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The consideration of multiscale characteristics has emerged as a popular component of geospatial data analysis and modeling. However, the practical implementation of such analysis tasks involves time-consuming and computationally intensive processes that require the integration of knowledge and methods from different disciplines (e.g., quantitative geography, signal processing, and natural sciences) and in which large amounts of data have to be processed. Yet, to date, there is few open-source software that enables an efficient and transparent computational workflow. This paper introduces a Python package for the local multiscale analysis of spatial point processes (LomPy). LomPyis specifically designed for processing and analyzing data that is either irregularly spaced or has large data holes over the spatial territory: a common and methodologically challenging property of geoprocessing operations. The first main function of the package computes the multiresolution quantities, while the second applies them to the extraction of fractal and multifractal features at arbitrarily “local” spatial scales. The third function extends the univariate analysis option to multivariate settings. Powerful tools for regression modeling, density estimation, and visualization are also provided. It should be emphasized that the package is efficient on both vector and raster data structures, ensuring a wide range of applicability in urban data science and beyond.

The different stages of an impact on laminated glass are difficult to observe and quantify but are essential for numerical model validation. To assess the performance of this composite to low-velocity (∼10 m/s) high-mass impacts, dynamical impact tests, inspired by ball-drop tests, are performed, equipped with multiple high-speed cameras. From the set of images, a continuous 3D shape reconstruction of the deformed laminated glass over time is performed using Stereo-Digital Image Correlation (S-DIC). Significant brightness and contrast variations captured by two cameras due to large rotations of glass fragments and large strain of the polymer interlayer between fragments render the use of S-DIC difficult as the impactor penetrates deeper into the plate. To circumvent this problem, an axisymmetric regularization is introduced which has the advantage of not requiring prior knowledge of the mechanical behavior for the tested specimen. It is shown that it offers a more extended period of time (as compared to regular S-DIC) over which a trustful analysis can be performed. The time evolution of the fragmented laminated glass and the density of cracks, both available from our analysis, are key ingredients to elaborate quantitative modeling of the dynamic performance of the laminate.

An original methodology using Digital Image Correlation (DIC) has been designed to precisely measure full-field shrinkages of injection molded polymer plates and then to give the opportunity to compare quantitatively extensive numerical simulations to experiments. The principle of the methodology is based on the full-field strain determination between a reference image of the mold and that of injection-molded parts, which are 275 × 100 × 2.2 mm3plates. To allow for DIC calculation, 50 µm-depth engravings were machined by electro-discharge process at the surface of the mold. The result of the analysis is a 2D full-field shrinkage map over the whole plate surface (i.e. flow and transverse), with a standard deviation of 0.03%. The marking density has been shown to have a roughly linear influence on the precision of shrinkage measurement. This methodology allows the quantification of the effect of several injection parameters on in-plane shrinkage fields: holding pressure, injection flow rate and direction, geometry of injection gates, or geometrical constraints. Once the best set of parameters of material constitutive laws is identified for the simulation of polymer plates, the simulation procedure is ready to be applied on more complex 3D geometries.

ABSTRACTWe study the shape of convective rolls in the Marine Atmospheric Boundary Layer from Synthetic Aperture Radar images of the ocean. We propose a multiscale analysis with structure functions which allow an easy generalization to analyse high-order statistics and so to finely describe the shape of the rolls. The two main results are 1) second-order structure function characterizes the wavelength and direction of rolls just like correlation or power spectrum do, 2) high-order statistics can be studied with skewness and flatness which characterize the asymmetry and intermittency of rolls, respectively. This is the first time that the asymmetry and intermittency of rolls are shown from radar images of the ocean surface.

In order to characterize the mechanical behavior of a reinforced concrete beam–column joint, an experiment is designed whereby different histories of increasing cyclic loads are applied, and the structure deformation (as well as the morphology of apparent surface cracks) is studied using multi-view correlation. The complex three-dimensional geometry and the slender nature of the beam and column call for numerous digital cameras were positioned around the specimen. Assessing the feasibility of image acquisition and estimating a priori uncertainties on multi-view correlation became a true challenge. It is shown that the recourse to photo-realistic rendering software provides the needed tools to perform this experiment design optimization.

