Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

peer reviewedProduction of energy from nuclear power plants generates high-level radioactive nuclear waste, harmful during dozens of thousand years. Deep geological disposal of nuclear waste represents the most reliable solutions for its safe isolation. Confinement of radioactive wastes relies on the multi-barrier concept in which isolation is provided by a series of engineered (canister, backfill) and natural (host rock) barriers. Few underground research laboratories have been built all over the world to test and validate storage solutions. The underground drilling process of disposal drifts may generate cracks, fractures/strain localisation in shear bands within the rock surrounding the gallery especially in argillaceous rocks. These degradations affect the hydro-mechanical properties of the material, such as permeability, e.g. creating a preferential flow path for radionuclide migration. Hydraulic conductivity increase within this zone must remain limited to preserve the natural barrier. In addition galleries are currently reinforced by different types of concrete supports such as shotcrete and/or prefab elements. Their purpose is twofold: avoiding partial collapse of the tunnel during drilling operations and limiting convergence of the surrounding rock. Properties of both concrete and rock mass are time dependent, due to shotcrete hydration and hydromechanical couplings within the host rock. By the use of a hydro-mechanical coupled Finite Element Code with a Second Gradient regularization, this paper aims at investigating and predicting support and rock interactions (convergence, stress field). The effect of shotcrete hydration evolution, spraying time and use of compressible wedges is studied in order to determine their relative influence

Higher education in Indonesia: Contemporary challenges in governance, access, and quality

This chapter presents the development of Indonesian higher education since its origins to current challenges in the fields of governance, autonomy, access, equity, quality, and internationalization. Indonesia has a massive and diversified tertiary education, including experiments in community colleges and online programs. The higher educational system remains mainly centralized, with the exception of some reforms towards financial autonomy. Insufficient public funding hinders the capacity to provide adequate teaching, research, and facilities among other aspects. The consequential rise in student fees contributes to an overrepresentation of students from Java, urban centers, and higher social classes

Numerical Simulations of Void Linkage in Model Materials using a Nonlocal Ductile Damage Approximation

Experiments on the growth and linkage of 10 μm diameter holes laser drilled in high precision patterns into Al-plates were modelled with finite elements. The simulations used geometries identical to those of the experiments and incorporated ductile damage by element removal under the control of a ductile damage indicator based on the micromechanical studies of Rice and Tracey. A regularization of the problem was achieved through an integral-type nonlocal model based on the smoothing of the rate of a damage indicator D over a characteristic length L. The simulation does not predict the experimentally observed damage acceleration either in the case where no damage is included or when only a local damage model is used. However, the full three-dimensional simulations based on the nonlocal damage methodology do predict both the failure path and the failure strain at void linkage for almost all configurations studied. For the cases considered the critical parameter controlling the local deformations at void linkage was found to be the ratio between hole diameter and hole spacing

Perfusion-decellularization of human ear grafts enables ECM-based scaffolds for auricular vascularized composite tissue engineering

Introduction: Human ear reconstruction is recognized as the emblematic enterprise in tissue engineering. Up to now, it has failed to reach human applications requiring appropriate tissue complexity along with an accessible vascular tree. We hereby propose a new method to process human auricles in order to provide a poorly immunogenic, complex and vascularized ear graft scaffold. Methods: 12 human ears with their vascular pedicles were procured. Perfusion-decellularization was applied using a SDS/polar solvent protocol. Cell and antigen removal was examined by histology and DNA was quantified. Preservation of the extracellular matrix (ECM) was assessed by conventional and 3D-histology, proteins and cytokines quantifications. Biocompatibility was assessed by implantation in rats for up to 60 days. Adipose-derived stem cells seeding was conducted on scaffold samples and with human aortic endothelial cells whole graft seeding in a perfusion-bioreactor. Results: Histology confirmed cell and antigen clearance. DNA reduction was 97.3%. ECM structure and composition were preserved. Implanted scaffolds were tolerated in vivo, with acceptable inflammation, remodeling, and anti-donor antibody formation. Seeding experiments demonstrated cell engraftment and viability. Conclusions: Vascularized and complex auricular scaffolds can be obtained from human source to provide a platform for further functional auricular tissue engineered constructs, hence providing an ideal road to the vascularized composite tissue engineering approach

Dissecting the determinants of depressive disorders outcome: an in depth analysis of two clinical cases

Clinicians face everyday the complexity of depression. Available pharmacotherapies and psychotherapies improve patients suffering in a large part of subjects, however up to half of patients do not respond to treatment. Clinicians may forecast to a good extent if a given patient will respond or not, based on a number of data and sensations that emerge from face to face assessment. Conversely, clinical predictors of non response emerging from literature are largely unsatisfactory. Here we try to fill this gap, suggesting a comprehensive assessment of patients that may overcome the limitation of standardized assessments and detecting the factors that plausibly contribute to so marked differences in depressive disorders outcome. For this aim we present and discuss two clinical cases. Mr. A was an industrial manager who came to psychiatric evaluation with a severe depressive episode. His employment was demanding and the depressive episode undermined his capacity to manage it. Based on standardized assessment, Mr. A condition appeared severe and potentially dramatic. Mrs. B was a housewife who came to psychiatric evaluation with a moderate depressive episode. Literature predictors would suggest Mrs. B state as associated with a more favourable outcome. However the clinician impression was not converging with the standardized assessment and in fact the outcome will reverse the prediction based on the initial formal standard evaluation. Although the present report is based on two clinical cases and no generalizability is possible, a more detailed analysis of personality, temperament, defense mechanisms, self esteem, intelligence and social adjustment may allow to formalize the clinical impressions used by clinicians for biologic and pharmacologic studies