Investigation of block depth distribution in PS‐b‐PMMA block copolymer using ultra‐low‐energy cesium sputtering in ToF‐SIMS

Directed self‐assembly of block copolymers (BCPs) is a promising candidate for next generation nanolithography. In order to validate a given pattern, the lateral and in‐depth distributions of the blocks should be well characterized; for the latter, time‐of‐flight (ToF) SIMS is a particularly well‐adapted technique. Here, we use an ION‐TOF ToF‐SIMS V in negative mode to provide qualitative information on the in‐depth organization of polystyrene‐b‐polymethylmethacrylate (PS‐b‐PMMA) BCP thin films. Using low‐energy Cs⁺ sputtering and Bi₃⁺ as the analysis ions, PS and PMMA homopolymer films are first analyzed in order to identify the characteristic secondary ions for each block. PS‐b‐PMMA BCPs are then characterized showing that self‐assembled nanodomains are clearly observed after annealing. We also demonstrate that the ToF‐SIMS technique is able to distinguish between the different morphologies of BCP investigated in this work (lamellae, spheres or cylinders). ToF‐SIMS characterization on BCP is in good agreement with XPS analysis performed on the same samples. Copyright © 2013 John Wiley & Sons, Ltd.     

基于思维模型建构的高三化学复习教学*—— 以“平衡原理的应用”为例

以高三复习课“平衡原理的应用”为例,通过真实情境的剖析让学生感知模型,引导学生分析归纳提炼模型,并进行针对练习运用模型,变式训练体会模型,让学生在实践中以模型思维为突破,深入领悟建构模型的实质,有序解决复杂化学问题,提升科学思维能力,发展化学学科核心素养。     

Suppression of charge imbalance via Li+-Mn4+ co-incorporated Sr2YSbO6 red phosphors for warm w-LEDs

Mn⁴⁺-activated double perovskite phosphors with composition diversity have presented excellent luminescent performances. However, the charge imbalance between Mn⁴⁺ and matrix cations would increase non-radiative recombination and reduce the structural stability. Here, novel high-efficiency stable Li⁺/Mn⁴⁺ co-incorporated Sr₂YSbO₆ red phosphors are successfully synthesized via a solid-state reaction method for warm w-LEDs, where the Li⁺ ions have the effect of charge balance for Sr₂YSbO₆:Mn⁴⁺ and reduce the non-radiative energy transfer among Mn⁴⁺ ions. It is demonstrated that the substitution of Li⁺–Mn⁴⁺ pairs for Sb⁵⁺ can enhance the bonding with low-shifted diffraction peaks and high emission intensity, and prolong the decay lifetime, compared with those of Mn⁴⁺ single-doped ones. Impressively, the thermal stability is enhanced to 89.72% from 84.61% at the original value of 303 K. Finally, a w-LED device based on the optimal phosphor Sr₂YSbO₆:0.01Mn⁴⁺/0.01Li⁺ red component exhibits a correlated color temperature of 4487 K and color rendering index of 80.2. Therefore, the incorporated Li⁺ ions serve as both charge compensator and co-activator in Mn⁴⁺-activated double perovskite phosphors with the aim of high luminescent performance and thermal stability.     

高中化学必修课程“变化观念与平衡思想”学科核心素养的系统构成研究

“变化观念与平衡思想”学科核心素养的系统构成对开展“素养导向”的教学与评价具有重要意义。通过课标分析,基于学科能力模型明确了高中必修学段“变化观念与平衡思想”核心素养的核心知识与活动经验、认识方式、研究对象及问题情境、学科能力活动及其表现等4个维度的具体内涵,系统建构了高中化学必修课程“变化观念与平衡思想”学科核心素养模型。     

基于恒等变换的单摆振动解析逼近

应用修正的谐波平衡法构造了单摆大幅振动的解析逼近周期和周期解.通过引入三角变换或反三角变换将单摆振动方程恒等变形为关于新变量的Duffing方程或其他易于处理的非线性振动方程,利用牛顿谐波平衡法构造了单摆振动的解析逼近解.给出的解析逼近周期及周期解简单易用,几乎在振幅(初始摆角)的全部取值范围内,都有很高的逼近精度.     

