59 research outputs found
Nanoengineering high-performance metallic thin films with large and tunable mechanical properties
No full textInternational audienceThe current trend toward miniaturization in devices components in key technologies such as micro-/nanoelectronics, energy production, sensors and wear protection requires the development of high-performance nanostructured films with superior mechanical properties. Especially, mutually excluding mechanical properties such as high yield strength and ductility need to be combined, but also high adhesion with the substrate and large fatigue resistance. In order to trigger microstructure-induced material properties, control of the micro-scale structure, atomic composition, average grain size, and layer/film thickness must be optimized based on nanoengineering design concepts. In addition, measuring the properties of thin films (thickness ≤1 m) requires the development of novel techniques capable to probe their mechanical behavior[1]. Here, I will present recent results for several class of advanced thin film materials including nanostructured metallic glasses (ZrCu, ZrCuAl…)[2-4] high entropy alloys (CoCuCrFeNi, Al/CoCuCrFeNi) and multilayers (fully amorphous, amorphous/crystalline, FCC/BCC)[5], highlighting how the control of micro-structure affect the and micro-scale mechanical behavior and enable ultimate mechanical properties. Special emphasis will also be dedicated to present several cutting-edge techniques used to extract the mechanical/electrical behavior at the micro- and nanometer scale, involving, in situ SEM nanoindentation, micro-pillar compression, and tensile test in situ TEM. Finally, I will present recent developments within LSPM, highlighting new research activities dealing with the synthesis of nanostructured metallic films and the development of a new platform for in situ SEM mechanical-electrical characterization.References [1] J. Ast, M. Ghidelli, K. Durst, M. Goeken, M. Sebastiani, A.M. Korsunsky, A review of experimental approaches to fracture toughness evaluation at the micro-scale, Mater. Design 173 (2019) 107762.[2] M. Ghidelli, A. Orekhov, A.L. Bassi, G. Terraneo, P. Djemia, G. Abadias, M. Nord, A. Béché, N. Gauquelin, J. Verbeeck, J.-P. Raskin, D. Schryvers, T. Pardoen, H. Idrissi, Novel class of nanostructured metallic glass films with superior and tunable mechanical properties, Acta Mater. 213 (2021) 116955.[3] C. Poltronieri, A. Brognara, F. Bignoli, S. Evertz, P. Djemia, D. Faurie, F. Challali, C. Li, L. Belliard, G. Dehm, J.P. Best, M. Ghidelli, Mechanical properties and thermal stability of ZrCuAlx thin film metallic glasses: Experiments and first-principle calculations, Acta Mater. 258 (2023) 119226.[4] A. Brognara, J.P. Best, P. Djemia, D. Faurie, G. Dehm, M. Ghidelli, Effect of composition and nanostructure on the mechanical properties and thermal stability of Zr100-xCux thin film metallic glasses, Mater. Design 219 (2022) 110752.[5] G. Wu, C. Liu, A. Brognara, M. Ghidelli, Y. Bao, S. Liu, X. Wu, W. Xia, H. Zhao, J. Rao, D. Ponge, V. Devulapalli, W. Lu, G. Dehm, D. Raabe, Z. Li, Symbiotic crystal-glass alloys via dynamic chemical partitioning, Mater. Today 51 (2021) 6-14
Tailoring compositional and microstructural heterogeneities in metallic glass and high entropy alloy thin films to achieve large and mutually exclusive mechanical properties
No full textInternational audienceThe current trend toward miniaturization in devices components in key technologies such as micro-/nanoelectronics, energy production, sensors and wear protection requires the development of high-performance nanostructured films with superior mechanical properties. Especially, mutually excluding mechanical properties such as high yield strength and ductility need to be combined, but also high adhesion with the substrate and large fatigue resistance. In order to trigger microstructure-induced material properties, control of the micro-scale structure, atomic composition, average grain size, and layer/film thickness must be optimized based on nanoengineering design concepts. Here, I will present recent results for several class of advanced thin film materials