Nano p-AgInTe2/n-CdS0.4Se0.6 heterojunction was constructed. The dark – current – voltage – characteristics of the prepared junction have been investigated in a temperature range from ~303 to 423 K. The operating conduction mechanism was found to be Pool-Frenkel emission for T > 323 K and V < +0.8 volt. The supposed band diagram of p-AgInTe2/n-CdS0.4Se0.6 heterojunction is exhibited. Analysis of the photovoltaic characteristic, at room temperature and under illumination of ~2.7 W/m2, lead to the determination of some solar cell parameters, such as; the short circuit current, the open circuit voltage, the fill factor and the power conversion efficiency.

The band gap energies of zinc-blende InNxAs1-x alloy as a function of its nitrogen composition have been calculated using the density functional theory. The results agree well with those obtained from experimental results. The minimum band gap energy of InNxAs1-x alloy obtained is 70 meV at its N composition of 0.45. The band gap bowing coefficient of InNxAs1-x alloy is obtained from the curve fitting of the simulated band gap energy versus the nitrogen composition, x. The band gap bowing coefficient of zinc-blende InNxAs1-x alloy is found to be 2.072 ± 0.236 eV. The energy band gap for InN is also correctly predicted from this calculation.

The paper presents a numerical simulation of the behaviour of SnO2:F/Si(N+)/Si(P) solar cells. The simulation addresses in particular the question of the role of the window layer SnO2:F for the device performance. As beginning step, the transparent conductive oxide of SnO2:F must be modelled in order to introduce its parameters in simulation codes. Two approaches were employed: one empirical by collecting the experimental data of spray deposited SnO2:F while the second one is theoretical by using models of highly degenerate wide band gap semiconductors. The second step consists in injecting the deduced parameters of fluorine doped tin oxide in simulation codes. We use two well-known photovoltaic simulation codes as PC1D and SCAPS 2.5. A comparative study of the results of structures SnO2:F/Si(N+)/Si(P) and Si(N+)/Si(P) have been done with a confirmation in enhancing the conversion efficiency by SnO2:F window layer addition.

The capacitance between any two arbitrary lattice sites of an infinite square network consisting of identical capacitors is studied analytically and numerically for a perturbed network. The perturbation is as a result of removing the bonds $(i_{0} j_{0})$ and $(k_{0} l_{0})$ from the perfect network. The equivalent capacitance is expressed in terms of the Lattice Green's Function (LGF) of the perturbed network. Solving Dyson's equation we express the LGF and the capacitance of the perturbed network in terms of those of the infinite perfect network. The asymptotic behavior of the perturbed capacitance is also studied. Finally, some numerical results are presented for the perturbed infinite square lattice, and a comparison is carried out for those of the perturbed and perfect infinite square network.

Superparamagnetic nanoparticles are very interesting objects having many applications among which MRI contrast agents are one of the more important. In this work the longitudinal relaxation times of Endorem and Lumirem, two colloidal solutions of iron oxide nanoparticles used as contrast agents for magnetic resonance imaging were measured at magnetic field intensities similar to the ones used in MRI. T1 was seen to depend on nanoparticle concentrations as expected but, for the Lumirem, also on the time spend by the sample under the influence of the static magnetic field. The T1 evolution was measured for colloidal solutions both different concentrations and different viscosities. The strange T1 dependence is presented and discussed relating to the nanoparticles superparamagnetic properties. It is shown that one of the possible reasons for the fact is the formation of local field enhanced linear arrays of SPIO.

The reconfiguration time of a holographic beam-shaping device using a liquid crystal spatial light modulator (SLM) has been drastically decreased by five orders of magnitude to reach the microsecond range (~5 µs). The method involves an acousto-optic modulator (AOM) placed in front of the SLM which points the laser beam towards different pre-addressed regions of the liquid crystal plate. Because the addressing signal is not changed, the reconfiguration time is mainly governed by the AOM response time. Moreover, this method allows us to clean up the transient regime by suppressing the bleed effect usually observed in the standard SLM reconfiguration.

We recently setup a high energy, tunable, injection seeded Ti:Sapphire laser source whose implementation was reported in [Rev. Sci. Instrum. 78, 033102 (2007)]. The analysis of the spectral linewidth has demonstrated that the pulses were time Fourier-transform limited. The present paper reports on the modeling of this source with the aim of understanding the energy conversion in the injected as well as in the free run regimes. The experimental lasing threshold, output energy, slope efficiencies, buildup time, and pulse duration are compared to the analytical solution obtained by solving the laser rate equations. The developed model deals with the spatial dependence of the photon and population inversion densities, the physical properties of the Ti:Sa medium, and the unstable resonator (based on a super-Gaussian output coupler). The energy-related as well as the temporal features are discussed. The use of a squared asymmetrical hyperbolic secant function to describe the temporal pulse shapes is justified. The pulse durations exhibit a simple analytical shape when they are plotted versus the output pulse energy. The model is applied to experimental data obtained at different wavelengths by tuning the laser amplifier previously described. It can readily be applied to other pulsed Ti:Sapphire sources.

