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The misfit stress in a thin layer embedded in a semi-infinite matrix has been first determined near the free surface of the structure, using the virtual dislocation formalism. From a Peach-Koehler force analysis, the different equilibrium positions (unstable and stable) of an edge dislocation gliding in a plane of the layer inclined with respect to the upper interface and emerging at the point of intersection of the upper interface and this free surface have been then characterized with respect to the lattice mismatch and the inclination angle of the gliding plane. It has been found that the dislocation may exhibit stable equilibrium position near the interface and/or near the free surface. A diagram of the position stability has been then determined versus the misfit parameter and the inclination angle. The energy variation due to the introduction of an edge dislocation from the free surface until the matrix layer interface has been finally determined, when the dislocation is gliding in the plane inclined with respect to the interface horizontal axis. A critical thickness of the layer beyond which the formation of the dislocation in the interfaces is energetically favorable has been finally determined as well as its position with respect to the free surface in the lower interface. [ABSTRACT FROM AUTHOR]

The equilibrium positions of an edge dislocation embedded in a freestanding thin film submitted to uniaxial stress have been characterized from a Peach–Koehler force calculation. Depending on the inclination angle of the dislocation gliding plane with respect to the film horizontal axis, one stable and two unstable equilibrium positions have been first identified for the dislocation, when the film is stress-free. A critical angle has been also determined beyond which only one unstable equilibrium position remains. The effects of compressive and tensile applied stress have been then analyzed on the dislocation stability in the film and the stress values beyond which no longer the dislocation has a stable equilibrium have been finally determined. [ABSTRACT FROM AUTHOR]

The correction of atmospheric effects on optical remote sensing products is an essential component of Analysis Ready Data (ARD) production lines. The MAJA processor aims at providing accurate time series of surface reflectances over land for satellite missions, such as Sentinel-2, Venμs, and Landsat 8. The Centre d'Études Spatiales de la Biosphère (CESBIO) and the Centre National d'Études Spatiales (CNES) share a common effort to maintain, validate, and improve the MAJA processor, using state-of-the-art ground measurement sites, and participating in processor inter-comparisons, such as the Atmospheric Correction Intercomparison Exercise (ACIX). While contributing to the second ACIX-II Land validation exercise, it was found that the candidate MAJA dataset could not adequately be compared to the main reference dataset. MAJA reflectances were corrected for adjacency and topography effects while the reference dataset was not, excluding MAJA from a part of the performance metrics of the exercise. The first part of the following study aims at providing complementary performance assessment to ACIX-II by reprocessing MAJA surface reflectances without adjacency nor topographic correction, allowing for an un-biased full resolution comparison with the reference Sentinel-2 dataset. The second part of the study consists of validating MAJA against surface reflectance measurements time series of up to five years acquired at three automated stations. Both approaches provide extensive insights on the quality of MAJA Sentinel-2 Level 2 products. [ABSTRACT FROM AUTHOR]

The equilibrium positions of a dipole of edge dislocations embedded in a nanostructure composed of a strained two-dimensional layer buried in an infinite-size matrix with a rectangular nanowire located at the upper layer-matrix interface have been determined from a Peach-Koëhler force calculation. The location of the unstable and stable equilibrium positions of the dislocations of the dipole gliding in the horizontal plane has been specified in the nanostructure versus the misfit strain and nanowire aspect ratio. The critical misfit below which the dipole has no equilibrium position has been finally determined versus the size of the nanowire. [ABSTRACT FROM AUTHOR]

The introduction by climbing of an edge dislocation from the free-surface of a three-layer structure has been first investigated from an energy-based calculation. The activation energy and unstable equilibrium positions of the dislocation have been thus determined versus the misfit parameter. Likewise, the critical strain required for the dislocation introduction in the matrix-layer interface has been characterized. The introduction by climbing of a second dislocation has been then considered. The energy barrier, stable and unstable positions have been again calculated for the second dislocation considering the firstly introduced dislocation is lying in the interface closer to the free-surface. A stability diagram with respect to the introduction of the two dislocations is finally displayed versus the misfit parameter. [ABSTRACT FROM AUTHOR]

