Determination of trace concentrations of thorium in uranium oxide matrix by epithermal instrumental neutron activation analysis

An epithermal instrumental neutron activation analysis (EINAA) method using cadmium filter was standardized to determine trace concentrations of thorium in four samples of uranium oxide (U₃O₈) samples. Samples and thorium standards, wrapped with cadmium foil, were irradiated at a reactor neutron flux of about 10¹² cm^?2 s^?1. Radioactive assay was carried out using a Compton suppressed anticoincidence gamma ray spectrometer consisting of HPGe-BGO detectors coupled to MCA. Concentrations of thorium in these samples were found to be in the range of 15–72 mg kg^?1. EINAA results were validated by determining thorium concentrations in uranium matrix by standard addition method. EINAA results were compared with those obtained by two wet chemical methods namely ion chromatography (IC) and inductively coupled plasma atomic emission spectrometry (ICP-AES). The results obtained by the three methods were found to be in good agreement, indicating further validity of the proposed EINAA method.     

Role of plant alkaloids on human health: A review of biological activities

Alkaloids are plant secondary metabolite. They are well known nitrogen-containing natural bioactive compounds. Cutting edge research is going on alkaloids to unravel novel therapeutic approaches. Literature reveals that alkaloids contribute multiple biological activities and some alkaloids transform into active metabolites too. In this review, we have focused on marketed and experimental alkaloids. We have summarized sources and biological activities of reported alkaloids in past decades.     

Gas phase reactions induced by OH− ion

The site of proton abstraction by OH^? ion in some 4-substituted-3,5,6-triphenyl-Δ′-cyclohexenes has been established from labelling studies. The further fragmentation mode of (M-H)^? ion depends on its structure and stereochemistry. The $\text{exo}$ and $\text{endo}$ nitro isomers exhibit stereochemical differences in the elimination of HNO₂ while the amino and cyano analogues show stereochemically controlled RDA fragmentation mode.     

Effect of ambient pressure on the crystalline phase of nano TiO2 particles synthesized by a dc thermal plasma reactor

The synthesis of nanoparticles of titanium dioxide (TiO₂) with varying percentages of anatase and rutile phases is reported. This was achieved by controlling the operating pressure in a transferred-arc, direct current thermal plasma reactor in which titanium vapors are evaporated, and then exposed to ambient oxygen. The average particle size remained around 15 nm in each case. The crystalline structure of the as-synthesized nanoparticles of TiO₂ was studied with X-ray diffraction analysis; whereas the particle morphology was investigated with the help of transmission electron microscopy. The precursor species responsible for the growth of these nanoparticles was studied with the help of optical emission spectroscopy. As inferred from the X-ray diffraction analysis, the relative abundance of anatase TiO₂ was found to be dominant when synthesized at 760 Torr, and the same showed a decreasing trend with decreasing chamber pressure. The study also reveals that anatase TiO₂ is a more effective photocatalytic agent in degrading methylene blue by comparison to its rutile phase.     

Axially symmetric electrovac solutions

Two classes of electrovac solutions are obtained in oblate spheroidal coordinates, which are the electromagnetic analogs of Zipoy's monopole and dipole solutions. The asymptotic behavior of the solutions is studied to gain some insight into the nature of the source of the gravitational and electromagnetic fields. A similar stationary solution of the pure gravitational field is found to belong to Papapetrou's class.     

Growth of hair and the trace element profile a study by sectional analysis

Correlations between the growth of hair and the trace element profile have been investigated by non-destructive neuron activation analysis through gamma-ray speetrometry using NaI(Tl) as well as Ge(Li) detectors. After preliminary investigations to establish the experimental errors, the effect of washing procedures and in-person variations, hair samples belonging to ladies with known case histories, particularly with regard to dietary habits, health and profession, were examined. Scalp-hair samplex 50–100 cm in length, representing an average time span of ∼5–10 years were collected by combing. Samples in their non-anagen phase, differentiated by their roots, were analysed in 10 cm sections. The concentrations of the following elements were determined: Na, Cl, Mn, Co, Cu, Zn, As, Se, Ag, I, Au and Hg. Absolute values for the concentrations are reported for most of the elements, while for the rest relative values for the various sections are given. The values for the different sections vary by large factors for many elements although for some elements, like Cu and Mn, the variations are not appreciable. The unusually large concentrations of elements like Se ang Hg are in broad agreement with the case histories. However, detailed examination of the results with regard to time-dependent variations seem to pose serious problems in the applications to forensic science.