Magnetically encoded 3D mesostructure with high-order shape morphing and high-frequency actuation

Inspired by origami/kirigami, three-dimensional (3D) mesostructures assembled via a mechanics-guided approach, with reversible and maneuverable shape-morphing capabilities, have attracted great interest with regard to a broad range of applications. Despite intensive studies, the development of morphable 3D mesostructures with high-order (multi-degree-of-freedom) deformation and untethered high-frequency actuation remains challenging. This work introduces a scheme for a magnetically encoded transferable 3D mesostructure, with polyethylene terephthalate (PET) film as the skeleton and discrete magnetic domains as actuation units, to address this challenge. The high-order deformation, including hierarchical, multidirectional and blending shape morphing, is realized by encoding 3D discrete magnetization profiles on the architecture through ultraviolet curing. Reconfigurable 3D mesostructures with a modest structural modulus (∼3 GPa) enable both high-frequency (∼55 Hz) and large-deformation (∼66.8%) actuation under an alternating magnetic field. Additionally, combined with the shape-retention and adhesion property of PET, these 3D mesostructures can be readily transferred and attached to many solid substrates. On this basis, diverse functional devices, including a switchable colour letter display, liquid mixer, sequential flashlight and biomimetic sliding robot, are demonstrated to offer new perspectives for robotics and microelectronics.     

技术创业企业商业模式创新前因的组态效应

为剖析技术创业企业商业模式创新多重前因的联动效应,基于商业模式冰山理论构建了商业模式创新的前因要素模型,以31家技术创业企业为样本,采用模糊集定性比较分析方法,分析了技术创业企业商业模式创新多重前因的联动效应。研究结果表明:(1)技术创业企业商业模式创新具有"多重并发"和"殊途同归"的特点,单一要素难以构成商业模式创新的必要条件;(2)网络嵌入与资源整合能力的协同作用对技术创业企业商业模式创新至关重要;(3)在高度的环境不确定情况下,资源整合能力和机会识别能力的协同作用,以及网络嵌入和战略柔性的协同作用是技术创业企业商业模式创新的重要途径。本研究进一步发展了商业模式冰山理论,丰富了商业模式创新前因的研究成果,为解释既有研究的分歧提供了新视角,也为技术创业企业根植自身情境实现商业模式创新提供了理论指导。     

论我国人大特定问题调查中的强制性权力

我国县级以上各级人大及其常委会有权组织特定问题调查委员会,但宪法和法律没有赋予人大及其常委会在特定问题调查中的强制性权力.在现行法律下,人大也不宜直接利用行政、司法机关的强制权,命令它们采取强制性调查措施.为了保障特定问题调查的顺利进行,法律有必要授予人大及其常委会特定问题调查中必要的强制性权力,并要求由行政、司法机关予以执行.     

按收入比例偿还国家助学贷款的SWOT分析

澳大利亚高等教育贡献方案中确立的按收入比例还款计划由于保障了低收入者的利益、回收率高等特点而成为各国竞相效仿的对象。目前我国的国家助学贷款仍然主要采取定期定额还款的方式,按收入比例还款未被纳入正轨的贷款回收系统之中,使得按收入比例这种还款方式难以发挥自身的优势。     

图书馆网站开展继续教育生就业信息专题服务现状分析及思考

提出高等院校图书馆网站也要重视和开展继续教育学生就业信息特色专题服务,分析和探索了图书馆网站在从事这项专题服务的现状、存在的问题及相应的发展思路。     

A proof of concept for neutralizing antibody-guided vaccine design against SARS-CoV-2

Mutations and transient conformational movements of the receptor binding domain (RBD) that make neutralizing epitopes momentarily unavailable present immune escape routes for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To mitigate viral escape, we developed a cocktail of neutralizing antibodies (NAbs) targeting epitopes located on different domains of spike (S) protein. Screening of a library of monoclonal antibodies generated from peripheral blood mononuclear cells of COVID-19 convalescent patients yielded potent NAbs, targeting the N-terminal domain (NTD) and RBD domain of S, effective at nM concentrations. Remarkably, a combination of RBD-targeting NAbs and NTD-binding NAbs, FC05, enhanced the neutralization potency in cell-based assays and an animal model. Results of competitive surface plasmon resonance assays and cryo-electron microscopy (cryo-EM) structures of antigen-binding fragments bound to S unveil determinants of immunogenicity. Combinations of immunogens, identified in the NTD and RBD of S, when immunized in rabbits and macaques, elicited potent protective immune responses against SARS-CoV-2. More importantly, two immunizations of this combination of NTD and RBD immunogens provided complete protection in macaques against a SARS-CoV-2 challenge, without observable antibody-dependent enhancement of infection. These results provide a proof of concept for neutralization-based immunogen design targeting SARS-CoV-2 NTD and RBD.     

《中书备对》户口资料解析

《中书备对》是现存唯一保存有宋代全国户数、口数和丁数等人口资料的重要文献,但在关于宋代人口问题的讨论中,对这一文献的研究和利用很不充分,有些讨论者甚至忽视它的存在。本文通过考证,确认《中书备对》之户口资料的纪年为元丰二年;所收录的户数为负担赋役的主客户,口数为负担赋役的主客户之著籍男子数,丁数为担负赋役的男子数。     

小学数学作业批改现状的调查分析

一、问题的提出教学过程是教师和学生的一种双边活动,备课、上课、课外辅导和作业批改都是教学过程不可缺少的重要环节。作业批改能反映教学面临的症结,是对学生作业状况的审查和评价。教师通过作业批改获得反馈信息,诊断课堂教学效果,适时地调控对作业布置中的“量”和“度”方面的问题,随时解决学生存在的问题,为后续的教学工作打好基础。因此作业批改的研究是非常必要的。作业批改包括三个方面：一是指出或改正错误即“改”,二是对作业状况写出批语,即“批”,三是评分。本次作业批改研究主要指小学四、五年级数学书面作业的批改情况。     

高校的学术研究与育人使命

全面贯彻中共中央《关于进一步繁荣发展哲学社会科学的意见》,应努力改变高校哲学社会科学学术研究"育人"功能薄弱的现状,在学术研究取向上和大学生文化品格发育事实相沟通;摈弃庸俗,规范学术行为,以崇高的学术精神赢得学生的尊重和向往;拓展学术研究视野,克服网络技术障碍,提高学术对话水平,在当代大学生的文化品格养成上有所作为。