References of "Malherbe, Cédric"
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See detailA facile and fast electrochemical route to produce functional few-layer graphene sheets for lithium battery anode application
Ouhib, Farid ULg; Aqil, Abdelhafid ULg; Thomassin, Jean-Michel ULg et al

in Journal of Materials Chemistry A (2014), 2(37), 15298-15302

A simple approach for the production of polymer functionalized graphene nanosheets is reported. The resulting polyacrylonitrile chemisorbed on graphene sheets is made of 1 to 2 layers, with a large ... [more ▼]

A simple approach for the production of polymer functionalized graphene nanosheets is reported. The resulting polyacrylonitrile chemisorbed on graphene sheets is made of 1 to 2 layers, with a large majority of graphene single-layers. This novel functionalized graphene exhibits good cycling stability as an anode in Li-ion batteries without a conductive additive or binder. [less ▲]

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See detailPreparations for the use of Raman spectrometers on Mars
Malherbe, Cédric ULg; Ingley, Richard; Hutchinson, Ian B. et al

Conference (2014, October)

Raman spectroscopy has been selected as a non-destructive powerful analytical method for forthcoming planetary exploration. In the context of the upcoming ExoMars and NASA 2020 missions (developed by the ... [more ▼]

Raman spectroscopy has been selected as a non-destructive powerful analytical method for forthcoming planetary exploration. In the context of the upcoming ExoMars and NASA 2020 missions (developed by the European Space Agency, IKI Roscomos and NASA) analysis of the biological and geological terrestrial analogues using laboratory instrumentation is of great importance; especially testing the performance of flight-like operating modes and conditions on the feasibility of flight instruments meeting their science goals. Here we present a set of measurements of terrestrial analogues (among them desert varnishes) selected in preparation for in-situ Raman analysis on Mars. Laboratory instrumentation has been used to fully characterise the samples in addition to being operated in modes consistent with ExoMars RLS instrument flight designs, sample preparation and delivery. We discuss the performance of the spectrometers regarding the detection of the target signatures and their geological context. The impact of instrument operating modes and application of flight instrument sampling philosophy (i.e. spot size, grain size, number of target locations, sample preparation and delivery) on the signal intensity and the limits of detection are also discussed. [less ▲]

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See detailRaman spectroscopy on Mars: identification of geological and bio-geological signatures in Martian analogues using miniaturized Raman spectrometers
Hutchinson, Ian B.; Ingley, Richard; Edwards, Howell G. M. et al

in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences (2014)

The first Raman spectrometers to be used forin situ analysis of planetary material will be launched as part of powerful, rover-based analytical laboratories within the next 6 years. There are a number of ... [more ▼]

The first Raman spectrometers to be used forin situ analysis of planetary material will be launched as part of powerful, rover-based analytical laboratories within the next 6 years. There are a number of significant challenges associated with building spectrometers for space applications, including limited volume, power and mass budgets, the need to operate in harsh environments and the need to operate independently and intelligently for long periods of time (due to communication limitations). Here, we give an overview of the technical capabilities of the Raman instruments planned for future planetary missions and give a review of the preparatory work being pursued to ensure that such instruments are operated successfully and optimally. This includes analysis of extremophile samples containing pigments associated with biological processes, synthetic materials which incorporate biological material within a mineral matrix, planetary analogues containing low levels of reduced carbon and samples coated with desert varnish that incorporate both geo-markers and biomarkers. We discuss the scientific importance of each sample type and the challenges using portable/flight-prototype instrumentation. We also report on technical development work undertaken to enable the next generation of Raman instruments to reach higher levels of sensitivity and operational efficiency. [less ▲]

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See detailMatrix ‐ assisted laser desorption/ionization mass spectrometry and Raman spectroscopy: An interesting complementary approach for lipid detection in biological tissues
Jadoul, Laure ULg; Malherbe, Cédric ULg; calligaris, David et al

in European Journal of Lipid Science and Technology [=EJLST] (2014)

Recently, matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) has emerged as a powerful technique to study the distribution of lipids. However, quantification still remains a ... [more ▼]

