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Advances in atomic force microscopy for single-cell analysis

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Nano Research 2019年第4期12卷 703-718页

作者： Mi Li ning xi Yuechao Wang Lianqing Liu State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China Institutes for Robotics and Intelligent Manufacturing Chinese Academy of Sciences Shenyang 110016 China Department of Industrial and Manufacturing Systems Engineering The University of Hong Kong Hong Kong 999077 China

Single-cell analysis has been considered as a promising way to uncover the underlying mechanisms guiding the mysteries of life activities, which con siderably complements traditio nal en semble assays and yields novel in sights into cell biology. The adve nt of atomic force microscopy (AFM) provides a potent tool for investigati ng the structures and properties of n ative biological samples at the micro/na no scale un der near-physiological conditions, which promotes the studies of single-cell behaviors. In the past decades, AFM has achieved great success in single-cell observation and manipulation for biomedical applications, demonstrating the excellent capabilities of AFM in addressing biological issues at the single-cell level with unprecedented spatiotemporal resolution. In this article, we review the recent advances in single-cell analysis that has been made with the utilization of AFM, and provide perspectives for future progression.

关键词： atomic force microscopy single-cell analysis cellular morphology cellular mechanics cellular manipulation

CToMP: a cycle-task-oriented memory protection scheme for unmanned systems

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Science China(Information Sciences) 2024年第6期67卷 399-417页

作者： Chengyan MA ning xi Di LU Yebo FENG Jianfeng MA School of Cyber Engineering Xidian University School of Computer Science and Technology Xidian University Department of Computer and Information Science University of Oregon

Memory corruption attacks(MCAs) refer to malicious behaviors of system intruders that modify the contents of a memory location to disrupt the normal operation of computing systems, causing leakage of sensitive data or perturbations to ongoing processes. Unlike general-purpose systems, unmanned systems cannot deploy complete security protection schemes, due to their limitations in size, cost and *** in unmanned systems are particularly difficult to defend against. Furthermore, MCAs have diverse and unpredictable attack interfaces in unmanned systems, severely impacting digital and physical sectors. In this paper, we first generalize, model and taxonomize MCAs found in unmanned systems currently, laying the foundation for designing a portable and general defense approach. According to different attack mechanisms,we found that MCAs are mainly categorized into two types — return2libc and return2shellcode. To tackle return2libc attacks, we model the erratic operation of unmanned systems with cycles and then propose a cycle-task-oriented memory protection(CToMP) approach to protect control flows from tampering. To defend against return2shellcode attacks, we introduce a secure process stack with a randomized memory address by leveraging the memory pool to prevent Shellcode from being executed. Moreover, we discuss the mechanism by which CTo MP resists the return-oriented programming(ROP) attack, a novel variant of return2libc attacks. Finally, we implement CTo MP on CUAV V5+ with Ardupilot and Crazyflie. The evaluation and security analysis results demonstrate that the proposed approach CTo MP is resilient to various MCAs in unmanned systems with low footprints and system overhead.

关键词： unmanned system memory corruption attack memory protection system security randomized memory address

Design and implementation of precise position controller of active probe of atomic force microscopy for nanomanipulation

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Chinese Science Bulletin 2008年第13期53卷 2090-2096页

作者： HAO LiNa ZHANG JiangBo xi ning School of Mechanical Engineering & Automation Northeastern University Shenyang 110004 China Department of Electrical and Computer Engineering Michigan State University East Lansing MI 48824 USA

Efficiency and accuracy of AFM-based nanomanipulation are still major problems to be solved,due to the nonlinearities and uncertainties,such as drift,creep,hysteresis,etc. The deformation of cantilevers caused by manipulation force is also one of the most major factors of nonlinearities and uncertainties. It causes difficulties in precise control of the tip position and causes the tip to miss the position of the object. In order to solve this problem,the traditional approach is to use a rigid cantilever. However,this will significantly reduce the sensitivity of force sensing during manipulation,which is essential for achieving an efficient and reliable nanomanipulation. In this paper,a kind of active AFM probe has been used to solve this problem by directly controlling the cantilever’s flexibility or rigidity during manipu-lation. Based on Euller-Bernoulli Model,a kind of controller of the active probe employing Peri-odic-Output-Feedback(POF)law is implemented. The results of simulation and experiments have demonstrated that this theoretical model and POF controller are suitable for precise position control of nanomanipulation.

