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991.
García-García José Carlos García-Ródenas Ricardo Codina Esteve 《Optimization and Engineering》2020,21(3):1053-1093
Optimization and Engineering - Most parallel surrogate-based optimization algorithms focus only on the mechanisms for generating multiple updating points in each cycle, and rather less attention... 相似文献
992.
Diego Erena Jesús Vzquez Valeo Carlos Navarro Jaime Domínguez 《Fatigue & Fracture of Engineering Materials & Structures》2020,43(1):149-161
Fatigue failure of cables and strands is a common and complex problem. Failure is typically caused by different combinations of time‐variable bending and axial forces. In addition to these loads, contact stresses between wires may play an important role in the fatigue failure of cables. The present work aims to provide deep insight into the fatigue failure of a seven‐wire stainless steel strand subjected to a combination of variable axial and bending loads. To avoid side effects in the analysis, fatigue failure of the strand close to the clamps is prevented. Several tests were performed with a new device specifically designed to avoid failure near the clamps. Thus, failure is always produced at the middle length of the specimen. Test simulations were performed by employing the finite element method. The numerical results were validated via comparisons with experimental data. Finally, life prediction curves were obtained. 相似文献
993.
Irvin Pérez Márcio Muniz de Farias Manuel Castro Roberto Roselló Carlos Recarey Morfa Liosber Medina E. Oñate 《International journal for numerical methods in engineering》2019,118(3):121-131
A novel algorithm to reproduce the arrangement of grains in polycrystalline materials was recently published by the authors. In this original approach, a dense package of circles (or spheres) with the same distribution as the grains is generated to produce a set of Voronoi cells that are later modified to Laguerre cells representing the original structure. This algorithm was successfully applied to materials with somewhat equidimensional grains; however, it fails for long-shaped grains. In this paper, modifications are provided in order to overcome these drawbacks. This is accomplished by moving each vertex of the Voronoi cells in such a way that the vertex should be equidistant from the particles with respect to the Euclidean distance. The algorithm is applied to packages of ellipses and spherocylinders in 2D. An example for a package of spheres is also provided to illustrate the application for a simple 3D case. The adherence between the generated packages and the corresponding tessellations is verified by means of the Jaccard coefficient (J). Several packages are generated randomly and the distribution of J coefficients is investigated. The obtained values satisfy the theoretical restraints and the quality of the proposed algorithm is statistically validated. 相似文献
994.
Susana Díaz‐Amaya Min Zhao Li‐Kai Lin Carlos Ostos Jan P. Allebach George T.‐C. Chiu Amanda J. Deering Lia A. Stanciu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(24)
The increasing incidence of infectious outbreaks from contaminated food and water supply continues imposing a global burden for food safety, creating a market demand for on‐site, disposable, easy‐to‐use, and cost‐efficient devices. Despite of the rapid growth of biosensors field and the generation of breakthrough technologies, more than 80% of the platforms developed at lab‐scale never will get to meet the market. This work aims to provide a cost‐efficient, reliable, and repeatable approach for the detection of foodborne pathogens in real samples. For the first time an optimized inkjet printing platform is proposed taking advantage of a carefully controlled nanopatterning of novel carboxyl‐functionalized aptameric ink on a nitrocellulose substrate for the highly efficient detection of E. coli O157:H7 (25 colony forming units (CFU) mL?1 in pure culture and 233 CFU mL?1 in ground beef) demonstrating the ability to control the variation within ±1 SD for at least 75% of the data collected even at very low concentrations. From the best of the knowledge this work reports the lowest limit of detection of the state of the art for paper‐based optical detection of E. coli O157:H7, with enough evidence (p > 0.05) to prove its high specificity at genus, species, strain, and serotype level. 相似文献
995.
