As important components of transmission tower-line systems, tension towers are used mainly at the corner of the line or among several suspension towers to prevent their progressive collapse under ...extreme loading conditions. Compared with suspension towers, tension towers exhibit more complicated stress states and different failure patterns. Under the activities of various disasters, the failure of tension towers will result in more serious consequences, but their failure mechanism is seldom investigated. In this paper, the stress and displacement distributions of a tension tower under eight different loading cases are analyzed based on a full-scale test. The test tower successfully passes a 100% loading step test under the first seven loading cases and is overloaded to collapse under Case 8. Then, the finite element model (FEM) of the test tower is established, and the buckling instability of members is simulated by applying initial imperfections. The calculated critical loading level and member strains are in good agreement with the full-scale test results, verifying the reliability of the FEM and analysis method. Finally, the pushover analysis is performed to simulate the failure pattern of the tension tower, and the results demonstrate that the failure mode is the shear failure. Plastic failure occurs firstly in the diagonal members of the cross arm under compression, after which the main members yield quickly, completely forfeiting the bearing capacity of the tower. For the tension tower employed in this test, the diagonal members under compression play a decisive role in the ultimate bearing capacity.
•The upper diagonal members are the initial failure positions, accelerating the buckling of the lower diagonal members.•The numerical simulation confirms that the FEM and analysis method are reliable by comparing with the full-scale test.•FEM has the advantage of providing every detail of tower response, capturing the plastic deformation and bearing capacity.•In design stage for a tension tower, the diagonal member of the cross arm is one of the critical positions.
China’s natural gas supply has been challenged in the past few years by non-traditional risks such as trading conflicts, the COVID-19 pandemic, and the country’s own emission policy. To ensure energy ...security and supply, conducting an up-to-date risk analysis of China’s natural gas supply status is crucial. This research utilized the Fuzzy-AHP method to compose a risk index and assessed the key links within China’s natural gas supply chain from the import side to the domestic side. The results indicate that (a) for China’s gas import, the most influential risks are the correlated dependence risk, international relation risk, and supplier internal stability risk. (b) While the dependence risk and transport risk have decreased sharply in the past decade, the import risk is still China’s major concern on natural gas supply. (c) Emissions-peaking and carbon neutrality targets are potential challenges, which the country would possibly face in the near future.
•Computational simulation of 3D structures of two molecules and four phenothiazines.•Synthesis of two dummy templates based molecularly imprinted polymers (MIP).•Develop a MIP-SPE column for ...determination of phenothiazines residues in meats.
The 3D structures of two dummy templates and four phenothiazine drugs were studied by using computational simulation method. Then the two dummy templates were used to synthesize two molecularly imprinted polymers respectively. Results showed that the recognition abilities of the two polymers were consistent with the theoretical calculation. Then a solid phase extraction column was developed for extraction of the four phenothiazines in meat (pork, chicken) followed by determination with high performance liquid chromatography. The column showed high adsorption capacities (850–962ng analyte per milligram of polymer) and high recoveries (93–98%) to the four drugs, and could be recycled for sixty times. The limits of detection were in the range of 1.0–10ng/g, and the recoveries from the fortified blank samples were in the range of 70.3–96.1%. This is the first study reporting the use of molecularly imprinted polymer-based method for determination of phenothiazines residues in foods.
Using an established acoustoelectric signal testing system, we conducted a series of experiments on coal rock samples of lower strength under uniaxial compression and shear loading to study the ...characteristics of ultralow frequency (ULF) electromagnetic radiation (EMR) signals emitted during their damage and failure, compared them with signals of very low frequency (VLF) (5kHz), middle frequency (MF) (300kHz) and acoustic emission (AE) (42.3kHz), and explored the generation mechanism of this ULF EMR. Using our self-developed ULF signal acquisition instruments, we monitored the ULF EMR signals at the mining face, and studied the space and time distribution laws of ULF EMR in the front of the mining face. The results showed that the coal rock materials subject to uniaxial compression and shear loading can produce ULF EMR signals, which are well correlated with stress, and AE signals. The ULF signals emitted from the two processes are caused firstly by the changes in the induction field due to charges moving and secondly by the piezomagnetic effect resulting from some metal minerals in the coal rock materials after applying stress. Under rock pressure in mines, the coal mass ahead of the face during its deformation and failure emits strong ULF EMR with a strong ability to resist interference. The time and space distributions of these EMR are well correlated with stress in coal mass in the front of the mining face.
