Energy and economic analysis of evaporative vacuum easy desalination system with brine tank

Journal of Thermal Analysis and Calorimetry - Nowadays, the freshwater is one of the most critical issues for humans. In this regard, desalination systems can be beneficial. In this research, at...     

Comparison of the performance of different modified graphene oxide nanosheets for the extraction of Pb(II) and Cd(II) from natural samples

Graphene nanosheets were modified with amino groups and the resulting material was used as a sorbent for the extraction of cadmium and lead ions. The nanosheets were characterized by IR spectroscopy, transmission electron microscopy, thermal gravimetric analysis and elemental analysis. The effects of sample pH, eluent parameters (type, concentration and volume of eluent), flow rates (of both sample and eluent), and of a variety of other ions on the efficiency of the extraction of Cd(II) and Pb(II) were optimized. Following solid phase extraction, the elements were determined by FAAS. The limits of detection are <0.9 μg L^?1 for Pb(II) and <5 ng L^?1 for Cd(II). The relative standard deviations are <2.2 %. The method was validated by analyzing several certified reference materials and was then used for Pb(II) and Cd(II) determination in natural waters and vegetables.

The solution of Pennes' bio-heat equation with a convection term and nonlinear specific heat capacity using Adomian decomposition

Journal of Thermal Analysis and Calorimetry - Pennes' bio-heat equation is the most widely used equation to analyze the heat transfer phenomenon associated with hyperthermia and cryoablation...     

Analysis of amplification properties of a photonic crystal fiber

In this work, effects of geometrical parameters and dopant concentration on amplification performance of Yb doped photonic crystal fiber amplifiers (YDPCFAs) are investigated. To this end, numerical results obtained from fully vectorial effective index method, are combined with conventional rate equations. The variation of the normalized frequency of the photonic crystal fiber with respect to air filling factor for different air hole spacing are depicted. Using obtained results, the single-mode region at signal and pump wavelengths are determined. In addition, the influence of dopant concentration on the maximum gain and optimum length are investigated. It is shown that by changing photonic crystal fiber cross-section parameters such as pitch and air filling factor, rather than increasing dopant concentration, one can obtain a higher gain at shorter optimum length. These results are useful for the design of YDPCFAs with less nonlinearity effects such as cooperative up conversion and Yb³⁺ ion quenching.     

Application of a characterized difference-frequency laser source to carbon monoxide trace detection

A tunable continuous wave(cw) mid-infrared(MIR) laser based on difference-frequency generation(DFG) in a 1.5-cm long AgGaS2 nonlinear crystal for trace gas detection is reported.Two visible and near-infrared diode lasers were used as pump and signal sources.The MIR-DFG laser was tunable in a wavelength range of 4.75 μm-4.88 μm.The phase-matching(PM) condition was non-critically achieved by adjusting the temperature of the crystal for fixed pairs of input pump and signal wavelengths.The required PM temperatures of the generated MIR-DFG wavelengths have been calculated by using three sets of recent Sellmeier equations and the temperature-dispersion equations of AgGaS2 given by Willer U,et al.(Willer U,Blanke T and Schade W 2001 Appl.Opt.40 5439).Then the calculated PM temperatures are compared with the experimental values.The performance of the MIR-DFG laser is shown by the trace detection of the P(16) carbon monoxide(12C16O) absorption line in a laboratory-fabricated absorption cell.The enhanced sensitivity of about 0.6×10 4 was obtained through the long path absorption provided by consecutive reflections between coated cylindrical mirrors of a constructed cell.     

Coherent states for the Kepler–Coulomb problem on a sphere

An algebraic approach to Kepler problem in a curved space is introduced. By using this approach, the creation and annihilation operators associated to this system and their algebra are calculated. These operators satisfy a deformed Weyl–Heisenberg algebra which can be assumed as a deformed su(2)$\mathfrak{s}\mathfrak{u}\left(2\right)$ algebra. By using this fact, the nonlinear coherent states of this system are constructed. The scalar product and Bargmann representation of this family of nonlinear coherent states are constructed. The present contribution shows that these nonlinear coherent states possess some non-classical features which strongly depend on the Kepler coupling constant and space curvature. Depending on the non-classical measures, the smaller the curvature parameter, the more the non-classical features. Moreover, the stronger Kepler constant provides more non-classical features.     

Growth and Physical Properties of CdS/TiO_2 Bilayer by Plasma-Based Method

The titanium oxide(TiO_2) nanotubes have attracted attention for their use in dye-sensitized solar cells as photoanode. In this study semiconducting cadmium sulfide(CdS) nanoparticles are grown on top opened TiO_2 nanotubes arrays by radio-frequency magnetron sputtering. X-ray diffraction, scanning electron microscopy,transmission electron microscopy and diffuse reflection spectra are used to study structural, morphological and optical properties of the CdS/TiO_2 bilayer.