Environmental and Genetic Determinants of Bacterial Microbiota and Parasites Associated with Cottus Across Natural Hybrid Zones

Natural hybrid zones often emerge at habitat clines where distinct populations meet, mate and hybridize. The possible factors that govern the dynamics of a hybrid zone are insufficiently explored. For example symbiotic bacteria and also parasites can induce selection pressure by influencing the host’s immune system, nutrition, development and behavior. These interactions are in turn influenced by environmental factors making it difficult to disentangle all involved components. Here, we use a secondary contact zone where two populations of European freshwater sculpins (pisces), Cottus rhenanus and invasive Cottus, hybridize at a habitat ecotone. This system enables to study the association of symbiotic microbiota, habitat and host genotype to infer whether host-bacterial interaction may act as evolutionary force. The goal was to determine whether skin bacterial communities of hybrid and parental sculpins differ which would then suggest a significant role for microbiota in influencing the sculpins’ distribution. Further teleost fish, Barbatula barbatula and Phoxinus phoxinus, both inhabiting either habitat of the contact zone, served as control for environmental variation. The bacterial community structure of the fish was examined by applying high-throughput sequencing of the 16S rDNA gene from fin clips. The host genetic makeup was inferred based on nuclear SNP markers that permit to classify all fish into parental forms and recent hybrids. By means of additional laboratory experiments we examined the host genetic influence on bacterial communities under controlled environments. Phylogenetic and statistical analyses revealed major differences in bacterial diversity and abundance in distinct host habitats. However, we also identified minor host-specific variation being independent from the environmental variation. These results indicate that bacterial communities in our system are shaped by both, host genetic and environmental factors, and can at least not solely act as selective force against migrants in a Cottus spp. hybrid zone

Synthesis of bulk amorphous and nano-crystalline materials by spray forming

Bulk amorphous and nanocrystalline metallic materials have been observed to possess excellent mechanical and physical properties. The conventional process routes to synthesize such materials are restricted by their ability to achieve rapid solidification which limits the dimensions of the materials produced. In the last ten years, spray forming has been used to avoid these limitations by using its layer by layer deposition of undercooled droplets. The available literature indicates that the opportunities provided by this process can be utilized to produce bulk materials in a single step. In the present paper, an attempt has been made to review the developments in the area of spray forming of amorphous and/or nanocrystalline materials. The effect of process parameters, droplet size distribution in the spray, the thermal conditions of droplets prior to deposition and the deposition surface conditions have been discussed in detail. It has been demonstrate that the layer by layer deposition of undercooled droplets of glass forming alloys on a relatively cold deposition surface is the suitable condition to achieve amorphization/nanocrystallization. A critical analysis of the process parameters and the results has been made based on the composition, glass forming ability and possible mechanisms of microstructural evolution

Synthesis of zeolite-P from coal fly ash derivative and its utilisation in mine-water remediation

Solid residues resulting from the active treatment of acid mine drainage with coal fly ash were successfully converted to zeolite-P under mild hydrothermal treatment conditions. Scanning electron microscopy showed that the zeolite-P product was highly crystalline. The product had a high cation exchange capacity (178.7 meq / 100 g) and surface area (69.1 m2/g) and has potential application in waste-water treatment. A mineralogical analysis of the final product identified zeolite-P, as well as mullite and quartz phases, which indicated incomplete dissolution of the fly ash feedstock during the ageing step. Further optimisation of the synthesis conditions would be required to attain complete utilisation of the feedstock. The zeolite-P was tested for decontamination potential of circumneutral mine water. High removal efficiency was observed in the first treatment, but varied for different contaminants. The synthesised zeolite-P exhibited a high efficiency for the removal of heavy metal cations, such as aluminium, iron, manganese, zinc, copper and nickel, from contaminated mine water, even with repeated use. For potassium, calcium, strontium and barium, the removal was only efficient in the first treatment and decreased rapidly with subsequent treatments, indicating preferential adsorption of the other metals. A continuous release of sodium was observed during decontamination experiments, which decreased with subsequent treatments, confirming that sodium was the main exchangeable charge-balancing cation present in the zeolite-P product

Neuroanatomical and Neuropsychological Markers of Amnestic MCI: A Three-Year Longitudinal Study in Individuals Unaware of Cognitive Decline

Structural brain changes underlying mild cognitive impairment (MCI) have been well-researched, but most previous studies required subjective cognitive complaints (SCC) as a diagnostic criterion, diagnosed MCI based on a single screening test or lacked analyses in relation to neuropsychological impairment. This longitudinal voxel-based morphometry study aimed to overcome these limitations: The relationship between regional gray matter (GM) atrophy and behavioral performance was investigated over the course of 3 years in individuals unaware of cognitive decline, identified as amnestic MCI based on an extensive neuropsychological test battery. Region of interest analyses revealed GM atrophy in the left amygdala, hippocampus, and parahippocampus in MCI individuals compared to normally aging participants, which was specifically related to verbal memory impairment and evident already at the first measurement point. These findings demonstrate that GM atrophy is detectable in individuals with amnestic MCI despite unawareness of beginning cognitive decline. Thus, individuals with GM atrophy in regions associated with verbal memory impairment do not necessarily need to experience SCC before meeting neuropsychological criteria for MCI. These results have important implications for future research and diagnostic procedures of MCI

Laser powder bed fusion of Cu-Ti-Zr-Ni bulk metallic glasses in the Vit101 alloy system

Laser powder bed fusion (PBF-LB/M) of bulk metallic glasses (BMGs) has experienced growing scientific and industrial interest in the last years, with a special focus on application relevant systems based on zirconium. The high cooling rates and the layer-wise build-up process allow overcoming size and geometry limitations typical for conventional casting routes. Yet, the novel production approach requires different alloy characteristics than casting processes. The present work reports for the first time on the PBF-LB/M-processing of three CuTi-based bulk metallic glass formers in the Vit101 system, allowing to exceed the mechanical performance of most additively formed Zr-based BMGs. Furthermore, the influence of alloy properties like thermal stability and toughness on the PBF-LB/M applicability are systematically studied. Thermal stability plays a minor role to produce amorphous specimen, while notch toughness is found to be a more crucial aspect to achieve parts with low defect density and resulting high mechanical performance. The results suggest fundamentally different alloy development strategies adapted to the needs of the PBF-LB/M-process, leaving classical casting-based optimization of glass forming ability behind and evolving towards a rather toughness-oriented optimization

Analytical Modeling of Cooling Rates in PBF-LB/M of Bulk Metallic Glasses

Additive manufacturing through laser powder bed fusion (PBF-LB/M) inheres great potential for the processing of bulk metallic glasses (BMGs). The size-independent high cooling rates during the process benefit the fabrication of large and elaborate amorphous components. Albeit, partial crystallization poses a challenge in additively manufactured BMGs, potentially limiting the resulting mechanical properties. In this matter, the complex thermal history during processing often states a remaining uncertainty. Besides in situ measurements and numerical estimations, analytical models can be used to achieve a deeper understanding of the transient temperature evolution. In this work, an iterative solution to the analytical Rosenthal equation is developed and applied to ZrCuAlNb- and CuTiZrNi-BMGs to predict melt pool dimensions and cooling rates during PBF-LB/M. Therefore, temperature-dependent thermal properties are determined via laser flash measurements. The effective absorptivity of the two materials is measured, and single-line experiments were performed as a validation for the approach.Mechanical Engineerin