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Fatigue vehicle load is essential for fatigue analysis, whose accuracy is directly associated with fatigue design. With the development of society, traditional fatigue vehicle load may fail to reflect modern traffic conditions, especially for transportation hubs in developed areas. Based on traffic flow data of a long-span steel box girder bridge, statistical analysis is performed and the two types of standard vehicle load are equivalent. Further, fatigue characteristics and fatigue life of two types of welded connection are compared based on the equivalent structural stress method. As a result, 2-axle vehicle takes the largest proportion, and the overload ratio of a 6-axle vehicle is the highest. Compared with fatigue vehicle load III, there should be a correction coefficient 1.89 and 2.30 for equivalent vehicle load based on average traffic flow and heavy lane traffic flow, respectively. For a single-side welded connection and a double-side welded connection, the equivalent structural stress will increase by 81.0%–131.2% for positions of concern when considering heavy lane traffic flow, which is about 21% higher than results considering average traffic flow. In addition, the fatigue life of these concerned positions will encounter a dramatic decrease. Fatigue life of the most unfavorable position is 492.4 years and cracks will occur in 90.0 years based on fatigue vehicle load III. However, it will decrease to 42.3 years and 7.7 years, respectively, when considering the traffic flow of the heavy lane. [ABSTRACT FROM AUTHOR]

An easy prepared probe, BHMMP, was designed and synthesized, which displayed a significant fluorescence enhancement (over 38-fold) and obvious color change in the recognition of Al3+. The binding ratio of probe BHMMP to Al3+ was determined as 1:1, according to Job plot. The binding mechanism was fully clarified by the experiments, such as FT-IR spectrum, ESI–MS analysis, and 1H NMR titration. A DFT study further confirmed the binding mode of BHMMP to Al3+. The limit of detection (LOD) for Al3+ was determined as low as 0.70 µM, based on the fluorescence titration of BHMMP. Moreover, the results from real sample experiments, including real water samples, test papers, and cell images, well-demonstrated that BHMMP was capable of sensing Al3+ in environmental and biological systems. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are increasingly becoming an important choice for developing robust and efficient electrocatalysts; therefore, exploring the relationship between the structure, catalytic activity, and stability of MOFs is of great significance. MOFs 1 - 3 with different spatial configurations are designed and synthesized based on linear pyridine ligands, tetragonal carboxylic acid ligands, and triangular carboxylic acid ligands, while MOF 4 displays a three-dimensional (3D) supramolecule assembled through a mixed-ligand strategy. Compared with MOFs 1 - 3 , MOF 4 has the lowest overpotential of 106 mV (at 10 mA·cm -2 ) and a Tafel slope of 80.9 mV·dec -1 , as well as sturdy long-term stability in the process of oxygen evolution reaction (OER). The presence of dense metal clusters and μ 3 -O promotes the optimal catalytic performance of MOF 4 . Density functional theory (DFT) calculations of MOF 4 demonstrate that the process from O* to OOH* is the rate-determining step. This investigation further reveals the relationship between MOF structural composition and electrocatalytic OER performance and provides an effective strategy for the assembly of MOF-based electrocatalysts.

Converting CO 2 to valuable chemicals and fuels is a viable method to establish a carbon-neutral energy cycle in the environment. Metal-organic frameworks (MOFs), characterized by dispersed active sites, high porosity, etc., have displayed a great application prospect in the electrochemical/chemical CO 2 reduction reaction (CO 2 RR) process. Herein, we proposed a one-step production to establish a series of pillar-layered porous MOFs, [Co 2 (L)(bimb)] n (MOF 1 ) and [Co 4 (L) 2 (bidpe) 2 ] n (MOF 2 ) [H 4 L = 5'-(4-carboxyphenyl)-(1,1':2',1″-terphenyl)-4,4',4″-tricarboxylic, bimb = 1,4-bis(imidazol-1-yl)-butane, bidpe = 4'-bis(imidazolyl) diphenyl ether], for preferential conversion of CO 2 via ligand adjustment and increase of active sites' density. According to single-crystal X-ray diffraction studies, [Co 2 (L)(bimb)] n exhibits pillar-layered binuclear 3D frameworks with a 2,4,6-linked 3-nodes new topology structure, while [Co 4 (L) 2 (bidpe) 2 ] n displays pillar-layered tetranuclear interspersed networks with a 4,6-linked 2-nodes fsc topology structure through a ligand adjustment strategy. Meanwhile, the pillar-layered structure of the MOFs with abundant active sites is conducive to mass diffusion and benefits the conversion of CO 2 . MOFs 1 - 2 exhibit good electrocatalytic activity for CO 2 RR in 0.5 M KHCO 3 solution. Especially, the current density of MOF 2 generated at -0.90 V (vs. RHE) reaches -81.6 mA·cm -2 , which is 3.1 times higher than that under an Ar atmosphere. In addition, MOFs 1 - 2 can be used as a heterogeneous catalyst for chemical conversion of CO 2 . The results are expected to provide inspiration for rational design to develop stable and high-efficiency MOF-based electrocatalysts for CO 2 RR.