Simone Aparecida da Silva Lincoln Brum de Leite Gusmão Pinheiro Yuri Aparecido Opata João Frederico Haas Leandro Monteiro Francisco Carlos Serbena Gelson Biscaia de Souza Ezequiel Costa Siqueira Alcione Roberto Jurelo 《Journal of Superconductivity and Novel Magnetism》2018,31(8):2363-2372
This paper reports a study on the mechanical and tribological properties of ab- and a (b) c?planes of YBa2Cu3O7?δ single crystals. The single crystals were grown using a CuO-BaO self-flux method. The oxygenation effect on the mechanical and tribological properties of ab- and a (b) c?planes is reported. For the ab- plane, the hardness and elastic modulus were around 6 and 50 GPa, respectively. In this case, significant differences were not observed among the hardness and elastic modulus at different oxygenation states. However, the hardness and elastic modulus for as-grown and oxygenated YBa2Cu3O7?δ single crystals were different from that of the a (b) c?plane, and were observed to be slightly higher for the as-grown than for the oxygenated samples. For as-grown and oxygenated samples, we observed hardness values around 4.7 and 2.0 GPa, respectively. Regarding the elastic modulus, the values were 75 and 40 GPa, respectively. The indentation fracture toughness values on the ab- plane for the as-grown and oxygenated YBa2Cu3O7?δ single crystal were 3.7 ± 1.2 and 2.9 ± 1.2 MPa m1/2, respectively. For the ab- plane, the scratch resistance of the as-grown sample was higher than that of the oxygenated sample and the scratches under load were deeper for the oxygenated sample. As regards the a (b) c?plane, the scar features were seemingly constant through all the scratch lengths and the scratches under load were deeper and larger for the oxygenated than that for the as-grown sample. 相似文献
996.
Ehsan Akbari Molly Y. Mollica Christopher R. Lucas Sarah M. Bushman Randy A. Patton Melika Shahhosseini Jonathan W. Song Carlos E. Castro 《Advanced materials (Deerfield Beach, Fla.)》2017,29(46)
A specific and reversible method is reported to engineer cell‐membrane function by embedding DNA‐origami nanodevices onto the cell surface. Robust membrane functionalization across epithelial, mesenchymal, and nonadherent immune cells is achieved with DNA nanoplatforms that enable functions including the construction of higher‐order DNA assemblies at the cell surface and programed cell–cell adhesion between homotypic and heterotypic cells via sequence‐specific DNA hybridization. It is anticipated that integration of DNA‐origami nanodevices can transform the cell membrane into an engineered material that can mimic, manipulate, and measure biophysical and biochemical function within the plasma membrane of living cells. 相似文献
997.
Carlos M. Poventud-Estrada Raúl Acevedo Camila Morales Luis Betancourt Diana C. Diaz Manuel A. RodriguezIII Eduardo Larios Miguel José-Yacaman Eduardo Nicolau Michael Flynn Carlos R. Cabrera 《Microgravity science and technology》2017,29(5):381-389
The effect of microgravity on the electrochemical oxidation of ammonia at platinum nanoparticles supported on modified mesoporous carbons (MPC) with three different pore diameters (64, 100, and 137 Å) was studied via the chronoamperometric technique in a half-cell. The catalysts were prepared by a H2 reductive process of PtCl\(_{6}^{\mathrm {4-}}\) in presence of the mesoporous carbon support materials. A microgravity environment was obtained with an average gravity of less than 0.02 g created aboard an airplane performing parabolic maneuvers. Results show the chronoamperommetry of the ammonia oxidation reaction in 1.0 M NH4OH at 0.60 V vs. RHE under microgravity conditions. The current density, in all three catalysts, decreased while in microgravity conditions when compared to ground based experiments. Under microgravity, all three catalysts yielded a decrease in ammonia oxidation reaction current density between 25 to 63% versus terrestrial experimental results, in time scales between 1 and 15 s. The Pt catalyst prepared with mesoporous carbon of 137 Å porous showed the smallest changes, between 25 to 48%. Nanostructuring catalyst materials have an effect on the level of current density decrease under microgravity conditions. 相似文献
998.
