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Enhancing single-cell encapsulation in droplet microfluidics with fine-tunable on-chip sample enrichment

Microsystems & Nanoengineering 2024年第1期10卷 149-160页

作者： Tao Tang Hao Zhao shaofei shen Like Yang Chwee Teck Lim Department of Biomedical Engineering National University of Singapore117583 SingaporeSingapore Integrative Sciences and Engineering Programme NUS Graduate SchoolNational University of Singapore119077 SingaporeSingapore Shanxi Key Lab for Modernization of TCVM College of Life ScienceShanxi Agricultural UniversityTaiguShanxi 030801China Institute for Health Innovation&Technology National University of Singapore117599 SingaporeSingapore Mechanobiology Institute National University of Singapore117411 SingaporeSingapore Institute for Digital Molecular Analytics and Science Nanyang Technological University636921 SingaporeSingapore

Single-cell encapsulation in droplet microfluidics is commonly hindered by the tradeoff between cell suspension density and on-chip focusing performance.In this study,we introduce a novel droplet microfluidic chip to overcome this challenge.The chip comprises a double spiral focusing unit,a flow resistance-based sample enrichment module with fine-tunable outlets,and a crossflow droplet generation unit.Utilizing a low-density cell/bead suspension(2×10^(6) objects/mL),cells/beads are focused into a near-equidistant linear arrangement within the double spiral microchannel.The excess water phase is diverted while cells/beads remain focused and sequentially encapsulated in individual droplets.Focusing performance was assessed through numerical simulations and experiments at three flow rates(40,60,80μL/min),demonstrating successful focusing at 40 and 80μL/min for beads and cells,respectively.In addition,both simulation and experimental results revealed that the flow resistance at the sample enrichment module is adjustable by punching different outlets,allowing over 50%of the aqueous phase to be removed.YOLOv8n-based droplet detection algorithms realized the counting of cells/beads in droplets,statistically demonstrating single-cell and bead encapsulation rates of 72.2%and 79.2%,respectively.All the results indicate that this on-chip sample enrichment approach can be further developed and employed as a critical component in single-cell encapsulation in water-in-oil droplets.

关键词： beads outlet sample

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Construction of multiple concentration gradients for single-cell level drug screening

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Microsystems & Nanoengineering 2023年第2期9卷 193-203页

作者： shaofei shen Fangjuan Zhang Yali Zhang Yi Li Yanbing Niu Long Pang Jinyi Wang Shanxi Key Lab for Modernization of TCVM College of Life ScienceShanxi Agricultural UniversityTaiguShanxi 030801China School of Basic Medical Science Xian Medical UniversityXianShaanxi 710021China College of Chemistry and Pharmacy Northwest A&F UniversityYanglingShaanxi 712100China

Isolation and manipulation of single cells play a crucial role in drug screening.However,previously reported single-cell drug screening lacked multiple-dose concentration gradient studies,which limits their ability to predict drug performance accurately.To solve this problem,we constructed a multiconcentration gradient generator in which a Tai Chi-spiral mixer can accelerate solution mixing in a short time and produce a linear concentration gradient.Later,a gradient generator combined with a single-cell capture array was adopted to investigate the effects of single or combined doses of 5-fluorouracil and cisplatin on human hepatoma cells and human breast carcinoma cells(at the single-cell level).The results showed that both drugs were effective in inhibiting the growth of cancer cells,and the combination was more effective for human hepatoma cells.In addition,the relationship between the biomechanical heterogeneity(e.g.,deformability and size)of tumor cells and potential drug resistance at the single-cellevel was investigated,indicating that small and/or deformable cells were more resistant than large and/or less deformable cells.The device provides a simple and reliable platform for studying the optimal dosage of different drug candidates at the single-cell level and effectively screening single-agent chemotherapy regimens and combination therapies.

