Photonics-assisted microwave pulse detection and frequency measurement based on pulse replication and frequency-to-time mapping.

A photonics-assisted microwave pulse detection and frequency measurement scheme is proposed. The unknown microwave pulse is converted to the optical domain and then injected into a fiber loop for pulse replication, which makes it easier to identify the microwave pulse with a large pulse repetition interval (PRI), whereas stimulated Brillouin scattering-based frequency-to-time mapping (FTTM) is utilized to measure the carrier frequency of the microwave pulse. A sweep optical carrier is generated and modulated by the unknown microwave pulse and a continuous-wave (CW) single-frequency reference, generating two different frequency sweep optical signals, which are combined and used as the probe wave to detect a fixed Brillouin gain spectrum. When the optical signal is detected in a photodetector, FTTM is realized, and the frequency of the microwave pulse can be determined. An experiment is performed. For a fiber loop containing a 210-m fiber, pulse replication and FTTM of the pulses with a PRI of 20 µs and pulse widths of 1.20, 1.00, 0.85, and 0.65 µs are realized. Under a certain frequency sweep chirp rate of 0.978 THz/s, the measurement errors are below ±12 and ±5MHz by using one pair of pulses and multiple pairs of pulses, respectively. The influence of the frequency sweep chirp rate and pulse width on the measurement error has also been studied. To a certain extent, the faster the frequency sweep, the greater the frequency measurement error. For a specific frequency sweep chirp rate, the measurement error is almost unaffected by the pulse width to be measured.

MdARF3 switches the lateral root elongation to regulate dwarfing in apple plants.

Apple rootstock dwarfing and dense planting are common practices in apple farming. However, the dwarfing mechanisms are not understood. In our study, the expression of MdARF3 in the root system of dwarfing rootstock 'M9' was lower than in the vigorous rootstock from Malus micromalus due to the deletion of the WUSATAg element in the promoter of the 'M9' genotype. Notably, this deletion variation was significantly associated with dwarfing rootstocks. Subsequently, transgenic tobacco (Nicotiana tabacum) cv. Xanthi was generated with the ARF3 promoter from 'M9' and M. micromalus genotypes. The transgenic apple with 35S::MdARF3 was also obtained. The transgenic tobacco and apple with the highly expressed ARF3 had a longer root system and a higher plant height phenotype. Furthermore, the yeast one-hybrid, luciferase, electrophoretic mobility shift assays, and Chip-qPCR identified MdWOX4-1 in apples that interacted with the pMm-ARF3 promoter but not the pM9-ARF3 promoter. Notably, MdWOX4-1 significantly increased the transcriptional activity of MdARF3 and MdLBD16-2. However, MdARF3 significantly decreased the transcriptional activity of MdLBD16-2. Further analysis revealed that MdARF3 and MdLBD16-2 were temporally expressed during different stages of lateral root development. pMdLBD16-2 was mainly expressed during the early stage of lateral root development, which promoted lateral root production. On the contrary, pMmARF3 was expressed during the late stage of lateral root development to promote elongation. The findings in our study will shed light on the genetic causes of apple plant dwarfism and provide strategies for molecular breeding of dwarfing apple rootstocks.

Genome-wide identification of WOX family members in nine Rosaceae species and a functional analysis of MdWOX13-1 in drought resistance.

WUSCHEL-related homeobox (WOX) transcription factors (TFs) are important in plant development processes and evolutionary novelties. In this study, a genome-wide comprehensive analysis of WOX genes from nine Rosaceae species was carried out, and their potential roles in Malus were subsequently investigated. 125 WOXs in 9 Rosaceae species were identified and classified into three clades, i.e., the ancient, intermediate, and WUS clades. Prunus. domestica contained the most intra-genomic collinearity among the nine Rosaceae species. Additionally, the cis-elements in WOX gene family members were compared and classified into three categories, including phytohormone-responsive, plant growth and development, and abiotic and biotic stresses. Overexpression (OE) of MdWOX13-1 also increased the callus weight and enhanced ROS scavenging against drought stress. Furthermore, via yeast-one hybrid assay and LUC analyses, MdWOX13-1 could directly bind to the MdMnSOD promoter. Therefore, our results will facilitate further study of the WOX genes' function in the Rosaceae family.

