Structure in the E2 quasicontinuum spectrum of Dy154

The evolution of the quasicontinuum spectrum with neutron number has been investigated in the sequence of isotopes Dy152,154,156. The three nuclei display a pronounced collective E2 component. In Dy154 this component shows a splitting into two distinct parts, signifying a structural change along the cascade above the yrast line. The E2 and statistical components are reproduced in simple -cascade calculations; in Dy152 and Dy156 only rotational bands are included, whereas in Dy154 additional vibration-like transitions are required to reproduce the two E2 peaks

Structural changes along and above the yrast line of Dy154

States in Dy154 have been located up to I=48+ and their lifetimes measured. Marked structural changes occur along the yrast line with a transition from prolate to oblate shape, followed by an unexpected return to moderate collectivity at the highest spins. Structural changes with increasing energy above the yrast line are also observed

Lifetime measurements of terminating and collective high-spin states in 155DY^{155}DY and 156DY^{156}DY

Lifetime measurements for the isotopes 155Dy and 156Dy have been extended up to spins around 40h{stroke} by the Doppler shift attenuation method in conjunction with γ-γ-coincidence measurements. Results have been obtained for the yrast band in 156Dy and for three bands in 155Dy. Strong retardations of the E2-strengt were observed for intruding terminating sequences, for which specific single particle configurations are suggested

Microwave-assisted synthesis, anticonvulsant activity and quantum mechanical modelling of N-(4-bromo-3-methylphenyl) semicarbazones

Objective: To study the effect of halo substitution on disubstituted aryl semicarbazones on the anticonvulsant potential and model the activity based on quantum mechanics. Methods: A series of twenty-six compounds of N(4)-(4-bromo-3-methylphenyl) semicarbazones were synthesized and evaluated for the anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. Some potential compounds were also tested in the subcutaneous strychnine (scSTY) and subcutaneous picrotoxin (scPIC) seizure threshold tests. The synthesized compounds were tested for behavioral impairment and CNS (central nervous system) depression in mice. Quantum mechanical modelling was carried out on these compounds to gain understanding on the structural features essential for activity. Results: Some compounds possessed broad spectrum anticonvulsant activity as indicated by their effect in pentylenetetrazole, strychnine, picrotoxin and maximal electroshock seizures models in resemblance to other aryl semicarbazone derivatives reported earlier. The higher the difference in HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energy levels was, the greater was the activity profile. Conclusion: The pharmacophoric requirements for compounds to exhibit anticonvulsant activity that includes one aryl unit in proximity to a hydrogen donor-acceptor domain and an electron donor have been justified with the molecular orbital surface analysis of the synthesized compounds