Study on Shear Performance of Short Bolt Interface in ECC–Steel Bridge Deck Composite Structure

Aiming at the problem that orthotropic steel bridge deck and bridge deck pavement are prone to fatigue damage, Engineered Cementitious Composites (ECC) bridge deck pavement is used to replace concrete or asphalt in flexible bridge deck pavement. In order to deeply explore the shear resistance of the short stud interface in the ECC–steel composite structure and provide theoretical support for the practical application of the project, 16 static push-out tests were completed. The effects of stud diameter, height and arrangement spacing on the shear capacity of the medium and short ECC studs were studied. The failure modes, load–slip curves, load–strain curves and interface gap width curves of the components were analyzed. The test results showed that the shear force of the medium and short ECC bolts mainly produces two failure modes, bolt shearing and bolt root weld shearing, while the ECC plate has a local crushing area at the interface bolt root position, and no large cracks occur in other areas. The shear capacity of short bolts is significantly affected by the diameter of the bolts, but is less affected by the height and spacing of the bolts, and increases with the diameter of the short bolts. The length of the stud has an important influence on the stress on the surface of the ECC board. The longer the stud, the greater the tensile stress on the ECC surface. The shorter the peg, the more prone to eccentric compression the ECC plate is, and the longer the peg, the more prone to axial compression it is

Theoretical Analysis and Experimental Verification of the Stress and Strain of Axially Compressed Steel-Reinforced Concrete Columns under Long-Term Loads

The objective of this study is to provide a theoretical method to accurately calculate the stress and strain of steel-reinforced concrete (SRC) columns under long-term axial compression. First, considering the cross-sectional stress redistribution and the influence of each stress increment in the process, the theoretical formula of stress and strain under long-term loading was deduced. Then, the stress and strain calculation program of SRC columns under long-term axial compression was programmed by using object-oriented Visual C++ language. Finally, an experimental study on the long-term deformation performance of SRC axial compression columns was performed to validate the accuracy of the proposed theoretical method. By comparing the calculated results with the experimental results, the influence of steel bars on the long-term stress and strain of SRC columns under axial compression was analyzed and the corresponding long-term stress–strain variation law was studied. Results show that the changing trend of the long-term strain of plain concrete (PC) and SRC with loading time is basically the same, increasing rapidly in the first 270 days and gradually tending to be stable beyond 270 days. After 750 days, the maximum difference in the total strain between the PC columns and SRC columns reaches 26.60%, and the steel bars have a strong influence on the long-term strain of the concrete columns. The errors between the measured values of the two SRC columns, and the calculated results are 2.96% and 5.78%, respectively. Therefore, the derived stress–strain calculation formula and calculation program of SRC columns under long-term loads are accurate and reliable. When the loading time is 750 days, the tensile stress increment of 1.92 MPa and a compressive stress increment of 168.26 MPa are produced in concrete and steel bars. The long-term stress of concrete columns is markedly influenced by steel bars. In the first three years, the stress and strain of the concrete and steel bars develop rapidly and then gradually slow down

Study on Shear Performance of Short Bolt Interface in ECC–Steel Bridge Deck Composite Structure

Aiming at the problem that orthotropic steel bridge deck and bridge deck pavement are prone to fatigue damage, Engineered Cementitious Composites (ECC) bridge deck pavement is used to replace concrete or asphalt in flexible bridge deck pavement. In order to deeply explore the shear resistance of the short stud interface in the ECC–steel composite structure and provide theoretical support for the practical application of the project, 16 static push-out tests were completed. The effects of stud diameter, height and arrangement spacing on the shear capacity of the medium and short ECC studs were studied. The failure modes, load–slip curves, load–strain curves and interface gap width curves of the components were analyzed. The test results showed that the shear force of the medium and short ECC bolts mainly produces two failure modes, bolt shearing and bolt root weld shearing, while the ECC plate has a local crushing area at the interface bolt root position, and no large cracks occur in other areas. The shear capacity of short bolts is significantly affected by the diameter of the bolts, but is less affected by the height and spacing of the bolts, and increases with the diameter of the short bolts. The length of the stud has an important influence on the stress on the surface of the ECC board. The longer the stud, the greater the tensile stress on the ECC surface. The shorter the peg, the more prone to eccentric compression the ECC plate is, and the longer the peg, the more prone to axial compression it is

Different Oligosaccharides Induce Coordination and Promotion of Root Growth and Leaf Senescence during Strawberry and Cucumber Growth

