ALBERT

Description: Living microorganisms inhabit every environment of the biosphere but only in the last decades their importance governing biochemical cycles in deep sediments has been widely recognized. Most investigations have been accomplished in the marine realm whereas there is a clear paucity of comparable studies in lacustrine sediments. One of the main challenges is to define geomicrobiological proxies that can be used to identify different microbial signals in the sediments. Laguna Potrok Aike, a maar lake located in Southeastern Patagonia, has an annually not stratifying cold water column with temperatures ranging between 4 and 10 °C, and most probably an anoxic water/sediment interface. These unusual features make it a peculiar and interesting site for geomicrobiological studies. Living microbial activity within the sediments was inspected by the first time in a sedimentary core retrieved during an ICDP-sponsored drilling operation. The main goals to study this cold subsaline environment were to characterize the living microbial consortium; to detect early diagenetic signals triggered by active microbes; and to investigate plausible links between climate and microbial populations. Results from a meter long gravity core suggest that microbial activity in lacustrine sediments can be sustained deeper than previously thought due to their adaptation to both changing temperature and oxygen availability. A multi-proxy study of the same core allowed defining past water column conditions and further microbial reworking of the organic fraction within the sediments. Methane content shows a gradual increase with depth as a result of the fermentation of methylated substrates, first methanogenic pathway to take place in the shallow subsurface of freshwater and subsaline environments. Statistical analyses of DGGE microbial diversity profiles indicate four clusters for Bacteria reflecting layered communities linked to the oxidant type whereas three clusters characterize Archaea communities that can be linked to both denitrifiers and methanogens. Independent sedimentary and biological proxies suggest that organic matter production and/or preservation have been lower during the Medieval Climate Anomaly (MCA) coinciding with a low microbial colonization of the sediments. Conversely, a reversed trend with higher organic matter content and substantial microbial activity characterizes the sediments deposited during the Little Ice Age (LIA). Thus, the initial sediments deposited during distinctive time intervals under contrasting environmental conditions have to be taken into account to understand their impact on the development of microbial communities throughout the sediments and their further imprint on early diagenetic signals.

Description: Authigenic minerals can form in the water column and sediments of lakes, either abiotically or mediated by biological activity. Such minerals have been used as paleosalinity and paleoproductivity indicators and reflect trophic state and early diagenetic conditions. They are also considered potential indicators of past and perhaps ongoing microbial activity within sediments. Authigenic concretions, including vivianite, were described in late glacial sediments of Laguna Potrok Aike, a maar lake in southernmost Argentina. Occurrence of iron phosphate implies specific phosphorus sorption behavior and a reducing environment, with methane present. Because organic matter content in these sediments was generally low during glacial times, there must have been alternative sources of phosphorus and biogenic methane. Identifying these sources can help define past trophic state of the lake and diagenetic processes in the sediments. We used scanning electron microscopy, phosphorus speciation in bulk sediment, pore water analyses, in situ ATP measurements, microbial cell counts, and measurements of methane content and its carbon isotope composition (d13C CH4) to identify components of and processes in the sediment. The multiple approaches indicated that volcanic materials in the catchment are important suppliers of iron, sulfur and phosphorus. These elements influence primary productivity and play a role in microbial metabolism during early diagenesis. Authigenic processes led to the formation of pyrite framboids and revealed sulfate reduction. Anaerobic oxidation of methane and shifts in pore water ion concentration indicated microbial influence with depth. This study documents the presence of active microbes within the sediments and their relationship to changing environmental conditions. It also illustrates the substantial role played by microbes in the formation of Laguna Potrok Aike concretions. Thus, authigenic minerals can be used as biosignatures in these late Pleistocene maar sediments.

Description: J. Tuma, O. Lyutakov, I. Huttel, P. Slepicka, and V. Svorcik Thin poly(methylmethacrylate) films doped by or covalently attached to disperse Red 1 acrylate (DR1) were patterned by laser scanning and simultaneous sample movement in confocal microscope. In both cases, periodical structure due to Marangoni effect is created. Modified polymers surfaces were analy ... [J. Appl. Phys. 114, 093104 (2013)] published Fri Sep 6, 2013.

Description: L. Kilanski, K. Szalowski, R. Szymczak, M. Gorska, E. Dynowska et al. We present the studies of electrical transport and magnetic interactions in ZnMnGeAs crystals with low Mn content 0

Description: G. Y. Gao, Z. B. Yang, W. Huang, H. Z. Zeng, Y. Wang et al. Epitaxial Mn-doped BiFeO (MBFO) thin films were grown on GaAs (001) substrate with SrTiO (STO) buffer layer by pulsed laser deposition. X-ray diffraction results demonstrate that the films show pure (00l) orientation, and MBFO (100)//STO(100), whereas STO (100)//GaAs (110). Piezoresponse force micro ... [J. Appl. Phys. 114, 094106 (2013)] published Fri Sep 6, 2013.

Description: Yanan Huang, Bangchuan Zhao, Shuai Lin, Wenhai Song, and Yuping Sun The effects of Ir doping on the low-temperature thermal and electrical transport properties of CaCoIrO (0

Description: P. Orlandi In this paper, it is demonstrated by DNS of turbulent rough channels that a proportionality between u-tilde| (the wall-normal Reynolds stress u-tilde= at the top of the roughness elements) and the roughness function does exist. This observation confirmed by experiments allows the derivation of a sim ... [Phys. Fluids 25, 110813 (2013)] published Fri Sep 6, 2013.

Description: Alessandra Adrover We investigate the effects of secondary (transverse) flows on convection-dominated dispersion of pressure driven, open column laminar flow in a conduit with rectangular cross-section. We show that secondary flows significantly reduce dispersion (enhancing transverse diffusion) in Taylor-Aris regime ... [Phys. Fluids 25, 093601 (2013)] published Fri Sep 6, 2013.

Description: Michael E. Mueller and Heinz Pitsch An integrated kinetics-based Large Eddy Simulation (LES) approach for soot evolution in turbulent reacting flows is applied to the simulation of a Pratt & Whitney aircraft gas turbine combustor, and the results are analyzed to provide insights into the complex interactions of the hydrodynamics, mixi ... [Phys. Fluids 25, 110812 (2013)] published Fri Sep 6, 2013.

Description: D. M. Valiev, V. Bychkov, V. Akkerman, L.-E. Eriksson, and C. K. Law The present paper addresses the phenomenon of spontaneous acceleration of a premixed flame front propagating in micro-channels, with subsequent deflagration-to-detonation transition. It has recently been shown experimentally [M. Wu, M. Burke, S. Son, and R. Yetter, Proc. Combust. Inst. 31, 2429 (200 ... [Phys. Fluids 25, 096101 (2013)] published Fri Sep 6, 2013.