Development of a novel 96-microwell assay with high throughput for determination of olmesartan medoxomil in its tablets

A novel 96-microwell-based spectrophotometric assay has been developed and validated for determination of olmesartan medoxomil (OLM) in tablets. The formation of a colored charge-transfer (CT) complex between OLM as a n-electron donor and 2, 5-dichloro-3, 6-dihydroxy-1, 4-benzoquinone (p-chloranilic acid, pCA) as a π-electron acceptor was investigated, for the first time, and employed as a basis in the development of the proposed assay. The proposed assay was carried out in 96-microwell plates. The absorbance of the colored-CT complex was measured at 490 nm by microwell-plate absorbance reader. The optimum conditions of the reaction and the analytical procedures of the assay were established. Under the optimum conditions, linear relationship with good correlation coefficient was found between the absorbance and the concentration of OLM in the range of 1-200 μg ml^-1. The limits of detection and quantitation were 0.3 and 1 μg ml^-1, respectively. No interference was observed from the additives that are present in the pharmaceutical formulation or from hydrochlorothiazide and amlodipine that are co-formulated with OLM in some formulations. The assay was successfully applied to the analysis of OLM in tablets with good accuracy and precision. The assay described herein has great practical value in the routine analysis of OLM in quality control laboratories, as it has high throughput property, consumes minimum volume of organic solvent thus it offers the reduction in the exposures of the analysts to the toxic effects of organic solvents, and reduction in the analysis cost by 50-fold. Although the proposed assay was validated for OLM, however, the same methodology could be used for any electron-donating analyte for which a CT reaction can be performed.     

Tunable intramolecular multicenter H-bonding interactions in first-row metal complexes bearing bidentate redox-active ligands

Abstract

In this research article, we report the synthesis and structural characterization of a family of first-row metal complexes bearing redox-active ligands with tunable H-bonding donors. We observed that these coordination complexes can adopt three different geometries and that they are stabilized by intramolecular multicenter H-bonding interactions, which are systematically modified by changing the metal ion (Co, Ni, Cu, Zn), the ligand scaffold (variations in the diamine and ureanyl substituents used) and the solvent of crystallization.     

Structure and sensory equipment of the ovipositor of Habrobracon hebetor (Say) (Hymenoptera: Braconidae)

The microsculpture of various structures of the ovipositor of Habrobracon hebetor (Say) (Hymenoptera: Braconidae) is described from scanning and transmission electron microscopy. These include: the ovipositor egg canal, valvillus, seal of the first valvulae, interlocking mechanism (olistheter) connecting the first and second valvulae, an olistheter-like interlocking mechanism connecting the two pieces of the first valvulae, annulation, microtrichia of the third valvulae, and the ovipositor sensory equipment. Better understanding of the microsculpture of these components may make their roles in stinging, oviposition, and the host selection process more clear.     

On a quadratic integral equation with supremum involving Erdélyi‐Kober fractional order

We introduce Erdélyi‐Kober fractional quadratic integral equation with supremum, namely . This equation contains as special cases numerous integral equations studied by other authors. We show that there exists at least one monotonic solution belonging to C[0, 1] of our equation. The main tools in our analysis are Darbo fixed point theorem and the measure of noncompactness related to monotonicity which was introduced by Bana? and Olszowy. Finally, we present an example for illustrating the natural realizations of our abstract results.     

On Erdélyi–Kober Quadratic Functional-Integral Equation in Banach Algebra

Using the technique of a suitable measure of noncompactness in Banach algebra, we prove an existence theorem for some functional-integral equations in Banach algebra, namely Erdélyi–Kober quadratic functional-integral equation. This equation contains as particular cases a lot of integral equations that appear in many branches of nonlinear analysis and its applications. The obtained result is illustrated by an example.     