The equilibrium positions of two edge dislocations located on either side of a grain boundary have been determined when a disclination dipole is lying in the boundary. It is found that a configuration where the dislocations are distributed symmetrically with respect to the center of symmetry of the grain boundary is selected. This configuration depends on the disclination strength and the dislocation distance from the boundary. [ABSTRACT FROM AUTHOR]

The stability of a dipole of edge dislocations embedded in a cylindrical nanowire of infinite length has been theoretically investigated from a Peach–Koehler (PK) force analysis. Calculating both gliding and climbing components of the PK force, the stable and unstable equilibrium positions of the dislocations have been characterized when the two dislocations, symmetrically displayed with respect to the nanowire center, have the same Burgers vector and when the Burgers vectors are of opposite signs. The size effect of the nanowire on the stability of the dislocations and their relative position to each other are finally discussed and compared to the case where the dislocations are embedded in an infinite-size solid. [ABSTRACT FROM AUTHOR]

The formation of a dipole of edge dislocations inside one grain separated from the adjacent grains by two interfaces in which are lying disclination dipoles (one in each interface) has been theoretically investigated from an energy variation calculation. Critical grain sizes associated with the formation of the edge dislocation dipole have been determined as well as an activation energy. The effects of the inclination angle of the gliding plane of the dislocations and the characteristic parameters of the disclination dipoles have been finally analyzed. [ABSTRACT FROM AUTHOR]

The effect of crystallography and elastic coefficient heterogeneity between a thin film and its substrate has been theoretically investigated on the shear-coupled grain boundary migration in the film. A drag force associated with the elastic energy has been determined by a disclination-based description of the grain boundary migration. Considering also the capillarity driving force derived from the Burke-Turnbull model of normal grain growth, it has been found in case of an Al thin film that the grain growth stagnation occurs beyond a critical film thickness that decreases as the shear modulus and/or Poisson's ratio of the substrate increase from the corresponding values of the film. In case of [ 001 ] grain boundaries in a Cu thin film, the effect of crystallography on the GB displacement has also been characterized. [ABSTRACT FROM AUTHOR]

The buckling of a thin film deposited on an infinitely rigid substrate and delaminated over a finite length is studied in the framework of the Föppl-von Kàrmàn theory of thin plates. Assuming the two edges of the ductile film can fold, an energy-based analysis of the different morphologies of the film has been carried out. Depending on the delamination length, the film can either be unfolded, partially folded at one edge or symmetrically folded at its two edges. [ABSTRACT FROM AUTHOR]

• The stress fields near a free-surface have been determined. • The energy variation due to the loop introduction in the interface has been determined. • The loop equilibrium positions have been determined versus the misfit strain. • The critical radii for the formation of the two dislocations have been determined. The introduction of prismatic dislocation loops in the interface between a misfitting spherical particle and its semi-infinite matrix has been theoretically investigated. The equilibrium position of one isolated loop has been first determined from an energy variation calculation and a shifting effect on the dislocation position relative to the particle equatorial plane has been identified due to the matrix free-surface. The case of two dislocation loops lying in the particle–matrix interface has been then discussed. [ABSTRACT FROM AUTHOR]

The formation of an edge dislocation from the surface of a cylindrical circular cavity lying in a high-angle grain boundary and separating two disclination dipoles located in the boundary has been investigated from a theoretical point of view. The energy variation due to the dislocation introduction into one grain has been determined, and the equilibrium positions (stable or unstable) of the emitted dislocation have been characterized as a function of the direction of the Burgers vector, the strength and length of the disclination dipoles. [ABSTRACT FROM AUTHOR]

