Regulating off-centering distortion maximizes photoluminescence in halide perovskites

Metal halide perovskites possess unique atomic and electronic configurations that endow them with high defect tolerance and enable high-performance photovoltaics and optoelectronics. Perovskite light-emitting diodes have achieved an external quantum efficiency of over 20%. Despite tremendous progress, fundamental questions remain, such as how structural distortion affects the optical properties. Addressing their relationships is considerably challenging due to the scarcity of effective diagnostic tools during structural and property tuning as well as the limited tunability achievable by conventional methods. Here, using pressure and chemical methods to regulate the metal off-centering distortion, we demonstrate the giant tunability of photoluminescence (PL) in both the intensity (>20 times) and wavelength (>180 nm/GPa) in the highly distorted halide perovskites [CH₃NH₃GeI₃, HC(NH₂)₂GeI₃, and CsGeI₃]. Using advanced in situ high-pressure probes and first-principles calculations, we quantitatively reveal a universal relationship whereby regulating the level of off-centering distortion towards 0.2 leads to the best PL performance in the halide perovskites. By applying this principle, intense PL can still be induced by substituting CH₃NH₃⁺ with Cs⁺ to control the distortion in (CH₃NH₃)_1-xCs_xGeI₃, where the chemical substitution plays a similar role as external pressure. The compression of a fully substituted sample of CsGeI₃ further tunes the distortion to the optimal value at 0.7 GPa, which maximizes the emission with a 10-fold enhancement. This work not only demonstrates a quantitative relationship between structural distortion and PL property of the halide perovskites but also illustrates the use of knowledge gained from high-pressure research to achieve the desired properties by ambient methods.     

区域创新要素配置的结构性特点分析——高技术产业的创新投入产出再分析

首先通过聚类的方法将行政区域按照它们在高技术产业技术能力的积累聚合划分为三类区域。由于三类地区的技术创新投入与产出结构之间存在相互的制约和影响,属于成分数据,本文运用偏最小二乘的方法,对这三类区域的创新人力投入结构以及资本投入结构和创新产出比例结构之间的关系进行实证研究。数据表明,不同类型的区域高技术产业的要素投入对创新产出的作用各不相同。本文的研究结果为政策制定以及高技术企业的发展提供实证依据。     

知识创新、动态能力与组织绩效的关系研究

 研究企业的知识创新、协调整合能力、重组转型能力和组织绩效之间相互影响的机制和路径。通过理论分析建立研究框架,并选取我国珠三角地区317家企业进行实证研究。结果表明,知识创新对组织绩效具有直接正向影响;知识创新对协调整合能力和重组转型能力均具有直接正向影响;协调整合能力对重组转型能力具有直接正向影响;协调整合能力和重组转型能力均可以直接提升绩效水平。本文的研究结果可为中国企业如何有效增强知识创新以提升动态能力和改善组织绩效提供有益的借鉴。     

稿件中学术不端行为检测结果的动态变化与成因分析

【目的】 探究编辑部对作者投稿进行第一次学术不端检测(以下简称“初检”)后,稿件中学术不端检测结果发生动态变化的成因,探索初检后学术不端的主动控制措施。【方法】 从笔者的经历以及相关学者的研究文献入手,分析造成稿件在初检后复制比发生动态变化的原因。【结果】 稿件在初检后学术不端检测结果发生动态变化的原因是稿件之间的抄袭,并且抄袭与被抄袭的论文都未进入数据库,其中一篇稿件刊发并且进入数据库后,其他稿件的学术不端即刻表现出来;分布的主要群体是师生、学术团队、同事和学术研究合作者;大多数学术不端内容在投稿前就已经存在,少数为作者投稿后修改期间植入;检测软件自身算法缺陷以及比对数据库更新周期滞后都是造成学术不端的检测结果动态变化的原因。【结论】 为了大幅度降低初检后学术不端的出现概率,编辑部应当实行优先发表、缩短稿件的出版周期、刊发前复检和采用两种主流学术不端检测软件交叉检测来稿等措施;数据库公司应当保证数据的正确性,缩短数据库的更新周期;软件开发公司应当优化软件算法,最大程度地健全、完备数据库。     

基于Py-GC-MS分析的桑枝热裂解有机结构变化研究

采用热裂解气质联用仪对桑枝进行了热解实验研究。原料的热解产物分布为:主要成分为含氧有机物,鉴定出12种物质。有二氧化碳、醛类化合物、酮类化合物、酸类化合物、酚类化合物,分别占桑枝杆总量的11.52%、17.97%、20.21%、13.57%、19.07%。根据桑枝红外光谱图分析,结合桑枝热解产物有机结构,进行了裂解过程物料结构变化分析。研究为生物质能源技术提供理论基础。     

合作关系中的组织间学习--一个动态的学习观

外部环境的恶化使组织间的合作日益增多，本文对合作关系的演变模式和常规演变模式下合作关系中的组织间学习进行了研究，提出了合作关系中学习的周期性，将学习分为四个阶段，并阐述了每个阶段的学习的特征。     

