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Floods are common natural disasters in Asia. Flood datasets from 48 countries in Asia were collected to investigate the spatiotemporal distribution and influencing factors, using the Mann–Kendall trend test and the Spearman’s rank correlation. These results show that flood occurrences and damages increased significantly in Asia, with the mortality rates and deaths decreasing. Southern and Eastern Asia are flood vulnerable regions, with Central Asia being the least flood-occurrence region, and China and India are also flood-prone countries with a largest population and land area in Asia. Least flood disasters occurred in Bahrain, Cyprus, Brunei Darussalam and Singapore, with a smaller population and land area. The spatial disparities of flood disasters were positively influenced by population and land area, and negatively influenced by urbanization rate and per capita GDP. The largest proportion of flood disasters were discovered in riverine floods, followed by flash floods, with coastal floods being the least. The highest and second-highest mortality rates were observed in flash floods and coastal floods, which showed decreasing trends, and the mortality rate of riverine floods was the lowest, with an increasing trend. The rain was the main triggering origin of floods, and tropical cyclone contributed to the second, followed by snowmelt, convective storms, and dam-break flows. This analysis can help to provide a useful insight into the formulation of flood risk maps, disaster mitigation measures and emergency management.

Street inlets play a key role in intercepting surface runoff into underground drainage systems, which can reduce the hazard degree during urban flood events. An accurate calculation of the discharge capacity of street inlets is vitally important in numerically modelling urban floods and managing flood resilience. A series of laboratory experiments were combined with a theoretical analysis in this study to investigate the conveyance characteristics of a typical street grate inlet. A large-scale laboratory platform was constructed, consisting of an upper-layer model street and an underground measuring system installed with a V-notch weir structure. A model street inlet was used to connect the upper and underground layers, which had a complete drainage structure including: an inlet grate, a drain box, and a connection tube. A total of 78 experimental runs were conducted using this laboratory platform, and the discharges intercepted by the grate inlet were measured for a range of incoming water depths and flow velocities, where the approaching Froude number varied from 0.05 to 0.89. These experimental results showed that the drainage pattern of the street inlet was converted from weir flow to orifice flow after the drain box was fully pressurized. In addition, a power function was derived between the relative drainage velocity through the inlet and the approaching Froude number, based on the method of dimensional analysis, and a unified formula was proposed to calculate the discharge capacity of street inlets. The corresponding coefficients in the formula were calibrated using the laboratory measurements. The unified discharge capacity formula was verified using other experimental results obtained from previous studies, and the results indicated that the calculated results using the unified formula agreed well with these measurements, with the regression coefficients of R2 > 0.90. Therefore, the unified formula for discharge capacity of street inlets obtained from the study reported herein has a high predictive accuracy, which can be used in numerical modelling and risk management of urban floods.

The discovery of photo-assisted diazonium activation toward gold(I) oxidation greatly extended the scope of gold redox catalysis by avoiding the use of a strong oxidant. Some practical issues that limit the application of this new type of chemistry are the relative low efficiency (long reaction time and low conversion) and the strict reaction condition control that is necessary (degassing and inert reaction environment). Herein, an alternative photo-free condition has been developed through Lewis base induced diazonium activation. With this method, an unreactive Au(I) catalyst was used in combination with Na2CO3 and diazonium salts to produce a Au(III) intermediate. The efficient activation of various substrates, including alkyne, alkene and allene was achieved, followed by rapid Au(III) reductive elimination, which yielded the C-C coupling products with good to excellent yields. Relative to the previously reported photo-activation method, our approach offered greater efficiency and versatility through faster reaction rates and broader reaction scope. Challenging substrates such as electron rich/neutral allenes, which could not be activated under the photo-initiation conditions (

An efficient synthesis of substituted cyclopentenes through gold/gallium-catalyzed annulation of 1,3-dicarbonyl compounds and cyclopropylacetylenes is achieved. This tandem reaction consists of a gold-catalyzed Nakamura reaction, a catalytic dienol–enone tautomerization, and a gallium-catalyzed vinylcyclopropane (VCP) rearrangement.

Fluorescence active fused-triazole was developed as a ligand in gold(I) cation coordination. The coordination ability was evaluated using NMR and fluorescence emission. Our previously reported N-2-aryl-triazoles, though gave good emission, could not form stable complexes with gold cations. A new N-fused-triazole (NFT) derivative was prepared and the ligand indicated good fluorescence emission, and formed strong coordination with gold cations. Both ligand and complex were characterized by X-ray crystallography. Fluorescence properties of various gold complexes (with different primary ligands) were evaluated, which suggested the feasibility of using fluorescence emission as potential tools for future mechanistic investigation.

Gold-catalyzed oxidative cross-coupling of alkynes to unsymmetrical diynes has been achieved for the first time. A N,N-ligand (1,10-Phen) and PhI(OAc)2 were identified as crucial factors to promote this transformation, giving the desired cross-coupled conjugated diynes in excellent heteroselectivity (>10:1), in good to excellent yields, and with large substrate tolerability.

An unexpected ligand effect was discovered in the silver(I)-catalyzed alkyne activation. For both aldehyde-alkyne-amine (A3) condensation and intermolecular alkyne hydroamination, the type B complex (P:Ag=1:1) effectively promoted the reaction, while no reaction occurred with either no ligand or excess ligands under the identical conditions.