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Phase equilibrium during the synthesis of LiNi0.46Mn1.54O4: comprehensive X-ray & neutron powder diffraction study
No full textInternational audienceA combination of synchrotron X-ray powder diffraction (SXRPD) and neutron powder diffraction (NPD) is used to investigate phase equilibrium during the synthesis of LiNi0.46Mn1.54O4 (LNMO) powders from a reagent mixture. A Li-deficient disordered LNMO begins to form at T ≈ 460 °C and as the temperature increases, oxygen release triggers the formation of impurity phases. Advanced structural characterization of quenched LNMO samples, along with in situ SXRPD experiments, reveals that a layered oxide impurity crystallizes between 700 °C and 900 °C. At temperatures of 900 °C and above, this impurity phase transforms into a rock-salt type one, while a Li-rich layered oxide impurity also emerges. This leads to the coexistence of three phases at T ≥ 900 °C: LNMO spinel, rock salt, and Li-rich layered oxide. These transformations affect significantly the composition of the targeted LNMO spinel phase, which highlights the challenges in achieving phase purity with the desired stoichiometry in this complex system. The findings provide valuable insights for optimizing the LNMO synthesis so as to prepare high-performance positive electrode materials
Creation of NV centers and control of their location in very thin single- crystal diamond films
No full textInternational audienceDiamond is an outstanding material for a wide range of applications, including optics, electronics, biomedical field, mechanics and quantum technologies, due to the unique combination of its remarkable physical and chemical properties. Over the last few years, a Distributed Antenna Array (DAA) microwave system, composed of 16 microwave plasma sources arranged in a 2D matrix, has been used for the deposition of single-crystal diamond (SCD) layers by operating with H2/CH4/CO2 and H2/CH4/O2 gas mixture. One of the interests is its low working pressure ( 300 cm2) at very low growth rates (< 100 nm.h-1) [1]. The latter is very useful to control the thickness and therefore the position of particular defects inside the diamond layers, such as colour centres, which are particularly interesting for quantum technology applications [2-3]. For instance, nitrogen-vacancy (NV) centres could be localised with a high precision within the diamond film.In this work, we successfully synthesize N-doped SCD films of ~150 nm-thick (10 times thinner than in previous achievements [1]) using the DAA microwave reactor, by adding N2 to the initial gas mixture. Combined with relevant post-treatments, such as helium ion implantation and annealing, it has proved possible to localize NV centres in very thin layers of around 50 nm, covered with a thin encapsulation layer of pure SCD deposited in the DAA system. This process for localizing the NV centres is compared to the implantation of SCD intrinsic layers achieved in the DAA reactor with N2+ ions, especially in terms of NV-/NV0 photoluminescence intensities and coherence time (T2*) .References1.C. Mahi et al., Synthesis of single crystal diamond films using a distributed antenna array microwave system. SBDD XXVIII, Feb 2024, Hasselt, Belgium.2.L. Rondin, et al. Rep. Prog. Phys. 77 (2014) 056503 3.J. Achard et al. J. Phys. D: Appl. Phys. 53 (2020) 31300
Acoustic Positioning for Deep Sea Neutrino Telescopes with a System of Piezo Sensors Integrated into Glass Spheres
No full textInternational audiencePosition calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000m. It comprised nearly 900 glass spheres with 432mm diameter and 15mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such - otherwise empty - glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with mm/s and a slow (late) one with mm/s. Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes
From gem ‐Dichlorocyclobutenones to Cyclobutenols: Unveiling a Ruthenium‐Catalyzed Allylic Reduction‐Asymmetric Transfer Hydrogenation Cascade
No full textInternational audienceCyclobutenones constitute an appealing class of substrates in catalytic asymmetric transformations leading to diversely substituted enantioenriched four‐membered carbocycles, which are eliciting a growing interest in medicinal chemistry. Whilst several synthetically useful enantioselective conjugate addition reactions have been reported, the catalytic enantioselective reduction of the carbonyl group of simple cyclobutenones remains an elusive transformation. Herein, we disclose the discovery of a novel allylic reduction‐asymmetric transfer hydrogenation cascade, catalyzed by a Noyori‐Ikariya ruthenium complex, from readily available gem ‐dichlorocyclobutenones, leading to 2‐chlorocyclobutenols with high optical purities, which can be engaged in postfunctionalization reactions enabling access to substituted four‐membered rings
