Chemical characterization is essential to the study of bioactive compounds in natural and biological samples but conventional preparative and analytical techniques are usually time, energy and solvent-intensive, posing environmental and health risks. Supercritical carbon dioxide (CO2) present an eco-friendly alternative due to its interesting physio-chemical properties. Prof. Wests research group has been developing approaches involving supercritical CO2 for two decades, and recently developed an integrated system combining supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) for the on-line extraction and analysis of polar and non-polar bioactive compounds from plants. Although feasible, such coupling is very challenging, especially when targeting compounds with a wide range of polarities. The next step is thus to further improve the developed system and explore its applicability to other samples with different matrices and classes of compounds. Specifically, the use of unified chromatography (UC), an advanced version of SFC, will be investigated to further expand the efficiency and potential scope of the system. Since the interfacing of the two techniques is a major bottleneck preventing the system from reaching its full potential, finding innovative solutions to facilitate the extract transfer from the first to the second dimension is necessary. An important part of this project will thus be devoted to investigating new interface modalities to address the compatibility problems and instrumental issues pertaining to this hyphenation. To boost chromatographic separation power and facilitate structural elucidation, the potential of incorporating multidimensional (mD) separation steps while coupling the system with mass spectrometry (MS) will also be explored, to develop a novel on-line (mD-SFE)-(mD-SFC/UC)-MS system. Finally, the systems utility will be demonstrated through qualitative and quantitative analyses of real-life samples.

In a world constantly seeking to reduce chemicals consumption and pollution all the while researching for new tools to improve food production and combat the spread of infections, the importance of new breakthrough technologies has become crucial. Imagine a technology able to convert efficientlytap water into a rich fertilizer or a powerful antimicrobial. Dream that this technology is also eco-friendly, cost effective and applicable anywhere in the world since it requires only electricity, air and water to operate. This powerful technology is not a fantasy and is the result of the combination of cold plasma (ionized gas) and water aerosol. Plasmas in contact with water can generate species such as nitrates and nitrites or hydrogen oxides and atomic oxygen. Thus plasma-aerosol technology constitute a nitrogen fixation technique or an advanced oxidation technique (depending on the control parameters) that is expected to be free of solvent and long-term residuals and therefore is eco-friendly and sustainable. Nowadays, the lack of knowledge on the mechanisms governing plasma-aerosols systems hinders their optimization and severely limits the full development of their agricultural applications. The objective of PLASMASOL is to bring new insight on plasma-aerosols so to finally unleash the full potential of this technology. The final aim is to pave the way to a new technology that has the potential to become a breakthrough solution in agriculture for the in-situ and on demand production of fertilizers and antimicrobials. No more need of coal or natural gas, no need of complex supply chains or infrastructures. Plasma-aerosol technology could minimize or even eliminate the environmental impact nowadays associated to the production, distribution and storage of agrochemicals.

This research project focuses on the fundamental study of breakdown phenomena in gases at atmospheric pressure in micrometer gap systems. The prediction of gas breakdown in micro-gaps is still a wide topic to explore, since its understanding cannot be explained the classical breakdown theory. This project proposes to investigate the elementary processes involved in the present conditions, in particular the role of electron field emission via tunneling electrons. Several key parameters will be studied such as the electrode geometry, surface materials, gas, pressure, electrical excitation waveform. Advanced experiments will be conducted involving optical laser spectroscopy techniques. The main outcome of this project will support to refine understanding of breakdown in micro-gaps and will unveil substantial fundamental knowledge to explain the deviation of breakdown prediction derived from the scaling Paschen’s law.

The existence of an atmosphere enriched in H and He around the Earth as it formed has often been proposed. One hypothesis suggests that it could have been captured from the gas present in the proto-planetary disk, before its evaporation. Subsequently, a secondary atmosphere would have been degassed or brought in by a late veneer of chondritic/cometary material. Although this model is regularly evoked using giant planets for comparison, there is no geological proof for its existence, except possibly for the neon in the Earth's mantle. While the model has a flaw (mainly relating to chronology, as the gas from the disk is lost in <6 My while the Earth formed over a period of more than 30My), the solar-type neon in the Earth's mantle is an argument for the existence of such a captured atmosphere, which partially dissolved into a magma ocean. A second scenario for a primordial H2/He-rich atmosphere is the degassing of a mantle that contained implanted solar wind. The APATE project aims to study the isotopic composition of neon in the Earth's mantle in order to determine if this composition is the same as that of the nebula or the solar wind material. I will investigate the degassing processes of magmas experimentally and numerically in order to study the isotopic fractionation that occurs during bubble formation and to determine whether the measured neon isotopic composition can provide an accurate composition for the original mantle. The project aims to calculate the amount of neon that can be incorporated into a magma ocean by establishing the atmospheric pressure of the captured atmosphere and by studying the dynamics of the magma ocean. I will also explore the hypothesis involving solar wind irradiation. Using simulations of irradiation, I will identify those conditions under which this model is realistic and its implications for the Earth’s (isotopic/chemical) composition. The origin of light solar volatiles will then be explored by the APATE project.