Effective Mass of Radion via GW Mechanism with a Non-Minimally Coupled Bulk Scalar Field

In the Randall-Sundrum braneworld scenario via the Goldberger-Wise mechanism, the effective mass of 4D radion, where the bulk scalar field is coupled to 5D gravity, has been investigated in two different case of the self-coupling constants, infinite and finite cases. It is shown that in the finite case, the modulus parameter should be greater than the finite coupling constants.     

Copper-based metal–organic framework decorated by CuO hair-like nanostructures: Electrocatalyst for oxygen evolution reaction

We report a Cu-based metal–organic framework (MOF) decorated by CuO nanostructures as an efficient catalyst for the oxygen evolution reaction (OER). MIL-53(Cu) was synthesized by a hydrothermal approach using 1,4-bezenedicarboxylic acid as organic precursor and further annealed at 300°C to form CuO nanostructures on its surface. The produced electrocatalyst, CuO@MIL-53(Cu), was characterized using various techniques. Under alkaline conditions, the developed electrocatalyst exhibited an overpotential of 801 and 336 mV versus RHE at 10 and 1 mA cm⁻², respectively. The reproducibility of the catalytic performance was validated using several electrodes. It was confirmed that the CuO hair-like nanostructures grown on MIL-53(Cu) using thermal treatment exhibit high OER activity, good kinetics and durability. CuO@MIL-53(Cu) is an economic noble-metal-free OER electrocatalyst. It has potential for application as anode material for sustainable energy technologies like batteries, fuel cells and water electrolysis.     

A comparative study on the catalytic performance of heme and non‐heme catalysts: Metal porphyrins versus metal Schiff bases

Catalytic activity and oxidative stability of a series of iron and manganese porphyrins with 2‐chlorophenyl, phenyl and 4‐methoxyphenyl at the meso positions and metallosalens (Mn‐ and Fe‐salens) including N,N′‐bis(salicylidene)ethylenediamine, N,N′‐bis(5‐ chlorosalicylidene)ethylenediamine and N,N′‐bis(2,4‐dihydroxysalicylidene)ethylenediamine for the oxidation of olefins with tetra‐n‐butylammonium periodate (TBAP) and tetra‐n‐butyl‐ammonium Oxone (TBAO) have been investigated and compared. Although the metalloporphyrins showed an increased catalytic activity relative to the Schiff base complexes, the former provided no significant catalytic advantage over the latter. Also, a comparable or slightly higher oxidative stability was observed for the Schiff base complexes under the reaction conditions. Furthermore, in spite of large difference between the oxidizing ability of TBAO and TBAP, similar patterns were observed for the order of catalytic activity and oxidative stability of the used heme and non‐heme catalysts. The introduction of a methyl group at the ɑ position of styrene led to an increase in its reactivity, indicating the dominance of electronic effects over the steric ones in these catalytic systems.     

Neutral Minima in Three-Higgs Doublet Models

We study the structure of the most general three Higgs doublet model. By imposing discrete and continuous symmetry on the scalar fields the number of parameters of the model is drastically reduced. It is possible to describe the model in terms of nine invariants. We use the formalism to study an specific model with eight real parameters. We discuss the structure of neutral minima for this model.     

Polarization maintaining optical fiber multi-intruder sensor

In this paper, an optical fiber multi-intruder sensor based on polarization maintaining optical fiber (PMF), without any interferometric fiber loop, is introduced. To map the local coordinates of intruders on the beating spectrum of the output modes, radiation from a ramp frequency modulated laser is injected at the input of PMF optical fiber sensor. It is shown that the local coordinates and some characteristics of intruders can be obtained by the measurement of the frequencies and amplitudes of the output mode beating spectrum. Generally the number of beating frequencies is more than the number of intruders. Among the beating frequencies, a group with maximum signal to noise ratio is chosen. The short Fourier denoising method is employed to increase the sensor resolution. Because the output signal is the superposition of finite numbers of discrete frequencies this method is a powerful tool for denoising even for negative signal to noise ratio.     

Fermion Localization on the <Emphasis Type="Italic">orbifold</Emphasis><Emphasis Type="Italic">S</Emphasis><Subscript>1</Subscript>/<Emphasis Type="Italic">Z</Emphasis><Subscript>2</Subscript>

The hierarchical structure of fermion masses of the Standard Model is explained in split fermion models by localizing the fermions at different points in an extra dimension. We consider split fermion models with two bulk scalars compactified on an orbifold. In the static case we find analytical expression for the localizer. We also address the issue of stability of the localizer. We also find exact solutions for the fermion zero modes. We explore the parameter space of the model. We find ample opportunity for construction of phenomenologically viable theories exist.     

Exothermic Transition to a Future Susy Universe

The Higgs sector of the MSSM may be extended to solve the μ problem by the addition of a gauge singlet scalar field. We consider an extended Higgs model. For simplicity we consider the case where all the fields in the scalar sector are real. We analyze the vacuum structure of the model. We address the question of an exothermic phase transition from a broken susy phase with electroweak symmetry breaking (our current universe) to an exact susy phase with electroweak symmetry breaking (future susy universe).     

The effect of normal electric field on the evolution of immiscible Rayleigh-Taylor instability

Manipulation of the Rayleigh-Taylor instability using an external electric field has been the subject of many studies. However, most of these studies are focused on early stages of the evolution. In this work, the long-term evolution of the instability is investigated, focusing on the forces acting on the interface between the two fluids. To this end, numerical simulations are carried out at various electric permittivity and conductivity ratios as well as electric field intensities using Smoothed Particle Hydrodynamics method. The electric field is applied in parallel to gravity to maintain unstable evolution. The results show that increasing top-to-bottom permittivity ratio increases the rising velocity of the bubble while hindering the spike descent. The opposite trend is observed for increasing top-to-bottom conductivity ratio. These effects are amplified at larger electric field intensities, resulting in narrower structures as the response to the excitation is non-uniform along the interface.     

Effect of Stacking Sequence on Low-Velocity Impact Behavior of Metal Laminates

In this paper, the low-velocity impact behavior of metal laminates was studied experimentally and numerically. Metal laminates with different number of metal layers and different stacking sequences were investigated by examining the contact force, the contact duration, the dissipated energy and the transverse displacement as the main low-velocity impact responses. It was found that from stacking sequence perspective, the low-velocity impact responses of metal laminates were mainly affected by the volume fraction of metal layers, the material characteristics of the first and last metal layers and the number of metal layers. Increasing the number of metal layers in a constant thickness of metal laminates decreased the contact force and increased the contact duration and transverse displacement. The use of higher volume fraction of a metal material in a metal laminate caused the metal laminate to inherit more of the impact characteristics of that material. The results of this research can assist engineers to design metallic structures with desired low-velocity impact behaviors.     

Phase structure of the generalized two-dimensional Yang-Mills theory on sphere

We find a general expression for the free energy of generalized two-dimensional (2D) Yang-Mills theory in the strong () region for large N. We also show that in this region, the density function of Young tableau of these models is a three-cut problem. In the specific model, we show that the theory has a third order phase transition, like the (YM) and models. We note problems for cases where , and at the end, examine the phase structure of the model for the region. Received: 30 September 1998 / Revised version: 13 December 1998 / Published online: 15 April 1999