Gusset joints connect only the upper and lower cover plates to the flange of aluminium alloy beams through bolts, and there is no connection to the web. To compensate for this deficiency of gusset ...joints, a new aluminium alloy flower-gusset composite joint (FGC joint) is proposed in this paper. In this paper, compression, shear and bending tests are performed on new FGC joints. The test results show that (1) compared with those of gusset joints, the compressive stiffness and bearing capacity of FGC joints increase by 2.1 and 1.36 times; (2) the shear capacity and shear stiffness of FGC joints are 1.47 times and 1.74 times higher than those of gusset joints; and (3) the bending capacity of FGC joints is 1.2 times higher than that of gusset joints, but the bending stiffnesses of the two kinds of joints are similar. Then, a numerical model is established to analyse the load transfer mechanism of FGC joints. Numerical analysis shows that the FGC joint passes axial compression through the cover plates and the flower body, shear is transmitted mainly through the flower body, and the bending moment is mainly transferred by the cover plates. Finally, based on the test and numerical analysis, the bearing capacity design method of the new joint is proposed through theoretical analysis.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Infection of influenza A virus (IAV) can trigger exaggerated pulmonary inflammation and induce acute lung injury (ALI). Limiting IAV replication and alleviation of pulmonary inflammation are two ...important therapeutic strategies for influenza virus infection. Recent studies have shown that hypoxia inducible factor-1α (HIF-1α) is an essential factor for the development and repair of ALI; however, the role and the underlying mechanisms of HIF-1α in IAV-induced ALI remain elusive. Here, we demonstrated that lung epithelial cell-specific Hif1α knockout mice infected with IAV developed more lung IAV replication and severe lung inflammation, which led to increased mortality compared to IAV-infected control mice. Moreover, knockdown of HIF1A in A549 cells (human alveolar type II epithelial cell line) promoted IAV replication in vitro. Mechanistically, knockdown of HIF1A reduced glycolysis by regulating transcription of glycolysis-related enzymes, which subsequently activated the AMPKα-ULK1 signalling pathway. Interestingly, AMPKα-ULK1 signalling promoted autophagy and augmented IAV replication. Taken together, deficiency of HIF-1α in lung epithelial cells reduces glycolysis and enhances AMPKα-ULK1-mediated autophagy, which finally facilitates IAV replication. These findings have deepened our understanding of the role of HIF-1α in regulating IAV replication and provided us novel therapeutic targets for combating influenza infection.
In previous research, the flower-gusset composite joint (FGC joint), which can replace traditional gusset joints, was proposed. The results of previous tests and numerical analysis show that the ...effect of the axial force and bolt clearance on the semi-rigid performance of FGC joints cannot be ignored. In this paper, the M-θ model of FGC joints considering the effect of the axial force and bolt clearance is proposed through theoretical analysis and test verification. First, the corresponding assumptions are proposed based on the effect of the axial force and bolt clearance on the semi-rigid performance of FGC joints. Second, the calculation formulas of the M-θ model of the FGC joint are proposed through theoretical analysis. The calculation formulas are modified by many numerical analysis results. Then, two groups of bending tests on FGC joints under different axial forces and bolt