[en] A sequence of amyloid precursor protein (APP) cleavages culminates in the sequential release of the APP intracellular domain (AICD) and the amyloid β peptide (Aβ) and/or p3 fragment. One of the environmental factors favouring the accumulation of AICD appears to be a rise in intracellular pH. Here we further identified the metabolism and subcellular localization of artificially expressed constructs under such conditions. We also co-examined the mechanistic lead up to the AICD accumulation and explored possible significances for its increased expression. We found that most of the AICD generated under pH neutralized conditions is likely cleaved from C83. While the AICD surplus was unable to further activate transcription of a luciferase reporter via a Gal4-DNA-binding domain, it failed entirely via the endogenous promoter regions of proposed target genes, APP and KAI1. The lack of a specific transactivation potential was also demonstrated by the unchanged levels of target gene mRNA. However, rather than translocating to the nucleus, the AICD surplus remains membrane tethered or free in the cytosol where it interacts with Fe65. Therefore we provide strong evidence that an increase in AICD generation does not directly promote gene activation of previously proposed target genes

[en] An island of isomers have recently been observed on both sides of the N=40 shell below the Ni isotopes. Isomeric states in the 65Fe and 67Fe allow the knowledge of the single particle structure around the νg9/2 shell. Moreover, the excitation energy of the first 2+ and 4+ states in the 68Fe have been established by β-γ correlation. The evolution of the structure of the Fe isotopes going far away from the valley of stability is, for the first time, given for N>40

[en] Published in summary form only

[en] Large-scale shell-model calculations have been performed to calculate the negative-parity states of even-odd ^61-65Fe isotopes. The results are compared with the recent experimental data reported at Legnaro National Laboratories and also with earlier calculations with fpg interaction in a truncated configuration space. It is observed that negative parity states of ⁶¹Fe can be well reproduced with GXPF1A interaction in full fp space without truncation. For ⁶³Fe the correct ordering of levels is not reproduced. The structure of the wave function for the ground state and first excited state suggests that the ordering of the single-particle energy levels gets modified due to monopole correction.

[en] The low energy structure of ⁶⁶Fe was studied by means of γ- and fast-timing spectroscopy at the ISOLDE/CERN facility. The level scheme of ⁶⁶Fe populated following the ${\mathrm{\beta <!--\; ??\; -->}}^{-<!--\; ???\; -->}$ decay of ⁶⁶Mn was established. It confirms and further expands the level scheme from recent publications. The β-delayed neutron emission branch was measured and γ rays in ⁶⁵Fe were observed following the β–n decay for the first time. The half lives of the $2_1^{+}$ state and four other states of ⁶⁶Fe were measured using the advanced time-delayed $\mathrm{\beta <!--\; ??\; -->}\mathrm{\gamma <!--\; ??\; -->}\mathrm{\gamma <!--\; ??\; -->}$(t) method. These results are compared with large-scale shell-model calculations based on the Lenzi–Nowacki–Poves–Sieja interaction. The β-decay of ⁶⁶Mn to ⁶⁶Fe has been calculated as well, and log(ft) values derived. Spin and parity assignments are proposed based on the experimental information and the new calculations. (paper)

[en] Neutron-rich Co and Fe isotopes produced by ⁸⁶Kr projectile fragmentation at 500 MeV/u have been separated and identified using the Fragment Separator (FRS) in a bunched energy mode. ⁶⁶Co and ⁶⁵Fe ions were selectively implanted in a double PIN-diode array where the β-decay signals were measured. The half-lives were deduced from time correlations between implantation and β-decay signals. The re-measurement of the ⁶⁶Co half-life confirms the isotope identification. The value of ⁶⁵Fe half-life was found to be 0.45±0.15 s. (authors). 18 refs., 5 figs

[en] The low-energy beam and ion trap facility LEBIT at NSCL/MSU is at present the only facility where precision experiments are performed with stopped rare isotope beams produced by fast-beam fragmentation. LEBIT combines high-pressure-gas stopping with advanced ion manipulation techniques to provide brilliant low-energy beams. So far these beams have mainly been used for mass measurements on short-lived rare isotopes with a 9.4 T Penning trap mass spectrometer. Recent examples include ^70mBr, located at the proton dripline, ³²Si and the iron isotopes ^63-65Fe. While the measurement of ³²Si helps to solve a long-standing dispute over the validity of the isobaric multiplet mass equation (IMME) for the A=32, T=2 multiplet, the mass measurements of ^65m,g Fe marked the first time a nuclear isomeric state has been discovered by Penning trap mass spectrometry. (orig.)

[en] We investigate the effects of single-particle structure and pairing on the equilibration of positive and negative-parity level densities for the even-even nuclei ^58,62,66Fe and ⁵⁸Ni and the odd-A nuclei ⁵⁹Ni and ⁶⁵Fe. Calculations are performed using the shell model Monte Carlo method in the complete fp-gds shell-model space using a pairing+quadrupole type residual interaction. We find for the even-even nuclei that the positive-parity states dominate at low excitation energies due to strong pairing correlations. At excitation energies at which pairs are broken, single-particle structure of these nuclei is seen to play the decisive role for the energy dependence of the ratio of negative-to-positive parity level densities. We also find that equilibration energies are noticeably lower for the odd-A nuclei ⁵⁹Ni and ⁶⁵Fe than for the neighboring even-even nuclei ⁵⁸Ni and ⁶⁶Fe.

[en] A new long-lived isomeric state in ⁶⁵Fe has been discovered with Penning trap mass spectrometry and high-precision mass measurements of the neutron-rich isotopes ^63-65Fe and ^64-66Co have been performed with the Low-Energy Beam and Ion Trap Facility at the NSCL. For the new isomer in ⁶⁵Fe an excitation energy of 402(5) keV has been determined from the measured mass difference between the isomeric and ground states. The mass uncertainties of all isotopes have been reduced by a factor of 10-100 compared to previous results. In the case of ⁶⁴Co the previous mass value was found to deviate by about 5 standard deviations from the new measurement

[en] The Low Energy Beam and Ion Trap (LEBIT) is the only present facility to combine high precision Penning trap mass spectrometry with fast beam projectile fragmentation. Located at the National Superconducting Cyclotron Laboratory (NSCL), LEBIT is able to measure radionuclides produced in a chemically independent process with minimal decay losses. Recent exotic mass measurements include ⁶⁶As, ^63-66Fe, and ³²Si. ⁶⁶As is a new candidate to test the Conserved Vector Current (CVC) hypothesis. The masses of the neutron-rich iron isotopes provide additional information about the mass surface and the subshell closure at N = 40. ³²Si is a member of the A = 32, T = 2 quintet; its measurement permits the most stringent test of the validity of the isobaric multiplet mass equation (IMME). An overview of some recent measurements will be presented as well as advanced techniques for ion manipulation.