Kantowski-Sachs cosmological models with anisotropic dark energy

The exact solutions of the Einstein field equations for dark energy in Kantowski-Sachs metric under the assumption on the anisotropy of the fluid are obtained for exponential and power-law volumetric expansions. The isotropy of the fluid, space and expansion are examined.     

Magnesium-induced regiospecific C-silylation of suitably substituted enoates and dienoates

The β-aryl-β-silyl and β,β-disilyl propionates have been synthesized from cinnamates and β-silyl acrylates by a regiospecific reductive C-silylation using Mg/silyl chloride/DMF system at room temperature. These reductive C-silylation conditions have also been applied to δ-aryl substituted dienoates wherein silylation took place at the δ-position leading to the synthesis of single regioisomeric allylsilanes with very high stereoselectivity.     

Stabilization of ferromagnetism in Mn doped ZnO with C co-doping

We present a method for stabilizing ferromagnetism in Mn doped ZnO. We find that Mn doped ZnO show anti-ferromagnetic order in the absence of additional carriers. When Mn doped ZnO is co-doped with C atom at O sites ferromagnetic state gets stabilized. The C doping creates holes which leads to stabilization of ferromagnetic state via hole mediated double exchange mechanism.     

A study of self-quenching of lyoluminescence yield from gamma-irradiated saccharides and amino acids

Tissue equivalent (TE) lyoluminescence (LL) dosimetry requires practical amount of phosphor for dissolution, typically 5-30 mg. Pronounced mass quenching effect has been observed even in the region of 5 mg, in the cases of LL of lactose-monohydrate, d-glucose, d-mannose, raffinose, sucrose and 1-glutamine. Ordinary concentration-quenching is non-existent but yield per mg falls rapidly with increasing mass of the phosphor. The curves have been fitted with a self-absorption type formula. A well-recognised dose effect is present in quenching curves. The role of free radicals at high radiation doses has been discussed in the contribution of dose effect in quenching.     

High-resolution frequency estimation technique for recovering phase distribution in interferometers

An integral approach to phase measurement is presented. First, the use of a high-resolution technique for the pixelwise detection of phase steps is proposed. Next, the robustness of the algorithm that is developed is improved by incorporation of a denoising procedure during spectral estimation. The pixelwise knowledge of phase steps is then applied to the Vandermonde system of equations for retrieval of phase values at each pixel point. Conceptually, our proposal involves the design of an annihilating filter that has zeros at the frequencies associated with the polynomial that describes the fringe intensity. The parametric estimation of this annihilating filter yields the desired spectral information embedded in the signal, which in our case represents the phase steps. The proposed method offers the advantage of extracting the interference phase of nonsinusoidal waveforms in the presence of miscalibration error of the piezoelectric transducer. In addition, in contrast to previously reported methods, this method does not require the application of selective phase steps between data frames for nonsinusoidal waveforms.     

Maximum-likelihood estimator for dual phase extraction in holographic moire

A maximum-likelihood (ML) method based on spectral estimation theory for the extraction of dual phase distributions in holographic moire in the presence of nonsinusoidal waveforms, noise, and the miscalibration of piezoelectric (PZT) devices is proposed. The extraction of these phases requires incorporating two PZTs into the moire setup. ML estimators are asymptotically efficient for sufficient data samples. The approach presented uses a direct stochastic algorithm called probabilistic global search Lausanne for minimizing the ML function.     

Stereospecific peptide folds. A rationally designed molecular bracelet

A canonical planar beta-hairpin peptide, stereochemically reengineered into a semicircular bracelet type motif by L-to-D stereochemical inversion in two pairs of its cross-strand neighbor residues, displays protein like ordering including two-state behavior in H2O, which is unusual for a small peptide of this size.