2D Metal Porphyrin-Based MOFs and ZIF-8 Composite-Derived Carbon Materials Containing M-Nx Active Sites as Bifunctional Electrocatalysts for Zinc-Air Batteries.

The main impediment to the development of zinc-air batteries is the sluggish kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Transition metal N-doped carbon catalysts offer a promising alternative to noble metal catalysts, with metal-organic framework (MOF)-derived carbon material catalysts being particularly noteworthy. Here, we synthesized MxP-Z-C carbon catalysts by combining two-dimensional (2D) metal porphyrin-based MOFs (MxPMFs, x = Fe, Co, Ni, Mn) and three-dimensional zeolitic imidazole framework-8 (ZIF-8) through electrostatic interaction, followed by carbonization. ZIF-8 was inserted between the layers of MxPMFs to prevent its Π-Π stacking, allowing the active sites to become fully exposed. MxP-Z-C demonstrated an impressive catalytic activity for both the ORR and the OER reactions. Among them, FeP-Z-C showed the best catalytic activity. The half-wave potential for ORR was 0.92 V (vs the reversible hydrogen electrode (RHE)), while the overpotential for the OER was 290 mV. In addition, the zinc-air battery assembled by FeP-Z-C exhibited high power density (133.14 mW cm-2) and significant specific capacity (816 mAh gZn-1), indicating considerable potential as a bifunctional catalyst for electronic devices.

Overview of the Shenzhen Emergency Medical Service Call Pattern / 世界急诊医学杂志（英文）

BACKGROUND: In Shenzhen, the Emergency Medical Service (EMS) system has been in service since 1997. This study aims to examine the operation of Shenzhen 120 EMS center and to identify the reasons of calling EMS. METHODS: In this retrospective quantitative descriptive study, the data from the Shenzhen 120 EMS registry in 2011 were analyzed. RESULTS: Shenzhen 120 EMS center is a communication command center. When the number of 120 are dialed, it is forwarded to the closest appropriate hospital for ambulance dispatch. In 2011, the Shenzhen 120 EMS center received 153160 ambulance calls, with an average of 420 calls per day. Calling emergency services was mainly due to traffic accidents. Trauma and other acute diseases constituted a majority of ambulance transports. The adult patients aged 15–60 years are the principal users of EMS. There are no recognized 'paramedic' doctors and nurses. The pre-hospital emergency service is under the operation of emergency departments of hospitals. Shenzhen at present does not have specialized pre-hospital training for doctors and nurses in post-trauma management. Moreover, specialized pre-hospital training, financial support, and public health education on proper use of EMS should be emphasized. CONCLUSION: The Shenzhen 120 EMS center has its own epidemiology characteristics. Traumatic injury and traffic accident are the main reasons for calling ambulance service. In-depth study emphasizing the distribution and characteristics of trauma patients is crucial to the future development of EMS.