To better understand the creep mechanical behavior of salt rock under very long-term tests and more accurately predict the long-term deformation of the salt caverns, a series of long-term uniaxial ...creep tests lasting for 21000 h (875 days) were carried out. The results show that the creep strain and creep rate of salt rock increase with the increase of axial stress. The initial creep stage under lower stresses lasted for 4.3–8.3 months, which was much higher than that under high stresses. Predicting the true creep rate of the salt cavern based on the test results of the creep rate in this paper is more accurate than the existing research results. A new nonlinear creep-damage constitutive model is proposed by introducing the nonlinear damage body and using the fractional derivative theory. Using the presented model and the classic creep constitutive models to fit the experimental data, it is found that the presented model best characterizes the creep evolution characteristics of salt rock. The fitting function obtained from the experimental data at different times predicts the final creep results, revealing that the longer the test duration, the more accurate the predicted results. The research in this paper provides the necessary basis for intensive investigation and prediction of the long-term creep mechanical behavior of salt storage caverns.
N6‐methyladenosine (m6A) is a well‐known modification of RNA. However, as a key m6A methyltransferase, METTL16 has not been thoroughly studied in gastric cancer (GC). Here, the biological role of ...METTL16 in GC and its underlying mechanism was studied. Immunohistochemistry was used to detect the expression of METTL16 and relationship between METTL16 level and prognosis of GC was analysed. CCK8, colony formation assay, EdU assay and xenograft mouse model were used to study the effect of METTL16. Regulatory mechanism of METTL16 in the progression of GC was studied through flow cytometry analysis, RNA degradation assay, methyltransferase inhibition assay, RT‐qPCR and Western blotting. METTL16 was highly expressed in GC cells and tissues and was associated with prognosis. In vitro and in vivo experiments confirmed that METTL16 promoted proliferation of GC cells and tumour growth. Furthermore, down‐regulation of METTL16 inhibited proliferation by G1/S blocking. Significantly, we identified cyclin D1 as a downstream effector of METTL16. Knock‐down METTL16 decreased the overall level of m6A and the stability of cyclin D1 mRNA in GC cells. Meanwhile, inhibition of methyltransferase activity reduced the level of cyclin D1. METTL16‐mediated m6A methylation promotes proliferation of GC cells through enhancing cyclin D1 expression.
The first of a new generation of microwave sounders was launched aboard the Suomi‐National Polar‐Orbiting Partnership satellite in October 2011. The Advanced Technology Microwave Sounder (ATMS) ...combines the capabilities and channel sets of three predecessor sounders into a single package to provide information on the atmospheric vertical temperature and moisture profiles that are the most critical observations needed for numerical weather forecast models. Enhancements include size/mass/power approximately one third of the previous total, three new sounding channels, the first space‐based, Nyquist‐sampled cross‐track microwave temperature soundings for improved fusion with infrared soundings, plus improved temperature control and reliability. This paper describes the ATMS characteristics versus its predecessor, the advanced microwave sounding unit (AMSU), and presents the first comprehensive evaluation of key prelaunch and on‐orbit performance parameters. Two‐year on‐orbit performance shows that the ATMS has maintained very stable radiometric sensitivity, in agreement with prelaunch data, meeting requirements for all channels (with margins of ~40% for channels 1–15), and improvements over AMSU‐A when processed for equivalent spatial resolution. The radiometric accuracy, determined by analysis from ground test measurements, and using on‐orbit instrument temperatures, also shows large margins relative to requirements (specified as <1.0 K for channels 1, 2, and 16–22 and <0.75 K for channels 3–15). A thorough evaluation of the performance of ATMS is especially important for this first proto‐flight model unit of what will eventually be a series of ATMS sensors providing operational sounding capability for the U.S. and its international partners well into the next decade.
Key Points
First flight unit performing well
On‐orbit evaluations of ATMS performance are presented
The mechanical characteristics and gas tightness of salt rock play a decisive role in the safety evaluation of salt caverns. Triaxial compression coupled permeability tests were performed on Chinese ...impure salt rocks under thermal-hydro-mechanical (THM) coupling condition. The results revealed that the peak strength decreased with the decrease of confining pressure and the increase of temperature. The permeability of salt rock decreased with the increase of confining pressure, while the increase of temperature led to an increase in permeability under lower effective confining pressure, and a decrease in permeability under higher effective confining pressure. Moreover, there is a critical effective confining pressure, which controls the evolution trend of salt rock permeability with temperature. The dilatancy boundary and failure strength envelope of impure salt rock at different temperatures were given, which can be expressed by exponential and hyperbolic functions respectively. An empirical formula for the evolution of the final permeability of the salt rock with the effective confining pressure at different temperatures was established. Considering the effects of effective confining pressure and inelastic volume strain, a new model was proposed to predict the permeability evolution of salt rock under THM coupling condition at different temperatures. The results of this paper can help understand the mechanical characteristics and permeability evolution of salt rock under THM coupling condition, and provide the necessary basis for the safety evaluation of salt caverns.
