Climato-stratigraphic subdivision of the Pleistocene in Schleswig-Holstein, Germany and adjoining areas

In Schleswig-Holstein detailed petrographical and palynological studies were undertaken with samples from exposures and core drillings examined over the last four decades. Analyses of the gravel fraction and ‘indicator rocks’ of glacial deposits were used for stratigraphical interpretations and correlation. Glaciofluvial sediments were dated by TL and OSL. Combined with the stratigraphical information from organic deposits, a new climato-stratigraphic table of the Pleistocene for Schleswig-Holstein with a revised subdivision of the Middle and Late Pleistocene could be established. The pollen sequence of the oldest Pleistocene warm phase (Warmhörn-Thermomer) is published for the first time. The complete Early Pleistocene and lower Middle Pleistocene stratigraphical sequence is documented at Lieth and at Gorleben (Lower Saxony) in two continuous successions of organic beds developed during warm phases alternating with cold phase deposits. The uppermost part of the Lieth succession and the lowermost part of Gorleben overlap. The combined succession provides a unique reference for correlations through Europe. No more than three cold stages involving glaciation are demonstrated to exist currently in Schleswig-Holstein, the Elsterian and the Saalian in the upper Middle Pleistocene, and the Weichselian in the Late Pleistocene. A possible pre-Elsterian glaciation is discussed. The Holsteinian is correlated with MIS 9e. The Saalian includes a lower part with non-glacial cold phases and warm phases, the ‘Wacken-Warmzeit’ (=Dömnitz) and the ‘Leck-Warmzeit’ correlated with MIS 7e and MIS 7c respectively, and a glacial upper part. During the Weichselian probably two phases of glaciation existed, the first in the early Middle Weichselian (‘Ellund-Phase’; late MIS 4 or/and the early MIS 3), the second in the Upper Weichselian (MIS 2). The Weichselian glaciation of Schleswig-Holstein ends around 15 ka BP when huge stagnant and dead ice masses of the Young Baltic glacier advance (‘Mecklenburg-Phase’) melted.researc

Improved detection of long-range residual dipolar couplings in weakly aligned samples by Lee-Goldburg decoupling of homonuclear dipolar truncation

Homonuclear 1H residual dipolar couplings (RDCs) truncate the evolution of transverse 1H magnetization of weakly aligned molecules in high-resolution NMR experiments. This leads to losses in sensitivity or resolution in experiments that require extended 1H evolution times. Lee-Goldburg decoupling schemes have been shown to remove the effects of homonuclear dipolar couplings, while preserving chemical shift evolution in a number of solid-state NMR applications. Here, it is shown that the Lee-Goldburg sequence can be effectively incorporated into INEPT- or HMQC-type transfer schemes in liquid state weak alignment experiments in order to increase the efficiency of the magnetization transfer. The method is applied to the sensitive detection of 1HN-13C long-range RDCs in a three-dimensional HCN experiment. As compared to a conventional HCN experiment, an average sensitivity increase by a factor of 2.4 is obtained for a sample of weakly aligned protein G. This makes it possible to detect 170 long-range 1HN-13C RDCs for distances up to 4.9

Schwermineralanalyse von Geschiebemergeln, ein Hilfsmittel für die Moränenstratigraphie? Diskussion anhand von Zählungen aus Schleswig-Holstein

Aus der Literatur entnommene Schwermineralanalysen von Geschiebemergeln werden mit einigen neuen Analysen zusammen ausgewertet. Von den elsterzeitlichen bis zu den weichselzeitlichen Geschiebemergeln gibt es in den Schwermineralassoziationen zwar deutliche Verschiebungen, jedoch zeigen die Auswertediagramme breite, sich meist stark überlappende Streufelder. Eine eindeutige Unterscheidung der Geschiebemergel aus aufeinanderfolgenden Vereisungen ist nicht möglich. Die Schwermineralassoziation kennzeichnet — wie auch andere petrographische Parameter — eine bestimmte Grundmoränenfazies. Sie kann sich in gleich alten Moränen regional ändern, aber auch in verschieden alten Moränen in ähnlicher Zusammensetzung auftreten.researc

Die Schwermineral-Verteilung im Quartärprofil der Forschungsbohrung Tüschenbek (Schleswig-Holstein)

