Lab-on-PCB-based micro-cytometer for circulating tumor cells detection and enumeration

Impedance-based microfluidic cytometer has been introduced to provide a companion diagnostic platform in biological cells analysis. In the conventional way, microfluidic impedance cytometer requires accurately patterning metal electrodes in the corresponding location on silicon/glass substrate, which is expensive and time-consuming. In this short communication, we demonstrate a disposable impedance-based microfluidic cytometer above the commercially available printed circuit board (PCB) with pre-deposited copper electrode, which is reusable. In this experiment, red blood cells (RBCs) and mixture of RBCs, white blood cells (WBCs), and circulating tumor cells (CTCs) are utilized to test the function of the proposed device, which indicated that it can differentiate the WBCs and CTCs from the mixture of the three types of cells. After each sample test, the upper microfluidic cytometer is disposed which shows the great commercial potential in point-of-care test for clinical application.     

Disk-like hydrogel bead-based immunofluorescence staining toward identification and observation of circulating tumor cells

Assays toward analysis of rare heterogeneous cells among identical specimen raise a significant challenge in many cell biological studies and clinical diagnosis applications. In this work, we report a disk-like hydrogel bead-based stratagem for rare cell researches at single cell level after a facile microfluidic-based particle synthesis approach. Cells of interested can be encapsulated into alginate droplets which are subsequently solidified into disk-like calcium alginate hydrogel beads and the bead size and cell number inside can be precisely controlled. Due to stability, permeability and disk-like shape of calcium alginate beads, cells immobilized in the disk-like beads can be treated with different chemicals with limited mechanical or fluidic operation influences and observed without distortion comparing with conventional methods or droplet microfluidic methods. Identification of circulating tumor cells, related to early-stage cancer diagnosis, is targeted to demonstrate the potential of our technique in rare cell analysis. This hydrogel bead-based stratagem is performed in immunofluorescence staining treatment and observation of cancer cells from normal hematological cells in blood sample. This method would have a great potential in single cell immobilization, manipulations and observation for biochemical cellular assays of rare cells.     

Isolation and retrieval of circulating tumor cells on a microchip with double parallel layers of herringbone structure

Isolation of the extremely rare circulating tumor cells (CTCs) from peripheral blood has become an effective tool for monitoring and staging tumor development, based on which the therapeutic efficacy can be evaluated. Many techniques have been developed for CTC isolation and enumeration. However, isolation and detection of CTCs with high sensitivity remains a challenging work, and there still exists an urgent demand to retrieve tumor cells after isolation for further molecular and cellular analyses. Herein, we report a dual-functional microchip with double parallel layers of herringbone structure. CTC isolation and retrieving can be simply achieved based on the reversible conjugation with anti-EpCAM modified on the interior channel surface. Specifically, two major strategies were engaged to improve the CTC isolation based on the synergistic effect of significantly increased functional surface area and local microvortex mixing. This approach could achieve CTC isolation efficiency of 75% on average and the detection limit down to 10 cells mL^?1. Furthermore, CTC retrieving rate was found at 73.4%. Therefore, the present method has a good potential for quantitation and retrieving CTCs with high efficiency for precise cancer diagnosis and subsequent cellular and molecular analyses.     

Isolation and elution of Hep3B circulating tumor cells using a dual-functional herringbone chip

Circulating tumor cells (CTCs), which are derived from primary tumor and circulate to secondary site, are regarded as the cause of metastasis. Many methods have been applied for CTC isolation and enumeration so far. However, it remains a challenge to effectively elute the captured cells from the device for further cellular and biomolecular analyses. In this paper, we fabricate a dual-functional herringbone chip to achieve both CTC capture and elution based on the immunoassay of epithelial cell adhesion molecule antigen expressed on the surface of human liver cancer cell line Hep3B. The results show that the capture limit of Hep3B cells can reach as low as 3 cells per ml with capture efficiency over 50 % on average. On the other hand, the elution rate of more than 50 % of the captured Hep3B cells can be achieved for cell density ranging from 5 to 2 × 10³/ml. It demonstrates that this herringbone chip exhibits excellent dual functions with high capture efficiency and considerable elution rate, indicating its promising capability for clinical assay in cancer diagnosis.     