The effect of misfit strain on the equilibrium positions of two edge dislocations of the same Burgers vector that are symmetrically displayed in a matrix with respect to its two interfaces with a thin film has been theoretically investigated from a Peach–Koehler force-based analysis. Assuming the film/matrix interfaces are partially coherent, the stable and unstable equilibrium positions of the dislocations have been determined as well as the resulting stability diagram versus the misfit strain, the interface inconsistency length and the layer thickness. • The misfit stress due to partially coherent interfaces is determined. • The Peach–Koehler force on two gliding edge dislocations has been determined. • The equilibrium positions of the dislocations have been determined. [ABSTRACT FROM AUTHOR]

In this paper, we study the wrinkling instability of two layers embedded in a homogeneous matrix of infinite size. Using a linear stability analysis, we characterize the wrinkling of the two layers as a function of the layer spacing and the shear moduli ratio between the two materials. When the layers are stiffer than the surrounding matrix, stiffness contrast largely determines the stability behavior of the system. When the layers are softer than the surrounding matrix, stiffness contrast and layer spacing interact to determine critical threshold strain and wavelength, and result in striking discontinuities in wavelength between regimes. When the layers are close to each other, the system has a strong preference for the symmetric wrinkling mode, but as the distance between the two layers increases, the anti-symmetric mode may emerge. [ABSTRACT FROM AUTHOR]

Highlights • Experimental observations of the interaction between slip traces and vicinal steps on Nb(1 1 1) surface. • Evidence of terrace erosion due to emerging dislocations. • modeling of the step evolution due to adatom diffusion. • suggestion of a mechanism of erosion by step meander formation. Abstract We have investigated the interaction between slip traces and vicinal steps on the Nb(1 1 1) surface under increasing external strain. By exploiting an extended scanning tunneling microscopy analysis, we here show that emerging dislocations at the free-surface can induce the full disappearance of atomic terraces. To shed light on the observed behavior, we have modeled the elastic interaction between a screw dislocation and a vicinal step in the actual experimental configuration. After computing the adatom chemical potential, we show that strain-mediated diffusion on surface causes step erosion, possibly leading to vanishing of full terraces. [ABSTRACT FROM AUTHOR]

Abstract Instabilities of bilayered systems with a thin layer on top of a thick substrate have been extensively studied throughout the past decade; yet, the general instability of a thin layer embedded in a matrix with different stiffnesses above and below the layer remains underinvestigated. Here, we characterize the shape instability of a layer embedded in an inhomogeneous matrix of infinite size using linear stability analysis. The layer and the matrix above and below it are composed of three different incompressible neo-Hookean materials subjected to unidirectional plane strain compression. We characterize the critical strain beyond which wrinkling occurs for varying shear moduli of the three materials. For the special case of a homogeneous matrix, a study of the serpentine and pinched modes of wrinkling reveals that serpentine wrinkling is associated with a selected wavelength if the layer is stiffer than the matrix, whereas no finite wavelength is found in the linear regime for the pinched mode. [ABSTRACT FROM AUTHOR]

The interaction between edge dislocations and a cylindrical circular cavity embedded in an infinite-size solid submitted to a biaxial stress has been studied from a theoretical point of view. In the case where a first dislocation has reached the cavity, a (meta)stable equilibrium position has been found for the second dislocation gliding from infinity in the same plane as the one of the first dislocation. The critical value of the stress for which the second dislocation also reaches the cavity has been determined. An equivalent study has then been performed for the following gliding dislocations. The possibility of formation from the cavity of another dislocation still in the same gliding plane but in the diametrically opposite part of the solid has finally been analyzed. [ABSTRACT FROM AUTHOR]

The sliding phenomenon of a high-angle tilt boundary containing a disclination dipole emerging at the free-surface of a thin film deposited on a semi-infinite substrate is studied theoretically from a static point of view in the framework of a dislocation-based description. The formation from the surface of a dislocation in the boundary is investigated, and its different equilibrium positions are determined in the stress field of the disclination dipole. It is found that the formation of the dislocation in the stress field of the disclination is only possible for an inclined dipole with respect to the normal of the free-surface. Finally, the effects of the inclination angle and strength of the grain boundary disclination dipole on the stable and metastable equilibrium positions of the dislocation are analyzed. [ABSTRACT FROM AUTHOR]

