First evidence for triaxial superdeformation in 161Lu and 162Lu

High-spin states in ¹⁶¹Lu and ¹⁶²Lu have been investigated using the GASP γ-ray spectrometer array. Excited states in these nuclei have been populated through the ¹⁰⁰Mo(⁶⁵Cu, xn) reaction at a beam energy of 260 MeV. Four presumably triaxial superdeformed bands, three in ¹⁶²Lu and one in ¹⁶¹Lu, have been observed. This is the first evidence for triaxial superdeformation in the two isotopes. Received: 18 October 2002 / Accepted: 21 November 2002 / Published online: 4 February 2003 RID="a" ID="a"e-mail: bringel@iskp.uni-bonn.de RID="b" ID="b"Present address: Wright Nuclear Structure Laboratory, Yale University, New Haven, CT 06520, USA. RID="c" ID="c"Present address: Physik Department, Technische Universit?t München, James Franck Str., D-85748 Garching, Germany. Communicated by D. Schwalm     

Levels in doubly odd 138Pr

The band structures of the doubly odd ¹³⁸Pr nucleus have been investigated using the ¹²⁸Te(¹⁴N, 4n)¹³⁸Pr reaction at a beam energy of 55-65 MeV. Altogether six distinct structures have been established, of which the lower part of the yrast band and two side bands were known from earlier works. The observed level properties of the members of the yrast band have been compared with theoretical calculations performed within the Particle Rotor Model (PRM) with axially symmetric core. The experimental branching ratios and B(M1)/B(E2) values when compared with the theoretical results of the PRM, suggest an oblate core.     

Rotational bands in the near-drip-line nucleus 128Nd

The even-even nucleus ¹²⁸Nd was studied via in-beam γ-ray spectroscopy using the ⁴⁰Ca + ⁸²Mo reaction at 190 MeV. Two new bands were observed besides the yrast one, that has been extended up to spin 34⁺. Configurations were assigned to the three bands by analysing their rotational properties and by comparison with the neighboring even-even nuclei. Received: 18 July 2001 / Accepted: 25 October 2001     

Nuclear structure explored by β-delayed decay spectroscopy of spin-polarized radioactive nuclei at TRIUMF ISAC-1

Spin-polarized radioactive nuclear beams at TRIUMF enable a new spectroscopic method which efficiently assigns spins and parities of the daughter levels by taking advantage of the asymmetric β-decay of the polarized parent nucleus. This method was successfully applied to structure studies of ²⁹Mg and ³⁰Mg in connection with the physics of the “island of inversion”. In ²⁹Mg, two low-lying levels with intruder configuration were assigned. In ³⁰Mg, coexistence of spherical shape, prolate shape and γ-collectivity was strongly suggested.     

CONCERNING THE ORIGIN OF CHARGE AT THE POLYSTYRENE PARTICLE/WATER INTERFACE

The electrophoretic mobility behavior of well-characterized polystyrene latex particles, carrying one type of surface functional endgroups, has been studied as a function of pH. At low pH, the interaction of protons with the functional endgroups increased in the order: Hydroxyl > carboxyl > sulfate; at high pH the order of interaction was reversed; and at intermediate pH no interactions were observed. The particles of the polystyrene latexes in their different forms at the intermediate pH range, dispersed in deionized water, all exhibited the same mobility irrespective of the functional endgroup. The origin of charge in these systems is explained as being the result of either the preferential adsorption of hydroxyl ions or an electron - injection mechanism due to the overlap of local intrinsic molecular - ion states in polystyrene and water. At low concentrations of functional endgroups, the surface properties of the polystyrene latexes are largely dependent upon the hydrophobic nature of the surface.     

High spin states in the nucleus150Tb

Excited states in the nucleus¹⁵⁰Tb have been investigated up to spin 39? and 13 MeV excitation energy using the¹³⁰Te(²⁷Al, 7n) reaction and the EUROGAM array. The theoretical interpretation of the observed states has been performed in the framework of the deformed independent particle model. The analysis of the decay out of the yrast superdeformed band indicates that normal-deformed states with spins between 24? and 28? are fed.     

Both systemic and local application of Granulocyte-colony stimulating factor (G-CSF) is neuroprotective after retinal ganglion cell axotomy

Background  

The hematopoietic Granulocyte-Colony Stimulating Factor (G-CSF) plays a crucial role in controlling the number of neutrophil progenitor cells. Its function is mediated via the G-CSF receptor, which was recently found to be expressed also in the central nervous system. In addition, G-CSF provided neuroprotection in models of neuronal cell death. Here we used the retinal ganglion cell (RGC) axotomy model to compare effects of local and systemic application of neuroprotective molecules.     

Packing and viscoelasticity of polyunsaturated omega-3 and omega-6 lipid bilayers as seen by (2)H NMR and X-ray diffraction

Polyunsaturated phospholipids of the omega-3 and omega-6 classes play key roles in cellular functions, yet their mechanisms of biological action are still a matter of debate. Using deuterium ((2)H) NMR spectroscopy and small-angle X-ray diffraction, we show how membrane properties are modified by docosahexaenoic (DHA; 22:6) and arachidonic (AA; 20:4) acyl chains of the omega-3 and the omega-6 families, respectively. Structural and dynamical differences due to polyunsaturation are evident in both the ordered and disordered phases of mixed-chain (16:0)(22:6)PC and (16:0)(20:4)PC bilayers. Due to the lower chain melting temperature, the omega-6 AA bilayer is more disordered in the fluid (L(alpha)) state than the omega-3 DHA bilayer; it is thinner with a larger area per lipid. The thermal hysteresis observed for the DHA bilayer may represent the influences of angle-iron conformers in the gel state and back-bended, hairpinlike conformers in the fluid state, consistent with molecular dynamics studies. Interpretation of the (2)H NMR order profiles of (16:0-d(31))(22:6)PC and (16:0-d(31))(20:4)PC together with X-ray electron density profiles reveals an uneven distribution of mass; i.e., the sn-1 saturated chain is displaced toward the membrane center, whereas the sn-2 polyunsaturated chain is shifted toward the bilayer aqueous interface. Moreover, the (2)H NMR relaxation rates are increased by the presence of omega-6 AA chains compared to omega-3 DHA chains. When evaluated at the same amplitude of motion, relaxation parameters give a naturally calibrated scale for comparison of fluid lipid bilayers. Within this framework, polyunsaturated bilayers are relatively soft to bending and area fluctuations on the mesoscale approaching molecular dimensions. Significant differences are evident in the viscoelastic properties of the omega-3 and omega-6 bilayers, a possibly biologically relevant feature that distinguishes between the two phospholipid classes.