关键词： dosage doses drugs

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基于力学性能指标与耐久性能指标联合的夯土改性配比优化设计方法

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土木工程学报 2024年第5期57卷 1-14页

作者：沈圣孙宇王耀姜绍飞张鹰付绪峰王鸣福州大学福建福州3501082 上海市建筑装饰工程集团有限公司上海2000403 中建海峡建设发展有限公司福建福州350015

素土强度低、耐久性差且各改性材料掺量往往由工匠凭经验大致确定,导致夯土表面时常容易开裂剥落,故应根据现场土质状况以及合理试验方法来设计夯土改性配比。现有研究大都局限于单一性能指标最优的配比,而现实中夯土既要考虑针对多项... 详细信息

素土强度低、耐久性差且各改性材料掺量往往由工匠凭经验大致确定,导致夯土表面时常容易开裂剥落,故应根据现场土质状况以及合理试验方法来设计夯土改性配比。现有研究大都局限于单一性能指标最优的配比,而现实中夯土既要考虑针对多项力学性能指标与耐久性能指标的同步优化,还要考虑不同地域与气候条件下各指标的重要性不同。另外,现有研究仅能确定若干预设配比中的最优组,而非改性材料预设掺量范围内的最优配比。为此,文章提出一种基于力学性能指标与耐久性能指标联合的夯土改性配比优化设计方法,其包括:(1)土料选用原则与土质鉴定方法;(2)考虑夯土多性能指标的综合赋权方法;(3)基于加权评分和回归分析的夯土改性配比综合比选与优化方法。文章方法通过调整指标权重筛选出适应指标重要性不同时的夯土改性配比,并通过优化设计获得各改性材料预设掺量范围内的最优配比。最后通过设计实例证明了文章方法的确可得到最优的夯土改性配比。

关键词：夯土配比多性能指标权重系数优化设计

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Truthfully coordinating participation routes in informative participatory sensing

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Science China(Information Sciences) 2021年第12期64卷 132-146页

作者： shaofei CHEN Dengji ZHAO Alexandros ZENONOS Jing CHEN Lincheng shen College of Intelligence Science and Technology National University of Defense Technology School of Information Science and Technology ShanghaiTech University School of Electronics and Computer Science University of Southampton

Participatory sensing is a promising approach with which people contribute sensory information to form a body of knowledge. In practice, people may have different ways to engage in a participatory sensing campaign. For example, there are several possible routes from a participant’s home to her office, where a route can be seen as a set of space-temporal coordinates, and measurements can be taken at these coordinates. To coordinate participation routes to collect more valuable information with a limited number of participants,a further concept, informative participatory sensing(IPS) has been developed recently. However, existing IPS systems lack incentive mechanisms to fight against the strategic behaviours of self-interested users.Hence, we propose a formal model of IPS where a service provider can coordinate individual schedules of self-interested participants. As the problem of informative path coordination is NP-hard, the well-known mechanism, Vickrey-Clarke-Groves(VCG) will be computationally inefficient to solve our problem. Given this, we design a sequentially sorting mechanism(SSM) for the model to allocate the schedules and determine the bonuses for these participants, and we then theoretically prove that SSM is computationally efficient,individually rational, profitable and truthful. Furthermore, we empirically evaluate our route allocation method in simulations and show that it significantly outperforms several benchmark approaches.

关键词： coordinating participation routes Coordinating participation routes informative participatory sensing incentive mechanism computationally efficient

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Measuring the built environment of green transit-oriented development:A factorcluster analysis of rail station areas in Singapore

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Frontiers of Architectural Research 2021年第3期10卷 652-668页

作者： shaofei Niu Ang Hu Zhongwei shen Ying Huang Yanchuan Mou College of Architecture and Environment Sichuan UniversityChengdu610065China School of Architecture and Design Southwest Jiaotong UniversityChengdu611756China Faculty of Architecture and Urban Planning Key Laboratory of New Technology for Construction of Cities in Mountain AreaChongqing UniversityChongqing400030China