•Coal rock subject to uniaxial compression and shear loading can produce ULF EMR signals.•It is mainly generated by the low-speed diffusion of charges and the change in the amount.•We use our self-developed ULF signal acquisition instrument in field applications.
The crack-tip atomic stress distributions and microstructure evolutions of the intergranular crack in bicrystalline nickel at different temperatures. Display omitted
•Molecular dynamics-based ...cohesive zone model is used to study intergranular fracture.•The relationship between the stress field and microstructural evolution is analyzed.•Temperature dependence of mechanisms of intergranular fracture is revealed.•The stress and opening displacement relations are obtained at different temperatures.
In this study, we find microstructure mechanisms and stress distributions around the crack-tip of an intergranular fracture process in bicrystal nickel are strongly dependent on temperature by using a molecular dynamics (MD)-based cohesive zone model (CZM). At a lower temperature, deformation twinning occurs in the two opposite directions along the grain boundary, and the crack propagation eventually forms an intergranular fracture. As the temperature increasing, deformation twinning is becoming increasingly hard to occur around the crack-tip along the grain boundary but more readily to generate the slip bands, and the crack propagation will not form intergranular fracture along the grain boundary. Moreover, based on the calculation of CZM, the slip bands are stronger to prevent intergranular crack growth than deformation twinning around the crack-tip, and a high stress is found in the region of microstructure evolution near the crack-tip. The present results may provide useful information for understanding intergranular fracture mechanisms and stress distributions at the atomic-scale.
We propose a modified definition for a quasiparton distribution function (QPDF) with an equal-time correlator in the large momentum limit, whose two pieces of spacelike Wilson links are oriented in ...orthogonal directions. It is explicitly shown at the one-loop level that the linear divergence in the original QPDF with dipolar Wilson links, which complicates its matching to the standard light-cone parton distribution function (LPDF), is removed. The LPDF can then be extracted reliably from Euclidean lattice data for the QPDF with the nondipolar Wilson links.
Intestinal luminal microbiota likely contribute to the etiology of necrotizing enterocolitis (NEC), a common disease in preterm infants. Microbiota development, a cascade of initial colonization ...events leading to the establishment of a diverse commensal microbiota, can now be studied in preterm infants using powerful molecular tools. Starting with the first stool and continuing until discharge, weekly stool specimens were collected prospectively from infants with gestational ages ≤32 completed weeks or birth weights≤1250 g. High throughput 16S rRNA sequencing was used to compare the diversity of microbiota and the prevalence of specific bacterial signatures in nine NEC infants and in nine matched controls. After removal of short and low quality reads we retained a total of 110,021 sequences. Microbiota composition differed in the matched samples collected 1 week but not <72 hours prior to NEC diagnosis. We detected a bloom (34% increase) of Proteobacteria and a decrease (32%) in Firmicutes in NEC cases between the 1 week and <72 hour samples. No significant change was identified in the controls. At both time points, molecular signatures were identified that were increased in NEC cases. One of the bacterial signatures detected more frequently in NEC cases (p<0.01) matched closest to γ-Proteobacteria. Although this sequence grouped to the well-studied Enterobacteriaceae family, it did not match any sequence in Genbank by more than 97%. Our observations suggest that abnormal patterns of microbiota and potentially a novel pathogen contribute to the etiology of NEC.
, an endophytic fungus associated with the herbal medicine
, produced four new polyketides, aspeversins A-D (1-2 and 5-6) and four known compounds,
-methylaverufin (2), aversin (3), varilactone A (7) ...and spirosorbicillinol A (8). Their structures were elucidated by extensive spectroscopic data analysis, and their absolute configurations were determined by calculated electronic circular dichroism (ECD) and Mo
(AcO)
-induced CD data. Compound 5 was found to exhibit α-glucosidase inhibitory activity with an IC
value of 25.57 μM. An enzyme kinetic study indicated that 5 was a typical uncompetitive inhibitor toward α-glucosidase, which was supported by a molecular docking study. Moreover, compounds 1-3 and 5 also improved the cell viability of PC12 cells on a 1-methyl-4-phenylpyridinium (MPP
)-induced Parkinson's disease model, indicating their neuroprotective potential as antiparkinsonian agents.
Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in ...glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.
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