Oligosaccharides, as a wide type of polysaccharide, have a broad antimicrobial spectrum and promote development as plant growth stimulants. To investigate the regulation effects of different oligosaccharides on the dynamic changes of chlorophyll content, leaf fluorescence, root activity and morphology, and chloroplast ultrastructure, as well as the yields and yield components of strawberry and cucumber, typical greenhouse experiments were conducted over two years (2021–2022). The experimental plants were foliar sprayed with tap water (CK), chitosan oligosaccharide (CSOS), and mixed oligosaccharides (MixOS) five times before flowering. The conventional management (CM) was conducted as a conventional control. The findings of the present study suggest that the application of MixOS has the greatest regulation effects on delayed leaf senescence, well-developed roots, and higher fruit productions of strawberry and cucumber. Exogenous MixOS resulted in significant increases in SPAD values, maximum photochemical efficiency (Fv/Fm), and photochemical quenching coefficiency (qP); they were increased by 1.94–28.96%, 5.41–33.89%, and 9.93–62.07%, compared to the CSOS, CM, and CK treatments, respectively. The orderly and steady structure of thylakoids in the chloroplast, and the randomly distributed starch grains, could be clearly observed in the MixOS treatment, while the non-photochemical quenching (NPQ) was correspondingly reduced by 19.04–45.92%. Meanwhile, the remarkable promotion of root activity and root surface morphology indicators (i.e., root length, surface area, average diameter, and volume) could be observed when exposed to the MixOS treatments, and the total yields of strawberry and cucumber were all increased by 12.40–25.57%. These findings suggest that the mixed oligosaccharides mainly promote the coordinated growth of root and shoot, which leads to the improved yields of strawberry and cucumber

N1-Methyladenosine modification of mRNA regulates neuronal gene expression and oxygen glucose deprivation/reoxygenation induction

Abstract N1-Methyladenosine (m1A) is an abundant modification of transcripts, plays important roles in regulating mRNA structure and translation efficiency, and is dynamically regulated under stress. However, the characteristics and functions of mRNA m1A modification in primary neurons and oxygen glucose deprivation/reoxygenation (OGD/R) induced remain unclear. We first constructed a mouse cortical neuron OGD/R model and then used methylated RNA immunoprecipitation (MeRIP) and sequencing technology to demonstrate that m1A modification is abundant in neuron mRNAs and dynamically regulated during OGD/R induction. Our study suggests that Trmt10c, Alkbh3, and Ythdf3 may be m1A-regulating enzymes in neurons during OGD/R induction. The level and pattern of m1A modification change significantly during OGD/R induction, and differential methylation is closely associated with the nervous system. Our findings show that m1A peaks in cortical neurons aggregate at both the 5’ and 3’ untranslated regions. m1A modification can regulate gene expression, and peaks in different regions have different effects on gene expression. By analysing m1A-seq and RNA-seq data, we show a positive correlation between differentially methylated m1A peaks and gene expression. The correlation was verified by using qRT-PCR and MeRIP-RT-PCR. Moreover, we selected human tissue samples from Parkinson’s disease (PD) and Alzheimer’s disease (AD) patients from the Gene Expression Comprehensive (GEO) database to analyse the selected differentially expressed genes (DEGs) and differential methylation modification regulatory enzymes, respectively, and found similar differential expression results. We highlight the potential relationship between m1A modification and neuronal apoptosis following OGD/R induction. Furthermore, by mapping mouse cortical neurons and OGD/R-induced modification characteristics, we reveal the important role of m1A modification in OGD/R and gene expression regulation, providing new ideas for research on neurological damage

Crosstalk between m6A mRNAs and m6A circRNAs and the time-specific biogenesis of m6A circRNAs after OGD/R in primary neurons

Cerebral ischaemiareperfusion injury is an important pathological process in nervous system diseases during which neurons undergo oxygenglucose deprivation and reoxygenation (OGD/R) injury. No study has used epitranscriptomics to explore the characteristics and mechanism of injury. N6methyladenosine (m6A) is the most abundant epitranscriptomic RNA modification. However, little is known about m6A modifications in neurons, especially during OGD/R. m6A RNA immunoprecipitation sequencing (MeRIPseq) and RNA-sequencing data for normal and OGD/R-treated neurons were analysed by bioinformatics. MeRIP quantitative real-time polymerase chain reaction was used to determine the m6A modification levels on specific RNAs. We report the m6A modification profiles of the mRNA and circRNA transcriptomes of normal and OGD/R-treated neurons. Expression analysis revealed that the m6A levels did not affect m6A mRNA or m6A circRNA expression. We found crosstalk between m6A mRNAs and m6A circRNAs and identified three patterns of m6A circRNA production in neurons; thus, distinct OGD/R treatments induced the same genes to generate different m6A circRNAs. Additionally, m6A circRNA biogenesis during distinct OGD/R processes was found to be time specific. These results expand our understanding of m6A modifications in normal and OGD/R-treated neurons, providing a reference to explore epigenetic mechanisms and potential treatments for OGD/R-related diseases