Real time fluorescence detection of exoribonucleases

International audienc

Critical effect of pore characteristics on capillary infiltration in mesoporous films

International audiencea Capillary phenomena governing the mass-transport (capillary filling, condensation/evaporation) has been experimentally investigated in around 20 different silica thin films exhibiting various porosities with pores dimension ranging from 2 to 200 nm. Films have been prepared by sol–gel chemistry combined with soft-templating approaches and controlled dip coating process. Environmental ellipsometric porosimetry combined with electronic microscopy were used to assess the porosity characteristics. Investigation of lateral capillary filling was performed by following the natural infiltration of water and ionic liquids at the edge of a sessile drop in open air or underneath a PDMS cover. The Washburn model was applied to the displacement of the liquid front within the films to deduce the kinetic constants. The role of the different capillary phenomena were discussed with respect to the porosity characteristics (porosity vol%, pore dimensions and constrictions). We show that correlation between capillary filling rate and pore dimensions is not straightforward. Generally, with a minimum of constrictions, faster filling is observed for larger pores. In the case of mesopores (<50 nm in diameter), the presence of bottle necks considerably slows down the infiltration rate. At such a small dimension, evaporation/capillary condensation dynamics, taking place at the meniscus inside the porosity, has to be considered to explain the transport mode. This fundamental study is of interest for applications involving liquids at the interface of mesoporous networks such as nanofluidics, purification, separation, water harvesting or heat transfer

Modification of poly(styrene) thin films and enhancement of cryogenic plasma etching resistance by ruthenium tetroxide vapor staining

International audienc

High aspect ratio etched sub-micron structures in silicon obtained by cryogenic plasma deep-etching through perforated polymer thin films

Cryogenic plasma deep-etching for silicon sub-micron structures was studied with the use of modified poly(styrene) (PS) perforated masks obtained from laterally phase separated PS and poly (lactic acid) PLA blend thin films. PS mask was stained by heavy metal (ruthenium) or transferred to an intermediate hard mask (silicon oxide). For the stained mask, optimization of standard STiGer cryogenic plasma etching process led to etched Si cavities with minimal defects at rate of 0.8 μm/min but within a limited depth (~1.4 μm). For intermediate hard mask, optimized STiGer etching process was used in order to improve the reproducibility and to obtain the deeply etched features up to 10 μm depth with minimal defects. A higher etch rate of around 1.2 μm/min was achieved. Keywords: Polymer mask, STiGer process, Cryogenic etching, Sub-micron hole etchin

Critical effect of pore characteristics on capillary infiltration in mesoporous films

International audienc

Cellular circadian period length inversely correlates with HbA_1c levels in individuals with type 2 diabetes.

The circadian system plays an essential role in regulating the timing of human metabolism. Indeed, circadian misalignment is strongly associated with high rates of metabolic disorders. The properties of the circadian oscillator can be measured in cells cultured in vitro and these cellular rhythms are highly informative of the physiological circadian rhythm in vivo. We aimed to discover whether molecular properties of the circadian oscillator are altered as a result of type 2 diabetes. We assessed molecular clock properties in dermal fibroblasts established from skin biopsies taken from nine obese and eight non-obese individuals with type 2 diabetes and 11 non-diabetic control individuals. Following in vitro synchronisation, primary fibroblast cultures were subjected to continuous assessment of circadian bioluminescence profiles based on lentiviral luciferase reporters. We observed a significant inverse correlation (ρ = -0.592; p &lt; 0.05) between HbA &lt;sub&gt;1c&lt;/sub&gt; values and circadian period length within cells from the type 2 diabetes group. RNA sequencing analysis conducted on samples from this group revealed that ICAM1, encoding the endothelial adhesion protein, was differentially expressed in fibroblasts from individuals with poorly controlled vs well-controlled type 2 diabetes and its levels correlated with cellular period length. Consistent with this circadian link, the ICAM1 gene also displayed rhythmic binding of the circadian locomotor output cycles kaput (CLOCK) protein that correlated with gene expression. We provide for the first time a potential molecular link between glycaemic control in individuals with type 2 diabetes and circadian clock machinery. This paves the way for further mechanistic understanding of circadian oscillator changes upon type 2 diabetes development in humans. RNA sequencing data and clinical phenotypic data have been deposited at the European Genome-phenome Archive (EGA), which is hosted by the European Bioinformatics Institute (EBI) and the Centre for Genomic Regulation (CRG), ega-box-1210, under accession no. EGAS00001003622

Circadian hepatocyte clocks keep synchrony in the absence of a master pacemaker in the suprachiasmatic nucleus or other extrahepatic clocks.

It has been assumed that the suprachiasmatic nucleus (SCN) synchronizes peripheral circadian oscillators. However, this has never been convincingly shown, since biochemical time series experiments are not feasible in behaviorally arrhythmic animals. By using long-term bioluminescence recording in freely moving mice, we show that the SCN is indeed required for maintaining synchrony between organs. Surprisingly, however, circadian oscillations persist in the livers of mice devoid of an SCN or oscillators in cells other than hepatocytes. Hence, similar to SCN neurons, hepatocytes can maintain phase coherence in the absence of Zeitgeber signals produced by other organs or environmental cycles