MIXS on BepiColombo and its DEPFET based focal plane instrumentation Treis, J.; Andricek, L.; Aschauer, F. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2010, Letnik:
624, Številka:
2
Journal Article
Recenzirano
Focal plane instrumentation based on DEPFET Macropixel devices, being a combination of the Detector–Amplifier structure DEPFET with a silicon drift chamber (SDD), has been proposed for the MIXS ...(Mercury Imaging X-ray Spectrometer) instrument on ESA's Mercury exploration mission BepiColombo. MIXS images X-ray fluorescent radiation from the Mercury surface with a lightweight X-ray mirror system on the focal plane detector to measure the spatially resolved element abundance in Mercury's crust. The sensor needs to have an energy resolution better than 200
eV FWHM at 1
keV and is required to cover an energy range from 0.5 to 10
keV, for a pixel size of
300
×
300
μ
m
2
. Main challenges for the instrument are radiation damage and the difficult thermal environment in the mercury orbit. The production of the first batch of flight devices has been finished at the MPI semiconductor laboratory. Prototype modules have been assembled to verify the electrical properties of the devices; selected results are presented here. The prototype devices, Macropixel prototypes for the SIMBOL-X focal plane, are electrically fully compatible, but have a pixel size of 0.5×0.5
mm
2. Excellent homogeneity and near Fano-limited energy resolution at high readout speeds have been observed on these devices.
In pursuit of superconductivity in p-type silicon (Si), we are using a single atomic layer of aluminum (Al) sandwiched between a Si substrate and a thin Si epi-layer. The delta layer was fabricated ...starting from an ultra high vacuum (UHV) flash anneal of Si(100) surface, followed by physical vapor deposition of Al monolayer. To activate the Al dopants, the sample was then annealed in-situ at 550 °C for 1 min. The Si capping layer was electron-beam evaporated in-situ at room temperature, followed by an ex-situ anneal at 550 °C for 10 min to recrystallize the Si capping layer. Low temperature magnetotransport measurements yield a maximum hole mobility of 20 cm2/V/s at a carrier density 1.39 × 1014 holes/cm2, which corresponds to ≈ (0.93 ± 0.1) holes per dopant atom. No superconductivity was observed in these devices even at T < 300 mK. Atom probe tomography and energy-dispersive X-ray spectroscopy analyses suggest that the Al dopants become distributed over ≈ (17 to 25) nm thickness. Redistribution of Al dopants reduces Al atomic concentration in Si matrix below the critical density to observe superconductivity.
The glycoprotein hormone erythropoietin (EPO) is a key regulator in the production of red blood cells. EPO is produced mainly in the embryonic liver and kidney of adults. Other organs are also known ...to express varying amounts of EPO. In our study, we have analyzed the epigenetic regulation of EPO in human cancer cell lines by DNA methylation assays, chromatin immunoprecipitation, RT-PCR, and promoter analysis under different growth conditions. Moreover, the growth-related effects of ectopic EPO expression were analyzed in a head and neck cancer cell line. We found frequent DNA hypermethylation of the CpG island promoter and enhancer of EPO in different cancer cell lines. Aberrant methylation of EPO promoter was observed in primary lung, head and neck, breast, and liver cancers. Hypermethylation of EPO was associated with a decreased expression of EPO in cancer cells. Treatment of cancer cell lines with 5-aza-2'-deoxycytidine (Aza), an inhibitor of DNA methylation, reactivated EPO expression under hypoxia. In contrast, in the liver cancer cell line HepB3, the EPO promoter was unmethylated, and a high EPO expression was observed independently of Aza treatment. Moreover, in vitro hypermethylation of the EPO promoter and enhancer reduced expression of a reporter gene under normoxia and hypoxia. Induction of EPO under hypoxia was accompanied by increased histone H3 acetylation and reduced histone H3 lysine 9 trimethylation. In a head and neck cancer cell line, which exhibited low EPO levels, ectopic expression of EPO significantly enhanced proliferation under normoxia and hypoxia. In summary, we show that hypermethylation of regulatory sequences of EPO is frequently observed in tumors and that this aberrant methylation induces epigenetic silencing of EPO in cancer cells.
Chronic cardiac rejection is represented by cardiac allograft vasculopathy (CAV) and cardiac interstitial fibrosis (CIF) known to cause severe complications. These processes are accompanied by ...remarkable changes in the cardiac extra cellular matrix (cECM). The aim of our study was to analyse the cECM remodelling in chronic rejection and to elucidate a potential role of ED-A domain containing fibronectin (ED-A⁺ Fn), alpha smooth muscle actin (ASMA) and B domain containing tenascin-C (B⁺ Tn-C). A model of chronic rejection after heterotopic rat heart transplantation was used. Allografts, recipient and control hearts were subjected to histological assessment of rejection grade, to real-time PCR based analysis of 84 genes of ECM and adhesion molecules and to immunofluorescence labelling procedures, including ED-A⁺ Fn, ASMA and B⁺ Tn-C antibodies. Histological analysis revealed different grades of chronic rejection. By gene expression analysis, a relevant up-regulation of the majority of ECM genes in association with chronic rejection could be shown. For 8 genes, there was a relevant up-regulation in allografts as well as in the corresponding recipient hearts. Association of ASMA positive cells with the grade of chronic rejection could be proven. In CAV and also in CIF there were extensive co-depositions of ED-A⁺ Fn, ASMA and B⁺ Tn-C. In conclusion, chronic cardiac allograft rejection is associated with a cECM remodelling. ASMA protein deposition in CAV, and CIF is a valuable marker to detect chronic rejection. Interactions of VSMCs and Fibro-/Myofibroblasts with ED-A⁺ Fn and B⁺ Tn-C might functionally contribute to the development of chronic cardiac rejection.
