MOVPE growth study of BxGa(1−x)N on GaN template substrate

BGaN materials with good structural quality and surface morphology have been successfully grown on GaN template substrates by low pressure metal organic vapour phase epitaxy. TEB and NH3 were used as precursors of boron and nitrogen respectively. All the growths were performed under 100% N₂ process gas. Boron concentration was estimated by HRXD measurements combined with SIMS analysis. Single-crystal layers of BGaN with B content as high as 3.6% have been obtained.     

Mechanical properties of block copolymer vesicle and micelle modified epoxies

Block copolymers with and without reactive functionalities can improve fracture resistance in brittle epoxies even when added in relatively small amounts (<5 wt %). At certain compositions, amphiphilic block copolymers spontaneously self‐assemble into vesicles, spherical micelles, or wormlike micelles in thermoset resins, and these morphologies are retained with the full curing of the resins. The addition of such block copolymers leaves the glass‐transition temperature of these blends relatively unchanged, whereas the fracture resistance increases up to a factor of 3.5 for the vesicle‐modified blends. For epoxies modified with block copolymers self‐assembled into a spherical geometry (vesicles or spherical micelles), the fracture resistance scales with the ratio of the interparticle distance to the average vesicle (or spherical micelle) diameter (D_i/D_p) and increases as this quantity is reduced. Greater adhesion between the vesicle and epoxy resin improves the fracture resistance only at higher values of D_i/D_p, at which the materials are more brittle. Debonding and subsequent matrix plastic deformation are identified as the toughening mechanisms in these blends. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2444–2456, 2003     

Simulation théorique et expérimentale du fonctionnement d’un banc de mesure à structure triaxiale appliquée à la mesure de l’impédance de transfert des câbles multifilaires blindés

We are interested in the present paper in the measure of the transfer impedance and the near-end crosstalk voltages of multi-wire shielded cable by applying the well-known transmission-line theory. Using the impedance and admittance transfer measurement set up, we show that conductors inside the shield play an important role in the evaluation of the internal voltages. We equally show that when the conduction coupling appear, we can not neglect the reaction of the interior wires with regard to the exterior.     

A low-power reduced swing global clocking methodology

In this brief, we investigate the potential of reduced swing clock networks for low-power applications. We designed and laid out a full swing conventional and a reduced swing H-tree clock distribution network in 0.13-/spl mu/m CMOS technology operating at 500 MHz. In the reduced swing clock network, the swing was reduced in the global clock distribution network and was restored to the full swing in the local clock distribution domains. The post-layout simulation results of this research shows that a power saving of 22% under nominal operating condition is feasible.     

A Semidefinite Programming approach for solving Multiobjective Linear Programming

Several algorithms are available in the literature for finding the entire set of Pareto-optimal solutions of Multiobjective Linear Programmes (MOLPs). However, all of them are based on active-set methods (simplex-like approaches). We present a different method, based on a transformation of any MOLP into a unique lifted Semidefinite Program (SDP), the solutions of which encode the entire set of Pareto-optimal extreme point solutions of any MOLP. This SDP problem can be solved, among other algorithms, by interior point methods; thus unlike an active set-method, our method provides a new approach to find the set of Pareto-optimal solutions of MOLP.     

Corrosion Inhibition of Mild Steel in Acidic Solutions Using 1,2,4-Triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidine

The inhibiting action, thermodynamics, and adsorptive properties of 1, 2, 4-triazolo[1, 5-a]pyrimidine (TP) have been investigated for the corrosion of mild steel in 0.5 M H₂SO₄ and 0.5 M H₃PO₄ solutions by means of potentiodynamic, electrochemical impedance spectroscopy techniques and quantum chemical calculations. Results obtained revealed that TP is more effective in 0.5 M H₃PO₄ than in 0.5 M H₂SO₄. Theoretical fitting of different adsorption isotherms such as Langmuir, Flory–Huggins, Temkin, and the kinetic-thermodynamic models were tested. The obtained experimental data fitted all the applied adsorption isotherms except Langmuir. The thermodynamic activation parameters were calculated. The potential of zero charge was also determined using AC measurements to clarify the nature of surface charge of the mild steel in both acidic solutions. Quantum chemical parameters were calculated and explained. The data explained that the inhibition of mild steel in both acidic solutions takes place through physicochemical adsorption mechanism.     

On the Origin of the Large Stokes-Shift of the Emission of CdS Nanoparticles Embedded in a Phosphate Glass Matrix

XRD and TEM characterisation evidenced the formation of well-dispersed CdS nanoparticles inside a phosphate glass matrix. Optical absorption and time-resolved photoluminescence study were carried out on the prepared glass samples. Optical absorption revealed the fast character of the growth of CdS nanoparticles in this medium. Photoluminescence spectra showed only one large band with a maximum at almost 740 nm, which was associated to transitions between energy levels within the bandgap of the CdS nanoparticles. From the steady state and time-resolved measurements, it was suggested that the emission comes mainly from sulfur vacancies inside the nanocrystals and on its surface, which act as deep traps for the photogenerated electrons. The creation of such vacancies was attributed to the loss of sulfur during the glass preparation as evidenced from a chemical analysis using energy dispersive X-ray spectrometry. These traps may be also induced by the fast growth of CdS nanocrystals in this matrix or laser exposure during PL measurements. These CdS-doped glasses with an intense absorption in the UV–Vis region and a large emission band with long lifetime and a large Stokes-shift are adequate for luminescent solar concentrators, photocatalytic applications and solid-state lasers.     

Modeling the spread of Rubella disease using the concept of with local derivative with fractional parameter

Our aim in this work was to examine the model underpinning the spread of the Rubella virus using the novel derivative called beta‐derivative. The study of the equilibrium points together with the analysis of the disease free equilibrium points was presented. Due to the complexity of the modified equation, we introduced a new operator based on the Sumudu transform. The properties of this operator were proposed and proved in detail. We made used of this operator together with the idea of perturbation method to derive a special solution of the extended model. The stability of the method for solving this model was presented. The uniqueness of the special solution was presented, and numerical simulations were done. The graphical representations show that the model depends on both parameters and the fractional order. © 2015 Wiley Periodicals, Inc. Complexity 21: 442–451, 2016