Solenn Reguer

The unique properties and application possibilities of two‐dimensional (2D) materials motivate the exploration of different nanolaminated compounds. Here, by using a molten salt approach, we selectively etch Ti ₂ InB ₂ with ZnCl ₂ to produce a multilayer (ml) Ti ₂ B ₂ Cl _x MBene. Upon etching, indium atoms are completely removed from the precursor and replaced by chlorine surface terminations with a coverage of 1.1 < x < 1.4. Further, in situ x‐ray diffraction indicates a direct biphasic transformation from Ti ₂ InB ₂ to ml‐MBene, with no signs of intermediate phase formation. A computational framework based on density functional theory further corroborates these experimental observations by showing a negative reaction free energy for the formation of ml‐MBene, favourable over all competing processes. In addition, A‐element substitution into the 3D Ti ₂ ZnB ₂ phase is predicted to be endergonic, consistent with the absence of experimental evidence for its formation. Initial Li‐ion battery performance evaluation showed a stable discharge capacity similar to or better than MAX phases and other borides. Altogether, the theoretical framework combined with materials synthesis and characterization provides a general approach for 2D materials development, for further expansion of the family of 2D materials.

Blue pigments are absent in Palaeolithic art. This has been ascribed to a lack of naturally occurring blue pigments or low visual salience of these hues. Using a suite of archaeometric approaches, the authors identify traces of azurite on a concave stone artefact from the Final Palaeolithic site of Mühlheim-Dietesheim, Germany. This represents the earliest use of blue pigment in Europe. The scarcity of blue in Palaeolithic art, along with later prehistoric uses of azurite, may indicate that azurite was used for archaeologically invisible activities (e.g. body decoration) implying intentional selectivity over the pigments used for different Palaeolithic artistic activities.

Skin reactions are well described complications of tattooing, usually provoked by red inks. Chemical characterizations of these inks are usually based on limited subjects and techniques. This study aimed to determine the organic and inorganic composition of inks using X-ray fluorescence spectroscopy (XRF), X-ray absorption spectroscopy (XANES) and Raman spectroscopy, in a cohort of patients with cutaneous hypersensitivity reactions to tattoo. A retrospective multicenter study was performed, including 15 patients diagnosed with skin reactions to tattoos. Almost half of these patients developed skin reactions on black inks. XRF identified known allergenic metals – titanium, chromium, manganese, nickel and copper – in almost all cases. XANES spectroscopy distinguished zinc and iron present in ink from these elements in endogenous biomolecules. Raman spectroscopy showed the presence of both reported (azo pigments, quinacridone) and unreported (carbon black, phtalocyanine) putative organic sensitizer compounds, and also defined the phase in which Ti was engaged. To the best of the authors' knowledge, this paper reports the largest cohort of skin hypersensitivity reactions analyzed by multiple complementary techniques. With almost half the patients presenting skin reaction on black tattoo, the study suggests that black modern inks should also be considered to provoke skin reactions, probably because of the common association of carbon black with potential allergenic metals within these inks. Analysis of more skin reactions to tattoos is needed to identify the relevant chemical compounds and help render tattoo ink composition safer.