白春礼:从兵团战士到院士

<正>白春礼院士的经历很奇特,年少时他做文学梦,没想到却进入自然科学的前沿;他当过兵,开过大卡车,若干年后,这名热血澎湃的战士竟然成了世界闻名的科学家。 院士风采 盯了一天,记者才把白春礼院士从会场约出来,他出现在记者面前时,精神抖擞且不失儒雅,令人实在不能相信,这位浓眉大眼、和蔼可亲的英俊中年人竟然是一位51岁的院     

Collaborative working in a large pharmaceutical company: Developing better practices through a structurational schema

This paper presents the ongoing case study of a large pharmaceutical organisation currently undertaking a number of changes to their work practices. These collaborative changes are being facilitated by groupware systems. In many instances this has led to the rejection of or resistance to the more complex tools. The paper outlines research, based on a perspective informed by structuration theory, that provides the organisation with an approach to supporting staff in this new ‘collaborative environment’. An example, drawn from the case study, shows how such support might be developed and presents a set of recommendations for supporting a particular group, based on this research schema.     

中国创新地图——基于文献计量学的我国创新管理研究力量分布研究

 基于科学计量学方法,选择CNKI数据库,以国家自然科学基金委管理科学部遴选的20种管理学重要期刊为来源期刊,通过分析2000-2005年间发表在上述期刊上的创新管理研究文章,初步揭示了我国大陆地区创新管理研究现状。基本结论：《科学学研究》、《科研管理》、《研究与发展管理》是近年来创新管理学术研究的主要阵地;根据创新管理研究力量的强弱可以分为绝对优势地区、相对优势地区、潜力地区、相对劣势地区、绝对劣势地区五个层次;高校是我国创新管理研究的绝对主力军;浙江大学、西安交通大学、清华大学位列我国高水平创新管理研究的高产机构的前三位。     

Monitoring intellectual capital: a case study of a large company during the recent economic crisis

Nowadays, companies and organizations are facing a deep economic crisis as a follow-up of the financial crisis that started in 2007. This crisis has affected a great amount of markets and industries around the world. In this context, companies are challenging the way they allocate resources to investments, especially to intangibles. The present research considers this issue based on an empirical work carried out with a large company (called here Global A) and with reference to the cycle approach proposed by Åkerman. General conclusions are derived for how to approach intangibles (intellectual capital) in a downturn context.     

Employee relationship and knowledge sharing: a case study of a Taiwanese finance and securities firm

Knowledge Management Research & Practice - Knowledge is a very important resource for preserving valuable heritage, learning new things, solving problems, creating core competences, and...     

Innovation processes in large technical systems: Market liberalization as a driver for radical change?

Electricity supply is a large technical system, which exhibits strong path dependencies and high barriers for radical innovations. Recent market liberalization, however, has initiated a fundamental restructuring. The paper analyzes how liberalization has altered innovation processes in the field of electricity supply. We examine three radical innovations under monopoly conditions and contrast the findings with the results from a survey on the innovation behavior of electric utilities in liberalized markets. We argue that the selection environment for innovations has changed in various respects. In our sample, new options open to innovation activities have emerged at the level of the firm and utility strategies turn out to be more heterogeneous. This may be interpreted as an increase in the variety of search processes, which may lead to a mid-term decrease of path-dependencies.     

Managing the investment in information security technology by use of a quantitative modeling

This paper presents a mathematical model for an optimal security-technology investment evaluation and decision-making processes based on a quantitative analysis of the security risks and a digital-assets assessment in an organization. The model makes use of a quantitative analysis of different security measures that counteract individual risks by identifying the information-system processes in an enterprise and the potential threats. The model comprises the target security levels for all the identified core business processes and the probability of a security accident together with the possible loss the organization may suffer. The model allows in-depth analyses and computations providing quantitative assessments of different options for investments, which translate into recommendations that facilitate the selection of the best solution and the associated decision-making. The model was tested using empirical examples and mathematical simulations with data from a real business environment.     

基于连通性的引文网络结构分析新视角:主路径分析

引文网络主路径方法的提出对于解决特定学科(领域)的关键性文献识别和主流研究线索提取具有重要意义。本文从科学史研究与科学结构揭示的关键文献识别和主流研究提取的实践需求入手,深刻剖析引文网络主路径分析方法的产生背景、基本内涵与算法实现。从引文网络主路径分析的实践应用及与其它方法的整合两方面探讨该方法的演化发展状况,并总结主路径分析在理论及应用研究中存在的主要问题。     

The diffusion of ideas in the academy: A quantitative illustration from economics

It has long been recognised in policy discussion that the influence of new ideas depends not just on their generation but also on the way in which they diffuse through society. However, while the spread of new ideas in industry has been much studied, there are no similar quantitative studies on diffusion within the academy. This paper addresses that gap by providing quantitative evidence on the adoption of two techniques for empirically testing hypotheses in economics. On the basis of this evidence, and contrary to a common expectation, the spread of ideas seems neither straightforward nor especially rapid in the academy.