An approach to evaluate the efficiency of γ-ray detectors to determine the radioactivity in environmental samples

This work provides an approach to determine the efficiency of γ-ray detectors with a good accuracy in order to determine the concentrations of either naturally occurring or artificially prepared radionuclides. This approach is based on the efficiency transfer formula(ET), the effective solid angles, the self- absorptions of the source matrix, the attenuation by the source container and the detector housing materials on the detector efficiency. The experimental calibration process was done using radioactive(Cylindrical Marinelli) sources, in different dimensions,that contain aqueous152 Eu radionuclide. The comparison point to a fine agreement between the experimental measured and calculated efficiencies for the(NaI HPGe) detectors using volumetric radioactive sources.     

Stability-Indicating HPLC and RP-TLC Determination of Cefpirome Sulfate with Kinetic Study

Two sensitive and selective stability-indicating methods were developed for the determination of the antibiotic cefpirome sulfate in bulk powder, pharmaceutical formulation and in presence of its acid, alkaline, photo- and oxidative degradation products. Method A was based on HPLC separation of cefpirome sulfate in the presence of its degradation products on a reversed phase column C18, 250 × 4.6 mm, 5-μm particle size and mobile phase consisting of 0.1 M disodium hydrogen phosphate dihydrate pH 3.9 adjusted with phosphoric acid–acetonitrile (85:15, v/v). Quantitation was achieved with UV detection at 270 nm. The linear calibration curve was in the range 5.0–50.0 μg mL^?1. Method B was based on reversed phase TLC separation of the cited drug in the presence of its degradation products followed by densitometric measurement of the intact drug at 270 nm. The separation was carried out using disodium hydrogen phosphate dihydrate 2.0 g %w/v, at pH 3.5 adjusted with phosphoric acid–acetone (15:10, v/v) as a developing system. The calibration curve was in the range of 1.0–10.0 μg/spot. The HPLC method was used to study the kinetic of cefpirome sulfate acid degradation. The results obtained were statistically analyzed and compared with those obtained by applying the official Japanese method.     

A pure geometric approach to stellar structure

The present work represents a step in dealing with stellar structure using a pure geometric approach. Geometric field theory is used to construct a model for a spherically symmetric configuration. In this case, two solutions have been obtained for the field equations. The first represents an interior solution which may be considered as a pure geometric one in the sense that the tensor describing the material distributions is not a phenomenological object, but a part of the geometric structure used. A general equation of state for a perfect fluid, is obtained from, and not imposed on, the model. The second solution gives rise to Schwarzschild exterior field in its isotropic form. The two solutions are matched, at a certain boundary, to evaluate the constants of integration. The interior solution obtained shows that there are different zones characterizing the configuration: a central radiation dominant zone, a probable convection zone as a physical interpretation of the singularity of the model, and a corona like zone. The model may represent a type of main sequence stars. The present work shows that Einstein’s geometerization scheme can be extended to gain more physical information within material distribution, with some advantages.     

Newton-Kantorovich approximations to nonlinear singular integral equation with shift

The paper is concerned with the applicability of some new conditions for the convergence of Newton-kantorovich approximations to solution of nonlinear singular integral equation with shift of Uryson type. The results are illustrated in generalized Holder space.     

Functionalization of the methylene groups of p-tert-butylcalix[4]arene: S-C,N-C,and C-C bond formation

Reaction of the calixarene derivative 7 with two exocyclic double bonds with carbon-, nitrogen-, oxygen-, or sulfur-containing nucleophiles afforded bis(spirodienone) derivatives substituted at two opposite methylene groups in a trans fashion. LiAlH(4) reduction of the bis(spirodienone) derivatives with two methylenes functionalized by thiomethoxy, diethyl malonate, or anilino substituents yielded trans methylene-substituted calix[4]arenes. Upon standing in solution, the calixarene derivative incorporating SMe groups on the bridges underwent trans right harpoon over left harpoon cis isomerization. An equilibration study performed on this calixarene derivative (tetrachloroethane-d(2), 430 K) indicated that the cis isomer is the form of lower free energy.     

