Micromechanics of root development in soil.

Our understanding of how roots develop in soil may be at the eve of significant transformations. The formidable expansion of imaging technologies enables live observations of the rhizosphere micro-pore architecture at unprecedented resolution. Granular matter physics provides ways to understand the microscopic fluctuations of forces in soils, and the increasing knowledge of plant mechanobiology may shed new lights on how roots perceive soil heterogeneity. This opinion paper exposes how recent scientific achievements may contribute to refresh our views on root growth in heterogeneous environments.

Solvothermal synthesis of superhydrophobic hollow carbon nanoparticles from a fluorinated alcohol.

A new and simple method of synthesizing fluorinated carbon at the gram scale is presented by reacting a fluorinated alcohol with sodium at elevated temperatures in a sealed Teflon reactor. The resulting carbon nanoparticles are around 100 nm in diameter, and display a hollow shell morphology, with a significant amount of fluorine doped into the carbon. The nanoparticles disperse easily in ethanol, and are thermally stable up to 400 °C and 450 °C under air and nitrogen, respectively. The nanoparticle dispersion was printed onto various substrates (paper, cloth, silicon), inducing superhydrophobicity.

Collision-induced dissociation studies of poly(vinylidene) fluoride telomers in an electrospray-ion trap mass spectrometer.

Although fluorinated polymers are widely used in different applications, they are rarely investigated by "soft ionization" techniques such as matrix-assisted laser desorption/ionization and electrospray ionization (ESI). We report here, the desorption and fragmentation of poly(vinylidene) fluoride (PVDF) telomers in an ion trap mass spectrometer coupled to an ESI source. Protonated and lithiated telomers under collision-induced dissociation resonant excitation show mainly HF losses. Fragmentation of protonated telomers can be rationalized by a double proton-transfer mechanism and that of lithiated and anionic telomers by an ion-dipole mechanism. Both mechanisms predict the formation of a stable aromatic or a linear conjugated species, respectively. For lithiated telomers, we could determine the degree of polymerization (n) from the product ion abundance in MS2 experiments. The nature of the end group plays a substantial role in orienting the fragmentation of the PVDF ions. It is interesting to note that, in MS2 experiments, Li+ and F- act as catalysts in the fragmentation of PVDF telomers. Fragmentation of the PVDF telomer backbone was not observed under any experimental conditions.

Synthesis and preliminary assessments of ethyl-terminated perfluoroalkyl nonionic surfactants derived from tris(hydroxymethyl)acrylamidomethane.

We describe the synthesis and preliminary physicochemical and biological assessments of a new class of nonionic hybrid hydrofluoro amphiphiles derived from tris(hydroxymethyl)aminomethane (THAM). The synthesis of the hydrophobic tail of these amphiphiles is based on the preparation of an asymmetrical hydrofluorocarbon derivative containing an ethyl segment, a fluorocarbon core, and an ethyl thiol moiety. This molecule led to either THAM galactosylated monoadducts or telomers. These amphiphiles exhibit neither detergency toward cell membranes nor membrane protein denaturation.