Sandige Proben aus den in der Forschungsbohrung Tüschenbek (Schleswig-Holstein) angetroffenen quartären Serien zeigen altersbedingte Unterschiede im Schwermineral-Gehalt: Von der Elsterzeitlichen zu jüngeren Serien nimmt der Gehalt an opaken und stabilen Mineralen ebenso wie der von Epidot ab, der von Hornblende dagegen zu. Eine Aufarbeitung von Tertiär-Sedimenten hat offenbar bei den Weichselzeitlichen Proben dazu geführt, dass der Gehalt an stabilen Mineralen etwas erhöht ist.researc

Biophysical and structural investigation of bacterially expressed and engineered CCR5, a G protein-coupled receptor

The chemokine receptor CCR5 belongs to the class of G protein-coupled receptors. Besides its role in leukocyte trafficking, it is also the major HIV-1 coreceptor and hence a target for HIV-1 entry inhibitors. Here, we report Escherichia coli expression and a broad range of biophysical studies on E. coli-produced CCR5. After systematic screening and optimization, we obtained 10mg of purified, detergent-solubilized, folded CCR5 from 1L culture in a triply isotope-labeled (2H/15N/13C) minimal medium. Thus the material is suitable for NMR spectroscopic studies. The expected α-helical secondary structure content is confirmed by circular dichroism spectroscopy. The solubilized CCR5 is monodisperse and homogeneous as judged by transmission electron microscopy. Interactions of CCR5 with its ligands, RANTES and MIP-1β were assessed by surface plasmon resonance yielding KD values in the nanomolar range. Using size exclusion chromatography, stable monomeric CCR5 could be isolated. We show that cysteine residues affect both the yield and oligomer distribution of CCR5. HSQC spectra suggest that the transmembrane domains of CCR5 are in equilibrium between several conformations. In addition we present a model of CCR5 based on the crystal structure of CXCR4 as a starting point for protein engineerin

Proton irradiation of gold targets for 197(m)Hg production

Introduction Irradiation of gold with protons provides access to no-carrier-added 197mHg and 197Hg. Interests in these radionuclides were awakened by the unique chemical and physical properties of mercury and its compounds combined with convenient nuclear properties like suitable half life (197mHg: T1/2 = 23.8 h, 197Hg: T1/2 = 64.14 h), low energy gamma radiations for imaging, Auger – and conversion electrons for therapy. The high thermal conductivity of gold enables high current irradiations and the monoisotopic natural abundance of 197Au supersedes expensive enrichment of the target material. The 197Au(p,n)197(m)Hg reaction was applied until now only for beam monitoring1, stacked foil meas-urements2 or very small scale tracer production. Material and Methods The irradiations were performed at a Cyclone 18/9 (IBA, Louvain la Neuve, Belgium). Its beam-line was sealed with a 1.0 mm vacuum foil (high purity aluminum, 99.999 %) from Goodfellow (Huntingdon, England). High purity gold disks (23 mm diameter, 2 mm thickness, 99.999% pure, 1 ppm Cu) as target material were purchased from ESPI (Ashland, USA). Gold foils as alternative gold targets (12.5×12.5 mm, 0.25 mm thickness, 99.99+ %, 1 ppm Cu) between an aluminum disk (22 mm diameter, 1 mm thickness, 99.0 %, hard) and an aluminum lid (23 mm diameter, 99.0 %, hard) were purchased from Goodfellow (Huntingdon, England). Hydrochloric acid (30%) and nitric acid (65%) were purchased from Roth (Karlsruhe, Germany) in Rotipuran® Ultra quality. Deionized water with > 18 MΩcm resistivity was prepared by a Milli-Q® system (Millipore, Molsheim, France). For separation of target material and side products a liquid-liquid extraction method (Gold was extracted with methyl isobutyl ketone (MIBK) from 2 M HCl target solution) and an ion exchange method (cation exchange resin (Dowex50W-x8, 100–200 mesh, H+ form) were applied. Results and Conclusion No-carrier-added 197(m)Hg was produced from gold via the 197Au(p,n)197(m)Hg reaction at proton energies of 10 MeV in sufficient quantity and quality for imaging studies. Two different methods were studied for the separation of Hg radionuclides generated from Au targets. The results demonstrate the possibility to produce 197(m)Hg from gold at low proton energies. Combined with the presented radiochemical separation methods, the 197Au(p,n) reaction could be the basis for repeatable production of 197(m)Hg for imaging and therapy research on sufficient activity level