The linear stability analysis of the growth of a cylinder made of a ternary alloy in contact with its melt has been investigated from a theoretical point of view, in presence of stress and interface kinetics. It is found that instability is facilitated as the number of diffusing species increases from two to three. The radii characterizing the different growth regimes of the cylinder and the fluctuation have been determined as a function of the diffusion, elastic and kinetics parameters of the problem. It has been established that unlike interface kinetics that penalizes the growth of the fluctuation, the stress favors its development. In particular, a regime where the growth of the fluctuation is faster than the cylinder one has been identified in the early step of the cylinder development, this regime resulting from a pure elasticity effect. [ABSTRACT FROM AUTHOR]

The introduction of a dislocation from one lateral surface of a two-dimensional buried layer embedded in a matrix has been theoretically investigated in the interfaces between the two materials. It is found that the lower (and longer) interface is a preferential site where the dislocation can be introduced to relieve the misfit strain. For given layer thickness and lattice mismatch between the matrix and the layer phases, a critical angle has been determined beyond which the introduction of the dislocation is energetically favorable. A stability diagram associated with the dislocation formation has been then provided with respect to the misfit strain, inclination angle and layer thickness. The case of a Si x Ge 1 − x layer embedded in a Ge matrix is finally discussed. [ABSTRACT FROM AUTHOR]

The shape stability of a two-dimensional precipitate embedded in a matrix has been theoretically investigated when it is strained due to an anisotropic lattice mismatch between the matrix and the precipitate. In the case of a semi-infinite matrix, the precipitate is found to align perpendicularly to the free-surface direction when both lattice mismatches are equal. When the misfit is anisotropic, the precipitate far from the free-surface always align in the direction of lower misfit in absolute value. When both effects of misfit anisotropy and elastic relaxation due to the free-surface oppose, a critical distance between the precipitate and the free-surface may exist below which the precipitate, initially orientated in parallel with the surface, align along the direction perpendicular to it. The case of a precipitate located near an interface between two elastically inhomogeneous phases is also discussed and the shape modification of the precipitate due to the shear moduli has been characterized. [ABSTRACT FROM AUTHOR]

The parameterization of heat transfer based on remote sensing data, and the Surface Energy Balance System (SEBS) scheme to retrieve turbulent heat fluxes, already proved to be very appropriate for estimating evapotranspiration (ET) over homogeneous land surfaces. However, the use of such a method over heterogeneous landscapes (e.g., semi-arid regions or agricultural land) becomes more difficult, since the principle of similarity theory is compromised by the presence of different heat sources at various heights. This study aims to propose and evaluate some models based on vegetation geometry partly developed by Colin and Faivre, to retrieve the surface aerodynamic roughness length for momentum transfer (z0m), which is a key parameter in the characterization of heat transfer. A new approach proposed by the authors consisted in the use of a Digital Surface Model (DSM) as boundary condition for experiments with a Computational Fluid Dynamics (CFD) model to reproduce 3D wind fields, and to invert them to retrieve a spatialized roughness parameter. Colin and Faivre also applied the geometrical Raupach's approach for the same purpose. These two methods were evaluated against two empirical ones, widely used in Surface Energy Balance Index (SEBI) based algorithms (Moran; Brutsaert), and also against an alternate geometrical model proposed by Menenti and Ritchie. The investigation was carried out in the Yingke oasis (China) using very-high resolution remote sensing data (VNIR, TIR & LIDAR), for a precise description of the land surface, and a fine evaluation of estimated heat fluxes based on in-situ measurements. A set of five numerical experiments was carried out to evaluate each roughness model. It appears that methods used in experiments 2 (based on Brutsaert) and 4 (based on Colin and Faivre) are the most accurate to estimate the aerodynamic roughness length, according to the estimated heat fluxes. However, the formulation used in experiment 2 allows to minimize errors in both latent and sensible heat flux, and to preserve a good partitioning. An additional evaluation of these two methods based on another κB-1 parameterization could be necessary, given that the latter is not always compatible with the CFD-based retrieval method. [ABSTRACT FROM AUTHOR]

