Analysis of a wide radiating slot in the ground plane of amicrostrip line

An analysis of a wide rectangular radiating slot excited by a microstrip line is described. Coupled integral equations are formulated to find the electric current distribution on the feed line and the electric field in the aperture. The solution is based on the method of moments and using the space domain Sommerfeld-type Green's function. The information about the input impedance or reflection coefficient is extracted from the electric current distribution on the microstrip line utilizing the matrix pencil technique. The theoretical analysis is described and data are presented and compared with other theoretical and experimental results     

EPR, X-ray, and magnetization studies of metastable alloys Ti2Fe, Al40Cu10Mn25Ge25 and Al65Cu20Fe15 as prepared by mechanical alloying

Mechanical alloying (MA) technique has been used to synthesize metastable alloys with nominal compositions Ti₂Fe (MA for 1, 5, and 26 h), Al₆₅Cu₂₀Fe₁₅ (MA for 26 and 34 h) and Al₄₀Cu₁₀Mn₂₅Ge₂₅ (MA for 42 h). These have been studied by EPR, X-ray diffraction, differential thermal analysis (Ti₂Fe only), and magnetization (Ti₂Fe only) techniques. X-ray diffraction provided information on transformation to metastable phases, while the EPR spectra gave insight into inequivalent paramagnetic transition metal sites in the alloys and the temperature variation of magnetic ordering of the samples. Magnetization data on Ti₂Fe system has been interpreted in terms of phase separations within the amorphous phase. It is concluded that MA process significantly influences the magnetic properties of the samples, wherein the duration of MA process plays an important role. The EPR and magnetization data indicate that the disorder of paramagnetic ions within the samples increases with increasing temperature.     

Space domain approach for the analysis of printed circuits

A numerical approach to the solution of printed circuit structures of arbitrary shapes, embedded in a single or multilayer dielectric medium is presented. The electromagnetic fields are described in terms of the classical Sommerfeld integrals. The method of moments has been used to solve the derived integral equations for the surface electric and magnetic currents flowing on the conductors and/or the electric field distribution across the apertures. The matrix pencil technique is employed to decompose the current or the voltage waves along the line into their components like the fundamental modes, higher order modes, etc. The finite structures including discontinuities like bends, T junctions, crossovers, etc. are solved for their scattering parameters utilizing this method. The main advantage of this method is the generality which allows a large variety of problems to be covered     

Collaboration of Ni,polyoxometalates and layered double hydroxides: synthesis,characterization, electrochemical and mechanism investigations as nano-catalyst in the Heck coupling reaction

Nickel (Ni) nanoparticles were immobilized on the surface of magnetic MgAl layered double hydroxide intercalated 10-molybdo-2-vanadophosphate (Fe–MgAl/Mo₁₀V₂–Ni) for the first time. The presence of Ni nanoparticles onthe high-surface area Fe–MgAl LDH structure in the presence of Mo₁₀V₂ makes this catalyst an ideal option in terms of efficiency and selectivity for Heck coupling reaction. Synergic effects of Mo₁₀V₂ and Ni were investigated by an electrochemical technique. Increasing of the ECSA of the catalyst compared to Fe–Mg–Al–Ni leads to enhancement of the catalytic activity and proves the synergic effect. A new catalytic mechanism was introduced for this kind of reaction. The resulting structure and its catalytic behavior were characterized by FT-IR, XRD, ICP-AES, TEM, SEM, EDX, EBSD, XPS, BET, VSM, CV, LSV and zeta potential analyses. More importantly, Fe–MgAl/Mo₁₀V₂–Ni can easily be separated from the reaction mixture using an external magnet and reused for at least four successive runs without any substantial reduction in its catalytic activity.     

New strategy by a two-component heterogeneous catalytic system composed of Pd–PVP–Fe and heteropoly acid as co-catalyst for Suzuki coupling reaction

Research on Chemical Intermediates - We have developed a simple and efficient catalytic protocol composed of hollow palladium-poly(N-vinylpyrrolidone)-nano zero valent iron and H5PMo10V2O40...     

Different products in the reaction of the alcohols with cyclic and acyclic 1,3-dicarbonyl compounds:K5CoW12O40 as an electron transfer nano catalyst

K₅CoW₁₂O₄₀ was used as a highly effective catalyst for the benzylation of 1,3-dicarbonyl compounds.β-Keto enol ethers were obtained when cyclic 1,3-dicarbonyl compounds used in this conditions instead of linear ones.The present methodology offers a practical,simple,mild,environmentally friendly,and time-saving method for etherification.Very low loading of catalyst,ease of workup,ease of handling,and reusability of catalyst are other advantages of this catalyst.     

Incorporation of palladium nanoparticles and 10-molybdovanado phosphoric acid in FeCo layered double hydroxide structure: electrochemical and catalytic investigation for Mizoroki–Heck coupling reactions

Palladium (Pd) has been immobilized on FeCo layered double hydroxide (LDH) intercalated 10-molybdovanado phosphate (FeCo/Mo₁₀V₂-Pd) for the first time. The structure was characterized using various characterization techniques. The electrocatalytic behavior of FeCo/Mo₁₀V₂-Pd was investigated using cyclic voltammetry and linear sweep voltammetry techniques. The presence of Mo₁₀V₂ enhanced the catalytic activity of FeCo-Pd in the Heck coupling reaction. Also, the collaboration of Pd and Mo₁₀V₂ with LDH as a mesoporous support was studied. These reusable solid catalysts exhibited excellent activity, and the methodology is applicable to diverse substrates providing good to excellent yields of the desired products. This method has advantages of high yields, low reaction times, elimination of ligand and base, heterogeneous catalysts and simple methodology. It is notable that FeCo/Mo₁₀V₂-Pd can easily separate from the reaction mixture using an external magnet and reused for at least four successive runs without any considerable decrease in its catalytic activity.

     

Ultra-Low-Voltage Schottky-Barrier Field-Enhanced Electron Emission From Gold Nanowires Electrochemically Grown in Modified Porous Alumina Templates

Superior field emission (FE) action has been observed from a tailored array of gold nanowires (AuNWs) grown in porous anodic alumina (PAA) templates. The turn-on voltage was found to be 0.2 V, which is far less than the values reported earlier for diamond-coated cathodes and carbon nanotubes (CNTs). Furthermore, the FE current was unaffected by the ambient gas pressure. Such a low-voltage FE is attributed here to the formation of a Schottky barrier at the interface of gold and amorphous alumina scales that remain on the AuNWs.     

Dynamic analysis of a microstrip line over a perforated groundplane

A full wave analysis is presented to compute the characteristic impedance and propagation constant of a microstrip line over a perforated ground plane. The perforations in the ground plane are modeled by equivalent magnetic currents. The method of moments is applied to solve the coupled integral equations for the unknown electric current on the microstrip line and the unknown magnetic currents in the apertures. The fields are formulated using the space domain Sommerfeld type Green's functions. The matrix pencil technique is used to obtain the amplitude and the propagation constant of the fundamental modes for both current and the voltage on the microstrip line. Typical numerical results are given