Kawwam M.,CNRS Laboratory of Physical Chemistry of Luminescent Materials |
Kawwam M.,King Abdullah Institute for Nanotechnology |
Alharbi F.,King Abdulaziz City for Science and Technology |
Alharbi F.,Qatar Environment and Energy Research Institute |
And 3 more authors.
Applied Surface Science | Year: 2012
Cupric oxide (CuO) films were prepared on various substrates by the pulsed laser deposition (PLD) technique to investigate their effects on surface morphology. As the substrate temperature decreased, the film surface roughness was also observed to decrease. This trend was also correlated with the polycrystalline structure of the films. Deposition at low pressures produced greater surface roughness because larger crystallites emerged from the surface, while higher oxygen pressure under an adjusted target-substrate distance produced smaller crystallites and a smoother film surface. Reducing the laser energy density led to lower densities and smaller micro-liquid droplets formed on the surfaces. The presented results could be useful for better understanding the effect of process parameters control on CuO film morphology. It could also serve as a reference for the fabrication of CuO-based devices, in which the surface quality of the CuO films is highly important. © 2012 Elsevier B.V.
Ahamed M.,King Abdullah Institute for Nanotechnology |
Khan M.A.M.,King Abdullah Institute for Nanotechnology |
Alhadlaq H.A.,King Saud UniversityRiyadh11451 Saudi Arabia
Environmental Toxicology | Year: 2015
Because of unique optical behavior gold nanorods (GNRs) have attracted attention for the application in biomedical field such as bio-sensing, bio-imaging and hyperthermia. However, toxicological response of GNRs is controversial due to their different surface coating. Therefore, a comprehensive knowledge about toxicological profile of GNRs is necessary before their biomedical applications. First time, we investigated the toxic response of GNRs coated with platinum (GNRs-Pt) in human breast carcinoma (MCF-7) cells. Platinum coating further improves the optical and catalytic properties of GNRs. Assays such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT), neutral red uptake (NRU) and lactate dehydroganase (LDH) assays have shown that GNRs-Pt induced cytotoxicity at very low exposure levels (0.1-0.8 μg mL-1). Accumulation of cells in SubG1 phase and low mitochondrial membrane potential (JC-1 probe) in treated cells suggest that GNRs-Pt induced cell death via apoptotic pathway. Quantitative real-time PCR data demonstrated that mRNA expression of apoptotic genes (bax, caspase-3 and caspase-9) were up-regulated while anti-apoptotic gene bcl-2 was down-regulated in cells exposed to GNRs-Pt. We further observed the higher activity of caspase-3 and caspase-9 enzymes in GNRs-Pt treated cells supporting mRNA data. Moreover, N-acetyl cysteine (NAC) significantly attenuated the ROS generation and cytotoxicity induced by GNRs-Pt in MCF-7 cells suggesting that ROS might plays a crucial role in GNRs-Pt induced toxicity. This study warns of possible toxicity of GNRs even at very low exposure levels. Further investigations needed to explore potential mechanisms of this low dose toxicity phenomenon. © 2015 Wiley Periodicals, Inc.
Feng P.,University of Puerto Rico at San Juan |
Sajjad M.,University of Puerto Rico at San Juan |
Li E.Y.,University of Puerto Rico at San Juan |
Zhang H.,Globalfoundrie |
And 3 more authors.
Beilstein Journal of Nanotechnology | Year: 2014
We report studies of the surface fringe structures and tunable bandgap width of atomic-thin boron nitride nanosheets (BNNSs). BNNSs are synthesized by using digitally controlled pulse deposition techniques. The nanoscale morphologies of BNNSs are characterized by using scanning electron microscope (SEM), and transmission electron microscopy (TEM). In general, the BNNSs appear microscopically flat in the case of low temperature synthesis, whereas at high temperature conditions, it yields various curved structures. Experimental data reveal the evolutions of fringe structures. Functionalization of the BNNSs is completed with hydrogen plasma beam source in order to efficiently control bandgap width. The characterizations are based on Raman scattering spectroscopy, X-ray diffraction (XRD), and FTIR transmittance spectra. Red shifts of spectral lines are clearly visible after the functionalization, indicating the bandgap width of the BNNSs has been changed. However, simple treatments with hydrogen gas do not affect the bandgap width of the BNNSs. © 2014 Feng et al.
