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result(s) for
"Saiz, Eduardo"
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Super-tough MXene-functionalized graphene sheets
2020
Flexible reduced graphene oxide (rGO) sheets are being considered for applications in portable electrical devices and flexible energy storage systems. However, the poor mechanical properties and electrical conductivities of rGO sheets are limiting factors for the development of such devices. Here we use MXene (M) nanosheets to functionalize graphene oxide platelets through Ti-O-C covalent bonding to obtain MrGO sheets. A MrGO sheet was crosslinked by a conjugated molecule (1-aminopyrene-disuccinimidyl suberate, AD). The incorporation of MXene nanosheets and AD molecules reduces the voids within the graphene sheet and improves the alignment of graphene platelets, resulting in much higher compactness and high toughness. In situ Raman spectroscopy and molecular dynamics simulations reveal the synergistic interfacial interaction mechanisms of Ti-O-C covalent bonding, sliding of MXene nanosheets, and π-π bridging. Furthermore, a supercapacitor based on our super-tough MXene-functionalized graphene sheets provides a combination of energy and power densities that are high for flexible supercapacitors.
Poor mechanical properties of reduced graphene oxide sheets hinder development of flexible energy storage systems. MXene functionalised graphene oxide with Ti-O-C bonding and additional crosslinking is here reported to dramatically increase toughness for flexible supercapacitors.
Journal Article
3D Printing Bioinspired Ceramic Composites
by
García-Tuñón, Esther
,
Giuliani, Finn
,
Zhang, Qinghua
in
639/301/1023/1024
,
639/301/1023/1025
,
Composite materials
2017
Natural structural materials like bone and shell have complex, hierarchical architectures designed to control crack propagation and fracture. In modern composites there is a critical trade-off between strength and toughness. Natural structures provide blueprints to overcome this, however this approach introduces another trade-off between fine structural manipulation and manufacturing complex shapes in practical sizes and times. Here we show that robocasting can be used to build ceramic-based composite parts with a range of geometries, possessing microstructures unattainable by other production technologies. This is achieved by manipulating the rheology of ceramic pastes and the shear forces they experience during printing. To demonstrate the versatility of the approach we have fabricated highly mineralized composites with microscopic Bouligand structures that guide crack propagation and twisting in three dimensions, which we have followed using an original
in-situ
crack opening technique. In this way we can retain strength while enhancing toughness by using strategies taken from crustacean shells.
Journal Article
Freezing as a Path to Build Complex Composites
by
Deville, Sylvain
,
Nalla, Ravi K.
,
Saiz, Eduardo
in
Biocompatible Materials
,
Biomaterials
,
Bone Regeneration
2006
Materials that are strong, ultralightweight, and tough are in demand for a range of applications, requiring architectures and components carefully designed from the micrometer down to the nanometer scale. Nacre, a structure found in many molluscan shells, and bone are frequently used as examples for how nature achieves this through hybrid organic-inorganic composites. Unfortunately, it has proven extremely difficult to transcribe nacre-like clever designs into synthetic materials, partly because their intricate structures need to be replicated at several length scales. We demonstrate how the physics of ice formation can be used to develop sophisticated porous and layered-hybrid materials, including artificial bone, ceramic-metal composites, and porous scaffolds for osseous tissue regeneration with strengths up to four times higher than those of materials currently used for implantation.
Journal Article
Using graphene networks to build bioinspired self-monitoring ceramics
2017
The properties of graphene open new opportunities for the fabrication of composites exhibiting unique structural and functional capabilities. However, to achieve this goal we should build materials with carefully designed architectures. Here, we describe the fabrication of ceramic-graphene composites by combining graphene foams with pre-ceramic polymers and spark plasma sintering. The result is a material containing an interconnected, microscopic network of very thin (20–30 nm), electrically conductive, carbon interfaces. This network generates electrical conductivities up to two orders of magnitude higher than those of other ceramics with similar graphene or carbon nanotube contents and can be used to monitor ‘
in situ
’ structural integrity. In addition, it directs crack propagation, promoting stable crack growth and increasing the fracture resistance by an order of magnitude. These results demonstrate that the rational integration of nanomaterials could be a fruitful path towards building composites combining unique mechanical and functional performances.
