Overexpression of the PdpapERF109 gene enhances resistance of Populus davidiana×P.alba var.pyramidalis to Fusarium oxysporum infection

The key transcription factor gene PdP apE RF109 was cloned from Populus davidiana×P.alba var.pyramidalis(Pdpap),and after overexpression of P dP ap ERF109 in transformants,the gene functions in the resistance response to Fusarium oxysporum infection.Compared with the wild Pdpap,after inoculation with F.oxysporum,the physiological and biochemical characteristics,including relative fresh weight,peroxidase activity,and the percentage of electrolyte leakage showed that,after overexpression of the PdPapERF109 gene,the transformants grew well and displayed significant resistance to F.oxysporum infection.By comparing the reactive oxygen species scavenging capacity of Pdpap plants after pathogen infection,the P dPapERF109-overexpressing plants had significantly better reactive oxygen species scavenging ability than the wild plants.Comprehensive analysis of plant morphology and various physiological and biochemical parameters showed that the overexpression of the P dpapERF109 gene significantly improved the resistance of Pdpap plants to F.oxysporum root rot.Therefore,increasing the expression of the homologous ERF109 gene can be an effective strategy to increase disease resistance in hybrid poplars.

NPIPVis:A visualization system involving NBA visual analysis and integrated learning model prediction

Background Data-driven event analysis has gradually become the backbone of modern competitive sports analysis. Competitive sports data analysis tasks increasingly use computer vision and machine-learning models for intelligent data analysis. Existing sports visualization systems focus on the player–team data visualization, which is not intuitive enough for team season win–loss data and game time-series data visualization and neglects the prediction of all-star players. Methods This study used an interactive visualization system designed with parallel aggregated ordered hypergraph dynamic hypergraphs, Calliope visualization data story technology,and i Storyline narrative visualization technology to visualize the regular statistics and game time data of players and teams. NPIPVis includes dynamic hypergraphs of a team’s wins and losses and game plot narrative visualization components. In addition, an integrated learning-based all-star player prediction model, SRR-voting, which starts from the existing minority and majority samples, was proposed using the synthetic minority oversampling technique and Random Under Sampler methods to generate and eliminate samples of a certain size to balance the number of allstar and average players in the datasets. Next, a random forest algorithm was introduced to extract and construct the features of players and combined with the voting integrated model to predict the all-star players, using GridSearch CV, to optimize the hyperparameters of each model in integrated learning and then combined with five-fold cross-validation to improve the generalization ability of the model. Finally, the SHapley Additive ex Planations(SHAP) model was introduced to enhance the interpretability of the model. Results The experimental results of comparing the SRR-voting model with six common models show that the accuracy, F1-score, and recall metrics are significantly improved, which verifies the effectiveness and practicality of the SRR-voting model. Conclusions This study combines data visualization and machine learning to design a National Basketball Association data visualization system to help the general audience visualize game data and predict all-star players;this can also be extended to other sports events or related fields.

Study of the axial density/impedance gradient composite long rod hypervelocity penetration into a four-layer Q345 target

Based on the dynamic shock response of the material and structure,the hypervelocity impact processes and mechanisms of long composite rods with axial density/impedance gradients penetration into fourlayer targets were studied through experiments and numerical simulation methods.The propagation law of the shock waves,together with the structural responses of the projectiles and targets,the formation and evolution of the fragment groups formed during the processes and their distributions were described.The damage of each target plate was quantitatively analysed by comparing the results of the experiment and numerical simulation.The results showed that the axial density/impedance gradient projectiles could decrease the impact pressure to a certain extent,and the degree of damage to the target plate decreased layer by layer when the head density/impedance of the projectile was high.When the head density/impedance of the projectile was low,the degree of target damage first increased layer by layer until the projectile was completely eroded and then it decreased.The results can provide a reference for the design and application of long rods with axial composite structure for velocities ranging from 6 to 10 Ma or greater.

超高速撞击条件下靶体损伤区的数值模拟分析

超高速撞击问题中,靶体损伤区研究能够弥补部分实验中难以精确获取成坑形貌的问题,为撞击机理研究和数值模拟的校验提供重要依据.损伤区的数值模拟研究开展较少,主要原因是缺乏经过实验验证的损伤区判据.本文总结了已有的损伤区定量测量实验结果,发现对于同一种靶体,多种切片显微测试方法得到的损伤区深度比较吻合,这给损伤区分析提供了便利.基于iSALE程序模拟分析了累计塑性应变、损伤因子和峰值压力作为损伤区判断参数的适用性,认为TPS=0.1适合作为损伤判据;D=1可以作为损伤判据,但误差较大需谨慎使用;峰值压力不适合作为损伤判据.通过参数化分析发现,随着孔隙率增大和靶体强度增大,损伤区深度逐渐减小.