The destabilization of the steady-state regime of two semi-infinite half-spaces of different elastic coefficients sliding upon each other has been theoretically investigated when a rate-and-state friction constitutive law controls the sliding. In the framework of linear and isotropic elastodynamics, the effect of the frictional constitutive law has been investigated onto the development of self-excited oscillations as well as the influence of the shear modulus difference between the two materials. The possibility of existence of a stick-slip regime and the conditions for the loss-of-contact are finally discussed. [ABSTRACT FROM AUTHOR]

The diffusion-limited growth of an initially spherical particle of dilute ternary alloy in contact with its melt has been studied from a theoretical point of view and the effects of interface kinetics and multicomponent diffusion have been characterized on the development of a shape perturbation of the sphere. When both concentrations of the diffusing species are imposed in the far-field, the different radii related to the absolute and relative stability of the particle with respect to the development of spherical harmonics have been determined when a linear kinetics law is considered for the solid/liquid interface. The development of the shape fluctuations of the sphere has been also characterized when the flux of both species are set in the far-field. [ABSTRACT FROM AUTHOR]

The stability of an edge dislocation embedded in a two-dimensional structure composed of one layer of ZnS and one layer of Ge has been theoretically investigated from a Peach–Koëhler force-based analysis in the absence of misfit stress and layer bowing effects. The effect of thickness ratio between the two layers of heterogeneous elastic coefficients has been characterized on the different equilibrium positions of the dislocation through the study of the climbing component of the Peach–Koëhler force. It is found that the number (from 3 to 5) and nature (stable or unstable) of these equilibrium positions distributed in both layers vary significantly as a function of the thickness ratio. • Stability of dislocations in a ZnS/Ge bilayer. • Determination of the Peach–Koëhler forces on the edge dislocations. • Study of the stability of the dislocation positions versus the thickness ratio of both layers. • Stable and unstable positions are identified depending on the thickness ratio. [ABSTRACT FROM AUTHOR]

The introduction of a dislocation from the free-surface of a grain A of a polycrystal has been investigated from the theoretical point of view. Assuming two disclination dipoles are lying in a high angle boundary separating the corresponding grain A and a neighbor grain B, the equilibrium position of the dislocation has been determined in the grain A versus the separation distance between the two dipoles, the length and strength of each dipole. [ABSTRACT FROM AUTHOR]

The strain relaxation of an axisymmetrical precipitate embedded in a semi-infinite matrix with a planar free-surface has been theoretically investigated through the generation in the structure of a dislocation dipole. An energy variation calculation has been performed and the formation of the dipole composed of two misfit edge dislocations has been characterised in the interface. It is found that, contrary to the case where the inclusion is embedded in an infinite-size matrix, there exists near the free-surface a preferential plane selected for the dipole formation in the interface which corresponds to the plane perpendicular to the free surface and containing the inclusion centre. A stability diagram of the structure with respect to the dipole formation in the interface has been provided as a function of the misfit strain and the distance of the inclusion from the free-surface, for different values of the inclusion radius. [ABSTRACT FROM AUTHOR]

The formation of two misfit edge dislocations in the interfaces of a stressed thin layer embedded in a matrix has been theoretically investigated from an energy variation calculation as a function of the lattice mismatch between the layer and matrix. The equilibrium positions of the dislocations have been determined and the two configurations where the arm orientations of the dipole are normal or inclined to the interfaces have been discussed versus the nanostructure dimensions and lattice mismatch. [ABSTRACT FROM AUTHOR]

The introduction of a prismatic dislocation loop in the interface of an axisymmetric precipitate embedded in a thin slab of infinite lateral extension has been theoretically investigated. The critical misfit strain resulting from the lattice mismatch between the inclusion and the slab has been characterized for the loop formation versus the thickness of the slab and the radius of the inclusion. The case where the precipitate is embedded in a semi-infinite matrix is also discussed and a stability diagram of the structure is displayed with respect to the loop introduction versus the geometric and misfit parameters. [ABSTRACT FROM AUTHOR]

