Vibration-induced climbing of drops

We report an experimental study of liquid drops moving against gravity, when placed on a vertically vibrating inclined plate, which is partially wetted by the drop. The frequency of vibrations ranges from 30 to 200 Hz, and, above a threshold in vibration acceleration, drops experience an upward motion. We attribute this surprising motion to the deformations of the drop, as a consequence of an up or down symmetry breaking induced by the presence of the substrate. We relate the direction of motion to contact angle measurements. This phenomenon can be used to move a drop along an arbitrary path in a plane, without special surface treatments or localized forcing.Comment: 4 pages, 7 figure

Characteristic Angles in the Wetting of an Angular Region: Deposit Growth

As was shown in an earlier paper [1], solids dispersed in a drying drop migrate to the (pinned) contact line. This migration is caused by outward flows driven by the loss of the solvent due to evaporation and by geometrical constraint that the drop maintains an equilibrium surface shape with a fixed boundary. Here, in continuation of our earlier paper [2], we theoretically investigate the evaporation rate, the flow field and the rate of growth of the deposit patterns in a drop over an angular sector on a plane substrate. Asymptotic power laws near the vertex (as distance to the vertex goes to zero) are obtained. A hydrodynamic model of fluid flow near the singularity of the vertex is developed and the velocity field is obtained. The rate of the deposit growth near the contact line is found in two time regimes. The deposited mass falls off as a weak power Gamma of distance close to the vertex and as a stronger power Beta of distance further from the vertex. The power Gamma depends only slightly on the opening angle Alpha and stays between roughly -1/3 and 0. The power Beta varies from -1 to 0 as the opening angle increases from 0 to 180 degrees. At a given distance from the vertex, the deposited mass grows faster and faster with time, with the greatest increase in the growth rate occurring at the early stages of the drying process.Comment: v1: 36 pages, 21 figures, LaTeX; submitted to Physical Review E; v2: minor additions to Abstract and Introductio

Oscillatory fracture path in thin elastic sheet

We report a novel mode of oscillatory crack propagation when a cutting tip is driven through a thin brittle polymer film. The phenomenon is so robust that it can easily be reproduced at hand (using CD packaging material for example). Careful experiments show that the amplitude and wavelength of the oscillatory crack path scale lineraly with the width of the cutting tip over a wide range of lenghtscales but are independant of the width of thje sheet and the cutting speed. A simple geometric model is presented, which provides a simple but thorough interpretation of the oscillations.Comment: 6 pages, submitted to Comptes Rendus Academie des Sciences. Movies available at http://www.lmm.jussieu.fr/platefractur

Cracks in rubber under tension exceed the shear wave speed

The shear wave speed is an upper limit for the speed of cracks loaded in tension in linear elastic solids. We have discovered that in a non-linear material, cracks in tension (Mode I) exceed this sound speed, and travel in an intersonic range between shear and longitudinal wave speeds. The experiments are conducted in highly stretched sheets of rubber; intersonic cracks can be produced simply by popping a balloon.Comment: 4 pages, 5 eps figure

A common mechanism for recruiting the Rrm3 and RTEL1 accessory helicases to the eukaryotic replisome

The eukaryotic replisome is assembled around the CMG (CDC45-MCM-GINS) replicative helicase, which encircles the leading-strand DNA template at replication forks. When CMG stalls during DNA replication termination, or at barriers such as DNA-protein crosslinks on the leading strand template, a second helicase is deployed on the lagging strand template to support replisome progression. How these ‘accessory’ helicases are targeted to the replisome to mediate barrier bypass and replication termination remains unknown. Here, by combining AlphaFold structural modelling with experimental validation, we show that the budding yeast Rrm3 accessory helicase contains two Short Linear Interaction Motifs (SLIMs) in its disordered N-terminus, which interact with CMG and the leading-strand DNA polymerase Polε on one side of the replisome. This flexible tether positions Rrm3 adjacent to the lagging strand template on which it translocates, and is critical for replication termination in vitro and Rrm3 function in vivo. The primary accessory helicase in metazoa, RTEL1, is evolutionarily unrelated to Rrm3, but binds to CMG and Polε in an analogous manner, revealing a conserved docking mechanism for accessory helicases in the eukaryotic replisome

CMG helicase disassembly is essential and driven by two pathways in budding yeast

The CMG helicase is the stable core of the eukaryotic replisome and is ubiquitylated and disassembled during DNA replication termination. Fungi and animals use different enzymes to ubiquitylate the Mcm7 subunit of CMG, suggesting that CMG ubiquitylation arose repeatedly during eukaryotic evolution. Until now, it was unclear whether cells also have ubiquitin-independent pathways for helicase disassembly and whether CMG disassembly is essential for cell viability. Using reconstituted assays with budding yeast CMG, we generated the mcm7-10R allele that compromises ubiquitylation by SCFDia2. mcm7-10R delays helicase disassembly in vivo, driving genome instability in the next cell cycle. These data indicate that defective CMG ubiquitylation explains the major phenotypes of cells lacking Dia2. Notably, the viability of mcm7-10R and dia2Δ is dependent upon the related Rrm3 and Pif1 DNA helicases that have orthologues in all eukaryotes. We show that Rrm3 acts during S-phase to disassemble old CMG complexes from the previous cell cycle. These findings indicate that CMG disassembly is essential in yeast cells and suggest that Pif1 family helicases might have mediated CMG disassembly in ancestral eukaryotes

The continuing saga of patents and non-invasive prenatal testing

This is the final version. Available on open access from Wiley via the DOI in this recordObjective: This paper examines the IP landscape for NIPT in three key regions: USA; Europe, with particular focus on the UK, and Australia. Method: We explore the patent law issues against the commercial and healthcare environment in these regions, and consider the implications for development and implementation of NIPT. Results: There are many patents held by many parties internationally, with litigation over these patents ongoing in many countries. Importantly, there are significant international differences in patent law, with patents invalidated in the USA that remain valid in Europe. Despite the many patents and ongoing litigation, there are multiple providers of testing internationally, and patents do not appear to be preventing patient access to testing for those who can pay out of pocket. Conclusion: The patent situation in NIPT remains in a state of flux, with uncertainty about how patent rights will be conferred in different jurisdictions, and how patents might affect clinical access. However, patents are unlikely to result in a monopoly for a single provider, with several providers and testing technologies, including both public and private sector entities, likely to remain engaged in delivery of NIPT. However, the effects on access in public healthcare systems are more complex and need to be monitored.Economic and Social Research Council (ESRC)Australian Research CouncilNational Institute for Health Research (NIHR