Resting-state fMRI is a novel approach to measure spontaneous brain activity in patients with major depressive disorder (MDD). Although most resting-state fMRI studies have focused on the examination ...of temporal correlations between low-frequency oscillations (LFOs), few studies have explored the amplitude of these LFOs in MDD. In this study, we applied the approaches of amplitude of low-frequency fluctuation (ALFF) and fractional ALFF to examine the amplitude of LFOs in MDD.
A total of 36 subjects, 18 first-episode, treatment-naive patients with MDD matched with 18 healthy controls (HCs) completed the fMRI scans. Compared with HCs, MDD patients showed increased ALFF in the right fusiform gyrus and the right anterior and posterior lobes of the cerebellum but decreased ALFF in the left inferior temporal gyrus, bilateral inferior parietal lobule, and right lingual gyrus. The fALFF in patients was significantly increased in the right precentral gyrus, right inferior temporal gyrus, bilateral fusiform gyrus, and bilateral anterior and posterior lobes of the cerebellum but was decreased in the left dorsolateral prefrontal cortex, bilateral medial orbitofrontal cortex, bilateral middle temporal gyrus, left inferior temporal gyrus, and right inferior parietal lobule. After taking gray matter (GM) volume as a covariate, the results still remained.
These findings indicate that MDD patients have altered LFO amplitude in a number of regions distributed over the frontal, temporal, parietal, and occipital cortices and the cerebellum. These aberrant regions may be related to the disturbances of multiple emotion- and cognition-related networks observed in MDD and the apparent heterogeneity in depressive symptom domains. Such brain functional alteration of MDD may contribute to further understanding of MDD-related network imbalances demonstrated in previous fMRI studies.
•Distant spatial profiles were observed in the low amplitudes of the slow-4 versus slow-5 frequency bands derived from resting-state fMRI signals.•MDD patients showed altered ALFF and fALFF in widely ...distributed brain regions.•The alteration in ALFF and fALFF in MDD patients were dependent on the choice of different frequency bands.
We conducted this fMRI study to examine whether the alterations in amplitudes of low-frequency oscillation (LFO) of major depressive disorder (MDD) patients were frequency dependent.
The LFO amplitudes (as indexed by amplitude of low-frequency fluctuation ALFF and fractional ALFF fALFF) within 4 narrowly-defined frequency bands (slow-5: 0.01–0.027Hz, slow-4: 0.027–0.073Hz, slow-3: 0.073–0.198Hz, and slow-2: 0.198–0.25Hz) were computed using resting-state fMRI data of 35 MDD patients and 32 healthy subjects. Repeated-measures analysis of variance (ANOVA) was performed on ALFF and fALFF both within the low frequency bands of slow-4 and slow-5 and within all of the four bands.
We observed significant main effects of group and frequency on ALFF and fALFF in widely distributed brain regions. Importantly, significant group and frequency interaction effects were observed in the ventromedial prefrontal cortex, inferior frontal gyrus, precentral gyrus, in a left-sided fashion, the bilateral posterior cingulate and precuneus, during ANOVA both within slow-4 and slow-5 bands and within all the frequency bands.
The results suggest that the alterations of LFO amplitudes in specific brain regions in MDD patients could be more sensitively detected in the slow-5 rather than the slow-4 bands. The findings may provide guidance for the frequency choice of future resting-state fMRI studies of MDD.
Tiny machine learning (TinyML) aims to bring machine learning to the extreme edge, i.e., the microcontroller next to the sensor, which is expected to unlock new smart applications and pave the way ...for the last mile of artificial intelligence. Meanwhile, gesture recognition, as an important technology for realizing human-computer interaction (HCI), is of great significance for enabling convenient interaction between people and smart devices. Currently, the more mature static hand gesture recognition solutions include the use of data gloves or vision cameras to capture static hand gestures, which have many limitations in practical applications, such as cumbersome wearing process and performance affected by lighting conditions, and the processing platform mostly relies on cloud or edge servers. Considering the above limitations, in this paper, we design and implement a static hand gesture recognition system based on an ultra-low resolution infrared array sensor and a low-cost AI chip from the perspective of tiny machine learning applications. On the one hand, a fast method of collecting and labeling sensor data is introduced, and on the other hand, an ultra-lightweight neural network model is customized for the low-cost AI chip. The experimental results show that the static hand gesture recognition system designed and implemented in this paper has 99.14% recognition accuracy for several simple static hand gestures, and its inference time at the microcontroller side is around 35ms, which can achieve accurate and real-time recognition with low cost, strong anti-interference capability and good privacy.
