High-temperature weak ferromagnetism on the verge of a metallic state: Impact of dilute Sr-doping on BaIrO3

The 5d-electron based BaIrO3 is a nonmetallic weak ferromagnet with a Curie temperature at Tc=175 K. Its largely extended orbitals generate strong electron-lattice coupling, and magnetism and electronic structure are thus critically linked to the lattice degree of freedom. Here we report results of our transport and magnetic study on slightly Sr doped BaIrO3. It is found that dilute Sr-doping drastically suppresses Tc, and instantaneously leads to a nonmetal-metal transition at high temperatures. All results highlight the instability of the ground state and the subtle relation between magnetic ordering and electron mobility. It is clear that BaIrO3 along with very few other systems represents a class of materials where the magnetic and transport properties can effectively be tuned by slight alterations in lattice parameters

Level Lifetimes and the Structure of \u3csup\u3e134\u3c/sup\u3eXe from Inelastic Neutron Scattering

The level structure of 134Xe was studied with the inelastic neutron scattering reaction followed by γ-ray detection. A number of level lifetimes were determined for the first time with the Doppler-shift attenuation method and the low-lying excited states were characterized. From this new spectroscopic information, the third excited state, a 0+ level which had only been observed in a previous inelastic neutron scattering study, was verified. Reduced transition probabilities were calculated; comparisons were drawn with a vibrational description of the nucleus and found lacking. The 3− octupole phonon has been confirmed, and the complete negative-parity multiplet resulting from the ν(1h11/22d3/2) configuration has also been tentatively identified for the first time in the N = 80 isotones

[89Zr]Oxinate4 for long-term in vivo cell tracking by positron emission tomography

Purpose 111In (typically as [111In]oxinate3) is a gold standard radiolabel for cell tracking in humans by scintigraphy. A long half-life positron-emitting radiolabel to serve the same purpose using positron emission tomography (PET) has long been sought. We aimed to develop an 89Zr PET tracer for cell labelling and compare it with [111In]oxinate3 single photon emission computed tomography (SPECT). Methods [89Zr]Oxinate4 was synthesised and its uptake and efflux were measured in vitro in three cell lines and in human leukocytes. The in vivo biodistribution of eGFP-5T33 murine myeloma cells labelled using [89Zr]oxinate4 or [111In]oxinate3 was monitored for up to 14 days. 89Zr retention by living radiolabelled eGFP-positive cells in vivo was monitored by FACS sorting of liver, spleen and bone marrow cells followed by gamma counting. Results Zr labelling was effective in all cell types with yields comparable with 111In labelling. Retention of 89Zr in cells in vitro after 24 h was significantly better (range 71 to >90 %) than 111In (43–52 %). eGFP-5T33 cells in vivo showed the same early biodistribution whether labelled with 111In or 89Zr (initial pulmonary accumulation followed by migration to liver, spleen and bone marrow), but later translocation of radioactivity to kidneys was much greater for 111In. In liver, spleen and bone marrow at least 92 % of 89Zr remained associated with eGFP-positive cells after 7 days in vivo. Conclusion [89Zr]Oxinate4 offers a potential solution to the emerging need for a long half-life PET tracer for cell tracking in vivo and deserves further evaluation of its effects on survival and behaviour of different cell types

Field-tuned Collapse of an Orbital Ordered and Spin-polarized State: Colossal Magnetoresistance in Bilayered Ruthenate

Ca3Ru2O7 with a Mott-like transition at 48 K features different in-plane anisotropies of magnetization and magnetoresistance. Applying magnetic field along the magnetic easy-axis precipitates a spin-polarized state via a first-order metamagnetic transition, but does not lead to a full suppression of the Mott state, whereas applying magnetic field along the magnetic hard axis does, causing a resistivity reduction of three orders of magnitude. The colossal magnetoresistivity is attributed to the collapse of the orbital ordered and spin-polarized state. Evidence for a density wave is also presented.Comment: 10 pages plus 4 figure

PET Cell Tracking Using 18F-FLT is Not Limited by Local Reuptake of Free Radiotracer

Assessing the retention of cell therapies following implantation is vital and often achieved by labelling cells with 2'-[(18)F]-fluoro-2'-deoxy-D-glucose ((18)F-FDG). However, this approach is limited by local retention of cell-effluxed radiotracer. Here, in a preclinical model of critical limb ischemia, we assessed a novel method of cell tracking using 3'-deoxy-3'-L-[(18)F]-fluorothymidine ((18)F-FLT); a clinically available radiotracer which we hypothesise will result in minimal local radiotracer reuptake and allow a more accurate estimation of cell retention. Human endothelial cells (HUVECs) were incubated with (18)F-FDG or (18)F-FLT and cell characteristics were evaluated. Dynamic positron emission tomography (PET) images were acquired post-injection of free (18)F-FDG/(18)F-FLT or (18)F-FDG/(18)F-FLT-labelled HUVECs, following the surgical induction of mouse hind-limb ischemia. In vitro, radiotracer incorporation and efflux was similar with no effect on cell viability, function or proliferation under optimised conditions (5 MBq/mL, 60 min). Injection of free radiotracer demonstrated a faster clearance of (18)F-FLT from the injection site vs. (18)F-FDG (p ≤ 0.001), indicating local cellular uptake. Using (18)F-FLT-labelling, estimation of HUVEC retention within the engraftment site 4 hr post-administration was 24.5 ± 3.2%. PET cell tracking using (18)F-FLT labelling is an improved approach vs. (18)F-FDG as it is not susceptible to local host cell reuptake, resulting in a more accurate estimation of cell retention

Behavior and modeling of tessellated shear walls in a structural frame system

This paper studies the behavior of a reinforced concrete (RC) structural frame employing a tessellated structural-architectural (TeSA) shear wall as the lateral-load resisting element. TeSA walls are made of interlocking modules (tiles) that provide easier repairability and replaceability. A nonlinear finite element model of a TeSA wall with tiles interlocking in one direction (1-D interlocking) is validated using test data. An RC frame from a building is modeled with a 1-D interlocking TeSA shear wall. The effects of varying rigidity of the wall-frame connections (rigid, hinged, slotted) on the lateral strength of the system and the axial load demands of the gravity-load resisting systems are evaluated. Finally, the effect of connection details on the damage of the TeSA wall is also studied. The study shows that the lateral strength of the system is the highest with a rigid connection between the wall and the system, followed by the system with hinged connections. Slotted connections, which provided no vertical coupling between the wall and the frame result in the lowest lateral strength. TeSA wall experienced “slight damage” up to a drift ratio of 2%. The system with rigid connections between the wall and the frame experienced the most damage, followed by system with hinged and slotted connections

Status of vibrational structure in Ni62

Measurements consisting of γ-ray excitation functions and angular distributions were performed using the (n,n′γ) reaction on Ni62. The excitation function data allowed us to check the consistency of the placement of transitions in the level scheme. From γ-ray angular distributions, the lifetimes of levels up to ~3.8 MeV in excitation energy were extracted with the Doppler-shift attenuation method. The experimentally deduced values of reduced transition probabilities were compared with the predictions of the quadrupole vibrator model and with large-scale shell model calculations in the fp shell configuration space. Two-phonon states were found to exist with some notable deviation from the predictions of the quadrupole vibrator model, but no evidence for the existence of three-phonon states could be established. Z=28 proton core excitations played a major role in understanding the observed structure. © 2011 American Physical Society