In the paper, a novel magneto-electro-elastic model of bi-directional (2D) functionally graded materials (FGMs) beams is developed for investigating the nonlinear dynamics. It is shown that the ...asymmetric modes induced by the 2D FGMs may significantly affect the nonlinear dynamic responses, which is tremendously different from previous studies. Taking into account the geometric nonlinearity, the nonlinear equation of motion and associated boundary conditions for the beams are derived according to the Hamilton’s principle. The natural frequencies and numerical modes of the beams are calculated by the generalized differential quadrature method. The frequency responses of the nonlinear forced vibration are constructed based on the Galerkin technique incorporating with the incremental harmonic balance approach. The influences of the material distributions, length–thickness ratio, electric voltage, magnetic potential as well as boundary condition on the nonlinear resonant frequency and response amplitude are discussed in details. It is notable that increasing in the axial and thickness FG indexes, negative electric potential and positive magnetic potential can lead to decline the nonlinear resonance frequency and amplitude peak, which is usually applied to accurately design the multi-ferroic composite structures. Furthermore, the nonlinear characteristics of motion can be regulated by tuning/tailoring the 2D FG materials.
Microbial infections affect humans worldwide. Many quaternary ammonium compounds have been synthesized that are not only antibacterial, but also possess antifungal, antiviral and anti-matrix ...metalloproteinase capabilities. Incorporation of quaternary ammonium moieties into polymers represents one of the most promising strategies for preparation of antimicrobial biomaterials. Various polymerization techniques have been employed to prepare antimicrobial surfaces with quaternary ammonium functionalities; in particular, syntheses involving controlled radical polymerization techniques enable precise control over macromolecular structure, order and functionality. Although recent publications report exciting advances in the biomedical field, some of these technological developments have also been accompanied by potential toxicological and antimicrobial resistance challenges. Recent evidenced-based data on the biomedical applications of antimicrobial quaternary ammonium-containing biomaterials that are based on randomized human clinical trials, the golden standard in contemporary medicinal science, are included in the present review. This should help increase visibility, stimulate debates and spur conversations within a wider scientific community on the implications and plausibility for future developments of quaternary ammonium-based antimicrobial biomaterials.
Flexible and sensitive sensors that can detect external stimuli such as pressure, temperature, and strain are essential components for applications in health diagnosis and artificial intelligence. ...Multifunctional sensors with the capabilities of sensing pressure and temperature simultaneously are highly desirable for health monitoring. Here, we have successfully fabricated a flexible and simply structured bimodal sensor based on metal–organic frameworks (MOFs) derived porous carbon (PC) and polydimethylsiloxane (PDMS) composite. Attributed to the porous structure of PC/PDMS composite, the fabricated sensor exhibits high sensitivity (15.63 kPa–1), fast response time (<65 ms), and high durability (∼2000 cycles) for pressure sensing. Additionally, its application in detecting human motions such as subtle wrist pulses in real time has been demonstrated. Furthermore, the as-prepared device based on the PC/PDMS composite exhibits a good sensitivity (>0.11 °C–1) and fast response time (∼100 ms), indicating its potential application in sensing temperature. All of these capabilities indicate its great potential in the applications of health monitoring and artificial skin for artificial intelligence system.
Mitochondrial fission and selective mitochondrial autophagy (mitophagy) form an essential axis of mitochondrial quality control that plays a critical role in the development of cardiac ...ischemia-reperfusion (IR) injury. However, the precise upstream molecular mechanism of fission/mitophagy remains unclear. Dual-specificity protein phosphatase1 (DUSP1) regulates cardiac metabolism, but its physiological contribution in the reperfused heart, particularly its influence on mitochondrial homeostasis, is unknown. Here, we demonstrated that cardiac DUSP1 was downregulated following acute cardiac IR injury. In vivo, compared to wild-type mice, DUSP1 transgenic mice (DUSP1TG mice) demonstrated a smaller infarcted area and the improved myocardial function. In vitro, the IR-induced DUSP1 deficiency promoted the activation of JNK which upregulated the expression of the mitochondrial fission factor (Mff). A higher expression level of Mff was associated with elevated mitochondrial fission and mitochondrial apoptosis. Additionally, the loss of DUSP1 also amplified the Bnip3 phosphorylated activation via JNK, leading to the activation of mitophagy. Increased mitophagy overtly consumed mitochondrial mass resulting into the mitochondrial metabolism disorder. However, the reintroduction of DUSP1 blunted Mff/Bnip3 activation and therefore alleviated the fatal mitochondrial fission/mitophagy by inactivating the JNK pathway, providing a survival advantage to myocardial tissue following IR stress. The results of our study suggest that DUSP1 and its downstream JNK pathway are therapeutic targets for conferring protection against IR injury by repressing Mff-mediated mitochondrial fission and Bnip3-required mitophagy.
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•IR injury induces DUSP1 downregulation.•Loss of DUSP1 leads to an increase in JNK phosphorylation.•JNK activates Mff and Bnip3, contributing to the fatal mitochondrial fission and mitophagy, respectively.•Fission and mitophagy induces cell damage via trigging caspase9-related apoptosis and mitochondrial energy disorder.
Co-speech gestures are closely connected to speech, but little attention has been paid to the associations between gesture and L2 speech performance. This study explored the associations between four ...types of co-speech gestures (namely, iconics, metaphorics, deictics, and beats) and the meaning, form, and discourse dimensions of L2 speech performance. Gesture and speech data were collected by asking 61 lower-intermediate English learners whose first language is Chinese to retell a cartoon clip. Results showed that all the four types of co-speech gestures had positive associations with meaning and discourse L2 speech measures but no association with form-related speech measures, except the positive association between metaphorics and the percentage of error-free clauses. The findings suggest that co-speech gestures may have a tighter connection with meaning construction in producing L2 speech.