•The mechanical characteristics of salt rock under THM coupling was obtained.•The permeability evolution of salt rock under THM coupling was investigated.•The expansion boundary of salt rock under THM coupling was given.•A novel model for predicting permeability evolution of salt rock was proposed.
Despite the wide applications, systematic mechanobiological investigation of 3D porous scaffolds has yet to be performed due to the lack of methodologies for decoupling the complex interplay between ...structural and mechanical properties. Here, we discover the regulatory effect of cryoprotectants on ice crystal growth and use this property to realize separate control of the scaffold pore size and stiffness. Fibroblasts and macrophages are sensitive to both structural and mechanical properties of the gelatin scaffolds, particularly to pore sizes. Interestingly, macrophages within smaller and softer pores exhibit pro-inflammatory phenotype, whereas anti-inflammatory phenotype is induced by larger and stiffer pores. The structure-regulated cellular mechano-responsiveness is attributed to the physical confinement caused by pores or osmotic pressure. Finally, in vivo stimulation of endogenous fibroblasts and macrophages by implanted scaffolds produce mechano-responses similar to the corresponding cells in vitro, indicating that the physical properties of scaffolds can be leveraged to modulate tissue regeneration.
Transposable elements (TEs) are a significant component of eukaryotic genomes and play essential roles in genome evolution. Mounting evidence indicates that TEs are highly transcribed in early embryo ...development and contribute to distinct biological functions and tissue morphology.
We examine the epigenetic dynamics of mouse TEs during the development of five tissues: intestine, liver, lung, stomach, and kidney. We found that TEs are associated with over 20% of open chromatin regions during development. Close to half of these accessible TEs are only activated in a single tissue and a specific developmental stage. Most accessible TEs are rodent-specific. Across these five tissues, 453 accessible TEs are found to create the transcription start sites of downstream genes in mouse, including 117 protein-coding genes and 144 lincRNA genes, 93.7% of which are mouse-specific. Species-specific TE-derived transcription start sites are found to drive the expression of tissue-specific genes and change their tissue-specific expression patterns during evolution.
Our results suggest that TE insertions increase the regulatory potential of the genome, and some TEs have been domesticated to become a crucial component of gene and regulate tissue-specific expression during mouse tissue development.
1,4,5,8,9,12‐Hexaazatriphenylene (HAT) is one of the smallest polyheterocyclic aromatic building blocks for forming conjugated metal–organic frameworks (cMOFs). However, the strong inter‐molecular ...steric hindrance impedes the growth of HAT‐based cMOFs. Here we employ on‐surface synthesis to grow single‐layer two‐dimensional cMOFs of M3(HAT)2 (M=Ni, Fe, Co). Using scanning tunnelling microscopy and density‐functional theory (DFT) analysis, we resolve that the frameworks comprise a hexagonal lattice of HAT molecules and a Kagome lattice of metal atoms. The DFT analysis indicates that Ni, Co and Fe carry a magnetic moment of 1.1, 2.5, and 3.7 μB, respectively. We anticipate that the small π‐conjugated core of HAT and strong bidentate chelating coordination give rise to appealing electronic and magnetic properties.
1,4,5,8,9,12‐Hexaazatriphenylene (HAT)‐based two‐dimensional conjugated metal–organic frameworks of M3(HAT)2 (M=Fe, Ni, Co) were synthesized by means of an on‐surface self‐assembly protocol which effectively overcomes the strong inter‐molecular steric hindrance.