关键词：活化探针原子显微镜周期输出反馈控制原子力

AFM based anodic oxidation and its application to oxidative cutting and welding of CNT

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Science China(Technological Sciences) 2009年第11期52卷 3149-3157页

作者： JIAO NianDong WANG YueChao xi ning DONG ZaiLi State Key Laboratory of Robotics Shenyang Institute of AutomationChinese Academy of SciencesShenyang 110016China Department of Electrical and Computer Engineering Michigan State UniversityEast Lansing 48824USA

Probe anodic oxidation by atomic force microscope (AFM) is one of the most important techniques in fabricating nano structures and devices. The technique was further studied in this paper. By analyzing the distribution of the electric field on substrate surface the dependence of oxide characters on field was discussed. The impacts of various parameters on oxide fabrication were experimentally studied. Based on these studies, we realized the oxidative cutting and welding of carbon nanotube (CNT) by the AFM based oxidation technique and provided a novel technique for the assembly and fabrication of CNT based nano devices.

关键词： anodic oxidation atomic force microscope nanofabrication cutting and welding carbon nanotube

Discriminative Word Alignment over Multiple Word Segmentations

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Chinese Journal of Electronics 2014年第2期23卷 263-270页

作者： xi ning DAI xinyu HUANG Shujian CHEN Jiajun State Key Laboratory for Novel Software Technology Department of Computer Science and TechnologyNanjing University

Conventional bilingual word alignment is conducted on sentence pairs with single word segmentation for languages such as Chinese, viz. Single-segmentationbased word alignment(SSWA). However, SSWA may run the risk of losing optimal word segmentation granularities or causing data sparseness in word alignment. This paper proposes Multiple-segmentation-based word alignment(MSWA). In MSWA, diverse and complementary knowledge in multiple word segmentations can be employed to lower the above risks in word alignment. Given k word segmentations of a Chinese sentence, a skeleton segmentation is firstly constructed. The alignment between the skeleton segmentation and the parallel English sentence is loglinearly modeled, where various features defined over multiple word segmentations are incorporated. The Viterbi alignment, the alignment with the highest score, is mapped back to k word alignments based on k segmentations respectively. Experimentally, MSWA outperformed SSWA on all k segmentations in both alignment quality and translation performance.

关键词： Natural language processing Word align-ment Multiple word segmentation Machine translation

Atomic force microscopy studies on cellular elastic and viscoelastic properties

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Science China(Life Sciences) 2018年第1期61卷 57-67页

作者： Mi Li Lianqing Liu ning xi Yuechao Wang State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China Department of Industrial and Manufacturing Systems Engineering The University of Hong Kong Hong Kong China

In this work, a method based on atomic force microscopy (AFM) approach-reside-retract experiments was established to simultaneously quantify the elastic and viscoelastic properties of single cells. First, the elastic and viscoelastic properties of normal breast cells and cancerous breast cells were measured, showing significant differences in Young’s modulus and relaxation times between normal and cancerous breast cells. Remarkable differences in cellular topography between normal and cancerous breast cells were also revealed by AFM imaging. Next, the elastic and viscoelasitc properties of three other types of cell lines and primary normal B lymphocytes were measured; results demonstrated the potential of cellular viscoelastic properties in complementing cellular Young’s modulus for discerning different states of cells. This research provides a novel way to quantify the mechanical properties of cells by AFM, which allows investigation of the biomechanical behaviors of single cells from multiple aspects.

