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BackgroundAutism spectrum disorder (ASD) is a complex neurodevelopmental disorder with an unknown etiology. Early diagnosis and intervention are key to improving outcomes for patients with ASD. Structural magnetic resonance imaging (sMRI) has been widely used in clinics to facilitate the diagnosis of brain diseases such as brain tumors. However, sMRI is less frequently used to investigate neurological and psychiatric disorders, such as ASD, owing to the subtle, if any, anatomical changes of the brain. ObjectiveThis study aimed to investigate the possibility of identifying structural patterns in the brain of patients with ASD as potential biomarkers in the diagnosis and evaluation of ASD in clinics. MethodsWe developed a novel 2-level histogram-based morphometry (HBM) classification framework in which an algorithm based on a 3D version of the histogram of oriented gradients (HOG) was used to extract features from sMRI data. We applied this framework to distinguish patients with ASD from healthy controls using 4 datasets from the second edition of the Autism Brain Imaging Data Exchange, including the ETH Zürich (ETH), NYU Langone Medical Center: Sample 1, Oregon Health and Science University, and Stanford University (SU) sites. We used a stratified 10-fold cross-validation method to evaluate the model performance, and we applied the Naive Bayes approach to identify the predictive ASD-related brain regions based on classification contributions of each HOG feature. ResultsOn the basis of the 3D HOG feature extraction method, our proposed HBM framework achieved an area under the curve (AUC) of >0.75 in each dataset, with the highest AUC of 0.849 in the ETH site. We compared the 3D HOG algorithm with the original 2D HOG algorithm, which showed an accuracy improvement of >4% in each dataset, with the highest improvement of 14% (6/42) in the SU site. A comparison of the 3D HOG algorithm with the scale-invariant feature transform algorithm showed an AUC improvement of >18% in each dataset. Furthermore, we identified ASD-related brain regions based on the sMRI images. Some of these regions (eg, frontal gyrus, temporal gyrus, cingulate gyrus, postcentral gyrus, precuneus, caudate, and hippocampus) are known to be implicated in ASD in prior neuroimaging literature. We also identified less well-known regions that may play unrecognized roles in ASD and be worth further investigation. ConclusionsOur research suggested that it is possible to identify neuroimaging biomarkers that can distinguish patients with ASD from healthy controls based on the more cost-effective sMRI images of the brain. We also demonstrated the potential of applying data-driven artificial intelligence technology in the clinical setting of neurological and psychiatric disorders, which usually harbor subtle anatomical changes in the brain that are often invisible to the human eye.

Traditional heat conductive epoxy composites often fall short in meeting the escalating heat dissipation demands of large‐power, high‐frequency, and high‐voltage insulating packaging applications, due to the challenge of achieving high thermal conductivity (k), desirable dielectric performance, and robust thermomechanical properties simultaneously. Liquid crystal epoxy (LCE) emerges as a unique epoxy, exhibiting inherently high k achieved through the self‐assembly of mesogenic units into ordered structures. This characteristic enables liquid crystal epoxy to retain all the beneficial physical properties of pristine epoxy, while demonstrating a prominently enhanced k. As such, liquid crystal epoxy materials represent a promising solution for thermal management, with potential to tackle the critical issues and technical bottlenecks impeding the increasing miniaturization of microelectronic devices and electrical equipment. This article provides a comprehensive review on recent advances in liquid crystal epoxy, emphasizing the correlation between liquid crystal epoxy's microscopic arrangement, organized mesoscopic domain, k, and relevant physical properties. The impacts of LC units and curing agents on the development of ordered structure are discussed, alongside the consequent effects on the k, dielectric, thermal, and other properties. External processing factors such as temperature and pressure and their influence on the formation and organization of structured domains are also evaluated. Finally, potential applications that could benefit from the emergence of liquid crystal epoxy are reviewed. [ABSTRACT FROM AUTHOR]

Polymers with high thermal conductivity (TC) and dielectric constant (ε) but low dielectric loss show enormously potential applications in electrical power systems. To enhance the ε and TC while significantly suppressing the loss of β‐silicon carbide whisker (β‐SiCw)/polyvinylidene fluoride (PVDF), in this study, SiO2 shells with different morphologies were constructed on the superficies of β‐SiCw via a facile oxidation method in air atmosphere. The SiO2 shell' morphology on the TC and dielectric performances of the β‐SiCw@SiO2/PVDF are systematically explored as a function of the frequency and filler loading. The β‐SiCw@SiO2/PVDF demonstrate astonishingly restricted loss and meliorative TC when compared to the β‐SiCw/PVDF because the SiO2 shell not only suppresses the β‐SiCw from direct contact with one another and impedes the long‐distance charges migration thereby resulting in rather low loss and leakage conductivity, but also restrains the thermal interfacial resistance via increased interfacial compatibility and interactions. The concurrent enhancement effect in the ε and TC but low loss of the composites is more evident in the crystalline SiO2 interlayer with a high TC compared with amorphous one. These results provide insight into the exploration of composite nanodielectrics with large TC and ε but low loss for applications in electrical power systems. Highlights: Core@shell structured β‐SiCw@SiO2/PVDF were obtained by a facile oxidation.The great reduction in both loss and conductivity is attributed to the SiO2 shell.Crystalline SiO2 shell can improve the composites' thermal conductivity.The SiO2 shell prevents long‐range carrier migration. [ABSTRACT FROM AUTHOR]