Synthesis,Characterization and Antibacterial Activity of a Novel Photoluminescent Nb-Substituted Lindqvist Polyoxotungstate Based Organic Cation

A novel heteropolyoxometalate, Nb-substituted hexatungstate compound; (C₉H₈N)₃[NbW₅O₁₉]·3H₂O triquinolinium μ₆-oxido-dodeca-μ₂-oxidohexaoxido[niobium(V)pentatungsten(VI)]ate trihydrate (QNbW5) has been grown by slow evaporation method and characterized by powder X-ray and single-crystal XRD methods, NMR, IR, UV–Vis and photoluminescence spectroscopy measurements, elemental analysis and thermogravimetric analysis. Single-crystal XRD analyses show that QNbW5 crystallizes in the triclinic space group \({\text{P}}\overline{ 1}\) and its crystal structure consists of 3D grid-like network of components in a close connection through N–H···O, C–H···O and offset π···π stacking interactions between neighboring rings of quinolinium moieties. Moreover, the spectroscopic and electronic properties of QNbW5 have also been investigated showing a considerable important gap energy well confirming the semiconductor behavior and the blue photoluminescent property of reported material. In addition, the complex shows promising antimicrobial activity against four pathogenic microbes in comparison with its components alone.     

In vitro antimicrobial properties and chemical composition of Santolina chamaecyparissus essential oil from Algeria

The chemical composition of the essential oil obtained from the aerial parts of Santolina chamaecyparissus L., growing in Algeria, was investigated by GC-MS analyses. A total of 36 compounds were identified, accounting for 91.7% of the essential oil obtained. Camphor (31.1%) and cubenol (17.0%) were the predominant compounds. The potential of the antimicrobial activity was also investigated and the tested sample proved to be very active against Klebsiella pneumonia and Candida albicans (34.1 +/- 0.02 mm and 35.0 +/- 0.01 mm, respectively). Transverse sections of the leaf and stem of the plant suggest that the essential oil is localized in endogenous and exogenous sites.     

Interaction between alpha and upsilon-crystallin, common to the eye of the Australian platypus, by radical probe mass spectrometry

The interaction between alpha-crystallin and upsilon-crystallin, a class recently discovered in the eye of the Australian platypus, has been shown by native shift gel assay and examined by radical probe mass spectrometry in the context of the ability of alpha-crystallin to protect upsilon-crystallin from oxidation and oxidative damage through radical-based oxidative stress mechanisms. Residues 22-41, 132-148, 212-227 and 245-264 of upsilon-crystallin display the greatest protection when interacted with alpha-crystallin at a ratio of 2 : 1 observed for the complex, which is commensurate with their levels measured in the eye of the platypus. Across each domain, a delay in the onset of oxidative damage is observed as the time of exposure to radicals is increased. The results are discussed in the context of the structure of the porcine homologue of upsilon-crystallin.     

Stability indicating methods for determination of Donepezil Hydrochloride according to ICH guidelines

Stability indicating assays for determination of Donepezil Hydrochloride in presence of its oxidative degradate were developed and validated. The first three are spectrophotometric methods depending on using zero order (D(0)), first order (D(1)) and second order (D(2)) spectra. The absorbance was measured at 315 nm for (D(0)) while the amplitude was measured at 332.1nm for (D(1)) and 340 nm for (D(2)) using deionized water as a solvent. Donepezil Hydrochloride (I) can be determined in the presence of up to 70% of its oxidative degradate (II) using (D(0)), 80% using (D(1)) and 90% using (D(2)). The linearity range was found to be 8-56 microg ml(-1) for (D(0)), (D(1)) and (D(2)). These methods were applied for the analysis of I in both powder and tablet form. Also, a spectrofluorimetric method depending on measuring the native fluorescence of I in deionized water using lambda excitation 226 nm and lambda emission 391 nm is suggested. The linearity range was found to be 0.32-3.20 microg ml(-1) using this method, I was determined in the presence of up to 90% of II. The proposed method was applied for the analysis of I in tablet form as well as in human plasma. The last method depends on using TLC separation of I from its oxidative degradate II and I was then determined spectrodensitometrically. The mobile phase was methanol : chloroform : 25% ammonia (16 : 64 : 0.1 by volume). The linearity range was found to be 2-15 microg/spot. This method was applied to the analysis of I in both powder and tablet form using acetonitrile as a solvent.