Abstract: As swipe samples from enrichment activities typically contain uranium particles with a detectable amount of fluorine, the question was raised whether the analysis of fluorine in particles could complement the information on the uranium isotope ratios. For this, uranium oxyfluoride particles were prepared from the controlled hydrolysis of uranium hexafluoride (UF6). The relative amount of fluorine was characterized by scanning electron microscopy combined with energy-dispersive X-ray spectrometry (SEM-EDX), as well as ion-microprobe secondary ion mass spectrometry (IM-SIMS). Of particular interest was the assessment of the reduction of the amount of fluorine over time, and after exposure to UV-light and high temperatures. Micro-Raman spectrometry (MRS) was applied to look for differences in molecular structure between these various sample types. Both SEM-EDX and IM-SIMS showed a general reduction of the fluorine-to-uranium ratio after 12 years of storage. The exposure to UV-light and high temperatures was found to have accelerated the loss of fluorine. A distinct peak at 865 cm− 1 Raman shift was detected for the majority of particles analyzed by MRS. For the particles that were heat-treated, the Raman spectra were similar to the spectrum of U3O8. Although often large variations were observed between particles from the same sample, the three particle measurement techniques (IM-SIMS, SEM-EDX and MRS) showed some consistent trends. They therefore appear promising in terms of the ability to place bounds on particle age, as well as shedding light on the complex processes involved in UO2F2 particle ageing.

Abstract: Lanthanum carbonate is a new phosphate binder that is poorly absorbed from the gastrointestinal tract and eliminated largely by the liver. After oral treatment, we and others had noticed 23 fold higher lanthanum levels in the livers of rats with chronic renal failure compared to rats with normal renal function. Here we studied the kinetics and tissue distribution, absorption, and subcellular localization of lanthanum in the liver using transmission electron microscopy, electron energy loss spectrometry, and X-ray fluoresence. We found that in the liver lanthanum was located in lysosomes and in the biliary canal but not in any other cellular organelles. This suggests that lanthanum is transported and eliminated by the liver via a transcellular, endosomal-lysosomal-biliary canicular transport route. Feeding rats with chronic renal failure orally with lanthanum resulted in a doubling of the liver levels compared to rats with normal renal function, but the serum levels were similar in both animal groups. These levels plateaued after 6 weeks at a concentration below 3 g/g in both groups. When lanthanum was administered intravenously, thereby bypassing the gastrointestinal tract-portal vein pathway, no difference in liver levels was found between rats with and without renal failure. This suggests that there is an increased gastrointestinal permeability or absorption of oral lanthanum in uremia. Lanthanum levels in the brain and heart fluctuated near its detection limit with long-term treatment (20 weeks) having no effect on organ weight, liver enzyme activities, or liver histology. We suggest that the kinetics of lanthanum in the liver are consistent with a transcellular transport pathway, with higher levels in the liver of uremic rats due to higher intestinal absorption.

Abstract: We introduce a differential geometry description of the path lines, stream lines and particles contours in hydrodynamics. We present a generalized form of a Korteweg-de Vries type of equation for the exterior of a circle. Nonlinearities from the boundary conditions, surface tension and the Euler equations are taken into account, but the flow is considered inviscid and irrotational. For the circular case we describe the traveling waves shapes, solitons and the particles trajectories.

Abstract: Merged, or giant, multi-quanta vortices (GVs) appear in very small superconductors near the superconducting transition due to strong confinement of magnetic flux. Here we present evidence for a new, pinning-related, mechanism for vortex merger. Using Bitter decoration to visualise vortices in small Nb disks, we show that confinement in combination with strong disorder causes individual vortices to merge into clusters/GVs well below Tc and Hc2, in contrast to well-defined shells of individual vortices found in the absence of pinning.

Abstract: Experimentally, multivortex states and giant vortex states in mesoscopic superconductors can be distinguished directly by using the multiple-small-tunnel-junctions, and indirectly by studying the temperature dependence of the expulsion fields. These experimental results are compared with the theoretical prediction from the nonlinear Ginzburg- Landau theory.