Structural Stabilities of Ordered Arrays of Nb-4 Clusters on NaCl(100) Surface

National Natural Science Foundation of China [10774124]Adsorption of ordered (2 x 2) arrays of Nb-4 clusters on the insulating surface of NaCl(100) is studied by the first-principles calculations within the density functional theory. The calculations on the relaxed geometries and cohesive energies show that both the tetrahedron and quadrangle-Nb-4 can be stably adsorbed on this substrate, which may have important applications. The adsorption of quadrangle-Nb-4 on the NaCl(100) surface is more stable than that of tetrahedron-Nb-4. Both the Nb-4 clusters studied and a single Nb atom prefer the top site of the Cl atom in the NaCl(100) surface. Electronic structure analysis suggests that the interactions between the Nb-4 clusters and the substrate are weak

Dynamics of multi-mode nonlinear internal waves in fluids of great depth

This paper is mainly concerned with the dynamics of strongly nonlinear internal waves in two-dimensional fluids of great depth. A fully nonlinear model for a three-layer fluid of great depth containing topography, a Miyata-Choi-Camassa (MCC)-type system, is developed based on the generalization of the Ablowitz-Fokas-Musslimani global-relation formulation for free-surface water waves. Mode-1 internal solitary waves are numerically found in the MCC-type equation using the Petviashvili iteration technique and in the full Euler equations based on the boundary integral equation method. The comparison between the results validates the broad applicability of the MCC-type system. Mode-2 internal solitary waves are found in the MCC-type equations and are shown to be a type of gap solitary wave. Using the multi-mode internal solitary-wave solutions in the MCC-type equations, we apply the conformal mapping technique to calculate streamlines and particle trajectories. For unsteady simulations, we propose a pseudo-spectral algorithm to handle the time-coupled equations and investigate the generation mechanism of multi-mode internal solitary waves due to the resonance effect of local protrusion on the rigid wall, as well as their collisions when the wall is flat. For flows past protrusion on the rigid wall, the flow speed can be divided into subcritical, transcritical, and supercritical. The shedding of multi-mode internal solitary waves can occur only in the transcritical region of flow speed. We implement the carving of bifurcation curves with inflection to achieve the regional delimitation and, based on this, the interpretation of the generation mechanism from a physical point of view

Conducting Psychological Studies via Open Data

在开放运动的潮流下,不同领域纷纷发布公众可以免费获取、自由使用的开放数据,其中不乏反映人类方方面面的大数据,为心理学研究提供崭新的资料。为了促进研究者对这些数据库的利用,本文对大量现有的具有心理学研究潜力的公开数据库进行了搜集和整理,介绍了通过数据搜索引擎、数据综合门户、专业领域数据集和已有的调查项目四种获取开放数据的途径,列举包括基因、神经、自然环境、社会环境等九大专业领域中利用开放数据展开心理学研究的范例。开放数据具有样本巨大多样,分析灵活,执行高效经济等优点,同时也面临数据重用的可靠性、心理、规范与技术方面的挑战。&nbsp;</p

Calculation and Analysis of Reliability of the Rotor System

【中文文摘】根据现场数据,着手计算和分析了某型号直升机旋翼系统的可靠性性能。在整理现场数据得到的随机截尾数据的基础上,采用极大似然估计法估计了该混合型数据的威布尔分布参数。运用故障树分析方法建立和分析了旋翼系统的故障树结构。最后,对旋翼系统的可靠性结果进行了分析

Effects of Sc addition on microstructure, phase evolution and mechanical properties of Al_0.2CoCrFeNi high-entropy alloys

l(0.2)CoCrFeNiSc(x) (x=0, 0.1, 0.2 and 0.3, molar fraction) alloys were prepared by arc melting. The effects of Sc addition on the microstructure, phase evolution and mechanical properties of Al0.2CoCrFeNiScx alloys were investigated. The results showed that Sc could refine grain size, change phase type and improve mechanical properties. The grain size of Al0.2CoCrFeNiSc0.3 alloy (8.5 mu m) was reduced by approximately 50.6% compared to that of Al0.2CoCrFeNiSc0.1 alloy (17.2 mu m). The crystal structure evolved from a single FCC phase to a mixed phase including two types of FCC phases and one type of BCC phase. The FCC phase mainly appeared in the regions of (Co, Cr, Fe)- rich dendrites and (Ni, Sc)-rich interdendrites; while the BCC phase was mainly located in the region of (Al, Ni)-rich interdendrites. The yield strength increased from 167 to 717 MPa as the x value in Al0.2CoCrFeNiScx alloy increased from 0 to 0.3, improved by 329.3%, which could be attributed to grain size strengthening, solid solution strengthening and phase evolution

