研究型大学本科教育改革方向是近20年高等教育领域改革探索的难题之一。清华大学钱学森力学班（“钱班”）是我国“珠峰计划”的基础学科拔尖计划改革试点样本之一。论文基于“钱班”试点以来大量的官方文件、会议记录等静态数据，以及两年多的参与式观察、深度访谈等动态数据，综合运用档案研究、案例研究等质性研究方法进行了多重分析。研究发现：相比于传统本科教育组织方式，“钱班”历时10余年的试点实践，探索了“课程精深学习+进阶性科研训练”双轴驱动培养模式，并从“知识和经验的整合、时间与空间的拓展、师生互动方式和学生自我建构”四个维度比较系统地对理工类本科拔尖人才培养的核心要素和运行机理作了重新界说。“钱班”模式为推动新时期高质量、内涵式本科教育发展与改革工作提供了不同视角的参照框架。

行健书院是清华大学于2020年为落实国家强基计划、进一步推进学校本科人才培养改革而建立的五个书院之一.行健书院以培养具有深厚的数学和力学基础、面向若干关键领域的未来创新人才为目标.两年来,书院创建深厚的共同核心基础、多类路径多层出口的培养体系,设置挑战性问题牵引、进阶式科研训练,通过全覆盖导师制倡导从游文化、鼓励学生多样发展,积极探索更加全面地评价学生成长,开展全方位的人才培养改革.行健书院一系列改革举措取得了初步的成效,也将在中国特色、清华风格的书院制建设中不断探索.

Micro-funnels have been widely applied to produce extensionally dominant flows for DNA manipulation, such as DNA extension for DNA mapping and DNA fragmentation for gene sequencing. However, it still lacks a systematic understanding of DNA fragmentation behaviors in complicated flow fields regulated by different funnel shapes with high flow rates. This limits the rational design and application scope of related microfluidic devices. In this study, fragmentation experiments of λ DNA were carried out in microfluidic chips with four different micro-funnel shapes, namely a sudden finish, a linear contraction, a constant acceleration, and an increasing extension rate funnel. The experimental results demonstrated a significant effect of the micro-funnel shape on the produced DNA fragment size. Then, the dynamical behaviors of DNA molecules in flow fields created by different micro-funnels were simulated using a numerical method of Brownian dynamics-computational fluid dynamics. The numerical simulation revealed that both the magnitude and distribution of the extension rate of flow fields were drastically altered by the funnel shape, and the extension rate at the micro-scale was the dominant factor of DNA fragmentation. The different DNA fragmentation behaviors in four micro-funnels were investigated from the perspectives including the fragment size distribution, fragmentation location, percentage of broken molecules, conformational type and stretched length of DNA before fragmentation. The results elucidated the significant impact of funnel shape on the dynamical behaviors of DNA fragmentation. This study offers insights into the rational design of microfluidic chips for DNA manipulation.

面向第四次产业革命,培养能够实现"从0到1"范式突破的创新人才,并建立高质量创新人才培养的长效机制,不仅是关系到"两个大局"如何破局的关键问题,更是关系到中华民族百年大计甚至千年大计的重大命题.清华大学钱学森力学班(以下简称"清华钱班")经过10年的探索,初步实现了对上述命题的"点"突破.在此基础之上,清华钱班与深圳有关部门经过近1年的共同探索,共同构建了体现我国制度和文化优势的创新人才培养机制——"零一学院".相信沿着这个方向坚持10年,一定可以初步建立一个以深圳为起点,辐射全国的创新人才培养体系,为高等教育提供一个拔尖创新人才培养的新范式.

Bacterial cells have characteristic spatial and temporal scales. For instance, Escherichia coli, the typical rod-shaped bacteria, always maintains a relatively constant cell width and cell division time. However, whether the external physical perturbation of cell width has an impact on cell division time remains largely unexplored. In this work, we developed two microchannel chips, namely straight channels and ‘necked’ channels, to precisely regulate the width of E. coli cells and to investigate the correlation between cell width and division time of the cells. Our results show that, in the straight channels, the wide cells divide much slower than narrow cells. In the ‘necked’ channels, the cell division is remarkably promoted compared to that in straight channels with the same width. Besides, fluorescence time-lapse microscopy imaging of FtsZ dynamics shows that the cell pre-constriction time is more sensitive to cell width perturbation than cell constriction time. Finally, we revealed a significant anticorrelation between the death rate and the division rate of cell populations with different widths. Our work provides new insights into the correlation between the geometrical property and division time of E. coli cells and sheds new light on the future study of spatial–temporal correlation in cell physiology.