Green transit-oriented development(TOD)is an evolution of the TOD theory,influenced by sustainable development and green urbanism.This advancement expands the environmental and ecological dimensions of conventional TOD.However,relevant research has only just started,particularly in combination with high-density cities in Asia.This study measures the built environment of Green TOD and identifies the key factors and characteristics of the Green TOD built environment.An evaluation method for the Green TOD built environment is developed on the basis of the 5D(density,diversity,design,destination,and distance)built environment framework and combined with green urbanism theories.Data from 23 rail station areas in Singapore were collected and analyzed using factor and cluster analysis.Five factors,namely,neighborhood spatial form factor,facility completeness factor,open space factor,high-density mixed land-use factor,and walking amenity factor,are extracted.Twentythree station areas are classified into five clusters.The characteristics and optimization strategies of each cluster are analyzed on the basis of the statistical and graphical analyses.This research displays the characteristics and typology of the Green TOD built environment in an empirical way and offers a foundation for further research in diverse urban contexts.

关键词： Green TOD Built environment TOD typology Urban analysis GIS

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Global brown carbon emissions from combustion sources

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Environmental Science and Ecotechnology 2022年第4期12卷 46-53页

作者： Rui Xiong Jin Li Yuanzheng Zhang Lu Zhang Ke Jiang Huang Zheng shaofei Kong Huizhong shen Hefa Cheng Guofeng shen Shu Tao Laboratory for Earth Surface Processes College of Urban and Environmental SciencesPeking UniversityBeijing100871China Department of Environmental Science and Technology School of Environmental StudiesChina University of GeosciencesWuhan430074China School of Environmental Sciences and Engineering Southern University of Science and TechnologyShenzhen518055China

Light-absorbing organic carbon(OC),sometimes known as Brown Carbon(BrC),has been recognized as an important fraction of carbonaceous aerosols substantially affecting radiative forcing.This study firstly developed a bottom-up estimate of global primary BrC,and discussed its spatiotemporal distribution and source contributions from 1960 to 2010.The global total primary BrC emission from both natural and anthropogenic sources in 2010 was 7.26(5.98-8.93 as an interquartile range)Tg,with 43.5%from anthropogenic sources.High primary BrC emissions were in regions such as Africa,South America,South and East Asia with natural sources(wild fires and deforestation)contributing over 70%in the former two regions,while in East Asia,anthropogenic sources,especially residential solid fuel combustion,accounted for over 80%of the regional total BrC emissions.Globally,the historical trend was mainly driven by anthropogenic sources,which increased from 1960 to 1990 and then started to decline.Residential emissions significantly impacted on emissions and temporal trends that varied by region.In South and Southeast Asia,the emissions increased obviously due to population growth and a slow transition from solid fuels to clean modern energies in the residential sector.It is estimated that in primary OC,the global average was about 20%BrC,but this ratio varied from 13%to 47%,depending on sector and region.In areas with high residential solid fuel combustion emissions,the ratio was generally twice the value in other areas.Uncertainties in the work are associated with the concept of BrC and measurement technologies,pointing to the need for more studies on BrC analysis and quantification in both emissions and the air.

关键词： Brown carbon Emission inventory Historical changes Spatial distribution

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Landscape Design of Urban Rail Transit Complex Based on the Concept of Sustainable Development

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Journal of Landscape Research 2016年第4期8卷 21-26页

作者： NIU shaofei shen Zhongwei School of Architecture and Design Southwest Jiaotong University

On the basis of current development of urban rail transit complex in China,this paper proposed that it is necessary to build a complete landscape design system of urban traffic complex.Combined with the concept of sustainable urban landscape design,this paper explored landscape design of urban rail transit complex from the macroscopic,mesocopic and microscopic perspective,and analyzed many design cases to provide references for the sustainable landscape design of urban rail transit complex in China.