The formation of a prismatic dislocation loop in the two interfaces of a three-layer nanowire has been theoretical studied from a static energy variation calculation, when the three layers are submitted to misfit strains. Depending on the misfits and different radii of the layers, the possibility of formation of the dislocation loop at the different layer interfaces has been characterized and a stability diagram is provided for the structure. The effect of the external radius of the nanowire is also investigated. [ABSTRACT FROM AUTHOR]

The formation of two misfit edge dislocations is theoretically investigated in the interfaces of a layer embedded in a semi-infinite matrix. Assuming the matrix–layer interfaces are partially coherent, the energy variation resulting from the formation of the dislocations from the lateral free surface of the structure has been determined in the shearing stress field due to the partial misfit. The mechanical stability of the structure is analysed with respect to the dislocation formation as a function of the size of the coherent region of the interface and the misfit strain. [ABSTRACT FROM PUBLISHER]

The linear stability of a single component axi-symmetrical solid in contact with its melt is theoretically investigated with respect to the development of longitudinal sinusoidal fluctuations of wavelengths λ<2πRe, with Re its radius, in the solidification and melting regime. In the solidification regime, the applied stress adds to the temperature gradient to favor the development of the surface fluctuations. In the melting regime where the temperature gradient has a smoothing effect, the applied stress is the main destabilizing source for the cylinder that has been found to undergo morphological instability below a critical radius. [ABSTRACT FROM AUTHOR]

The nucleation of a dipole of edge dislocations is theoretically investigated in a layer embedded in a nanofilm when the nanostructure is submitted to misfit stress. The effect of stress and nanofilm dimensions has been characterized on the introduction of the dipole of misfit dislocations, from the free surfaces to the centre of the layer. A stability diagram for the nanostructure is finally provided with respect to this particular defect nucleation. [ABSTRACT FROM AUTHOR]

The unilateral buckling of a stressed thin film on a substrate has been investigated theoretically in the framework of the Föppl-von Kármán theory of thin plates when an increasing overpressure is considered onto the upper free surface of the film. It is found that, depending on the initial stress in the film and overpressure, two scenarios of evolution may occur. The snap-through of the one-dimensional buckle leading to the full redeposition should take place for low values of the initial stress. When the initial stress exceeds a critical value, a partial redeposition of the buckle should proceed as the overpressure increases. A snap-through while the redeposition mechanism has taken place should also occur for higher values of the overpressure. [ABSTRACT FROM AUTHOR]

The equilibrium positions of two edge dislocations lying in the same gliding plane have been theoretically determined in a structure composed of a thin layer embedded in an infinite-size matrix of different elastic constants, when the two dislocations are symmetrically distributed with respect to the axis of symmetry of the problem parallel to the interfaces. When the Burgers vectors of the two dislocations are equal and the matrix is stiffer than the layer, the equilibrium positions have been found to be unstable in the central layer and stable in the matrix. No equilibrium position is found when the matrix is softer than the layer. When the Burgers vectors are of opposite sign (same norm and direction) and the layer is stiffer than the matrix, the equilibrium positions are stable in the central layer and unstable in the matrix, no equilibrium position being found when the layer is softer than the matrix. [ABSTRACT FROM AUTHOR]

Abstract: The formation of isolated circular islands submitted to misfit strain has been theoretically investigated on the surface of a thin wetting layer of constant thickness deposited on a substrate by calculating the chemical potential of the island atoms. It is found that the island size selected by the misfit strain depends on the difference between the shear moduli of the islands (and wetting layer) and the substrate. An analytical expression for the island radius is derived from the first order development in the shear modulus difference. [Copyright &y& Elsevier]

Abstract: The equilibrium shapes of bilayer islands under anisotropic misfit stress have been theoretically characterized from a thermodynamics point of view. Based on an energy variation calculation, it is found that when the ratio σ between the components of the misfit stress is such that σ =−1, both square and rectangular shaped bilayer islands may coexist depending on the island volume and stress level. When σ ≠−1 and σ <0, the possibility of formation rectangular islands along both perpendicular directions is also discussed. [Copyright &y& Elsevier]