当前,技术支持的学习主要以教授既有知识的“慕课”模式为主.随着智能信息技术的迅速发展,技术支持的学习模式应重视探索创新驱动学习(innovative-oriented learning).塔迪教授指出,面向未来的学习和人才培养需致力于培育青少年的创新能力,解决未知难题.因此,构建学习与创新的“第三空间”,为创造性人才的培育给予系统性支持尤为必要.展望未来,转变学习范式、升级智能技术及制定教育政策将对持续推进技术支持的创新驱动学习有所助益.

Automated cell classification is an important yet a challenging computer vision task with significant benefits to biomedicine. In recent years, there have been several studies attempted to build an artificial intelligence-based cell classifier using label-free cellular images obtained from an optical microscope. Although these studies showed promising results, such classifiers were not able to reflect the biological diversity of different types of cell. While in terms of malignant cell, it is well-known that intracellular actin filaments are altered substantially. This is thought to be closely related to the abnormal growth features of tumor cells, their ability to invade surrounding tissues and also to metastasize. Therefore, being able to classify different types of cell based on their biological behaviors using automated technique is more advantageous. This article reveals the difference in the actin cytoskeleton structures between breast normal and cancer cells, which may provide new information regarding malignant changes and be used as additional diagnostic marker. Since the features cannot be well detected by human eyes, we proposed the application of convolutional neural network (CNN) in cell classification based on actin-labeled fluorescence microscopy images. The CNN was evaluated on a large number of actin-labeled fluorescence microscopy images of one human normal breast epithelial cell line and two types of human breast cancer cell line with different levels of aggressiveness. The study revealed that the CNN performed better in the cell classification task compared to a human expert.

DNA combing is a widely used method for stretching and immobilising DNA molecules on a surface. Fluorescent labelling of genomic information enables high-resolution optical analysis of DNA at the single-molecule level. Despite its simplicity, the application of DNA combing in diagnostic workflows is still limited, mainly due to difficulties in analysing multiple small-volume DNA samples in parallel. Here, we report a simple and versatile microfluidic DNA combing technology (μDC), which allows manipulating, stretching and imaging of multiple, microliter scale DNA samples by employing a manifold of parallel microfluidic channels. Using DNA molecules with repetitive units as molecular rulers, we demonstrate that the μDC technology allows uniform stretching of DNA molecules. The stretching ratio remains consistent along individual molecules as well as between different molecules in the various channels, allowing simultaneous quantitative analysis of different samples loaded into parallel channels. Furthermore, we demonstrate the application of μDC to characterise UVB-induced DNA damage levels in human embryonic kidney cells and the spatial correlation between DNA damage sites. Our results point out the potential application of μDC for quantitative and comparative single-molecule studies of genomic features. The extremely simple design of μDC makes it suitable for integration into other microfluidic platforms to facilitate high-throughput DNA analysis in biological research and medical point-of-care applications.

Natural selection is thought to shape the evolution of aging patterns, although how life-history trajectories orchestrate the inherently stochastic processes associated with aging is unclear. Tracking clonal growth-arrested Escherichia coli cohorts in an homogeneous environment at single-cell resolution, we demonstrate that the Gompertz law of exponential mortality characterizes bacterial lifespan distributions. By disentangling the rate of aging from age-independent components of longevity, we find that increasing cellular maintenance through the general stress pathway reduces the aging rate and rescales the lifespan distribution at the expense of growth. This trade-off between aging and growth underpins the evolutionary tuning of the general stress response pathway in adaptation to the organism's feast-or-famine lifestyle. It is thus necessary to involve both natural selection and stochastic physiology to explain aging patterns.

Mechanical factors play critical roles in mammalian development. Here, we report that colony-growing mouse embryonic stem cells (mESCs) generate significant tension on the colony surface through the contraction of a three-dimensional supracellular actomyosin cortex (3D-SAC). Disruption of the 3D-SAC, whose organization is dependent on the Rho/Rho-associated kinase (ROCK) signals and E-cadherin, results in mESC colony destruction. Reciprocally, compression force, which is generated by the 3D-SAC, promotes colony growth and expression of Nanog and Oct4 in mESCs and blastocyst development of mouse embryos. These findings suggest that autonomous cell forces regulate embryonic stem cells fate determination and provide insight regarding the biomechanical regulation of embryonic development.

