Study of solid-solution hardening in binary aluminium-based alloys

Solid-solution formation in binary aluminium-based alloys is due essentially to the combined effects of the size and valence of solvent and solute atoms, as expected by the four Hume-Rothery rules. The lattice parameter of aluminium in the solid solution of the sputtered Al?Fe films is [Al-a (Å)=4.052?6.6×10^?3Y]. The increasing and decreasing evolution of the lattice parameter of copper [Cu-a (Å)=3.612+1.8×10^?3Z] and aluminium [Al-a (Å)=4.048?1.6×10^?3X] in the sputtered Al-1.8 to 92.5 at. % Cu films is a result of the difference in size between the aluminium and copper atoms. The low solubility of copper in aluminium (<1.8 at % Cu) is due to the valences of solvent and solute atoms in contrast with other sputtered films prepared under similar conditions, such as Al?Mg (20 at. % Mg), Al?Ti (27 at. % Ti), Al?Cr (5at. % Cr) and Al?Fe (5.5 at. % Fe) where the solubility is due to the difference in size.     

Microstructure dependence of yielding and fracture in Cd-Zn alloys

The coefficient of logarithmic work-hardening, the yield stress and the fracture stress of Cd-2 wt. %Zn alloy of different grain diameters and of Cd-17·4 wt. %Zn alloy decrease with increasing working temperature. Two relaxation temperature regions have been found, the low-temperature region of relaxation (below 483 K) and the high-temperature region (above 483 K). The fracture surface energy for Cd-2 wt. % Zn alloy has been calculated and found to be 1·2 J/m² at the two temperature regions of relaxation. X-ray investigations show that the residual internal strains in the deformed samples increase with increasing working temperature and exhibit a peak value at 483 K.     

Spectrometric study of solute–solvent interactions for the solvolysis of chloropentaamine cobalt(III) complex in binary aqueous mixtures

Kinetic studies of solvent structure effects and solute–solvent interactions on the solvolysis of [Co(NH₃)₅Cl]²⁺ complex ion have been investigated spectrophotometrically in binary aqueous mixtures. Three cosolvents were used (acetonitrile, dimethylsulfoxide, and urea) over a wide range of temperatures. Nonlinear plots were found for log(rate constant) against the reciprocal of the relative permitivity of the medium. The enthalpy and entropy of activation (ΔH^# and ΔS^#) exhibited extrema in the same composition region where the physical properties indicate sharp changes in the structure of the solvent, confirming that the solvent structure is an important factor in determining the solvolytic reactivity. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 416–422, 2008     

Complex dynamical behavior in a new chemical oscillator: The chlorite–thiourea reaction in a CSTR

The reaction between chlorite ion and thiourea has been studied both in a closed (batch) system and in a flow reactor (CSTR). The principal stoichiometry is given by In batch, the reaction displays an induction period, whose length is proportional to [CS(NH₂)₂]/[ClO] [H⁺], followed by the rapid buildup and disappearance of a ClO₂ intermediate. At [ClO]/[CS(NH₂)₂] ratios between 2.5 and 3.5, a second peak in the ClO₂ absorbance is observed. In the CSTR, this iodine-free system displays simple and complex periodic oscillation, bistability, aperiodic oscillation, and birhythmicity.     

Ion conductive characteristics of cross-linked network polysiloxane-based solid polymer electrolytes

A series of cross-linked network polysiloxanes containing oligoethylene oxide units, (OCH₂CH₂)_n, as internal free chains have been synthesized by performing hydrosilylation of partially PEO-substituted polysiloxane precursor with , ω-diallyl terminated poly(ethylene glycol). The polymer electrolytes were formed by complexing with LiN(CF₃SO₂)₂ electrolyte salt and exhibited superior conductive property. The σ_RT of the network polymer electrolytes is in the range of 2.50×10⁻⁵ to 1.62×10⁻⁴ S/cm and depends on the cross-linking density (in terms of Si–H amount of the siloxane precursor), repeating unit number of internal oligoethylene oxide and chain length of the cross-linker. The significant enhancement of the conductivity was observed when low molecular weight dimethyl poly(ethylene glycol) was added as plasticizer. The temperature dependence of the ionic conductivity was also studied, following the Vogel–Tamman–Fulcher (VTF) equation.     

Development of a criterion for road surface roughness based on power spectral density function

This study has demonstrated that the non-contact acoustical transducer is a reasonable sensor for reflecting the road roughness profile, and the procedure is much faster in detecting the road surface roughness as compared to other measurement devices. Thus, it is a very promising sensor with regard to road roughness measurement. Furthermore, the ISO may be employed to classify the road grade. However, the assumed linearity in the PSD on a log-log graphical representation may not be true in reality, especially in the lower frequency band. Therefore, a new approach to classify road surface roughness is to be developed.     

Sur les algèbres absolument valuées qui vérifient l'identité (x, x, x) = 0

Let A denote a prehilbert absolute valued real algebra such that (x, x, x) = 0 for all x ε A; for this algebra we obtain the same results we have previously obtained for the flexible absolute valued algebra. Our main theorem is: A has a finite dimension 1, 2, 4 or 8, and is isotopic to or C. One of the results concerning the isomorphism between A and , C^*, or C shows that if for every two idempotents e₁ and e₂ in , then A is isomorphic to , C^*, or C. The example of infinite dimensional Hilbert absolute valued algebra given by Urbanik and Wright indicates that the assumption, (x, x, x) = 0 for all x ε A, is essential.     

Photofragmentation of H2S in the first continuum

The dynamics of the photofragmentation of H₂S in the first continuum has been investigated at laser wavelengths 193, 222 and 248 nm. The HS fragments are produced mainly in υ = 0, as expected, but a non-negligible part of the HS radicals produced are vibrationally excited. The distribution of the vibrationally excited radicals peaks at υ = 3 or 4 at 193 nm and at υ = 2 at 222 nm. From the angular distribution of the H fragments it can be concluded that the anisotropy parameter β decreases with increasing wavelength. These results can be explained by a predissociation mechanism. Excitation in the first continuum takes place from the ¹A₁ ground state to the bound ¹B₁ state. This state is predissociated by a repulsive ¹A₂ state producing electronically ground-state H and HS fragments, of which the HS fragments can be vibrationally excited, resulting in a bimodal vibrational distribution. The increase of β with increasing wavelength is caused by a non-negligible lifetime in the ¹B₁ state.