Arrays of high-aspect ratio microchannels for high-throughput isolation of circulating tumor cells (CTCs)

Microsystem-based technologies are providing new opportunities in the area of in vitro diagnostics due to their ability to provide process automation enabling point-of-care operation. As an example, microsystems used for the isolation and analysis of circulating tumor cells (CTCs) from complex, heterogeneous samples in an automated fashion with improved recoveries and selectivity are providing new opportunities for this important biomarker. Unfortunately, many of the existing microfluidic systems lack the throughput capabilities and/or are too expensive to manufacture to warrant their widespread use in clinical testing scenarios. Here, we describe a disposable, all-polymer, microfluidic system for the high-throughput (HT) isolation of CTCs directly from whole blood inputs. The device employs an array of high aspect ratio (HAR), parallel, sinusoidal microchannels (25 × 150 μm; W × D; AR = 6.0) with walls covalently decorated with anti-EpCAM antibodies to provide affinity-based isolation of CTCs. Channel width, which is similar to an average CTC diameter (10–20 μm), plays a critical role in maximizing the probability of cell/wall interactions and allows for achieving high CTC recovery. The extended channel depth allows for increased throughput at the optimized flow velocity (2 mm/s in a microchannel); maximizes cell recovery, and prevents clogging of the microfluidic channels during blood processing. Fluidic addressing of the microchannel array with a minimal device footprint is provided by large cross-sectional area feed and exit channels poised orthogonal to the network of the sinusoidal capillary channels (so-called Z-geometry). Computational modeling was used to confirm uniform addressing of the channels in the isolation bed. Devices with various numbers of parallel microchannels ranging from 50 to 320 have been successfully constructed. Cyclic olefin copolymer (COC) was chosen as the substrate material due to its superior properties during UV-activation of the HAR microchannels surfaces prior to antibody attachment. Operation of the HT-CTC device has been validated by isolation of CTCs directly from blood secured from patients with metastatic prostate cancer. High CTC sample purities (low number of contaminating white blood cells) allowed for direct lysis and molecular profiling of isolated CTCs.     

Snort报文捕获机制的研究与改进

在对Snort系统的报文捕获机制进行研究的同时,针对Snort在高速网络上使用libpcap进行报文捕获的缺点提出了一种基于Sampleandhold采样算法的改进机制,提高了Snort系统在高速网络链路上检测异常/入侵活动的效率。     

片上协同网络和电磁协同效应感知的智能传感器

为了提高传感器的功能集成、扩展应用类型和保障电磁兼容,提出了一种基于片上协同网络和电磁协同效应感知的智能传感器.针对传感器节点的复用性、多用型和高效系统执行力,设计了单节点部署阵列式多传感器、多核和多天线设备的片上协同网络,并通过动态映射解决了片上通信和阵列设备间电磁干扰问题;在分析符号出错率、电磁协同效应的硬件发生率的基础上,通过逻辑协同控制传感器片上网络中的电磁协同效应,设计出了具有动态分层差异特性自适应控制符号传递和融合处理的智能传感器.实验结果表明:所设计的智能传感器数据采集误差小于0.1％,并带来了25％的工作延迟增益,不仅提高了数据精度而且改善了实时性.     

