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"Microstructure"
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NODDI: Practical in vivo neurite orientation dispersion and density imaging of the human brain
This paper introduces neurite orientation dispersion and density imaging (NODDI), a practical diffusion MRI technique for estimating the microstructural complexity of dendrites and axons in vivo on clinical MRI scanners. Such indices of neurites relate more directly to and provide more specific markers of brain tissue microstructure than standard indices from diffusion tensor imaging, such as fractional anisotropy (FA). Mapping these indices over the whole brain on clinical scanners presents new opportunities for understanding brain development and disorders. The proposed technique enables such mapping by combining a three-compartment tissue model with a two-shell high-angular-resolution diffusion imaging (HARDI) protocol optimized for clinical feasibility. An index of orientation dispersion is defined to characterize angular variation of neurites. We evaluate the method both in simulation and on a live human brain using a clinical 3T scanner. Results demonstrate that NODDI provides sensible neurite density and orientation dispersion estimates, thereby disentangling two key contributing factors to FA and enabling the analysis of each factor individually. We additionally show that while orientation dispersion can be estimated with just a single HARDI shell, neurite density requires at least two shells and can be estimated more accurately with the optimized two-shell protocol than with alternative two-shell protocols. The optimized protocol takes about 30min to acquire, making it feasible for inclusion in a typical clinical setting. We further show that sampling fewer orientations in each shell can reduce the acquisition time to just 10min with minimal impact on the accuracy of the estimates. This demonstrates the feasibility of NODDI even for the most time-sensitive clinical applications, such as neonatal and dementia imaging.
► Proposed an experimental design and analysis framework for imaging neurite morphology. ► First in vivo demonstration of neurite orientation dispersion and density mapping. ► NODDI estimates disentangle the key factors contributing to fractional anisotropy. ► NODDI protocol is clinically feasible: imaging the whole brain in 30 minutes or less. ► NODDI protocol is simple to implement, consisting of just two HARDI shells.
Journal Article
Dynamical heterogeneities in glasses, colloids, and granular media
\"Most of the solid materials we use in everyday life, from plastics to cosmetic gels exist under a non-crystalline, amorphous form: they are glasses. Yet, we are still seeking a fundamental explanation as to what glasses really are and to why they form. In this book, we survey the most recent theoretical and experimental research dealing with glassy physics, from molecular to colloidal glasses and granular media. Leading experts in this field present broad and original perspectives on one of the deepest mysteries of condensed matter physics, with an emphasis on the key role played by heterogeneities in the dynamics of glassiness\"-- Provided by publisher.
Book
Intelligent drying strategy for ultra-thin ceramic sheet casting based on infrared perception
Currently, the setting of cast drying conditions relies more on the experience of engineers, lacking effective methods for quantitative testing and intelligent control. In this paper, the actual drying process of ultra-thin ceramic sheets using infrared perception during the high-speed casting was investigated. The influence of different drying conditions on the microstructure and properties of ceramic sheets was clarified. The infrared perception results show that there are significant differences between the actual temperatures and the set values. Compared to the set temperature, there is a stronger correlation between the actual temperature and sheet properties. The constant temperature drying period is critical for the formation of sheet microstructure and properties. Finally, a general intelligent drying strategy is proposed to meet the diverse needs of the sheet.
Journal Article
Analysis of enhanced thermal transmission mechanism with microstructures by field synergy theory
This study numerically examines the impact of oblique ribs and staggered herringbone microstructures on the heat transfer performance of microchannels. The results indicate that the Nu x values of the oblique rib (Type A) and staggered herringbone (Type B) microchannels exhibit significantly higher performance compared to smooth rectangular (Type C) microchannels. The oblique ribs and staggered herringbone microstructures improve heat transfer efficiency along the flowing direction, leading to an evident increase followed by horizontal fluctuations in Nu x . In contrast, the Nu x of Type C without microstructures decreases significantly at the inlet and subsequently remains relatively constant. The bottom temperature T w of Type A and B are lower than the temperature of Type C. The results of field cooperation analysis indicate that the synergistic fields of the oblique ribs microchannels primarily exist along both sidewalls, while they are present at the fluid center for the staggered herringbone microchannels. Type A exhibits a slightly stronger heat transfer effect despite having a smaller synergistic area compared to Type B.
