PtNi alloy nanoparticles grown in situ on nitrogen doped carbon for the efficient oxygen reduction reaction.

Currently, Pt based materials are still the most efficient oxygen reduction reaction (ORR) catalysts. However, their poor stability obstructs the commercial viability of fuel cells. To lower the reaction potential barrier and enhance the stability, we constructed alloy PtNi nanoparticles (NPs) with a Pt-rich surface supported on nitrogen-doped carbon (NC) via a simple one-step solvothermal method using easily accessible reagents. The synthesized PtNi/NC exhibits enhanced mass activity (MA), specific activity (SA), and positive onset potential compared with commercial Pt/C catalysts. Meanwhile, the half-wave potential shifted negatively to only 18 mV after 5000 cycles for PtNi/NC, indicating excellent stability. The enhanced ORR performance can be ascribed to the introduction of Ni into Pt optimizing the adsorption energy of Pt towards oxygen by adjusting the d band center of the Pt atom and stronger interaction between the metal NPs and support. Our work provides a potential synthesis strategy for developing a Pt-based catalyst with a low Pt loading and high ORR performance.

Optimizing elicitation strategy of salicylic acid for flavonoid and phenolic production of fed-batch cultured Oplopanax elatus adventitious roots.

Oplopanax elatus is a valuable medicinal plant, but its plant resource is lacking. Adventitious root (AR) culture of O. elatus is an effective way for the production of plant materials. Salicylic acid (SA) exerts enhancement effect on metabolite synthesis in some plant cell/organ culture systems. To clarify the elicitation effect of SA on fed-batch cultured O. elatus ARs, this study investigated the effects of SA concentration, and elicitation time and duration. Results showed that flavonoid and phenolic contents, and antioxidant enzyme activity obviously increased when the fed-batch cultured ARs were treated with 100 µM SA for 4 days starting on day 35. Under this elicitation condition, total flavonoid and phenolic contents reached 387 rutin mg/g DW and 128 gallic acid mg/g DW, respectively, which were significantly (p < 0.05) higher than those in the SA-untreated control. In addition, DPPH scavenging and ABTS+ scavenging rates, and Fe2+ chelating rate also greatly increased after SA treatment, and their EC50 values were 0.0117, 0.61, and 3.34 mg/L, respectively, indicating the high antioxidant activity. The findings of the present study revealed that SA could be used as an elicitor to improve the flavonoid and phenolic production in fed-batch O. elatus AR culture.

Selection of initial culture medium in fed-batch bioreactor culture of Rhodiola sachalinensis cells.

In fed-batch culture, numerous factors, such as initial culture conditions and feeding strategies, affect the culture efficiency. Among the factors, the effect of initial culture medium is rarely investigated. In this work, Rhodiola sachalinensis cells were cultured in the fed-batch bioreactor system and the effects of volume, medium strength, and sucrose concentration of initial culture medium on biomass and accumulation of salidroside, polysaccharides, flavonoids, and phenolics were investigated. The results showed that an initial medium volume of 3 L significantly (p < 0.05) increased biomass and the four bioactive compound contents. The maximum biomass and the highest contents of different bioactive compounds were determined at various MS medium strengths. Therefore, analytic hierarchy process (AHP) - technique for order preference by similarity to ideal solution (TOPSIS) was implemented and half-strength MS medium was selected. Furthermore, the effect of sucrose concentration was examined and 30 g/L sucrose in the initial medium was optimal, at which concentration, 39.45 mg/g DW of salidroside, 531.25 mg/g DW of total polysaccharides, 3.89 mg/g DW of total flavonoids, and 10.84 mg/g DW of total phenolics were produced. The findings of the present study provided a reference for further establishing the fed-batch culture system of R. sachalinensis cells.

Therapeutic Role of miR-30a in Lipoteichoic Acid-Induced Endometritis via Targeting the MyD88/Nox2/ROS Signaling.

Staphylococcus aureus (S. aureus), a notorious pathogenic bacterium prevalent in the environment, causes a wide range of inflammatory diseases such as endometritis. Endometritis is an inflammatory disease in humans and mammals, which prolongs uterine involution and causes great economic losses. MiR-30a plays an importan trole in the process of inflammation; however, the regulatory role of miR-30a in endometritis is still unknown. Here, we first noticed that there was an increased level of miR-30a in uterine samples of cows with endometritis. And then, bovine endometrial epithelial (BEND) cells stimulated with the virulence factor lipoteichoic acid (LTA) from S. aureus were used as an in vitro endometritis model to explore the potential role of miR-30a in the pathogenesis of endometritis. Our data showed that the induction of the miR-30a expression is dependent on NF-κB activation, and its overexpression significantly decreased the levels of IL-1ß and IL-6. Furthermore, we observed that the overexpression of miR-30a inhibited its translation by binding to 3'-UTR of MyD88 mRNA, thus preventing the activation of Nox2 and NF-κB and ROS accumulation. Meanwhile, in vivo studies further revealed that upregulation of miR-30a using chemically synthesized agomirs alleviates the inflammatory conditions in an experimental mouse model of endometritis, as indicated by inhibition of ROS and NF-κB. Taken together, these findings highlight that miR-30a can attenuate LTA-elicited oxidative stress and inflammatory responses through the MyD88/Nox2/ROS/NF-κB pathway and may aid the future development of novel therapies for inflammatory diseases caused by S. aureus, including endometritis.