Economic selection of process mean for single-vendor single-buyer supply chain

Process mean selection for a container-filling process is an important decision in a single-vendor single-buyer supply chain. Since the process mean determines the vendor’s conforming and yield rates, it influences the vendor–buyer decisions regarding the production lot size and number of shipments delivered from the vendor to buyer. It follows, therefore, that these decisions should be determined simultaneously in order to control the supply chain total cost. In this paper, we develop a model that integrates the single-vendor single-buyer problem with the process mean selection problem. This integrated model allows the vendor to deliver the produced lot to buyer in number of unequal-sized shipments. Moreover, every outgoing item is inspected, and each item failing to meet a lower specification limit is reprocessed. Further, in order to study the benefits of using this integrated model, two baseline cases are developed. The first of which considers a hierarchical model where the vendor determines the process mean and schedules of production and shipment separately. This hierarchical model is used to show the impact of integrating the process mean selection with production/inventory decisions. The other baseline case is studied in the sensitivity analysis where the optimal solution for a given process is compared to the optimal solution when the variation in the process output is negligible. The integrated model is expected to lead to reduction in reprocessing cost, minimal loss to customer due to the deviation from the optimum target value, and consequently, providing better products at reduced cost for customers. Also, a solution procedure is devised to find the optimal solution for the proposed model and sensitivity analysis is conducted to investigate the effect of the model key parameters on the optimal solution.     

A pressure-based algorithm for multi-phase flow at all speeds

A new finite volume-based numerical algorithm for predicting incompressible and compressible multi-phase flow phenomena is presented. The technique is equally applicable in the subsonic, transonic, and supersonic regimes. The method is formulated on a non-orthogonal coordinate system in collocated primitive variables. Pressure is selected as a dependent variable in preference to density because changes in pressure are significant at all speeds as opposed to variations in density, which become very small at low Mach numbers. The pressure equation is derived from overall mass conservation. The performance of the new method is assessed by solving the following two-dimensional two-phase flow problems: (i) incompressible turbulent bubbly flow in a pipe, (ii) incompressible turbulent air–particle flow in a pipe, (iii) compressible dilute gas–solid flow over a flat plate, and (iv) compressible dusty flow in a converging diverging nozzle. Predictions are shown to be in excellent agreement with published numerical and/or experimental data.     

Diurnal and Eleven- Year Variations of Neutron Component of Cosmic Rays

Cosmic ray ground observations are used together with the method of coupling coefficients to determine, by spectrographic method, the features of the variational primary energy spectrum of diurnal and eleven-year variations of neutron component of cosmic rays. It is found that the variational energy spectrum responsible for both types of variations can be best described by a constant spectrum up to an upper effective rigidity boundary. The upper cut-off effective rigidity boundary for the variational energy spectrum of diurnal variation was found to change from 105 GV at maximum solar activity to 15.85 GV at minimum solar activity. For Eleven-year variation, R_max was found to have a value of about 20 GV which changes slighly with solar activity due to the change of the coupling coefficients with solar activity.     

Dispersion studies and electronic transitions in nickel phthalocyanine thin films

Thin films of the organic semiconductor nickel phthalocyanine (NiPc) are structurally investigated using X-ray diffraction and infrared light absorption. The optical absorption and dispersion studies of nickel phthalocyanine were investigated using spectrophotometric measurements of transmittance and reflectance at normal incidence in the wavelength range 190–2100 nm. The absorption spectra recorded in the UV-VIS region show two well-defined absorption bands of the phthacyanine molecules, namely, the Soret and the Q-band. The Davydove splitting of the main absorption peak in the metal phthalocyanines correlates with the relative tendencies of the metal to out-of-plane bonding. The refractive index n as well as the absorption index k were calculated and showed an independent of the film thickness in the film thicknesses range 400–770 nm. The refractive index n showed an anomalous dispersion in the absorption region as well as normal dispersion in the transparent region. Some of the important optical absorption such as the molar extinction coefficient, the oscillator strength, the electric dipole strength have been evaluated. The analysis of the spectral behavior of the absorption coefficient α in the absorption region revealed two indirect allowed transitions with corresponding energies 2.77±0.03 and 1.66±0.02 eV. An energy band diagram has been proposed to account for the optical transitions of NiPc thin film. All previous parameters were as well obtained for films annealed at 523 K for 2 h. Discussion of the obtained results and their comparison with the previously published data are also given.