High-throughput triggered merging of surfactant-stabilized droplet pairs using traveling surface acoustic waves

We present an acoustofluidic device for fluorescently triggered merging of surfactant-stabilized picoliter droplet pairs at high throughput. Droplets that exceed a preset fluorescence threshold level are selectively merged by a traveling surface acoustic wave (T-SAW) pulse. We characterize the operation of our device by analyzing the merging efficiency as a function of acoustic pulse position, duration, and acoustic pressure amplitude. We probe droplet merging at different droplet rates and find that efficient merging occurs above a critical acoustic power level. Our results indicate that the efficiency of acoustically induced merging of surfactant stabilized droplets is correlated with acoustic streaming velocity. Finally, we discuss how both time-averaged and instantaneous acoustic pressure fields can affect the integrity of surfactant layers. Our technique, by allowing the merging of up to 105 droplets per hour, shows great potential for integration into microfluidic systems for high-throughput and high-content screening applications

Demonstrating the Use of Optical Fibres in Biomedical Sensing:A Collaborative Approach for Engagement and Education

This paper demonstrates how research at the intersection of physics, engineering, biology and medicine can be presented in an interactive and educational way to a non-scientific audience. Interdisciplinary research with a focus on prevalent diseases provides a relatable context that can be used to engage with the public. Respiratory diseases are significant contributors to avoidable morbidity and mortality and have a growing social and economic impact. With the aim of improving lung disease understanding, new techniques in fibre-based optical endomicroscopy have been recently developed. Here, we present a novel engagement activity that resembles a bench-to-bedside pathway. The activity comprises an inexpensive educational tool ($70) adapted from a clinical optical endomicroscopy system and tutorials that cover state-of-the-art research. The activity was co-created by high school science teachers and researchers in a collaborative way that can be implemented into any engagement development process

Hi-sAFe: a 3D agroforestry model for integrating dynamic tree–crop interactions

Agroforestry, the intentional integration of trees with crops and/or livestock, can lead to multiple economic and ecological benefits compared to trees and crops/livestock grown separately. Field experimentation has been the primary approach to understanding the tree–crop interactions inherent in agroforestry. However, the number of field experiments has been limited by slow tree maturation and difficulty in obtaining consistent funding. Models have the potential to overcome these hurdles and rapidly advance understanding of agroforestry systems. Hi-sAFe is a mechanistic, biophysical model designed to explore the interactions within agroforestry systems that mix trees with crops. The model couples the pre-existing STICS crop model to a new tree model that includes several plasticity mechanisms responsive to tree–tree and tree–crop competition for light, water, and nitrogen. Monoculture crop and tree systems can also be simulated, enabling calculation of the land equivalent ratio. The model’s 3D and spatially explicit form is key for accurately representing many competition and facilitation processes. Hi-sAFe is a novel tool for exploring agroforestry designs (e.g., tree spacing, crop type, tree row orientation), management strategies (e.g., thinning, branch pruning, root pruning, fertilization, irrigation), and responses to environmental variation (e.g., latitude, climate change, soil depth, soil structure and fertility, fluctuating water table). By improving our understanding of the complex interactions within agroforestry systems, Hi-sAFe can ultimately facilitate adoption of agroforestry as a sustainable land-use practice

Thermal behaviour and performance of two field experimental insulation covers to control sulfide oxidation at Meadowbank mine, Nunavut

Insulation covers are an appealing reclamation approach to control sulfide oxidation in tailings storage facilities located in the Arctic. In this study, the thermal behaviour and effectiveness of insulation covers for the reclamation of the Meadowbank mine’s tailings storage facility were assessed using both laboratory-based tests and field experimental cells. Oxygen consumption tests performed in controlled laboratory conditions indicated that a temperature of 0 °C is adequate to control Meadowbank’s tailings oxidation. Two instrumented experimental covers were constructed with 2 and 4 m of nonreactive waste rocks. Thermal monitoring of the experimental cells was conducted over 4.5 years and demonstrated a thermal regime dominated by heat conduction. The 2 m cover displayed temperatures at the tailings–cover interface greater than 0 °C for 94 to 124 days per year, whereas the tailings under the 4 m cover stayed below 0 °C year-round. Field oxygen consumption tests showed a reduction of 70%–90% in the oxygen uptakes measured for covered tailings compared to uncovered tailings. Calculations of yearly oxygen consumption fluxes showed oxygen fluxes less than 2 mol·m−2·year−1, confirming the effectiveness of the cover configurations to control sulfide oxidation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

La Commission européenne 1973-1986Histoire et mémoires d'une institution

Vingt-deux professeurs ou chercheurs issus de quinze universités ont uni leurs forces pour rédiger cet ouvrage, coordonné par l'université catholique de Louvain, à Louvain-la-Neuve. Ils ont bénéficié d'un accès privilégié aux archives de la Commission et ont pu s'appuyer sur les témoignages de nombreux «anciens» de la Commission, commissaires ou fonctionnaires, qui ont été les acteurs de cette période. Un projet similaire avait déjà mené à la publication d'un ouvrage consacré aux années fondatrices de l'institution entre 1958 et 1972

Surface chemical characterization of different pyrite size fractions for flotation purposes

International audienceA surface chemical approach of different pyrite size fraction is developed in this paper in the prospect of addressing the well-known coarse pyrite flotation challenge for environmental purposes. This work aims at exploring the effect of particle size on pyrite surface chemistry through the study of three pyrite size fractions up to 425 μm. Pyrite surface evolution was investigated through dry crushing, air oxidation and aqueous conditioning using X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared spectroscopy (DRIFT) as complementary surface characterization tools. XPS, which characterized the outmost surface (about 40 Å depth), indicated that pyrite size fraction did not impact its surface chemistry after crushing. However, DRIFT which characterizes the whole oxidation layer, led to the conclusion that ferric sulfate was more abundant in the finer fraction than in the two coarser fractions. Those two surface characterization tools allowed a thorough insight into the three-dimensional oxidation product structures of pyrite from different size fractions. The surface evolution of coarse fractions had the same surface evolution trend when submitted to aging and conditioning processes than the fine pyrite size fraction, studied in previous works, in terms of surface species speciation and their relative proportion. Those results led to a better understanding of particle size impacts on pyrite surface chemistry

Molecular basis of mRNA cap recognition by Influenza B polymerase PB2 subunit

Influenza virus polymerase catalyzes the transcription of viral mRNAs by a process known as “cap-snatching”, where the 5'-cap of cellular pre-mRNA is recognized by the PB2 subunit and cleaved 10-13 nucleotides downstream of the cap by the endonuclease PA subunit. Although this mechanism is common to both influenza A (FluA) and B (FluB) viruses, FluB PB2 recognizes a wider range of cap structures including m7GpppGm-, m7GpppG-, and GpppG-RNA, while FluA PB2 utilizes methylated G-capped RNA specifically. Biophysical studies with isolated PB2 cap-binding domain (PB2cap) confirm that FluB PB2 has expanded mRNA cap recognition capability although the affinities towards m7GTP are significantly reduced when compared to FluA PB2. The X-ray co-structures of the FluB PB2cap with bound cap analogs m7GTP and GTP reveal an inverted GTP binding mode that is distinct from the cognate m7GTP binding mode shared between FluA and FluB PB2. These results delineate the commonalities and differences in the cap-binding site between FluA and FluB PB2 and will aid structure-guided drug design efforts to identify dual inhibitors of both FluA and FluB PB2