Christopher Hermann: Mittelalterliche Architektur im Preußenland. Untersuchungen zur Frage der Kunstlandschaft und -geographie, Petersberg 2007

Rezensiert von Dirk Schumann

Magnetofossil Spike During the Paleocene-Eocene Thermal Maximum: Ferromagnetic Resonance, Rock Magnetic, and Electron Microscopy Evidence from Ancora, New Jersey, USA

Previous workers identified a magnetically anomalous clay layer deposited on the northern United States Atlantic Coastal Plain during the Paleocene-Eocene Thermal Maximum (PETM). The finding inspired the highly controversial hypothesis that a cometary impact triggered the PETM. Here we present ferromagnetic resonance (FMR), isothermal and anhysteretic remanent magnetization, first order reversal curve, and transmission electron microscopy analyses of late Paleocene and early Eocene sediments in drillcore from Ancora, New Jersey. A novel paleogeographic analysis applying a recent paleomagnetic pole from the Faeroe Islands indicates that New Jersey during the initial Eocene had a ~6-9 degrees lower paleolatitude (~27.3 degrees for Ancora) and a more zonal shoreline trace than in conventional reconstructions. Our investigations of the PETM clay from Ancora reveal abundant magnetite nanoparticles bearing signature traits of crystals produced by magnetotactic bacteria. This result, the first identification of ancient biogenic magnetite using FMR, argues that the anomalous magnetic properties of the PETM sediments are not produced by an impact. They instead reflect environmental changes along the eastern margin of North America during the PETM that led to enhanced production and/or preservation of magnetofossils

The extensive hydrocarbon-mediated fixation of hydrothermal gold in the Witwatersrand Basin, South Africa

Abstract There is a close spatial relation between high-grade gold mineralization in the Witwatersrand basin and carbonaceous nodules, veins and seams. Hydrocarbons thus may well have been essential in ore genesis. We have sampled four major gold-, uranium- and hydrocarbon-bearing ore horizons, namely the Carbon Leader, Vaal, B and Black reefs, to determine the role of hydrocarbons in the accumulation and hydrothermal fixation of gold. Our multipronged approach included high-resolution scanning and transmission electron microscopy (SEM, TEM), nanotomography with video clips, and geochemical modeling. Post-depositional hydrothermal activity at the peak of regional metamorphism produced an assemblage of quartz, phyllosilicates, brannerite, crandallite, florencite, monazite and gold in all four reefs. The gold, hydrocarbons and associated mineral assemblages are closely related on the micro to nano scale. Gold deposition occurred in interstices, as fracture fillings in detrital minerals, and on the surface of migrated solid hydrocarbon residues. The spherical to elliptical inclusions in the gold consist of an outer pyrobitumen phase and a central void space, partially associated with nanometric gold, uraninite, coffinite and silica. The hydrocarbon-bearing inclusion likely formed by the entrapment of a fossil liquid oil precursor during gold precipitation. The oil was subsequently thermally altered and converted into the final pyrobitumen and gaseous residues. Geochemical calculations to simulate the interaction of an invading hot hydrothermal fluid with the hydrocarbons in the reefs reveal that a very small amount of hydrocarbons will drastically decrease the aqueous solubility of gold and hence cause its instant precipitation. We extend our genetic model for the epigenetic formation of gold in the Witwatersrand. Regional metamorphism promoted the extensive and likely basin-wide circulation of hydrothermal fluids; these were capable of mobilizing substantial amounts of gold. The liquid, gaseous and solid hydrocarbons in the reefs acted as efficient chemical traps for the concentration of gold. Being strong chemical reductants, they caused the rapid precipitation and accumulation of gold on the surface of the fossil oil droplets and already solidified hydrocarbons. The release of the gases from accessible hydrocarbons into the sediments away from their source buffered the redox state of the hydrothermal solutions even at a considerable distance from the pyrobitumen seams and veins, likely resulting in the deposition of gold in the absence of visible hydrocarbons. Although our findings do not explain the ultimate origin and exceptional endowment of gold in the Witwatersrand, we do provide intriguing evidence for the large-scale hydrothermal mobilization, accumulation and fixation of gold mediated by hydrocarbons during post-depositional metamorphism

