Pierre Bernhardt

Tunable Generation and Adsorption of Energetic Compounds in the Vapor Phase at Trace Levels: A Tool for Testing and Developing Sensitive and Selective Substrates for Explosive Detection

Among various methods for landmine detection, as well as soil and water pollution monitoring, the detection of explosive compounds in air is becoming an important and inevitable challenge for homeland security applications, due to the threatening increase in terrorist explosive bombs used against civil populations. However, in the last case, there is a crucial need for the detection of vapor phase traces or subtraces (in the ppt range or even lower). A novel and innovative generator for explosive trace vapors was designed and developed. It allowed the generation of theoretical concentrations as low as 0.24 ppq for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in air according to Clapeyron equations. The accurate generation of explosive concentrations at subppt levels was verified for RDX and 2,4,6-trinitrotoluene (TNT) using a gas chromatograph coupled to an electron capture detector (GC-ECD). First, sensing material experiments were conducted on a nanostructured tungsten oxide. The sensing efficiency of this material determined as its adsorption capacity toward 54 ppb RDX was calculated to be five times higher than the sensing efficiency of a 54 ppb TNT vapor. The material sensing efficiency showed no dependence on the mass of material used. The results showed that the device allowed the calibration and discrimination between materials for highly sensitive and accurate sensing detection in air of low vapor pressure explosives such as TNT or RDX at subppb levels. The designed device and method showed promising features for nanosensing applications in the field of ultratrace explosive detection. The current perspectives are to decrease the testing scale and the detection levels to ppt or subppt concentration of explosives in air.

A Novel Microfluidic Formaldehyde Microanalyser for Continuous Real-Time Monitoring in Indoor Air: Analytical Development and Validation

Formaldehyde is a major and harmful pollutant of indoor air due to its multiple sources and its [...]

Decomposição Catalítica da Hidrazina sobre Irídio Suportado em Compósitos à base de Nanofibras de Carbono para Propulsão Espacial. Testes em Condições Reais

The aim of this work is to present the catalytic performance of iridium supported on carbon nanofibers with macroscopic shaping in a 2 N hydrazine microthruster placed inside a vacuum chamber in order to reproduce real-life conditions. The performances obtained are compared to those of the commercial catalyst Shell 405. The carbon-nanofiber based catalyst showed better performance than the commercial catalyst from the standpoint of activity due to its texture and its thermal conductivity.

Carbon Nanofiber Composite as a Catalytic Hydrazine Decomposition Support for Satellite Propulsion

The aim of this work is to determine the catalytic performance characteristics of iridium on a carbon nanofiber support with macroscopic shaping in the catalytic decomposition of hydrazine. The obtained performance characteristics obtained are compared with those of a commercial catalyst, Shell 405. Catalytic experiments are carried out in a 2 N microthruster placed inside a vacuum chamber in order to reproduce natural conditions.