Influence of Assembly Parameters on Tensile Behavior of Hybrid CMC and Superalloy Bolted Joints by Progressive Damage Analysis

With the considerable applications of ceramic matrix composites(CMC) in aircraft engineering, the design of CMC bolted joint gains paramount attention because of its capacity to to improve load-bearing efficiency of aircraft key structure. In this work, a 3 D finite element model was established to predict tensile performance and failure modes of single-lap, single-bolt 2 D C/SiC composite, and superalloy joint, which considers the progressive damage behavior of 2 D woven C/SiC composites. On the basis of the developed progressive damage model, a parametric study was carried out to illustrate the effects of bolt preload and bolt-hole clearance on mechanical behaviors of the hybrid bolted joint. It was found that the increase in the value of bolt preload made the failure load grow first and then drop, and the optimum value of bolt preload 5.00 kN generated 56.47% rise in the initial failure load and 22.83% rise in the final failure load for the bolted joint in comparison with zero preload case. As the clearance increased from 0 to 2.00%, the initial and final failure loads respectively declined by 45.88% and 24.02% for 2.00% bolt-hole clearance relative to the neat-fit case. The loss in failure loads can be reduced to compressive stress concentration around the fastening hole-edge area, leading to the appearance of earlier damages by the introduction of increasing bolt hole clearance.

Review of Research Advances in CFD Techniques for the Simulation of Urban Wind Environments

Computational fluid dynamics(CFD)has become the main method for the prediction of the properties of the external wind environment in cities and other urban contexts.A review is presented of the existing literature in terms of boundary conditions,building models,computational domains,computational grids,and turbulence models.Some specific issues,such as the accuracy/computational cost ratio and the exploitation of existing empirical correlations,are also examined.

Visible Light-Mediated Cobalt and Photoredox Dual-Catalyzed Asymmetric Reductive Coupling for Axially Chiral Secondary Alcohols

Secondary alcohols bearing both axial and central chirality comprise attractive biological activity and exhibit excellent chiral induction in asymmetric reactions.However,only very limited asymmetric catalytic approaches were developed for their synthesis.We herein describe visible light-mediated cobalt-catalyzed asymmetric reductive Grignard-type addition of aryl iodides with axially prochiral biaryl dialdehydes leading to the direct construction of axially chiral secondary alcohols.Preliminary mechanistic studies indicate that efficient kinetic recognition of diastereomers might occur for axially prochiral dialdehydes to improve the stereoselectivity,which might open a new avenue for the challenging cascade construction of multiple chiral elements.This protocol features excellent enantio-and diastereoselectivity,green and mild conditions,simple operation,and broad substrate scope,providing a modular platform for the synthesis of secondary axially chiral alcohols.

DC Traction Power Supply System Based on Modular Multilevel Converter Suitable for Energy Feeding and De-icing

A novel DC traction power supply system suitable for energy feeding and de-icing is proposed in this paper for an urban rail transit catenary on the basis of the full bridge submodule (FBSM) modular multilevel converter (MMC). The FBSM-MMC is a novel type of voltage source converter (VSC) and can directly control the output DC voltage and conduct bipolar currents, thus flexibly controlling the power flow of the urban rail transit catenary. The proposed topology can overcome the inherent disadvantages of the output voltage drop in the diode rectifier units, increase the power supply distance and reduce the number of traction substations. The flexible DC technology can coordinate multiple FBSM-MMCs in a wide area and jointly complete the bidirectional control of catenary power flow during the operation of the electric locomotive, so as to realize the local consumption and optimal utilization of the recovered braking energy of the train. In addition, the FBSM-MMCs can also adjust the output current when the locomotive is out of service to prevent the catenary from icing in winter. The working modes of the proposed topology are illustrated in detail and the control strategy is specially designed for normal locomotive operations and catenary de-icing. Simulation cases conducted by PSCAD/EMTDC validate the proposed topology and its control strategy.

Visible light-mediated NHCs and photoredox co-catalyzed radical 1,2-dicarbonylation of alkenes for 1,4-diketones

Alkenes are ubiquitous,and the difunctionalization of alkenes represents one of the most practical approaches for the construction of value-added compounds.Dicarbonylation of alkenes provides direct access to value-added 1,4-dicarbonyl compounds.However,selectivity control for unsymmetric 1,2-dicarbonylation is of great challenge.We herein describe NHCs and photocatalysis co-catalyzed three-component radical 1,2-dicarbonylation of alkenes by distinguishing two carbonyl groups,providing structurally diversified 1,4-diketones.Distinct properties of acyl radical and NHCs-stabilized ketyl radical contributed to selectivity control.Acyl radicals are rapidly added to alkenes delivering alkyl radicals,which undergo subsequent radicalradical cross-coupling with NHCs-stabilized ketyl-type radicals,affording 1,2-dicarbonylation products.This transformation features mild reaction conditions,broad substrate scope,and excellent selectivity,providing a general and practical approach for the dicarbonylation of olefins.

