Iteration functions for <Emphasis Type="Italic">p</Emphasis>th roots of complex numbers

A novel way of generating higher-order iteration functions for the computation of pth roots of complex numbers is the main contribution of the present work. The behavior of some of these iteration functions will be analyzed and the conditions on the starting values that guarantee the convergence will be stated. The illustration of the basins of attractions of the pth roots will be carried out by some computer generated plots. In order to compare the performance of the iterations some numerical examples will be considered.     

Diameter of P.A. random graphs with edge‐step functions

In this work we prove general bounds for the diameter of random graphs generated by a preferential attachment model whose parameter is a function f:N→[0,1] that drives the asymptotic proportion between the numbers of vertices and edges. These results are sharp when f is a regularly varying function at infinity with strictly negative index of regular variation ?γ. For this particular class, we prove a characterization for the diameter that depends only on ?γ. More specifically, we prove that the diameter of such graphs is of order 1/γ with high probability, although its vertex set order goes to infinity polynomially. Sharp results for the diameter for a wide class of slowly varying functions are also obtained.     

Synthesis and Characterization of BaFe2As2 Single Crystals Grown by In-flux Technique

We report a detailed characterization of BaFe₂As₂ single crystals grown by a metallic In-flux technique, an alternative to well-established growth routes using FeAs self- or Sn-flux. Electrical resistivity, magnetic susceptibility, nuclear magnetic resonance, and energy dispersive spectroscopy measurements showed no evidence of flux incorporation. More importantly, our results demonstrate that BaFe₂As₂ single crystals grown by In-flux have extremely high quality. To explore the efficiency of the In-flux growth method, we have also prepared nearly optimally doped superconducting samples of Ba(Fe_{1 ?x} M _x )₂As₂ (M = Co, Cu, Ni, and Ru). Among other interesting features, this alternative chemical substitution method has led to enhancement of the maximum T _c for most dopings.     

Application of advanced oxidation processes for removing salicylic acid from synthetic wastewaters

<正>In this study,advanced oxidation processes(AOPs) such as anodic oxidation(AO),UV/H_2O_2 and Fenton processes(FP) were investigated for the degradation of salicylic acid(SA) in lab-scale experiments.Boron-doped diamond(BDD) film electrodes using Ta as substrates were employed for AO of SA.In the case of FP and UV/H_2O_2,most favorable experimental conditions were determined for each process and these were used for comparing with AO process.The study showed that the FP was the most effective process under acidic conditions,leading to the highest rate of SA degradation in a very short time interval.However,the results showed that Ta/BDD films had high electrocatalytic activity for complete degradation of SA;even if it employs more time for complete elimination of the SA respect to FP.Additionally,AO led to a sixfold acceleration of the oxidation rate compared with the UV/H_2O_2 process.Finally a rough comparison of the specific energy consumption shows that AO process reduced the energy consumption by at least 90%compared with the UV/H_2O_2 process.     

The enthalpies of dissociation of the N?O bonds in two quinoxaline derivatives

The present work reports the first experimental thermochemical study of mono‐N‐oxides derived from quinoxaline, namely, 3‐methoxycarbonyl‐2‐methyl‐quinoxaline N‐oxide and 3‐ethoxycarbonyl‐2‐methyl‐quinoxaline N‐oxide. The values of the enthalpies of formation, in the condensed state, and of the enthalpies of sublimation, derived from static bomb calorimetry and Calvet microcalorimetry measurements, respectively, are combined to derive the standard molar enthalpies of formation in the gaseous phase for these two compounds. From the latter values, the first and second N? O bond dissociation enthalpies for the corresponding di‐N‐oxides have been obtained. The gas‐phase experimental results are also compared with calculated data obtained with a density functional theory approach. Copyright © 2008 John Wiley & Sons, Ltd.     

3D–2D–0D Stepwise Deconstruction of a Water Framework Templated by a Nanoporous Organic–Inorganic Hybrid Host

The supramolecular salt [H₂pip]₃[Ge(hedp)₂]?14 H₂O ( 1 ) [H₂pip²⁺=piperazine cation C₄H₁₂N₂²⁺; hedp^5?=deprotonated form of etidronic acid, C₂H₃P₂O₇^5?) is reported. This consists of an organic–inorganic hybrid hydrogen‐bonded nanoporous framework, the internal surface of which acts as a template for the three‐dimensional (3D) clustering of water molecules. The structure and molecular dynamics of this material are characterised by single‐crystal X‐ray diffraction, thermogravimetric analysis, Raman (H/D isotopic substitution) spectroscopy, and ²H solid‐state (wide‐line and MAS) NMR spectroscopy. Material 1 is shown to be unusual because 1) few nanoporous materials exhibit a well‐organised 3D framework of water molecules, 2) it provides a unique opportunity to follow experimentally and to rationalise the deconstruction of a 3D water framework and 3) despite the fact that the hybrid framework is a supramolecular salt, the structure does not collapse after dehydration and the final material is crystalline.     

Speckle decorrelation influence on measurements quality in vortex metrology

We study speckle decorrelation effects in connection with conventional vortex metrology techniques. Our proposal is based on processing speckled images recorded by using two different experimental set-ups. In both schemes two laterally displaced patterns are generated: one scheme allows for obtaining undecorrelated speckle distributions and the other for decorrelated ones. Vortex networks associated with speckle patterns are analyzed by employing the usual tools developed for vortex metrology. For each recorded image, a 2D pseudo-phase map is generated on the basis of the Reisz transform. Then the vortices are located, and parameterized in terms of their topological charge, eccentricity, vorticity and angles between the zero crossing lines from the real and the imaginary parts of the analytical signal. After tracking the homologous vortices onto the maps, the histograms corresponding to the coordinate displacements are analyzed. We show that histograms interpretation is prone to failure due to its high sensitivity to decorrelation. Experimental evidences are presented to support the restrictions imposed by decorrelation of actual speckles due to uniform in-plane displacements.     

Assembly of Nano-Biocatalyst for the Tandem Hydrolysis and Reduction of p-Nitrophenol Esters

Hybrid nano-biomaterials are exploited in the design and performance of chemo-enzymatic cascades. In this study, lipase is immobilized from Candida antarctica fraction B (CALB) and gold nanoparticles (Au NPs) on magnetic particles coated with silica (MNP@SiO₂) to stepwise hydrolyze and reduce p-nitrophenyl esters in tandem reaction. The assembly of the two catalysts at the interface of the MNP@SiO₂ particles and the temporal control of the reaction turns out to be the most determinant parameters for the cascade kinetics. When both CALB and Au NPs are co-immobilized at the MNP@SiO₂ particle, the tandem reactions take place significantly faster than when both catalysts are physically segregated by their immobilization on different MNP@SiO₂ particles. Herein, it is demonstrated that the co-immobilization of biocatalysts and nanocatalysts in solid materials creates hybrid interfaces that accelerated chemo-enzymatic tandem reactions.