Demand driven salt clean-up in a molten salt fast reactor - Defining a priority list.

The PUREX technology based on aqueous processes is currently the leading reprocessing technology in nuclear energy systems. It seems to be the most developed and established process for light water reactor fuel and the use of solid fuel. However, demand driven development of the nuclear system opens the way to liquid fuelled reactors, and disruptive technology development through the application of an integrated fuel cycle with a direct link to reactor operation. The possibilities of this new concept for innovative reprocessing technology development are analysed, the boundary conditions are discussed, and the economic as well as the neutron physical optimization parameters of the process are elucidated. Reactor physical knowledge of the influence of different elements on the neutron economy of the reactor is required. Using an innovative study approach, an element priority list for the salt clean-up is developed, which indicates that separation of Neodymium and Caesium is desirable, as they contribute almost 50% to the loss of criticality. Separating Zirconium and Samarium in addition from the fuel salt would remove nearly 80% of the loss of criticality due to fission products. The theoretical study is followed by a qualitative discussion of the different, demand driven optimization strategies which could satisfy the conflicting interests of sustainable reactor operation, efficient chemical processing for the salt clean-up, and the related economic as well as chemical engineering consequences. A new, innovative approach of balancing the throughput through salt processing based on a low number of separation process steps is developed. Next steps for the development of an economically viable salt clean-up process are identified.

[Special care units for the treatment of acutely ill, cognitively impaired geriatric patients in Germany]. / Spezialisierte Stationen zur Behandlung von akut erkrankten geriatrischen Patienten mit zusätzlichen kognitiven Beeinträchtigungen in Deutschland.

During recent years, specialized wards have been established in geriatric hospital departments as a consequence of the growing need of special care for acutely ill older patients, who are also cognitively impaired. However, there are neither established standards nor any commonly agreed concept of care. A written survey among 12 specialized wards in Germany revealed some characteristics of these wards: extended geriatric assessment, special education of staff including validation and gerontopsychiatric issues, and particular equipment/architecture, such as hidden doors and group rooms, and in some cases loop tracks for walking, therapeutic facilities, and 'living rooms' on the wards. There is a wide variability with respect to the designation of these wards, the number of beds, length of stay, and admission criteria. It appears from this survey that there should be an exchange of empirical experience made on these wards, and there is a need of collaborative research on its usefulness.

A fatigue life analysis of small fragment screws.

OBJECTIVES: To conduct a comparative fatigue analysis of several commonly used small fragment screws. DESIGN: Biomechanical laboratory study. SETTING: Research laboratory. MAIN OUTCOME MEASUREMENTS: A fatigue life analysis of seven different types of small fragment screws was conducted using a Wohler fatigue-testing machine. Four different types of 3.5-millimeter cortical screws were subjected to fatigue analysis. These included solid stainless steel screws from Synthes Ltd. (core diameter 2.4 millimeters), Zimmer Inc. (core diameter 2.4 millimeter), and Smith and Nephew Richards Inc. (core diameter 2.4 millimeters) and cannulated stainless steel screws from Synthes Ltd. (core diameter 2.5 millimeters). In addition, three types of 4.0-millimeter cancellous screws were tested. These included stainless steel screws from Synthes Ltd. (core diameter 1.9 millimeters), titanium screws from Synthes Ltd. (core diameter 2.0 millimeters), and titanium alloy screws from DePuy-Ace (core diameter 2.8 millimeters). Fatigue lives, as reflected by mean cycles to failure, were compared. RESULTS: The four types of cortical screws had longer fatigue lives than the Synthes cancellous screws did ( p < 0.001) but shorter fatigue lives than the DePuy-Ace cancellous screws did ( p < 0.0001). Among the cortical screws, the cannulated and solid Synthes screws and the solid Zimmer screws did not differ statistically. The Smith and Nephew Richards cortical screws failed at statistically fewer cycles than the Synthes solid and cannulated cortical screws did ( p < 0.003) but did not statistically differ from the Zimmer screws. The DePuy-Ace titanium alloy cancellous screw had the longest fatigue life of the tested implants by a large margin ( p < 0.0001). The Synthes pure titanium and stainless steel cancellous screws did not significantly differ. CONCLUSIONS: This analysis supports core diameter as the principal factor determining fatigue life as the results paralleled implant geometry. This design modification to improve bending and fatigue strength may come at a price to pullout strength, however, because of a decreased major-to-minor diameter and increased pitch. Cortical screws differed in fatigue performance despite identical dimensions, presumably highlighting the importance of implant processing and machining. Cannulated cortical screws performed well relative to solid screws, thereby supporting their clinical use. Pure titanium and stainless steel cancellous screws performed similarly in fatigue despite differing material properties, presumably because of geometric design differences. This report highlights some of the differences in the in vitro fatigue performance among several commonly used small fragment screws.

Identification of novel polymorphisms in intron 7 of the human p53 gene in acute myeloid leukemia and healthy donors.

Screening for mutations by PCR-SSCP in exons 5 to 9 of the p53 gene in 38 bone marrow or peripheral blood specimens of patients with acute myeloid leukemia (AML) showed abnormal shifts in 9 cases. One reflected a mutation in exon 8, whereas in the other cases there were no exonic mutations identified by sequencing. As PCR primers were chosen annealing in the introns flanking the exon region, following sequencing of the encompassing introns identified 5 base substitutions at various sites in intron 7. Two of them have been described previously [1] and 3 novel polymorphisms could be identified. To determine whether these polymorphisms are linked to the pathogenesis of AML, we screened peripheral blood specimens of 26 healthy controls. We found identical base substitutions in 6 out of 26 controls. Our data suggest that these polymorphisms are not related to the pathogenesis of AML.

Cyclosporin A inhibits cytokine-induced proliferation in B-chronic lymphocytic leukemia.

We investigated the effects of the immunosuppressant cyclosporin A (CsA) on proliferation of neoplastic B-cells from patients with B-chronic lymphocytic leukemia (B-CLL). Cell growth was induced in vitro by tumor necrosis factor alpha (TNF-alpha (8/16), interleukin 2 (IL-2 (9/16) or both (7/16), in 4 cases spontaneous proliferation was observed. We were able to demonstrate that CsA inhibits cytokine-induced proliferation, as measured by [3H]-thymidine incorporation, in all cases responsive to TNF-alpha or IL-2 as well as in spontaneous proliferation. CsA did not increase the fraction of trypan blue positive cells or apoptosis. Growth inhibition by CsA occurred in a dose dependent manner: 100 ng/ml CsA was the optimal concentration which blocked about 90% of cytokine induced or spontaneous proliferation. We could also demonstrate that the effect of CsA was reversible and that no blocking effect was observed when CsA was added later than 48 hours after stimulation. Cell cycle analysis using propidium iodide as a DNA stain demonstrated that CsA prohibited the progression of B-CLL cells from the G1-phase to the S-phase of the cell cycle. However, we were also able to show that TNF-alpha induced proliferation of hairy cell leukemia (HCL) was not affected by CsA. This observation indicates that the inhibitory activity of CsA seems to be restricted to only a few haematological diseases such as B-CLL.