Despite lower hardness, stiffness, and resistance to harsh environments, heavy metallic parts and soft polymer-based composites are often preferred to ceramics because they offer higher resilience. ...By contrast, highly mineralized biomaterials combine these properties through hierarchical and heterogeneous architecture. Reproducing these internal designs into synthetic highly mineralized materials would therefore widen their range of application. To this aim, external fields have been used to control the orientation and position of microparticles and build complex architectures. This approach is compatible with most manufacturing processes and provides large flexibility in design. Here, I present an overview of these processes and describe how they can augment the properties of the materials produced. Theoretical and experimental descriptions are detailed to determine the strengths and limitations of each technique. With this knowledge, potential areas of improvement and future research directions will lead to the creation of highly mineralized materials with unprecedented functionalities.
Natural composites are often heterogeneous to fulfil functional demands. Manufacturing analogous materials remains difficult, however, owing to the lack of adequate and easily accessible processing ...tools. Here, we report an additive manufacturing platform able to fabricate complex-shaped parts exhibiting bioinspired heterogeneous microstructures with locally tunable texture, composition and properties, as well as unprecedentedly high volume fractions of inorganic phase (up to 100%). The technology combines an aqueous-based slip-casting process with magnetically directed particle assembly to create programmed microstructural designs using anisotropic stiff platelets in a ceramic, metal or polymer functional matrix. Using quantitative tools to control the casting kinetics and the temporal pattern of the applied magnetic fields, we demonstrate that this approach is robust and can be exploited to design and fabricate heterogeneous composites with thus far inaccessible microstructures. Proof-of-concept examples include bulk composites with periodic patterns of microreinforcement orientation, and tooth-like bilayer parts with intricate shapes exhibiting site-specific composition and texture.
To get nanoscopic and microscopic details, compression, tensile, or crack propagation tests can also be conducted inside a scanning electron microscope (SEM). After calibration procedures to correct ...for thermal expansion of the device itself, control tests were done using standard specimens made of carbon steel. ...the setup was used to stretch at 1150°C a single-crystal Ni superalloy specimen with a notch on its side.
Ceramic materials are ubiquitous in technologies operating under high mechanical, thermal or chemical constrains. Research in ceramic processing aims at creating ceramics with properties that are ...still challenging to obtain, such as toughness, transparency, conductivity, among others. Magnetic slip casting is a process where an external magnetic field is used to createcontrolled texture in ceramics. Over the past 20 years of research on magnetic slip casting, dense and textured ceramics of multiple chemistry were found to exhibit enhanced properties. This paper reviews the progress in the field of magnetic slip casting, details the processing parameters and the textures obtained for a diverse range of compositions. The structural and functional properties of the magnetically textured slip casted and sintered ceramics are presented. This overview of the magnetic slip casting process allows to identify critical directions for future advancement in advanced technical ceramics.
Purpose
To introduce a novel convolutional neural network (CNN)‐based approach for frequency‐and‐phase correction (FPC) of MR spectroscopy (MRS) spectra to achieve fast and accurate FPC of ...single‐voxel MEGA‐PRESS MRS data.
Methods
Two neural networks (one for frequency and one for phase) were trained and validated using published simulated and in vivo MEGA‐PRESS MRS dataset with wide‐range artificial frequency and phase offsets applied. The CNN‐based approach was subsequently tested and compared to the current deep learning solution: multilayer perceptrons (MLP). Furthermore, random noise was added to the original simulated dataset to further investigate the model performance at varied signal‐to‐noise ratio (SNR) levels (i.e., 10, 5, and 2.5). Additional frequency and phase offsets (i.e., small, moderate, large) were also applied to the in vivo dataset, and the CNN model was compared to the conventional approach SR and model‐based SR implementation (mSR).
Results
The CNN model is more robust to noise compared to the MLP‐based approach due to having smaller mean absolute errors in both frequency (0.01 ± 0.01 Hz at SNR = 10 and 0.01 ± 0.02 Hz at SNR = 2.5) and phase (0.12 ± 0.09° at SNR = 10 and −0.07 ± 0.44° at SNR = 2.5) offset prediction. Furthermore, better performance was demonstrated for FPC when compared to the MLP‐based approach, and SR when applied to the in vivo dataset for both with and without additional offsets.
