A novel dealloying strategy for fabricating nanoporous Ag via ζ'-AgGa alloy.

A mild strategy for fabricating nanoporous silver (np-Ag) pieces was reported via preparation of Ag-Ga alloys in relatively low temperature and subsequent electrochemical dealloying in nitric acid (HNO3) aqueous solution. After selectively etching Ga out of the Ag-Ga alloy, a typical three-dimensional (3D) bicontinuous nanoporous structure with a pore size of ∼67.21-159.33 nm was observed. A series of studies have shown that the addition of sodium dodecyl sulfate (SDS) results in minimum pore size. The coarsen exponent (n) is 1.61, and the activation energy was calculated to be 27.04 kJ mol-1. Theζ'-AgGa alloy prepared at low temperature can be used as the precursor for the preparation of fine np-Ags, and this method provides a new strategy for the industrial production of dealloyed np-Ag.

Untangling impacts of global warming and Interdecadal Pacific Oscillation on long-term variability of North Pacific tropical cyclone track density.

How much the observed long-term variability of tropical cyclone (TC) activity is due to anthropogenic global warming (GW) or internal climate variability remains unclear, limiting the confidence in projected future change in TC activity. Here, the relative contributions of GW and the Interdecadal Pacific Oscillation (IPO) to the long-term variability of TC track density (TCTD) over the North Pacific (NP) are quantified on the basis of statistical analyses and climate model simulations. Results show that historical GW mainly reduced (increased) TCTD over the western (eastern) NP, while the positive (negative) IPO corresponds to a NP basin-wide increase (decrease) in TCTD except in some coastal regions. The IPO has a much greater impact on TCTD over the western NP than GW, while the IPO and GW impacts are about equal over the eastern NP during 1960-2019. These findings have important implications for projecting future TC activity over the NP.

Global warming hiatus contributed to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia.

The recent global warming hiatus (GWH) was characterized by a La Niña-like cooling in the tropical Eastern Pacific accompanied with the Indian Ocean and the tropical Atlantic Ocean warming. Here we show that the recent GWH contributed significantly to the increased occurrence of intense tropical cyclones in the coastal regions along East Asia since 1998. The GWH associated sea surface temperature anomalies triggered a pair of anomalous cyclonic and anticyclonic circulations and equatorial easterly anomalies over the Northwest Pacific, which favored TC genesis and intensification over the western Northwest Pacific but suppressed TC genesis and intensification over the southeastern Northwest Pacific due to increased vertical wind shear and anticyclonic circulation anomalies. Results from atmospheric general circulation model experiments demonstrate that the Pacific La Niña-like cooling dominated the Indian Ocean and the tropical Atlantic Ocean warming in contributing to the observed GWH-related anomalous atmospheric circulation over the Northwest Pacific.