一种光学式运动捕捉系统下的物体运动数据捕捉方法研究

多相机视觉运动捕捉系统能通过捕捉标记点的空间坐标来获得运动物体的运动学参数,文中提出了一种基于多相机运动捕捉系统下的通用物体运动数据捕捉方法;首先根据3个标记点组成固定模型获取物体运动过程中对应标记点的瞬时坐标,然后通过向量法求解出被测物体在运动过程中各采集点对应的物体位姿,然后通过卡尔曼滤波方法消除运动捕捉过程中的系统和环境误差的影响,获得平滑的物体位姿运动轨迹,并根据滤波数据计算出物体在各采集点对应的速度、加速度、角速度、角加速度;最后基于协作机器人进行物体的运动数据捕捉实验,验证了所提出物体运动数据捕捉方法的正确性。     

通用可组合安全计算的信任模型研究

通用可组合（UC）安全计算的存在性需要刻画某种基础假定的信任模型的支持。针对国内对于UC安全计算的信任模型研究甚少的现状,研究了UC安全性的本质要求及其对UC安全计算的限制,得出了使用这些信任模型的根本原因,进而分析了国外用来刻画这些基础假定的信任模型的设计原理,比较了它们的异同和优缺点,并展望了未来的研究方向。     

HoneyPot终端信息捕获技术研究与实现

本文从终端输入的工作机理出发,详细介绍了各种基于内核的信息捕获技术,为HoneyPot的构建提供了较为全面的信息捕获的解决方案.     

The effect of parameter variation on the periodic oscillations in a non-linear system†

The effect of parameter variation on the periodic oscillations in a non-linear control system is discussed analytically and the concept of root-locus has been introduced to analyse the different dominating modes of oscillation. The theoretical formulation is based on the fact that the transient behaviour of a non-linear system, in the vicinity of the steady-state oscillation, is described by a linear differential equation with periodic coefficients.     

Maskless writing of microfluidics: Rapid prototyping of 3D microfluidics using scratch on a polymer substrate

We present a new rapid prototyping method designed for simple fabrication of 3D microfluidics using a maskless direct writing technique on polymer substrates. The entire process is enabled by a commercial cutter plotter with 10 μm resolution precision and high speed. A CAD design of top and bottom microstructures is directly written on a polymer substrate using a cutter plotter after setting up the suitable force. The smallest channel width of 20 μm was obtained with the minimum force and 100 μm from the maximum. Also the written depth increased linearly with force from 30 to 130 μm. Several 3D microfluidic devices are demonstrated using a maskless writing technique. The entire fabrication process from CAD layout to a final 3D device can be completed in 30 min outside the clean room facilities.     

Microvalve and liquid membrane double-controlled integrated microfluidics for observing the interaction of breast cancer cells

The methodical development of cell biology has resulted in significant advancements in the study of breast tumors. However, the dynamic investigation of the self-seeding process remains largely out of reach. In the present study, we describe a microvalve and liquid membrane double-controlled integrated microfluidic device that provides for the versatile assessment of breast tumor cell invasion dynamics. The liquid membrane formation was first optimized to obtain a high level of control, and was then applied to different types of homotypic and heterotypic cell seeding with precise selective positioning for monoculture and coculture. Using this device, the interaction between breast cancer cells MDA231-LM2 and MDA-MB231 was successfully observed to investigate self-seeding dynamics, including migration, infiltration, and coexistence. The results quantitatively demonstrate the mutual signal-induced attraction between MDA-MB231 and MDA231-LM2 cells, as well as the progressive infiltration of MDA231-LM2 cells into the MDA-MB231 cell population. These results are valuable in the development of spatiotemporal-controlled microfluidic systems and to many microscale-based biological and diagnostic studies involving cell growth, cell differentiation, cell interaction, and cell signal.     

时间尺度与选择倾向性协同作用下的演化博弈模型

针对合作行为的涌现与维持问题，基于演化博弈理论和网络理论，提出了一种促进合作的演化博弈模型。该模型同时将时间尺度、选择倾向性引入到演化博弈中。在初始化阶段，根据持有策略的时间尺度将个体分为两种类型：一种个体在每个时间步都进行策略更新；另一种个体在每一轮博弈后，以某种概率来决定是否进行策略更新。在策略更新阶段，模型用个体对周围邻居的贡献来表征他的声誉，并假设参与博弈的个体倾向于学习具有较好声誉邻居的策略。仿真实验结果表明，所提出的时间尺度与选择倾向性协同作用下的演化博弈模型中，合作行为能够在群体中维持；惰性个体的存在不利于合作的涌现，但是个体的非理性行为反而能够促进合作。     