Multiview correlation is based on the use of explicitly parameterizing surfaces whose deformation is to be measured. In the present analyses, the surfaces are modeled as triangular facets (for local approaches), and with finite-element meshes (for global approaches) using a linear interpolation between nodal displacements. Displacement uncertainty due to the presence of noise in the images is considered. The noise floor levels of the latter are compared for both local and global cases with two different sets of pictures. A priori estimates based on the Hessian of the registration procedure are derived analytically, and a simplified expression is provided that is shown to be in very good agreement with their a posteriori evaluations. The uncertainty difference between local and global approaches is interpreted from their different spatial resolutions.

Physical oncology recognizes tissue stiffness mediated by activation of cancer-associated fibroblasts (CAF) and extracellular matrix remodeling as an active modulator of tumorigenesis, treatment resistance, and clinical outcome. Cholangiocarcinoma (CCA) is a highly aggressive and chemoresistant desmoplastic cancer enriched in CAF. CCA’s stroma mechanical properties are considered responsible for its chemoresistant character. To normalize tumor mechanics, we propose a physical strategy based on remotely light-activated nanohyperthermia to modulate the tumor microenvironment. In this study, we report the use of multifunctional iron oxide nanoflowers decorated with gold nanoparticles (GIONF) as efficient nanoheaters to achieve complete tumor regression following three sessions of mild hyperthermia. The preferential uptake of GIONF by CAF allowed targeting this cell population, which resulted in a significant early reduction of tumor stiffness followed by tumor regression. In conclusion, our study highlights a spatially and temporally controlled physical strategy, GIONF-mediated photothermal therapy to deplete CAF and normalize the tumor mechanics that may apply to desmoplastic cancer and CCA treatment.

Our efforts toward the process development of drug candidate 1are described in a series of two papers. This manuscript focuses on the synthesis of kilogram quantities of acid precursor 2to provide batches of material for preclinical studies and first-in-human clinical trials. Our approach relies on a chiral resolution to furnish the desired stereocenter, a cryogenic carboxylation, and N-alkylation of chloride derivative 26prepared by a Suzuki coupling. Further efforts pursued to improve those key steps that could become issues on larger scale are also discussed.

This paper describes the synthesis of kilogram quantities of the sulfonamide moiety 3involved in a coupling reaction with acid moiety 2to provide batches of drug candidate 1for preclinical studies and first-in-human clinical trials. A first approach relying on a chiral separation furnished the desired enantiomer of 1,3-diamine 20, precursor of sulfonamide 3. An enantiomeric synthesis of 20using the Ellman’s chiral auxiliary coupled with an aza-Reformatsky reaction to control the stereochemistry is also discussed. Coupling conditions of the final step involving EDCI to provide 1under a cGMP process are detailed. An alternative approach using N-(1-methanesulfonyl)benzotriazole is also presented.

We consider a dynamic approach to games in extensive forms. By restricting the convertibility relation over strategy profiles, we obtain a semi-potential (in the sense of Kukushkin), and we show that in finite sequential games the corresponding restriction of better-response dynamics will converge to a Nash equilibrium in quadratic time. Convergence happens on a per-player basis, and even in the presence of players with cyclic preferences, the players with acyclic preferences will stabilize. Thus, we obtain a candidate notion for rationality in the presence of irrational agents. Moreover, the restriction of convertibility can be justified by a conservative updating of beliefs about the other players strategies. For infinite games in extensive form we can retain convergence to a Nash equilibrium (in some sense), if the preferences are given by continuous payoff functions; or obtain a transfinite convergence if the outcome sets of the game are Δ20-sets.

This paper presents the characterization and management of dynamic thermocline behaviors in a single-medium thermocline (SMT) thermal energy storage tank with the aim of its performance improvement. In particular, the flow mixing induced by the entering thermal jet, its impact on the temperature stratification and its mitigation measure are systematically explored by both numerical and experimental methods. Results of CFD simulation and Particle Image Velocimetry (PIV) visualization clearly demonstrate the jet entrainment phenomenon and the typical flow patterns featured by the rising buoyant plumes. For the storage tank with simple inlet port, this thermal jet would cause the thermal overturning, the strong fluid mixing and convection heat transfer, resulting in the degradation of temperature stratification and the thermocline decay (Rigradient<0.25at certain positions of the tank). It has also been shown by PIV measurement that the impact of thermal jet, characterized by the jet penetration length, becomes stronger with the increasing injecting flow rate and with the decreasing temperature difference between the injecting and existing fluids.

