Effects of O, S, and P in transition-metal compounds on the adsorption and catalytic ability of sulfur cathodes in lithium-sulfur batteries.

Transition-metal compounds (TMCs) have recently become promising candidates as lithium-sulfur (Li-S) battery cathode materials because they have unique adsorption and catalytic properties. However, the relationship between the anionic species and performance has not been sufficiently revealed. Herein, using FeCoNiX (X = O, S, and P) compounds as examples, we systematically studied the effects of the anion composition of FeCoNiX compounds on the adsorption and catalytic abilities of sulfur cathodes in Li-S batteries. Adsorption tests and density functional theory calculations showed that the adsorption ability toward lithium polysulfides follows the order: FeCoNiP > FeCoNiO > FeCoNiS, while in situ ultraviolet-visible spectroscopy and cyclic voltammetry revealed that the catalytic ability for lithium polysulfide conversion follows the order: FeCoNiP > FeCoNiS > FeCoNiO. These results indicate that FeCoNiP is an excellent polysulfide immobilizer and catalyst that restricts shuttling and improves reaction kinetics. Electrochemical tests further demonstrated that the FeCoNiP cathode delivered superior cycling performance to FeCoNiO or FeCoNiS. In addition, the battery performance order is consistent with that of catalytic ability, which suggests that catalytic ability plays a key influencing role in batteries. This study provides new insight into the use of O-, S-, and P-doped TMCs as functional sulfur carriers.

[Pattern evolution and impact factor of Jiuduansha Wetland at the Yangtze Estuary during 1989-2020]. / 1989­2020å¹´é•¿æ±Ÿå£ä¹æ®µæ²™æ¹¿åœ°æ ¼å±€æ¼”å˜åŠå½±å“å› ç´ .

Affected by the changes of drainage basin and marine environment and human activities, estuarine wetland is fragile, sensitive, and complex in evolution. Jiuduansha Wetland is the largest estuarine shoal wetland in the Yangtze Estuary, and is undergoing rapid changes due to the reduction of sediment inputs and the invasion of alien species Spartina alterniflora. In this study, the changes of Jiuduansha Wetland from 1989 to 2020 were analyzed through remote sensing interpretation, field investigation, and topographic data analysis. The impacts of watershed sediment reduction and S. alterniflora invasion on Jiuduansha Wetland were analyzed based on the hydrological data of Datong station and the invasion history of S. alterniflora. The results showed that the total area of Jiuduansha Wetland (above -5 m) first increased and then decreased since 1991, reaching its maximum in 2005 (421.16 km2). The area of tidal flat wetland (above 0 m) and wetland vegetation increased continuously from 1989 to 2020, with 1.5 times and 47.1 times increases, respectively. The decreases of sediment supply led to a decrease in the total area of Jiuduansha Wetland (above -5 m) and a decrease growth rate of tidal flat wetland area above 0 m and vege-tation area. The invasive species S. alterniflora had expanded rapidly, occupied the space of native species, and became the dominant species in Jiuduansha Wetland since it was introduced in 1997. Sediment reduction and S. alterniflora invasion had led to the rapid changes of Jiuduansha Wetland structure. In order to avoid the degradation of ecological service, wetland protection and restoration should be taken to maintain the stability and health of Jiu-duansha Wetland.

Albumin-assembled copper-bismuth bimetallic sulfide bioactive nanosphere as an amplifier of oxidative stress for enhanced radio-chemodynamic combination therapy.

The tumor microenvironment with overexpressed hydrogen peroxide (H2O2) and reinforced antioxidative system (glutathione, GSH) becomes a double-edged sword for the accessibility of nano-therapy. Since reactive oxygen species (ROS) are easily quenched by the developed antioxidative network, ROS-based treatments such as chemodynamic therapy (CDT) and radiotherapy (RT) for killing cancer cells are severely attenuated. To overcome such limitations, a bioactive nanosphere system is developed to regulate intracellular oxidative stress for enhanced radio-chemodynamic combination therapy by using bovine serum albumin (BSA) based bioactive nanospheres that are BSA assembled with in situ generated copper-bismuth sulfide nanodots and diallyl trisulfide (DATS). The copper-bismuth sulfide nanodots react with H2O2 to produce •OH and release Cu2+. Then, the Cu2+ further depletes GSH to generate Cu+ for more •OH generation in the way of Fenton-like reaction. Such a cascade reaction can initiate •OH generation and GSH consumption to realize CDT. The elevation of ROS triggered by the DATS from BBCD nanospheres further augments the breaking of redox balance for the increased oxidative stress in 4T1 cells. With the sensitization of increased oxidative stress and high Z element Bi, an enhanced radio-chemodynamic combination therapy is achieved. The current work provides an enhanced radio-chemodynamic combination treatment for the majority of solid tumors by using the co-assembled bioactive nanospheres as an amplifier of oxidative stress.

Precise Fabrication of Porous Microspheres by Iso-Density Emulsion Combined with Microfluidics.

Polymer porous microspheres with large specific surface areas and good fluidity have promising important applications in the biomedical field. However, controllable fabrication of porous microspheres with precise size, morphology, and pore structure is still a challenge, and phase separation caused by the instability of the emulsion is the main factor affecting the precise preparation of porous microspheres. Herein, a method combining the iso-density emulsion (IDE) template and microfluidics was proposed to realize the controllable preparation of polymer porous microspheres. The IDE exhibited excellent stability with minimal phase separation within 4 h, thus showing potential advantages in the large-scale preparation of porous microspheres. With the IDE template combined microfluidics technique and the use of a customized amphoteric copolymer, PEG-b-polycaprolactone, polycaprolactone (PCL) porous microspheres with porosity higher than 90% were successfully prepared. Afterwards, the main factors, including polymer concentration, water-oil ratio and homogenization time were investigated to regulate the pore structure of microspheres, and microspheres with different pore sizes (1-30 µm) were obtained. PCL porous microspheres exhibited comparable cell viability relative to the control group and good potential as cell microcarriers after surface modification with polydopamine. The modified PCL porous microspheres implanted subcutaneously in rats underwent rapid in vivo degradation and tissue ingrowth. Overall, this study demonstrated an efficient strategy for the precise preparation of porous microspheres and investigated the potential of the as-prepared PCL porous microspheres as cell microcarriers and micro-scaffolds.