An experimental apparatus for the study of high-temperature degradation and solid-deposit formation of lubricants.

When exposed to high surface temperatures, engine lubricating oils degrade and may form solid deposits, which cause operational issues and increase shutdown time and maintenance costs. Despite its being a common issue in engine operation, the information available on the mechanics of this phenomenon is still lacking, and the experimental data and conditions must be updated to match the improvements in both lubricant stability and engine efficiency. To this end, an experimental apparatus has been developed to study the mechanisms that lead to the degradation and deposit formation of lubricants at high temperatures. The apparatus is designed to operate at pressures up to 69 bar, surface temperatures up to 650 °C, oil bulk temperatures up to 550 °C, and flow rates of <14 mL/min. In this apparatus, the oil is cycled through a heated test section, and deposits accumulate on the heated surface. The time required for deposits to start accumulating under the test conditions is determined based on the recorded temperature traces, and collected oil and deposit samples may be analyzed to determine changes in composition over time due to high-temperature exposure. The removable test section can be modified to accommodate different geometries, surface materials, and flow paths to adapt the instrument to a range of potential research directions. This paper presents the technical details of the new apparatus and the steps taken to characterize the experimental conditions. In addition, sample data are provided to show the unique capabilities of the new instrument, and an Arrhenius plot for Castrol Perfecto X 32 in the surface temperature range of 445-475 °C is presented as a demonstration of its use for quantifying the coking delay time. The new instrument detailed herein is the first such device to demonstrate a reliable, lab-scale technique for studying lube oil coke formation and deposition at temperatures and pressures of interest to power generation gas turbines.

Flow cytometric assay detecting cytotoxicity against human endogenous retrovirus antigens expressed on cultured multiple sclerosis cells.

Damage of target cells by cytotoxicity, either mediated by specific lymphocytes or via antibody-dependent reactions, may play a decisive role in causing the central nervous system (CNS) lesions seen in multiple sclerosis (MS). Relevant epitopes, antibodies towards these epitopes and a reliable assay are all mandatory parts in detection and evaluation of the pertinence of such cytotoxicity reactions. We have adapted a flow cytometry assay detecting CD107a expression on the surface of cytotoxic effector cells to be applicable for analyses of the effect on target cells from MS patients expressing increased amounts of human endogenous retrovirus antigens. MS patients also have increased antibody levels to these antigens. The target cells are spontaneously growing peripheral blood mononuclear cells (PBMCs) of B cell lineage, expressing human endogenous retrovirus HERV epitopes on their surface. Polyclonal antibodies against defined peptides in the Env- and Gag-regions of the HERVs were raised in rabbits and used in antibody-dependent cell-mediated cytotoxicity (ADCC) -assays. Rituximab® (Roche), a chimeric monoclonal antibody against CD20 expressed primarily on B cells, was used as control antibody. Without antibodies this system is suitable for analyses of natural killer cell activity. In optimization of the assay we have used effector lymphocytes from healthy donors. The most effective effector cells are CD56(+) cells. CD8(+) T cells also express CD107a in ADCC. Using the adapted assay, we demonstrate significant ADCC activity to target cells expressing HERV epitopes, and additionally a low level of NK activity.

DNA preparation from cryopreserved bone marrow cell samples.

1. Quickly thaw cryopreserved MNCs (1 ml) in 9 ml PBS supplemented with DNase I immediately before use (final concentration: 0.1 mg/ml). 2. Incubate at 37 degrees C for 10 min. 3. Wash twice in PBS supplemented with 2% human AB serum at 4 degrees C. 4. Incubate with saturating amounts of selected MoAbs for 20 min at 4 degrees C. 5. Wash twice in PBS supplemented with 2% human AB serum at 4 degrees C. 6. Immunomagnetic bead separation of viable cells as described by Lea et al. (1). 7. DNA extraction. 8. Measure quality and yield of DNA by spectrophotometry. In conclusion, the DNA extraction method presented here, based on DNase I pretreatment of the cryopreserved cells followed by an immunological selection for viable cells, provides cell suspensions with close to 100% viability; thus, high-quality DNA can be extracted even from cryopreserved cell samples of low initial viability. Furthermore, using this method DNA analyses can be performed on selected cellular subsets if desired. We thus recommend this method for DNA analyses in hematological research when the only materials available are cryopreserved bone marrow samples of low viability.

Plasma fibronectin in acute myeloid leukaemia.

In 13 patients with acute myeloid leukaemia (AML), plasma fibronectin (P-FN) was measured before, during and after chemotherapy. Pre-treatment concentrations of P-FN were within the reference range and significantly higher than the nadir value (p less than 0.05). A rise in body temperature by more than 1 degree C induced a significant fall in P-FN (p less than 0.05) and transfusion with freshly drawn blood products could prevent this fall. P-FN concentrations were significantly higher in patients obtaining complete haematological remission than in patients in whom remission could not be induced (p less than 0.001). This difference could not be attributed to transfusion or febrile episodes.

Calculation of the individual and population doses on Danish territory resulting from hypothetical core-melt accidents at the Barsebäck reactor.

Individual and population doses on Danish territory are calculated from hypothetical, severe core-melt accidents at the Swedish nuclear plant at Barsebäck. The release fractions for these accidents are taken from WASH-1400. Based on parametric studies, doses are calculated for very unfavourable, but not incredible weather conditions. The probability of such conditions in combination with wind direction towards Danish territory is estimated. Doses to bone marrow, lungs, GI-tract and thyroid are calculated using dose models developed at Risø. These doses are found to be consistent with doses calculated with the models used in WASH-1400.