Spontaneous formation of vesicles and chiral self-assemblies of sodium N-(4-dodecyloxybenzoyl)-L-valinate in water

A novel N-acylamino acid surfactant, sodium N-(4-dodecyloxybenzoyl)-L-valinate (SDLV), has been synthesized. The aggregation behavior of the surfactant in aqueous solution has been studied by surface tension, fluorescence probe, microscopy, and dynamic light scattering (DLS) techniques. The amphiphile has a very low critical aggregation concentration (cac). These studies have suggested formation of large bilayer structures in water. The mean apparent hydrodynamic radius, RH, of the self-assemblies in dilute aqueous solution obtained from DLS measurements confirmed formation of large aggregates. The FT-IR spectra of the amphiphile have indicated strong intermolecular amide hydrogen bonding in the self-assemblies in aqueous solution. The microenvironment of the fluorescence probes is highly nonpolar and viscous in nature. The circular dichroism (CD) spectra of SDLV were recorded in water and in a 1:1 water-methanol mixture. The CD spectra have indicated the presence of chiral aggregates in aqueous solution above the cac. The microstructure of the aggregates has been studied by use of optical and transmission electron microscopy. Both types of micrographs have shown the presence of a variety of morphologies including giant spherical vesicles, tubules, twisted ribbons, and helical strands in aqueous solutions.     

Radiogenic heavy minerals in Chhatrapur beach placer deposit of Orissa, southeastern coast of India

The beach placer deposit at Chhatrapur coast of Orissa state, southeastern coast of India, has a significant concentration of radiogenic heavy minerals. The average activity concentrations of radioactive elements such as ²³²Th, ²³⁸U and ⁴⁰K were measured by gamma ray spectrometry using a HPGe detector, and found to be 2650±50, 400±30 and 120±30 Bq/kg, respectively, for the bulk sand samples. The activity concentrations in monazite and zircon sands are found to be 305,000±2000 and 2000±150 Bq/kg for the ²³²Th and 21,500±300 and 3450±250 Bq/kg for the ²³⁸U. Electron probe microanalysis results of monazite sands show the average ThO₂ and UO₃ concentrations to be 10.42 wt.%, and 0.32 wt.%, respectively. The major contributors for the enhanced level of radioactivity are monazite and zircon sands. These heavy mineral sands were derived from the nearby source areas such as Eastern Ghats Group of rocks.     

Determination of time-varying contact length,friction force,torque and forces at the bearings in a helical gear system

This paper deals with determining various time-varying parameters that are instrumental in introducing noise and vibration in a helical gear system. The most important parameter is the contact line variation, which subsequently induces friction force variation, frictional torque variation and variation in the forces at the bearings. The contact line variation will also give rise to gear mesh stiffness and damping variations. All these parameters are simulated for a defect-free and two defective cases of a helical gear system. The defective cases include one tooth missing and two teeth missing in the helical gear. The algorithm formulated in this paper is found to be simple and effective in determining the time-varying parameters.     

Relations between bilinear multipliers on ?n, \mathbbT \mathbb{T} n and ?n

In this paper we prove the bilinear analogue of de Leeuw’s result for periodic bilinear multipliers and some Jodeit type extension results for bilinear multipliers.     

Inclusive and exclusive measurements in the projectile breakup of 7Li

The inclusive and exclusive measurements were carried out for ⁷Li projectile breakup on ²⁷Al target at 48 MeV. In the inclusive data we have observed a broad peak around the beam velocity for alphas and tritons. The exclusive data for alpha-triton coincidences show good agreement with the post-form DWBA theory of breakup reactions.     

Unimolecular Amphiphilic Nanocontainers Based on Dendronized Linear Polymers

Summary: Linear polymeric core, polyethylenimine (PEI), is successfully dendronized divergently using different‐generation polyamidoamine (PAMAM)‐type dendrons. The formed dendronized polymers are further end‐capped using long alkyl acrylate, hexyl acrylate, to give macromolecular amphiphiles, which perform as unimolecular nanocontainers, capable of encapsulating water‐soluble dye in their interiors. The encapsulation properties are found to be generation‐dependent, in which, at higher generations of nanocontainers, the cavity becomes more localized, due to dense packing of the dendrons at their termini.

Dendronization of a linear polymeric core followed by capping with hydrophobic arms.     

Transmission electron microscopy and Rutherford backscattering spectrometry studies of Ag2Te films formed from Ag‐Te thin film couples

Formation of Ag₂Te thin films from room temperature (300 K) solid state reaction of Ag and Te thin film couples is investigated. Rutherford Backscattering Spectrometry (RBS) studies confirmed the complete miscibility of the couples and the stoichiometry of the resulting Ag₂Te. Structural analysis by Transmission Electron Microscopy (TEM) showed a fine‐grained structure with monoclinic and orthorhombic phases. Annealing at high temperatures resulted in the growth of giant crystallites with monoclinic phase at random sites. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Variable magnetic field and temperature magnetic force microscopy

Magnetic force microscopy (MFM) studies of epitaxial MnAs films on GaAs(001) have been performed as a function of the applied magnetic field and the sample temperature. For this purpose, we combined a stable variable-temperature sample stage with a compact magnet assembly to fit a commercial magnetic force microscope. In order to keep the thermal drift that affects MFM measurements low, we employed a permanent magnet that can be rotated in a yoke assembly guiding the magnetic flux to the sample. PACS 68.37.Rt; 68.35.Rh; 75.70.-i; 75.70.Kw     

Non-static plane symmetric cosmological models in bimetric theory

The problems of non-static plane symmetric meson field and mesonic perfect fluid in Rosen’s [Gen. Rel. Grav., Vol. 4 (1973) 435] bimetric theory of gravitation are considered. It is observed that plane symmetric non-static cosmological model exists in case of scalar meson field where the scalar field becomes constant. Further it is found that in case of mesonic perfect fluid, the bimetric theory does not admit perfect fluid but allows only mesonic scalar field with constant scalar field. In both the cases a cosmological model with constant scalar field is obtained.