Stacking sequence determines Raman intensities of observed interlayer shear modes in 2D layered materials - A general bond polarizability model

2D layered materials have recently attracted tremendous interest due to their fascinating properties and potential applications. The interlayer interactions are much weaker than the intralayer bonds, allowing the as-synthesized materials to exhibit different stacking sequences (e.g. ABAB, ABCABC), leading to different physical properties. Here, we show that regardless of the space group of the 2D material, the Raman frequencies of the interlayer shear modes observed under the typical configuration blue shift for AB stacked materials, and red shift for ABC stacked materials, as the number of layers increases. Our predictions are made using an intuitive bond polarizability model which shows that stacking sequence plays a key role in determining which interlayer shear modes lead to the largest change in polarizability (Raman intensity); the modes with the largest Raman intensity determining the frequency trends. We present direct evidence for these conclusions by studying the Raman modes in few layer graphene, MoS2, MoSe2, WSe2 and Bi2Se3, using both first principles calculations and Raman spectroscopy. This study sheds light on the influence of stacking sequence on the Raman intensities of intrinsic interlayer modes in 2D layered materials in general, and leads to a practical way of identifying the stacking sequence in these materials.Comment: 30 pages, 8 figure

手术分级管理与ICD-9-CM-3手术编码的探索*

Surgery grading management is one of the key aspects of medical technology access and medical quality management. Surgical classification is graded by risk level, the degree of difficulty of the process and the technology; however, surgery coding is mainly classified by the surgical site. Therefore, the grading of the ICD coding surgical name encounters some difficulties. Our hospital uses the “Jiangsu Province set of medical information classification and coding standards” and “Jiangsu Province surgery hierarchical directory”, which is issued by Jiangsu Provincial Commission of Health and Family Planning, as the basis. We are practicing and exploring about the correspondence between the surgery which has graded and ICD-9-CM-3 encoding, including six categories problems, such as different types of the same operation, different surgeries of the same parts. We carry out the surgical grading and coding intelligent management into hospital management, which will regulate the management of hospital surgery more effectively, ensure the safety of medical quality, and reduce the incidence of adverse events in health care.手术分级管理是医疗技术准入、医疗质量管理等的关键环节之一。手术分级是按风险高低、过程难易、技术难易程度进行分级的，而手术编码是按手术部位进行分类的，因此对ICD编码的手术名称逐一进行分级存在一定困难。本院以江苏省卫生计生委下发的“江苏省医疗信息分类编码标准集”及“江苏省手术分级目录”为依据，对已分级的手术与ICD-9-CM-3手术编码之间的对应关系进行了实践与探索，包括6类问题，如同一手术不同类型、同一部位不同手术等。将手术分级与手术编码智能化管理落实到医院诊疗实践中，会更有效的规范医院手术、保障医疗安全、减少医疗不良事件的发生