To clarify the shear-slip process and characteristics of fault, we conducted triaxial shear tests driven by displacement on shale samples with prefabricated sawcut and natural fractures, and the ...acoustic emission (AE) technology was used to monitor the shear-slip process in real-time. According to the test results, the shear-slip process and mechanical characteristics of sawcut and natural fractures were analyzed. The test results indicate that the shear-slip process of fractures can be divided into four stages, improving the confining pressure will cause more serious plastic failure in the shear-slip process, and the increase of roughness will make the phenomenon of “stress drop” more obvious, which is closely related to the earthquake occurrence. Confining pressure and roughness all have implications for the stress thresholds of each stage. With the transition of shear-slip stages, the effects of confining pressure and roughness on the shear-slip of fractures are more drastic. The maximum static friction coefficient μ0 increases with initial roughness increasing and is independent of confining pressure. Due to the strain-strengthening effect of fracture slip, the average value of dynamic friction coefficient μd under simple shear deformation is greater than the maximum static friction coefficient μ0. Based on AE response characteristics, microcracks development, and rupture scale during the shear-slip process were also explored. AE events are mainly distributed along the inclined fracture. The AE response in different shear-slip stages displays pronounced differences, and the AE evolution and macro mechanical characteristics of fractures show significant time-synchronization. The variation of peak frequency can reflect the rupture scale transformation and the influence of confining pressure and roughness. Additionally, the differences in the morphological evolution of sawcut and natural fractures are mainly reflected in the wear pattern, degree and the rock debris attach amount. Finally, we also discussed the micro-deformation mechanism of asperities during the shear-slip process. This work may provide a reference for the research of fault activation and slip in shale reservoirs.
•Triaxial shear tests driven by displacement on shale samples with prefabricated sawcut and natural fractures were carried out.•Shear-slip process and acoustic emission (AE) evolution of sawcut and natural fractures in shale were analyzed.•Morphological evolution and characteristics of fracture surfaces before and after the test were revealed.•Micro-deformation mechanism of asperities during the shear-slip process was clarified.
Vision influences behavior, but ongoing behavior also modulates vision in animals ranging from insects to primates. The function and biophysical mechanisms of most such modulations remain unresolved. ...Here, we combine behavioral genetics, electrophysiology, and high-speed videography to advance a function for behavioral modulations of visual processing in Drosophila. We argue that a set of motion-sensitive visual neurons regulate gaze-stabilizing head movements. We describe how, during flight turns, Drosophila perform a set of head movements that require silencing their gaze-stability reflexes along the primary rotation axis of the turn. Consistent with this behavioral requirement, we find pervasive motor-related inputs to the visual neurons, which quantitatively silence their predicted visual responses to rotations around the relevant axis while preserving sensitivity around other axes. This work proposes a function for a behavioral modulation of visual processing and illustrates how the brain can remove one sensory signal from a circuit carrying multiple related signals.
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•Optic flow-processing neurons participate in controlling head stability responses•During flight turns, these neurons receive precisely tuned motor-related inputs•These inputs suppress specific visual responses while preserving other responses•These modulations of visual signaling mute maladaptive head movements during turns
In flying Drosophila, quantitatively tailored motor-related inputs modulate visual processing via a sophisticated subtractive computation, allowing removal of a specific sensory signal from a complex circuit carrying multiple related signals.
This paper focuses on analyzing the mechanical properties, permeability and energy characteristics of limestone from coal measures strata of through-coal seam (TCS) tunnel in the context of the ...Taoziya tunnel as the engineering background. The improved MTS815 Flex test GT rock mechanics system and acoustic emission (AE) technology were utilized for the triaxial compression with permeability test of limestone from coal measures strata of TCS tunnel. The results indicate that gas pressure and confining pressure significantly affect the mechanical properties and permeability of limestone from coal measures strata of TCS tunnel. The gas pressure promotes the development and propagation of cracks, whereas increasing confining pressure strengthens the resistance of limestone samples to crack propagation. When limestone samples transition from the initial compaction stage to the unstable cracks propagation stage, the possibility of gas leakage during tunneling in the coal measures strata should be recognized, and the stability of surrounding rock should focus on the failure stage. In the process of progressive failure of limestone samples, AE events with larger amplitude are distributed near the main macroscopic fracture zone, and the distribution of AE events closely corresponds to the macroscopic failure mode of limestone samples. Exponential functions can be used to describe the trend of initial permeability ki, peak permeability kp and residual permeability kr decreasing with effective confining pressure σe. The closure and propagation of microcracks are the fundamental reason for the corresponding relationship between the stress variation process, AE characteristics and permeability of limestone samples. Finally, the energy characteristics of limestone under triaxial compression were analyzed based on the stress-strain curves of limestone. This study may give fresh insights and necessary references to ensure the safe construction and development of TCS tunnels.
•Mechanical properties of limestone from coal measures strata of TCS tunnel were studied.•Initiation and propagation of cracks in limestone samples were studied.•Relationship between cracks development and permeability of limestone was revealed.•Energy characteristics of limestone under triaxial compression were clarified.
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