多通道复合式光学成像系统中运动点目标的自动检测

单纯对单孔径光学成像系统的图像数据进行检测处理,来实现对运动点目标的自动检测和判别是非常困难的.本文根据多通道复合式光学成像系统多个通道视场有重叠的固有特点,建立了应用于该系统的运动点目标自动检测和判别方法.实际系统上测试证明了所设计检测方法有效地提高了运动点目标检测的概率,减少了误判和虚警,检测方法可行有效.     

双尺度疏油结构纳米通道滑移效应的研究

针对双尺度结构表面疏油特性的优异性,采用分子动力学的方法建立油液流体正十六烷烃分子模型,研究双尺度结构壁面润湿性影响下的纳米通道内流体的流动特性,通过对通道壁面亲疏油性下的双尺度结构的构建,与光滑壁面和单尺度壁面进行比较来探究双尺度纳米通道表面结构影响下油液流体在纳米通道内密度分布、速度分布、速度滑移和滑移长度的影响.模拟结果表明:对于亲油通道壁面,双尺度结构壁面亲油性明显加强,主流区域流体密度、流体速度和速度滑移都减小,甚至出现负滑移;而对于疏油通道壁面,双尺度分层结构能加强壁面的疏油性,通道内壁面形成稳定的气层使流体主流区域的密度增大,并且通道内流体的速度、速度滑移和滑移长度明显大于光滑和单尺度结构壁面.因此,纳米通道内双尺度结构能改变通道壁面的润湿性,并且能够加强流体在纳米疏油通道内的滑移减阻效应,为纳米通道内油液运输以及润滑薄膜减阻提供了设计基础.     

HeLa细胞突起中微丝束的纳米分辨荧光成像

在Matlab编程环境下模拟了单分子定位显微的纳米分辨成像,在传统实验参数条件下,对不同间隔分子带模型进行了模拟成像.模拟结果表明,单分子定位显微方法可以区分中心相隔20 nm的两个分子带.同时,也分析了不同像元大小对单分子定位精度的影响.此外,通过单分子定位显微方法在IX71倒置荧光显微镜上实现了纳米分辨,系统极限分辨率,即半高全宽为48 nm.在该系统上,获得了HeLa细胞突起中微丝束结构的纳米分辨图像.从重构获得的图像中可以看到微丝束的直径为75—200 nm.     

电场方向对一维断裂纳米通道连接处水桥结构的影响

电场影响纳米通道内的水分子的电偶极矩取向,进而影响纳米通道内的水分子的传输.为了有效发掘水分子在纳米通道内的传输特点,必须研究更复杂的纳米通道结构.最新一种构造复杂纳米通道的方式是构造断裂纳米通道.在研究断裂纳米通道内的水分子的动力学特点时,通常是在零电场或单一电场方向下进行的,电场方向对断裂纳米通道内的水分子的影响机理尚不明确,这制约了部分场控分子器件的设计.为了探究该问题,本文采用分子动力学模拟方法,系统研究了电场方向从0°变化到180°的过程中,电场方向对完整纳米通道以及断裂长度分别为0.2和0.4 nm的断裂纳米通道内的水分子的占据数、传输、水桥、电偶极矩偏向等性质的影响.结果表明,在1 V/nm的电场强度作用下,这三种纳米通道内的水分子的占据数、传输等差别主要集中在电场方向与管轴夹角为90°时,此时完整纳米通道内能形成稳定的水链,断裂长度为0.2 nm的纳米通道的连接处能形成不稳定的水桥,而断裂长度为0.4 nm的纳米通道的连接处不能形成水桥.此外,模拟发现当电场极化方向与管轴夹角为90°时,增大电场的强度,断裂纳米通道连接处的水桥更容易断裂.     

基于比色法和表面增强拉曼光谱双传感系统检测水中的芘

设计了一种基于AgNPs-AuNPs的核-卫星纳米结构检测水样中多环芳烃芘的比色和SERS双通道传感系统。首先将单巯基β-环糊精修饰到纳米金颗粒和纳米银颗粒的表面。受益于氧化态的四甲基联苯胺的触发,当体系中存在多环芳烃芘时,纳米颗粒会自组装形成AgNPs-pyrene-AuNPs的核-卫星结构。芘分子在其中充当分子桥的作用,拉近纳米粒子距离,使得纳米粒子发生一定的聚集。所以芘分子的个数直接影响AgNPs-pyrene-AuNPs的核-卫星结构数量,使溶液颜色发生变化,能够通过目测法建立溶液颜色与芘浓度的关系;组装形成的的核-卫星结构具有非常丰富的“热点”而表现出较强的表面增强拉曼光谱(SERS)活性,可通过SERS方法实现芘分子的高灵敏高特异检测。此结构可通过比色法和SERS方法实现水中芘的高灵敏高特异性检测。该方法可以在25 min内快速完成微量芘的检测,比色法对芘的检出限为3.4μmol·L^-1, SERS法的检出限为0.42μmol·L^-1。根据上述原理,基于AgNPs-PAHs-AuNPs核-卫星结构的SERS传感器可用来检测水样中的...     