The morphological evolution by surface diffusion of a core-shell spherical particle has been investigated theoretically under hydrostatic pressure when the shear modulii of the core and shell are different. A linear stability analysis has demonstrated that depending on the pressure, shear modulii, and radii of both phases, the free surface of the composite particle may be unstable with respect to a shape perturbation. A stability diagram finally emphasizes that the roughness development is favored in the case of a hard shell with a soft core. [ABSTRACT FROM AUTHOR]

A stress-based criterion for the formation of a periodic distribution of cracks in an infinite-length cylindrical inclusion of radius R embedded in an infinite-size matrix has been established when the inclusion undergoes intrinsic strain. In agreement with previous studies, it is found that the distance separating two consecutive circular cracks of the same radius than that of inclusion does not depend on stress nor elastic coefficients of the material. This critical distance has been found to be of the order of 1.67 R. [ABSTRACT FROM AUTHOR]

Abstract: The morphological evolution of the initially planar solidification and melting fronts of a thin liquid film in a stressed binary alloy has been investigated when diffusion only proceeds in the liquid phase. A linear stability analysis has been performed and the diffusion-controlled evolution of the shape of both fronts has been characterized. The destabilizing effect of stress on the profiles of the interfaces has been identified for a liquid film at rest when the solid is submitted to constant stress and when it is migrating, due to stress gradient, in the hypothesis where concentration field of solute satisfy Laplace’s equation. The possibility of roughness formation in the early beginning of the development of the solid–liquid interfaces has been finally discussed for alloys in the context of a liquid film migration mechanism. [Copyright &y& Elsevier]

Abstract: The morphological stability of the external free surface of a composite structure made of two shells stressed through the interface has been investigated when mass rearrangement along the surface is controlled by surface diffusion. Due to epitaxy or thermal change, an eigenstrain located in the inner shell is considered. The resulting stress and strain tensors have been first calculated assuming that the interface between the two initially spherical shells is coherent. The roughness appearing by surface diffusion on the external surface of the structure has been then developed on a basis of complete spherical harmonics and the linear stability of the surface has been investigated with respect to each harmonic . The growth rate of the lth order harmonic has been determined and the influence of the geometric and physical parameters such as the radius of the interface, the radii of the free surfaces, the intrinsic deformation or the surface energy has been characterized. The case of a spherical solid embedded in a finite-size matrix has been also discussed. [Copyright &y& Elsevier]

The linear stability analysis of the shape of a spherical cavity embedded in an infinitesize matrix under stress has been performed when infinitesimal perturbation from sphericity of the rod is assumed to appear by surface diffusion. Developing the perturbation on a basis of complete spherical harmonics, the growth rate of each harmonic Ylm(θ, φ) has been determined and the conditions for the development of the different fluctuations have been discussed as a function of the applied stress and the order I of the perturbation. [ABSTRACT FROM AUTHOR]

The linear stability of the surface of a transversally isotropic cylinder submitted to uniaxial stress has been theoretically investigated with respect to the development by surface diffusion of longitudinal fluctuations of its radius. The effect of stress has been characterized on the instability threshold. [ABSTRACT FROM AUTHOR]

A peeling mechanism exclusively driven by surface diffusion has been experimentally observed for the oxide layer covering circular buckles appearing on the free surface of implanted silicon samples when internal pressure resulting from implantation is present below the buckles. A theoretical analysis by means of a chemical potential calculation has been also performed and the possibility for the blisters to peel by a new mechanism has been analysed as a function of pressure. [Copyright &y& Elsevier]

