The water-vapor sorption processes in nanoporous MgO-Al2O3 ceramics are studied with positron annihilation lifetime (PAL) spectroscopy employing positron trapping and positronium (Ps)-decaying modes. It is demonstrated that the longest-lived components in the four-term reconstructed PAL spectra with characteristic lifetimes near 2 and 60-70 ns can be, respectively, attributed to ortho-positroni...

We present an Al2O3 dielectric layer on molybdenum disulfide (MoS2), deposited using atomic layer deposition (ALD) with ozone/trimethylaluminum (TMA) and water/TMA as precursors. The results of atomic force microscopy and low-energy ion scattering spectroscopy show that using TMA and ozone as precursors leads to the formation of uniform Al2O3 layers, in contrast to the incomplete coverage we ob...

Fluoride removal from aqueous solutions using a-Al2O3 as an adsorbent was investigated through adsorption and electrokinetic studies, using two different initial fluoride concentrations relevant to fluoride contents in drinking water, namely 3 and 10 mg/L. Maximum fluoride removal was achieved between pH 5 and 6 at 258C. Adsorption at both pH 5 and 9 correlates to the Langmuir isotherm. The poi...

This paper shows the research work on heat exchanger using nano fluid. In this paper we are using compact heat exchanger as heat transferring device while Al2O3 as a nano fluid. The effect of the nano fluids on compact heat exchanger is analyzed by using ε –NTU rating numerical method on turbo-charged diesel engine of type TBD 232V-12 cross flow compact heat exchanger radiator with unmixed flui...

Our group recently reproduced the water-assisted growth method, so-called "SuperGrowth", of millimeter-thick single-walled carbon nanotube (SWNT) forests by using C2H4/H2/H2O/Ar reactant gas and Fe/Al2O3, catalyst. In this current work, a parametric study was carried out on both reaction and catalyst conditions. Results revealed that a thin Fe catalyst layer (about 0.5 nm) yielded rapid growth ...

In this study, the nanofluids are produced by dispersing Al2O3 nanoparticles in the H2O/CH3OH binary mixtures using an ultrasonic equipment. Solid Sodium Chlorides (NaCl) with a fixed mass fraction are dissolved in the binary mixture for CO2 absorption. The main objective of this paper is to measure the thermal conductivity of the Al2O3 nanofluids using the transient hot-wire method. The experi...

Using previous results for the equilibrium geometries of stoichiometric (Al2O3)n clusters as models for non ideal alumina surfaces, we obtain, from ab-initio total energy LCAO calculations, the corresponding relaxed structures of the complexes H2O–(Al2O3)n with n ≤ 7. Depending on the initial position of the water molecule relative to the cluster site, the complex evolves to different equilibri...

A first-principles study of the vibrational modes of PbTiO3 in the ferroelectric tetragonal phase has been performed at all the main symmetry points of the Brillouin zone ~BZ!. The calculations use the local-density approximation and ultrasoft pseudopotentials with a plane-wave basis, and reproduce well the available experimental information on the modes at the G point, including the LO-TO spli...

Hydrogen is an important chemical in many industries and it is expected to become one of the major fuels for energy generation in the future. Unfortunately, hydrogen does not exist in its elemental form in nature and therefore has to be produced from hydrocarbons, hydrogen-containing compounds or water. Above its critical point (374.8C and 22.1MPa), water has lower density and viscosity, and a ...

in this paper, overall heat transfer coefficient and friction factor of water based γ-al2o3 nanofluid in a double tube counter flow heat exchanger have been measured experimentally under turbulent flow condition. for better dispersion of γ-al2o3 nanoparticles in distilled water, magnetic stirrer and ultrasonic vibrator (with a power of 240 kw and frequency of 35 khz) were implemented. the stabi...