•The reinforced hat-shaped specimens are designed to study the dynamic shear mechanical properties of ice.•The dynamic shear mechanical properties of the ice are tested at strain rates ranging from ...17,000 /s to 61,000 /s.•The relationship between dynamic shear strengths and shear strain rates is linear.•The shear strain-rate sensitivities of ice on the internal friction angle and cohesion of the Mohr-Coulomb criterion are different.
The failure of ice is dominated by shear failure mode at certain specific stress states. The dynamic shear mechanical properties of ice are investigated using reinforced hat-shaped specimens and SHPB experiments at shear strain rates ranging from 17,000 /s to 61,000 /s. The experimental results show that the mechanical properties of ice on dynamic shear are sensitive to shear strain rate. And the relationship between dynamic shear strengths and shear strain rates is linear. The Mohr-Coulomb criterion is employed to determine the failure of ice at complex stress states. The internal friction angle of the Mohr-Coulomb criterion for ice is a constant (34.31°) which is insensitive to the shear strain rate, but the cohesion of the Mohr-Coulomb criterion for ice is sensitive to the shear strain rate. These results could provide experimental technique and theoretical basis for improving the dynamic constitutive model of ice to describe the integrated failure mode of ice with complex stress states accurately.
Chronic stress and lack of reward may reduce the function of the brain’s reward circuits, leading to major depressive disorder. The effect of reward treatment on chronic stress-induced ...depression-like behaviors and its molecular mechanism in the brain remain unclear. In this study, companion communication was used as a reward to study the effect of reward on CUMS-induced depression-like behaviors, and mRNA and miRNA profiles in the medial prefrontal cortex harvested from mice with depression-like and resilient behaviors were established by high-throughput sequencing. The results showed that accompanying with companion ameliorated CUMS-induced depression-like behaviors in mice. Furthermore, 45 differentially expressed genes (DEGs) associated with depression-like behaviors, 8 DEGs associated with resilience and 59 DEGs associated with nature reward (companion) were identified, and 196 differentially expressed miRNAs were found to be associated with companion. Based on the differentially expressed miRNAs and DEGs data, miRNA-mRNA network was established to be associated with companion. Taken together, our data here provided a method to ameliorate depression-like behaviors, and numerous potential drug targets for the prevention or treatment of depression.
•Chronic unpredictable mild stress to mice leads to either depression-like behaviors or resilience.•Accompanied with confidant (reward treatment) ameliorated CUMS-induced depression-like behaviors in mice.•Bioinformatics analysis of transcriptome sequencing screened out genes related to depression, resilience and reward.
Numerical simulations of WIV (wake induced vibration) for tandem cylinders with different diameter ratio in the impingement regime are performed for a low Reynolds number of Re = 150 and low mass ...ratio of m* = 2.0. Five different diameter ratios of d/D = 1/2, 3/4, 1, 4/3, and 3/2 are examined, in order to identify the effects of diameter ratio on 2-DOF (two-degree-of-freedom) vibration responses of the cylinder in the range of 2≤Ur ≤ 14. The results show that the diameter ratio and vortex mode play important roles in the vibration amplitudes and frequencies of the downstream cylinder. The WIV can be further classified into WIEV (wake interference and enhancement vibration) and WCV (wake controlled vibration) according to two distinct mechanisms of the amplification of cross-flow vibration amplitude. As d/D ≤ 1, the vibration frequencies of the downstream cylinder are significantly pulled down and interfered by the small vortices shedding from the small upstream cylinder. Meanwhile, a wider range of lock-in and enhanced vibration amplitudes are the features for WIEV. The inline direction of the downstream cylinder have large response amplitudes in a wide range of Ur (reduced velocity) and reach to the maximum value at d/D = 1. As d/D > 1, the hydrodynamic characteristics of the downstream cylinder are mainly controlled by the larger vortices shedding from the upstream cylinder. The downstream cylinder vibrates as the vortex shedding frequency of the larger upstream cylinder and the lock-in phenomenon is absent. WCV significantly increases the risk of fatigue failure of the cylindrical structure.
•WIV of different diameter ratios and distinct vortex modes is numerically studied.•WIV is further classified into WIEV and WCV.•WCV is attached with large amplitude and high frequency.•Inline vibration cannot be ignored for WIV.•Incoming vortex feature and mode dominates the characteristic of WIV.