including nanostructured metallic glasses (ZrCu/O, ZrCuAl/O…)[1-3] high entropy alloys (CoCuCrFeNi, Al/CoCuCrFeNi) and nanolaminates (fully amorphous, amorphous/crystalline, FCC/BCC)[4, 5], highlighting how the control of micro-structure affect the and micro-scale mechanical behavior and enable ultimate mechanical properties.Among the main results, I will present the potential of Pulsed Laser Deposition (PLD)[1] as a novel technique to synthetize nanostructured cluster-assembled ZrCu, ZrCuAl/O, and CoCuCrFeNi films, reaching ultimate yield strength (>4 GPa) and ductility (>15 %) for ZrCuAl/O films. I will show how controlling of the sublayer thickness (from 100 down to 5 nm) in fully amorphous nanolaminates influences the deformation behavior, suppressing the shear bands formation, while tuning the mechanical properties with mutual combination of large ductility (>10%) and yields strength (>2.5 GPa)[5]. Additionally, I will discuss the synthesis of alternating CrCoNi (crystalline)/TiZrNbHf (amorphous) nanolayers results in an high yield strength (3.6 GPa) and homogeneous deformation (~15%)[4].Finally, I will present recent developments within LSPM, highlighting new research activities dealing with the synthesis of nanostructured metallic films and the development of a new platform for in situ SEM mechanical-electrical characterization.References [1] M. Ghidelli, A. Orekhov, A.L. Bassi, G. Terraneo, P. Djemia, G. Abadias, M. Nord, A. Béché, N. Gauquelin, J. Verbeeck, J.-P. Raskin, D. Schryvers, T. Pardoen, H. Idrissi, Novel class of nanostructured metallic glass films with superior and tunable mechanical properties, Acta Mater. 213 (2021) 116955 doi:10.1016/j.actamat.2021.116955.[2] C. Poltronieri, A. Brognara, F. Bignoli, S. Evertz, P. Djemia, D. Faurie, F. Challali, C. Li, L. Belliard, G. Dehm, J.P. Best, M. Ghidelli, Mechanical properties and thermal stability of ZrCuAlx thin film metallic glasses: Experiments and first-principle calculations, Acta Mater. 258 (2023) 119226 doi:10.1016/j.actamat.2023.119226.[3] A. Brognara, J.P. Best, P. Djemia, D. Faurie, G. Dehm, M. Ghidelli, Effect of composition and nanostructure on the mechanical properties and thermal stability of Zr100-xCux thin film metallic glasses, Mater. Design 219 (2022) 110752 doi:0.1016/j.matdes.2022.110752.[4] G. Wu, C. Liu, A. Brognara, M. Ghidelli, Y. Bao, S. Liu, X. Wu, W. Xia, H. Zhao, J. Rao, D. Ponge, V. Devulapalli, W. Lu, G. Dehm, D. Raabe, Z. Li, Symbiotic crystal-glass alloys via dynamic chemical partitioning, Mater. Today 51 (2021) 6-14 doi:10.1016/j.mattod.2021.10.025.[5] A. Brognara, A. Kashiwar, C. Jung, X. Zhang, A. Ahmadian, N. Gauquelin, J. Verbeeck, P. Djemia, D. Faurie, G. Dehm, H. Idrissi, J.P. Best, M. Ghidelli, Tailoring Mechanical Properties and Shear Band Propagation in ZrCu Metallic Glass Nanolaminates Through Chemical Heterogeneities and Interface Density, Small Struct. (2024) 2400011 doi:doi.org/10.1002/sstr.202400011
Boosting mechanical properties of metallic thin films through advanced nanoengineered design strategies
No full textInternational audienceThe current trend toward miniaturization in devices components in key technologies such as micro-/nanoelectronics, energy production, sensors and wear protection requires the development of high-performance nanostructured films with superior mechanical properties. Especially, mutually excluding mechanical properties such as high yield strength and ductility need to be combined, but also high adhesion with the substrate and large fatigue resistance. In order to trigger microstructure-induced material properties, control of the micro-scale structure, atomic composition, average grain size, and layer/film thickness must be optimized based on nanoengineering design concepts. Here, I will present recent results for several class of advanced thin film materials including nanostructured metallic glasses (ZrCu/O, ZrCuAl/O…)[1-3] high entropy alloys (CoCuCrFeNi, Al/CoCuCrFeNi) and multilayers (fully amorphous, amorphous/crystalline, FCC/BCC)[4], highlighting how the control of micro-structure affect the and micro-scale mechanical behavior and enable ultimate mechanical