MdGRF11-MdARF19-2 module acts as a positive regulator of drought resistance in apple rootstock.

14-3-3 proteins play an important role in the response of plants to drought resistance. In this study, 14-3-3 protein MdGRF11 was cloned from Malus xiaojinensis, and its positive regulation of drought resistance was verified using Orin calli and M. xiaojinensis plants. The transcription factor MdARF19-2 was further screened for interaction with this protein in vitro and in vivo. We also conducted experiments using Orin calli and found that the overexpression of MdARF19-2 decreased the level of reactive oxygen species (ROS) and increased the activity of enzymes that scavenge ROS in plant materials. This indicates that MdARF19-2 is a positive regulator in the drought resistance of plants. The drought tolerance was further improved by the overexpression of both MdGRF11 and MdARF19-2 in the calli. In addition, we examined several genes related to ROS scavenging with auxin response factor binding elements in their promoters and found that their level of expression was regulated by the MdGRF11-MdARF19-2 module. In conclusion, the enhancement of plant drought resistance by MdGRF11 could be owing to its accumulation at the protein level in response to drought, which then combined with MdARF19-2, affecting the expression of MdARF19-2 downstream genes. Thus, it scavenges ROS, which ultimately improves the resistance of plant to drought stress.

Study on the Seismic Performance of Stiffened Corrugated Steel Plate Shear Walls with Atmospheric Corrosion.

Corrugated steel plate shear walls (CSPWs) with three different stiffening methods are proposed in this paper, including unstiffened CSPWs (USWs), cross stiffened CSPWs (CSWs) and asymmetric diagonal-stiffened CSPWs (ASWs). A numerical model was established by ABAQUS 6.13 based on the validation of an existing cyclic test on a CSPW. This paper presents an investigation of the lateral performance under monotonic loading, seismic performance under cyclic loading and seismic performance under atmospheric corrosion of USW, CSW and ASW. The results show that (1) Stiffeners can improve the elastic critical buckling load, the initial stiffness and the ultimate shear resistance of CSPWs, and the effect of asymmetric diagonal stiffeners is more significant than that of cross stiffeners; (2) Stiffeners can improve the energy dissipation capacity and ductility, delay stiffness degradation and reduce the out-of-plane deformation of CSPWs, and the hysteretic performance of ASWs is obviously better than that of CSWs; and (3) Under atmospheric corrosion, stiffeners are conducive to inhibiting buckling and improving the seismic performance of CSPWs, while the seismic performance of CSWs is significantly affected by corrosion, so asymmetric diagonal stiffeners are better than cross stiffeners in improving the seismic performance of CSPWs. Meanwhile, the formula of ultimate shear resistance of corroded specimens is also fitted in this paper, which can provide design suggestions for practical engineering.

Seismic response of benchmark high-speed rail (HSR) round-ended rectangular-shaped cross-section solid (RERSCSS) concrete pier based on the shaking table tests.

