FT-IR and NMR structural markers for thiazole-based γ-peptide foldamers.

Nuclear magnetic resonance (NMR) spectroscopy has been established as a potent method for the determination of foldamer structures in solution. However, the NMR techniques could be limited by averaging, so additional experimental techniques are often needed to fully endorse the folding properties of a sequence. We have recently demonstrated that oligo-γ-peptides composed of 4-amino(methyl)-1,3-thiazole-5-carboxylic acids (ATCs) adopt an original helical fold stabilized by hydrogen bonds forming C9 pseudocycles. The main objective of the present work is to reinvestigate the folding of ATC oligomer 1 in order to identify reliable FT-IR and NMR structural markers that are of value for tracking the degree of organization of ATC-based peptides.

Phase diagrams of nanoalloys: influence of size and morphology.

The size dependence of the phase diagram of nanoalloys with a tendency to phase separate is investigated. As the critical temperature may depend on both the size and the morphology of the nanoparticles, we consider nanowires with different cross-sections and also nanotubes with different circumferences. The variation of the critical temperature with the length of all these nanoparticles is systematically studied using Monte Carlo simulations based on an Ising model. A non-monotonic variation of the critical temperature is observed as a function of the length. The maximal value of the critical temperature is reached when the length and the circumference of the nanoparticles are similar. The phase diagrams obtained within two thermodynamic ensembles (the canonical ensemble and the pseudo grand canonical ensemble) are compared and discussed in terms of the behaviour of a single particle or an assembly of nanoparticles in mutual equilibrium with each other.

Ageing of out-of-equilibrium nanoalloys by a kinetic mean-field approach.

This study describes the ageing of bimetallic nanoparticles using a kinetic mean-field method which provides the time evolution of the concentration for each site. We consider the cuboctahedron of 309 atoms in the Cu-Ag system, which is a prototype of systems with a strong tendency to phase separate. Starting from an initial homogenous configuration, we investigate the evolution towards the equilibrium configuration at different temperatures. Surprisingly, at low temperature, the kinetics exhibits a first transition towards an onion-like configuration followed by a second transition towards the equilibrium core-shell configuration. An analysis of the kinetics of the formation and then of the dissolution of the onion-like structure allows us to identify the main paths of the kinetic process.

Very-high-frequency probes for atomic force microscopy with silicon optomechanics.

Atomic force microscopy (AFM) has been consistently supporting nanosciences and nanotechnologies for over 30 years and is used in many fields from condensed matter physics to biology. It enables the measurement of very weak forces at the nanoscale, thus elucidating the interactions at play in fundamental processes. Here, we leverage the combined benefits of micro/nanoelectromechanical systems and cavity optomechanics to fabricate a sensor for dynamic mode AFM at a frequency above 100 MHz. This frequency is two decades above the fastest commercial AFM probes, suggesting an opportunity for measuring forces at timescales unexplored thus far. The fabrication is achieved using very-large-scale integration technologies derived from photonic silicon circuits. The probe's optomechanical ring cavity is coupled to a 1.55 µm laser light and features a 130 MHz mechanical resonance mode with a quality factor of 900 in air. A limit of detection in the displacement of 3 × 10-16 m/√Hz is obtained, enabling the detection of the Brownian motion of the probe and paving the way for force sensing experiments in the dynamic mode with a working vibration amplitude in the picometer range. When inserted in a custom AFM instrument embodiment, this optomechanical sensor demonstrates the capacity to perform force-distance measurements and to maintain a constant interaction strength between the tip and sample, an essential requirement for AFM applications. Experiments indeed show a stable closed-loop operation with a setpoint of 4 nN/nm for an unprecedented subpicometer vibration amplitude, where the tip-sample interaction is mediated by a stretched water meniscus.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, full version]. / Recommandations pratiques pour le diagnostic et la prise en charge de la fibrose pulmonaire idiopathique ­ Actualisation 2021. Version intégrale.

BACKGROUND: Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated. METHODS: Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale. RESULTS: After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis. CONCLUSION: These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

[French practical guidelines for the diagnosis and management of IPF - 2021 update, short version]. / Recommandations pratiques pour le diagnostic et la prise en charge de la fibrose pulmonaire idiopathique ­ Actualisation 2021. Version courte.