Fragmenting DNA into short pieces is an essential manipulation in many biological studies, ranging from genome sequencing to molecular diagnosis. Among various DNA fragmentation methods, microfluidic hydrodynamic DNA fragmentation has huge advantages especially in terms of handling small-volume samples and being integrated into automatic and all-in-one DNA analysis equipment. Despite the fast progress in experimental studies and applications, a systematic understanding of how DNA molecules are distributed, stretched and fragmented in a confined microfluidic field is still lacking. In this work, we investigate the extension and fragmentation of DNA in a typical contractive microfluidic field, which consists of a shear flow-dominated area and an elongational flow-dominated area, using the Brownian dynamics-computational fluid dynamics method. Our results show that the shear flow at the straight part of the microfluidic channel and the elongational flow at the contractive bottleneck together determine the performance of DNA fragmentation. The average fragment size of DNA decreases with the increase of the strain rate of the elongational flow, and the upstream shear flow can significantly precondition the conformation of DNA to produce shorter and more uniform fragments. A systematic study of the dynamics of DNA fragmentation shows that DNA tends to break at the mid-point when the strain rate of elongational flow is small, and the breakage point largely deviates from the midpoint as the strain rate increases. Our simulation of the thorough DNA fragmentation process in a realistic microfluidic field agrees well with experimental results. We expect that our study can shed new light on the development of future microfluidic devices for DNA fragmentation and integrated DNA analysis devices.

Silk is a widely available, edible, biocompatible, and environmentally sustainable natural material. Particulate matter (PM) pollution has drawn considerable attention because it is a serious threat to public health. Herein, we report a human-friendly silk nanofiber air filter, which exhibits superior filtration efficiency for both PM 2.5 and submicron particles with obviously low pressure drop and low basis weight compared to typical commercial microfiber air filters. Additionally, other functions such as antibacterial activity could be easily integrated into the silk nanofiber air filters, enabling the fabrication of multifunctional air filters. All the above characteristics, combined with the natural abundance and biocompatibility of silk, suggest a great potential for the use of silk nanofibers as air filters, especially as comfortable and personal air purifiers.

"清华学堂人才培养计划"作为国家"拔尖计划"的组成部分,经历了7年的改革与实践,"领跑者"理念初见成效。但同时也需要探索进一步上升和提高的空间,激励和引导学生追求卓越、超越自我。本文在简要分析国际上高水平大学荣誉学位项目经验的基础上,对清华荣誉学位的定位与钱学森力学班荣誉学位项目构建的指导原则、荣誉学位方案设计和实施等进行了较为详细的阐述。荣誉学位是对"领跑者"理念的深化。

Probing oriented bacterial cell growth on the nanoscale: A novel open-top micro-channel is developed to facilitate the AFM imaging of physically trapped but freely growing bacteria. The growth curves of individual Escherichia coli cells with nanometer resolution and their kinetic nano-mechanical properties are quantitatively measured.

Arrays of living bacteria were printed on agarose substrate with cellular resolution using elastomeric stamps with a high aspect ratio generated by reverse in situ lithography (RISL). The printed bacteria reproduced the original stamp patterns with high fidelity and continued growing as in bulk culture. This methodology provides a simple route to any desired bacterial spatial 2D distribution and may be applied to screening as well as to studies of bacteria phenotypic variability, population dynamics, and ecosystem evolution.

To keep bacteria growing in a monolayer is important for studying the cellular dynamics of single cells in growing population. In this paper we report on a microfluidic system for long-term '2-Dimension' culture of bacteria, which allows the bacteria to grow freely in a micro-channel without forming multilayer structure. The culture environment is well controlled to be constant and it can be easily changed from one to another if necessary. This system offers a versatile platform for many research fields such as gene expression dynamics, nois-induced diversity between individuals and familial phylogenetics.

介绍以软光刻(soft-lithography)为主要手段的微加工技术制备应用于等电聚焦及高效液相色谱的PH值梯度微流芯片. 此种PH梯度芯片具有容易加工、可根据需要快速得到不同范围的PH值梯度、精度可控制、IEF与分离有机结合为一体、等电聚焦所需电场低、PH值梯度不随时间改变等优点,将在芯片中样品的制备、分离、分析将有广泛的应用.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTArtificial Lotus Leaf by NanocastingManhui Sun, Chunxiong Luo, Luping Xu, Hang Ji, Qi Ouyang, Dapeng Yu, and Yong ChenView Author Information Center for Microfluidics and Nanotechnology, Peking University, 100871 Beijing, PR China, School of Physics, Peking University, 100871 Beijing, PR China, and Ecole Normale Suéprieure, 24 rue Lhomond, 75231 Paris, France Cite this: Langmuir 2005, 21, 19, 8978–8981Publication Date (Web):August 16, 2005Publication History Received4 February 2005Revised22 July 2005Published online16 August 2005Published inissue 1 September 2005https://pubs.acs.org/doi/10.1021/la050316qhttps://doi.org/10.1021/la050316qbrief-reportACS PublicationsCopyright © 2005 American Chemical SocietyRequest reuse permissionsArticle Views7878Altmetric-Citations602LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Contact angle,Genetics,Hydrophobicity,Hysteresis,Liquids Get e-Alerts