Micro- and nanostructures found in nature can be adopted to new uses and materials in engineered composites. Here authors demonstrate large enhancements in toughness and electrical conductivity in a ceramic upon addition of graphene at low (1 volume %) levels.
Journal Article
Real-time insight into the multistage mechanism of nanoparticle exsolution from a perovskite host surface
2023
In exsolution, nanoparticles form by emerging from oxide hosts by application of redox driving forces, leading to transformative advances in stability, activity, and efficiency over deposition techniques, and resulting in a wide range of new opportunities for catalytic, energy and net-zero-related technologies. However, the mechanism of exsolved nanoparticle nucleation and perovskite structural evolution, has, to date, remained unclear. Herein, we shed light on this elusive process by following in real time Ir nanoparticle emergence from a SrTiO
3
host oxide lattice, using in situ high-resolution electron microscopy in combination with computational simulations and machine learning analytics. We show that nucleation occurs via atom clustering, in tandem with host evolution, revealing the participation of surface defects and host lattice restructuring in trapping Ir atoms to initiate nanoparticle formation and growth. These insights provide a theoretical platform and practical recommendations to further the development of highly functional and broadly applicable exsolvable materials.
The separation of nanoparticles from oxide hosts by exsolution forms the basis for catalytic and energy-related applications. Here, the authors elucidate the multistep mechanism of exsolution at perovskite surfaces by combining real-time electron microscopy and computational methods.
Journal Article
Solution-sheared supramolecular oligomers with enhanced thermal resistance in interfacial adhesion and bulk cohesion
2025
Developing strong, thermally resistant adhesives for load-bearing applications remains challenging. Here we report a class of solution-sheared supramolecular oligomers that exhibit exceptional adhesive strength and toughness across a broad temperature range. These adhesives achieve a debonding work up to 23.6 kN/m and a lap shear strength exceeding 30.6 MPa, surpassing commercial structural adhesives by up to eightfold on metal and glass surfaces. Impressively, they retain a lap shear strength above 21 MPa even at 120 °C, outperforming current leading commercial alternatives. This performance arises from hierarchical nanostructures formed during solution shearing, which create enlarged, ordered nanocrystals and aligned nanofibrils within the bulk, enhancing mechanical robustness and toughness. Simultaneously, hydrogen-bonded nanocrystals anchored at the surface significantly strengthen interfacial adhesion. This multiscale structural organization enables thermal tolerance, crack resistance, and efficient energy dissipation, setting a new paradigm for high-performance, reusable adhesives capable of multiple rebonding cycles. Our work demonstrates how solution-shearing simultaneously optimizes adhesion chemistry and multiscale nano/microstructural control, achieving synergistic improvements in interfacial adhesion and bulk cohesion.
Developing strong, thermally resistant adhesives for load-bearing applications remains challenging. Here, the authors report a class of solution-sheared supramolecular oligomers that exhibit exceptional adhesive strength and toughness across a broad temperature range.
Journal Article
3-D printing of chitosan-calcium phosphate inks: rheology, interactions and characterization
by
Maire, Eric
,
Delair, Thierry
,
Grémillard, Laurent
in
3-D printers
,
Apatite
,
Aqueous solutions
2019
Bone substitute fabrication is of interest to meet the worldwide incidence of bone disorders. Physical chitosan hydrogels with intertwined apatite particles were chosen to meet the bio-physical and mechanical properties required by a potential bone substitute. A set up for 3-D printing by robocasting was found adequate to fabricate scaffolds. Inks consisted of suspensions of calcium phosphate particles in chitosan acidic aqueous solution. The inks are shear-thinning and consist of a suspension of dispersed platelet aggregates of dicalcium phosphate dihydrate in a continuous chitosan phase. The rheological properties of the inks were studied, including their shear-thinning characteristics and yield stress. Scaffolds were printed in basic water/ethanol baths to induce transformation of chitosan-calcium phosphates suspension into physical hydrogel of chitosan mineralized with apatite. Scaffolds consisted of a chitosan polymeric matrix intertwined with poorly crystalline apatite particles. Results indicate that ink rheological properties could be tuned by controlling ink composition: in particular, more printable inks are obtained with higher chitosan concentration (0.19 mol·L
−1
).
