A Virtual Testing Approach for Laminated Composites Based on Micromechanics

International audienceThe chapter deals with a crucial question for the design of composite structures: how can one predict the evolution of damage up to and including final fracture? Virtual testing, whose goal is to drastically reduce the huge number of industrial tests involved in current characterization procedures, constitutes one of today’s main industrial challenges. In this work, one revisits our multiscale modeling answer through its practical aspects. Some complements regarding identification, kinking, and crack initiation are also given. Finally, the current capabilities and limits of this approach are discussed, as well as the computational challenges that are inherent to “Virtual Structural Testing.

Haematopoietic stem cell transplantation for severe autoimmune diseases in children : a review of current literature, registry activity and future directions on behalf of the autoimmune diseases and paediatric diseases working parties of the European Society for Blood and Marrow Transplantation

Although modern clinical management strategies have improved the outcome of paediatric patients with severe autoimmune and inflammatory diseases over recent decades, a proportion will experience ongoing or recurrent/relapsing disease activity despite multiple therapies often leading to irreversible organ damage, and compromised quality of life, growth/development and long-term survival. Autologous and allogeneic haematopoietic stem cell transplantation (HSCT) have been used successfully to induce disease control and often apparent cure of severe treatment-refractory autoimmune diseases (ADs) in children. However, transplant-related outcomes are disease-dependent and long-term outcome data are limited in respect to efficacy and safety. Moreover, balancing risks of HSCT against AD prognosis with continually evolving non-transplant options is challenging. This review appraises published literature on HSCT strategies and outcomes in individual paediatric ADs. We also provide a summary of the European Society for Blood and Marrow Transplantation (EBMT) Registry, where 343 HSCT procedures (176 autologous and 167 allogeneic) have been reported in 326 children (<18 years) for a range of AD indications. HSCT is a promising treatment modality, with potential long-term disease control or cure, but therapy-related morbidity and mortality need to be reduced. Further research is warranted to establish the position of HSCT in paediatric ADs via registries and prospective clinical studies to support evidence-based interspeciality guidelines and recommendations

Combined use of FBG sensors and SMA actuators for concrete beams repair

The combined use of sensing and actuating systems enables the development of intelligent structures, which can respond in a predetermined manner to changes in the environment or in the structural conditions. In this work, small-scale smart reinforced concrete beams with fibre Bragg grating (FBG) sensors and shape memory alloy (SMA) actuators are designed and tested. SMA wires placed within sleeves are added to the traditional steel reinforcement. The recovery stress developed in the SMA on heating provides the smart beam with a temporary restoring force, which decreases the residual midspan displacement and crack width. As the recovery stress relaxes on cooling of the SMA wires, the proposed method is effective to provide a temporary beam repair, while a long-term strengthening could be achieved by combining the SMA effect of crack closure with other techniques, such as carbon fibre reinforced polymer (CFRP) plating or resin injection. FBG sensors are used to monitor the deformation in the SMA wires and to determine the beam critical conditions. The effectiveness of both the sensing and the actuating methods is experimentally demonstrated, while the different factors influencing the amount of repair provided by the SMA actuators still need to be investigated

Temporary repair of concrete beams by embedded shape memory alloy actuators

The development of smart materials has paved the way to the creation of adaptive and self-healing structures. Shape memory alloys (SMA) embedded in a structure can provide crack closure and temporarily restore structural integrity. The active emergency repair should be followed by long term strengthening, which benefits from the reduced crack width. Here, small scale self-healing concrete beams are built and tested. Prestrained SMA wires are embedded in the beam, while fibre Bragg grating (FBG) sensors are used to detect a critical beam conditions and activate the emergency repair. The actuation of the shape memory alloy elements leads to a crack size reduction and to a decrease in the inelastic beam displacement. Further experimental investigation is necessary to determine the influence of beam ductility and other factors on the amount of repair provided by the SMA actuators

