energy density and the Hildebrand solubility parameter of pure poly (phenylenesulfone) and nanocomposite are calculated to compare the thermal analysis of them. The results indicate that carbon nanotube/poly (phenylenesulfone) nanocomposites are thermally stable than pure poly (phenylenesulfone); however, poly (phenylenesulfone) is a thermally stable polymer. This means carbon nanotube can further improve thermal properties of thermally stable polymer.

The increasing use of zinc oxide (ZnO) nanoparticles in sunscreens and other cosmetic products demands a risk assessment that has to be done in toxicological studies. Such investigations require profound knowledge of the behavior of ZnO in cell culture media. The current study was performed to get well-dispersed suspensions of a hydrophilic (ZnO-hydro) and a lipophilic coated (ZnO-lipo) ZnO nanomaterial for use in in vitro tests. Therefore, systematic tests were carried out with common dispersants (phosphate, lecithin, proteins) to elucidate chemical and physical changes of ZnO nanoparticles in water and physiological solutions (PBS, DMEM). Nonphysiological stock suspensions were prepared using ultrasonication. Time-dependent changes of pH, conductivity, zeta potential, particle size and dissolution were recorded. Secondly, the stock suspensions were added to physiological media with or without albumin (BSA) or serum (FBS), to examine characteristics such as agglomeration and dissolution. Stable stock suspensions were obtained using phosphate as natural and physiological electrostatic stabilizing agent. Lecithin proved to be an effective wetting agent for ZnO-lipo. Although the particle size remained constant, the suspension changed over time. The pH increased as a result of ZnO dissolution and formation of zinc phosphate complexes. The behavior of ZnO in physiological media was found to depend strongly on the additives used. Applying only phosphate as additive, ZnOhydro agglomerated within minutes. In the presence of lecithin or BSA/serum, agglomeration was inhibited. ZnO dissolution was higher under physiological conditions than in the stock suspension. Serum especially promoted this process. Using body-related dispersants (phosphate, lecithin) non-agglomerating stock suspensions of hydrophilic and lipophilic ZnO were prepared as a prerequisite to perform meaningful toxicological investigation. Both nanomaterials showed a non-negligible dissolution behavior that strongly depended on the surrounding conditions. Agglomeration of ZnO particles in physiological media is a complex function of particle coating, used dispersants and serum proteins if supplemented. The present study gives a clear guideline how to prepare and handle suspensions with ZnO for in vitro testing and allows the correlation between the chemical-physical particles behavior with findings from toxicological tests.

Because of the classification of the nickel compounds as carcinogenic substances, there is a need for in vivo tests to nickel nanoparticles (NiNPs) for observing their effects on health experimentally. Spherical NiNPs with 10 nm in diameter and 75 ppm concentration were applied for investigating their toxicities within male albino mice as an in vivo model. We randomly made sham group, control group, and 75 ppm group (with five animals in each group). Then, the nanoparticles were injected into mice intraperitonealy for 7 days and after that their lungs, liver, and spleen were removed for histopathological observations. At the end of the test, section microscopic observations of liver, spleen, and lung in sham and control groups showed normal tissues but these tissues underwent significant abnormal effects in 75 ppm group. NiNPs can cause undesirable effects in lungs, liver, and spleen tissues with same condition of this study.

Nanotechnology has been used in many applications and new possibilities are discovered constantly. Recently, a renewed interest has risen in the application of nanotechnology for the upstream petroleum industry, such as exploration, drilling, production and distribution. In particular, adding nanoparticles to fluids may significantly benefit enhanced oil recovery and improve well drilling, such as changing the properties of the fluid, wettability alternation of rocks, advanced drag reduction, strengthening sand consolidation, reducing the interfacial tension and increasing the mobility of the capillary-trapped oil. In this study, we focus on the roles of clay and silica nanoparticles in adsorption process on reservoir rocks. Polymer-flooding schemes for recovering residual oil have been in general less satisfactory due to loss of chemicals by adsorption on reservoir rocks, precipitation, and resultant changes in rheological properties. Adsorption and rheological property changes are mainly determined by the chemical structure of the polymers, surface properties of the rock, composition of the oil and reservoir fluids, the nature of the polymers added and solution conditions such as salinity, pH and temperature. Because this method relies on the adsorption of a polymer layer onto the rock surface, a deeper understanding of the relevant polymer–rock interactions is of primary importance to develop reliable chemical selection rules for field applications. In this paper, the role of nanoparticles in the adsorption of water-soluble polymers onto solid surfaces of carbonate and sandstone is studied. The results obtained by means of static adsorption tests show that the adsorption is dominated by the nanoclay and nanosilica between the polymer molecules and the solid surface. These results also show that lithology, brine concentration and polymer viscosity are critical parameters influencing the adsorption behavior at a rock interface. On the other hand, in this study, the focus is on viscosity, temperature and salinity of solutions of polyacrylamide polymers with different nanoparticle degrees and molecular weight. The adsorption of nanopolymer solution is always higher in carbonated stones than in sandstones, and polymer solutions containing silica nanoparticles have less adsorption based on weight percent than similar samples containing clay. Based on the area of contact for stone, this behavior is the same regarding adsorption.

