ALBERT

Description: Abstract Models to explain alluvial system development in rift settings commonly depict fans that are sourced directly from catchments formed in newly uplifted footwalls, which leads to the development of steep‐sided talus‐cone fans in the actively subsiding basin depocentre. The impact of basin evolution on antecedent drainage networks orientated close to perpendicular to a rift axis, and flowing over the developing hangingwall dipslope, remains relatively poorly understood. The aim of this study is to better understand the responses to rift margin uplift and subsequent intrabasinal fault development in determining sedimentation patterns in alluvial deposits of a major antecedent drainage system. Field‐acquired data from a coarse‐grained alluvial syn‐rift succession in the western Gulf of Corinth, Greece (sedimentological logging and mapping) has allowed analysis of the spatial distribution of facies associations, stratigraphic architectural elements and patterns of palaeoflow. During the earliest rifting phase, newly uplifted footwalls redirected a previously established fluvial system with predominantly southward drainage. Footwall uplift on the southern basin margin at an initially relatively slow rate led to the development of an overfilled basin, within which an alluvial fan prograded to the southwest, south, and southeast over a hangingwall dipslope. Deposition of the alluvial system sourced from the north coincided with the establishment of small‐scale alluvial fans sourced from the newly uplifted footwall in the south. Deposits of non‐cohesive debris flows close to the proposed hangingwall fan apex pass gradationally downstream into predominantly bedload conglomerate deposits indicative of sedimentation via hyperconcentrated flows laden with sand‐ and silt‐grade sediment. Subsequent normal faulting in the hangingwall resulted in the establishment of further barriers to stream drainage, blocking flow routes to the south. This culminated in the termination of sediment supply to the basin depocentre from the north, and the onset of underfilled basin conditions as signified by an associated lacustrine transgression. The evolution of the fluvial system described in this study records transitions between three possible end‐member types of interaction between active rifting and antecedent drainage systems: (i) erosion through an uplifted footwall, (ii) drainage diversion away from an uplifted footwall, (iii) deposition over the hangingwall dip‐slope. The orientation of antecedent drainage pathways at a high angle to the trend of a developing rift axis, replete with intrabasinal faulting, exerts a primary control on the timing and location of development of overfilled and underfilled basin states in evolving depocentres. This article is protected by copyright. All rights reserved.

Description: Abstract The most important issue in the processing of nanoscale metal powders is whether the metal nanopowder can be fully consolidated into ultra‐fine‐ or nano‐grained powder metallurgy parts by pressureless sintering. This paper focuses on the sintering behavior of bimodal iron (Fe) nanopowder agglomerates by considering their microstructure and densification kinetics. During the sintering, bimodal Fe nanopowder compacts underwent discontinuous shrinkage behavior until they neared full density. Three contributions to the sintering mechanisms, asymmetric sintering, densification enhancement, and grain growth inhibition, are presented in relation to the effect of bimodal nanopowder structure. Smaller nanoparticles in the bimodal nanopowders, which are predominantly present at the boundaries and interstitial spaces of larger nanoparticles, are responsible for the three mechanisms stated above. This result is strongly supported by the apparent activation energy values ranging from 48.2 to 90.6 kJ/mol, which correspond to the energy for grain‐boundary diffusion in Fe. The experimental results of this study show that bimodal nanopowder agglomerates can be used to produce full density nano‐grained powder metallurgical parts by pressureless sintering.

Description: Abstract Quantification of allogenic controls in rift basin‐fills requires analysis of multiple depositional systems because of marked along‐strike changes in depositional architecture. Here, we compare two coeval Early‐Middle Pleistocene syn‐rift fan deltas that sit 6 km apart in the hangingwall of the Pirgaki‐Mamoussia Fault, along the southern margin of the Gulf of Corinth, Greece. The Selinous fan delta is located near the fault tip, and the Kerinitis fan delta towards the fault centre, but Selinous and Kerinitis have comparable overall aggradational stacking patterns. Selinous comprises fifteen cyclic stratal units (~25 m thick), whereas at Kerinitis eleven (~60 m thick) are present. Eight facies associations are identified. Fluvial and shallow water, conglomeratic facies dominate the major stratal units in the topset region, with shelfal fine‐grained facies constituting ~2 m thick intervals between major topsets units, and thick conglomeratic foresets building down‐dip. It is possible to quantify delta build times (Selinous: 615 kyrs; Kerinitis: 〉450 kyrs), and average subsidence and equivalent sedimentation rates (Selinous: 0.65 m/kyrs; Kerinitis: 〉1.77 m/kyrs). The presence of sequence boundaries at Selinous, but their absence at Kerinitis, enables sensitivity analysis of the most uncertain variables using a numerical model, ‘Syn‐Strat’, supported by an independent unit thickness extrapolation method. Our study has three broad outcomes: 1) the first estimate of lake level change amplitude in Lake Corinth for the Early‐Middle Pleistocene (10‐15 m), which can aid regional palaeoclimate studies and inform broader climate‐system models; 2) demonstration of two complementary methods to quantify faulting and base level signals in the stratigraphic record – forward modelling with Syn‐Strat and a unit thickness extrapolation ‐ which can be applied to other rift basin‐fills; and 3) a quantitative approach to the analysis of stacking patterns and key surfaces that could be applied to stratigraphic pinch‐out assessment and cross‐hole correlations in reservoir analysis. This article is protected by copyright. All rights reserved.

