arXiv subjects

Jean-Franccois Berret

Publications and source records attributed to Jean-Franccois Berret.

4 recordsLinked to original sources

arXiv2021

Silicone incorporation into an esterquat based fabric softener in presence of guar polymers

Fabric softeners are widely used to make clothes soft and impart nice smell. Household conditioners are water-based formulations consisting of quaternary ammonium surfactants assembled in vesicles. On the other hand, formulations used for textiles finishing are typically silicone oil emulsions. Here, these technologies are combined in a novel industrial formulation which contains both surfactant vesicles and silicone oil. In particular, we insert an amino-modified silicone oil into a recently developed softener comprising vesicles of an esterquat and guar polymers. Two strategies based on the use of esterquat or guar gum as stabilizers for the silicone incorporation in the fabric softener are proposed. Dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryoTEM), optical and fluorescent microscopy are applied to study the stability and the insertion of the silicone oil into the softener. It is shown that silicone oil is stabilized by the surfactant and the guar gum in nano- or micro-metric droplets. The vesicles structure and properties are not affected by the silicone oil while the formulation stability is preserved. These findings suggest that the proposed route for adding silicone oil into a topical conditioner is a promising route for multipurpose fabric softener development.

cond-mat.soft↗

arXiv2020

Alveolar mimics with periodic strain and its effect on the cell layer formation

We report on the development of a new model of alveolar air-tissue interface on a chip. The model consists of an array of suspended hexagonal monolayers of gelatin nanofibers supported by microframes and a microfluidic device for the patch integration. The suspended monolayers are deformed to a central displacement of 40-80 um at the air-liquid interface by application of air pressure in the range of 200-1000 Pa. With respect to the diameter of the monolayers that is 500 um, this displacement corresponds to a linear strain of 2-10% in agreement with the physiological strain range in the lung alveoli. The culture of A549 cells on the monolayers for an incubation time 1-3 days showed viability in the model. We exerted a periodic strain of 5% at a frequency of 0.2 Hz during 1 hour to the cells. We found that the cells were strongly coupled to the nanofibers, but the strain reduced the coupling and induced remodeling of the actin cytoskeleton, which led to a better tissue formation. Our model can serve as a versatile tool in lung investigations such as in inhalation toxicology and therapy.

cond-mat.soft↗

arXiv2020

Common trends in the epidemic of Covid-19 disease

The discovery of SARS-CoV-2, the responsible virus for the Covid-19 epidemic, has sparked a global health concern with many countries affected. Developing models that can interpret the epidemic and give common trend parameters are useful for prediction purposes by other countries that are at an earlier phase of the epidemic; it is also useful for future planning against viral respiratory diseases. One model is developed to interpret the fast-growth phase of the epidemic and another model for an interpretation of the entire data set. Both models agree reasonably with the data. It is shown by the first model that during the fast phase, the number of new infected cases depends on the total number of cases by a power-law relation with a scaling exponent equal to 0.82. The second model gives a duplication time in the range 1 to 3 days early in the start of the epidemic, and another parameter alpha = 0.1-0.5) that deviates the progress of the epidemic from an exponential growth. Our models may be used for data interpretation and for guiding predictions regarding this disease, e.g. the onset of the maximum in the number of new cases.

q-bio.PE↗

arXiv2017

Compaction and condensation of DNA mediated by the C-terminal domain of Hfq

Hfq is a bacterial protein that is involved in several aspects of nucleic acids metabolism. It has been described as one of the nucleoid associated proteins shaping the bacterial chromosome, although it is better known to influence translation and turnover of cellular RNAs. Here, we explore the role of Escherichia coli Hfq C-terminal domain in the compaction of double stranded DNA. Various experimental methodologies, including fluorescence microscopy imaging of single DNA molecules confined inside nanofluidic channels, atomic force microscopy, isothermal titration microcalorimetry, and electrophoretic mobility assays have been used to follow the assembly of the C-terminal and N-terminal regions of Hfq on DNA. Results highlight the role of Hfq C-terminal arms in DNA binding, change in mechanical properties of the double helix and compaction of DNA into a condensed form. The propensity for bridging and compaction of DNA by the C-terminal domain might be related to aggregation of bound protein and may have implications for protein binding related gene regulation.

physics.bio-ph↗