BACKGROUND: Since the previous French guidelines were published in 2017, substantial additional knowledge about idiopathic pulmonary fibrosis has accumulated. METHODS: Under the auspices of the French-speaking Learned Society of Pulmonology and at the initiative of the coordinating reference center, practical guidelines for treatment of rare pulmonary diseases have been established. They were elaborated by groups of writers, reviewers and coordinators with the help of the OrphaLung network, as well as pulmonologists with varying practice modalities, radiologists, pathologists, a general practitioner, a head nurse, and a patients' association. The method was developed according to rules entitled "Good clinical practice" in the overall framework of the "Guidelines for clinical practice" of the official French health authority (HAS), taking into account the results of an online vote using a Likert scale. RESULTS: After analysis of the literature, 54 recommendations were formulated, improved, and validated by the working groups. The recommendations covered a wide-ranging aspects of the disease and its treatment: epidemiology, diagnostic modalities, quality criteria and interpretation of chest CT, indication and modalities of lung biopsy, etiologic workup, approach to familial disease entailing indications and modalities of genetic testing, evaluation of possible functional impairments and prognosis, indications for and use of antifibrotic therapy, lung transplantation, symptom management, comorbidities and complications, treatment of chronic respiratory failure, diagnosis and management of acute exacerbations of fibrosis. CONCLUSION: These evidence-based guidelines are aimed at guiding the diagnosis and the management in clinical practice of idiopathic pulmonary fibrosis.

Analysis of Au-Pd driving forces via the effective site energy model: LRO, antisites and enthalpy of permutation.

Recently we have developed a new energetic model based on the determination of the energies on each site of random solid solutions after relaxation as a function of both the local composition and the nominal concentration. It allows to determine the main thermodynamics driving forces of disordered alloys. Here, we extend the effective site energy model to ordered alloys and illustrate the results for the Au c Pd1-c system. As a first step, we show the ability of this energetic model to reproduce the hierarchy of ordered phases. Then, we derive general mean-field analytic formulae for ordered systems and get the phase diagram. We determine the relative role of the cohesive effect, the chemical effect and the size effect and find that the chemical effect differs significantly between the disordered state and the ordered state. Finally, we link the energy formation of antisite to the permutation enthalpy and give the driving forces for the formation of antisite.

Exotic behavior of the outer shell of bimetallic nanoalloys.

In order to build the phase diagram of Cu-Ag nanoalloys, segregation isotherms for the different sites of the outer shell of a 405-atom cluster have been obtained by means of Monte Carlo simulations using N-body interatomic potentials. A dynamical equilibrium in phase space is observed for the (001) facets as well as for the (111) facets of the truncated octahedron. For the (001) facets, the bistability originates from a structural transition, the facets oscillating collectively between a Cu-rich square shape of coordinence 4 and an Ag-rich diamond shape of coordinence 6. For the (111) facets, the bistability is purely chemical and affects each facet individually. We thus predict the possible coexistence of Cu-pure and Ag-pure (111) facets within the same nanoparticle.

Imaging the wave-function amplitudes in cleaved semiconductor quantum boxes

We have investigated the electronic structure of the conduction band states in InAs quantum boxes embedded in GaAs. Using cross-sectional scanning tunneling microscopy and spectroscopy, we report the direct observation of standing wave patterns in the boxes at room temperature. Electronic structure calculation of similar cleaved boxes allows the identification of the standing waves pattern as the probability density of the ground and first excited states. Their spatial distribution in the (001) plane is significantly affected by the strain relaxation due to the cleavage of the boxes.

[Intraspinal rib penetration in four patients in neurofibromatosis vertebral deformities]. / Pénétration intra-canalaire de côtes dans les déformations vertébrales de la neurofibromatose.

We describe the clinical and radiological features observed in four patients with neurofibromatosis-related scoliosis or kyphoscoliosis who developed rib penetration into the intervertebral foraminae. Rib penetration should be searched for on standard and elective x-rays in patients with moderate curvatures. The diagnosis can be confirmed by computed tomography or magnetic resonance imaging of the spine. In case of major deviation, x-rays must be carefully examined, with an accurate search for spinal cord compression to avoid missing the diagnosis. Surgical treatment must consist in ablation of the posterior ends of the dislocated ribs associated with anterior and posterior fusion. It should be performed early to avoid the development of spinal cord compression.

Magnetism: the driving force of order in CoPt, a first-principles study.

CoPt equiatomic alloy orders according to the tetragonal L1(0) structure which favors strong magnetic anisotropy. Conversely, magnetism can influence the chemical ordering. We present here ab initio calculations of the stability of the L1(0) and L1(2) structures of Co-Pt alloys in their paramagnetic and ferromagnetic states. They show that magnetism strongly reinforces the ordering tendencies in this system. A simple tight-binding analysis allows us to account for this behavior in terms of some pertinent parameters.

An interferometric scanning microwave microscope and calibration method for sub-fF microwave measurements.

We report on an adjustable interferometric set-up for Scanning Microwave Microscopy. This interferometer is designed in order to combine simplicity, a relatively flexible choice of the frequency of interference used for measurements as well as the choice of impedances range where the interference occurs. A vectorial calibration method based on a modified 1-port error model is also proposed. Calibrated measurements of capacitors have been obtained around the test frequency of 3.5 GHz down to about 0.1 fF. Comparison with standard vector network analyzer measurements is shown to assess the performance of the proposed system.