Genome-wide data from medieval German Jews show that the Ashkenazi founder event pre-dated the 14th century

We report genome-wide data for 33 Ashkenazi Jews (AJ), dated to the 14th century, following a salvageexcavation at the medieval Jewish cemetery of Erfurt, Germany. The Erfurt individuals are geneticallysimilar to modern AJ and have substantial Southern European ancestry, but they show more variabilityin Eastern European-related ancestry than modern AJ. A third of the Erfurt individuals carried the samenearly-AJ-specific mitochondrial haplogroup and eight carried pathogenic variants known to affect AJtoday. These observations, together with high levels of runs of homozygosity, suggest that the Erfurtcommunity had already experienced the major reduction in size that affected modern AJ. However, theErfurt bottleneck was more severe, implying substructure in medieval AJ. Together, our results suggestthat the AJ founder event and the acquisition of the main sources of ancestry pre-dated the 14th centuryand highlight late medieval genetic heterogeneity no longer present in modern AJ

Experimental and Computational Analysis of Fluid Interfaces Influenced by Soluble Surfactant

The present contribution is the result of a collaboration between the Max Planck Institute of Colloids and Interfaces and the Technical University of Darmstadt (MMA group). The main objective is to give a quantitative description of fluid interfaces influenced by surfactants, comparing experimental and computational results. Surfactants are amphiphilic molecules subject to ad- and desorption processes at fluid interfaces. In fact, they accumulate at the interface, modifying the respective interfacial properties. Since these interfaces are moving, continuously deforming and expanding, the local time-dependent interfacial coverage is the most relevant quantity. The description of such processes poses severe challenges both to the experimental and to the simulation sides. Two prototypical problems are considered for comparison between experiments and simulations: the formation of droplets under the influence of surfactants and rising bubbles in aqueous solutions contaminated by surfactants. Direct Numerical Simulations (DNS) provide valuable insights into local quantities such as local surfactant distribution and surface tension, but at high computational costs and restricted to short time frames. On the other hand, experiments can give global quantities necessary for the validation of the numerical procedures and can afford longer time frames. The two methodologies thus yield complementary results which help to understand such complex interfacial phenomena

On the interaction of softwood hemicellulose with cellulose surfaces in relation to molecular structure and physicochemical properties of hemicellulose

The substantial part of the water-soluble hemicellulose fraction, obtained when processing cellulose to produce paper and other products, has so far been discarded. The aim of this work is to reveal the interfacial properties of softwood hemicellulose (galactoglucomannan, GGM) in relation to their molecular and solution structure. In this study the sugar composition of GGM was characterised by chemical analysis as well as 1D and 2D NMR spectroscopy. Previously it has been demonstrated that hemicellulose has high affinity towards cellulose and has the ability to alter the properties of cellulose based products. This study is focused on the interactions between hemicellulose and the cellulose surface. Therefore, adsorption to hydrophobized silica and cellulose surfaces of two softwood hemicellulose samples and structurally similar seed hemicelluloses (galactomannans, GMs) was studied with ellipsometry, QCM-D and neutron reflectometry. Aqueous solutions of all samples were characterized with light scattering to determine how the degree of side-group substitution and molecular weight affect the conformation and aggregation of these polymers in the bulk. In addition, hemicellulose samples were studied with SAXS to investigate backbone flexibility. Light scattering results indicated that GM polymers form globular particles while GGMs were found to form rod-like aggregates in the solution. The polysaccharides exhibit higher adsorption to cellulose than on hydrophobic surfaces. A clear correlation between the increase in molecular weight of polysaccharides and increasing adsorbed amount on cellulose was observed, while the adsorbed amount on the hydrophobic surface was fairly independent of the molecular weight. The obtained layer thickness was compared with bulk scattering data and the results indicated flat conformation of the polysaccharides on the surface