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.     

Fidelity for States of Two Spin- $\frac{1}{2}$ Particles in Moving Frames

Fidelity for the spin part of states of two spin- particles is investigated from the viewpoint of moving observers. Using a numerical approach, the behavior of the fidelity in terms of the boost parameter is described for different amounts of spin entanglement and momentum entanglement. It is shown that for the spin entangled states the fidelity decreases less than that of the case of spin product states and there are special cases for which the fidelity remains perfect regardless of moving observers’ velocity. Generally, in the limit of boosts with speeds close to the speed of light, the fidelity saturates, i.e., it reaches to a constant value that depends on the amount of momentum entanglement and the width of the momentum distribution function.     

MWCNTs/Ionic Liquid/Graphene Quantum Dots Nanocomposite Coated with Nickel‐Cobalt Bimetallic Catalyst as a Highly Selective Non‐enzymatic Sensor for Determination of Glucose

In this work, a glassy carbon electrode (GCE) was modified with multiwall carbon nanotubes/ionic liquid/graphene quantum dots (MWCNTs/IL/GQDs) nanocomposite. Then, the nanocomposite was decorated with nickel‐cobalt nanoparticles (Ni?Co NPs), and it was used as a non‐enzymatic glucose sensor. Field emission scanning electron microscopy, X‐ray diffraction spectroscopy, and energy dispersive spectroscopy were employed to prove the electrodeposition of the Ni?Co NPs on the surface of MWCNTs/IL/GQDs/GCE. Also, cyclic voltammetric and amperometric methods were utilized for the investigation of the electrochemical behaviour of the Ni?Co NPs/MWCNTs/IL/GQDs/GCE for glucose oxidation. The novel amperometric sensor displayed two linear ranges from 1.0 to 190.0 μmol L^?1 and 190.0 to 4910 μmol L^?1 with a low detection limit of 0.3 μmol L^?1 as well as fast response time (2 s) and high stability. Also, the sensor showed good selectivity for glucose determination in the presence of ascorbic acid, citric acid, dopamine, uric acid, fructose, and sucrose, as potential interference species. Finally, the performance of the proposed sensor was investigated for the glucose determination in real samples. Ni?Co NPs/MWCNTs/IL/GQDs/GCE showed good sensitivity and excellent selectivity.     

Compression of antiproton clouds for antihydrogen trapping

Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report the first detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile and its relation to that of the electron plasma.     

An investigation of the use of line widths in quantitative spectrographic analysis

A satisfactory and accurate spectrographic analysis is obtained through the use of line width measurements. The precautions necessary to permit reasonably accurate application of the method are described.     

Reactivity of 4-hydroxy-2-methyl-7,8,9,10-tetrahydrobenzo[h] quinoline towards base-catalyzed cyclization,mannich and turpin reactions

Mannich reaction upon 4-hydroxy-2-methyl-7,8,9,10-tetrahydrobenzo[h]quinoline ( 1 ) as well as its nitration were studied. Condensation of the chloroquinoline 6b with sodium azide, benzylamine and ethanolamine gave the quinoline derivatives 6c, 6f and 6g , respectively. Phenylhydrazine and sodium borohydride effected reduction of the azidoquinoline 6c to the corresponding amino- and hydroxyamino derivatives 6d and 6e , respectively. Also, Turpin's reaction gave the benzoquinobenzoxazines 7a-d when applied to 6b . Treatment of 6f, 6g with alkali and the condensation of 6b with glycine in alcoholic sodium carbonate solution afforded the imidazo[4,5-c]quinoline derivatives 9a-c , respectively.     

Synthesis,crystal structure,vibrational, optical properties,and a theoretical study of a new Pb(II) complex with bis(1-methylpiperazine-1,4-diium): [C5H14N2]2PbCl6·3H2O

An investigation of the solid-state X-ray structure of the new organic–inorganic compound [C₅H₁₄N₂]₂PbCl₆·3H₂O shows a layered organization of the (PbCl₆)^4– anions, with (R₂NH₂)⁺ groups and water molecules developed in the [001 A. Hu, H.L. Ngo, W. Lin. J. Am. Chem. Soc., 125, 11490 (2003).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] plane at x = (2n?+?1)/4. The crystal structure is stabilized by N???H···Cl, N???H···O, O???H···Cl, O???H···O, and C???H···Cl hydrogen bonds. The powder X-ray diffraction and X-ray photoelectron spectroscopic (XPS) analyses confirm the phase purity of the crystal sample. The intermolecular contacts are quantified using the Hirshfeld surfaces computational method. The major inter-contacts contributing to the Hirshfeld surfaces are H…Cl, H…H, and O…H. The vibrational modes were identified and assigned by IR and Raman spectroscopies. The optical properties were investigated by UV–visible and photoluminescence spectroscopic studies. The compound was characterized by thermal analysis to determine its thermal behavior with respect to the temperature. Finally, X-ray photoelectron spectroscopy analysis is reported for analyzing the surface chemistry of [C₅H₁₄N₂]₂PbCl₆·3H₂O.     

Effect of the Preparation Methodof Al–Mg–O Catalysts on the Selective Decomposition of Ethanol

Summary.  Selective decomposition of ethanol was used as a test reaction at 350°C to evaluate the catalytic activity of two Al–Mg–O mixed oxides prepared by two different methods (wet impregnation and coprecipitation). The catalyst precursors were examined by TG and DTA and were calcined between 500–900°C for 5 h in air. The surface area of all catalysts was measured by N₂ sorption using the BET method. The total acidity and basicity were determined by TPD using pyridine and formic acid. The catalysts were characterized by XRD analysis. It was found that the preparation method of Al–Mg–O catalyst has a great effect on the selective decomposition of ethanol. Al–Mg–O (I) catalysts, prepared by wet impregnation, were more selective towards ethene formation during dehydration of ethanol. This is ascribed to their high total surface acidity. On the other hand, Al–Mg–O (II) catalysts, prepared by coprecipitation, were highly selective in the oxidative dehydrogenation of ethanol to yield acetaldehyde. This could be attributed to their high concentration of basic sites. In addition, the production of traces of diethyl ether was also observed (three times more for Al–Mg–O (II) than for Al–Mg–O (I)). Corresponding author. E-mail: shalawy99@yahoo.com Received October 12, 2001. Accepted (revised) January 7, 2002     

Intermolecular association in liquid N-methylacetamide as studied by x-ray scattering

A structural investigation of liquid N methylacetamide was performed at 308 K using x-ray scattering. To extract the molecular form factor F1(q), the geometry of the conformer which has been found in the crystal is considered. The intermolecular structure function DM(q) is interpreted in terms of H-bonding interactions. The crystal N...O distance is taken into accounted and the number of H bond(s) is assumed to be, respectively, equal to one and two. The liquid structure can be described by a linear dimer or chainlike trimer similar to the ones existing in the crystal. The structure factors SM(q) extracted from these clusters fairly agree with the experimental one beyond q=2.5 A(-1).