High-speed rail (HSR) has recently expanded its networks globally, but its 350 km/h bridges have not yet been tested for high-level earthquakes. This study tests the typical HSR bridge on a shaking table to assess the seismic performance in high-level earthquakes such as Maximum Considered Earthquake. Based on the model similarity theory, it creates nine round-ended rectangular-shaped cross-section solid RC HSR bridge piers. It employs the orthogonal testing method to conduct experimental design considering four influential factors: aspect ratio, axial load ratio, longitudinal reinforcement rate, and volumetric stirrup ratio. Experimental research was conducted to examine the dynamic response of these piers subjected to varying seismic impacts and design parameters, and the implications of the four factors on the seismic performance of the piers were discussed. After all the earthquake circumstances, the test findings demonstrate that the concrete of the pier specimens has not cracked or spalled much. An earthquake with a peak acceleration of 0.96 g indicates that the pier body of the standard high-speed rail round-end solid pier retains its integrity and stability. The extent of the pier's earthquake damage is not immediately evident. HSR bridges' seismic design may benefit from this research, which examines the impact of dynamic characteristics, including aspect ratio, axial load ratio, and longitudinal reinforcement rate, on HSR bridge piers' seismic performance.

Mapping Relation between Rail and Bridge Deformation Considering Nonlinear Contact of Interlayer.

This paper examines the effect of structural deformation on the unit slab-type ballastless track structure of high-speed railway. The principle of stationary potential energy was used to map the relation between girder vertical deformation and rail deformation considering the effect of subgrade boundary conditions and the nonlinear contact of interlayer. The theoretical model was verified by comparing with the finite element analysis and experimental results. The theoretical model was used to analyze the effects of several key parameters on the rail deformation, such as vertical deformation amplitude, elastic modulus of the mortar layer, and vertical stiffness of the fasteners. The results show that the track slabs suffered significant disengagement, which makes the deformation of the track structure at the position of the beam joint tend to be gentle when nonlinear contact between the mortar layer and the track slabs was considered. The track slabs disengagement mainly occurs near the beam joints (the side of the deformed beam). As the deflection amplitude of the girder increases, the track deformation, the fastener forces and the disengagement length of the track slabs are obviously nonlinear. When the vertical stiffness of the fastener and/or the elastic modulus of the mortar layer increase, the fastener force and the track plate disengagement length increase monotonically and nonlinearly, which will adversely affect the life and safety of the track structure.

Modular composite building in urgent emergency engineering projects: A case study of accelerated design and construction of Wuhan Thunder God Mountain/Leishenshan hospital to COVID-19 pandemic.

Wuhan Leishenshan/Leishenshan ("Leishenshan" for short) hospital is a makeshift emergency hospital for treating patients diagnosed with the novel coronavirus-infected pneumonia (NCIP). Engineering construction uses modular composite building finished products to the greatest extent, which reduces the workload of field operations and saves a lot of time. The building information model (BIM) technology assists in design and construction work to meet rapid construction requirements. Besides, based on the unmanned aerial vehicles (UAVs) data analysis and application platform, digitization and intelligence in engineering construction are improved. Simultaneously, on-site construction and overall hoisting were carried out to achieve maximum efficiency. This article aims to take the construction of Leishenshan Hospital as an example to illustrate how to adopt BIM technology and other high-tech technology such as big data, artificial intelligence, drones, and 5G for the fast construction of the fabricated steel structure systems in emergency engineering projects.

Involvement of cationic channels in proliferation and migration of human mesenchymal stem cells.

Human mesenchymal stem cells (HMSCs) have been applied in various clinic settings. Ion channels play an important role in cellular physiology. However, the potential role of cationic channels in regulating the proliferation and migration properties of hMSCs remains to be determined. In the present study, the functional expression of ion channels in hMSCs was investigated by patch clamp. MTT assay and BrdU stainings were used to assess the proliferation of hMSCs. hMSC migration was evaluated by Transwell migration assays. The results show that sodium-, L-type calcium, potassium currents have been identified in hMSCs. TEA (K(+) channel blocker), nifedipine (Ca(2+) channel blocker) can inhibit both proliferation and migration of hMSCs. The increase of extracellular Ca(2+) concentration promoted both proliferation and migration of hMSCs. TTX, a Na(+) channel blocker, promoted cell proliferation but inhibited cell migration. Our data suggest that cationic channels (sodium, L-type calcium, potassium channels) play important roles in regulating proliferation and migration of hMSCs.