HPTLC Determination of Cefpodoxime Proxetil in Formulations

An HPTLC method has been developed that coelutes both the isomers of cefpodoxime proxetil (CFP). CFP was chromatographed on a silica gel 60 F₂₅₄ TLC plate using toluene:acetonitrile (6:4) as a mobile phase and was quantified at 234 nm. The method was validated with respect to linearity, accuracy, precision and specificity. The limit of detection and limit of quantification for CFP were found to be 0.150 and 0.4 μg spot^?1, respectively. The proposed method was successfully used to determine the amount of CFP present in the marketed tablets and self-nanoemulsifying systems.     

Mössbauer effect studies on the formation of iron oxide phases synthesized via microwave–hydrothermal route

Microwave–hydrothermal (MH) route was employed to synthesize various iron oxide phases in ultra-fine crystalline powders by using ferrous sulphate and sodium hydroxide as starting chemicals. All chemical reactions were carried out under identical MH conditions, namely, at 190°C, 154 psi, 30 min, by varying the molar ratio (MR) of FeSO₄/NaOH in the aqueous solutions. The variation of MR has a dramatic effect on the crystallization behavior of various phases of iron oxides under MH processing conditions. For example, spherical agglomerates of Fe₃O₄ powder were obtained if MR equal to 0.133 (pH?>?10 sample A). On the other hand non-stoichiometric Fe₃O₄ powders (Sample B) were obtained for all higher MR of FeSO₄/NaOH between 0.133 and 4.00 (6.6?2O₃ powders (sample C) were produced. Fe⁵⁷ Mössbauer spectra were recorded for all the three sets of samples at room temperature. In the case of sample B, temperature dependent Mössbauer spectra were recorded in the range of 77–300 K to understand the non-stoichiometric nature of Fe₃O₄ powders. All these results are discussed in the present paper.     

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.     

A linear algebraic method for pricing temporary life annuities and insurance policies

We recast the valuation of annuities and life insurance contracts under mortality and interest rates, both of which are stochastic, as a problem of solving a system of linear equations with random perturbations. A sequence of uniform approximations is developed which allows for fast and accurate computation of expected values. Our reformulation of the valuation problem provides a general framework which can be employed to find insurance premiums and annuity values covering a wide class of stochastic models for mortality and interest rate processes. The proposed approach provides a computationally efficient alternative to Monte Carlo based valuation in pricing mortality-linked contingent claims.     

Analysis of the nonlinear vibration of a two-mass–spring system with linear and nonlinear stiffness

An analytical approach is developed for areas of nonlinear science such as the nonlinear free vibration of a conservative, two-degree-of-freedom mass–spring system having linear and nonlinear stiffnesses. The main contribution of this research is twofold. First, it introduces the transformation of two nonlinear differential equations for a two-mass system using suitable intermediate variables into a single nonlinear differential equation and, more significantly, the treatment of a nonlinear differential system by linearization coupled with Newton’s method. Secondly, the major section is the solving of the governing nonlinear differential equation where the displacement of the two-mass system can be obtained directly from the linear second-order differential equation using a first-order variational approach. The aforementioned approach proposed by J.H. He, who actually developed the method, is exactly He’s variational method. This approach is an explicit method with high validity for resolving strong nonlinear oscillation system problems. Two examples of nonlinear two-degree-of-freedom mass–spring systems are analyzed, and verified with published results and exact solutions. The method can be easily extended to other nonlinear oscillations and so could be widely applicable in engineering and science.     

Enhanced field emission from LaB6 thin films with nanoprotrusions grown by pulsed laser deposition on Zr foil

Lanthanum hexaboride (LaB₆) films have been deposited on a zirconium foil by pulsed laser deposition method. The field emission studies of the LaB₆ deposited film have been performed in the planar diode configuration under ultra high vacuum conditions. The Fowler-Nordheim plots were found to be linear in accordance with the quantum mechanical tunneling phenomenon. A typical field emission current of 7.02 μA was drawn at an applied electric field of 2 V/μm. The field enhancement factor is calculated to be 8913 cm⁻¹, indicating that the field emission is from nanoscale protrusions present on the emitter surface. The atomic force microscope (AFM) investigation of the surface clearly shows the conical shaped nanoprotrusions of few hundred nanometers with asperities of 20-40 nm on its top. The emission current-time plot recorded at the pre-set value of emission current of 5 μA over a period of more than 3 h exhibits an initial increase and subsequent stabilization of the current. The results reveal that the LaB₆/Zr field emitter obtained by the pulsed laser deposition (PLD) is a promising cathode material for practical applications in field emission-based devices.     

On the Cauchy problem for the general relativistic perfect magnetofluid

This paper aims at the study of the Cauchy problem for the general relativistic perfect magnetofluid. The consistency and uniqueness condition to be satisfied on the hypersurface by three unknown quantities in the magnetohydrodynamic field equations is obtained. For unit magnetic permeability the result agrees in form with that of Lichnerowicz.