Développement de systèmes microfluidiques économiques pour des applications bioanalytiques
No full textThis thesis was conducted as part of a joint supervision between the Universidade Federal de Goiás (Goiânia, Brazil) and Chimie ParisTech PSL. Initiated in Brazil at the onset of the pandemic, the work developed during the Ph.D. at the Brazilian institution focused on developing LAMP-based methodologies for COVID-19 diagnosis. Loop-mediated isothermal amplification (RT-LAMP) was used to create a simple and low-cost test during the COVID-19 pandemic. This test was implemented at the point of care in an overwhelmed hospital where standard tests were not feasible, providing rapid and accurate diagnoses. Additionally, we proposed a non-invasive tracking method based on RNA extracted from the saliva of essential workers during the pandemic, which proved practical and effective for frequent testing. The preliminary transposition of this methodology to a paper-based platform showed promising results for real-time monitoring of infections, particularly SARS-CoV-2, at the point of care. Within the scope of the cotutella, subsequent work was carried out in the French laboratory to develop and optimize a paper-based platform for protein isoelectric focusing, aiming to integrate proteomic analysis steps into a microdevice. In this thesis, we developed diagnostic systems for biomolecules applied or applicable at the point of care. For protein analysis, isoelectric focusing on a paper-based platform allowed precise and reproducible protein separation, including in real samples, with acceptable resolution and efficiency. This system represents a significant step forward in a broader project aimed at integrating all proteomic steps into a single chip. The successful development of biomolecule analysis methods prioritizing cost-effectiveness, speed, and simplicity highlights the potential of paper as a platform for these diagnostic tests. Paper proved to be a suitable and accessible platform for conducting these tests, emphasizing its potential in resource-limited settings.Cette thèse a été efectuée dans le contexte d'une co-tutelle entre l'Université Fédérale de Goias (Goiania, Brésil) et Chimie ParisTech PSL. Elle a débuté au Brésil, au début de la pandémie, ce qui a très fortement orienté le travail dans le laboratoire brésilien. Loop mediated isothermal amplification a été utilisée pour créer un test simple et économique pendant la pandémie de COVID-19. Nous avons mis en oeuvre ce test au point de soins dans un hôpital submergé par le nombre de patients, où les tests standards n'étaient pas réalisables. Notre test a fourni des diagnostics rapides et précis. De plus, nous avons proposé une méthode de dépistage non invasive basée sur l'ARN extrait de la salive des travailleurs essentiels durant la pandémie, qui s'est révélée à la fois pratique et efficace pour des tests fréquents. La transposition préliminaire de cette méthodologie à une plateforme en papier a montré des résultats prometteurs pour le suivi en temps réel des infections, en particulier celles du SARS-CoV-2, au point-of-care. Dans le cadre de la co-tutelle, des travaux ont été effectués ensuite dans le laboratoire français pour le développement et l'optimisation d'une plateforme papier pour la focalisation isoélectrique des protéines, en vue d'intégrer toutes les étapes de l'analyse protéomique dans un microdispositif. Dans ce travail, nous avons développé des systèmes de diagnostic pour les biomolécules appliqués ou applicables au point-of-care. Nous avons mis le focalisation isoélectrique sur une plateforme à base de papier, obtenant une séparation des protéines précise et reproductible, y compris dans des échantillons réels, avec une résolution et une efficacité acceptables. Ce système représente une étape supplémentaire dans un projet plus vaste visant à intégrer toutes les étapes protéomiques sur une seule puce. Le développement réussi de méthodes d'analyse des biomolécules, privilégiant l'économie, la rapidité et la simplicité, met en lumière le potentiel du papier en tant que plateforme pour ces tests diagnostiques. Le papier s'est avéré être une plateforme adaptée et accessible pour la réalisation de ces tests, soulignant son potentiel dans des contextes à ressources limitées
Electromediated Alcohol-Based Passerini-Type Reaction