关键词： Urban rail transit complex Sustainable concept Landscape desig

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仿生树叶模型的制作及在琼脂糖微流控芯片中的应用

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高等学校化学学报 2022年第11期43卷 53-58页

作者：王方圆张奋娴李毅高建华牛颜冰申少斐山西农业大学生命科学学院中兽医药现代化山西省重点实验室太谷030801

树叶的脉序可以更好模拟人体血管微环境,但以自然环境中树叶为模板进行实验存在一定的季节局限性;且不能保证每次实验所用树叶脉序形状相同,不易控制变量,且会对环境造成一定破坏.本文建立了一种简易的仿生树叶模型制作方法,并通过仿生... 详细信息

树叶的脉序可以更好模拟人体血管微环境,但以自然环境中树叶为模板进行实验存在一定的季节局限性;且不能保证每次实验所用树叶脉序形状相同,不易控制变量,且会对环境造成一定破坏.本文建立了一种简易的仿生树叶模型制作方法,并通过仿生模型构建了经济、易操作的琼脂糖微流控芯片.分别测定了芯片的一、二、三级脉序数目及尺寸,最大脉序尺寸值可达1038.02μm,最小脉序尺寸为36.32μm,宽度不一的通道构建为细菌趋化性实验提供了稳定可靠的梯度空间,对探索药物筛选、微生物利害等研究具有重要意义.

关键词：仿生微流控芯片趋化性

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勒让德多项式拟合IGS精密星历的算法改进

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全球定位系统 2022年第4期47卷 17-22页

作者：申少飞雷伟伟李振南河南理工大学测绘与国土信息工程学院河南焦作454003

国际GNSS服务(IGS)精密星历每隔15 min提供一次卫星坐标,为了提高定位精度,往往需要获取任意时刻的卫星位置.对IGS精密星历进行插值和拟合是获得连续历元卫星坐标常用的方法.运用改进的勒让德多项式算法拟合卫星轨道坐标,并与常规算法... 详细信息

国际GNSS服务(IGS)精密星历每隔15 min提供一次卫星坐标,为了提高定位精度,往往需要获取任意时刻的卫星位置.对IGS精密星历进行插值和拟合是获得连续历元卫星坐标常用的方法.运用改进的勒让德多项式算法拟合卫星轨道坐标,并与常规算法进行比较,结果表明:常规算法仅在拟合阶数较低时能保持较高的精度.在拟合时段为6 h时,LU分解(LU Decomposition)法与奇异值分解(SVD)法对奇异矩阵求解时均能保持较高的精度,而在拟合时段为12 h时,SVD分解法是对条件数较低的矩阵B进行分解求得多项式系数矩阵C,从而避免了病态矩阵产生的误差,因此仍能保持较高的精度.在高阶拟合时,SVD分解法无论是在精度还是稳定性方面均优于LU分解法和常规算法,优势明显.

关键词：勒让德多项式拟合卫星轨道坐标拟合 LU分解(LU Decomposition)法奇异值分解(SVD)法病态矩阵

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两种北斗卫星精密星历外推方法的精度分析

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测绘通报 2023年第9期 12-17,69页

作者：申少飞雷伟伟李振南马晨阳河南理工大学测绘与国土信息工程学院河南焦作454003 中国科学院精密测量科学与技术创新研究院湖北武汉430077

国际全球卫星导航系统服务(IGS)中心只提供当天00:00:00—23:45:00的精密星历数据,若要获取当天完整的星历数据,往往采用坐标外推的方法得到23:45:00—24:00:00时段的星历数据。本文采用三角函数插值法和广义延拓逼近法对一段时间不同... 详细信息

国际全球卫星导航系统服务(IGS)中心只提供当天00:00:00—23:45:00的精密星历数据,若要获取当天完整的星历数据,往往采用坐标外推的方法得到23:45:00—24:00:00时段的星历数据。本文采用三角函数插值法和广义延拓逼近法对一段时间不同类型和不同时间间隔的北斗卫星精密星历轨道坐标进行外推。结果表明,GEO卫星精密星历轨道坐标外推精度优于IGSO卫星和MEO卫星;两种外推方法对于5 min时间间隔精密星历外推精度明显高于15 min时间间隔精密星历,且三角函数插值法外推精度优于广义延拓逼近法1~2个数量级。因此,在对北斗卫星精密星历进行轨道坐标外推时,可以优先采用精度更高的三角函数插值法和使用5 min时间间隔的星历数据进行外推计算。

关键词：北斗卫星精密星历轨道坐标外推三角函数插值广义延拓逼近法最优精度分析

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