Triboelectric-electromagnetic hybrid nanogenerator (HNG) exhibits exceptional output performance, rendering it a highly viable solution for powering tiny electronics in the foreseeable future. ...However, the construction of a simple structure and light weight HNG using magnetizable triboelectric materials is a highly desirable yet challenging task. Herein, we present a HNG based on flexible neodymium iron boron/polyvinyl chloride (Nd2Fe14B/PVC) composite films for efficiently harvesting mechanical energy from the environment. By embedding Nd2Fe14B powder in PVC matrix, the as-prepared Nd2Fe14B/PVC composites possess desirable triboelectricity and magnetic strength, which is advantageous in replacing traditional heavy magnets to construct a lightweight HNG with high performance. Under a force of 3.8 N and a frequency of 2.1 Hz, the triboelectric nanogenerator (TENG) produces an output power of 4.5 mW at a loading resistance of 5 MΩ, while the electromagnetic generator (EMG) generates up to 0.11 mW at a loading resistance of 200 Ω. The HNG exhibits superior stability and better charging performance compared to single energy harvesting units. A commercial 470 μF capacitor can be charged to 3 V within 385 s through the HNG, which can continuously supply electrical energy to a hygrothermograph and vernier scale. This work provides an effective method for preparing magnetizable triboelectric materials and introduces new possibilities for the rational design of simple structure and lightweight HNGs.
A light-weight and stable hybridized triboelectric-electromagnetic nanogenerator with high-performance is designed based on flexible neodymium iron boron/polyvinyl chloride (Nd2Fe14B/PVC) composite film, which can continuously provide electrical energy for a hygrothermograph and vernier scale. Display omitted
•Design a simple and lightweight hybridized triboelectric-electromagnetic nanogenerator remains a challenge.•The novel magnetizable triboelectric film exhibits desirable triboelectricity and magnetic strength.•A hybridized nanogenerator is constructed based on flexible magnetizable Nd2Fe14B/PVC film.•The hybridized nanogenerator can continuously power a hygrothermograph and vernier scale.•This work provides an effective method for preparing magnetizable triboelectric materials.
•The efficacy of VIV suppression is excellent while the attack is larger than the critical angle.•Phase closely relates to the reduction of transverse displacement amplitude of the circular cylinder ...with 3 control rods.•Two symmetrical configurations (α=0º and α=60º) result in totally different symmetrical vibration trajectories.•The frequencies of vibration of the main cylinder with 3 control rods are generally smaller than that of an isolated cylinder.•2 rods in behind of the main cylinder perform more efficient than that of 1 rod in front for VIV suppression as the gap ratio of G/D less than 1.0.
Laminar flow past a circular cylinder with 3 small control rods is investigated by numerical simulation. This study is concerned with the suppression efficacy of vortex induced vibration by small control rods located around a main cylinder. The effects of the attack angle and rod-to-cylinder gap ratio on the hydrodynamics and vibration responses of the main cylinder are investigated. The attack angle of α=45° is performed as the critical angle for VIV suppression of 3 control rods. The 3 control rods have no effect on VIV suppression when the attack angle is less than the critical angle. The 3 control rods have an excellent VIV suppression efficacy when the attack angle is larger than the critical angle. The transverse vibration frequency of the cylinder with 3 control rods is less than that for an isolated cylinder for all the configurations. The numerical results for the configurations of α=45° & 60°, G/D=0.6–1.2 show excellent suppression efficient among the cases investigated in this study. The best suppression efficient is found at α=45°, G/D=0.9 for 3 control rods. 2 rods in behind of the main cylinder perform more efficient than that of 1 rod in front for VIV suppression as the gap ratio of G/D less than 1.0.
Defective autophagy in vascular smooth muscle cells (VSMCs) is the principal cause of atherosclerosis. This study aimed to investigate the effect of astragaloside IV (AS-IV) on VSMCs autophagy. In ...vivo, ApoE−/− mice were fed with high-fat diet ad libitum for eight weeks, with or without AS-IV (25 mg/kg, daily). In vitro, human VSMCs were cultured and treated with β-Glycerophosphate (10 mmol/L) and AS-IV (50 μg/ml). VSMCs autophagy, mineralization, expression of p-ERK1/2, p-mTOR, and autophagy-related proteins (LC3 II/I, p62, and Beclin 1) were detected. Increased autophagy and mineralization was observed in VSMCs in thoracic aorta of mice and in in vitro VSMCs model of atherosclerosis. AS-IV administration attenuated the autophagy and mineralization in VSMCs. Reverse expression profiles of H19 and DUSP5 were observed. AS-IV inhibited DUSP5 and autophagy-related proteins and increased expression of H19, level of p-ERK1/2 and p-mTOR. Further, autophagy and mineralization level in VSMCs were in line with DUSP5 expression level, but in contrast to H19, p-ERK1/2, and p-mTOR profiles. We demonstrated that AS-IV could attenuate autophagy and mineralization of VSMCs in atherosclerosis, which may be associated with H19 overexpression and DUSP5 inhibition.
•H19 and DUSP5 was down- and up-regulated in atherosclerotic mice, respectively.•Astragaloside IV reduced autophagy and mineralization in VSMCs in vivo and in vitro.•DUSP5 inhibition and H19 expression prevented autophagy and mineralization in VSMCs.•ERK/mTOR activation was in contrary to autophagy and mineralization in VSMCs.