Thanks to important advances in synthesis techniques, a wide collection of bimagnetic core–shell nanoparticles with tunable properties was reported in the literature. Such nanoparticles may combine two phases with different intrinsic magnetic properties (magnetization, anisotropy, coercive field, etc.). Core–shell structures with large interfaces usually favor efficient exchange coupling between both phases that may result in the enhancement of the effective magnetic anisotropy energy and of the coercive field. In this context, the chemical composition and the crystal structure of the core/shell interface in nanoparticles are crucial parameters to modulate efficiently their magnetic properties. Here, we report on the solvent mediated thermal annealing of Fe_3−δO₄@CoO nanoparticles in a high boiling point solvent. The structure of nanoparticles was investigated before and after thermal annealing by advanced characterization techniques such as high resolution transmission electron microscopy (HR-TEM), X-ray absorption spectroscopy (XAS), X-ray magnetic circular dichroism (XMCD) and diffraction anomalous near edge structure (DANES). The combination of DANES and XAS/XMCD allowed studying the cationic distribution in spinel and wüstite crystal structures as a function of site occupancy and oxidation state. To the best of our knowledge, it is the first time that DANES is performed to quantitatively investigate the chemical composition of biphasic metal oxide nanoparticles. Hence, we have investigated precisely the chemical composition of the spinel phase and that of the wüstite phase. Besides the partial solubilisation of the CoO shell observed by HR-TEM, thermal annealing favors the formation of a thicker intermediate Co-doped ferrite layer at the spinel/wüstite interface. Such significant modifications of the core@shell structure markedly influence interfacial coupling phenomena between the core and the shell, hence offering wide perspectives towards nanoparticles with tunable magnetic properties for a variety of applications.

Despite the incidence of breast cancer among women, mammography and anatomopathology investigations are still the gold standard method for preventive screening and diagnosis. Several criteria are used to diagnose precisely the severity of the pathology like the distribution and shape of breast microcalcifications (BMCs). However, the link between the different chemical phases of BMCs and the cancer stage remains unclear. As BMCs physicochemical speciation has the potential to help clinicians during their diagnosis, this study aims to propose a methodology using advanced spectroscopical analysis techniques to finely characterize BMCs and uncover the relationship between mineralization processes and breast cancer. A state of the art in the domain is first proposed to highlight the role of BMCs and the importance of extensive analytical analysis using electron microscopy and vibrational techniques. Secondly, a detailed methodology for BMCs multiscale analysis is proposed and the relevance of each technique illustrated through the study of a biopsy from a patient suffering of an infiltrating low-grade ductal carcinoma: scanning electron microscopy analysis was used for the morphological description of BMCs, infrared micro and nanospectroscopy techniques for their chemical speciation at the micrometric and sub-micrometric scales.

This contribution aims to define an analysis procedure for abnormal deposits in human tissues starting from in vivo characterization, down to the nanoscale using major instrumentation. Such an integrated approach is based on recent literature, but particularly on our research over the last twenty years on pathological calcifications. To this end, we begin by describing four successive analytical steps, on the injury site or physician’s surgery, at the hospital, at a typical physicochemical laboratory, and finally at a large scale (possibly multinational) facility. For the first step, we present various techniques which can be implemented on portable instruments. For the second step, commercial analytical setups are used. In a physicochemical laboratory, prototype or commercial setups are used and finally on large scale instruments, characterization techniques with better spatial resolution and/or higher sensitivity or techniques specific to synchrotron radiation are employed.

Although numerous pathologies are associated with abnormal skin deposits, these remain poorly described, as accurate characterization continues to present a challenge for dermatologists. Their submicrometer size as well as their diverse chemistry require various characterization tools. We aim to exemplify characterization of endogenous and exogenous skin deposits in some selected skin diseases using different physico-chemical techniques. We begin with a presentation of selected diseases associated with skin deposits. We then present those of our results which show their variety of structure, location and chemical composition, obtained with various tools: Field Emission Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, X-ray fluorescence, vibrational spectroscopies, as well as techniques specific to synchrotron radiation. Our results constitute a real opportunity to improve diagnosis, and to understand the pathogenesis of many skin diseases, and opportunities for therapeutic intervention.

XANES spectroscopy, which uses synchrotron radiation as a probe, offers substantial information about the local structure of biological samples, encompassing those without long range order such as Pt anticancer molecules, and nanometre scale or amorphous particles of calcium phosphate. Its subcellular spatial resolution, as well as its capacity to operate at room temperatures and pressures represent major advantages for medical research. Moreover, paraffin embedded biopsy samples can be analysed without any further preparation, Key publications which illustrate these capacities are presented.