be made into well-faceted morphologies of rhombic dodecahedrons or cubic hexahedrons. [13,14] A critical step for finally getting the hollow structures by using the template method is to remove the templates, which normally requires that the template materials have poorer thermal/chemical stability than the desired species attached on the templates. ZIF8 templates can be easily etched in a solution system, [13,[15][16][17] owing to their chemical instability. But some literatures also show that an annealing process can also remove ZIF8, [18][19][20] which especially in our detailed investigation, is not due to the poor thermal stability.In particular, when we coated a layer of polymerized dopamine (PDA) on rhombic dodecahedron nanoparticles of ZIF8, and annealed the ZIF8@PDA composites at a temperature of 900 °C, the obtained product is nitrogen doped carbon (NC) hollow structured materials, indicating that ZIF8, just like a hard template, can be removed at high-temperature for constructing the hollow interiors. While interestingly, when ZIF8 was solely calcined at 900 °C, it results in same shape, solid NC dodecahedron nanoparticles, indicating ZIF8 itself can well retain the original structures during heating treatment. This observation implies that the hollow structures obtained by annealing the composites are absolutely not derived from poor thermal stability of the ZIF8 cores and the existence of PDA layer may also contribute to the hollowing procedure.Considering the unusual observation, we then gave this hollowing process a detailed investigation and proposed a "stresses induced orientation contraction" mechanism to address it. Particularly, pure ZIF8 rhombic dodecahedrons would gradually decompose, shrink, and transfer into NC along temperature increase, in which the uniform shrinkage stresses applied on different directions could be well balanced, resulting in NC with well inherited shapes but smaller sizes. While for ZIF8@PDA composites, due to the intense PDA-ZIF8 interface interactions, the PDA layer strongly drags the ZIF8 outward to restrain their contraction, thus leading to accumulated stresses in the central part of ZIF8 dodecahedron nanoparticles and gradually damaged interior cores for creating the hollow structures. Besides, the achieved NC materials demonstrate a very high catalytic activity to ORR owing to the nice hollow structure and very high content of active pyridinic N. Indeed this work gives an absolutely novel Hollow structured materials are widely applicable in various fields. Although many routes have been explored for getting such materials, a strategy mainly based on physical effect is still deficient. Herein, a "stresses induced orientation contraction" mechanism for preparation of hollow structures is reported. The composites constructed by zeolite imidazolate framework-8 (ZIF8) cores and polymerized dopamine (PDA) shells, upon annealing, form intensive interfacial interactions, which drag the ZIF8 cores outward to restrain their shrinkage. The gradually accumulated stresses in...

the outbreak of the novel coronavirus SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) that originated in Wuhan, Hubei province has spread rapidly across China. Many hospitals in Wuhan are the epicenter of the outbreak. The first 14 staff members who were infected with SARS-Cov-2 were from our department. All of them recovered. In such an urgent and unexpected situation, our department began immediate and effective prevention and control strategies to stop the spread of the epidemic in the department. We believe that clinical departments, especially those related to noninfectious diseases in geographic areas of high risk for virus transmission, should take appropriate management and control measures to improve safety during this epidemic. For this purpose, we summarize and share our experiences which should help medical staff prepare in advance for a similar situation. These include the characteristics of SARS-Cov-2 infection, principles of prevention and control of infection, management of infected patients, and epidemic prevention in the outpatient department, ward, operating room, and medical staff.At the end of December 2019, several cases of pneumonia in Wuhan, China caused by an unknown virus were reported to the World Health Organization (WHO). The novel virus was initially identified as a coronavirus on January 7, 2020, and named "severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)" by WHO on February 11, 2020. The disease caused by SARS-CoV-2 is now known as coronavirus disease 2019 (COVID-19). According to the latest retrospective analysis, the median (range) incubation period of COVID-19 is 3 d, but incubation can be as long as 24 d. 1 The median age of patients is 47 yr, and adults are more susceptible than children and adolescents.There is no specific identifying symptom during the early stage of COVID-19 infection. Infected individuals may display weakness, cough, fever, or even no symptom, and yet they are already infectious. The accuracy of early diagnosis based on combined chest computed tomography and nucleic acid test can reach 97%. Expiratory dyspnea occurs in the late stages of infection, and respiratory distress syndrome, acute circulatory failure, or renal failure in severe cases. No specific effective therapeutic protocol in known. The current treatment methods are empiric based on symptoms, and consist of respiratory support (eg, oxygen, mechanical ventilation, or artificial lung technology), antibiotics, and antiviral drugs supplemented by immunoglobulin infusion. 1,2 The outbreak of COVID-19 in Wuhan occurred on the eve of the Chinese New Year (January 12, 2020). However, due to

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