Chronic stress with lack of reward presumably may impair brain reward circuit, leading to major depressive disorder (MDD). Most individuals experiencing chronic stress do not suffer from MDD, i.e., ...resilience, implying the presence of endogenous anti-depression in the brain. Molecular mechanisms underlying stress-induced depression versus resilience were investigated. Mice were treated by chronic unpredictable mild stress (CUMS) for four weeks. Their mood state was assessed by behavioral tasks, such as sucrose preference, Y-maze and forced swimming testes. To reveal comprehensive molecular profiles of major depression versus resilience, mRNA and microRNA profiles were analyzed by high-throughput sequencing in the ventral tegmental area (VTA) harvested from control, CUMS-susceptible and CUMS-resilience mice. In data analyses of control versus CUMS-susceptible mice as well as control versus CUMS-resilience mice, 1.5 fold ratio in reads per kilo-base per million reads was set as the threshold to judge the involvement of mRNAs and microRNAs in the CUMS, depression or resilience. The downregulation of synaptic vesicle cycle, neurotrophin, GABAergic synapse and morphine addiction as well as the upregulation of transmitter release, calcium signal and cAMP-dependent response element binding are associated to CUMS-susceptibility. The downregulation of tyrosine metabolism and protein process in endoplasmic reticulum as well as the upregulation of amino acid biosynthesis, neuroactive ligand-receptor interaction and dopaminergic synapse are associated to CUMS-resilience. Therefore, the impairment of neurons and GABA/dopaminergic synapses in the VTA is associated with major depression. The upregulation of these entities is associated with resilience. Consistent results obtained from analyzing mRNAs and microRNAs as well as using different approaches strengthen our finding and conclusion.
•Many individuals do not suffer from stress-induced depression, implying endogenous anti-depression in the brain.•Neurotrophin, synaptic vesicle cycle, GABAergic synapse and morphine addiction are downregulated in CUMS-induced depression.•Amino acid biosynthesis, neuroactive ligand-receptor interaction and dopaminergic synapse are upregulated in CUMS-resilience.•The impairment of neurons and GABA/dopaminergic synapses in the VTA is associated with major depression.
•Dynamic compressive mechanical properties of alumina porous ceramic with various pore sizes are tested at high strain rates and high temperatures.•Failure characteristics of alumina porous ceramic ...in macro-scale and that of its cell wall in meso‑scale are presented.•The increase of temperature and average pore size lead to a decrease in strain rate sensitivity of it.•The strain rate and temperature effects on it have been characterized as two independent functions of proposed constitutive model.
The dynamic compressive mechanical properties of alumina porous ceramic with various average pore sizes are tested at strain rates and temperatures ranging from 0.01 s−1 to 2900 s−1 and 20 °C to 850 °C, respectively. The corresponding 3d Voronoi models are employed to simulate the meso‑characteristics of cells and failure characteristics of alumina porous ceramic in multiscale. The failure in macroscale of quasi-static compression is fragmentation, and that of dynamic compression is comminution. But in mesoscale, the failure, both of quasi-static and dynamic compression, is the fracture of cell walls. Its dynamic strength increases with the increase of strain rate, but decreases with the increase of temperature and average pore size. The increase in temperature and average pore size leads to a decrease in its strain rate sensitivity. Its Young's modulus is not sensitive to the strain rate, but increases with the decrease of average pore size, and decrease with the increase of temperature, which is presented as a temperature and average pore size dependent function. The strain rate and temperature effects are also presented by average pore size dependent functions, respectively. A constitutive model is proposed based on them. It shows that the constitutive model fits well with the experimental results.
Objectives
Major depressive disorder characterized as recurrent negative mood is one of the prevalent psychiatric diseases. Chronic stress plus lack of reward may induce long-term imbalance between ...reward and penalty circuits in the brain, leading to persistent negative mood. Numerous individuals demonstrate resilience to chronic mild stress. Molecular mechanisms for major depression and resilience in the brain remain unclear.
Methods
After juvenile mice were treated by the chronic unpredictable mild stress (CUMS) for 4 weeks, they were screened by sucrose preference, Y-maze and forced swimming tests to examine whether their behaviors were depression-like or not. mRNA and miRNA profiles were quantified by high-throughput sequencing in amygdala tissues harvested from control, CUMS-susceptible, and CUMS-resilience mice.
Results
1.5-fold ratio in reads per kilo-base per million reads was set to be the threshold to judge the involvement of mRNAs and miRNAs in the CUMS, major depression, or resilience. In the amygdala from CUMS-susceptible mice, the expression of genes relevant to GABAergic, cholinergic, glutamatergic, dopaminergic, and serotonergic synapses was changed, as well as the expression of genes that encoded signal pathways of PI3K-Akt, calcium, cAMP, MAPK, and drug addiction was imbalanced. The expression of these genes in the amygdala form CUMS-resilience mice was less changed.
Conclusions
The downregulation of genes relevant to synaptic functions and the imbalance of intra-signaling pathway in the amygdala are associated with major depression. Consistent results through sequencing mRNA and miRNA and using different methods validate our finding and conclusion.
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