Protected nodes and the collapse of Fermi arcs in high-T{c} cuprate superconductors

Angle resolved photoemission on underdoped Bi2Sr2CaCu2O8 reveals that the magnitude and d-wave anisotropy of the superconducting state energy gap are independent of temperature all the way up to T{c}. This lack of T variation of the entire k-dependent gap is in marked contrast to mean field theory. At T{c} the point nodes of the d-wave gap abruptly expand into finite length "Fermi arcs." This change occurs within the width of the resistive transition, and thus the Fermi arcs are not simply thermally broadened nodes but rather a unique signature of the pseudogap phase.     

Surface resonant-states-enhanced acoustic wave tunneling in two-dimensional phononic crystals

We show that by placing a metal plate next to a two-dimensional phononic crystal, acoustic waves can tunnel through the combined structure at a specific frequency that lies inside the band gap of the phononic crystal. The enhanced transmission is attributed to the coupling of the input waves with the acoustically resonant states created between the metal plate and the phononic crystal. Experiments are in excellent agreement with the theoretical predictions.     

Enhanced photovoltaic properties of polymer-fullerene bulk heterojunction solar cells by thermal annealing

The effect of a thermal annealing treatment on the performance of bulk heterojunction photovoltaic cells based on poly[2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene] (MEH-PPV) and fullerene (C₆₀) composites is investigated. Upon thermal annealing at 120 ^°C, short-circuit current and power conversion efficiency (η) are more than tripled, while a sharp rise by eight times in and η is found for the device annealed at 200 ^°C. It is concluded that the improved phase separation between MEH-PPV and C₆₀ leads to the enhancement of and η at 120 ^°C, while thermodynamic molecule arrangement at the higher temperature of ∼200 ^°C induces a significant increase in all photovoltaic parameters of composite devices except the open-circuit voltage .     

基于机械-化学的方法在硅表面制造功能化结构

"利用机械与化学结合的方法在芳烃重氮盐溶液中用金刚石刀具切削硅片,使得芳香烃分子和硅之间以共价键连接,实现了对硅片的"成形并功能化"的一步完成．研究了在大气环境如何利用金刚石刀具在硅表面加工出表面质量较好的微结构,为下一步在溶液中"成形并功能化"硅提供好的基底．在溶液中对硅表面进行可控自组装实验,初步研究了切削速度和组装时间对切削处生成自组装膜质量的影响,总结出较适合膜生长的参数．用X射线光电子能谱对自组装膜进行了检测,用扫描电子显微镜和原子力显微镜对自组装膜的表面形貌进行了表征,并用原子力显微镜对自     

Controlled synthesis of dendritic ruthenium nanostructures under microwave irradiation and their catalytic properties for p-chloronitrobenzene hydrogenation

Transition Metal Chemistry - In this study, the shape-controlled synthesis of ruthenium (Ru) nanostructures was examined using microwave irradiation. Dendritic Ru nanostructures, with an average...     

基于RST-QFD-Bayes的新型装甲装备通用质量特性评价指标体系构建研究

针对新型装甲装备通用质量特性评价指标体系难以确定的问题,在明确评价指标体系构建原则的基础上,结合新型装甲装备特点,确定了通用质量特性初始评价指标及指标筛选要求,运用QFD将新型装甲装备通用质量特性需求映射为评价指标筛选要求,采用粗糙集理论(Rough Set Theory,RST)确定了指标筛选重要度,考虑到关联度的不确定性及多个专家估计值的平均值和估计值的波动程度,将贝叶斯理论引入关系矩阵的确定中,用区间数确定了关联度,进行了评价指标筛选,构建了新型装甲装备通用质量特性评价指标体系,为新型装甲装备通用质量特性评价奠定了基础。     

定轴转动中打击中心位置分析

刚体定轴转动的打击中心是一个很重要的力学概念,但在很多《大学物理》教材中都没有介绍.本文以一根质量均匀分布的细杆绕端点作定轴转动为例,首先从动力学的角度,分析刚体的受力和力矩,根据动力学方程,分别计算出打击中心位置;然后从运动学角度出发,以转轴O点的切向速度和切向加速度等于零为条件,再分别寻找打击中心的位置.计算结果表明:上述4种方法得出的刚体打击中心位置是相同的.最后简介刚体打击中心在体育运动、日常生活中一些应用.