properties.Among the main results, I will present the potential of Pulsed Laser Deposition (PLD)[1] as a novel technique to synthetize nanostructured cluster-assembled ZrCu, ZrCuAl/O, and CoCuCrFeNi films, reaching ultimate yield strength (>4 GPa) and ductility (>15 %) for ZrCuAl/O films. I will show how controlling of the sublayer thickness (from 100 down to 5 nm) in fully amorphous nanolaminates influences the deformation behavior, suppressing the shear bands formation, while tuning the mechanical properties with mutual combination of large ductility (>10%) and yields strength (>2.5 GPa). Additionally, I will discuss the synthesis of alternating CrCoNi (crystalline)/TiZrNbHf (amorphous) nanolayers results in an high yield strength (3.6 GPa) and homogeneous deformation (~15%)[4].Finally, I will present recent developments within LSPM, highlighting new research activities dealing with the synthesis of nanostructured metallic films and the development of a new platform for in situ SEM mechanical-electrical characterization.References [1] M. Ghidelli, A. Orekhov, A.L. Bassi, G. Terraneo, P. Djemia, G. Abadias, M. Nord, A. Béché, N. Gauquelin, J. Verbeeck, J.-P. Raskin, D. Schryvers, T. Pardoen, H. Idrissi, Novel class of nanostructured metallic glass films with superior and tunable mechanical properties, Acta Mater. 213 (2021) 116955 [2] C. Poltronieri, A. Brognara, F. Bignoli, S. Evertz, P. Djemia, D. Faurie, F. Challali, C. Li, L. Belliard, G. Dehm, J.P. Best, M. Ghidelli, Mechanical properties and thermal stability of ZrCuAlx thin film metallic glasses: Experiments and first-principle calculations, Acta Mater. 258 (2023) 119226 [3] A. Brognara, J.P. Best, P. Djemia, D. Faurie, G. Dehm, M. Ghidelli, Effect of composition and nanostructure on the mechanical properties and thermal stability of Zr100-xCux thin film metallic glasses, Mater. Design 219 (2022) 110752 [4] G. Wu, C. Liu, A. Brognara, M. Ghidelli, Y. Bao, H. Zhao, J. Rao, D. Ponge, V. Devulapalli, W. Lu, G. Dehm, D. Raabe, Z. Li, Symbiotic crystal-glass alloys via dynamic chemical partitioning, Mater. Today 51 (2021) 6-1
Ruolo patogenetico delle alterazioni emocoagulative nell'insorgenza di s poliabortiva e di patologie ostetriche
No full textDevelopment of an eye-tracking method for diagnosing Delirium: assessing cognitive function and autonomic nervous system activity
No full textTowards new multielemental thin film metallic glasses with enhanced mechanical properties and thermal stability
No full textInternational audienceBulk Metallic Glasses (BMGs) have been object of large scientific research due to their outstanding mechanical properties such as high hardness and yield strength up to 7 and 2 GPa, respectively as a result of their amorphous atomic structure [1, 2].However, their major drawback is the low ductility and brittle failure caused by the formation of shear bands.Nevertheless, this weakness can be overcome by reducing the intrinsic length scale of the specimen down to the submicrometric scale activating mechanical size effects, which prevent the formation of shear bands, while increasing the mechanical properties.For instance, thin film metallic glasses (TFMGs, thickness <1m) reported a yield strength up to ~4 GPa, large ductility with the suppression of formation of shear bands with promising applications as scratch and wear resistant coatings as well as for stretchable electronics [2, 3].However, there are still many challenges in the study of TFMGs involving the effect of composition on the glass forming ability and on mechanical properties, while the synthesis of novel microstructures (e.g. multilayers, nanogranular films etc.) with even boosted mechanical properties and thermal stability are still an open scientific domain.In this context, the objective of my PhD research (within the framework of a Vinci project sponsored by the Université Franco-Italienne) is to investigate the mechanical properties and thermal stability of ZrCu-based TFMGs alloys with different compositions and thicknesses, while exploiting pulsed laser deposition (PLD) as a novel technique enabling to accurately control the nanoscale morphology of the film [4]. Up to now, we have deposited ZrCu and ZrCuAl TFMGs by PLD with different contents of Al (%at.) as well as with compact and nanogranular morphology. Films have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), while we are currently investigating the mechanical properties by using Brillouin light scattering and tensile tests on polymeric substrates.1.Pan D., et al., Experimental characterization of shear transformation zones for plastic flow of bulk metallic glasses. Proceedings of the National Academy of Sciences, 2008. 