关键词： atomic force microscopy cell mechanical properties viscoelastic properties Young's modulus relaxation time

Credit-based scheme for security-aware and fairness-aware resource allocation in cloud computing

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Science China(Information Sciences) 2017年第5期60卷 96-112页

作者： Di LU Jianfeng MA Cong SUN xindi MA ning xi School of Computer Science Xidian University

Cloud computing systems include different types of participants with varied requirements for resources and multiple tasks; these varying requirements must be considered in the design of fairness-aware resource allocation schemes for better resources sharing. However, some participants may be malicious with a goal to damage the resource allocation fairness and increase their own utility. Hence, the resource scheduling policy must guarantee allocation fairness among the participants; further, it must ensure that fairness is not affected by the malicious usage of resources, that could cause resource exhaustion and lead to denial of service. In order to address this challenge, we propose a credit-based mechanism for resource allocation that will avoid the malicious usage of resources and, simultaneously, guarantee allocation fairness. In our scheme, a credit factor is introduced for each participant in order to evaluate the history of resource utilization and determine future resource allocation. Our model encourages a participant to release the occupied resources in timely manner after the completion of a task and imposes a punishment for malicious occupation of resources. We prove the fairness of our model and provide linear and variable gradient approaches to determine the credit factor for different scenarios. We simulate our model and perform experiments on a real cloud computing platform. The results prove the rationality, effectiveness and correctness of our approaches.

关键词： credit resource allocation security fairness cloud computing

A Method for Effective Population Transfer in U Vapor with Doppler Effect and Collision

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Chinese Physics Letters 1996年第8期13卷 590-593页

作者： ning xi-jing JING Chun-yang LIN Fu-cheng Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800

We proposed a method for effective population transfer in an atomic vapor with Doppler effect and *** this method,we have demonstrated that an efficient population transfer occurs in ^(238)U vapor produced in a hollow-cathode discharge tube.A numerical calculation with density matrix agrees well with our experimental result and indicates that the method can be used to raise the efficiency of atomic vapor isotope separation.

关键词： separation method collision

Soil Wetting Patterns and Water Distribution as Affected by Irrigation for Uncropped Ridges and Furrows

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Pedosphere 2015年第3期25卷 468-477页

作者： ZHANG Yong-Yong ZHAO xi-ning WU Pu-Te Linze Inland River Basin Research Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Key Laboratory of Eco-hydrology of Inland River Basin Chinese Academy of Sciences Institute of Water Saving Agriculture in Arid regions of China Northwest A&F University

The ridge-furrow tillage combined with furrow irrigation is being more widely applied and has been shown to be effective in the Loess Plateau of China. Accurate characterization of water infiltration behavior under ridge-furrow irrigation could provide guidelines and criteria for future irrigation system design and operation. Our objective was to investigate soil water behavior during ponding infiltration in a cross-sectional ridge-furrow configuration. Soil water movement within three different soil textures was tested by tracking the spatial and temporal soil water content(SWC) variations in a soil chamber. The two-dimensional transient flow initially transferred rapidly, but gradually decreased with elapsed infiltration time, approaching a stable flow after 90 min. A technical parameter equation incorporating the Philip equation was developed using the water balance method to accurately predict total applied water volume(TAWV). The wetting patterns moved outward in an elliptical shape. The wetted lateral and downward distances fitted using equations accounted for capillary and gravitational driving forces in variably wetted soil media. Increasing initial SWC resulted in an increase in wetted soil volume, which can also be caused by decreasing bulk density in a homogeneous soil. Higher water level produced greater wetted lateral distance and more irrigation uniformity. The wetted lateral distance was almost identical to the wetted depth in silty clay loam soil; hence ridge-furrow irrigation should be implemented in such finer-textured soils. The wetted soil volume differed markedly among different soil textures(hydraulic properties), demonstrating that these properties can largely determine soil water spreading patterns and distribution.

关键词： infiltration ridge-furrow tillage soil texture soil water content technical parameter equation wetted soil volume