The e+e- linear collider physics program sets highly demanding requirements on the accurate determination of charged particle trajectories close to the interaction point.
Background and Objective
Nutrition and body weight are modifying factors for periodontitis. The purpose of this study was to quantify two molecules (ghrelin and chemerin), released in association ...with food intake and obesity, in periodontally healthy and diseased individuals with respect to different body mass categories.
Material and Methods
The two main groups (patients with chronic periodontitis and periodontally healthy/gingivitis volunteers) were subdivided into groups of subjects with normal weight body mass index (BMI) <25 and groups of overweight/obese subjects (BMI ≥25). Subgingival bacteria were analysed and the levels of acylated and total ghrelin, chemerin and interleukin‐1β (IL‐1β) were assessed in saliva, gingival crevicular fluid and serum.
Results
The amount of Treponema denticola present subgingivally was significantly higher in the groups of patients with chronic periodontitis as well as in periodontally healthy/gingivitis individuals with BMI ≥25 than in periodontally healthy/gingivitis individuals with BMI <25. The amount of total ghrelin in gingival crevicular fluid differed significantly between the groups, with the lowest levels found in the group of patients with chronic periodontitis and BMI ≥25. The levels of chemerin in gingival crevicular fluid were significantly higher in each chronic periodontitis group than in periodontally healthy/gingivitis individuals with BMI <25. However, the level of IL‐1β in the gingival crevicular fluid was most differentiating between the groups, with the highest levels found in the group of patients with chronic periodontitis and BMI <25 and the lowest levels in periodontally healthy/gingivitis individuals with BMI <25. No significant differences between any groups were seen for chemerin or for acylated ghrelin in the stimulated whole saliva, or for acylated and total ghrelin in peripheral blood serum. The BMI correlated with the serum level of chemerin.
Conclusion
Low ghrelin and high chemerin levels in the gingival crevicular fluid might be linked to periodontal disease and overweight/obesity. However, unlike IL‐1β, the levels of chemerin and ghrelin in gingival crevicular fluid are not reliable indicators of periodontal destruction.
Dolomite precipitation models and kinetics are debated and complicated due to the complex and temporally fluctuating fluid chemistry and different diagenetic environments. Using well-established ...isotope systems ( delta super(18)O, delta super(13)C, super(87)Sr/ super(86)Sr), fluid inclusions and elemental data, as well as a detailed sedimentological and petrographic data set, we established the precipitation environment and subsequent diagenetic pathways of a series of Proterozoic to Pleistocene syn-depositional marine evaporative (sabkha) dolomites, syn-depositional non-marine evaporative (lacustrine and palustrine) dolomites, altered marine ("mixing zone") dolomites and late diagenetic hydrothermal dolomites. These data form the prerequisite for a systematic investigation of dolomite magnesium isotope ratios ( delta super(26)Mg sub(dol)). Dolomite delta super(26)Mg ratios documented here range, from -2.49ppt to -0.45ppt ( delta super(26)Mg sub(mean) = -1.75 plus or minus 1.08ppt, n = 42). The isotopically most depleted end member is represented by earliest diagenetic marine evaporative sabkha dolomites (-2.11 plus or minus 0.54ppt 2 sigma , n = 14). In comparing ancient compositions to modern ones, some of the variation is probably due to alteration. Altered marine (-1.41 plus or minus 0.64ppt 2 sigma , n = 4), and earliest diagenetic lacustrine and palustrine dolomites (-1.25 plus or minus 0.86ppt 2 sigma , n = 14) are less negative than sabkha dolomites but not distinct in composition. Various hydrothermal dolomites are characterized by a comparatively wide range of delta super(26)Mg ratios, with values of -1.44 plus or minus 1.33ppt (2 sigma , n = 10). By using fluid inclusion data and clumped isotope thermometry ( Delta sub(47)) to represent temperature of precipitation for hydrothermal dolomites, there is no correlation between fluid temperature ( similar to 100 to 180 degree C) and dolomite Mg isotope signature (R super(2) = 0.14); nor is there a correlation between delta super(26)Mg sub(dol) and delta super(18)O sub(dol). Magnesium-isotope values of different dolomite types are affected by a complex array of different Mg sources and sinks, dissolution/precipitation and non-equilibrium fractionation processes and overprinted during diagenetic resetting. Further progress on the use of delta super(26)Mg sub(dol) as a proxy will require new theoretical and experimental data for Delta super(26)Mg sub(fluid-dol) that includes dehydration effects of the free Mg aquo ion versus fluid temperature. In ancient diagenetic systems, complex variables must be considered. These include fluid chemistry and physical properties, Mg sources and sinks, temporal changes during precipitation and post-precipitation processes including open and closed system geochemical exchange with ambient fluids. All of these factors complicate the application of delta super(26)Mg sub(dol) as proxy for their depositional or diagenetic environments. Nevertheless, the data shown here also indicate that delta super(26)Mg sub(dol) can in principle be interpreted within a detailed framework of understanding.
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