Solid phase extraction of trace amounts of Pb(II) in opium, heroin, lipstick, plants and water samples using modified magnetite nanoparticles prior to its atomic absorption determination

A new, simple, fast and reliable solid-phase extraction method has been developed for separation/preconcentration of trace amounts of Pb(II) using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles, and its determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after eluting with 4.0?mol?L^?1 HNO₃. Optimal experimental conditions including pH, sample volume, eluent concentration and volume, and co-existing ions have been studied and established. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation of Pb(II) using FAAS technique were 280 (for 560?mL of sample solution), 0.28?ng?mL^?1, 1.4?C70?ng?mL^?1 and 4.6% (for 10?ng?mL^?1, n?=?10), respectively. These analytical parameters using GFAAS technique were 300 (for 600?mL of sample solution), 0.002?ng?mL^?1, 0.006?C13.2?ng?mL^?1 and 3.1% (for 5?ng?mL^?1, n?=?10), respectively. The presented procedure was successfully applied for determination of Pb(II) content in opium, heroin, lipstick, plants and water samples.     

Longifoside-A and -B: two new cerebrosides from Mentha longifolia (Lamiaceae)

Two new N-acyl-glycosphingosines (cerebrosides) named longifoside-A {6'-tetracosenamide, N-[3,4-dihydroxy-1-(hydroxymethyl)-2-(beta-D-glucopyranosyl) heptadecyl]-(6'E)} and B {6'-tetracosenamide, N-[3-hydroxy-1-(hydroxymethyl)-2-(beta-D-glucopyranosyl)-4Z-heptadecenyl]-(6'E)} have been obtained from the methanolic extract of Mentha longifolia belonging to the family Lamiaceae. Both the cerebrosides were purified as their acetate-derivatives: 6'-tetracosenamide, N-[3,4-diacetoxy-1-(acetoxymethyl)-2-(tetraacetoxy-beta-D-glucopyranosyl) heptadecyl]-(6'E) and 6'-tetracosenamide, N-[3-acetoxy-1-(acetoxymethyl)-2-(tetraacetoxy-beta-D-glucopyranosyl)-4Z-heptadecenyl]-(6'E). They were characterized with the aid of 1D and sophisticated 2D-NMR spectroscopic techniques.     

Heteroleptic zinc dipyrromethene complexes

¹H NMR spectroscopy has been used to study the complexation of a per‐alkyl dipyrromethene with zinc acetate. An intermediate, assigned to be the heteroleptic Zn(dipyrromethene)(acetate) complex, is observed under titration conditions although only zinc(dipyrromethene)₂ is obtained after simple work‐up. This indicates that disproportionation occurs during work‐up and that dipyrromethene complexation does not occur under self‐assembled control.     

The Connection Between Isometries and Symmetries of Geodesic Equations of the Underlying Spaces

A connection between the symmetries of manifolds and differential equations is sought through the geodesic equations of maximally symmetric spaces, which have zero, constant positive or constant negative curvature. It is proved that for a space admitting so(n+1) or so(n,1) as the maximal isometry algebra, the symmetry of the geodesic equations of the space is given by so( or (where d ₂ is the two-dimensional dilation algebra), while for those admitting (where represents semidirect sum) the algebra is sl(n+2). A corresponding result holds on replacing so(n) by so(p,q) with p+q = n. It is conjectured that if the isometry algebra of any underlying space of non-zero curvature is h, then the Lie symmetry algebra of the geodesic equations is given by , provided that there is no cross-section of zero curvature at the point under consideration. If there is a flat subspace of dimension m, then the symmetry group becomes ).     

Measurement of soil radioactivity levels and radiation hazard assessment in mid Rechna interfluvial region,Pakistan

Radioactivity levels in soil samples, collected from mid Rechna interfluvial region, Pakistan have been estimated by using gamma ray spectrometric technique. ²²⁶Ra, ²³²Th, the primordial radionuclide ⁴⁰K and the artificial radionuclide ¹³⁷Cs have been measured in the soil of the study area. The mean radioactivity levels of ²²⁶Ra, ²³²Th, ⁴⁰K and ¹³⁷Cs were found to be 49.0 ± 1.6, 62.4 ± 3.2, 670.6 ± 33.9 and 3.5 ± 0.4 Bq kg⁻¹ respectively. The mean radium equivalent activity (Ra_eq), outdoor radiation hazard index (H _out), indoor radiation hazard index (H _in) and terrestrial absorbed dose rate for the area under study were determined as 189.9 ± 8.8 Bq kg⁻¹, 0.51, 0.65 and 70.1 nGy h⁻¹ respectively. The annual effective dose to the public was estimated to be 0.43 mSv. The measured values are comparable with other global radioactivity measurements and are found to be safe for public and environment.     