No full textInternational audienceAn electrochemical variant of the alcohol-based oxidative Passerini reaction is reported here. It relies on an indirect anodic oxidation process followed by a three-component coupling, in which TEMPO serves as a key redox mediator. This electrochemical approach permits to operate without the need for a metal catalyst nor oxygen atmosphere and allows the use of nonactivated alcohols as reaction partners. It could be applied to the preparation of good variety of α-acyloxy-carboxamides in yields ranging from 24% to 80%
Growth, structure and optical characterization of new Pr3+-doped LaGaGe2O7 and LaGa0.6Al0.4Ge2O7 single crystals
No full textInternational audienceIn this work, a new crystal belonging to the germanate family: LaGaGe2O7 (or LGGO) doped with trivalent Praseodymium (Pr) ion is studied. We report the first single crystal growth of this material using the Czochralski method. The spectroscopic properties including absorption and emission cross-sections of praseodymium in this new matrix are measured, as well as the refractive index along the dielectric axes. This material exhibits very high emission cross sections of 38, 20, and 16 10−20 cm2 at 746 nm, 646 nm and 620 nm, respectively. Some persistent luminescence is observed in Pr:LGGO after UV irradiation at 254 nm. To reduce the phenomenon, the solid solution LaGa1-xAlxGe2O7 (0 ≤ x ≤ 1) is considered. Thermoluminescence experiments show that a substitution of 40 % of gallium by aluminium in the crystal structure allows to suppress this persistent luminescence phenomenon
Uniform Polymer Microspheres by Photoinduced Metal‐Free Atom Transfer Radical Precipitation Polymerization
No full textInternational audienceHerein, a photoinduced method is introduced for the synthesis of highly cross-linked and uniform polymer microspheres by atom transfer radical polymerization (ATRP) at room temperature and in the absence of stabilizers or surfactants. Uniform particles are obtained at monomer concentrations as high as 10% (by volume), with polymers being exempt from contamination by residual transition metal catalysts, thereby overcoming the two major longstanding problems associated with thermally initiated ATRP-mediated precipitation polymerization. Moreover, the obtained particles have also immobilized ATRP initiators on their surface, which directly enables the controlled growth of densely grafted polymer layers with adjustable thickness and a well-defined chemical composition. The method is then employed successfully for the synthesis of molecularly imprinted polymer microspheres
Terms of Latin origin relating to sample characterization (IUPAC Technical Report)
No full textInternational audienceAbstract The use of Latin origin terms, relevant for sample characterization modalities, is described with a focus on samples under controlled conditions, samples within devices, and samples during physico-chemical evolution. The terms in vitro , in vivo , in situ , ab initio , in silico , post mortem , ex situ , posthumous , in vacuo , (in) operando , post facto , and ex post facto , as used in the scientific literature, are considered. Uses of the Latin origin terms in situ , extra situm , in operando , in vivo , in vacuo , in vitro , extra vivum , post facto and ex post facto , ab initiis , computatro , and post mortem are discussed. It is suggested that these terms are to be used without hyphenation and that all Latin derived terms are set in italic font
Long-Life Pillar[5]quinone Cathode for Aqueous Zinc-Ion Batterie
No full textInternational audienceAqueous zinc ion batteries (ZIBs) are currently gaining a significant amount of attention as a low-cost and high safety energy storage option. While mostly inorganic structures are used as cathode materials in aqueous zinc batteries, these materials undergo structural degradation, therefore, alternative organic cathodes are expected to be developed to replace inorganic materials in aqueous zinc ion batteries (AZIBs). In this work, pillar[5]quinone (P5Q) is used as a cathode in AZIBs for the first time. Besides investigating the charge storage mechanism and interfacial property evolution of P5Q by various ex situ analyses, electrochemical quartz crystal microbalance (EQCM) and density functional theory (DFT) demonstrates both Zn 2+ and H + incorporation. The P5Q exhibits >99% Coulombic efficiency through 10000 cycles at ultra-fast (500 C) current density, yielding a capacity value of approximately 120 mAh g -1 at the end of the cycle. When the current density is changed from 500 C to 120 C, an initial discharge capacity of approximately 182 mAh g -1 is achieved, demonstrating outstanding performance with over 80% capacity retention for the subsequent 7000 cycles