clearances are completed, and the M-θ curve of FGC joints is obtained. Finally, the M-θ curves from the tests are compared with the calculation results of the M-θ model, which show that they are very similar. Therefore, the proposed M-θ model in this paper can fully consider the effect of the axial force and bolt clearance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mesenchymal stem cells (MSCs) have been used in cell-based therapies for a variety of disorders. Some factors such as inflammatory mediators in the diseased area might damage the survival of MSCs and ...affect their efficacy. Pyroptosis is a form of programmed necrosis as a response for immune cells to cytosolic pathogenic stimuli. Whether MSCs develop pyroptosis under pathological stimulation, its underlying mechanism and biological significance are still unclear. Here, we found that LPS, flagellin, dsDNA, nigericin (NIG), or LPS combined with nigericin (LPS/NIG) could not induce pyroptosis in adipose-tissue-derived mesenchymal stem cells (ASCs). However, when applied the culture media collected from LPS/NIG-induced pyroptotic bone marrow-derived macrophages (BMDMs) to incubate ASCs, ASCs developed pyroptosis. Inhibition of caspases or deletion of Caspase-1/11 in ASCs did not affect the pyroptotic macrophage media-triggered ASC pyroptosis while ablation of Caspase-1/11 abolished BMDM pyroptosis induced by LPS/NIG. Media collected from LPS/NIG stimulated Gsdmd
or Caspase-1/11
BMDMs could not induce pyroptosis of ASCs. In addition, RNA-seq analysis showed that interferon (IFN)-stimulated genes were upregulated in pyroptotic ASCs. Adding IFNβ could boost LPS/NIG stimulated BMDM media-induced ASC pyroptosis. Surprisingly, the pyroptotic ASCs had a lower bactericidal ability to P. Aeruginosa. Taken together, induction of ASC pyroptosis requires gasdermin D or caspase-1/11-dependent mediators and IFNβ from pyroptotic macrophages.
α7 nicotinic acetylcholine receptor (α7 nAChR, coded by
) is indispensible in dampening proinflammatory responses. However, whether α7 nAChR would play a role in regulating bleomycin (BLM)-induced ...lung fibrosis is less investigated. Here, we intratracheally challenged wildtype and
mice with BLM to elicit lung fibrosis. Taken advantage of this model, we measured body weight loss, lung fibrogenic genes (
,
,
, and
), histology, Masson's trichrome staining, hydroxyproline levels, and expression of α-SMA at protein levels in the BLM-challenged lung for evaluating severity of lung fibrosis. We also pretreated human fibroblasts (MRC5 cell line) and isolated mouse lung fibroblasts with GTS-21 (an α7 nAChR agonist) to study its effects on TGF-β-stimulated profibrotic profiles. We found that lung
expression and CD4
CHAT
(Choline acetyltransferase, an enzyme for local acetylcholine synthesis) cells were 12-fold and 4.5-fold respectively elevated in the early stage of lung fibrosis. Deletion of
prevented body weight loss and reduced lung fibrogenic genes (
,
,
, and
) and
(coding arginase 1). Deletion of
attenuated lung arginase 1
Ly6C
cells, Masson's trichrome staining, hydroxyproline levels, and expression of α-SMA at protein levels in BLM-challenged mice. Mechanistically, activation of α7 nAChR in human fibroblasts increased TGF-β-induced phosphorylation of Smad2/3 and transcription of fibrogenic genes (
,
). In isolated mouse lung fibroblasts, activation of α7 nAChR also enhanced TGF-β induced-transcription of fibrogenic genes; however, deletion of
diminished these effects. Taken together, deficiency of α7 nAChR could suppress the development of BLM-induced lung fibrosis. Thus, α7 nAChR might be a novel therapeutic target for treating lung fibrosis.
