Radioactive decay of Eu154

The radioactive decay of Eu¹⁵⁴ (t _1/2=16y), obtained from thermal neutron irradiations of 95% enriched Eu¹⁵³, has been studied by using the Seigbahn-Slätis intermediate image spectrometer, a thin lens magnetic spectrometer and a coincidence scintillation spectrometer. The following gamma-rays (energy in kev.) have been identified as belonging to this isotope: 123, 248, 585, 717, 759, 875, 998, 1007, 1285, 1600. Beta end points of Eu¹⁵⁴ were measured at 275 (20%), 590 (45%), 890 (23%) and 1860 (12%). The K-conversion coefficient of 123 kev. gamma-ray has been experimentally determined to be ～0·5. On the basis of gamma-gamma and beta-gamma coincidences, the decay scheme of Eu¹⁵⁴ has been deduced: the resulting level-structure of Gd¹⁵⁴ conforms well with the predictions of the unified nuclear model.     

Microstructural and magnetic characterization of fly ash from Kolaghat Thermal Power Plant in West Bengal, India

This paper reports on the physical nature of the fly ash sample of the Kolaghat Thermal Power Plant, India with an emphasis on its ultrafine nature. This paper also deals with the measurement of the magnetic properties of the fine particles of the fly ash sample. Particle sizes of this fly ash sample estimated from the SEM images lie within 0.16-5.50 μm, and the EDX spectral analysis indicates the presence of O, Al, Si, C, Fe, Mg, Na, K and Ti in this sample. From the XRD study, it is found that physical nature of conglomeration in the fly ash is crystalline and the major components are mullite (Al₆Si₂O₁₃) and quartz (SiO₂). Additionally, the presence of hematite, microcline, magnetite, maghemite and free iron in smaller fractions cannot be ruled out. A large magnetization observed at 5 K indicates the presence of magnetic components possibly due to superparamagnetism owing to very fine magnetic particles present. The hyperfine parameters obtained from the ⁵⁷Fe Mössbauer spectroscopy, in general, support the observations made from the XRD analysis and in particular, provides the quantitative estimation of the different iron ions present in the sample. Precisely, this report presents experimental data on physical aspects of the fly ash sample of a thermal power plant which consists of coarse, fine and ultrafine magnetic particulate materials (PMs) and deals with an in-depth analysis of it.     

Synthesis of Linoleic Acid Capped Copper Nanoparticles and Their Fluorescence Study

Copper nanoparticles have been prepared through the reduction of cupric ions by ethanol with linoleic acid as a capping agent. The morphology and structure of these nanoparticles have been investigated using transmission electron microscopy. The X-diffraction study shows that the nanoparticles are crystalline and mainly composed of face-centered cubic (fcc) copper with a narrow size distribution having an average size of 5 nm. Fluorescence spectra of these copper nanoparticles have been analysed which show two emission peak at 450 nm and 625 nm corresponding to the large energy band and small energy band respectively, when illuminated at 250 nm of an optical source.     

Lindstedt Poincare technique applied to molecular potentials

The Lindstedt–Poincare technique has traditionally been used to deal with oscillators with power-law potentials. We show how this method can be extended to deal with molecular potentials for which the frequency goes to zero as the energy approaches zero. The extension requires the use of an asymptotic analysis which is combined with perturbation theory. For the Morse potential, we get an exact answer while for the Lennard Jones class of potentials \({{\rm V}={\rm V}_0 \left[ {\left( {\frac{{a}}{{\rm x}}}\right)^{2{\rm n}}-\left({\frac{{\rm a}}{{\rm x}}}\right)^{{\rm n}}}\right]}\) , the answer is generally approximate with some values of n giving exact results. For the widely studied case, n=6, our approximation gives better than 1% accuracy at the lowest order of calculation. We show that as \({{\rm n} \rightarrow \infty}\) , the result tends to that for the Morse potential. We also point out that the time period obtained by us can be used to obtain the quantum mechanical energy levels of these potentials within the Bohr-Sommerfeld scheme.     