105(39): p. 14769-14772.2.Tian L., et al., Approaching the ideal elastic limit of metallic glasses. Nature Communications, 2012. 3(1): p. 609.3.Ghidelli M., et al., Homogeneous flow and size dependent mechanical behavior in highly ductile Zr65Ni35 metallic glass films. Acta Materialia, 2017. 131: p. 246-259.4.M. Ghidelli, A.O., A. Li Bassi, G. Terraneo, P. Djemia, G. Abadias, M. Nord, A. Béché, N. Gauquelin, J. Verbeeck, J.-P. Raskin, D. Schryvers, T. Pardoen, H. Idrissi, Novel class of nanostructured metallic glass films with superior and tunable mechanical properties. Acta Materialia, 2021. 213: p. 9
Long-term follow up in Acquired Hemophilia A: clinical courses and outcomes observed in a single Hemophilia Centre
No full textHaemarthroses and arthropathy in mild/moderate haemophilia: data collected from a single Haemophilia Centre, Pavia, Italy
No full textDevelopment of an Eye-Tracking Method for Diagnosing Delirium: Assessing Cognitive Function and Autonomic Nervous System Activity
No full textDelirium is a severe neuro-psychiatric condition characterized by a global deterioration of cognitive functions. The Confusion Assessment Method for the Intensive Care Unit scale, a test that evaluates a patient's cognitive abilities, is currently the most recommended method for assessing suspected delirium in intensive care units. However, this method faces challenges such as inadequate staff training, patient cooperation difficulties, and a lack of measurable quantitative metrics. While there are existing tests in the literature that use eye tracking to evaluate cognitive functions and assess the autonomic nervous system, there is currently no specific test available based on wearable eye tracking for diagnosing delirium. In this study, we investigated the application of a test to evaluate cognitive function and autonomic nervous system activity using eye tracking. The proposed protocol consists of four tests: the blank test, pro- and anti-saccade tests, and pupillometry test. In the first three tests, visual stimuli are presented to the subjects, and an algorithm has been developed to calculate their reaction times, which is the time interval from the presentation of the stimulus to the completion of the task. The extended uncertainty with a 95% confidence level introduced by the algorithm has been estimated as 12 ms using the Monte Carlo method. In the pupillometry test, a temporary light stimulus is provided, and parameters related to the pupil light reflex are calculated. The tests were conducted on a sample of 17 healthy male subjects, aged between 21 and 28 years, without visual or cognitive impairments. The results provide an overview of the cognitive functions and autonomic nervous system activity in the examined subjects. Additionally, the data collected from healthy subjects can be compared with individuals affected by delirium in future studies. To validate the reaction time algorithm, the Monte Carlo method was used, and a statistical analysis was conducted on the output data. The evaluation of the algorithm for detecting reaction times shows a root mean square error of 6 ms. The results of the pro- and anti-saccade tests show a statistically significant difference in detected reaction times (p-value ! 0.05), with the latter being higher due to the increased cognitive load required. The pupillometry test measured pupil light reflex parameters and compared them with those reported in the literature
Plasma exchange and immunosuppressive therapy in a case of mild haemophilia A with inhibitors and a life-threatening lower limb haemorrhage.
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