Recently, matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) has emerged as a powerful technique to study the distribution of lipids. However, quantification still remains a challenge because the MALDI signal is strongly affected by ion suppression effects. On the contrary, Raman spectroscopy is recognized as a non‐destructive analysis method and spectral images can also be acquired. The combination of these two techniques was applied for lipids detection in tissue sections. In MALDI, two lipids families (glycerophosphocholine, PC; gycerophosphoethanolamine, PE), three MALDI matrices (1,5‐diaminonapthalene, 1,5‐DAN; 2,5‐dihydroxybenzoic acid, 2,5‐DHB; a‐4‐hydroxicinammic acid, CHCA), and various mixtures of lipids were investigated. The nature of the lipid, as well as the nature of the matrix and the composition of the sample influences the signal of a given lipid. In Raman, despite a strong overlap with the spectrum of the native tissue, an intensity profile constructed along the diameter of the section clearly shows that the signature of one given lipid (a glycerophosphocholine) can be detected on a doped biological sample. [less ▲]

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See detailDetermination of the Al2O3 content in NaF-AlF 3-CaF2-Al2O3 melts at 950 °c by raman spectroscopy
Malherbe, Cédric ULg; Eppe, Gauthier ULg; Gilbert, Bernard ULg

in Analytical Chemistry (2014)

Thein situ control of the chemical composition of industrial aluminum smelter is a challenge mainly for physicochemical reasons: high temperature, high surrounding electromagnetic field, and the highly ... [more ▼]

Thein situ control of the chemical composition of industrial aluminum smelter is a challenge mainly for physicochemical reasons: high temperature, high surrounding electromagnetic field, and the highly corrosive molten salt electrolyte to deal with. In previous works, we proposed that Raman spectroscopy is a method of choice that could be adapted to real smelters. The laboratory study presented here relies on reproducible Raman spectra recorded on molten mixtures whose compositions are identical to those used during the production of aluminum. A normalization procedure for the Raman spectra is proposed based on the equilibria taking place in the bath. In addition, we discuss two quantitative models to determine the alumina content from the Raman spectra of the molten NaF−AlF3−CaF2−Al2O3 electrolytes. Univariate and multivariate approaches are applied to determine both theCOx (alumina content) and the CR (NaF/AlF3 molar ratio) by Raman spectroscopy without referring to an additional internal reference of intensity. The procedure was successfully tested and validated on industrial samples. [less ▲]

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See detailDevelopment of an analytical method to determine the composition of cryolitic baths used in the Hall-Heroult process, by Raman spectroscopy, at 1000°C
Malherbe, Cédric ULg

Doctoral thesis (2013)

Worldwide metallic aluminium production involves the Hall-Héroult process where the metal is electro-deposited from aluminium oxide solubilised in a molten NaF-AlF3-CaF2 mixture at around 950°C. The ... [more ▼]

Worldwide metallic aluminium production involves the Hall-Héroult process where the metal is electro-deposited from aluminium oxide solubilised in a molten NaF-AlF3-CaF2 mixture at around 950°C. The cryolitic melt is conveniently characterised by both the molar NaF/AlF3 ratio and the Al2O3 content. Nowadays the Hall-Héroult process remains the more economically efficient process even if it still suffers from a high consumption of energy. In particular the overvoltage required by the electrolysis is strongly dependent on the melt composition, especially regarding the Al2O3 content. Controlling the industrial baths composition during the process is therefore critical to reduce the energy loss. Unfortunately there is, up to now, no in situ direct analytical method to do so. Considering our experience in the study of such highly corrosive media by Raman spectroscopy, that technique has been applied to directly determine the melt composition. Three sets of reference spectra are considered in this study, each of them recorded with a different setup. The employed setups were developed to reach progressively, at the laboratory scale, a design that is suitable for a plant application. Eventually, a high quality spectrum can be recorded by the top of the melt, in less than 20 seconds. The employed apparatus is found to influence significantly the shape and quality of the spectra, and consequently their involvement in the quantification. A complex digital treatment of the spectral data acquired is necessary because all Raman bands of interest strongly overlap and some are situated close to the Rayleigh decay. Two main quantitative procedures for the melt composition determination are studied. The first one, the AutoAnalysis procedure, developed in the past and adapted here to the new data, gives reliable predictive results for both the NaF/AlF3 molar ratio and the alumina content. They can be determined with an absolute deviation of 0.06 molar ratio unit and 0.5 wt% respectively. However, the intensity normalisation, required for comparing the intensities of different spectra, relies on the Rayleigh decay that is likely to change with the experimental conditions in the plants. In our second quantitative procedure, the NormaAnalysis procedure, the intensity normalisation is based on the equilibria taking place in the melt. Since those equilibria do no differ with the experimental setup, the NormaAnalysis procedure can be imported to the industrial field. The predicted composition is also evaluated with a good precision: the NaF/AlF3 molar ratio and the alumina content can be determined with an absolute deviation of 0.08 cryolitic ratio unit and 0.3 wt% respectively. It is concluded that the composition of the melt can now be determined with our NormaAnalysis procedure, from a single Raman spectrum, recorded with a Raman apparatus exportable for an in situ measurement on the industrial cells. [less ▲]