Bohr Sommerfeld quantisation and molecular potentials

We combine, within the Bohr Sommerfeld quantization rule, a systematic perturbation with asymptotic analysis of the action integral for potentials which support a finite number of bound states with E < 0 to obtain an interpolation formula for the energy eigenvalues. We find interpolation formulae for the Morse potential as well as potentials of the form \({V=V_0 \left[ {\left( {\frac{a}{x}} \right)^{2k}-\left( {\frac{a}{x}}\right)^{k}} \right]}\). For k = 6 i.e. the well known Lennard Jones potential this yields results within 1 per cent of the highly accurate numerical values. For the Morse potential this procedure yields the exact answer. We find that the result for the Morse potential which approaches zero exponentially is the \({k\rightarrow\infty}\) limit of the Lennard Jones class of potentials.     

A systematic evaluation of the role of crystalline order in nanoporous materials on DNA separation

The role of order within a porous separation matrix on the separation efficiency of DNA was studied systematically. DNA separation was based on a ratchet mechanism. Monodisperse colloidal suspensions of nanoparticles were used to fabricate highly ordered separation media with a hexagonal close-packed structure. Doping with a second particle size yielded structures with different degrees of disorder, depending upon the volume fraction of each particle size. Radial distribution functions and orientational order parameters were calculated from electron micrographs to characterize the scale of disorder. The peak separation distance, band broadening, and separation resolution of DNA molecules was quantified for each structure. DNA separation parameters using pulsed fields and the ratchet effect showed a strong dependence on order within the porous nanoparticle array. Ordered structures gave large separation distances, smaller band broadening and better resolution than highly disordered, nearly random, porous structures. The effect dominated these three parameters when compared to the effect of pore size. However, the effect of order on separation performance was not monotonic. A small, but statistically significant improvement was seen in structures with short range order compared to those with long range order.     

p-embeddings

This is the sequel to Bhattacharjee et al. (in press) [3] where the notion of a p  -extension of commutative rings was investigated: a unital extension of commutative rings, say R?S$R?S$, is a p  -extension if for every s∈S$s\in S$ there is an r∈R$r\in R$ such that rS=sS$rS=sS$. In this article we apply the theory of p  -extensions to rings of continuous functions. We show that this concept lays between the concepts of C^?$C^{?}$-embeddings and z-embeddings.     

Mechanistic and kinetics study of the gas phase reactions of methyltrifluoroacetate with OH radical and Cl atom

Theoretical investigations are carried out on the title reactions by means of ab initio and DFT methods. The optimized geometries, frequencies and minimum energy path are obtained at MPWB1K/6-31+G(d,p) level. Single point energy calculations are performed at MP2 and QCISD(T) levels of theory. Energetics were further refined by calculating the energy of the species with a high level G2(MP2) method. The rate constant of the two reactions are calculated at 298?K and 1?atm using Canonical Transition State Theory (CTST) utilizing the ab initio data obtained during the present study. The rate constant values are found to be 5.5?×?10^?14 and 5.9?×?10^?14?cm³ molecule^?1 s^?1, respectively which are in good agreement with the experimental data.     

Crystal structure of the potent bisquinoline antimalarial agent (±)-trans-N 1,N 2-bis(7-chloroquinolin-4-yl) cyclohexane-1,2-diamine dimethanesulfonate salt hydrate in relation to its biological properties

The neighboring 4-aminoquinoline substituents of the bisquinoline (±)-trans-N ¹,N ²-bis(7-chloroquinolin-4-yl)cyclohexane-1,2-diamine dimethanesulfonate salt crystallized in the diequatorial position which is in agreement with quantum chemical calculations. The bisquinoline salt crystallized in the monoclinic C2/c space group with a = 19.328(4) Å, b = 15.618(3) Å, c = 20.382(4) Å, = 98.84(3)°. The two quinoline nitrogen atoms are protonated by the salt as predicted by calculated electrostatic surface potentials. The –5 kcal/mol isopotential surface of the bisquinoline resembles that of chloroquine, which may explain the potent inhibition of hematin polymerization by both the bisquinoline and chloroquine. The smaller HOMO/LUMO gap of the bisquinoline is consistent with its phototoxicity. The overall conformation, the ability of all nitrogen atoms to participate in hydrogen bonding, and the electrostatic interaction of the quinoline rings in the crystal packing may all aid in the determination of the binding pharmacophore of the bisquinoline.