基于人物角色的产品用户需求获取方法研究

为了使产品设计能深入满足用户的真实需求,在设计开发前期有效准确获取用户需求就变得十分关键。提出了一种基于人物角色模型的产品用户需求获取的新方法。通过场景细分确定典型用户,结合5W2H法提炼构建用户人物角色模型,通过KJ法对人物角色模型中提炼的用户需求进行聚类,得到典型用户需求指标体系。使用改进后的主观赋权法确定参数的权重,加权各方案并比较最终确定用户需求。并以无线移动终端产品造型设计为例进行说明。     

基于ARMLinux的图像采集与解码的实现

以S3C2440和ARMLinux操作系统为基础,研究了视频图像的采集与解码的实现方法.对Linux下的视频采集技术进行了分析,介绍了Video4Linux编程接口的使用方法,以使用USB摄像头采集图像为例,将采集到的JPEG格式的图像数据利用赫夫曼解码及反离散余弦变换等方法,将其解码为RGB格式的图像,最终在LCD上显示.实现了具有视频采集、软件图像解码及显示功能的模块,可以应用到实际中.     

循环肿瘤细胞分离液路控制系统分析优化

针对患者日益增长的体外诊断需求、个性化治疗需求以及提早发现癌症的需求,利用循环肿瘤细胞(CTC)与正常细胞物理特性的不同,通过微孔滤膜与相应的分离富集液路,实现特异细胞与正常细胞的物理分离。利用Fluent软件对液路压力情况进行仿真分析。针对在液体流动过程中,微孔滤膜因血液成分堵塞滤孔导致孔隙率降低,进而造成微孔滤膜承受的压力进入不合理区间,甚至滤膜堵死导致破裂的情况,提出一种一维模糊控制规则,可以使微孔滤膜的压力稳定在一个合理区间内。     

基于USB总线的高速视频采集系统设计

提出了一种基于视频解码芯片ADV7183B和USB2.0总线技术的高速视频采集系统的设计方案,该方案利用FPGA实现视频数据流的收发时序,通过USB接口芯片CY7C68013与主机进行交互通信。本文详细介绍了该视频采集系统的硬件结构、软件设计和工作流程。     

The effect of global extrapolation on the phase-lag of symmetric methods for solving periodic initial value problems

The effects are discussed of two-grid global extrapolation procedures on the phase-lags of convergent numerical methods for solving periodic initial value problems.

The procedure is tested on two methods applied to two problems from the literature, one nonlinear the other linear, and the effects of the extrapolation are examined by comparing corresponding zeros of the waves generated by the theoretical and computed solutions.

Extensions to three- and four-grid extrapolation procedures are outlined in an Appendix.     

Analyzing Effect of Demand Rate on Safety of Systems with Periodic Proof-tests

Quantitative safety assessment of safety systems plays an important role in decision making at all stages of system lifecycle, i.e.,design,deployment and phase out.Most safety assessment methods consider only system parameters,such as configuration,hazard rate,coverage,repair rate,etc.along with periodic proof-tests (or inspection).Not considering demand rate will give a pessimistic safety estimate for an application with low demand rate such as nuclear power plants,chemical plants,etc.In this paper,a basic model of IEC 61508 is used.The basic model is extended to incorporate process demand and behavior of electronic- and/or computer-based system following diagnosis or proof-test.A new safety index,probability of failure on actual demand (PFAD) based on extended model and demand rate is proposed.Periodic proof-test makes the model semi-Markovian,so a piece-wise continuous time Markov chain (CTMC) based method is used to derive mean state probabilities of elementary or aggregated state.Method to determine probability of failure on demand (PFD) (IEC 61508) and PFAD based on these state probabilities are described.In example,safety indices of PFD and PFAD are compared.