On Variational Based Scale-Bridging of Inelastic Composites

The paper discusses formulations for the theoretical and numerical analysis of inelastic composites with scale separation. The basic underlying structure is a canonical variational setting in the fully nonlinear range based on incremental energy minimization. We focus on formulations of strain–driven homogenization for representative composite aggregates with emphasis on the development of canonical families of algorithms based on Lagrange and penalty functionals to cover alternative boundary constraints of (i.) linear deformations, (ii.) periodic deformations and (iii.) uniform tractions. As a key result, we present a compact matrix formulation for homogenization covering introduced alternative boundary constraints. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparison of wide and compact fourth‐order formulations of the Navier–Stokes equations

In this study the numerical performances of wide and compact fourth‐order formulation of the steady 2D incompressible Navier–Stokes equations will be investigated and compared with each other. The benchmark driven cavity flow problem will be solved using both wide and compact fourth‐order formulations and the numerical performances of both formulations will be presented and also the advantages and disadvantages of both formulations will be discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

3D Motions of Iron in Six‐Coordinate {FeNO}7 Hemes by Nuclear Resonance Vibration Spectroscopy

The vibrational spectrum of a six‐coordinate nitrosyl iron porphyrinate, monoclinic [Fe(TpFPP)(1‐MeIm)(NO)] (TpFPP=tetra‐para‐fluorophenylporphyrin; 1‐MeIm=1‐methylimidazole), has been studied by oriented single‐crystal nuclear resonance vibrational spectroscopy (NRVS). The crystal was oriented to give spectra perpendicular to the porphyrin plane and two in‐plane spectra perpendicular or parallel to the projection of the FeNO plane. These enable assignment of the FeNO bending and stretching modes. The measurements reveal that the two in‐plane spectra have substantial differences that result from the strongly bonded axial NO ligand. The direction of the in‐plane iron motion is found to be largely parallel and perpendicular to the projection of the bent FeNO on the porphyrin plane. The out‐of‐plane Fe‐N‐O stretching and bending modes are strongly mixed with each other, as well as with porphyrin ligand modes. The stretch is mixed with v₅₀ as was also observed for dioxygen complexes. The frequency of the assigned stretching mode of eight Fe‐X‐O (X=N, C, and O) complexes is correlated with the Fe?XO bond lengths. The nature of highest frequency band at ≈560 cm^?1 has also been examined in two additional new derivatives. Previously assigned as the Fe?NO stretch (by resonance Raman), it is better described as the bend, as the motion of the central nitrogen atom of the FeNO group is very large. There is significant mixing of this mode. The results emphasize the importance of mode mixing; the extent of mixing must be related to the peripheral phenyl substituents.     

A remark on the paper “Laterally closed lattice homomorphisms”

A new and simple proof of the main result of the paper “Laterally closed lattice homomorphisms” by Toumi and Toumi (J Math Anal Appl 324:1178–1194, 2006) is given following the paper “Extension of Riesz homomorphisms, I” by Buskes (J Aust Math Soc Ser A 39(1):107–120, 1985).     

Influences of Co-60 gamma-ray irradiation on electrical characteristics of Al2O3 MOS capacitors

Effects of gamma-ray irradiation on the electrical characteristics of Al₂O₃ MOS capacitors such as barrier height, acceptor concentration, series resistance and interface state parameters have been studied by analyzing capacitance–voltage (C–V) and conductance–voltage (G/ω–V) measurements. The fabricated MOS capacitors were irradiated with gamma-rays at doses up to five grays. C–V and G/ω–V measurements were recorded prior to and after irradiation at high frequency. The results show that the measured capacitance and conductance values decreased with increasing in irradiation dose and C–V and G/ω curves has been shifted toward the negative voltages. Moreover, the series resistance (R _s) and density of interface states increased with increasing in irradiation dose and density of interface states (D _it) were calculated as order of 10¹² eV^?1cm^?2 prior to and after irradiation. Due to presence and variations in the R _s values, the corrected and the measured C–V and G/ω–V exhibited different behaviors. Therefore other electrical characteristics were assessed from corrected C _c characteristics. It was observed that acceptor concentration decreased with increasing in barrier height of device due to changes in interface states and diffusion potential.     

Structural and electronic characterization of non-heme Fe(II)-nitrosyls as biomimetic models of the Fe(B) center of bacterial nitric oxide reductase

The detoxification of nitric oxide (NO) by bacterial NO reductase (NorBC) has gained much attention as this reaction provides a paradigm as to how NO can be detoxified anaerobically in cells. However, a clear mechanistic picture of how the heme/non-heme active site of NorBC activates NO is lacking, mostly as a result of insufficient knowledge about the properties of the non-heme iron(II)-NO adduct. Here we report the first biomimetic model complexes for this species that closely resemble the coordination environment found in the protein, using the ligands BMPA-Pr and TPA. The systematic investigation of these compounds allowed us to gain key insight into the electronic structure and geometric properties of high-spin non-heme iron(II)-NO adducts. In particular, we show how small changes in the ligand environment of iron could be used by NorBC to greatly modulate the properties, and hence, the reactivity of this species.     

The surface oxidation behavior of Ni–45.16%Ti shape memory alloys at different temperatures

The isothermal oxidation behavior of Ni–45.16%Ti (composition in atomic percent) alloy was investigated by thermogravimetric analysis, and differential scanning calorimeter (DSC) methods. It was found that Ni-rich NiTi alloy exhibits a different oxidation behavior at temperatures above 400 °C in oxygen atmosphere. The alloy was exposed to oxygen atmosphere isothermally, i.e., between 400 and 800 °C, for 1 h. A gravimetric method was used to determine the oxidation kinetics and it was seen that the oxidation constant increases significantly with isothermal temperature. The activation energy of oxidation reaction for NiTi alloy was determined to be 65.47 kJ mol^?1. According to DSC measurements, the transformation temperature of alloy (M _s, M _f, A _s and A _f) was increased and also R phase disappeared above 500 °C. The formal oxides were determined by means of SEM–EDX measurements and obtained oxides are TiO and TiO₂ oxides.     

Invariant subspaces for positive operators on locally convex solid Riesz spaces

We prove that an x₀-quasinilpotent semigroup S of continuous positive linear operators on a locally convex solid Riesz space X has a common invariant subspace. Using this, a result which implies the main theorem of Abramovich, Aliprantis and Burkinshaw [J. Funct. Anal. 115 (1993) 418424] is also given.     

Generalized Alexandroff Duplicates and CD 0(K) spaces

We define and investigateCD _Σ,Γ(K, E)-type spaces, which generalizeCD ₀-type Banach lattices introduced in [1]. We state that the space CD _Σ,Γ(K, E) can be represented as the space of E-valued continuous functions on the generalized Alexandroff Duplicate of K. As a corollary we obtain the main result of [6, 8].