To solve the problem of critical buckling in the structural analysis and design of the new long-span hollow core roof architecture proposed in this paper (referred to as a "honeycomb panel structural ...system" (HSSS)), lateral compression tests and finite element analyses were employed in this study to examine the lateral compressive buckling performance of this new type of honeycomb panel with different length-to-thickness ratios. The results led to two main conclusions: (1) Under the experimental conditions that were used, honeycomb panels with the same planar dimensions but different thicknesses had the same compressive stiffness immediately before buckling, while the lateral compressive buckling load-bearing capacity initially increased rapidly with an increasing honeycomb core thickness and then approached the same limiting value; (2) The compressive stiffnesses of test pieces with the same thickness but different lengths were different, while the maximum lateral compressive buckling loads were very similar. Overall instability failure is prone to occur in long and flexible honeycomb panels. In addition, the errors between the lateral compressive buckling loads from the experiment and the finite element simulations are within 6%, which demonstrates the effectiveness of the nonlinear finite element analysis and provides a theoretical basis for future analysis and design for this new type of spatial structure.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In previous research, an aluminum alloy honeycomb plate cylindrical reticulated shell structure was designed. The bearing capacity test and numerical analysis show that the numerical analysis model ...of honeycomb plate cylindrical reticulated shell structure is reliable. In this paper, the seismic performance of the honeycomb plate cylindrical reticulated shell structure was investigated by modal analysis and time-procedure analysis. The results show that the low-order vibration modes of the cylindrical reticulated shell structure are generally dominated by lateral translational, plane torsional or vertical vibration. The natural frequency of cylindrical reticulated shell structure with bottom plate is greater than that of cylindrical reticulated shell structure without bottom plate, which has more reasonable mass, stiffness distribution. The cylindrical reticulated shell structure with bottom plate has better seismic performance, and its deformation under rare earthquake meets the specification requirements.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, two types of beetle elytron plates (end-trabecular beetle elytron plate (EBEP) and middle-trabecular beetle elytron plate (MBEP)) and honeycomb plate (HP) were manufactured by 3-D ...printed and applied to large-span spatial structure. The lateral compressive performance of the 3-D printed beetle elytron plate was investigated by lateral compression bearing capacity test and numerical analysis. The influence of number of cylinders, ratio of the radius of the cylinder to the side length of the hexagonal honeycomb core (ratio of radius-length), thickness of core layer and configuration of beetle elytron plate on the lateral compressive performance of the beetle elytron plates were studied and the optimization method for lateral compressive performance of the beetle elytron plates was proposed. The result shows that the lateral compression bearing capacity of EBEP is greater than that of MBEP, and both are greater than of HP. The lateral compression bearing capacity of the beetle elytron plate with six cylinders is about 25% higher than that of the HP without cylinders. The lateral compression bearing capacity of beetle elytron plate can be improved by increasing the thickness of plates. The results of the study will promote the application of beetle elytron plates in large-span spatial structures.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In order to study the progressive collapse resistance of plate-member composite reticulated shell structure and propose an applicable analysis method, the complete and member removal experimental ...models of composite reticulated shell structure were designed by Alternate Path (AP) analysis method, and the progressive collapse resistance test and numerical analysis were carried out. The results show that the honeycomb plate contributes greatly to the bearing capacity of the composite structure, the ultimate bearing capacity of member removal structure is 3.64% smaller than that of the complete structure, and the ultimate displacement is 30% smaller. The average error of load-displacement curves between the progressive collapse resistance test and numerical analysis is less than 10% in the elastic stage, and the overall failure mode of the numerical analysis model and the experimental model is consistent. The anti-progressive collapse analysis method based on modal sensitivity is suitable for the plate-member composite reticulated shell structure due to high computational efficiency and accuracy, which provides a reference for progressive collapse resistance analysis of plate-member composite reticulated shell structure.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This article proposes a new type of single-layer combined lattice shell (NSCLS); which is based on aluminum alloy honeycomb panels. Six models with initial geometric defect were designed and ...precision made using numerical control equipment. The stability of these models was tested. The results showed that the stable bearing capacity of NSCLS was approximately 16% higher than that of a lattice shell with the same span without a reinforcing plate. At the same time; the properties of the NSCLS were sensitive to defects. When defects were present; its stable bearing capacity was decreased by 12.3% when compared with the defect-free model. The model with random defects following a truncated Gaussian distribution could be used to simulate the distribution of defects in the NSCLS. The average difference between the results of the nonlinear analysis and the experimental results was 5.7%. By calculating and analyzing nearly 20,000 NSCLS; the suggested values of initial geometric defect were presented. The results of this paper could provide a theoretical basis for making and revising the design codes for this new combined lattice shell structure.
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