To raise the need of new precursors in the synthesis of NiO nanoparticles, mononuclear nickel (II) Schiff base complexes, viz. Ni (salbn) and Ni (Me2-salpn), were employed as precursor in solid-state thermal decomposition. Structure, purity and morphology of these nanoparticles have been examined by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy (TEM). TEM analysis reveals that the synthesized nanoparticles have cubic particles with an average diameter of around 5–15 nm. This method is simple, less costly, and fast and safe for production of NiO nanoparticles in industrial applications.

The synthesis of polyaniline/single-wall nanotube, polyaniline/multi-wall nanotube and polyaniline/single-wall nanotube/graphen nanosheets nanocomposites by in situ polymerization are reported in this study. The substrates were treated with a mixture of concentrated sulfuric acid and concentrated nitric acid before usage to functionalize with carboxylic and hydroxyl groups. Aniline monomers are adsorbed and polymerized on the surface of these fillers. Structural analysis using scanning electron microscopy showed that nanomaterials dispersed into polymer matrix and made tubular structures with diameters several tens to hundreds nanometers depending on the polyaniline content. These nanocomposites can be used for production of excellent electrode materials applications in high-performance supercapacitors.

In this paper, the effects of carbon nanotubes (CNTs) were studied as supports for the synthesis of MnFe2O4 nanocomposite. The synthesis of nanocomposite powder MnFe2O4/CNTs was performed by direct precipitation method in aqueous solution. The prepared samples were analyzed by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The results represent the considerable change in the MnFe2O4 nanoparticle size and also the morphology of MnFe2O4/CNT nanocomposite powder from agglomerative into nanorod in shape.

In this study, anatase titanium dioxide nanoparticles were successfully prepared by a sol–gel method using two different precursors, titanium isopropoxide and titanium butoxide. Hydrochloric acid or nitric acid was added to adjust the pH of the solution. The sols obtained were dried at 80 oC and calcined at 450 oC for 3 h. The nanostructures were characterised by scanning electron microscopy, FTIR and ultraviolet–visible spectroscopy. The phase transformations were investigated by an X-ray diffractometer. Highly crystalline anatase titania nanoparticles could be obtained through the controlled hydrolysis reaction rate. The sizes of synthesized particles were in the range 5–13 nm, i.e.9 nm on an average and with a regular shape. The size of nanoparticles was not affected by the choice of precursor. The broad view of the samples prepared using titanium isopropoxide showed film-like structures, whereas the samples prepared using titanium butoxide showed spherical granules. A red shift of 0.13 eV was observed in the band gap in the case of non-spherical particles compared to spherical ones.

In this work we investigate the n-type single halo implantation in channel of lightly doped drain and source CNTFET (SH-LDDS-CNTFET) and propose the n-type double linear halo implantation in the channel of LDDS-CNTFET. These transistors are simulated with a non-equilibrium Green’s function method. We demonstrate that in the proposed structure the ¦T at the VGS ranges of 0–0.25 V and more than 0.42 V is much higher compared to the LDDS-CNTFET and SH-LDDS-CNTFET and the SH-LDDS-CNTFET, respectively. Finally, simulations demonstrate that the ¦T of the proposed transistor is more than the LDDS-CNTFET at a wide range of VGS, whereas the ¦T of SH-LDDS-CNTFET is more than the LDDSCNTFET for narrow ranges of VGS.