Mixing and magnetic properties of surface alloys: The role of the substrate

In this paper, we have performed ab initio density functional theory calculations to compare the miscibility and magnetic properties of two-dimensional binary surface alloys of the form M_xN_1−x (M = Fe or Co; N = Pt, Au, Ag, Cd or Pb) on two different substrates - Rh(1 1 1) and Ru(0 0 0 1). The trends in miscibility for the two substrates are found to be strikingly similar. The magnetic moments show qualitatively similar behavior, but their magnitudes differ: surface alloys on Rh(1 1 1) have larger magnetic moments than on Ru(0 0 0 1). We infer that strain plays the determining role in stabilizing these two-dimensional alloys, whereas the differences in magnetic moments can be ultimately attributed to the different number of d-electrons in Rh and Ru.     

Low-frequency static characterization of microstructures using acousto-optic modulated stroboscopic interferometer

Micro-electro-mechanical-systems (MEMS) structures such as microcantilevers, micromirrors, accelerometers, gyroscopes, and filters are some of the new types of integrated electro-mechanical microstructures in need of testing tools to measure precisely their static and dynamic properties. The acousto-optic-modulated-stroboscopic-interferometer (AOMSI) is an innovative tool that can be employed to investigate the above-mentioned characteristics for a given environmental condition. In this work, an optical non-contact system employing an acousto-optic-modulator (AOM) to conduct low frequency static characterization of MEMS microstructures is presented. The method is applied to a silicon-on-insulator (SOI) cantilever for demonstration purposes. The theoretical analysis is based on an energy approach. Experimental results are presented and compared with the theory, and are found to be in good agreement.     

Temperature dependent positron annihilation studies in Nafion-117 polymer

We have measured the S-parameter and life-time as a function of temperature from 15 to 300 K in acid Nafion-117. In addition, high temperature measurements from 300 to 550 K have been carried out in acid as well as Cs neutralised Nafion membrane. The results are discussed.     

Transition metal complexes of a potential anticancer quinazoline ligand

A new heterocycle, namely 2-(furyl)-3-(furfuralimino)-1,2-dihydroquinazolin-4(3H)-one (ffdq) was formed by the condensation of 2-aminobenzoylhydrazide with furfural and characterized by physico-chemical, spectroscopic, and single crystal X-ray diffraction studies. A series of complexes of ffdq have been synthesized and characterized by physico-chemical, spectroscopic, and thermal studies. According to the i.r. and ¹H-n.m.r. spectra ffdq behaves as a bidentate ligand coordinating through quinazoline oxygen and azomethine nitrogen. The FAB-mass spectrum of the Cd(II) complex indicates the monomeric nature of this complex. The X-band e.p.r. spectrum of the Cu(II) complex and thermal stabilities of the Co(II) and Ni(II) complexes are discussed.     

Determination of Essential Elements in Ayurvedic Medicinal Leaves by k0 Standardized Instrumental Neutron Activation Analysis

Elemental concentrations of a few medicinal leaves are determined by instrumental neutron activation analysis using the single comparator (k ₀) method. Data obtained for neem leaves, collected from two different places, have been used to see the effect of soil condition. The applicability of the method particularly for the simultaneous determination of Ca, Mg, V and Al in biological matrices has been evaluated in terms of the detection limit, precision and accuracy. The method was validated by analysing the NIST Standard Reference Material (SRM-1571) and it was found that the elemental concentrations measured in SRM-1571 are within ±10% of the reported values.     

Extended time range modeling of myelin growth

When some poorly water-soluble solid surfactants are contacted with water, several microstructures are observed as part of the dissolution process of the surfactants in water. One such microstructure called "myelin," which is observed when a surfactant like phosphatidylcholine is contacted with water, is the subject of this paper. In this study we have used video microscopy to investigate myelin growth over a wide time range, namely 0.25-700 s, and found that existing models do not correctly express myelin growth over extended time ranges. When studied over a wide time range, the myelin growth was found to evolve over three distinct regimes, namely ballistic, diffusional, and subdiffusional regimes. The underlying growth models are physically explained and mathematically expressed. A relationship is derived between the width of myelin and the growth rate at long times. The estimated width of myelin is consistent with experiments.     

Spontaneously broken spacetime symmetries and Goldstone's theorem

Goldstone's theorem states that there is a massless mode for each broken symmetry generator. It has been known for a long time that the naive generalization of this counting fails to give the correct number of massless modes for spontaneously broken spacetime symmetries. We explain how to get the right count of massless modes in the general case, and discuss examples involving spontaneously broken Poincaré and conformal invariance.