Synergistic Pore Structure and Active Site Modulation in Co-N-C Catalysts Enabling Stable Zinc-Air Batteries.

Development of cheap, highly active, and durable nonprecious metal-based oxygen electrocatalysts is essential for metal-air battery technology, but achieving the balance of oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) bifunctional performance and long-term durability is still a great challenge. Using a typical Co-N-C catalyst as a model, herein, we introduced ammonium chloride into nitrogen-doped carbon materials containing metal elements during the pyrolysis process (Co-N-C/AC), which not only increases the active area but also realizes the accurate customization of the active site (pyridine nitrogen and cobalt oxide species) so as to achieve the balance of the OER/ORR bifunctional sites. The synthesized Co-N-C/AC bifunctional catalyst with a three-dimensional porous structure exhibits a smaller potential gap of 0.72 V. The peak power density of the aqueous cell at a current density of 308 mA cm-2 is 203 mW cm-2. The cycle life (≈3900 h) is longer than those of other recently reported aqueous Zn-air batteries (ZABs). The peak power density of the Co-N-C/AC-based quasi-solid-state ZAB reaches 550 mW cm-2 for ∼72 h. This work shows a feasible path for the practical application of ZABs by balancing the bifunctional electrocatalysts by tailoring the active site reasonably.

The Effect of Boredom on College Students' Meaning in Life: A Longitudinal Mediation Model.

Boredom is a common emotional experience in daily life adversely affecting individual physical health, mental health, and social functioning. Therefore, it is an important issue to improve the quality of life by ameliorating individuals' state of boredom. We used a longitudinal research approach. First, we tested 728 participants with the Multidimensional State Boredom Scale (MSBS). Then, after 3 months, the participants filled out the Cognitive Flexibility Inventory (CFI), Perceived Social Support Scale (PSSS), and Meaning of Life Questionnaire (MILQ); 715 valid questionnaires were obtained. Results showed that cognitive flexibility played a mediating role between boredom and the presence of meaning in life, but social support did not. The total effect of boredom on the presence of meaning in life was significant. Cognitive flexibility and social support played a mediating role between boredom and the search for meaning in life, respectively, but the overall effect of boredom on the search for meaning in life was not significant. This study found that boredom has different effects on the presence of meaning in life and the search for meaning in life. It can improve individuals' sense of meaning in life by reducing boredom and improving cognitive flexibility and social support.

Selective, Rapid, and Ratiometric Fluorescence Sensing of Homocysteine in Live Neurons via a Reaction-Kinetics/Sequence-Differentiation Strategy Based on a Small Molecular Probe.

Small molecular biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play essential roles in maintaining the redox homeostasis of biological systems, the disorders of which are closely associated with neuropathology. To date, many probes have been developed to identify Cys and GSH; however, due to the relatively low content and the high structural homology with Cys, there is still a lack of effective strategies to design probes enabling Hcy detection in physiological environments with high selectivity, high sensitivity, and rapid response. Herein, we developed a reaction-kinetics/sequence-differentiation strategy based on a dual-binding-site boron-dipyrrin (BODIPY) fluorophore, which was able to selectively distinguish Hcy from Cys and GSH within 50 s though a ratiometric fluorescence response mode. Benefiting from these features, the probe is capable of real-time imaging and quantitative analysis of intracellular Hcy in living neurons. Moreover, results of the disease-model experiments at the cellular level indicated a gradual increase of the Hcy level in neurons during the processes of aggregated amyloid-ß (Aß) peptide or ischemia treatment, which would further promote the neuron apoptosis. These findings provide the first direct experimental evidence for the impact of Alzheimer's disease and ischemic stroke on the Hcy metabolism of brain neurons and the associated neuron injury.

[Chemical constituents from herbs of Swertia mileensis].

OBJECTIVE: To study the chemical constituents of Swertia mileensis. METHOD: The air-dried whole plants of S. mileensis were extracted with 50% EtOH. The EtOH extract was suspended in H20 and extracted with petroleum ether, CHCl3 and n-BuOH successively. The compounds were isolated and purified by column chromatography from the CHCl3 fraction, and identified based on spectral analyses (MS, H-NMR, 13C-NMR). RESULT: Twelve compounds were isolated from S. mileensis, and were elucidated as 1,5, 8-trihydroxy-3-methoxyxanthone (1), 1-hydroxyl-2, 3, 5, 7-tetramethoxyxanthone (2), 1-hydroxyl-3, 5, 8-trimethoxyxanthone (3), 1-hydroxyl-2, 3, 4, 6-tetramethoxyxanthone (4), 1-hydroxyl-2, 3, 4, 7-tetramethoxyxanthone (5), 1,8-dihydroxy-3, 5-dimethoxyxanthone (6), 1, 7-dihydroxy-3, 8-dimethoxyxanthone (7), 1, 3, 5, 8-tetrahydroxyxanthone (8), balanophonin (9), oleanolic acid (10), maslinic acid (11), sumaresinolic acid (12). CONCLUSION: Compounds 1, 3, 7-9, 11 and 12 were obtained from S. mileensis for the first time.