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A survey was conducted to produce reliable epidemiological data concerning the role played by alcohol and drugs in fatal road accidents in France. The aims are to describe the conduct of the survey, evaluate the overall quality of the findings, and analyze the substances consumed by the involved drivers. A comparison between drivers involved under the influence of alcohol only, cannabis only, or both substances is emphasized.By a June 1999 law, all drivers in France involved in an immediate fatality accident between October 2001 and 2003 had to undergo a urine test and, if that was not possible or the test proved positive, had a blood sample taken in order to test for drugs (cannabis, cocaine, heroin, amphetamines). The results were combined with the usual procedures of the police force, which include the results of tests for illegal alcohol levels. A unique and reliable set of accident data on the role of drugs was thus compiled for epidemiological purposes: 10,000 accident reports involving over 17,000 drivers were analyzed. The responsibility level of each driver involved in an accident was determined. Results were generated for a representative sample of about 11,000 drivers.Alcohol levels above the legal limit (0.5 g/L of blood) were found in 21% of all drivers involved in accidents (killed, injured, or unharmed). Cannabis headed the list of illicit drugs detected, with a prevalence of 6.8% (THCor = 1 ng/mL); it was present in the under-35s and especially the under-25s. About 40% of drivers under the influence of cannabis also had an illegal alcohol level. The other drugs, whether alone or in association with cannabis, are relatively rare. Accident characteristics of drivers detected positive for cannabis only are markedly different from drivers under the influence of alcohol. The overrepresentation of drivers responsible, from 1.7 over the whole population, rises to 2.3 for cannabis alone (THCor = 1 ng/mL), to 9.4 for alcohol alone (or =0.5 mg/L), and to 14.1 for the alcohol-cannabis combination.The high incidence (26%) of alcohol or drugs among the population of drivers involved in fatal accidents highlights the importance for road safety of the consumption of these substances. Alcohol remains the major risk at any age. Young drivers consuming alcohol and cannabis represent a priority target for prevention.

We show experimentally and theoretically that the Lehmann effect recently observed by Yoshioka and Araoka (Nat. Commun., 2018, 9, 432) in emulsified cholesteric liquid crystal droplets under temperature gradients is due to Marangoni flows rather than to the thermomechanical or chemomechanical couplings often invoked to explain the phenomenon. Using colloidal tracers we visualize convection rolls surrounding stationary cholesteric droplets in vertical temperature gradients, while a shift in the position of internal point defects reveals the corresponding inner convection in nematic droplets thermomigrating in a horizontal temperature gradient. We attribute these phenomena to the temperature dependence of the surface tension at the interface between these partially-miscible liquids, and justify their absence in the usual case of purely lyophobic emulsions. We perform a theoretical analysis to help validate this hypothesis, demonstrating the strong dependence of the precession velocity on the configuration of the cholesteric director field.

Diamond-like amorphous carbon (DLC) films have been grown by pulsed-dc plasma-enhanced chemical vapour deposition on silicon wafers, which were previously patterned by means of colloidal lithography. The substrate conditioning comprised two steps: first, deposition of a self-assembled monolayer of silica sub-micrometre spheres (∼300 nm) on monocrystalline silicon (∼5 cm2) by Langmuir–Blodgett technique, which acted as lithography template; second, substrate patterning via ion beam etching (argon) of the colloid samples (550 eV) at different incidence angles. The plasma deposition of a DLC thin film on the nanotextured substrates resulted in hard coatings with distinctly different surface properties compared with planar DLC. Also, in-plane anisotropy was generated depending on the etching angle. The samples were morphologically characterized by scanning electron microscopy and atomic force microscopy. The anisotropy introduced by the texture was evidenced in the surface properties, as shown by the directional dependences of wettability (water contact angle) and friction coefficient. The latter was measured using a nanotribometer and a lateral force microscope. These two techniques showed how the nanopatterns influenced the tribological properties at different scales of load and contact area. This fabrication technique finds applications in the industry of microelectromechanical systems, anisotropic tribological coatings, nanoimprint lithography, microfluidics, photonic crystals, and patterned surfaces for biomedicine.

By combining colloidal lithography and pulsed-DC plasma deposition of diamond-like amorphous carbon films, we have fabricated sub-microstructures that modulate the surface properties of this material. A self-assembled monolayer of silica sub-micron spheres was deposited on monocrystalline silicon, which was patterned either by thermal annealing of the particles or by hole-mask lithography via ion beam etching with argon. The samples showed hemispherical close-packed topographies and micro-pillar networks. The coefficient of friction, measured with a nanotribometer, and the wettability were controlled through this special surface patterning. These structures are suitable for applications requiring protective coatings with large area showing hydrophobic properties.