Multi-method study of the Middle Pleistocene loess–palaeosol sequence of Köndringen, SW Germany

Loess–palaeosol sequences (LPSs) remain poorly investigated in the southern part of the Upper Rhine Graben but represent an important element to understand the environmental context controlling sediment dynamics in the area. A multi-method approach applied to the LPS at Köndringen reveals that its formation occurred during several glacial–interglacial cycles. Field observations, as well as colour, grain size, magnetic susceptibility, organic carbon, and carbonate content measured in three profiles at 5 cm resolution, provide detailed stratigraphical information. Only minor parts of the LPS are made up of loess sediment, whereas the major parts are polygenetic palaeosols and pedosediments of varying development that are partly intersected, testifying to a complex local geomorphic evolution. The geochronological framework is based on 10 cm resolution infrared-stimulated luminescence (IRSL) screening combined with 18 multi-elevated-temperature post-IR IRSL ages. The luminescence ages indicate that two polygenetic, truncated Luvisols formed during marine isotope stages (MISs) 9(–7?) and MIS 5e, whereas unaltered loess units correspond to the last glacial (MISs 5d–2) and MIS 8. The channel-like structure containing the two truncated Luvisols cuts into &gt; 2 m thick pedosediments apparently deposited during MIS 12. At the bottom of the LPS, a horizon with massive carbonate concretions (loess dolls) occurs, which may correspond to at least one older interglacial.</p

Supramolecular nesting of cyclic polymers

Advances in template-directed synthesis make it possible to create artificial molecules with protein-like dimensions, directly from simple components. These synthetic macromolecules have a proclivity for self-organization that is reminiscent of biopolymers. Here, we report the synthesis of monodisperse cyclic porphyrin polymers, with diameters of up to 21 nm (750 C–C bonds). The ratio of the intrinsic viscosities for cyclic and linear topologies is 0.72, indicating that these polymers behave as almost ideal flexible chains in solution. When deposited on ​gold surfaces, the cyclic polymers display a new mode of two-dimensional supramolecular organization, combining encapsulation and nesting; one nanoring adopts a near-circular conformation, thus allowing a second nanoring to be captured within its perimeter, in a tightly folded conformation. Scanning tunnelling microscopy reveals that nesting occurs in combination with stacking when nanorings are deposited under vacuum, whereas when they are deposited directly from solution under ambient conditions there is stacking or nesting, but not a combination of both

Evidence confirms an anthropic origin of Amazonian Dark Earths

Archaeology of the America

Plasma enhanced atomic layer deposited MoOx emitters for silicon heterojunction solar cells

A method for the deposition of molybdenum oxide MoOx with high growth rates at temperatures below 200 C based on plasma enhanced atomic layer deposition is presented. The stoichiometry of the overstoichiometric MoOx films can be adjusted by the plasma parameters. First results of these layers acting as hole selective contacts in silicon heterojunction solar cells are presented and discusse

Integrated low-temperature process for the fabrication of amorphous Si nanoparticles embedded in Al2O3 for non-volatile memory application (Phys. Status Solidi A 9∕2016)

Among electronic devices, flash memory is one of the most aggressively scaled technologies, already approaching minimum limits of miniaturization. The nano-floating-gate memory (NFGM), which is based on semiconductor or metal nanoparticles embedded in a dielectric matrix, is regarded as one promising route for future nonvolatile memory applications. In their article on pp. 2446–2451, Ilse et al. present a new fabrication process for multilayers of silicon nanoparticles (Si–NPs) embedded in amorphous Al2O3, combining a nonthermal low-pressure inductively coupled plasma process (LPICP) for Si–NPs and thermalatomic layer deposition (ALD) of Al2O3. This low-temperature process provides some advantages compared to common fabrication techniques of Si–NPs in Al2O3, which mostly include annealing steps with temperatures up to 1150 °C to enable Si–NP formation. At temperatures above 800 °C, the number of the typical fixed oxide charges in amorphous Al2O3 vanishes due to crystallization processes. The influence of the fixed oxide charges in Al2O3 on the programming process and retention is investigated and discussed as possibility to enhance long-term storage of information

Influence of black silicon surfaces on the performance of back-contacted back silicon heterojunction solar cells

The influence of different black silicon (b-Si) front side textures prepared by inductively coupled reactive ion etching (ICP-RIE) on the performance of back-contacted back silicon heterojunction (BCB-SHJ) solar cells is investigated in detail regarding their optical performance, black silicon surface passivation and internal quantum efficiency. Under optimized conditions the effective minority carrier lifetime measured on black silicon surfaces passivated with Al2O3 can be higher than lifetimes measured for the SiO2/SiNx passivation stack used in the reference cells with standard KOH textures. However, to outperform the electrical current of silicon back-contact cells, the black silicon back-contact cell process needs to be optimized with aspect to chemical and thermal stability of the used dielectric layer combination on the cell

Reevaluation of Late Pleistocene loess profiles at Remizovka (Kazakhstan) indicates the significance of topography in evaluating terrestrial paleoclimate records

We report on a loess-paleosol sequence (LPS) near Remizovka, located in the northern Tian Shan piedmont of southeastern Kazakhstan. This site represents a key record for Late Pleistocene climatic fluctuations at the intersection of major northern hemisphere climate subsystems. This paper develops a synthesized dataset of previous conflicting studies at Remizovka by characterizing their (paleo)topographic context, which had remained previously overlooked. Digital elevation models, satellite images, and archival photography characterize recent topographic developments. Two well-developed pedocomplexes, which we investigate in detail and date by luminescence mark the paleotopography during Marine Oxygen Isotope Stage (MIS) 5. Peak dust accumulation rates here occurred during the middle MIS 5 and MIS 4/early MIS 3. These are partially comparable with records from neighboring regions, but not in phase with global ice volume records. This discrepancy may be related to a distinct regional environmental response to larger-scale climatic drivers and local topographic influences on dust deposition patterns. Our findings confirm the potential of the LPS Remizovka to provide high-resolution paleoclimate data for the Late Pleistocene. The three-dimensional stratigraphic reconstruction reinforces the caution required to correctly interpret loess formation processes prior to their interpretation as paleoclimate archives, and provides guidelines for a more suitable approach

Properties of black silicon obtained at room-temperature by different plasma modes

Black silicon plasma technology begins to be integrated into the process flow of silicon solar cells. However, most of the current technology is used at cryogenic or very low substrate temperatures. Here, the authors investigate the temperature-dependent properties of black silicon prepared by two different plasma etching techniques for black silicon, a pure capacitively coupled process (CCP), and an inductively and capacitively coupled process (ICP+CCP). It turns out that the ICP+CCP process at room-temperature yields black silicon samples with 93% absorption and minority carrier lifetime above 1 ms. The authors show that these optoelectronic properties are comparable to samples obtained at low temperatures