Based on bed form experiments in a large‐scale flume, we demonstrate that the rate of development of wave ripples on a mixed sand‐clay bed under regular waves is significantly lower than on a pure‐sand bed, even at clay fractions as low as 4.2%, and that this rate of development decreases exponentially from 4.2% to 7.4% clay. These experiments also showed that, despite the slow growth of the bed forms in the mixed sand‐clay, the equilibrium length and height of the wave ripples were independent of the initial bed clay fraction. Given that the ripple crests were composed of pure sand at the end of all the experiments that started with well‐mixed sand‐clay, it is inferred that the clay was removed from the bed during the development of the wave ripples through winnowing into the water column, and possibly also by sieving into the subsurface, where the final clay fractions were found to be higher than the initial clay fractions. These clay removal processes are interpreted to have facilitated the wave ripples to reach equilibrium lengths and heights that are similar to those in pure sand. Clay‐carrying pore flow initiated by pressure gradients between the wave ripple troughs and crests might also have contributed to the accumulation of clay in the sediment below the wave ripples. The formation of the clay‐enriched “armoring” layer in the substrate is likely to further reduce erosion rates and could influence the dispersion of nutrients and pollutants in coastal seas.

We used accelerator mass spectrometry (AMS) 14C‐dated sediments of the Holocene basal supratidal flat to upper tidal flat facies in 11 cores on the southern Yangtze delta plain to reconstruct relative sea levels of 8.5–8.0 cal ka BP. Three cores were further AMS 14C dated and used to examine the evolution of sedimentary geomorphological environments in response to the rapid sea‐level rise during the early to mid‐Holocene. Results demonstrate relative sea‐level rise of around 30 mm a−1 from 8.5 to 8.3 cal ka BP and around 10 mm a−1 from 8.3 to 8.0 cal ka BP. Retrogradation from supratidal to lower tidal flat environments occurred in response to the rapid sea‐level rise at 8.5–8.3 cal ka BP, and aggradation from middle to upper tidal flat occurred at 8.3–7.9 cal ka BP. Further retreat of the tidal flat at 7.9–7.2 cal ka BP implies a mean sea‐level rise rate exceeding 5 mm a−1 at this time. We suggest that the rapid relative sea‐level rise during 8.3–8.5 cal ka BP and subsequent slower rise caused drastic changes in the coastal zone and that these changes are key phenomena for understanding the coastal response to future sea‐level rise.

RESCUE BT Trial Investigators E ndovascular treatment has been shown to significantly increase the reperfusion rate and improve the functional outcomes of patients with acute ischemic stroke due to large vessel occlusion. [1][2][3][4] However, endovascular thrombectomy has historically failed to yield successful reperfusion in approximately 30% of patients. 5 Unsuccessful reperfusion likely arises in part from mechanical thrombectomy devices causing traumatic damage to the vascular endothelium with subendothelial matrix exposure, leading to platelet activation, adhesion, and aggregation and potentially resulting in reocclusion and thromboembolic complications. 6,7 Tirofiban, a highly selective nonpeptide platelet glycoprotein IIb/IIIa inhibitor with a relatively short half-life that can reversibly prevent platelet aggregation, has been proven to reduce the risk of thrombotic complications during percutaneous coronary intervention. [8][9][10] Given the benefit of treatment of acute coronary syndromes, a growing number of studies have evaluated tirofiban as an adjunctive treatment in patients with large vessel occlusion ischemic stroke IMPORTANCE Tirofiban is a highly selective nonpeptide antagonist of glycoprotein IIb/IIIa receptor, which reversibly inhibits platelet aggregation. It remains uncertain whether intravenous tirofiban is effective to improve functional outcomes for patients with large vessel occlusion ischemic stroke undergoing endovascular thrombectomy.OBJECTIVE To assess the efficacy and adverse events of intravenous tirofiban before endovascular thrombectomy for acute ischemic stroke secondary to large vessel occlusion.DESIGN, SETTING, AND PARTICIPANTS This investigator-initiated, randomized, double-blind, placebo-controlled trial was implemented at 55 hospitals in China, enrolling 948 patients with stroke and proximal intracranial large vessel occlusion presenting within 24 hours of time last known well.

Measurements of magnetic properties, total organic carbon (TOC) and total sulphur (TS) were performed on recent tidal flat sediments from the Feng-Xian (FX) and Bei-Bu-Gang (BBG) areas of the Yangtze coast and on Holocene tidal flat sediments from core SL67 from the southern Yangtze delta plain, China. The results indicate that greigite has likely formed in the recent upper and middle tidal flat sediments of cores FX and BBG, which are enriched in TOC and TS. Greigite is also present in association with pyrite in the early to middle Holocene saltmarsh and tidal flat sediments of SL67. The abundance of greigite in the early Holocene basal saltmarsh sediments of core SL67, along with the extremely low values of TS/TOC, suggest the presence of either a limited sulphate supply from seawater or a major terrestrial source of organic matter that decomposed slowly. The presence of greigite in mid-Holocene lower tidal flat sediments that contained low amounts of TOC indicates an upward diffusion of CH4 and H2S from the underlying upper tidal flat sediments. A comparison between the sediments of core SL67 and those of the modern tidal flat suggests that early diagenesis (including selective dissolution and pyritisation) continued after the sediments were buried during the Holocene, resulting in the depletion of soil-derived superparamagnetic (SP) particles and the enhanced magnetic properties because of authigenic greigite. However, antiferromagnetic magnetic minerals have not been altered by early diagenesis. Thus, magnetic parameter hard isothermal remanent magnetisation (HIRM) which preserved the primary magnetic signals reflects fluctuations in the detrital mineral input to the core site and records a two-stage 8.2 ka cooling event.

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