Juan Carlos Gonzalez-Rosillo Moran Balaish Zachary D. Hood Neel Nadkarni Dimitrios Fraggedakis Kun Joong Kim Kaitlyn M. Mullin Reto Pfenninger Martin Z. Bazant Jennifer L. M. Rupp 《Advanced materials (Deerfield Beach, Fla.)》2020,32(9):1907465
Specialized hardware for neural networks requires materials with tunable symmetry, retention, and speed at low power consumption. The study proposes lithium titanates, originally developed as Li-ion battery anode materials, as promising candidates for memristive-based neuromorphic computing hardware. By using ex- and in operando spectroscopy to monitor the lithium filling and emptying of structural positions during electrochemical measurements, the study also investigates the controlled formation of a metallic phase (Li7Ti5O12) percolating through an insulating medium (Li4Ti5O12) with no volume changes under voltage bias, thereby controlling the spatially averaged conductivity of the film device. A theoretical model to explain the observed hysteretic switching behavior based on electrochemical nonequilibrium thermodynamics is presented, in which the metal-insulator transition results from electrically driven phase separation of Li4Ti5O12 and Li7Ti5O12. Ability of highly lithiated phase of Li7Ti5O12 for Deep Neural Network applications is reported, given the large retentions and symmetry, and opportunity for the low lithiated phase of Li4Ti5O12 toward Spiking Neural Network applications, due to the shorter retention and large resistance changes. The findings pave the way for lithium oxides to enable thin-film memristive devices with adjustable symmetry and retention. 相似文献
999.
Heat Capacity and Thermal Damping Properties of Spin-Crossover Molecules: A New Look at an Old Topic
Karl Ridier Yuteng Zhang Mario Piedrahita-Bello Carlos M. Quintero Lionel Salmon Gábor Molnár Christian Bergaud Azzedine Bousseksou 《Advanced materials (Deerfield Beach, Fla.)》2020,32(21):2000987
The thermally induced spin-crossover (SCO) phenomenon in transition metal complexes is an entropy-driven process, which has been extensively studied through calorimetric methods. Yet, the excess heat capacity associated with the molecular spin-state switching has never been explored for practical applications. Herein, the thermal damping effect of an SCO film is experimentally assessed by monitoring the transient heating response of SCO-coated metallic microwires, Joule-heated by current pulses. A damping of the wire temperature, up to 10%, is evidenced on a time scale of tens of microseconds due to the spin-state switching of the molecular film. Fast heat-charging dynamics and negligible fatigability are demonstrated, which, together with the solid-solid nature of the spin transition, appear as promising features for achieving thermal energy management applications in functional devices. 相似文献
1000.
Simone Gervasoni Anastasia Terzopoulou Carlos Franco Andrea Veciana Norman Pedrini Jan T. Burri Carmela de Marco Erdem C. Siringil Xiang-Zhong Chen Bradley J. Nelson Josep Puigmartí-Luis Salvador Pané 《Advanced materials (Deerfield Beach, Fla.)》2020,32(52):2005652
Sugars are ubiquitous in food, and are among the main sources of energy for almost all forms of life. Sugars can also form structural building blocks such as cellulose in plants. Because of their inherent degradability and biocompatibility characteristics, sugars are compelling materials for transient devices. Here, an additive manufacturing approach for the production of magnetic sugar-based composites is introduced. First, it is shown that sugar-based 3D architectures can be 3D printed by selective laser sintering. This method enables not only the caramelization chemistry but also the mechanical properties of the sugar architectures to be adjusted by varying the laser energy. It is also demonstrated that mixtures of sugar and magnetic particles can be processed as 3D composites. As a proof of concept, a sugar-based millimeter-scale helical swimmer, which is capable of corkscrew motion in a solution with a viscosity comparable to those of biological fluids, is fabricated. The millirobot quickly dissolves in water, while being manipulated through magnetic fields. The present fabrication method can pave the way to a new generation of transient sugar-based small-scale robots for minimally invasive procedures. Due to their rapid dissolution, sugars can be used as an intermediate step for transporting swarms of particles to specific target locations. 相似文献