Visual odometry (VO) is a prevalent way to deal with the relative localization problem, which is becoming increasingly mature and accurate, but it tends to be fragile under challenging environments. ...Comparing with classical geometry-based methods, deep-learning-based methods can automatically learn effective and robust representations, such as depth, optical flow, feature, ego-motion, etc., from data without explicit computation. Nevertheless, there still lacks a thorough review of the recent advances of deep-learning-based VO (Deep VO). Therefore, this article aims to gain a deep insight on how deep learning can profit and optimize the VO systems. We first screen out a number of qualifications, including accuracy, efficiency, scalability, dynamicity, practicability, and extensibility, and employ them as the criteria. Then, using the offered criteria as the uniform measurements, we detailedly evaluate and discuss how deep learning improves the performance of VO from the aspects of depth estimation, feature extraction and matching, and pose estimation. We also summarize the complicated and emerging areas of Deep VO, such as mobile robots, medical robots, augmented and virtual reality, etc. Through the literature decomposition, analysis, and comparison, we finally put forward a number of open issues and raise some future research directions in this field.
Despite the increasingly important role of Hippo-Yap in hepatocellular carcinoma (HCC) development and progression, little insight is available at the time regarding the specifics interaction of Yap ...and cancer cells migration. Here, we identified the mechanism by which tumor-intrinsic Yap deletion resulted in HCC migratory inhibition. Yap was greatly upregulated in HCC and its expression promoted the cells migration. Functional studies found that knockdown of Yap induced JNK phosphorylation which closely bound to the Bnip3 promoter and contributed to Bnip3 expression. Higher Bnip3 employed excessive mitophagy leading to mitochondrial dysfunction and ATP shortage. The insufficient ATP inactivated SERCA and consequently triggered intracellular calcium overload. As the consequence of calcium oscillation, Ca/calmodulin-dependent protein kinases II (CaMKII) was signaled and subsequently inhibited cofilin activity via phosphorylated modification. The phosphorylated cofilin failed to manipulate F-actin polymerization and lamellipodium formation, resulting into the impairment of lamellipodium-based migration. Collectively, our results identified Hippo-Yap as the tumor promoter in hepatocellular carcinoma that mediated via activation of cofilin/F-actin/lamellipodium axis by limiting JNK-Bnip3-SERCA-CaMKII pathways, with potential application to HCC therapy involving cancer metastasis.
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•Yap is upregulated in the hepatocellular carcinoma and promotes cancer cell migration.•Loss of Yap impairs cell mobility via inhibiting cofilin/F-actin/lamellipodium by activation of JNK-Bnip3-SERCA-CaMKII.•Loss of Yap enhances JNK phosphorylation which triggers Bnip3-required mitophagy.•Excessive mitophagy induces mitochondrial energy disorder which blunts SERCA and causes calcium overload.•The calcium overload drives CaMKII which inactivates cofilin, leading to F-actin degradation and lamellipodium collapse.
Depression is closely linked to an imbalance in the autonomic nervous system (ANS). However, the role of this imbalance in mediating the effects of sleep deprivation (SD) and vagus nerve stimulation ...(VNS) on emotional well-being is not fully understood.
A population-based analysis was conducted to explore the relationship between sleep duration, depression scores, and heart rate variability (HRV). Additionally, the chronic SD mouse model was established to assess the impact of preventive transcutaneous auricular VNS (taVNS) on pathological and behavioral changes.
Our study found a significant link between sleep duration, depression severity, and HRV. Shorter sleep duration was associated with higher depression scores and lower RMSSD (a measure of HRV). In our rat model, insufficient sleep consistently impaired HRV. This effect was mitigated by taVNS, accompanied by corresponding changes in levels of IL-1β and IL-6, astrocyte and microglia activation, and tail suspension times.
Using VNS as a preventive treatment for depression-risk individuals with insufficient sleep shows promise. It not only broadens the potential applications of VNS but also sheds light on its mechanism—particularly its role in enhancing vagal nerve function and balancing the ANS, as evidenced by HRV measurements.
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•The imbalance of the autonomic nervous system (ANS) caused by sleep deprivation (SD) mediates the occurrence of depression.•Transcutaneous auricular vagus nerve stimulation (taVNS), by ameliorating ANS, reduces SD-induced depression preventively.•The potential benefits of taVNS can be quantified using heart rate variability, which endows it with new application values.
Empirical and anecdotal evidence has associated stress with accelerated hair greying (formation of unpigmented hairs)
, but so far there has been little scientific validation of this link. Here we ...report that, in mice, acute stress leads to hair greying through the fast depletion of melanocyte stem cells. Using a combination of adrenalectomy, denervation, chemogenetics
, cell ablation and knockout of the adrenergic receptor specifically in melanocyte stem cells, we find that the stress-induced loss of melanocyte stem cells is independent of immune attack or adrenal stress hormones. Instead, hair greying results from activation of the sympathetic nerves that innervate the melanocyte stem-cell niche. Under conditions of stress, the activation of these sympathetic nerves leads to burst release of the neurotransmitter noradrenaline (also known as norepinephrine). This causes quiescent melanocyte stem cells to proliferate rapidly, and is followed by their differentiation, migration and permanent depletion from the niche. Transient suppression of the proliferation of melanocyte stem cells prevents stress-induced hair greying. Our study demonstrates that neuronal activity that is induced by acute stress can drive a rapid and permanent loss of somatic stem cells, and illustrates an example in which the maintenance of somatic stem cells is directly influenced by the overall physiological state of the organism.
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