As the electronic industry develops rapidly, nowadays, flexible dielectric materials with excellent integrated dielectric performances including high dielectric permittivity (ɛ) and breakdown strength (Eb) but low loss, are highly pursued. In this work, to concurrently improve the ɛ and Eb but restrain the loss of original Si/polyvinylidene fluoride (PVDF) composites, the core@shell structured Si@SiO2 particles first were produced via high temperature oxidation process, and then incorporated into the PVDF to generate morphology-dependent composites with high-ɛ and Eb but low loss. The dielectric properties of the composites were investigated in terms of the filler types and concentrations, frequency, and theoretically fitted using the Havriliak-Negami equation to reveal the SiO2 shell' role in affecting the polarization mechanism. When compared to pure Si/PVDF at high filler loadings, remarkably inhibited dielectric loss and conductivity as well as enhanced Eb concurrently can be achieved in the Si@SiO2/PVDF composites still harvesting a high-ɛ. This is because the insulating SiO2 shell not only effectively prevents the raw Si particles from direct physical contact, but also greatly impedes the long-range charge carrier migration via raising energy barrier subsequently leading to obviously enhanced Eb. Moreover, the dielectric loss and conductivity apparently decrease with increasing the SiO2 shell thickness due to its pronounced suppression effect. The prepared Si@SiO2/PVDF with a high Eb and ɛ but low loss, show bright future uses in micro-electronic devices used for high-voltage purposes. [ABSTRACT FROM AUTHOR]

Polymer composites with high dielectric permittivity (ε´) and breakdown strength (Eb), low loss, have significant applications in electronics device and electrical equipment. To harvest excellent integrated dielectric properties in molybdenum (Mo)/polyvinylidene fluoride (PVDF), in this study, raw Mo particles were calcined at high temperature to obtain molybdenum oxide (MoO3), followed by the encapsulation of a layer of polystyrene (PS) shell, and the fabricated core@double-shell structured Mo (Mo@MoO3@PS) particles were incorporated into PVDF. The measurement outcomes demonstrate the coexistence of the MoO3 and PS double shells on the surface of raw Mo particle. The first inorganic MoO3 interlayer massively suppresses the dielectric loss and leakage current of Mo/PVDF because it effectively prevents the direct contact between raw Mo particles. The second organic PS shell not only greatly strengthens the interfacial compatibility with PVDF thereby enhancing the fillers' homogeneous dispersibility in the matrix, but also further suppresses the conductivity and loss, and improves the Eb of the composites owing to its high electrical resistivity. The PVDF with 40 wt% of Mo@MoO3@PS exhibits good comprehensive dielectric performances: ε′ of 100 and Eb of 7.89 kV/mm, loss factor of 0.058 at 100 Hz. Consequently, the obtained Mo@MoO3@PS/PVDF with concurrently high-ε′ and Eb but low loss shows promising potential applications in microelectronics and electrical industries. [ABSTRACT FROM AUTHOR]

An insulating shell on the surface of conductive particles is vital for restraining the dielectric loss and leakage current of polymer composites. So as to inhibit the enormous loss and conductivity of pristine nickel (Ni)/poly(vinylidene fluoride)(PVDF) composites but still harvest a high dielectric permittivity (εr) when filler loading approaches or exceeds the percolation threshold (fc), pristine Ni particles were covered by a layer of titanium dioxide (TiO2) shell via a sol–gel approach, and then they were composited with PVDF. The impacts of the TiO2 coating on the dielectric performances of the Ni/PVDF composites were explored as a function of the filler concentration, the shell thickness and frequency. In addition, the dielectric performances were fitted using the Havriliak–Negami (H–N) equation in order to further understand the TiO2 shell's effect on polarization mechanism in the composites. The Ni@TiO2/PVDF composites exhibit high εr and enhanced breakdown strength (Eb) but remarkably suppressed loss and conductivity when compared with pristine Ni/PVDF because the TiO2 shell can efficiently stop the direct contact between Ni particles thereby suppressing the long–range electron transportation. Further, the dielectric performances can be effectively tuned through finely adjusting the TiO2 shell' thickness. The resulting Ni@TiO2/PVDF composites with high εr and Eb but low loss show appealing applications in microelectronics and electrical fields. [ABSTRACT FROM AUTHOR]