Description: Abstract Since global reanalysis datasets first appeared in the 1990s, they have become an essential tool to understand the climate of the past. The wind power industry extensively uses those products for wind resource assessment, while several climate services for energy rely on them as well. Nowadays various datasets coexist, which complicates the selection of the most suitable source for each purpose. In an effort to identify the products that better represent the wind speed features at turbine hub heights, five state‐of‐the‐art global reanalyses have been analyzed: ERA5, ERA‐Interim, the Japanese 55‐year Reanalysis (JRA55), the Modern Era Retrospective Analysis for Research and Applications‐2 (MERRA2) and the NCEP/NCAR Reanalysis 1 (R1). A multi‐reanalysis ensemble approach is used to explore the main differences amongst these datasets in terms of surface wind characteristics. Then, the quality of the surface and near surface winds is evaluated with a set of 77 instrumented tall towers. Results reveal that important discrepancies exist in terms of boreal winter seasonal means, interannual variability (IAV) and decadal linear trends. The differences in the computation of these parameters, which are mainly concentrated inland, reach up to the order of magnitude of the parameters themselves. The comparison with in‐situ observations shows that the ERA5 surface winds offer the best agreement, correlating and reproducing the observed variability better than a multi‐reanalysis mean in 35.1% of the tall tower sites at a daily time scale. However, none of the reanalyses stands out from the others when comparing seasonal mean winds. Regarding the IAV, near surface100 m winds from ERA5 offer the closest values to the observed IAV. This article is protected by copyright. All rights reserved.

Description: Abnormal gametogenesis and embryonic development may lead to poor health status of the offspring. The operations involved in the assisted reproductive technologies (ARTs) occur during the key stage of gametogenesis and early embryonic development. To assess the potential risk of abnormal lipid metabolism in the liver of adult ARTs offspring, two ARTs mice models derived from preimplantation genetic diagnosis (PGD group) and in vitro cultured embryos without biopsy (IVEM group) were constructed. And control mice were from in vivo naturally conceived (Normal group). The results showed that ARTs offspring had increased body weight and body fat content comparing to normal group. An increasing volume and amount of lipid droplets as well as lipid droplet fusion were found in the hepatocytes of ARTs mice, and a significantly increased liver TG content was also shown in the ARTs mice, which due to the increased TG synthesis and decreased TG transport in the liver. All the results indicated that the manipulations involved in ARTs might play an important role in the lipid accumulation of adult offspring. By analyzing the DNA methylation profiles of 7.5dpc embryos, we proposed that methylation deregulation of the genes related to liver development in ARTs embryos might contribute to the abnormal phenotype in the offspring. The study demonstrated that ARTs procedures have adverse effect on liver development which resulted in abnormal lipid metabolism and induced the potential high risk of fatty liver in adulthood. This article is protected by copyright. All rights reserved

Description: [1]  The gradient in the partial pressure of carbon dioxide (pCO 2 ) across the air-sea boundary layer is the main driving force for the air-sea CO 2 flux. Global data-bases for surface seawater pCO 2 are actually based on pCO 2 measurements from several meters below the sea surface, assuming a homogeneous distribution between the diffusive boundary layer and the upper top meters of the ocean. Compiling vertical profiles of pCO 2 , Temperature and dissolved oxygen in the upper 5-8 meters of the ocean from different biogeographical areas, we detected a mean difference between the boundary layer and 5 m pCO 2 of 13 ± 1 µatm. Temperature gradients accounted for only 11 % of this pCO 2 gradient in the top meters of the ocean, thus, pointing to a heterogeneous biological activity underneath the air-sea boundary layer as the main factor controlling the top meters pCO 2 variability. Observations of pCO 2 just beneath the air-sea boundary layer should be further investigated in order to estimate possible biases in calculating global air-sea CO 2 fluxes.

Description: We investigated the intrinsic (i.e., metabolic character of autotrophs) and extrinsic (i.e., nutrients and light availability) controls on the variation in autotrophic nitrogen (N) cycling in stream ecosystems based on 15 N isotopic incorporation into five autotrophic components (biofilm, filamentous algae, bryophytes, and submerged and emergent macrophytes) differing in structural complexity and metabolic character. Autotrophs from a stream site with depleted 15 N signatures and relatively low concentrations of dissolved inorganic N (DIN) were translocated to three reaches downstream of the same stream with higher 15 N–DIN signatures and DIN concentrations and different light availability. After the translocation, autotrophs showed an asymptotical increase in their 15 N signatures, achieving isotopic equilibrium with the stream water, from which we calculated N uptake and turnover rates for each autotrophic compartment at the three reaches. Uptake rates were highest when both DIN and light availability were also highest. Differences in DIN uptake rates were greater across reaches than among autotrophs, suggesting that autotrophic DIN uptake at both organism and community level is principally controlled by extrinsic factors (e.g., DIN concentration and light incidence). In contrast, variation in N turnover rates was larger among the different autotrophs than among the study reaches, suggesting a stronger control by intrinsic rather than extrinsic factors.