Energy-Dissipative Hydrogels:A Promising Material for Tissue Regeneration

Hydrogels are promising candidates for mimicking native extracellular matrix(ECM)and are therefore widely adopted as scaffolds in tissue engineering.However,conventional hydrogels composed of static networks are prone to permanent structural damages and lack the ability to provide the time-dependent mechanical cues,which are essential for cell development,ECM remodeling,and tissue regeneration.The recent substantial development in the structurally dynamic hydrogels with energy-dissipative ability has demonstrated the unique capability of such viscoelastic hydrogels to withstand extreme biomechanical loads and regulate cellular behaviors not present in classical hydrogels.This review starts with the general design principles for energy-dissipative hydrogels,followed by recent advancements in fabrication approaches for energy-dissipative hydrogels.We then highlight some applications of energy-dissipative hydrogels in tissue engineering,including bone and cartilage regeneration,vessel regeneration,nerve regeneration,and wound healing.Finally,we discuss about the key current challenges and future development of energy-dissipative hydrogels for biomedical applications.

Synthesis and Antibacterial Properties of ZIF-8/Ag-Modified Titanium Alloy

The loosening of implant due to bacterial infection brings great difficulties to the implantation of bionic titanium devices.In this study,the Zeolitic Imidazolate Framework 8(ZIF-8)and silver ions were added to the surface of titanium alloy to obtain a uniform coating,which has nice biological activity and antibacterial property.The material structure characterizations,such as X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),proved that titanium is successfully modified with ZIF-8 and silver ions.It has micro-and nano-level characteristics,rough porous morphology,and excellent apatite inducing ability.The water contact angle experiment shows that the addition of ZIF-8 greatly increases the hydrophilicity of material,which provides conditions for the attachment of osteoblasts.The polarization curve obtained from the electrochemical test proves that the addition of ZIF-8 coating improves the corrosion resistance of titanium.The release of silver ion has a strong growth inhibitory effect on E.coli,and exhibits excellent antibacterial properties.Therefore,the preparation of ZIF-8/Ag coatings on 3D printed titanium provides a new option for the development of orthopedic implants.

Construction of Zn-incorporated Micro/Nano Hierarchical Structure Coatings on Tantalum

Tantalum(Ta)alloys have been widely used as bone repair materials duc to their excellent biocompatibility.In present work,zinc(Zn)incorporated ceramic coatings with micro/nano hierarchical structure were successfully fabricated on Ta by micro-arc oxidation and hydrothermal treatment.The content of Zn ions is about(1.35士0.3)wt%.Cortex-like rough morphology(Ra:1.504μm)with irregular vermiform slots can be clearly observed on the surface of Ta.More importantly,the coatings resembling the structure of natural bone can release Zn,Ca,and P ions in a controlled and sustained manner.The corrosion resistance ofTa is greatly improved after functionalized with ceramic coatings,confirming by potentiodynamic polarization tests.The bonding strength between the coatings and substrates can be up to 18.9 N.Furthermore,the surface of MAOs-HT@Ta is covered by bonelike apatite after immersed in Simulated Body Fluid(SBF)for three weeks,showing excellently bioactivity.These results suggest that the innovative Zn-incorporated micro/nano hierarchical coatings on Ta may be used as promising candidates for orthopedic implants.

The bipolar kicker power supply principle prototype for the booster ring of HIAF

Background The kicker power supply is one of the key devices to achieve fast extraction for the booster ring(BRing)of high intensity heavy ion accelerator facility.For the expected high beam intensity in the BRing,a beam dump is requested for an emergency case.Therefore,a bipolar kicker power supply is required to extract bunched beams to the regular beamline and the beam dump.Purpose The purpose of this paper is to design and test a bipolar kicker power supply principle prototype.Methods For this purpose,a solid-state Marx generator circuit based on pulse forming network with insulated gate bipolar transistors is applied to the bipolar kicker power supply principle prototype.Results The experimental results show that the principle prototype has the ability to produce a bipolar extraction current,and the polarity can be arbitrarily selected.Besides,a flat-top duration of the extraction current adjusting from 0 to 1.23μs has been accomplished.Conclusions The output performance of the principle prototype satisfies the design requirements and verifies the feasibility of the design.