表观弥散系数对磁共振引导聚焦超声术治疗子宫肌瘤效果的评估

目的探讨磁共振表观弥散系数（ADC）评估磁共振引导聚焦超声术（MRgFUS）治疗子宫肌瘤效果的价值。方法回顾性分析佛山市中医院2018年1月至2022年10月期间56例接受MRgFUS治疗子宫肌瘤患者治疗前、治疗3月后和6月后的MRI及临床资料，比较患者病灶ADC值与肌瘤的体积，症状严重评分（SSS）和子宫肌瘤症状-生活质量问卷（UFS-QOL）评分的相关性。使用方差分析比较治疗前后相关数据的差异，采用Pearson法进行数据的相关性分析。结果56例患者治疗前及治疗3个月后、6个月后病灶ADC值［（1.11±0.13）、（1.84±0.09）、（2.12±0.24），×10-3/（mm2/s）］、肌瘤体积（102±35.30、56.70±18.88、46.93±18.99，cm3），SSS（36.73±11.74、21.77±10.21、17.66±9.30）和UFS-QOL（59.05±17.48、76.54±16.50、82.46±12.37）评分差异有统计学意义（F值分别为557.837，73.589，53.976和37.606，P值均＜0.05）。ADC值与肌瘤体积、SSS呈负相关，与UFS-QOL评分呈正相关（相关系数分别为-0.586，-0.630和0.592，P值均＜0.05）。结论ADC值对评估MRgFUS治疗子宫肌瘤效果具有较好的临床应用价值

Jahn-Teller effect in the Nb planar atomic sheet

使用基于密度泛函理论的第一性原理平面波赝势法,研究了Nb二维单层原子薄片的结构稳定性和电子结构性质.对其所有的二维晶格结构的计算表明,由于Jahn-Teller效应,对称性较高的正方和六角晶格都是不稳定的二维结构.而稳定的二维结构是由对称性较高的六角晶格畸变后形成的对称性较差的斜方和中心长方结构.Nb单层原子薄片不能形成长方晶格结构.通过计算电子结构和Jahn-Teller效应,进一步讨论了这些结构的相对稳定性以及各二维晶格结构的电子能带和态密度等性质.The structural stability and electronic structures of Nb planar atomic sheets are studied by employing first-principles plane wave pseudopotential method based on the density functional theory. The calculations for all the 2-dimensional lattice structures show that, as a result of Jahn-Teller effect, the high-symmetry square and hexagonal two-dimensional structures are metastable. The most stable structures are the low-symmetry oblique and centered rectangular structures, which are the distorted structures of the hexagonal 2-D structure due to Jahn-Teller effect. The 2-D rectangular structure of Nb atomic sheet can not be formed. The relative structural stabilities, the electronic energy bands and the density of states are discussed based on the ab initio calculations and the Jahn-Teller effect.国家自然科学基金(批准号:10374076)资助的课题~

一种基于键合技术制作微波传输线的方法

本发明公开了一种基于键合技术制作微波传输线的方法，该方法包括：采用键合技术将外延片的外延材料层与键合基片键合在一起；去除外延片的衬底，露出外延片的外延材料层；对外延片的外延材料层进行刻蚀，制作外延器件，将微波传输线制作区域刻蚀至键合界面；在键合界面上制作作为电极传输线的微波传输线。利用本发明，在实现硅基器件集成的同时，可以更容易地制作高质量的微波传输线

钙钛矿/晶硅叠层太阳电池关键材料与技术研究进展

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