Journal Article
The architecture of Recent brachiopod shells: diversity of biocrystal and biopolymer assemblages in rhynchonellide, terebratulide, thecideide and craniide shells
Biological hard tissues are a rich source of design concepts for the generation of advanced materials. They represent the most important library of information on the evolution of life and its environmental conditions. Organisms produce soft and hard tissues in a bottom-up process, a construction principle that is intrinsic to biologically secreted materials. This process emerged early on in the geological record, with the onset of biological mineralization. The phylum Brachiopoda is a marine animal group that has an excellent and continuous fossil record from the early Cambrian to the Recent. Throughout this time interval, the Brachiopoda secreted phosphate and carbonate shells and populated many and highly diverse marine habitats. This required great flexibility in the adaptation of soft and hard tissues to the different marine environments and living conditions. This review presents, juxtaposes and discusses the main modes of mineral and biopolymer organization in Recent, carbonate shell-producing, brachiopods. We describe shell tissue characteristics for taxa of the orders Rhynchonellida, Terebratulida, Thecideida and Craniida. We highlight modes of calcite and organic matrix assembly at the macro-, micro-, and nano-scales based on results obtained by Electron Backscatter Diffraction, Atomic Force Microscopy, Field Emission Scanning Electron Microscopy and Scanning Transmission Electron Microscopy. We show variation in composite hard tissue organization for taxa with different lifestyles, visualize nanometer-scale calcite assemblies for rhynchonellide and terebratulide fibers, highlight thecideide shell microstructure, texture and chemistry characteristics, and discuss the feasibility to use thecideide shells as archives of proxies for paleoenvironment and paleoclimate reconstructions.
Journal Article
3D microstructure design of lithium-ion battery electrodes assisted by X-ray nano-computed tomography and modelling
Driving range and fast charge capability of electric vehicles are heavily dependent on the 3D microstructure of lithium-ion batteries (LiBs) and substantial fundamental research is required to optimise electrode design for specific operating conditions. Here we have developed a full microstructure-resolved 3D model using a novel X-ray nano-computed tomography (CT) dual-scan superimposition technique that captures features of the carbon-binder domain. This elucidates how LiB performance is markedly affected by microstructural heterogeneities, particularly under high rate conditions. The elongated shape and wide size distribution of the active particles not only affect the lithium-ion transport but also lead to a heterogeneous current distribution and non-uniform lithiation between particles and along the through-thickness direction. Building on these insights, we propose and compare potential graded-microstructure designs for next-generation battery electrodes. To guide manufacturing of electrode architectures, in-situ X-ray CT is shown to reliably reveal the porosity and tortuosity changes with incremental calendering steps.
The 3D microstructure of the electrode predominantly determines the electrochemical performance of Li-ion batteries. Here, the authors show that the microstructural heterogeneities lead to non-uniform Li insertion and current distribution while graded-microstructures improve the performance.
Journal Article
DREAM.3D: A Digital Representation Environment for the Analysis of Microstructure in 3D
This paper presents a software environment for processing, segmenting, quantifying, representing and manipulating digital microstructure data. The paper discusses the approach to building a generalized representation strategy for digital microstructures and the barriers encountered when trying to integrate a set of existing software tools to create an expandable codebase.
Journal Article
A review on the recent advances concerning the fatigue performance of titanium alloys for orthopedic applications
This article presents a review on recent advances in the fatigue behavior of Ti alloys, especially the main commercial compositions for orthopedic applications. In the case of well-known Ti–6Al–4V alloy, the major concern is related to the effect of the surface modification necessary to improve the osseointegration. The introduction of surface discontinuities due to the growth of a porous oxide layer, or the roughness development, may severely affect the fatigue performance depending on the level of alteration. In the case of additive manufactured Ti–6Al–4V, the fatigue response is also influenced by inherent defects of as-built parts. Regarding the recently developed metastable β alloys, information about the fatigue properties is still scarce and mainly related to the effect of second phase precipitates, which are introduced to optimize the mechanical properties. The fatigue behavior of the Ti alloys is complex, as is their microstructure, and should not be neglected when the alloys are being developed or improved to be applied in medical devices.
Journal Article