Experimental Study of Condensation of Water on Polydimethylsiloxane-Coated Copper Surfaces

Modification of surfaces to enable dropwise condensation is a promising approach for achieving high condensation rates. In this work, we present an experimental study on condensation of water on copper surfaces coated with an ultrathin, 5 nm - 10 nm thick polydimethylsiloxane (PDMS) layer. This hydrophobic coating possesses a very low thermal resistance, which in combination with copper substrate enables achieving high condensation rates in heat transfer applications. The PDMS-coated copper substrates have been fabricated with a newly developed method, which involves turning, sanding, polishing, oxidation, and polymer coating steps. The measured static contact angle was 110{\deg}, and a the contact angle hysteresis was 2{\deg}. The achieved very low hysteresis is advantageous for promoting dropwise condensation. The surface showed no ageing effects during 100 repetitions of advancing and receding contact angle (ARCA) measurements. Condensation heat transfer on uncoated and PDMS-coated copper surfaces surfaces has been studied experimentally in a saturated water vapor atmosphere at 60{\deg}C. An enhancement factor for heat flux and heat transfer coefficient of up to 1.6 was found on PDMS-coated copper surfaces compared to uncoated surfaces, which decreased to 1.1 on second and third day of condensation operation. Images of the condensation surface were recorded while conducting condensation experiments and post processed to evaluate drop departure diameter and frequency of drop sweeping events. It has been shown that the behavior of the heat transfer coefficient correlates with the frequency of the sweeping events

Mode competition in broad-ridge-waveguide lasers

The lateral brightness achievable with high-power GaAs-based laser diodes having long and broad waveguides is commonly regarded to be limited by the onset of higher-order lateral modes. For the study of the lateral-mode competition two complementary simulation tools are applied, representing different classes of approximations. The first tool bases on a completely incoherent superposition of mode intensities and disregards longitudinal effects like spatial hole burning, whereas the second tool relies on a simplified carrier transport and current flow. Both tools yield agreeing power-current characteristics that fit the data measured for 5 to 23 µm wide ridges. Also, a similarly good qualitative conformance of the near and far fields is found. However, the threshold of individual modes, the partition of power between them at a given current, and details of the near and far fields show differences. These differences are the consequence of a high sensitivity of the mode competition to details of the models and of the device structure. Nevertheless, it can be concluded concordantly that the brightness rises with increasing ridge width irrespective of the onset of more and more lateral modes. The lateral brightness 2W · mm¯¹ 1mrad¯¹ at 10MW · cm¯²2 power density on the front facet of the investigated laser with widest ridge (23 µm) is comparable with best values known from much wider broad-area lasers. In addition, we show that one of the simulation tools is able to predict beam steering and coherent beam

Mode competition in broad-ridge-waveguide lasers

The lateral brightness achievable with high-power GaAs-based laser diodes having long and broad waveguides is commonly regarded to be limited by the onset of higher-order lateral modes. For the study of the lateral-mode competition two complementary simulation tools are applied, representing different classes of approximations. The first tool bases on a completely incoherent superposition of mode intensities and disregards longitudinal effects like spatial hole burning, whereas the second tool relies on a simplified carrier transport and current flow. Both tools yield agreeing power-current characteristics that fit the data measured for 5 to 23 µm wide ridges. Also, a similarly good qualitative conformance of the near and far fields is found. However, the threshold of individual modes, the partition of power between them at a given current, and details of the near and far fields show differences. These differences are the consequence of a high sensitivity of the mode competition to details of the models and of the device structure. Nevertheless, it can be concluded concordantly that the brightness rises with increasing ridge width irrespective of the onset of more and more lateral modes. The lateral brightness 2W · mm¯¹ 1mrad¯¹ at 10MW · cm¯²2 power density on the front facet of the investigated laser with widest ridge (23 µm) is comparable with best values known from much wider broad-area lasers. In addition, we show that one of the simulation tools is able to predict beam steering and coherent bea