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See detailDevelopment of a quantitative approach to measure phospholipids in dried drops by Raman spectroscopy
Malherbe, Cédric ULg; Jadoul, Laure ULg; Gilbert, Bernard ULg et al

Poster (2013, May 24)

Phospholipids, PL, such as the phosphatidylcholine PC(18:0/18:1), play a role in the structure of living cells and are suspected to be part of the development of some diseases, for example cancers. Mass ... [more ▼]

Phospholipids, PL, such as the phosphatidylcholine PC(18:0/18:1), play a role in the structure of living cells and are suspected to be part of the development of some diseases, for example cancers. Mass spectrometry enables the structural analysis of PL in complex biological media but imaging mass spectrometry by MALDI-MS is rather limited for quantification purposes. Complementarily, Raman spectroscopy as a non invasive and non destructive method is a potential candidate to quantify and visualise the spatial distribution of the PL by molecular imaging. Unfortunately, the lack of specific chemical function in PL, compared to others biomolecules, limits the use of Raman spectroscopy in the identification process of those PL in complex biological samples. The results presented here belong to a first study of the application of the Raman analyses on dried residues of PL and mice brain tissue performed in the lab. [less ▲]

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See detailDirect determination of the NaF/AlF3 molar ratio by raman spectroscopy in NaF-AlF3-CaF2 melts at 1000° C
Malherbe, Cédric ULg; Gilbert, Bernard ULg

in Analytical Chemistry (2013)

For the last 40 years, Raman spectroscopy has been very useful in investigating the structure of corrosive molten salts, such as the cryolite-based melts widely used as electrolyte in the Hall-Heroult ... [more ▼]

For the last 40 years, Raman spectroscopy has been very useful in investigating the structure of corrosive molten salts, such as the cryolite-based melts widely used as electrolyte in the Hall-Heroult process. Even if this process remains the most economically efficient for metallic aluminum electro-production, it suffers from a high energy loss, which is dependent on the melt composition. Therefore, controlling the chemical composition of the electrolyte is essential. The present paper proposes to apply Raman spectroscopy for the direct determination of the NaF-AlF3 molar ratio in NaF-AlF3-CaF2-based melts. Despite the experimental difficulties, a calibration curve based on equilibria taking place in the melt has been developed and the procedure has been successfully compared to industrial samples of known compositions. The possible exportation of the laboratory scale procedure to an industrial environment application for the control of the Hall-Heroult process is finally discussed. [less ▲]

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See detailLithium transition metal (Ti, Nb, V) oxide mesoporous thin films: contrasting results when attempting direct synthesis by evaporation-induced self assembly
Caes, Sébastien ULg; Malherbe, Cédric ULg; Krins, Natacha ULg et al

in Microporous and Mesoporous Materials (2013), 172

This work investigates the possibility to prepare mesoporous thin films of Li-Ti, Li-Nb, Li-Nb-V and Li-V oxides through a direct sol-gel EISA route by dissolving a lithium salt in the precursor solution ... [more ▼]