A microsensor array for biochemical sensing

A microsensor array to measure chemical properties of biological liquids is presented. A hybrid integration technique is used to mount four sensor chips on a micro flow channel: a pressure, temperature, pH, combined pO2 and pCO2 sensor chip. This results in a microsensor array which is developed to meet the technical requirements for space applications. The integration method allows to integrate other types of sensor chips. This multi-purpose and multi-user approach makes the microsensor array suitable for various biochemical applications

Dresdner Schulen: Teil 1

Die Ausstellung des Amtes für Kultur und Denkmalschutz ist eine Arbeit ehrenamtlicher Denkmalpflegerinnen und Denkmalpfleger. Sie trugen in enger Zusammenarbeit mit Schülern und Lehrern der dargestellten Schulen, Geschichtsinitiativen und Ortschronisten einen Hauptteil des bisher überwiegend unveröffentlichten Materials zusammen. Redaktionsschluss: Oktober 201

Dresdner Schulen: Teil 2

Am vorliegenden zweiten Teil der Ausstellung des Amtes für Kultur und Denkmalschutz beteiligten sich in besonderem Maß aktive und ehemalige Schüler und Lehrer der beschriebenen Schulen. Bisher unveröffentlichte Dokumente und Fotos aus privaten Sammlungen und den Schularchiven geben Einblicke in die Höhen und Tiefen der Schulgeschichten. An allen drei vorgestellten Schulstandorten fanden in jüngster Zeit umfassende Sanierungsarbeiten statt. Ein besonderer Dank gebührt deshalb auch den am Bau Beteiligten, die uns bei der Erarbeitung der Ausstellung unterstützten. Redaktionsschluss: Januar 201

Genetic variation of TLR4 influences immunoendocrine stress response: an observational study in cardiac surgical patients

Introduction: Systemic inflammation (e.g. following surgery) involves Toll-like receptor (TLR) signaling and leads to an endocrine stress response. This study aims to investigate a possible influence of TLR2 and TLR4 single nucleotide polymorphisms (SNPs) on perioperative adrenocorticotropic hormone (ACTH) and cortisol regulation in serum of cardiac surgical patients. To investigate the link to systemic inflammation in this context, we additionally measured 10 different cytokines in the serum. Methods: 338 patients admitted for elective cardiac surgery were included in this prospective observational clinical cohort study. Genomic DNA of patients was screened for TLR2 and TLR4 SNPs. Serum concentrations of ACTH, cortisol, interferon (IFN)-, interleukin (IL)-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)- and granulocyte macro-phage-colony stimulating factor (GM-CSF) were determined before surgery, immediately post surgery and on the first postoperative day. Results: 13 patients were identified as TLR2 SNP carrier, 51 as TLR4 SNP carrier and 274 pa-tients as non-carrier. Basal levels of ACTH, cortisol and cytokines did not differ between groups. In all three groups a significant, transient perioperative rise of cortisol could be ob-served. However, only in the non-carrier group this was accompanied by a significant ACTH rise, TLR4 SNP carriers had significant lower ACTH levels compared to non-carriers ((mean[95% confidence intervals]) non-carriers: 201.9[187.7 to 216.1]pg/ml; TLR4 SNP car-riers: 149.9[118.4 to 181.5]pg/ml; TLR2 SNP carriers: 176.4[110.5 to 242.3]pg/ml). Compared to non-carriers, TLR4 SNP carriers showed significant lower serum IL-8, IL-10 and GM-CSF peaks ((mean[95% confidence intervals]): IL-8: non-carriers: 42.6[36.7 to 48.5]pg/ml, TLR4 SNP carriers: 23.7[10.7 to 36.8]pg/ml; IL-10: non-carriers: 83.8[70.3 to 97.4]pg/ml, TLR4 SNP carriers: 54.2[24.1 to 84.2]pg/ml; GM-CSF: non-carriers: 33.0[27.8 to 38.3]pg/ml, TLR4 SNP carriers: 20.2[8.6 to 31.8]pg/ml). No significant changes over time or between the groups were found for the other cytokines. Conclusions: Regulation of the immunoendocrine stress response during systemic inflamma-tion is influenced by the presence of a TLR4 SNP. Cardiac surgical patients carrying this ge-notype showed decreased serum concentrations of ACTH, IL-8, IL-10 and GM-CSF. This finding might have impact on interpreting previous and designing future trials on diagnosing and modulating immunoendocrine dysregulation (e.g. adrenal insufficiency) during systemic inflammation and sepsis