Succimer

Volatile sulfur compounds, such as dimethyl sulfide (DMS), carbonyl sulfide (OCS), and carbon disulfide (CS₂), significantly influence atmospheric chemistry and climate change. Despite the oceans being an important source of these sulfides, the limited understanding of their biogeochemical cycles in seawater introduces considerable uncertainties in quantifying their oceanic emissions and assessing atmospheric OCS budgets. To address this issue, we conducted a comprehensive field survey in the tropical eastern Indian Ocean (EIO) to examine the spatial distributions, source-sink dynamics, and sea-air exchange fluxes of marine DMS, OCS, and CS₂. Our study indicates that nutrients, organic matter, and freshwater input from terrestrial runoff significantly affect most of the source-sink processes of these sulfides in the Bay of Bengal and even the tropical EIO. The resulting sulfide accumulation in seawater combined with high wind speeds establishes the tropical EIO as a considerable direct and indirect atmospheric OCS source. These insights underscore the potentially critical role of marine environments influenced by runoff in contributing to the atmospheric OCS budget. However, by integrating these results with previous field surveys, we believe that actual OCS emissions from tropical oceans exceed some bottom-up box-model simulations, yet fall significantly below those predicted by top-down models, still insufficient to bridge the atmospheric OCS source gap. Our detailed examination of source-sink dynamics offers deeper insights into the marine sulfur cycle and has potential implications for refining future box-models, thus mitigating uncertainties in estimating marine sulfur emissions.

Endoscopic submucosal dissection (ESD) is an effective treatment for polyps and early gastrointestinal cancers, but requires a high level of operator skill. Injecting submucosal materials (SIM) helps create a fluid cushion between the mucosal and muscular layers, making the procedure easier and reducing associated risks. However, SIMs commonly used in current clinical practice tend to spread quickly and fail to provide long-lasting submucosal fluid cushions (SFC). Thus, there is a critical need for a material that is easy to inject while also maintaining a durable barrier. We prepared succinylated hydroxybutyl chitosan (HBC-SA) by adding succinic anhydride (SA) to hydroxybutyl chitosan (HBC). The hydrogel had excellent temperature-sensitive properties and was able to be injected via an endoscopic injection needle even after gel formation. In vitro and in vivo studies showed that it has satisfactory biocompatibility. Functional experiments showed that the submucosal lifting properties of this hydrogel were significantly better than that of normal saline (NS) and sodium hyaluronate (SH), two commonly used clinical materials. In addition, the hydrogel possessed excellent hemostatic properties. Based on these results, HBC-SA is a promising candidate for submucosal injection during ESD.