The present study aims at demonstrating the feasibility of performing a fracture test in less than 1 min in a laboratory CT scanner despite the severe time constraints of tomography acquisition. After introducing the basic concepts of projection-based digital volume correlation, the specific implementation of this methodology to a wedge splitting test on a refractory material is presented. The kinematics of the test is described over a mesh tailored to the sample geometry, and the elastic behavior of the sample is exploited through finite element computations to provide sensitivity fields of experimental boundary conditions to allow for their “measurements.” Enhancing the simulation to account for crack advance with extended finite element analyses allows the sensitivity of the procedure to the crack position to be assessed. A confidence interval for the refractory toughness is finally obtained.

A projection-based digital volume correlation method (presented in a companion paper) is extended to an integrated approach for the calibration of an elastoplastic law based on a single radiograph per loading step. Instead of following a two-step sequential procedure (i.e. first, measurement of the displacement field; second, identification), the integrated method aims at identifying few model parameters directly from the gray-level projections. The analysis of an in situ tensile test composed of 127 loading steps performed in 6 min is presented. An isotropic elastoplastic constitutive law with free-form hardening behavior (i.e. controlled by only eight parameters) is identified and shows a ductile behavior (up to 6.3% strain before failure). A large improvement on the residual quality is shown and validates the proposed model and procedure. The obtained displacement fields are similar to those measured with no mechanical integration. A different parameterization of the constitutive law provides a very close result, thereby assessing the robustness of the procedure.

The measurement of four-dimensional (i.e. three-dimensional space and time) displacement fields of in situ tests within X-ray computed tomography scanners (i.e. lab-scale X-ray computed tomography) is considered herein using projection-based digital volume correlation. With a singleprojection per loading (i.e. time) step, the developed method allows the loading not to be interrupted and to vary continuously during the scan rotation. As a result, huge gains in acquisition time (i.e. more than two orders of magnitude) need to be reached. The kinematic analysis is carried out using predefined space and time bases combined with model reduction techniques (i.e. proper generalized decomposition with space–time decomposition). The accuracy of the measured kinematic basis is assessed via gray-level residual fields. An application to an in situ tensile test composed of 127 time steps is performed. Because of the slender geometry of the sample, a specific beam space regularization is used, which is composed of a stack of rigid sections. Large improvements on the residual, the signal-to-noise ratio of which evolves from 9.9 to 26.7 dB, validate the procedure.

The interactions between plasticity and damage mechanisms are not clearly established concerning the fracture of ductile sheet materials (e.g., flat to slant transition). The question addressed herein is to elucidate which mechanism is responsible for localized phenomena leading to the final failure. A mechanical test carried out on a notched plate made of 2139-T3 aluminum alloy is imaged thanks to synchrotron laminography at micrometer resolution. Ductile damage (i.e., void nucleation, growth and coalescence) is analyzed via reconstructed volumes. Although the low volume fraction of secondary phases in the tested alloy is challenging, digital volume correlation is also utilized to measure displacement fields and estimate strain fields in the bulk of the alloy during the whole test. In the first part of this study, the resolution of the measurement technique is assessed under such conditions. Then strained bands are shown to occur very early on in what will be the slant region of the fracture path. Conversely, damage grows at very late loading steps.

The identification of the parameters of several constitutive laws is performed with the integrated digital image correlation (IDIC) technique in a biaxial experiment for a cruciform specimen made of stainless steel. The sought material parameters are assessed with the contribution of both reaction forces (from load sensors) and displacement fields (measured via digital image correlation). For each constitutive law a global residual quantifying the model error is assessed.

Thermal shocks are applied to a 304L austenitic stainless steel plate with a pulsed laser. A stroboscopic reconstruction is used for infrared (IR) and visible light camera measurements. The displacement fields are measured with a digital image correlation (DIC) technique. Different IR devices are used to measure the temperature variations (i.e.medium wave camera and short wave pyrometry). Several ways of determining the emissivity or absorptivity are discussed. The complete 3D thermal loading is numerically determined by minimising the difference between experimental measurements and finite element analyses of thermal fields. An elastoplastic model is then used to compute mechanical fields that are compared with DIC measurements.

