A fast and versatile cross-linking strategy via o-phthalaldehyde condensation for mechanically strengthened and functional hydrogels

Fast and catalyst-free cross-linking strategy is of great significance for construction of covalently cross-linked hydrogels. Here, we report the condensation reaction between o-phthalaldehyde (OPA) and N-nucleophiles (primary amine, hydrazide and aminooxy) for hydrogel formation for the first time. When four-arm poly(ethylene glycol) (4aPEG) capped with OPA was mixed with various N-nucleophile-terminated 4aPEG as building blocks, hydrogels were formed with superfast gelation rate, higher mechanical strength and markedly lower critical gelation concentrations, compared to benzaldehyde-based counterparts. Small molecule model reactions indicate the key to these cross-links is the fast formation of heterocycle phthalimidine product or isoindole (bis)hemiaminal intermediates, depending on the N-nucleophiles. The second-order rate constant for the formation of phthalimidine linkage (4.3 M⁻¹ s⁻¹) is over 3000 times and 200 times higher than those for acylhydrazone and oxime formation from benzaldehyde, respectively, and comparable to many cycloaddition click reactions. Based on the versatile OPA chemistry, various hydrogels can be readily prepared from naturally derived polysaccharides, proteins or synthetic polymers without complicated chemical modification. Moreover, biofunctionality is facilely imparted to the hydrogels by introducing amine-bearing peptides via the reaction between OPA and amino group.     

基于知识外溢的合作研发知识产权风险及其影响因素分析

当前大部分关于合作研发中知识外溢的研究,都集中在从宏观层面讨论知识外溢对企业研发投资、合作收益性以及社会福利的影响,而很少从企业层面分析知识外溢给企业带来的风险。本文阐述了合作研发中企业知识外溢的机制及其引起的知识产权风险,并从知识特性、合作主体特性以及合作联盟的特性等几个方面分析了这种知识产权风险的影响因素。     

高校图书馆学科馆员与学科化知识服务

论文从分析高校图书馆开展知识服务的需求、学科馆员素质要求和知识服务模式入手,论述了新时期高校图书馆学科馆员的工作模式,指出为用户提供深层次、专业化、知识化、特色化的知识服务是提升高校图书馆知识服务能力的必由之路.图书馆学科化知识服务模式将成为高校图书馆未来最具潜力的一种服务模式.     

《中国中药杂志》量化考核机制的建立与实践

《中国中药杂志》根据现阶段期刊发展需求,探索出一套特色化、全方位的绩效考核管理机制。将编辑分为纸质版编辑、网络与信息编辑2种类型,并分设了不同的管理考核标准。对纸质版编辑的考核综合了选题组稿,文章的下载频次、被引频次、刊用周期,举办或参加会议与培训,参与基金项目,创收等多个方面;对网络与信息编辑的考核则侧重于激励研发与创新。对于编委会,也打破常规,采取量化考核与竞争机制。通过对编辑部和编委会实行特色化的量化考核、绩效管理制度,将编辑和专家的个人贡献与期刊整体发展紧密结合,充分发挥了其潜能和资源优势,使期刊综合实力得到迅速提升。     

Two decades of suspect evidence for adaptive molecular evolution—negative selection confounding positive-selection signals

There has been a large literature in the last two decades affirming adaptive DNA sequence evolution between species. The main lines of evidence are from (i) the McDonald-Kreitman (MK) test, which compares divergence and polymorphism data, and (ii) the phylogenetic analysis by maximum likelihood (PAML) test, which analyzes multispecies divergence data. Here, we apply these two tests concurrently to genomic data of Drosophila and Arabidopsis. To our surprise, the >100 genes identified by the two tests do not overlap beyond random expectation. Because the non-concordance could be due to low powers leading to high false negatives, we merge every 20–30 genes into a ‘supergene’. At the supergene level, the power of detection is large but the calls still do not overlap. We rule out methodological reasons for the non-concordance. In particular, extensive simulations fail to find scenarios whereby positive selection can only be detected by either MK or PAML, but not both. Since molecular evolution is governed by positive and negative selection concurrently, a fundamental assumption for estimating one of these (say, positive selection) is that the other is constant. However, in a broad survey of primates, birds, Drosophila and Arabidopsis, we found that negative selection rarely stays constant for long in evolution. As a consequence, the variation in negative selection is often misconstrued as a signal of positive selection. In conclusion, MK, PAML and any method that examines genomic sequence evolution has to explicitly address the variation in negative selection before estimating positive selection. In a companion study, we propose a possible path forward in two stages—first, by mapping out the changes in negative selection and then using this map to estimate positive selection. For now, the large literature on positive selection between species has to await reassessment.     

论数字参考咨询服务的知识管理

文章阐述了数字参考咨询服务的概念,分析了它与传统参考咨询服务的区别,总结了它的特征在于知识共享、服务共享和专家共享,并运用知识管理的有关理论对数字参考咨询如何加强知识管理提出了建议。     

网络环境下个性化信息服务的现状与前瞻

分析了个性化信息服务的内涵、现状及影响,并阐述了网络环境下个性化信息服务的发展趋势。     

任务驱动教学法下的能源与动力工程基础实验实训探索和改革

分析能源与动力工程基础实验实训现状和存在问题,将任务驱动教学法应用于基础实验实训,突出学生为主、融入新兴理念、培养创新意识、细化实训要求、完善考核机制和扎实能力培养.通过基础实验的自学和检测,锻炼学生操作实验、撰写报告和分析结果的能力.设计实验的任务驱动,给学生充分发展的平台,锻炼其自学、实践、表达和团队协作能力,培养...     

浅议数字图书馆的个性化信息需求服务

分析了数字图书馆开展个性化信息服务的必要性,着重探索数字图书馆个性化信息服务的构建,以满足用户的个性化需求。     

高校图书馆馆藏评价方针初探

论述了高校图书馆馆藏评价的方针和内容,指出了图书馆馆藏评价的意义。