Effect of the Loading History on Shape Memory Alloy Transformation Temperatures

Due to the complex microstructure and phase transformations taking place in Shape Memory Alloys (SMA), the behaviour and properties of these materials are deeply influenced by their loading history in terms of stress, strain and temperature. Indeed, a thorough understanding of the effects of the loading history on SMA properties is fundamental for a correct modelling and design of SMA applications, in particular in the case of complex loading. An example are shape memory alloys embedded in composite systems, in which stress, strain and temperature vary simultaneously depending upon the properties of the SMA and composite. This work presents the first results of an experimental investigation on the effects of the loading history on SMA transformation temperatures. Nitinol wires of untrained material were considered. Specimens consisting of Martensite and R-phase were subjected to different loading histories, keeping in turn stress, strain or temperature at a constant value. Transformation temperatures at zero stress of these samples were measured via Differential Scanning Calorimetry. Contrarily to most constitutive models assumptions, the DSC results highlight a dependence of the transformation temperatures on the loading history, influencing in particular the Martensite to Austenite phase transformation

Modern treatment in chronic lymphocytic leukemia: impact on survival and efficacy in high-risk subgroups.

Treatment of chronic lymphocytic leukemia (CLL) has dramatically changed over the last years, with significant improvement in overall survival (OS) and increased efficacy in genetically defined "high-risk" disease. Besides prospective clinical trials usually enrolling young and fit patients, retrospective studies were performed comparing the outcome of patients belonging to different age groups and showing longer survival in patients diagnosed in the most recent periods. In patients younger than 70 years the 10-year relative survival was 43-53% in the 1980s as compared with 59-63% in the 2000s. Likewise, the 10-year relative survival in patients >70 years was 22-42% in the 1980s and 46-55% in the 2000s. Improved outcome derived in part by the introduction of effective regimens in genetically defined "high-risk" disease (i.e., 17p-, 11q-, TP53, NOTCH1, SF3B1 mutations), especially in the younger and/or fit patients. The unfavorable prognostic significance of 11q- was overcome by chemoimmunotherapy. High-dose steroids with anti-CD52 appeared to improve the response rate in 17p-/TP53 mutated cases and allogeneic transplantation achieved prolonged disease control irrespective of high-risk disease. Further improvement is being generated by the new anti-CD20 obinutuzumab in the elderly and by mechanism-based treatment using kinase-targeting agents or anti-BCL2 molecules yielding high-response rate and impressive progression-free survival in the chemorefractory setting as well as in previously untreated patients

A multi-scale approach for the analysis of the mechanical effects of salt crystallisation in porous media

International audienceIn this paper, a multi-scale approach for the analysis of mechanical effects induced by salt crystallisation in porous media is presented. The approach is based on numerical homogenisation and allows to predict the effects of salt crystallisation occurring at the scale of the structure, based on the real 3D micro geometry of the porous material coming from X-ray Micro Computed Tomography images. The micro-mechanical model is obtained by automatically converting the images into a finite element mesh. The macro-scale distribution of the crystallized salt is assumed as an input datum coming from Hygro Thermal Chemical models available in the literature. Then, some hypotheses on the loading condition of the micro-mechanical model, accounting for different crystallisation physics, are introduced and their effects in terms of mechanical response at the macro-scale are compared. As case study, the proposed approach is applied to the Prague sandstone. Results show that the macro-scale mechanical effects are influenced by the loading scheme and that some approaches commonly used in the literature for their evaluation can lead to their underestimation. The proposed approach can be incorporated in a structural computation with environmental-mechanical loadings to forecast the most probable damage scenarios

Complete remission of Sweet's syndrome after azacytidine treatment for concomitant myelodysplastic syndrome

Sweet's syndrome is a rare condition with potentially disabling implications, characterized by painful skin lesions due to neutrophilic dermal infiltration and systemic inflammatory symptoms. A significant proportion of cases is malignancy associated. Hematologic neoplasms, particularly acute myeloid leukemia and myelodysplastic syndromes, are the most commonly associated malignant conditions. Here, we describe the first case of clinical remission of refractory Sweet's syndrome following hypomethylating therapy with azacytidine in a patient with myelodysplastic syndrome who concurrently obtained a complete hematologic response

Molecular cytogenetic lesions in chronic lymphocytic leukemia

Molecular cytogenetic lesions in CLL

Erratum to: Circulating endothelial cells in patients with chronic lymphocytic leukemia: Clinical-prognostic and biologic significance (Cancer (2010) 116, (1926-37))

[No abstract available