Mantey K.,University of Illinois at Urbana - Champaign |
Nayfeh M.H.,University of Illinois at Urbana - Champaign |
Al-Hreish B.,Nanosi Advanced Technoloies Inc. |
Boparai J.,Nanosi Advanced Technoloies Inc. |
And 5 more authors.
Journal of Applied Physics | Year: 2011
We used wet treatment to immobilize luminescent silicon nanoparticles on industrial glass fibers to impart optical and chemical functions to the fiber. Carpets or pads consisting of thousands of fibers are processed in parallel, enhancing the sensitivity of detection and the sampled volume. Treated pads exhibit strong luminescence, characteristic of the luminescence of the particles; showing no shift, broadening, or reduction of quantum efficiency. We demonstrate that drawing material by the pad due to physical adsorption can be reversed. We also demonstrate that allylamine can be covalently attached by photoinduced irradiation reactions, which results in imprinting the amine emission spectrum, providing spectral recognition. The imprint accompanied with a blue-shifting of the luminescence spectrum of the probe, allowing examination of the effect of termination on the nanoparticle structure. The shift is found to be consistent with an increase in the bandgap of the Si nanoparticle and is consistent with Quantum Monte Carlo calculations. In addition to sampling, the nano probe pad has the potential to enable a variety of biomedical applications through subsequent attachment. © 2011 American Institute of Physics.
Dhiman P.,Himachal Pradesh University |
Batoo K.M.,King Abdullah Institute for Nanotechnology |
Kotnala R.K.,National Physical Laboratory India |
Singh M.,Himachal Pradesh University
Micro and Nano Letters | Year: 2012
A report is presented on the structural, electrical, optical and magnetic properties of Fe-doped ZnO nanoparticles synthesised by the solution combustion technique. Structural characterisation by X-ray diffraction confirmed the phase purity of the samples. Surface morphology studied by scanning electron microscope revealed a cubic-type shape of grains. Energy dispersive X-ray spectroscopy analysis confirmed the elemental composition. Less value of DC electrical conductivity and increased bandgap for doped ZnO from UV-Vis studies confirmed change in the defect chemistry of the ZnO matrix. However, varied synthesis process results in ferromagnetic behaviour for doped ZnO nanoparticles. © 2012 The Institution of Engineering and Technology.
Ali M.,King Saud University |
Ali M.,King Abdullah Institute for Nanotechnology |
Zeitoun O.,King Saud University |
Zeitoun O.,King Abdullah Institute for Nanotechnology |
Almotairi S.,King Saud University
International Journal of Thermal Sciences | Year: 2013
Experimental investigation on natural convection heat transfer has been carried out inside vertical circular enclosures filled with Al 2O 3 nanofluid with different concentrations; 0.0%, 0.85% (0.21%), 1.98 (0.51%) and 2.95% (0.75%) by mass (volume). Two enclosures are used with 0.20 m inside diameter and with two different aspect ratios. The bottom surface of the enclosure is heated using a constant heat flux flexible heater while the upper surface is cooled by an ambient air stream. Various uniform heat fluxes have been used to generate the natural convection heat transfer data. The average Nusselt number is obtained and correlated with the modified Rayleigh number at each concentration ratio of the nanofluid. The average Nusselt number is obtained for each enclosure and correlated with the modified Rayleigh number using the concentration ratio as a parameter. The results show that the heat transfer coefficient increases as the concentration increases up to a specific value of the concentration and then it decreases as the concentration continues to increase compared to the basic fluid of pure water. Furthermore, a general correlation is obtained using the volume fraction and the aspect ratio as parameters. © 2012 Elsevier Masson SAS. All rights reserved.
Ghannam T.,King Abdullah Institute for Nanotechnology
Applied Optics | Year: 2013
This paper investigates a specific kind of solitary pulse, the modulated zero-area (MZA) solitary pulse, when propagating within MgO photonic bandgap medium doped with silver nanoparticles (NPs). It will be shown that two coupled MZA pulses do propagate unattenuated within this medium but for a certain combination of the dipole moments and the density of the NPs. More important, and in contrast to the other kinds of solitary pulses, one of the two MZA pulses exhibits a slowing in its group velocity in comparison to the other one, depending on the amplitudes of the components of the dipole moments of the NPs that are in resonance with the two MZA pulses. With this particular feature, the system has the potential of working as an all-optical switch. © 2013 Optical Society of America.