EDXRF analysis of suspended particulate matter (SPM) from residential and industrial areas in Cairo,Egypt

Due to the remarkable increasing of the mass concentrations of suspended particulate matter (SPM) as an air pollution indicator in Greater Cairo‐Egypt, regular sampling during autumn 2014 and winter 2014/2015 seasons has been performed from industrial and residential areas. It was found that the average mass concentrations of the SPM collected from residential and industrial areas are equal to 531 ± 198 and 912 ± 230 μg/m³, respectively. These quantities are much higher than the maximum allowance level, especially for the industrial area. By utilizing three secondary targets, energy dispersive x‐ray fluorescence working under vacuum environment was used for elemental analysis of 19 elements namely; Na, Al, Si, S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Pb, Se, Br, Rb, and Sr. The present optimized selective excitation energy dispersive x‐ray fluorescence analysis has considerably enhanced the analytical range with respect to our previous similar studies, including low Z elements such as Na, Al, S, and Cl and attaining lower detection limits in the range of ng/m³. Remarkable high elemental concentrations were determined for most of the detected elements from the industrial area samples, strongly indicating the influence of the industrial and anthropogenic activities. The average percentages of the mass concentration of the detected inorganic elements account only for 3.2% and 10.5% of the total mass concentration collected from the residential and industrial areas, respectively, thus directly indicating that the content of organic pollutants in SPM is the dominant contribution.     

Propagation of p-polarized waves in a linearly graded index film surrounded by negative index materials

The theory of step-index waveguides is well-established. Most practical slab waveguide structures have a graded-index profile. The basic properties of graded-index planar waveguide structures are similar to those of step-index waveguides with subtle differences. The most common types of graded-index slab waveguides are linearly and exponentially graded-index profiles. We here treat linearly graded-index slab waveguide. In this work, a three-layer waveguide structure with linearly graded-index film is considered. We assume three structures: the first structure comprises a left-handed material (LHM) cladding, the second structure contains a LHM substrate layer and the third has a LHM cladding and substrate. Closed-form expressions for electric and magnetic fields and the characteristic equation are derived. The three normalized parameters: the asymmetry coefficient (a), the normalized film thickness (V) and the normalized guide index (b) are used to study the dispersion properties of the proposed slab waveguide structure.     

The reduced detailed configuration accounting (RDCA) model for NLTE plasma spectral calculations

The purpose of this work is to continue development of a model to provide a fast and accurate in-line NLTE capability for calculating plasma spectral properties in large-scale radiation-transport hydrodynamic simulations. A method has recently been developed to transform the large detailed atomic models into very small models that can be used for fast in-line calculations. The reduced model is more accurate than the average-atom models conventionally used in such simulations. In the present work, spectra calculated with the reduced model are compared to the original detailed model and the average-atom model. The spectra of iron and gold plasmas under various plasma conditions are compared.     

Lead speciation of PM2.5 collected from Greater Cairo,Egypt and Zarqa,Jordan: An energy dispersive X-ray fluorescence and X-ray absorption near edge structure study

Fine aerosol particles with an aerodynamic diameter equal or less than 2.5 μm (PM_2.5) have been collected from two sites (residential and industrial) in Greater Cairo, Egypt and one site in Zarqa, Jordan. Based on the elemental quantitative analysis of PM_2.5 using energy dispersive X-ray fluorescence with Mo secondary target, Pb concentrations increased remarkably during winter season regardless of the sampling location. Moreover, it reached the maximum concentration at the industrial location of Greater Cairo, Egypt, and it equals 415 ± 485 ng/m³. The remarkable high standard deviation is due to the significant variation of Pb concentration from time to time during that winter season. Depending on the energy dispersive X-ray fluorescence results, specific PM_2.5 samples that have the highest concentration of Pb (two samples/location) have been selected for the X-ray absorption near edge structure measurements to estimate the oxidation state of Pb species. The X-ray absorption near edge structure measurements including 13 Pb references have been carried out at Pb-L₃ absorption edge (13.039 keV) using fluorescence mode. It was shown that PM_2.5 contains divalent and tetravalent lead in both industrial site in Greater Cairo, Egypt and urban site of Zarqa, Jordan although that of a residential area of Greater Cairo-Egypt is almost divalent lead.     

X-ray,optical, vibrational,electrical, and DFT study of the polymorphic structure of ethylenediammonium bis iodate α-C2H10N2(IO3)2 and β-C2H10N2(IO3)2

The interaction of ethylenediamine with iodic acid by the slow evaporation method at room temperature gives rise to the crystals of α-C₂H₁₀N₂(IO₃)₂ and β-C₂H₁₀N₂(IO₃)₂ denoted as α-EBI and β-EBI, respectively. The acentric crystal structures of both polymorphs that consist of [C₂H₁₀N₂]²⁺ cations and [IO₃]^? anions connected together by N–H…O hydrogen bonds are discussed and compared. The optical properties of both polymorphs were determined using UV-vis diffuse reflectance spectroscopy (DRS) showing a wide transparency windows. The DFT calculations using the mixed B3PW91/[6–31?+?(d, p), LanL2Dz] basis set of optimized geometries, dipole moment (μ), polarizability (α), first static hyperpolarizability (β), and population analysis were also reported. The experimental and theoretical IR and Raman spectra were compared, and the careful and complete assignment of the vibrational motions of both compounds was undertaken with the aid of potential energy distribution (PED) analysis. DSC and AC conductivity analysis revealed that α-C₂H₁₀N₂(IO₃)₂ and β-C₂H₁₀N₂(IO₃)₂ undergo a first-order phase transition around 360 K. The electrical σ_tot (ω, T) conductivity obeyed to Jonscher’s power law and the temperature dependence of the S(T) parameter showed that the electrical conductivity of both polymorph phases might be treated using the correlated barrier hopping (CBH) model.

     

On a mathematical model for hot carrier injection in semiconductors

We study a collisionless transport model for electrons in a semiconductor, and we perform an asymptotic analysis for low temperatures or large applied biases. We derive analytic relations for the built-in potential and for the current which flows through the structure.     

Weak solutions of the initial-boundary value problem for the Vlasov–Poisson system

In this paper we show the existence of a weak solution of the boundary value problem for the time dependent Vlasov–Poisson system. First, we regularize the system in order to apply a fixed-point theorem. Then we pass to the limit using an energy estimate.     

Existence and nonexistence results for higher-order semilinear evolution inequalities with critical potential

We prove nonexistence results for higher-order semilinear evolution equations and inequalities of the form

     

Le nombre des diviseurs d'un entier dans les progressions arithmétiques

Let d_k,?(n) be the function number of divisors of the integer n?1, in arithmetic progressions {?+mk}, with 1???k and ?,k coprime, and let F(n;k,?) defined as follows:

$\text{F(n;k,?)=}\text{ln}\text{d}{}_{\mathrm{k,?}}\text{(n)}\text{ln}\text{(?(k)}\text{ln}\text{n)}\text{ln}\text{2}\text{ln}\text{n}\text{.}$

In this Note, we study and give the structure of d_k,?-superior, highly composite numbers, which generalize those defined by S. Ramanujan. We prove that F(n;k,?) reaches its maximum among these numbers. We give it explicitly for k=2,…,13. This generalizes the study of Nicolas and Robin, in which the case k=1 is treated. To cite this article: A. Derbal, A. Smati, C. R. Acad. Sci. Paris, Ser. I 339 (2004).