Exact solutions of second grade aligned MHD fluid with prescribed vorticity

We present here the exact solutions for the equations of magnetohydrodynamic (MHD) aligned flow of a second grade fluid. The exact solutions are constructed for steady and unsteady equations by employing inverse method.     

Volatile components,antioxidant and antimicrobial activity of Citrus acida var. sour lime peel oil

Essential oil of Citrus acida Roxb. var. sour lime was analyzed by GC–MS. Out of 59 components 18 were identified from their fragmentation pattern. Among the identified constituents, o-cymene (16.62%) was found as a major component followed by α-cedrene (10.57%), decadienal (8.043%), bisabolene (5.066%) and β-humelene (4.135%). Citronellyl acetate (2.371%), linalool acetate (2.371%), carvone (1.806%), decanone (1.474%), isopulegol acetate (1.296%), farnesol (1.254%), 4′-methoxyacetophenone (1.207%), and Δ-carene (1.070%) were found in minor quantities whereas α-terpineole (0.607%), dihydroxylinalool acetate (0.650%), cis-nerone (0.574%), caryophyllene oxide (0.433%), and 2,2-dimethyl-3,4-octadienal (0.375%) were found in minute amounts.The antimicrobial activity of the essential oil of C. acida was determined by disc diffusion method, against different bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Enterobacter aerogenes, Salmonella typhymurium) and fungi (Aspergillus ficuum, Aspergillus niger, Aspergillus fumigatus, Aspergillus flavis, Fusarium saloni, Fusarium oxysporum, Pencillium digitatum, Candida utilis). Maximum zone of inhibition was resulted against B. subtilis (22 mm) followed by C. utilis (20 mm) and B. cereus (19.8 mm), whereas the minimum zone of inhibition was shown by P. digitatum (10 mm). The inhibition zones, measured after 48 h and 96 h, showed that it is active against all tested bacteria and fungi. The results of antioxidant activity of essential oil of C. acida var. sour lime showed that it was able to reduce the stable radical DPPH to yellow-colored DPPH-H reaching 91.7% of DPPH scavenging effect comparative to ascorbic acid being a strong antioxidant reagent.     

Lipid classes of in vitro cultivar of Pakistani citrus

The in vitro cultivar of citrus contained 18.0% lipids after 12 weeks of germination of seed. The lipid was analyzed by GC procedure for its fatty acid composition. The oil contained seven major fatty acid constituents which were later identified by GC. The oil was further analyzed for its classes by means of thin layer chromatography and gas chromatography. The major portion of the lipid classes comprised of neutral lipids (93.9%) and polar lipids (6.1%). The identified neutral lipids comprised of hydrocarbon (1.4%), wax esters (1.5%), sterol esters (5.2%), triglycerides (52.3%), free fatty acids (1.3%), 1,3-diglycerides (6.0%), 1,2-diglycerides (5.0%), glycol (15.2%), sterols (6.0%), 2-monoglycerides (6.4%), 1-monoglycerides (5.3%) and the identified polar lipids comprised of phosphatidyl ethanolamine (1.8%) phosphatidyl choline (0.9%) lysophosphatidyl ethanolamine (1.8%) and phosphatidyl inositol (1.1%).     

Energitics of micellizaion of sodium n-dodecyl sulfate at physiological conditions using isothermal titration calorimetry

The curing kinetics of nanocomposites based on phenolic resol cured with triethylamine (TEA) containing different amounts of organic montmorillonite was analyzed by differential scanning calorimetry. Kissinger-Akahira-Sunose (KAS) model-free kinetics has been applied to correlate the dynamic cure behaviour in the presence of modified montmorillonite. The effect in the curing of the use of different clay modifiers has also been studied. A commercial clay with hydroxyl groups (Cloisite 30B) and a customized montmorillonite (PheMMT) whose reactive groups induce condensation reactions with the resol matrix have been used. Strong dependency of activation energy on apparent conversion has been observed for all compounds.     

Electrostatic global vortices in a nonuniform cylindrical magneto-plasma

We present nonlinear properties of the low-frequency nonlinear electrostatic waves in a nonuniform bounded magneto-plasma with the equilibrium density and parallel ion velocity gradients along the radial direction. The existence of electrostatic global vortices in a cylindrical magnetoplasma is established. The present results should help to understand the properties of coherent vortical structures in the presence of a magnetic field-aligned ion flow with a radial ion velocity gradient in laboratory magnetoplasmas that are bounded and nonuniform.