Voltammetric determination of isoprenaline in pharmaceutical preparations using a copper(II) hexacyanoferrate(III) modified carbon paste electrode

The electroanalytical determination of isoprenaline in pharmaceutical preparations of a homemade carbon paste electrode modified with copper(II) hexacyanoferrate(III) (CuHCF) was studied by cyclic voltammetry. Several parameters were studied for the optimization of the sensor such as electrode composition, electrolytic solution, pH effect, potential scan rate and interferences in potential. The optimum conditions were found in an electrode composition (in mass) of 15% CuHCF, 60% graphite and 25% mineral oil in 0.5 mol l⁻¹ acetate buffer solution at pH 6.0. The analytical curve for isoprenaline was linear in the concentration range from 1.96×10⁻⁴ to 1.07×10⁻³ mol l⁻¹ with a detection limit of 8.0×10⁻⁵ mol l⁻¹. The relative standard deviation was 1.2% for 1.96×10⁻⁴ mol l⁻¹ isoprenaline solution (n=5). The procedure was successfully applied to the determination of isoprenaline in pharmaceutical preparations; the CuHCF modified carbon paste electrode gave comparable results to those results obtained using a UV spectrophotometric method.     

Application d'un tétraasamacrocycle greffé sur polymère à l'extraction et au dosage du cuivre en eau de mer

(Application of a polymer-supported tetraazamacrocyle to the extraction of copper from sea water)Copper is extracted with 1,4,8,11-tetraazacyclotetradecane bound to poly(chloromethyl)vinylbenzene. The material has a very low affinity for alkaline and alkaline earth metals. The influence of salinity, pH and temperature on the complexation of copper is described. Results for waters agree well with those obtained with Chelex-100.     

Synthesis of ultrathin and compact Au@MnO2 nanoparticles for shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS)

Shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) based on Au@SiO₂ or Au@Al₂O₃ nanoparticles (NPs) shows great potential to break the long‐standing limitations of substrate and surface generality of surface‐enhanced Raman scattering (SERS). However, the shell of SiO₂ or Al₂O₃ can easily be dissolved in alkaline media, which limits the applications of SHINERS in alkaline systems. Besides that, the synthesis of Au@SiO₂ NPs can be further simplified and Au@Al₂O₃ NPs be replaced by other NPs that are more amenable for mass production. In an attempt to make SHINERS NPs available in any systems practically, we report the synthesis of ultrathin and compact Au@MnO₂ NPs. The shell thickness of MnO₂ can be controlled down to about 1.2 nm without any pinhole. SHINERS based on such Au@MnO₂ NPs exhibits much higher Raman enhancement effect than Au@SiO₂ NPs and can be applied in alkaline systems in which Au@SiO₂ or Au@Al₂O₃ NPs cannot be applied. Copyright © 2011 John Wiley & Sons, Ltd.     

New Antifungal Terpenoid Glycosides from Alibertia edulis (Rubiaceae)

Phytochemical investigation from the stems of Alibertia edulis led to the isolation and identification of a new iridoid 6β‐hydroxy‐7‐epigardoside methyl ester ( 1 ) and a new saponin 3β‐O‐[α‐L ‐rhamnopyranosyl‐(1→2)‐O‐β‐D ‐glucopyranosyl‐(1→2)‐O‐β‐D ‐glucopyranosyl]‐28‐O‐β‐D ‐glucopyranoside pomolate ( 2 ), along with three known compounds, shanzhiside methyl ester ( 3 ), ixoside ( 4 ), and 3,4,5‐trimethoxyphenyl 1‐O‐β‐D ‐apiofuranosyl‐(1→6)‐O‐β‐D ‐glucopyranoside ( 5 ). The structures of 1 and 2 were established on the basis of their spectroscopic data. Iridoid 1 and saponin 2 exhibited moderate inhibitory activities against Candida albicans and C. krusei in a dilution assay.     

High-order perturbation theory for the hydrogen atom in a magnetic field

The states of a hydrogen atom with principal quantum numbers n⩽3 in a constant uniform magnetic field ℋ are studied. Coefficients in the expansion of the energy of these states in powers of ℋ² up to the 75th order are obtained. Series for the energies of the states and the wave functions are summed to values of ℋ on the order of the atomic magnetic field. A generalization of the moment method upon which these calculations are based can be used in other cases in which a hydrogen atom is perturbed by a potential with a polynomial dependence on the coordinates. Zh. éksp. Teor. Fiz. 113, 550–562 (February 1998)     

Elementary methods for an occupancy problem of storage

Summary This paper considers the probabilities of first emptiness in two storage systems. The first, an infinite dam in discrete time, is fed by inputs whose distribution is geometric in unit time-intervals; at the end of each of these, there occurs a unit release. The second is an infinite dam in continuous time with Poisson inputs, for which the release occurs at constant unit rate except when the dam is empty.First emptiness in both dams may be formulated as a special type of classical occupancy problem. The probabilities of emptiness are derived by direct elementary methods, and their generating functions found. These are shown to define proper distributions only if the mean input per unit time does not exceed the corresponding release.     

Needle Sharing Infections among Heterogeneous IVDUS

 This paper begins with an alternative derivation of the coefficients in a known probability generating function (pgf ), namely that for the number of new infectives generated in a random allocation model of needle sharing among i infectives and n susceptibles. The expectation and variance of the number of new infectives are derived. The pgf for such a model is then obtained when there are types of susceptibles; the probabilities of generating new infectives are found for , where the infectives have preferential probabilities p and q for type 1 and 2 susceptibles respectively. The case of variable susceptibilities is also considered, and the paper concludes with some remarks on the pgf method. Received 21 February 2001; in final form 15 September 2001