Chemical depth profiling and 3D reconstruction of III–V heterostructures selectively grown on non‐planar Si substrates by MOCVD

The chemical characterization of novel 3D architectures with nanometre‐scale dimensions is extremely challenging. The chemical composition of InGaAs/AlAs quantum wells selectively grown in SiO₂ trenches, 100–300 nm wide, is studied. Combining high lateral resolution 3D ToF‐SIMS analysis and Auger measurements, the chemical composition of individual trenches was obtained confirming the uniformity of these III–V heterostructures. These results correlate well with an average approach using SIMS depth profiling. The effects of ion beam orientation on the surface topography of confined structures were highlighted. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

亮度优化立体视频视觉舒适度评价

结合立体视频帧左右视图的灰度图,采用鲁棒性算法与软剪刀算法相结合的"画笔"方案来提取立体视频帧的前景区域,合成视差图并提取水平视差,计算深度视差;根据主观评价结果建立视差深度-视觉舒适度模型,再结合亮度对视觉舒适度的评价模型进行优化,使模型的评分更接近人类视觉系统的评分;结合人类主观评价实验的结果,用逆向代入法求出模型的系数确定模型,最终实现基于人类视觉系统特性的对立体视频视觉舒适度的评价。实验结果表明:通过视觉舒适度模型计算得到的结果与人类主观评价结果之间的误差率不超过5%,其中大部分视频误差率不超过1%。说明评价模型更符合人类主观感知结果的立体视频视觉舒适度,模型评分更接近人类视觉系统特性的主观实验评分,这为立体视频舒适度的评价提供了参考。     

The electronic band structure analysis of OLED device by means of in situ LEIPS and UPS combined with GCIB

Low-energy inverse photoelectron spectroscopy (LEIPS) and ultraviolet photoelectron spectroscopy (UPS) incorporated into the multitechnique XPS system were used to probe the ionization potential and the electron affinity of organic materials, respectively. By utilizing gas cluster ion beam (GCIB), in situ analyses and depth profiling of LEIPS and UPS were also demonstrated. The band structures of the 10-nm-thick buckminsterfullerene (C₆₀) thin film on Au (100 nm)/indium tin oxide (100 nm)/glass substrate were successfully evaluated in depth direction.     

采用能量平衡黏附理论的灌水器泥沙-壁面黏附特性研究

为了从量化的角度评价灌水器的抗堵性能,从单个沙粒的角度,分析了其在滴灌灌水器迷宫流道内的行为,建立了基于能量平衡的颗粒黏附模型,并计算出黏附临界速度.通过粒子图像测速可视化试验与计算流体动力学数值模拟相结合的方法,对采用能量平衡的黏附理论模型进行了适用性验证.研究发现,当灌水器入口压力越大、颗粒粒径越大或者颗粒-壁面间...     

埋深比对地铁车站与临近多层建筑峰值加速度响应的影响

为了对城市密集建筑区的抗震设计提供理论依据和参考,以三层三跨岛式车站和多层框架建筑为研究对象,采用有限元软件Abaqus对层状场地中由地铁车站与两个框架结构所组成的左右对称模型进行数值模拟实验,分析了不同埋深比对结构-土-结构相互作用(structure-soil-structure interaction, SSSI)效应的影响规律。结果表明,在地震作用下,当地铁车站埋深比小于等于1.5时,地铁车站与临近多层框架建筑间的SSSI效应对车站下半部分和上方框架结构所产生的不利影响值得重视;在埋深比增大过程中,临近建筑对车站上半区域的有利影响以及对车站整体的其他影响逐渐减弱,而车站对临近建筑的影响会整体趋向有利;地震动的频谱特性是地铁车站与临近多层建筑间地震反应的主要影响因素之一。