This work investigates the possibility to prepare mesoporous thin films of Li-Ti, Li-Nb, Li-Nb-V and Li-V oxides through a direct sol-gel EISA route by dissolving a lithium salt in the precursor solution. Experimental conditions involve a hydrolysis molar ratio H2O/TM ~10 (TM = Ti,Nb,V) and the common Pluronic structuring agent P123 (EO20-PO70-EO20). Systematic formation of lithium-containing oxides as first-crystallizing phases points to a significant intermixture of lithium and transition metal ions in the inorganic network. In the case of Ti-based and Nb-based oxide films, addition of lithium to the precursor solution is compatible with the formation of amorphous mesoporous films at 350°C. On the contrary, addition of lithium has a detrimental effect on the notoriously difficult formation of vanadium-based mesostructured films: even when replacing half of the vanadium by niobium as a stabilizer, formation of mesostructured films has not been possible in the investigated range of experimental conditions. [less ▲]

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See detailDevelopment of a quantitative approach to measure phospholipids in dried drops by Raman spectroscopy
Malherbe, Cédric ULg; Jadoul, Laure; Gilbert, Bernard ULg et al

Poster (2012, October)

We present here the results obtained during our tentative to analyse quantitatively dried drops of phospholipidic solutions by Raman spectroscopy. Drops of different solutions of phospholipid were deposed ... [more ▼]

We present here the results obtained during our tentative to analyse quantitatively dried drops of phospholipidic solutions by Raman spectroscopy. Drops of different solutions of phospholipid were deposed onto different material supports. The spots were then analyses by confocal Raman microspectroscopy. Experimental settings have been optimised and the analysis of the intensity profile of the Raman signal inside the spot allows the establishment of a calibration curve for the determination of the phospholipids amount within a 1 µL solution. [less ▲]

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See detailOnline monitoring of heterogeneous polymerizations in supercritical carbon dioxide by Raman spectroscopy
Grignard, Bruno ULg; Gilbert, Bernard ULg; Malherbe, Cédric ULg et al

in Chemphyschem : A European Journal of Chemical Physics and Physical Chemistry (2012), 13(11), 2666-2670

A novel setup is described to monitor the kinetics of homogeneous and heterogeneous reactions online using Raman spectroscopy under high pressure. The arrangement is based on a high-pressure reactor ... [more ▼]

A novel setup is described to monitor the kinetics of homogeneous and heterogeneous reactions online using Raman spectroscopy under high pressure. The arrangement is based on a high-pressure reactor equipped with a sapphire window in combination with a mobile probe that allows the collection of the back-scattered Raman signal at 360°. [less ▲]

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See detailDetermination of the composition of cryolitic melts involved in the Hall-Heroult process by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Conference (2012, August)

Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of the molar NaF/AlF3 ratio and the Al2O3 content, we have proposed in ... [more ▼]

Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of the molar NaF/AlF3 ratio and the Al2O3 content, we have proposed in the past to apply that technique to the direct determination of the melt composition . Recent instrumental developments on CCD based spectrometers have made the proposed method more feasible. This presentation will first demonstrate that, employing an updated instrument provided with new optical filters and a more sensitive CCD detector, better quality spectra are obtained. Afterward, new results relevant to the development of our analytical method for the direct determination of the molar NaF/AlF3 ratio and the Al2O3 content in cryolitic melt will be discuss. Different aspects of the calculation procedure will be illustrated:  Estimation and subtraction method of the Rayleigh decay from melt spectra;  Development of an internal normalisation procedure based on equilibria in the melt and assisted by home-made software;  Establishment of calibration curves for the determination of the molar ratio NaF/AlF3 in the melt;  Establishment of calibration curves for the determination of oxide content in the melt;  Overall procedure for the composition determination. [less ▲]

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See detailRaman spectroscopy, a tool for biochemical applications
Malherbe, Cédric ULg

Scientific conference (2012, April 17)