Here we report a highly scalable yet flexible triple-layer structured porous C/SiO2 membrane via a facile phase inversion method for advancing Li–sulfur battery technology. As a multifunctional ...current-collector-free cathode, the conductive dense layer of the C/SiO2 membrane offers hierarchical macropores as an ideal sulfur host to alleviate the volume expansion of sulfur species and facilitate ion/electrolyte transport for fast kinetics, as well as spongelike pores to enable high sulfur loading. The triple-layer structured membrane cathode enables the filling of most sulfur species in the macropores and additional loading of a thin sulfur slurry on the membrane surface, which facilitates ion/electrolyte transport with faster kinetics than the conventional S/C slurry-based cathode. Furthermore, density functional theory simulations and visual adsorption measurements confirm the critical role of the doped SiO2 nanoparticles (∼10 nm) in the asymmetric C membrane in suppressing the shuttle effect of polysulfides via chemisorption and electrocatalysis. The rationally designed C/SiO2 membrane cathodes demonstrate long-term cycling stability of 300 cycles at a high sulfur loading of 2.8 mg cm–2 with a sulfur content of ∼75%. This scalable yet flexible self-supporting cathode design presents a useful strategy for realizing practical applications of high-performance Li–S batteries.
With the rapid growth of material innovations, multishelled hollow nanostructures are of tremendous interest due to their unique structural features and attractive physicochemical properties. ...Continued effort has been made in the geometric manipulation, composition complexity, and construction diversity of this material, expanding its applications. Energy storage technology has benefited from the large surface area, short transport path, and excellent buffering ability of the nanostructures. In this work, the general synthesis of multishelled hollow structures, especially with architecture versatility, is summarized. A wealth of attractive properties is also discussed for a wide area of potential applications based on energy storage systems, including Li‐ion/Na‐ion batteries, supercapacitors, and Li–S batteries. Finally, the emerging challenges and outlook for multishelled hollow structures are mentioned.
Numerous unique properties and functionalities have prompted the design and engineering of multishelled transition metal‐based microspheres. Here, a detailed overview of the various synthetic strategies is given including hard‐templating, soft‐templating, and free‐template methods, and insight is offered into the great promise for energy storage systems in the application of lithium/sodium batteries, supercapacitors, and lithium‐surfer batteries.
•Size-tunable ZIF-8 nanoparticles were distributed uniformly in Pebax without obvious defects.•ZIF-8 nanoparticles with different sizes were obtained in microemulsion by controlling the ratio of Zn2+ ...to Hmim.•Both CO2 permeability and CO2/N2 selectivity are improved significantly by incorporation of ZIF-8.
Poly (ether-block-amide) (Pebax) based mixed matrix membranes (MMMs) were prepared by using size-tunable ZIF-8 nanoparticles as fillers. ZIF-8 nanoparticles with sizes of 40, 60, 90 and 110 nm (ZIF-8-40, ZIF-8-60, ZIF-8-90 and ZIF-8-110) were synthesized in microemulsion by controlling the ratio of Zn2+ to Hmim (1:16, 1:8, 1:5, 1:2). And they were distributed uniformly in Pebax matrix without obvious agglomerations and defects at the loading of 0–20 wt.%, which was confirmed by field-emission scanning electron microscopy (FE-SEM). The incorporation of ZIF-8 resulted in a significant improvement in CO2 permeability and the CO2/N2 selectivity increased with the BET surface area of ZIF-8 increasing. The enhanced permeability is attributed to an improvement in the free volume of the polymer induced by larger sized ZIF-8, while the increased selectivity results from the high specific surface area of large sized ZIF-8, which can provide more active sites for CO2 capture and great mass transfer resistance for N2. At 5 wt.% loading of ZIF-8-90, the MMM presents the best separation performance with CO2 permeability of 99.7 Barrer and CO2/N2 selectivity of 59.6, both of which are increased by about 25% by comparison to the pure Pebax membrane. The present study provides an effective way to obtain size-controlled ZIF-8 fillers and high separation performances of Pebax based MMMs.