Fracture propagation involves the coupling of many length scales ranging from the sample loading geometry to the molecular level. In brittle materials, the length scales of the damage process zone are reduced to a submicrometric scale and the coupling with the macroscopic scale is expected to be the domain of linear elastic fracture mechanics. However, although 2D elastic analyses are generally adequate to describe the sample deformation at macroscopic scales, local investigations of failure mechanisms at the sample-free surface require the use of 3D mechanical tools due to the crack front local curvature and to the corner point singularities at the intersection between the crack front and the external surfaces of the sample. We present here a thorough multiscale investigation of the slow crack growth of a sharp crack in oxide glasses in the stress-corrosion regime, combining experimental and numerical analyses of the displacement fields from the millimeter scale to the nanoscale range. The principal aim of the study is identifying the length and time scales of the mechanisms of damage and interaction between water and glass, which have been the subject of an extensive debate in the last decades.

It is proposed to develop a multiview framework to perform stereocorrelation by resorting to isogeometric descriptions of the observed three-dimensional surfaces. Once the three-dimensional surfaces have been reconstructed, the corresponding three-dimensional displacement fields are measured within the same space. These fields are subsequently utilized to update isogeometric analyses to calibrate the elastic properties in a tensile experiment. An alternative route consists of preforming such analyses within an integrated framework.

AGuIX nanoparticles are formed of a polysiloxane network surrounded by gadolinium chelates. They present several characteristics. They are easy to produce, they present very small hydrodynamic diameters (<5 nm) and they are biodegradable through hydrolysis of siloxane bonds. Such degradation was evaluated in diluted conditions at physiological pH by dynamic light scattering and relaxometry. AGuIX nanoparticles are also known as positive contrast agents and efficient radiosensitizers. The aim of this paper is to compare their efficiency for magnetic resonance imaging and radiosensitization to those of the commercial gadolinium based molecular agent: DOTAREM®. An experiment with healthy animals was conducted and the MRI pictures we obtained show a better contrast with the AguIX compared to the DOTAREM® for the same amount of injected gadolinium in the animal. The better contrast obtained after injection of Aguix than DOTAREM® is due to a higher longitudinal relaxivity and a residential time in the blood circulation that is two times higher. A fast and large increase in the contrast is also observed by MRI after an intravenous injection of the AGuIX in 9 L gliosarcoma bearing rats, and a plateau is reached seven minutes after the injection. We established a radiotherapy protocol consisting of an irradiation by microbeam radiation therapy 20 minutes after the injection of a specific quantity of gadolinium. After microbeam radiation therapy, no notable difference in median survival time was observed in the presence or absence of gadolinium chelates (38 and 44 days respectively). In comparison, the median survival time is increased to 102.5 days with AGuIX particles showing their interest in this nanomedicine protocol. This remarkable radiosensitizing effect could be explained by the persistent tumor uptake of the particles, inducing a significant nanoscale dose deposition under irradiation.

We investigate the velocity dependence of the friction between two rigid blocks limited by a self-affine surface such as the one generated by a crack. The upper solid is subjected either to gravity or to an external elastic stiffness, and is driven horizontally at constant velocity, V, while the lower solid is fixed. For low velocities, the apparent friction coefficient is constant. For high velocities, the apparent friction is shown to display a velocity weakening. The weakening can be related to the variation of the mean contact time due to the occurrence of jumps during the motions. The cross-over between these two regimes corresponds to a characteristic velocity which depends on the geometry of the surfaces and on the mean normal force. In the case of simple gravity loading, the velocity dependence of the apparent friction at high velocities is proportional to 1/V2where V is the imposed tangential velocity. In the case of external elastic stiffness, two velocity weakening regimes can be identified, the first is identical to the gravity case with a 1/V2dependence, the second appears at higher velocities and is characterized by a 1/V variation. The characteristic velocity of this second cross-over depends on the roughness and the elastic stiffness. The statistical distribution of ballistic flight distances is analysed, and is shown to reveal in all cases the self-affinity of the contacting surfaces.

We study an ensemble of polymers that strongly interact with the surrounding medium. One end of the polymers is fixed, but otherwise there are no restrictions on their possible conformations, allowing also self-crossings. We study in this paper by a Flory argument and by numerical methods the statistical properties of these in the low-temperature limit. We find that these properties strongly depend on the disorder of the surrounding medium, in contrast to the directed polymercase.