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See detailCharged poly(D,L-lactide) nanofibers: towards customized surface properties
Croisier, Florence ULg; Aqil, Abdelhafid ULg; Malherbe, Cédric ULg et al

in Macromolecular Symposia (2011), 309/310(1), 20-27

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP ... [more ▼]

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP process. In a basic medium, negative charges were therefore revealed on fiber surface. By deposition of positively charged particles or polyelectrolytes, surface properties of the fibers could be tailor-made for a specific application. This versatile method can, for example, be applied to the preparation of new biomedical scaffolds. [less ▲]

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See detailDevelopment of an analytical method to determine the cryolitic bath composition by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Poster (2010, April 23)

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial ... [more ▼]

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial melt is composed mostly of cryolite (Na3AlF6) and AlF3 and is characterized by the molar NaF/AlF3 ratio, named cryolitic ratio (CR). It turns out that the bath composition is critical: for instance, it has been shown that a small change in the Al2O3 content leads to a great change in the overvoltage required for the electrolysis. Therefore controlling the melt composition is very important in order to reduce the energy lost. Unfortunately no in situ analytical method allows studying the composition of the melt yet. Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of both the CR and the Al2O3 content, we have proposed in the past to apply that technique to the direct determination of the melt composition. Despite the CR could be well evaluated in the lab, experimental problems however made the practical application difficult. The purpose of this presentation will be to show the new results obtained on an updated instrument: - Spectra are recorded in 20 s or less with a higher quality than before. - The previously developed home-made software was adapted to the updated instrument and various spectra analysis procedures are under study. - A procedure to prepare reference samples was also developed taking into account the homogeneity problems that have been met. - The slopes of the alumina calibration curves are depending on the bath CR, in confirmation of our previous results. - The new results are compared with the previous ones. It will be concluded that Raman spectroscopy is indeed becoming a suitable technique for developing an analytical method to determine the composition of industrial cryolitic melts. [less ▲]

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See detailThe Hydrogen Electrode in Ionic Liquids: Acidity Measurements and Titrations
Robert, Thierry ULg; Malherbe, Cédric ULg; Magna, lionel et al

Poster (2010, March)

The acidity level in ILs containing acid was first determined using the Hammett acidity function (H0)1-2 in our laboratory. It was demonstrated that this attainable acidity, extending from -3 to -8, is ... [more ▼]

The acidity level in ILs containing acid was first determined using the Hammett acidity function (H0)1-2 in our laboratory. It was demonstrated that this attainable acidity, extending from -3 to -8, is exclusively depending of the nature of anion and follow the order: PF6 > BF4 > NTf2 > OTf. Nevertheless, the Hammett acidity function is an apparent function in this media and must then be corrected for. Consequently, in a second step, we tried to evaluate directly the proton activity from the determination of a potentiometric acidity function (R0) based on the extrathermodynamic Strehlow assumption.3 Therefore, the equilibrium potential of the H+/H2 couple was measured with an hydrogen electrode versus the ferricinium/ferrocene couple for which the potential is considered as independent of the solvent. [less ▲]

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See detailAn analytical method to determine the composition of cryolitic melts involved in the Hall-Heroult process by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Poster (2010, March)

The Hall-Héroult process involves the metallic aluminium production from electroreduction of aluminium oxide in cryolitic melt (mostly composed of cryolite and aluminium fluoride) around 1000°C. In order ... [more ▼]

The Hall-Héroult process involves the metallic aluminium production from electroreduction of aluminium oxide in cryolitic melt (mostly composed of cryolite and aluminium fluoride) around 1000°C. In order to reduce the energy loss during this process, controlling the melt composition turns out to be critical. Unfortunately, no in situ analytical method allows measuring the melt composition yet. Since the Raman spectrum of the melt depends on both the cryolitic ratio (molar NaF/AlF3 ratio, CR) and the aluminium oxide content, our laboratory proposed in the past to apply Raman spectroscopy for direct melt composition determination by recording the spectrum from the top. However, experimental problems made the practical application difficult. Nowadays, the method is becoming more feasible because of new instrumental developments such as new sensitive CCD, fiber optics and new optical filters. [less ▲]

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