Saima Khan

Three-dimensional rotating flow of MHD single wall carbon nanotubes over a stretching sheet in presence of thermal radiation

In this article the modeling and computations are exposed to introduce the new idea of MHD three-dimensional rotating flow of nanofluid through a stretching sheet. Single wall carbon nanotubes (SWCNTs) are utilized as a nano-sized materials while water is used as a base liquid. Single-wall carbon nanotubes (SWNTs) parade sole assets due to their rare structure. Such structure has significant optical and electronics features, wonderful strength and elasticity, and high thermal and chemical permanence. The heat exchange phenomena are deliberated subject to thermal radiation and moreover the impact of nanoparticles Brownian motion and thermophoresis are involved in the present investigation. For the nanofluid transport mechanism, we implemented the Xue model (Xue, Phys B Condens Matter 368:302–307, 2005). The governing nonlinear formulation based upon the law of conservation of mass, quantity of motion, thermal field and nanoparticles concentrations is first modeled and then solved by homotopy analysis method (HAM). Moreover, the graphical result has been exposed to investigate that in what manner the velocities, heat and nanomaterial concentration distributions effected through influential parameters. The mathematical facts of skin friction, Nusselt number and Sherwood number are presented through numerical data for SWCNTs.

Polyethylene Oxide Nanofibers as Ultraviolet Sensors

Using the electrospinning technique, we have prepared [Ru (pic) 2 (dmso) 2 ] doped-polyethylene oxide nanofibers for ultraviolet sensing. The diameter of the as-prepared fibers is in the range of 1μm-100nm. These fibers change color from pale yellow to orange when exposed to ultraviolet light (wavelength∼350nm) and return to their original color after approximately 2-3 days. The intensity of the color increases with an increased time of exposure to UV. The color changing behavior in the nanofibrous mat is almost the same as that in cast films prepared from the same solutions. The scanning electron microscope (SEM) studies of the fibers show that the morphology of the fibers remains unchanged after exposure to UV.

ZnO Nanofibers Doped with Ga, In and Er Fabricated with Electrospinning Technique

ABSTRACT ZnO nanofibers doped with Ga, In and Er metals have been fabricated by the electrospinning technique. The average diameter of the fibers was in the range of 0.5-2 µm and the length up to several meters. After spinning fabrication step the samples were dried out and annealed at 900 °C in air. Room temperature photoluminescence (PL) spectra measured for undoped and In- and Ga-doped ZnO fiber samples exhibit only a strong near-band edge (NBE) emission at ~380 nm with a very weak green band at 525 nm. In contrast, the PL spectrum of Er-doped ZnO fibers shows a very weak NBE and strong green emission band at ~550 nm at 300 K. The electrospinning mechanism used for the fabrication of nanofibers was found to be productive, simple and easy to implement regardless of the doping type and concentration. INTRODUCTION Quasi one-dimensional (1D) nanomaterials, including nanowires, have attracted intensive research interest due to their large specific surface areas and quantum confinement effects [1]. These nanostructures are expected to play a critical role both as interconnects and functional units in the fabrication of nanoscale electronic, optoelectronic, and electromechanical devices [1,2]. Several different methods have already been employed to synthesize 1D nanostructures, including but no limited to physical and chemical vapor deposition [3-5] solvothermal technique [6], solution phase route [7], and electrodeposition technique [8]. One of the problems with nanowires is that the aspect ratio (length to diameter) is not large, making spatial manipulation and assembly difficult. Electrospinning, on the other hand, is a useful technique for fabrication of nano- and microfibers with diameters as small as a few tens of nanometers and a few meters long [9]. We have made an effort to fabricate ZnO nano- and microfibers from various starting material sources using a home build electrospinning apparatus. In this report we concentrate on fabrication of undoped ZnO and In-, Ga-, Er-doped ZnO fibers, their morphology and room temperature luminescence.