Dynamic NMR Relaxometry as a Straightforward Measurement of Concentration Variations in Colloidal Gels.

We show that dynamic NMR relaxometry allows one to probe the particle size or the concentration evolution over time in homogeneous colloidal suspensions or the concentration in different regions of heterogeneous suspensions, up to large volume fractions. We first demonstrate that the NMR transverse relaxation time is independent of the gel structure at the particle scale so that it only slightly varies during the gelation of a colloidal suspension. The evolution over time of the NMR transverse relaxation time during gel drying and its analysis with the help of the fast-exchange assumption extended to a partially saturated medium then allowed us to identify three successive regimes: homogeneous shrinkage, desaturation, and molecular film regime.

Inferring phylogenetic networks from multifurcating trees via cherry picking and machine learning.

The Hybridization problem asks to reconcile a set of conflicting phylogenetic trees into a single phylogenetic network with the smallest possible number of reticulation nodes. This problem is computationally hard and previous solutions are limited to small and/or severely restricted data sets, for example, a set of binary trees with the same taxon set or only two non-binary trees with non-equal taxon sets. Building on our previous work on binary trees, we present FHyNCH, the first algorithmic framework to heuristically solve the Hybridization problem for large sets of multifurcating trees whose sets of taxa may differ.

Constructing phylogenetic networks via cherry picking and machine learning.

Background: Combining a set of phylogenetic trees into a single phylogenetic network that explains all of them is a fundamental challenge in evolutionary studies. Existing methods are computationally expensive and can either handle only small numbers of phylogenetic trees or are limited to severely restricted classes of networks.

Results: In this paper, we apply the recently-introduced theoretical framework of cherry picking to design a class of efficient heuristics that are guaranteed to produce a network containing each of the input trees, for practical-size datasets consisting of binary trees.

Slow spreading with a large contact angle on hygroscopic materials.

Water transfer in wood plays a major role during the life time of timber structures but the physics of the various processes involved, such as wetting and imbibition, is not fully understood. Here we show that the angle of contact of a water drop placed in contact with an air dry wood surface is initially larger than 90°, then the drop slowly spreads over the surface, while the apparent (macroscopic) contact angle decreases down to a few tens of degrees. We show that similar results are obtained with a model material, hydrogel, as soon as a perturbation is induced onto the line of contact.