• The misfit stress of a precipitate in a semi-infinite matrix has been determined. • The dislocation formation into the precipitate interfaces has been analyzed. • The dislocation positions have been determined versus the geometric parameters. The introduction, from the matrix free-surface, of dislocations in the interfaces of strained precipitates embedded in a semi-infinite matrix has been theoretically investigated. For two consecutive interfaces between the matrix and two neighboring precipitates, the different equilibrium positions of two edge dislocations have been determined versus the misfit strain, the precipitate/precipitate and precipitate/free-surface distances, when each dislocation is gliding in a different interface. The evolution of the critical misfit strain for the dislocation formation in the interfaces has been finally discussed versus the precipitate size. [ABSTRACT FROM AUTHOR]

The buckling of a gold thin film deposited on a rigid substrate has been numerically investigated by means of static molecular dynamics simulations. Three different regimes of deformation have been identified depending on the values of the adhesion energy of the film on its substrate (Γ int). For low adhesion energy, the buckling and gliding through dislocation emission into the interface have been observed. For intermediate values of Γ int , the dissociation of the interfacial dislocations into the film leads to the formation of a Lomer–Cottrell lock that stops the buckle extension, promoting thus the propagation of a crack accompanied by the emission of dislocations. It results in the formation of a twin. For large values of Γ int , the kinking of the interfacial crack has been evidenced along with dislocation nucleation at its tip leading to twins again. Finally, the different evolutions of the film have been summarized in a "behavior" diagram displayed in the plane of applied strain and adhesion energy variables. [ABSTRACT FROM AUTHOR]

We report on molecular dynamics simulations of thin film buckling which show that during the buckling phenomena dislocations can be emitted from specific region of the film where the heterogeneous stress was found to be maximum and larger than in the planar adherent part. A scenario of formation of misfit dislocations in the planar interface which lead to stress relaxation is finally proposed. [ABSTRACT FROM AUTHOR]

The mechanical stability of a strained multilayered nanowire has been investigated qualitatively from an energy variation calculation. Depending on the strain and Dupré energy of the interfaces, it is found that the layers may delaminate. The expression of the critical radius of the coherent zone below which the layers may delaminate has been determined, and a stability diagram is presented for the nanowire. [ABSTRACT FROM AUTHOR]

Purpose: Oocytes containing smooth endoplasmic reticulum aggregates (SERa) have been associated with reduced fertilization and clinical pregnancy rates as well as compromised neonatal outcomes. It was therefore recommended by an Alpha-ESHRE Consensus to discard oocytes presenting this dysmorphism. The data in the literature are nevertheless conflicting and healthy babies have recently been obtained from affected oocytes. The objectives of this study were to compare clinical outcomes between ICSI cycles with and without oocytes affected by smooth endoplasmic reticulum aggregates and to confirm whether affected oocytes can produce healthy babies.Methods: A prospective observational study was performed comparing 714 SERa- ICSI cycles to 112 SERa+ cycles. Among the SERa+ cycles, 518 SERa- oocytes and 213 SERa+ oocytes were analyzed. Fertilization, embryo quality, and pregnancy rates as well as neonatal outcomes were compared between SERa+ and SERa- cycles as well as between SERa+ and SERa- oocytes.Results: The presence of SERa was not associated with an adverse effect on embryological, clinical or neonatal data for SERa+ cycles and oocytes. Seven healthy babies were born from embryos originating from SERa+ oocytes.Conclusions: These results are encouraging and might contribute in the future to a revision of the Alpha-ESHRE Consensus. Larger studies, including a correlation between frequency and size of SERa, clinical outcomes and malformation rates, as well as the follow-up of babies born are nevertheless necessary. In the meantime, the currently conflicting data requires caution when considering transfers of embryos affected by SERa. [ABSTRACT FROM AUTHOR]

On 20 March 2015 a partial solar eclipse occurred at Strasbourg, France, with an obscuration of 72.4%. The consequences of this event were observed under optimal weather conditions with micrometeorological instruments. Among these, the global radiation deficit can be estimated to be of 1.724MJ per horizontal square meter. A modification of the solar spectrum with a greater proportion of photosynthetically active radiation was also observed. The extinction of the solar radiation resulted in a reduction of the net radiation, a sharp decrease in the surface temperatures and a change in all surface heat fluxes. [ABSTRACT FROM AUTHOR]