Mn site substitution of La0.67Ca0.33MnO3 with closed shell ions: Effect on magnetic transition temperature

Mn site is substituted with closed shell ions (Al, Ga, Ti, Zr and a certain combination of Zr and Al) and also with Fe and Ru ions carrying the magnetic moment (S=5/2 and 2 respectively) at a fixed concentration of 5 at %. Substitution did not change either the crystal symmetry or the oxygen stoichiometry. All substituents were found to suppress both the metal-insulator and ferromagnetic transition temperatures (T _p(ρ) and T _C, respectively) to varied extents. Two main contributions identified for the suppression are the lattice disorder arising due to difference in the ionic radii between the substituent (r _M) and the Mn³⁺ ion (r _Mn ³⁺) and in the case of the substituents carrying a magnetic moment, the type of magnetic coupling between the substituent and that of the neighboring Mn ion.     

Analysis theory of random energy of train derailment in wind

Based on the analysis theory of random energy of train derailment, an analysis theory of random energy of train derailment in wind is suggested. Two methods are proposed -the time domain method and the frequency domain method of analysis theory of random energy of train derailment in wind. The curves of σ pw -v under various wind speeds are obtained through the computation. The original curve of σ p -v is expanded, which turns the analysis theory of random energy of train derailment into the all-weather theory. Train derailment condition has been established under wind action. The first and second criterions of train derailment have been proposed in light of wind action. The analysis of train derailment cases at home or abroad is made, in- cluding the first analysis of Xinjiang train derailment case encountered 13-level of gale, which explained the inevitability of train derailment. The analysis theory of random energy of train derailment in wind shows its validity and accuracy. The input energy σ pw of the transverse vibration of train-track(bridge)-wind system is linked to train speed. With the establishment of the analysis theory of random energy of train derailment in wind, It is likely to initiate an all-weather speed limit map for a train or any high-speed train.     

NUMERICAL METHODS FOR MISCIBLE DISPLACEMENT IN POROUS MEDIA INFLUENCED BY MOBILE WATER AND IMMOBILE WATER

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Optical and ODMR Studies of Luminescent Halo(dimethylphenylphosphine)gold(I) Crystals

Crystals of {(Me(2)PhP)AuX}(n) (Me = methyl; Ph = phenyl; X = Cl, Br, I; n = 2, 3) show emission from two excited states. Both states are assigned a triplet multiplicity, on the basis of their lifetimes and zero-field splittings. The structured, higher energy emission originates at approximately 360 nm and has the greater relative intensity at low temperatures. It is assigned as intraligand phosphorescence from a phenyl-localized (3)pipi state. The unstructured, lower energy emission has a peak wavelength that varies in the range 630-730 nm. It is assigned as phosphorescence from the triplet state due to the gold-based sigma(p) <-- sigma(s,d) excitation. The corresponding singlet state is observed at 290-310 nm. The results of SCF-Xalpha-SW calculations on the model complexes H(3)PAuX and (H(3)PAuX)(2) are also presented.     

Experimental evidence of time-delay-induced death in coupled limit-cycle oscillators

Experimental observations of time-delay-induced amplitude death in two coupled nonlinear electronic circuits that are individually capable of exhibiting limit-cycle oscillations are described. The existence of multiply connected death islands in the parameter space of coupling strength and time delay for coupled identical oscillators is established. The existence of such regions was predicted earlier on theoretical grounds [Phys. Rev. Lett. 80, 5109 (1998); Physica (Amsterdam) 129D, 15 (1999)]. The experiments also reveal the occurrence of multiple frequency states, frequency suppression of oscillations with increased time delay, and the onset of both in-phase and antiphase collective oscillations.     

Solid State Structures and Gold-Gold Bonding in Luminescent Halo(dimethylphenylphosphine)gold(I) Complexes

The structures of the series of two-coordinate gold(I) complexes {(Me(2)PhP)AuX}(n) where X is Cl, Br, or I have been examined by X-ray diffraction. The chloro complex crystallized in two separate polymorphic forms. Colorless hexagonal blocks of {(Me(2)PhP)AuCl}(3) crystallized in the monoclinic space group P2(1)/m with a = 12.141(4) ?, b = 8.433(2) ?, c = 14.834(3) ?, and beta = 94.15(2) degrees at 130 K with Z = 2. Refinement of 2837 reflections and 177 parameters yielded R = 0.066 and R(w) = 0.069. The complex consists of three nearly linear P-Au-Cl units that are connected by Au-Au contacts at 3.091(2) and 3.120(2) ?. Colorless prisms of {(Me(2)PhP)AuCl}(2) form in the orthorhombic space group P2(1)2(1)2(1) as described earlier (Cookson, P. D.; Tiekink, E. R. T. Acta Crystallogr. 1993, C49, 1602). The two nearly linear P-Au-Cl units are staggered and connected through a Au-Au bond (3.230(2) ?). Colorless rectangular prisms of {(Me(2)PhP)AuBr}(2) form in the monoclinic space group P2(1) with a = 9.572(5) ?, b = 8.757(3), and c = 12.915(7) at 130 K with Z = 2. Refinement of 2469 reflections with 118 parameters yielded R = 0.080 and R(w) = 0.084. {(Me(2)PhP)AuI}(2) is isomorphous with the bromo complex with a = 9.736(2) ?, b = 8.890(2) ?, and c = 13.160(5) ? at 130 K with Z = 2. Refinement of 2796 reflections with 119 parameters yielded R = 0.052 and R(w) = 0.058. These complexes are similar to the chloro dimer but with altered orientations of the phenyl substituent. The predicted order of ligand effects (Cl > Br > I) on Au-Au distances from quasi-relativistic calculations is borne out in the experimental values: 3.230 ? (Cl); 3.119 ? (Br); 3.104 ? (I). In dichloromethane, these complexes dissociate into monomeric units but there is some evidence for the presence of dimers in concentrated solutions of the iodide compound.     

DSC analysis of Cu–Zn–Sn shape memory alloy fabricated via electrodeposition route

Cu–Zn–Sn shape memory alloy strips with composition range of 13.70–46.30 mass% Sn were fabricated by electrodepositing Sn on a shim brass surface and then subsequently annealed at a constant temperature of 400 °C for 120 min under flowing nitrogen. Subjecting the Sn-plated strips to differential scanning calorimetry (DSC) analysis revealed that the austenitic start (A _s) temperature was essentially constant at 225 °C while the martensite start (M _s) temperature was consistently within the 221.5–222 °C interval. Austenite to martensite phase transformation showed two distinct peaks on the DSC thermogram which can be attributed to the non-homogeneity of the bulk Cu–Zn–Sn ternary alloy. The latent heats of cooling and heating were found to increase with the mass% Sn plated on the shim brass. Effect of annealing temperature was also investigated wherein strips with an essentially constant composition of 26 mass% Sn were annealed at a temperature range of 350–420 °C for 120 min under flowing nitrogen. Varying the annealing temperature has no significant effect on the transformation temperatures of the ternary alloy.