We study a simple model for thé pinning of an interface by impurities with random strengths, and thé depinning due to thé applied pressure, in a quasi-static propagation lirait. The model is very close to thé so called "Robin Hood" model introduced by Zaitsev. It is designed to describe e.g. thé invasion of a wetting fluid (imbibition) in a heterogeneous porous medium containing a second immiscible fluid. The relation between this model and other previously proposed approaches is discussed. The front of thé invaded domain is shown to develop a self-affine structure with an increase of thé roughness as a power-law of thé injected volume. The value of thé apparent roughness exponent can be favorably compared to some experimental measurements although we argue that thé true roughness exponent is out of reach of commonly used methods. We show that thé distribution f(d, Δt) of distances d between discrete local invasions at a time interval Δt can be described by a scaling law $f(d, \Delta t) = d^{-1}\varphi(d/\sqrt{\Delta t})$. This form can be obtained from thé identification of a hierarchical structure of "bursts" in thé pressure signal. Those "bursts" are quahtatively similar to those observed in quasistatic drainage, (i.e. invasion percolation), although characterized by différent scaling indices.

We study an extremal Hamiltonian for directed polymers. The ground states are degenerate and they form a cluster of directed percolation. This degeneracy has a hierarchical fractal structure and can be lifted by a progressive optimization.

We introduce a simple cellular automaton to model the force distribution in a gravity-loaded granular medium. Two test cases are considered: the sand heap, and the silo geometry. The model gives results consistent with established observations. For the heap, the normal stress on the base plane displays a pronounced depression underneath the apex. In the silo geometry, the model reproduces the correct scaling for the approach to a stationary (depth-independent) stress state.

We consider a composite medium which consists in resistance elements with a distibution of conductance, in a narrow range around a mean value. The question we address is the distibution of local power dissipation, and its correlation with the local conductance. Various discretizations of the problem are considered: regular networks of different types in two and three dimensions whose bonds are assigned conductances at random, finite element method with random distibution of conductances in each element. We also consider the case of elastic elements, and study the distibution of elastic energy stored in each element. It is shown that the correlation between the dissipated (or elastic) energy and the conductance (or elastic modulus) depends on the discretization. These correlations are analysed in an effective medium theory framework, and numerical simulations confirm the theoretical predictions. The distribution of local energy always tends towards a Gaussian distibution for all cases considered, in the limit of a small disorder.

We study numerically a simple network model which is an electrical analog of a perfectly plastic disordered medium. For a uniform random distribution of local maximum current, (e.g. yield stress), we study the evolution of the properties of the system as a function of the number of elements which reached the plastic limit. It is shown that the macroscopic yield point can be interpreted as a critical point.

Full-Field OCT (FF-OCT) is able to image biological tissues in 3D with micrometer resolution. In this study we add elastographic contrast to the FF-OCT modality. By combining FF-OCT with elastography, we create a virtual palpation map at the micrometer scale. We present here a proof of concept on multi-layer phantoms and preliminary results on ex vivo biological samples such as porcine cornea, human breast tissues and rat heart. The 3D digital volume correlation that is used in connection with the 3D stack of images allows to access to the full 3D strain tensor and to reveal stiffness anisotropy.

Functional colloidal nanoparticles capable of converting between various energy types are finding an increasing number of applications. One of the relevant examples concerns light-to-heat-converting colloidal nanoparticles that may be useful for localized photothermal therapy of cancers. Unfortunately, quantitative comparison and ranking of nanoheaters are not straightforward as materials of different compositions and structures have different photophysical and chemical properties and may interact differently with the biological environment. In terms of photophysical properties, the most relevant information to rank these nanoheaters is the light-to-heat conversion efficiency, which, along with information on the absorption capacity of the material, can be used to directly compare materials. In this work, we evaluate the light-to-heat conversion properties of 17 different nanoheaters belonging to different groups (plasmonic, semiconductor, lanthanide-doped nanocrystals, carbon nanocrystals, and metal oxides). We conclude that the light-to-heat conversion efficiency alone is not meaningful enough as many materials have similar conversion efficiencies─in the range of 80–99%─while they significantly differ in their extinction coefficient. We therefore constructed their qualitative ranking based on the external conversion efficiency, which takes into account the conventionally defined light-to-heat conversion efficiency and its absorption capacity. This ranking demonstrated the differences between the samples more meaningfully. Among the studied systems, the top-ranking materials were black porous silicon and CuS nanocrystals. These results allow us to select the most favorable materials for photo-based theranostics and set a new standard in the characterization of nanoheaters.

