Two-Dimensional Finite Element Analysis of Turning Processes

Despite crucial efforts invested into computational methods, explicit dynamics simulation of cutting operations may still be unacceptably expensive. Therefore, in many cases a two-dimensional model is considered. Here an overview of the possibilities of two-dimensional simulations is given. For this, simulation and measurement of a straight turning process on AISI 1045 steel is presented. In the numerical analysis, material behavior and its failure was described by Johnson-Cook law, considering damage evolution. Coupled thermo-mechanical model with mass-scaling and adaptive remeshing was built. The numerically obtained cutting force was compared to the measured data. It was found that the forces obtained with simulation and the measured ones show good agreement. Sensitivity analyses were performed to examine the influence of specific parameters on the reaction force. The effect of these parameters is also shown

Effect of Land Use on the Benthic Diatom Community of the Danube River in the Region of Budapest

(1) Urbanization significantly influences the ecosystems of rivers in various ways, including the so-called loading effect of wastewater production. Benthic diatoms are used in ecological status assessments of waters. Beside species composition, traits can be used as indicators. We aimed to evaluate how the loading of the large city of Budapest manifests in the physico-chemical variables of the River Danube and what species composition and trait response this loading results in for the benthic diatom communities. (2) Weekly samplings were performed at points upstream and downstream of Budapest on both riverbanks. Samples were compared, based on general physical-chemical variables and the concentration of thirty-four elements, as well as species composition and seven traits of species of diatom communities. Ecological status was assessed using the Specific Pollution Sensitivity Index (IPS). (3) Only a few measured environmental variables showed differences between the sampling points, suggesting that the nutrient loading has significantly decreased due to the installation of several efficiently working wastewater treatment plants since the introduction of the European Union Water Framework Directive. In contrast, the species composition and traits of species showed the effect of land use. Benthic diatoms indicate the environmental changes caused by land use in the longer-term, while chemical measurements reflect instantaneous status

Enhancement of chicken primordial germ cell in vitro maintenance using an automated cell image analyser

Primordial germ cells (PGCs) were isolated from blood samples of chicken embryos. We established four PGC lines: two males (FS-ZZ-101, GFP-ZZ-4ZP) and two females (FS-ZW-111, GFP-ZW-5ZP). We could not detect a significant difference in the marker expression profile, but there was a remarkable difference between the proliferation rates of these PGC lines. We monitored the number of PGCs throughout a three-day period using a high-content screening cell imaging and analysing system (HCS). We compared three different initial cell concentrations in the wells: similar to 1000 cells (1x), similar to 4000 (4x) and similar to 8000 (8x). For the GFP-ZW-5ZP, FS-ZZ-101 and FS-ZW-111 PGC lines the lowest doubling time was observed at 4x concentration, while for GFP-ZZ-4ZP we found the lowest doubling time at 1x concentration. At 8x initial concentration, the growth rate was high during the first two days for all cell lines, but this was followed by the appearance of cell aggregates decreasing the cell growth rate. We could conclude that the difference in proliferation rate could mainly be attributed to genotypic variation in the established PGC lines, but external factors such as cell concentration and quality of the culture medium also affect the growth rate of PGCs

Cell Size Decrease and Altered Size Structure of Phytoplankton Constrain Ecosystem Functioning in the Middle Danube River Over Multiple Decades

Reduced body size is among the universal ecological responses to global warming. Our knowledge on how altered body size affects ecosystem functioning in ectothermic aquatic organisms is still limited. We analysed trends in the cell size structure of phytoplankton in the middle Danube River over a 34-year period at multiple levels: (1) average cell size of assemblages (ACS), (2) within the centric diatom community and (3) in the dominant centric diatom taxon: Stephanodiscus. We asked whether global warming and human impacts affected the average cell size of phytoplankton. Also, whether the altered size structure affected how chlorophyll-a, as an ecosystem functioning measure, relates to the ACS of phytoplankton. The cell size of phytoplankton decreased significantly at all organisation levels, and the assemblages became more dispersed in cell size over time. Environmental variables related to global warming and human impacts affected the ACS of phytoplankton significantly. The relationship between chlorophyll-a and the ACS of phytoplankton shifted from negative linear to broad and then narrow hump shape over time. Longer water residence time, warming and decline in nutrients and suspended solids decrease the ACS of phytoplankton in the middle Danube and expectedly in other large rivers. Our results suggest that cell size decrease in phytoplankton, especially of centric diatoms, constrains planktic algal biomass production in large rivers, independently of algal density. Such cell size decrease may also affect higher trophic levels and enhance the more frequent occurrence of “clear-water” plankton in large, human-impacted rivers under global change

Relative spraint density and genetic structure of otter (Lutra lutra) along the Drava River in Hungary

In this study we used genetic based approaches to estimating population size and structure of Eurasian otter along the Drava River in Hungary, and compared these results to traditional survey based methods. The relative spraint density of otter was estimated based on the number of fresh (Df) and total number (Dt) of spraints collected on standard routes over a two-year period. Nine microsatellite loci were screened, generating 17 individual otter genotypes composed of 45 different alleles. The expected heterozygosity ranged from 0.53 to 0.89 and observed heterozygosity from 0.25 to 0.92. The mean density (Dg) estimated over six different sites was 0.17 individuals per km of shoreline. A close correlation was found between the number of genotypes and spraint counts along a standard route (fresh spraints: rP = 0.85, P < 0.01; total spraints rP = 0.76, P <0.05). All genotypes found within the 50 km-long study area were closely related (Dm ranged between 0.08 and 0.21)