Determination of atenolol in human urine by gas chromatography-mass spectrometry method

A sensitive and efficient method was developed for the determination of atenolol in human urine by gas chromatography-mass spectrometry (GC-MS). Atenolol and metoprolol (internal standard, IS) were extracted from human urine with a mixture of chloroform and butanol at basic pH with liquid-liquid extraction. The extracts were derivatized with N-Methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) and analyzed by GC-MS using a capillary column. The standard curve was linear (r = 0.99) over the concentration range of 50-750 ng/mL. Intra- and inter-day precision, expressed as the relative standard deviation were less than 5.0%, and accuracy (relative error) was better than 7.0%. The analytical recovery of atenolol from human urine has averaged 91%. The limit of quantification was 50 ng/mL. Also, the method was successfully applied to a patient with hypertension who had been given an oral tablet of 50 mg atenolol.     

Solubilization of triphenylamine, triphenylphosphine, triphenylphosphineoxide and triphenylmethanol in single and binary surfactant systems

Solubilization and co-solubilization of triphenyls (TPs) viz., triphenylphosphine (TPP), triphenylphosphineoxide (TPPO), triphenylamine (TPA) and triphenylmethanol (TPM) were studied in various single and binary surfactant systems at 25 °C using UV-visible spectroscopy and HPLC. The solubilization capacities of different micelles towards TPs were found to be a function of the nature and structure of solubilizates, locus of solubilization, size of micelles and the nature of interactions between the solubilizate and micelles. The effect of surfactant mixing on the solubilization of TPs was evaluated using the Regular Solution Approach (RSA). The solubility enhancement of TPs within mixed micelles relative to that observed in single surfactant systems was explained in light of the structural micellar changes associated with the mixing of ionic and non-ionic surfactants. Moreover, kinetics of oxidation of TPP by hydrogen peroxide investigated in these surfactant systems was found to be sensitive to the nature of micelle and the locus of solubilization of TPP within the micelles.     

Analysis of Heavy Metals in Scalp Hair Samples of Hypertensive Patients by Conventional and Microwave Digestion Methods

The abnormal metabolism of metal ions plays an important role in health and disease conditions, and studies about them have been attracting significant interest. The aim of our study was to assess the heavy metals (cadmium, copper, iron, nickel, chromium, lead, and zinc) in scalp hair samples of 200 hypertensive (HT) patients of an urban population together with 215 non‐hypertensive male subjects in the age group of 30–60 years. Hair samples were digested with conventional wet ashing and microwave digestion. Analyses of both digests were done by flame and graphite furnace atomic absorption spectrometry. The validity of methodology was checked by use of the certified reference material (CRM 397) hair, provided the Community Bureau of Reference, Commission of the European Communities. According to a statistical evaluation of the results, the microwave digestion method was a valid alternative to the conventional acid digestion method, p value >0.05, but it gave a faster digestion. The overall metal recoveries were 96–98% of those obtained with microwave digestion. Among the toxic elements determined, levels of nickel, cadmium, copper, chromium, and lead in scalp hair samples of hypertensive patients were significantly higher compared normal male subjects, whereas the essential elements such as iron and zinc were found to be low compared age‐matched non‐hypertensive subjects.     

Lanczos Potential for Arbitrary Petrov Type II Spacetimes

The Lanczos potential for an arbitrary Petrov type II spacetime has been obtained and Robinson–Trautman family of metrics has been considered as an example.     

Structural,electronic, and optical properties of Cd-halide-based inorganic LiCdX3 (X = F,Cl) perovskites for photovoltaic applications: A density functional theory study

Halide base perovskite LiCdX₃ (X = F, Cl) is tested by CASTEP (Cambridge Serial Total Energy Package) based on density function theory (DFT). The presented discussion is to explore the structural, electronic, and optical properties of LiCdX₃ (X = F, Cl). The calculated values of the lattice parameter are found to be 3.8 Å and 5.27 Å of LiCdF₃ and LiCdCl₃ respectively. The ideal structure of LiCdX₃ (X = F, Cl) is cubic and dynamically stable. Electronic properties show that materials are semiconductors. The results from band structure are further evaluated by the total and partial density of states. The partial and total density of states confirms the degree of localization of electrons. In optical properties, the highest absorption coefficient is observed in LiCdCl₃. The material is half metallic and has a narrow indirect band gap which may be used in photovoltaic applications.     

A functional equation involving comparable weighted quasi-arithmetic means

We discuss the functional equation $$f(M(x,y))=f(N(x,y)) \qquad (x,y\in I) $$ where I is a nonvoid open subinterval of the set of real numbers ?, f:?I??? is an unknown function, and M, N are weighted quasi-arithmetic means on?I. Our typical assumption will be that M and N are comparable. Complete solution will be presented under the additional supposition that f is the product of the generating functions of?M and?N, respectively.     

Ionically Self-Assembled, Multi-Luminophore One-Dimensional Micro- and Nanoscale Aggregates of Thiacarbocyanine GUMBOS

Groups of uniform materials based on organic salts (GUMBOS), derived from thiacarbocyanine (TC)-based dyes with increasing methyne chain lengths, were prepared through a single-step metathesis reaction between the iodide form of the TC dye and lithium bis(perfluoroethylsulfonyl)imide as the lipophilic anion source. Ionic self-assembly of these fluorescent hydrophobic GUMBOS resulted in aqueous dispersions of one-dimensional micro-and nano-scale molecular aggregates. Blended binary and ternary aggregates containing multiple TC GUMBOS were also prepared. These nanostructures exhibited a variety of aspect ratios, affording tunable F?rster resonance energy transfer (FRET) and aggregation-dependent spectroscopic properties.     

Two-Component Two-Compressible Flow in a Porous Medium

We prove existence of solutions of a two-compressible (liquid and gas) phase flow model in porous media with two components (water and hydrogen). This model is obtained by writing the mass conservation for each component in each phase. We suppose that the mass exchange between dissolved hydrogen and hydrogen in the gas phase is supposed finite. This mass exchange is modeled by a source term on each mass conservation equations.     

Nanoresolution interface studies in thin films by synchrotron x‐ray diffraction and by using x‐ray waveguide structure

In the last years we performed several measurements with synchrotron radiation of several facilities to reveal interesting interface phenomena on the nanoscale. We used both x‐ray diffraction [1] , [2] (XRD) and spectrometry techniques. In this paper, we briefly summarize the results obtained from diffraction measurements, which lead us to our recent grazing incidence x‐ray fluorescence analysis (GIXRF) and extended x‐ray absorption fine structure (EXAFS) experiments. We show how a combination of experimental methods of GIXRF analysis and EXAFS spectroscopy in fluorescence detection with x‐ray standing waves (XSW) technique was applied for the depth profiling of a‐Si/Co/a‐Si layers with nanometer resolution to monitor the growth of CoSi intermetallic phase. The investigated layers were placed into the waveguide structure formed by two Ta films to increase sensitivity and accuracy of the measurements. Copyright © 2009 John Wiley & Sons, Ltd.