Even though the past three decades have seen numerous crucial investigations on interurban scaling characteristics, there has been less focus on revealing multiscale properties within municipal or metropolitan structures. We demonstrate how a newly developed methodology, the Geographically Weighted Multiscale Analysis (GWMSA) stemming from the theory of multifractal systems, can be used to analyze small-scale urban environments with respect to their intermittency and roughness simultaneously. To this end, apart from the widely used sand-box method, we introduce wavelet coefficients in the multiscale analysis of urban systems. In more detail, the spatially continuous scanning of the three largest French conurbations—Paris, Marseille, and Lyon—over their territories and at length scales ranging from parcel to neighborhood level will allow to derive and compare globally and locally characteristic scaling exponents. Depending on the feature under analysis, the exponents reveal qualitatively distinct structural properties, whereby the viability of our findings is further verified on four exemplary typologies of multiscale behavior in urban systems. To introduce GWMSA, this paper focuses primarily on morphological characteristics and findings provide a compelling alternative to how we capture and define district-scale spatial organization and interdependencies within urban settlements.

By construction, digital image correlation is an ill-posed problem. To circumvent this difficulty, regularization is often performed implicitly through the kinematic basis chosen to express the sought displacement fields. Conversely, a priori information on the mechanical behavior of the studied material is often available. It is proposed to evaluate the gain to be expected from such a mechanical assistance, namely, the measured displacement not only satisfies as best as possible the gray-level conservation but also mechanical admissibility.

Magnetic nanoparticles exhibit a high potential to selectively treat cancer by hyperthermia provided that high heating capacity can be reached. In this work, we report an efficient synthesis of novel structures of magnetic iron oxide. The particles, obtained by applying a modified “polyol” protocol, present a particular shape: they look constituted of smaller grains of approximately 11 nm, assembled in a flower-shaped structure. These nanoflowers, dispersed in water at physiological pH, present particularly interesting magnetic properties and a great capacity of heating. The value of the specific loss power (SLP) of these nanoflowers is 1 order of magnitude higher than the SLP reported for conventional 11 nm single-domain maghemite nanoparticles in the same condition of field exposure.

Most often, digital image correlation is used to analyse a sequence of images. Exploitation of an expected temporal regularity in the displacement fields can be used to enhance the performances of a digital image correlation analysis, either in terms of spatial resolution, or in terms of uncertainty. A general theoretical framework is presented, tested on artificial and experimental image series.

Ultrasmall gadolinium-based nanoparticles (GBNs) induce both a positive contrast for magnetic resonance imaging and a radiosentizing effect. The exploitation of these characteristics leads to a greater increase in lifespan of rats bearing brain tumors since the radiosensitizing effect of GBNs can be activated by X-ray microbeams when the gadolinium content is, at the same time, sufficiently high in the tumor and low in the surrounding healthy tissue. GBNs exhibit therefore an interesting potential for image-guided radiotherapy.

Ultrasmall but multifunctional: Rigid imaging particles that are smaller than 5 nm in size can be obtained in a top‐down process starting from a core–shell structure (core=gadolinium oxide; shell=polysiloxane). They represent the first multifunctional silica‐based particles that are sufficiently small to escape hepatic clearance and enable animal imaging by four complementary techniques.

Global digital volume correlation is used to analyze a series of computed tomography images of a nodular graphite cast iron specimen subjected in situ to a fatigue test. From the obtained displacement field, a specific procedure is implemented to extract stress intensity factors all along the crack front. The proposed methodology allows one to measure key parameters in fatigue crack propagation directly from 3D images.

Owing to their multifunctional character, nanoparticles appear well suited for combining sensing, imaging and therapy. Nanoparticles composed of a gadolinium oxide core and a polysiloxane shell were designed for the detection of biomolecules, fluorescence and MRI, and for cancer therapy. Each component (gadolinium oxide core and polysiloxane shell) of these nanoparticles plays a crucial role and enables the resulting nanoparticles to emit intense but transient light and/or long-lived and highly photostable light, to enhance the contrast of magnetic resonance images, to improve the colloidal stability, to specifically interact with biomolecules, to absorb x-ray photons and to capture thermal neutrons. The hybrid gadolinium oxide nanoparticles exhibit a great potential for sensing applications and for image-guided therapy.

To reduce the measurement uncertainty, a measurement technique is proposed for estimating full displacement fields by complementing digital image correlation with an additional penalization on the distance between the estimated displacement field and its projection onto the space of elastic solutions. The extended finite element method is used for inserting discontinuities independently of the underlying mesh. An application to the brittle fracture of a silicon carbide specimen is used to illustrate the application. To complete the analysis, the crack tip location and the stress intensity factors are estimated. This allows for a characterization of the measurement and identification procedure in terms of uncertainty.