The use of CR-39, a solid state nuclear track detector, to detect the emission of energetic charged particles during Pd/D co-deposition is demonstrated. The pits observed in the CR-39 are attributed to the Pd/D cathode and are not due to radionuclide contamination in the cell components; nor to the impingement of D2 bubbles on the surface of the CR-39; nor to chemical attack by D2, O2, or Cl2. The features (i.e., optical contrast, shape, and bright spot in the center of the pit) of the pits generated during Pd/D co-deposition are consistent with those observed for pits that are of a nuclear origin.

A transmission type of experiment was set-up to investigate coherent light scattering on suspensions with scattering centers having a wider size distribution. For each sample the contrast, the average intensity and the average speckle size of the far interference field were calculated using an alternative simple algorithm that is presented in detail. The variation of the far field parameters with the scattering centers concentration is presented. A possible application in measuring the scattering centers concentration in the very small values range is suggested and the range is indicated.

An efficient method was proposed to determine the cross sections of charge exchange in ion-molecule collisions. The cross sections for charge exchange were derived by comparing the calculated ion transport parameters with the measured data. The computational procedure was presented by obtaining the cross sections of charge exchange for NO+ and CO+ ions in NO and CO gases, respectively. The present method is usable for providing the accurate cross sections of charge exchange in ion-molecule collisions with the particle modeling of plasma discharges.

In this paper the new approach is proposed to consider a large number of resonantly interacting internal waves in order to investigate the evolution of the energy spectrum in the ocean. The approach is based on a new method for deriving and solving the system of coupled differential equations that govern the evolution of the waves on the interaction time scale. All previous analytical models are based on studying of three resonant internal waves and under hydrostatic approximation. The case of eight resonant waves has been studied experimentally in [J. Fluid Mech. 30, 723 (1967)]. To study the oceanic energy spectrum, only statistical models has been used which are not precise enough to provide estimates of energy exchange in the ocean. The model reported in this paper, provides an illustrative example involving 140 000 resonant internal waves. In this model we don't need to assume the hydrostatic approximation. So our model involves internal waves with frequencies spanning the range of possible frequencies, i.e., between a maximum of the buoyancy frequency N to a minimum of the inertial frequency f. Periodic nature of the spectrum (which has never been reported in previous studies) is investigated. The possible application of this model to investigation of internal waves energy dissipation is discussed.

In this work, we present an algorithm for the space vector pulse width modulation (SVPWM) applied to five-level diode clamped inverter. In this algorithm, the space vector diagram of the five-level inverter is decomposed into six space vector diagrams of three-level inverters. In turn, each of these six space vector diagrams of three-level inverter is decomposed into six space vector diagrams of two-level inverters. This idea allows us to generalize the two-level SVPWM algorithm into the case of five-level inverter.

Acoustic streaming patterns, velocity fields, which is induced by a cylindrical ultrasonic exciter vibrating at 28.4 kHz in an open physical boundaries, is analytically and experimentally investigated using Particle Imaging Velocimetry (PIV). Induced acoustic streaming patterns and velocity fields for the gaps of 18 mm at which the irrotational tangential velocity becomes a maximum, resulting in a substantial increase in the acoustic streaming velocity and pronounced visualization of streaming patterns between the vibrator and quiescent glass plate are presented. The overall air flow patterns at the gaps of 24, 30, 36 mm are similar to the gap of 18 mm but as the gap increases the frequency of occurrence and irregularity of vortices in the gap appear to increase. The symmetric definite steady circular flow with local vortices is observed. The maximum streaming velocity measured stands at 0.16 cm/s with a vibration amplitude of 50 micrometers. Theoretical analysis indicates that the pattern of air flow in the gap is determined by the top and bottom limiting velocities induced by acoustic streaming within the Stokes boundary layer and that the streaming pattern is symmetrical with respect to the center axis of the vibrator by reason of symmetry. The comparison between the experimental data and the theoretical estimation based on Nyborg and Jackson is performed.

In most organs, depending on the scale, the nature of the heart pump, the geometry and topology of the organ, some of the blood vessels tend to exhibit sinuous trajectories. We describe a part of this sinuous behavior, including partial biological and strong physical effects in a global physical framework. We will voluntarily focus on physical and topological effects. This study is performed on the vitelline membrane of the chicken embryo. Crossing angles, sinuosity, and the oscillation amplitude of the vascular system are analyzed. Surprisingly, the equation of river meandering dynamics is found to model the sinuosities in the vascular system, and an extension of this equation to non planar case is able to explain the effect of tissue global curvature on the vascular system. Results of this study could lead to a new understanding of the interplay between biological signaling and physical effects in determining the vascular pattern in different tissues.