Synthesis,characterization, catalase functions and DNA cleavage studies of new homo and heteronuclear Schiff base copper(II) complexes

A new tetradentate diimine–dioxime ligand containing a donor set of N₄, and its homo-, heterodinuclear and homotrinuclear copper(II) complexes were prepared and characterized on the basis of their elemental analysis, FT-IR, ¹H and ¹³C NMR spectra, molar conductivity and magnetic moment measurements. The extraction ability of N,N′′-bis[1-biphenyl-2-hydroxyimino-1-ethylidene]-diethylenetriamine was also evaluated in chloroform by using several transition metal picrates such as Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pb(II), Cd(II) and Hg(II). It has been seen that the ligand shows strong binding ability toward the copper(II) ion. Moreover, the catalytic activities of the complexes for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The synthesized complexes display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity. The interaction between these complexes and DNA has also been investigated by agarose gel electrophoresis. We found that the homo- and heterodinuclear copper complexes can cleave supercoiled pBR322 DNA to nicked and linear forms. The dinuclear complexes including phenanthroline (2–4), with H₂O₂ as a co-oxidant, exhibited the strongest cleaving activity.     

Optimality conditions for the control of a double-membrane complex system by a modal decomposition technique

The optimal of damping out the oscillations of an elastically rectangular double-membrane system by means of point-wise actuators is solved analytically. The membrane is clamped along the boundaries. The motion of the system is initiated by given initial displacement and velocity conditions. The basic control problem is to minimize the deflection and the velocity of displacements at a specified time with the minimum expenditure of actuation energy. A quadratic performance functional is chosen as the cost functional which comprises the functionals of the deflection, velocity and the point-wise actuators. Necessary and sufficient conditions of optimality are investigated. The necessary conditions of optimality are obtained from a variational approach and formulated in the form of degenerate integrals which lead to explicit optimal control laws for the actuators. Numerical results are given for various problem parameters and the efficiency of the control mechanism is investigated.     

Nonlinear degenerate parabolic equations for Baouendi–Grushin operators

In this paper, we shall investigate the nonexistence of positive solutions for the following nonlinear parabolic partial differential equations: and Here, Ω is a Carnot–Carathéodory metric ball in R ^N and V ∈ L ¹_loc(Ω). The critical exponents m * and p * are found, and the nonexistence results are proved for m * ≤ m < 1 and p * ≤ p < 2. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization, crystal structure and chemical behavior of [1,1-bis(diphenylphosphinomethyl)ethene]ruthenium(II) complex toward primary alkylamine addition

Reaction of the ruthenium phosphine complex [RuCl₂(PPh₃)₃] 1 with an unsaturated functionalized diphosphine ligand, namely 1,1-bis(diphenyl-phosphinomethyl)ethene, H₂C=C(CH₂PPh₂)₂, (dppme) gave trans-Cl₂Ru(dppme)₂ 2. Complex 2 served as a precursor for the synthesis of trans-Cl₂Ru(dppme)(alkylamine)₂ complexes 3–5 by reaction with RNH₂. All these complexes were characterized by spectroscopic techniques and by elemental analysis. The solid-state structure of complex 2 was determined by X-ray crystallography.     

Zirkonium, Hafnium, Thorium, Germanium

Ohne Zusammenfassung     

Bipolar tri-state resistive switching characteristics in Ti/CeO_x/Pt memory device

Highly repeatable multilevel bipolar resistive switching in Ti/Ce Ox/Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of Ce O2 films reveal the formation of weak polycrystalline structure. The observed good memory performance, including stable cycling endurance and long data retention times（〉10^4s） with an acceptable resistance ratio（～10^2）, enables the device for its applications in future non-volatile resistive random access memories（RRAMs）. Based on the unique distribution characteristics of oxygen vacancies in Ce Ox films, the possible mechanism of multilevel resistive switching in Ce Ox RRAM devices has been discussed. The conduction mechanism in low resistance state is found to be Ohmic due to conductive filamentary paths, while that in the high resistance state was identified as Ohmic for low applied voltages and a space-charge-limited conduction dominated by Schottky emission at high applied voltages.     

Heat transfer of dilute viscoelastic solutions in helical exchangers

The study examined heat transfer of two dilute viscoelastic solutions in helical exchangers of circular cross-section. Ten helical coil heat exchangers with diameter ratios ranging from 4 to 50 were constructed. Results showed doubling the concentrations of polymer increased heat transfer performance by 12 %. The results were expressed in forms of some existing equations and were found to be in fair agreement to previous results.     

Effect of localized faults on chaotic vibration of rolling element bearings

This paper investigates the effect of localized faults on the chaotic vibration of rolling element bearings. The presence of chaotic behavior is demonstrated using experimental vibration data. A nonlinear mathematical model is developed that captures bearing dynamics. The numerical simulations of the model agree with the experimental evidence and provide insight into the bearings chaotic response in a wide range of rotational speeds. The bearing chaotic behavior is quantified using the Lyapunov exponent and correlation dimension. It is further shown that these measures can be exploited in detecting bearing failure.