For labeling proteins (streptavidin and fibronectin) by luminescent aminated nanoparticles, an interesting strategy that requires neither activation nor chemical pre- or post-treatment was explored. Because biomolecules are easily rendered luminescent after reaction with organic dyes carrying isothiocyanate moiety, phenylene diisothiocyanate (DITC) was used for covalently binding proteins onto luminescent hybrid gadolinium oxide nanoparticles whose ability to combine imaging and therapy was recently demonstrated.

Abstract: The synthesis of gold nanoparticles functionalized by gadolinium chelates constitutes an attractive way for combining imaging and therapy. The presence of gadolinium chelates allows monitoring their biodistribution after intravenous injection in small animals by magnetic resonance imaging (MRI) while the gold core strongly absorbs the X-ray photons. This feature is exploited for X-ray imaging but also for radiotherapy.

Abstract: In this paper, we present a review of our activities in the field of gold biosensors. Nanostructured gold surfaces can be used in biology for their plasmonic and/or catalytic properties. In a first part, we show how the gold plasmonic properties allow the detection of the biotin-streptavidin binding by two types of techniques: extinction spectroscopy and also luminescence spectroscopy when the probe (here the streptavidin) is labelled by polysiloxane particles encapsulating fluorophores. In a second part, we demonstrate that the catalytical properties of gold corrugated surfaces can significantly enhance the chemiluminescence of luminol brought at vicinity. We found that the surface-enhancement induced by gold is two times of magnitude greater than that induced by silver.

Une approche multi-échelles de la corrélation d'images numériques est présentée. Elle permet de résoudre précisément les fluctuations du champ de déplacement. Cette technique de mesure est ensuite appliquée à des essais de compression et d'arrachement réalisés sur laine de verre crêpée. Les champs de déplacement et de déformation sont alors déterminés. Cette méthode révèle, lors de la réalisation d'essais de compression, des hétérogénéités de déformation, prémices de la localisation, bien avant le plateau de contrainte. Les essais d'arrachement permettent d'identifier l'amorçage et la propagation de fissures. La fiabilité et la résolution des champs de déplacements et de déformations sont validées en utilisant différents paramètres lors de l'analyse par corrélation.

Lors de leur cycle de fabrication, des contraintes résiduelles sont générées notamment dans la partie fragile d'assemblages céramique/métal. Ces dernières sont responsables de l'amorçage et de l'arrêt des fissures générées par ce cycle, mettant en défaut les traitements probabilistes de la rupture basés sur l'hypothèse du maillon le plus faible. Un modèle probabiliste de fissuration est proposé et permet d'appréhender de tels arrêts. Une extension de ce modèle considère la fiabilité des assemblages soumis à de la fatigue statique. Une méthodologie d'identification des paramètres aléatoires microstructuraux est proposée. La démarche est ensuite appliquée à la prévision de la durée de vie d'un composant industriel.

We propose a multiscale approach to determine the displacement field by digital image correlation. The displacement field is first estimated on a coarse resolution image and progressively finer details are introduced in the analysis as the displacement is more and more securely and accurately determined. Such a scheme has been developed to increase the robustness, accuracy, and reliability of the image-matching algorithm. The procedure is used on two different types of examples. The first one deals with a representative image that is deformed precisely and purposefully to assess the intrinsic performances. In particular, the maximum measurable strain is determined. The second case deals with a series of pictures taken during compression experiments on mineral-wool samples. The different steps of the procedure are analyzed and their respective role is assessed. Both reflection and transmission images are tested.

We describe the preparation of new hybrid materials using a novel method previously reported by us. These materials are constituted of an organic part and an inorganic network of silicon and zirconium oxopolymers. The organic polymer is obtained by electropolymerization of an N-functionalized pyrrole entrapped in the xerogel. The latter was obtained from a sol prepared by hydrolysis condensation of a mixture of alkoxysilanes, zirconium alkoxydes and the organic monomer. The chemical and electrochemical conditions to prepare these hybrid materials were investigated by varying the zirconium content, the presence and the nature of doping species in the xerogel, the nature of the electrolytic salt and the hydrolysis catalyst. From the results of cyclic voltammetry, optical microscopy, scanning electron microscopy and X-ray fluorescence, we show that the formation of a conducting polymer with good properties in the xerogel depends on the zirconium content and on both the nature and the presence of doping species in the xerogel, whereas the influence of the electrolytic salt is very limited.