Structural and dynamical characterization of unilamellar AOT vesicles in aqueous solutions and their efficacy as potential drug delivery vehicle

Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) is well known to form nanometre sized aqueous droplets in organic solvents and used in several contemporary applications including templates of nanoparticle synthesis. However, the detailed structural characterization of AOT in aqueous media is relatively less attended. Here we have used dynamic light scattering technique for the structural characterization of AOT in aqueous solutions and found to have a monodispersed, unilamellar vesicles (～140 nm diameter). The efficacy of the vesicle to host both charged drugs like H258 (2'-(4-hydroxyphenyl)-5-[5-(4-methylpiperazine-1-yl)-benzimidazo-2-yl-benzimidazole]), EtBr (ethidium bromide) and hydrophobic drug like DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran) has also been investigated using F?rster resonance energy transfer. Picosecond resolved and polarization gated spectroscopy have been used to study the solvation dynamics and microviscosity at the surface of the vesicles. We have also performed concentration and temperature dependent studies in order to confirm the stability of the vesicles in aqueous phase. The drug release profile of the vesicles has been studied through in vitro dialysis method. The non-toxic, monodispersed vesicles in aqueous media with a noteworthy stability in wide range of AOT concentration and temperature, capable of hosting drugs of various natures (both hydrophobic and charged) simultaneously for many codelivery applications with controlled drug release profile may find its applications in drug delivery.     

Synthesis and characterization of in situ nanocrystalline intermetallic phase reinforced AlTiSi amorphous matrix composite

Composites with partially amorphous matrix were synthesized by mechanical alloying of an Al₅₀Ti₄₀Si₁₀ elemental powder blend in a high energy planetary ball-mill, followed by high pressure (8 GPa) low temperature (350–450°C) sintering. Microstructural studies and compositional micro-analysis were carried out using scanning and transmission electron microscopy, and energy dispersive spectroscopy, respectively. Phase evolution as a function of milling time and isothermal temperature and their thermal stability was determined by X-ray diffraction at room or elevated temperature and differential scanning calorimetry, respectively. The microstructure of composites sintered between room temperature and 450°C showed nano-size (≈50 nm) crystalline precipitates of Al₃Ti dispersed in an amorphous matrix. The composites sintered at 400°C with 8 GPa pressure exhibited the highest density (3.58 Mg/m³), nanoindentation hardness (8.8 GPa), Young's modulus (158 GPa) and compressive strength (1940 MPa). A lower hardness and modulus on sintering at 450°C is attributed to additional amorphous to nanocrystalline phase transformation and partial coarsening of Al₃Ti.     

Formation and stability of coreless vortex dipoles in phase-separated binary condensates

We study the motion of the Gaussian obstacle potential created by a blue detuned laser beam through a phase-separated binary condensate in the pancake-shaped traps. We show that phase-separated binary condensates like ⁸⁵Rb–⁸⁷Rb, with appropriate interaction parameters, can be used experimentally to create obstacle assisted droplet and coreless vortex dipoles. We theoretically analyze the energetic stability of condensates with normal and coreless vortices. We confirm our analytic and semi-analytic results by numerical solutions of coupled Gross–Pitaevskii equations.     

Synthesis, crystal structure and DFT studies of N-(4-acetyl-5,5-dimethyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide

The title compound N-(4-acetyl-5,5-dimethyl-4,5-dihydro-1,3,4-thiadiazol-2-yl)acetamide (III) was obtained from the reaction of 2-(propan-2-ylidene)hydrazinecarbothioamide (II) with acetic anhydride instead of formation of the desired thiosemcarbazide derivative of Meldrum acid. The structures of II and III were established by elemental analysis, IR, NMR, Mass and X-ray crystallographic studies. II crystallizes in triclinic system, sp. gr. $P - \bar 1$ Z = 2; III crystallizes in the monoclinic system, sp. gr. P2₁/c, Z = 8. Density functional theory (DFT) calculations have been carried out for III. ¹H and ¹³C NMR of III has been calculated and correlated with experimental results.     

Pricing and risk management of interest rate swaps

This paper reformulates the valuation of interest rate swaps, swap leg payments and swap risk measures, all under stochastic interest rates, as a problem of solving a system of linear equations with random perturbations. A sequence of uniform approximations which solves this system is developed and allows for fast and accurate computation. The proposed method provides a computationally efficient alternative to Monte Carlo based valuations and risk measurement of swaps. This is demonstrated by conducting numerical experiments and so our method provides a potentially important real-time application for analysis and calculation in markets.     

On the Approximation of the SABR Model: A Probabilistic Approach

Abstract

In this article, we derive a probabilistic approximation for three different versions of the SABR model: Normal, Log-Normal and a displaced diffusion version for the general case. Specifically, we focus on capturing the terminal distribution of the underlying process (conditional on the terminal volatility) to arrive at the implied volatilities of the corresponding European options for all strikes and maturities. Our resulting method allows us to work with a variety of parameters that cover the long-dated options and highly stress market condition. This is a different feature from other current approaches that rely on the assumption of very small total volatility and usually fail for longer than 10 years maturity or large volatility of volatility (Volvol).     

A Magneto-Visco-Elastic Model for Magnetorheological Elastomers

In this work we present the modular construction and FEM implementation of a material model for magnetorheological elastomers (MRE) that is firmly rooted in micromechanics and performs well against experimental data. Keeping in mind the composite nature at the microscale, we develop a constitutive formulation based on a multiplicative magneto-mechanical split of the deformation gradient. We consider both Lee- and Clifton-type right and left decompositions. In contrast to other recent formulations [6], this general approach allows the use of highly advanced micromechnically-based network models for polymers such as [4] and [5] in a modular format and to extend its application for coupled magnetomechanical response. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

External leg amputation in conformal-invariant three-point function

Amputation of external legs is carried out explicitly for the conformal-invariant three-point function involving two spinors and one vector field. Our results are consistent with the general result that amputating an external leg in a conformal-invariant Green function replaces a field by its conformal partner in the Green function. A new star-triangle relation, involving two spinors and one vector field, is derived and used for the calculation.     

Novel approach towards one pot stereospecific synthesis of carbohydrate derived substituted imidazolines

A simple synthetic approach has been developed towards one pot synthesis of 2-imidazolines under mild acidic conditions from N-acetyl glucosamine via reductive amination followed by dehydrative cyclization. Synthetic studies were explored in detail with different amines and sugar derivatives. While the conversion was good, the corresponding substituted imidazolines were obtained in moderate yields.     

Characterization of the Phase Mixture Comprising Sodium Hafnate and Hafnia

Solid state electrochemical and XRD studies reveal that the phase relation between Na₂HfO₃ and HfO₂ in the temperature region below about 600 °C is governed by the existence of a third phase disregarded so far, i.e. non‐stoichiometric Na‐modified cubic HfO₂, which is intermediate in terms of the sodium oxide chemical potential.