Shear Behaviors of Steel-Plate Connections for Timber-Concrete Composite Beams with Prefabricated Concrete Slabs

To promote the development of timber-concrete composite(TCC)structures,it is necessary to propose the assembly-type connections with high assembly efficiency and shear performances.This article presented the experimental results of the innovative steel-plate connections for TCC beams using prefabricated concrete slabs.The steel-plate connections consisted of the screws and the steel-plates.The steel-plates were partly embedded in the concrete slabs.The concrete slabs and the timber beams were connected by screws through the steel-plates.The parameters researched in this article included screw number,angle steel as the reinforcement for anchoring,and shallow notches on the timber surface to restrict the slip of the steel-plates.Experimental results were discussed in terms of failure modes,ultimate bearing capacities,and slip moduli.It was found that increasing the number of screws could lead to the obvious improvement on the ultimate bearing capacities and the slip moduli at the ultimate state;and the angle steel as the reinforcement showed the slight influence on the ultimate bearing capacities and the slip moduli.The application of the shallow notch can greatly improve the ultimate bearing capacities and the slip moduli.The calculation models for the ultimate bearing capacities and the slip moduli of the steel-plate connections with and without shallow notches were proposed,which showed good accuracy compared with the experimental results.

Effects of Two Potential Allelochemicals on the Photosystem II of Nitzschia closterium and Monostroma nitidum

In aquaculture,high-density seaweed farming brings higher economic benefits but also increases outbreaks of diatom felt.The effective control of diatom felt in high-density seaweed farming has always been a research hotspot.This study selected two potential allelochemicals 2-hydroxycinnamic acid and quinic acid to explore their effects on a diatom Nitzschia closterium and an economic seaweed Monostroma nitidum.The results showed that 2-hydroxycinnamic acid had better inhibitory effects than quinic acid on the growth,pigment content and photosynthetic efficiency of N.closterium.Their half-maximal inhibitory concentrations at 120 h(IC_(50–120 h))were 0.9000 and 1.278 mM,respectively.Additionally,these allelochemicals had limited inhibitory effects on the growth,pigment content and photosynthetic efficiency of M.nitidum before 24 h.To further explore the allelopathic effect of these chemicals,this study focused on the photosystem II energy fluxes of N.closterium.It was found that 3 mM 2-hydroxycinnamic acid could destroy the whole photosynthetic system by devastating the PSII reaction centre(RC)before 24 h;however,the same concentration of quinic acid could only down-regulate the electron transport efficiency by changing the effective antenna size of an active RC and downregulating the PSII reaction centre density.These experimental results are expected to provide a new strategy to control diatom felt blooms on the high-density seaweed farming areas.

Unveiling the promotion of accelerated water dissociation kinetics on the hydrogen evolution catalysis of NiMoO_(4) nanorods

Nickel molybdate(NiMoO_(4))attracts superior hydrogen desorption behavior but noticeably poor for efficiently driving the hydrogen evolution reaction(HER)in alkaline media due to the sluggish water dissociation step.Herein,we successfully accelerate the water dissociation kinetics of NiMoO_(4)for prominent HER catalytic properties via simultaneous in situ interfacial engineering with molybdenum dioxide(MoO_(2))and doping with phosphorus(P).The as-synthesized P-doped NiMoO_(4)/MoO_(2)heterostructure nanorods exhibit outstanding HER performance with an extraordinary low overpotential of-23 m V at a current density of 10 m A cm^(-2),which is highly comparable to the performance of the state-of-art Pt/C coated on nickel foam(NF)catalyst.The density functional theory(DFT)analysis reveals the enhanced performance is attributed to the formation of MoO_(2)during the in situ epitaxial growth that substantially reduces the energy barrier of the Volmer pathway,and the introduction of P that provides efficient hydrogen desorption of Ni MoO_(2).This present work creates valuable insight into the utilization of interfacial and doping systems for hydrogen evolution catalysis and beyond.

SAGES南山1米大视场望远镜g、r、i波段测光数据流量定标

均匀且精确的流量定标是大视场测光巡天数据处理的难点和核心所在.本文借助LAMOST(Large Sky Area Multi-Object Fiber Spectroscopic Telescope)DR7光谱数据、修正后的Gaia EDR3测光数据和Gaia测光丰度数据,使用基于光谱的SCR(Stellar Color Regression)方法和基于测光的SCR方法(SCR′方法)构建了南山1米大视场望远镜g、r、i波段精度约为10~20毫星等的260多万颗标准星,进而对SAGES(Stellar Abundance and Galactic Evolution Survey)南山1米望远镜拍摄的约4254平方度天区的测光数据进行了相对流量定标.在此过程中,我们仔细考虑了定标零点随不同图像(时间)、探测器不同通道及星像在探测器不同位置的变化.基于修正后的Pan-STARRS(PS1)DR1测光数据,进行了绝对流量定标,并给出了南山g、r、i波段定标后的星等与PS1星等之间的相互转换关系.基于相邻图之间的共同源对定标精度进行了内部一致性检验,发现3个波段的定标精度均约为2.0毫星等.同时,我们还对定标精度做了外部检验,使用Gaia DR3无缝光谱合成的PS1星等,发现定标均匀性在1.3°分辨本领下分别为2.4、2.3和0.9毫星等.此外,本文还讨论了恒星平场和探测器通道间相对增益随时间的变化.

Tailoring microstructure and electrical transportation through tensile stress in Bi_(2)Te_(3) thermoelectric fibers

Bismuth telluride(Bi_(2)Te_(3))has attracted much attention in the field of thermoelectrics since it is one kind of commercial room-temperature thermoelectric material.Herein three kinds of Bi_(2)Te_(3) thermoelectric fibers with internal tensile stress are fabricated utilizing an optical fiber template method.The effects of internal stress on the microstructure and the electrical transportation of Bi_(2)Te_(3) thermoelectric fibers are investigated.The Bi_(2)Te_(3) cores in the fibers are highly crystalline and possess a tensile nanosheet structure with preferential orientation as evidenced by X-ray diffraction and Raman studies.Tensile stress can enhance electrical properties of the fibers.And a paper cup generator covered with 20 pieces of optimized fibers provides a μW-level output power.It is inferred that tensile stress tuning can be an effective tool for the material optimization of thermoelectric performance.