Conclusion
A CNN‐based approach provides a solution to the automated preprocessing of MRS data, and the experimental results demonstrate the quantitatively improved spectra quality compared to the state‐of‐the‐art approach.
Robots and artificial machines have been captivating the public for centuries, depicted first as threats to humanity, then as subordinates and helpers. In the last decade, the booming exposure of ...humans to robots has fostered an increasing interest in soft robotics. By empowering robots with new physical properties, autonomous actuation, and sensing mechanisms, soft robots are making increasing impacts on areas such as health and medicine. At the same time, the public sympathy to robots is increasing. However, there is still a great need for innovation to push robotics toward more diverse applications. To overcome the major limitation of soft robots, which lies in their softness, strategies are being explored to combine the capabilities of soft robots with the performance of hard metallic ones by using composite materials in their structures. After reviewing the major specificities of hard and soft robots, paths to improve actuation speed, stress generation, self-sensing, and actuation will be proposed. Innovations in controlling systems, modeling, and simulation that will be required to use composite materials in robotics will be discussed. Finally, based on recently developed examples, the elements needed to progress toward a new form of artificial life will be described.
In this context, in a study published in a recent issue of Science Advances (doi:10.1126/sciadv.aat4253), an international collaborative team led by Rόisín Owens from the University of Cambridge ...reports the development of a 3D tubular strategy to host and monitor growth of cells in 3D. ...the morphology and number of the cells was monitored by fluorescence microscopy to determine the origin of the changes in electrical conductivity. In the future, Owens’s team will perform electrical stimulation experiments with various cell types, including electroactive cells, and study the effect of various compounds on the fully formed tissues. (a) Three-dimensional T-shaped tubistor in an 8-cm-diameter petri dish, with (b) the electrically conductive porous scaffold placed inside, (c) its microstructure, and (d) with green fluorescent cells.
...a resolution down to 100 nm can be attained. ...when suspended in water in the presence of hydrogen peroxide, a catalytic reaction occurred that liberated oxygen and water and caused the ...propulsion. ...sonication detached the particles from the substrate and centrifugation was used to concentrate them.
Miniaturized and high‐power‐density 3D electronic devices pose new challenges on thermal management. Indeed, prompt heat dissipation in electrically insulating packaging is currently limited by the ...thermal conductivity achieved by thermal interface materials (TIMs) and by their capability to direct the heat toward heat sinks. Here, high thermal conductivity boron nitride (BN)‐based composites that are able to conduct heat intentionally toward specific areas by locally orienting magnetically functionalized BN microplatelets are created using magnetically assisted slip casting. The obtained thermal conductivity along the direction of alignment is unusually high, up to 12.1 W m−1 K−1, thanks to the high concentration of 62.6 vol% of BN in the composite, the low concentration in polymeric binder, and the high degree of alignment. The BN composites have a low density of 1.3 g cm−3, a high stiffness of 442.3 MPa, and are electrically insulating. Uniquely, the approach is demonstrated with proof‐of‐concept composites having locally graded orientations of BN microplatelets to direct the heat away from two vertically stacked heat sources. Rationally designing the microstructure of TIMs to direct heat strategically provides a promising solution for efficient thermal management in 3D integrated electronics.
Using the magnetically assisted slip casting method, microstructures of boron nitride composites are purposely designed and highly oriented to achieve unusually high thermal conductivity and directional heat transfer toward specific areas along the direction of microplatelet alignment, opening up the solutions for the next‐generation thermal management for 3D electronic packaging.
Abstract
The author, a global executive leadership coach, speaker, and author, writes about how she first met Frances Hesselbein as did many other leaders, through the pioneering executive coach ...Marshall Goldsmith. “Even though I’d been advocating for a more empathetic approach when coaching executives,” the author writes, “it was as if Frances brought into sharp focus something that had until then remained fuzzy, broadening and elevating my understanding of leadership to a spiritual level. With a few words, she had just unlocked a door in my mind.” The author’s tribute to Frances concludes: “She made everyone feel seen and heard, putting her ego aside to light a spark in others. The spark she lit in me profoundly shaped my perspective on leadership and my coaching practice. My hope is that I’m in turn unlocking doors for othersࣧdoors to becoming the best version of themselves.”
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