Facile synthesis of prickly platinum-palladium core-shell nanocrystals and their boosted electrocatalytic activity towards polyhydric alcohols oxidation and hydrogen evolution.

Herein, prickly platinum-palladium core-shell nanocrystals (Pt@Pd NCs) were prepared by a facile one-pot aqueous method, only taking sodium pyrrolidone carboxylate (PCA-Na) as the structure director and stabilizing agent. The products were mainly characterized by microscopic analysis, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), followed by discussing the formation mechanism in details. The electrochemical characterizations were examined by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA). The results revealed that the prepared architectures had the biggest current density (58.4 mA cm-2) for ethylene glycol oxidation, which is 3.5-fold, 1.2-fold, 2.3-fold and 2.4-flod enhancement relative to those of home-made single Pt nanoparticles (NPs) and Pd NPs, commercial Pt black and Pd black catalysts, respectively. Also, the obtained Pt@Pd NCs showed improved catalytic activity and stability towards glycerol oxidation and hydrogen evolution reactions compared to the references.

One-pot aqueous fabrication of reduced graphene oxide supported porous PtAg alloy nanoflowers to greatly boost catalytic performances for oxygen reduction and hydrogen evolution.

Herein, reduced graphene oxide supported porous PtAg alloy nanoflowers (PtAg NFs/rGO) were synthesized by a simple one-pot aqueous method using pyridinium-based dicationic ionic liquid (1,4-bis(pyridinium)butane dibromide, Bpb-2Br) as the new structure-director and stabilizing agent. The products were characterized by a series of techniques. The obtained nanocomposite had more positive onset potential (1.03 V) for oxygen reduction reaction (ORR) in alkaline electrolyte than those of commercial Pt/C (50 wt%, 0.96 V) and home-made Pt nanoparticles (NPs)/rGO (Pt NPs/rGO, 0.97 V), showing the enhanced catalytic performance for hydrogen evolution reaction (HER) with the positive onset potential (-26 mV) and a small Tafel slope (31 mV dec-1) relative to Pt/C (-18 mV, 31 mV dec-1) and Pt NPs/rGO (-42 mV, 36 mV dec-1) in 0.5 M H2SO4.

Melatonin modulates the functions of porcine granulosa cells via its membrane receptor MT2 in vitro.

Melatonin (N-acetyl-5-methoxytryptamine) is documented as a hormone involved in the circadian regulation of physiological and neuroendocrine function in mammals. Herein, the effects of melatonin on the functions of porcine granulosa cells in vitro were investigated. Porcine granulosa cells were cultivated with variable concentrations of melatonin (0, 0.001, 0.01, 0.1, 1.0, and 10ng/mL) for 48h. Melatonin receptor agonist (IIK7) and antagonist (Luzindole, 4P-PDOT) were used to further examine the action of melatonin. The results showed optimum cell viability and colony-forming efficiency of porcine granulosa cells at 0.01ng/mL melatonin for 48-h incubation period. The percentage of apoptotic granulosa cells was significantly reduced by 0.01 and 0.1ng/mL melatonin within the 48-h incubation period as compared with the rest of the treatments. Estradiol biosynthesis was significantly stimulated by melatonin supplementation and suppressed for the progesterone secretion; the minimum ratio of progesterone to estradiol was 1.82 in 0.01ng/mL melatonin treatment after 48h of cultivation. Moreover, the expression of BCL-2, CYP17A1, CYP19A1, SOD1, and GPX4 were up-regulated by 0.01ng/mL melatonin or combined with IIK7, but decreased for the mRNA levels of BAX, P53, and CASPASE-3, as compared with control or groups treated with Luzindole or 4P-PDOT in the presence of melatonin. In conclusion, the study demonstrated that melatonin mediated proliferation, apoptosis, and steroidogenesis in porcine granulosa cells predominantly through the activation of melatonin receptor MT2 in vitro, which provided evidence of the beneficial role of melatonin as well as its functional mechanism in porcine granulosa cells in vitro.

New formation of imines of C19-diterpenoid alkaloids by heating with DMSO.

Treatment of some C(19)-diterpenoid alkaloids (3, 6, 10 and 12) with anhydrous DMSO at 100-170 degrees C for 3-7 h led to the formation of the corresponding imines (4, 7/8, 11, 13/14) in 65-83% yield, respectively. This is a new simpler formation of the imines of the C(19)-diterpenoid alkaloids.