Exploration of a MgO cathode for improving the intensity of pulsed discharge plasma at atmosphere

With regard to the lower density and energy of electrons in pulsed discharge plasma （PDP） at atmosphere, leading to the lower energy utilization of plasma, we propose a MgO cathode to enhance the plasma intensity according to field emission principle. The MgO cathode is prepared by an electro-depositing MgO film on a stainless steel plate. This way, the positive charges come to the cathode and accumulate on the surface of the MgO film, leading to the enhancement of the electric field intensity between the cathode and MgO film, and result in the strong emission of secondary electrons from the MgO cathode. As a result, the intensity of plasma can be enhanced. Herein, the effect of the MgO cathode on the intensity of PDP is investigated. It was shown that the discharge peak current was improved by 20% compared with that of without the MgO cathode. With increasing the MgO film thickness, discharge intensity, including the peak current, transforming charge and spectrum intensity first increased and then decreased. Higher enhancement of peak current, transforming charge and spectrum intensity were acquired with a higher peak voltage. Compared to a cathode without MgO film, the ozone production is higher with MgO cathode employed. The research proposes a novel approach for improving the intensity of discharge plasma, and also provides a reference for further application of PDP.

新型冠状病毒(2019-nCoV)感染的肺炎诊疗快速建议指南(完整版)

2019新型冠状病毒(2019 novel coronavirus,2019-nCoV)感染的肺炎,因2019年12月发生在武汉的不明原因病毒性肺炎病例而被发现,并于2020年1月12日被世界卫生组织(World Health Organization,WHO)命名。在之后的一个月时间内,2019-nCoV在湖北省内外甚至其他国家传播造成了数以千计的病例出现,同时也引起了民众一定程度的恐慌。本指南的制订希望能够从疾病流行病学、病因学、诊断、治疗、护理、医院感染控制等方面给临床医生、社区居民等提供医疗护理及居家照护相关指导。

Au-catalysed free-standing wurtzite structured InAs nanosheets grown by molecular beam epitaxy

In this study,we report the growth of free-standing InAs nanosheets using Au catalysts in molecular beam epitaxy.Detailed structural characterizations suggest that wurtzite structured InAs nanosheets,with features of extensive{1120}surfaces,grown along the<1102>direction and adopted{0001}nanosheet/catalyst interfaces,are initiated from wurtzite structured[0001]nanowires as the inclined epitaxial growth due to relatively higher In concentrations in Au catalysts,and grown from these inclined nanostructures through catalyst-induced axial growth and their enhanced lateral growth under the high growth temperature.Based on the facts that the nanosheets contain large low energy{1120}surfaces and{0001}nanosheet/catalyst interfaces,the growth of our nanosheets is a thermodynamically driven process.This study provides new insights into fabricating free-standing Ⅲ-Ⅴ nanosheets for their applications in future nanoscale devices.

Transition pathways in Cylinder-Gyroid interface

When two distinct ordered phases contact,the interface may exhibit rich and fascinating structures.Focusing on the Cylinder-Gyroid interface system,transition pathways connecting various interface morphologies are studied armed with the Landau–Brazovskii model.Specifically,minimum energy paths are obtained by computing transition states with the saddle dynamics.We present four primary transition pathways connecting different local minima,representing four different mechanisms of the formation of the Cylinder-Gyroid interface.The connection of Cylinder and Gyroid can be either direct or indirect via Fddd with three different orientations.Under different displacements,each of the four pathways may have the lowest energy.

Some thoughts on conducting and implementing clinical practice guidelines in a pandemic

A pandemic is a disease that spreads worldwide.When disease is new such as coronavirus disease 2019(COVID-19),evidentiary basis,by definition,to prevent,diagnose,and treat the disease is limited.Nevertheless,clinical practice guidelines are urgently required to assist policy and healthcare workers to make informed decisions.But,acting in the high-quality evidentiary vacuum,that is,basing guidelines on poor-quality research can be counterproductive and potentially harmful.[1,2] Thus,guideline developers face a number of challenges during a pandemic like COVID-19 that we wish to address in this paper.