Journal Article
Solutions by Quadratures of Complex Bernoulli Differential Equations and Their Quantum Deformation
by
Fernández-Saiz, Eduardo
,
Campoamor-Stursberg, Rutwig
,
Herranz, Francisco J.
in
Algebra
,
book algebra
,
Canonical forms
2024
It is shown that the complex Bernoulli differential equations admitting the supplementary structure of a Lie–Hamilton system related to the book algebra b2 can always be solved by quadratures, providing an explicit solution of the equations. In addition, considering the quantum deformation of Bernoulli equations, their canonical form is obtained and an exact solution by quadratures is deduced as well. It is further shown that the approximations of kth-order in the deformation parameter from the quantum deformation are also integrable by quadratures, although an explicit solution cannot be obtained in general. Finally, the multidimensional quantum deformation of the book Lie–Hamilton systems is studied, showing that, in contrast to the multidimensional analogue of the undeformed system, the resulting system is coupled in a nontrivial form.
Journal Article
Nature‐Inspired Innovation in Electrical Engineering Technologies and Applications
2025
In the rapidly evolving field of science and technology, biomimetic design has emerged as a transformative force in electrical engineering. Leveraging insights from natural evolution, biomimetic methodologies significantly enhance equipment performance and overall system efficiency. This review explores several key functional mechanisms, such as multimodal sensing, energy conversion, and adaptive drive, and showcases state‐of‐the‐art applications. These include biomimetic sensors and detection systems that mimic natural entities like human epidermis, arachnid receptors, and the complex eyes of insects; actuation and robotic systems inspired by the flexible limbs of octopuses, the versatility of elephant trunks, and the cooperative dynamics of ant colonies; as well as renewable energy technologies derived from plant photosynthesis and microbial energy processes, illustrating their potential to transcend traditional engineering boundaries. This biomimetic design not only advances sensor technology, energy harvesting, and adaptive robotics but also holds revolutionary potential for neuromorphic computing and advanced information processing systems. Additionally, the integration of artificial intelligence in these domains, along with their applications in healthcare, environmental monitoring, and human–computer interaction, is discussed. This work underscores the critical integration of natural inspirations with modern engineering to enhance performance and sustainability, offering insights into the future of biomimetic design in electrical engineering. This review investigates how nature‐inspired design principles revolutionize electrical engineering by translating biological mechanisms, such as sensing, actuation, energy conversion, and neural processing, into advanced intelligent technologies. Through interdisciplinary integration, biomimetic strategies enable efficient, adaptive, and sustainable systems, bridging natural evolution with engineered innovation and redefining the frontier of intelligent, eco‐conscious electrical systems.
Journal Article
Pulmonary Edema in COVID-19 Treated with Furosemide and Negative Fluid Balance (NEGBAL): A Different and Promising Approach
by
Coria, Micaela
,
Rodriguez, Marcelo
,
Alo, Veronica
in
Blood pressure
,
Clinical medicine
,
Coronaviruses
2021
In COVID-19, pulmonary edema has been attributed to “cytokine storm”. However, it is known that SARS-CoV2 promotes angiotensin-converting enzyme 2 deficit, increases angiotensin II, and this triggers volume overload. Our report is based on COVID-19 patients with tomographic evidence of pulmonary edema and volume overload to whom established a standard treatment with diuretic (furosemide) guided by objectives: Negative Fluid Balance (NEGBAL approach). Retrospective observational study. We reviewed data from medical records: demographic, clinical, laboratory, blood gas, and chest tomography (CT) before and while undergoing NEGBAL, from 20 critically ill patients. Once the NEGBAL strategy was started, no patient required mechanical ventilation. All cases reverted to respiratory failure with NEGBAL, but subsequently two patients died from sepsis and acute myocardial infarction (AMI). The regressive analysis between PaO2/FiO2BAL and NEGBAL demonstrated correlation (p < 0.032). The results comparing the Pao2Fio2 between admission to NEGBAL to NEGBAL day 4, were statistically significant (p < 0.001). We noted between admission to NEGBAL and day 4 improvement in CT score (p < 0.001), decrease in the superior vena cava diameter (p < 0.001) and the decrease of cardiac axis (p < 0.001). Though our study has several limitations, we believe the promising results encourage further investigation of this different pathophysiological approach.
Journal Article