Carbon nanotubes (CNTs) with 1D gas transport channel has great prospect in MMMs based CO2 separation. However, the insufficient compatibility with polymer and inner diameter of CNTs limit further ...improvement of their CO2 separation performances. In this work, the unique ZIF-8 hollow nanotubes (HNTs) were proposed to construct high-speed gas transmission channel in MMMs by a three-step method (electrospinning-calcination-hydrothermal), aiming at concurrently improving the gas permeability and selectivity. The hollow inner cavity provides long-range and low-resistance gas transmission channels to ensure high gas permeability. At the same time, the ZIF-8 crystals composing the tube wall can not only screen for gas molecules pair, but also strengthen the affinity between the filler and polymer matrix by its organic ligands, thus the gas selectivity can be raised. Compared with ZIF-8 nanoparticles and ZnO HNTs, ZIF-8 HNTs based MMMs present competitive CO2 separation. When the loading of ZIF-8 HNTs is 5 wt%, the gas separation performance shows the best, in which the CO2 permeability is 147 Barrer and the CO2/N2 selectivity is 68, approaching to the 2008 Robeson upper limit and surpassing most reported CNTs/Pebax based membranes. Therefore, the proposed ZIF-8 HNTs are promising for MMMs based CO2 separation.
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•ZIF-8 HNTs were designed by three steps of electrospinning-calcination- hydrothermal.•ZIF-8 HNTs were proposed to construct high-speed gas transmission channel in MMMs.•CO2 permeability of ZIF-8 HNTs MMMs is 147 Barrer, 63% higher than that of pure ZIF-8.•CO2/N2 selectivity of ZIF-8 HNTs MMMs is 68, 15% higher than that of pure ZIF-8.•CO2 permeability and selectivity of ZIF-8 HNTs/Pebax surpassed most reported CNTs/Pebax.
•Amino groups are introduced into ZIF-8 by microemulsion based mixed linker strategy.•Mixed linker strategy presents a less reduction in SBET of ZIF-8 than post synthetic modification.•NH2-ZIF-8 show ...improved interfacial compatibility with Pebax.•NH2-ZIF-8/Pebax MMMs show a simultaneous increase in CO2 permeability and CO2/N2 selectivity.
High permeability and selectivity are desirable for mixed matrix membranes (MMMs) based CO2 separation. Herein, a microemulsion based mixed linker strategy is proposed to introduce amino groups during the growth of ZIF-8. Compared to post-synthetic modification, this method presents a less reduction in SBET of ZIF-8, which is beneficial for CO2 adsorption. By controlling the ratio of 2-methylimidazole to 2-aminobenzimidazole, NH2-ZIF-8 with various morphologies and sizes were synthesized and serve as the filler to fabricate the MMMs for CO2 capture. From the scanning electron microscopy (SEM), no obvious agglomerations or defects are observed in ZIF-8/Pebax MMMs, due to the amino groups in ZIF-8 can interact with the amide in Pebax chain, which can improve compatibility between ZIF-8 and Pebax. With the amino groups, NH2-ZIF-8 shows higher affinity with CO2 than that of non-amine-functionalized ZIF-8, leading to an enhancement in the separation performances. When the MMM doped with 6 wt% of NH2-ZIF-8(10), the CO2 permeability reaches up to 163.8 Barrer, which increases by around 53% and 107.6% in contrast with the ZIF-8/Pebax MMM and pure Pebax membrane. Besides, the CO2/N2 selectivity is enhanced by around 10% and 27%, respectively. These results indicate that amine-functional modification by mixed ligands is a useful way to construct MOFs-based MMMs with high performance for CO2/N2 separation.
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