用于大景深三维纳米分辨多分子追踪的衍射光学元件的设计制备和实验研究

发展能实时检测完整细胞内多个生物分子随时空变化的单分子探测和追踪技术, 对于研究生命过程的分子机理具有重要意义. 在变形光栅多阶成像和双螺旋点扩散函数成像方法的基础上, 基于波前编码的原理, 提出将二者优化结合, 获得全新的衍射光学元件, 该器件同时具有多重平面成像和双螺旋点扩散函数成像的功能, 旨在解决活细胞内单分子探测和追踪技术中的大景深探测难题. 设计和制备了该器件, 并基于该器件搭建了显微成像系统, 实验模拟证明该衍射光学元件同时可实现轴向12 μ的探测范围, 与理论设计结果相符合, 从而有效扩大了显微镜系统的景深, 证明了设计的可行性. 关键词： 多分子追踪 衍射光学元件 变形光栅 双螺旋点扩散函数     

应用于单分子测序的纳米微结构器件

基因测序技术是现代最为重要的生物医学研究手段之一,单分子测序技术作为最新一代测序技术被广泛研究,并形成了微纳制造、光电子、微流控和分子生物学等多学科的交叉探索和多种技术创新的有机结合.文章系统总结了应用于单分子测序的纳米微结构器件的原理和功能,重点阐述了零模波导器件和纳米孔器件在单分子测序中的作用以及制备工艺,从器件的角度提出了单分子测序技术所面临的挑战.     

基于FPGA的无创伤血液成分光谱采集系统设计

血液成分检测是健康诊断的重要手段,常规的血液成分检测采用抽血的方法,不仅给病人带来痛苦,还存在交叉感染的风险。近红外光谱技术是无创伤血液成分检测中的研究热点。为满足近红外无创伤血液成分检测仪器对其光谱数据采集系统提出的高速、多通道和高信噪比的要求,设计了一种基于现场可编程门阵列(FPGA)的高速、多通道光谱数据采集系统。该系统采用Altera公司Cyclone IV系列的FPGA芯片作为其微控制器,控制两片8通道的A/D芯片并行采集16通道的人体血液脉搏波光谱信号,采集到的数据在FPGA的控制下首先缓存在FPGA内部建立的乒乓RAM中,然后转存至外部SRAM芯片中,最后经USB总线传输至计算机。实验结果表明,在19 531 Hz的采样频率下,该系统能够高速并行采集16个通道的信号,重复性信噪比可达40 000∶1。此外,在该采样率下,系统可以采集到高信噪比的人体血液脉搏波信号,采集速度能够达到每秒305幅光谱图。该系统满足近红外无创伤血液成分检测仪器对于光谱数据采集系统的基本要求。该研究的主要创新点为将FPGA应用于近红外无创伤血液成分检测仪器的数据采集系统中,FPGA能够同时控制两片AD芯片进行16路人体血液脉搏波数据的高速并行采集,解决了单片机作为微控制器时无法实现多通道大量数据高速采集和储存的问题,使仪器的采集速度大大加快;同时使用FPGA内部资源建立乒乓RAM进行数据的缓冲,实现了不同位数数据从AD芯片到SRAM芯片的无缝连续传输。     

通量可控的双壁碳纳米管水分子泵

以双壁碳纳米管作为基本单元设计了一种新型纳米机械水泵, 其内管固定作为水分子通道, 外管做活塞式轴向运动. 分子动力学计算表明, 水分子净通量及管内水分子电偶极矩分布均与外管运动速率有强烈耦合效应. 该设计可以实现水分子的高效单向运输, 且输运效率可以通过外管活塞运动的速率进行调控. 这些发现可为未来实用纳米分子泵器件的设计提供新的思路.     

基于宽表面等离子体吸收带纳米银膜的制备及其SERS活性研究

在恒温条件下,采用静电自组装技术在玻璃表面制备了一种具有宽等离子吸收带的纳米银膜。使用扫描电镜(SEM)观察其表面形貌发现该纳米银膜表面由粒径为18～200 nm的纳米球组成。同时从紫外可见光谱检测结果发现该纳米银膜在400～850 nm间有较宽的等离子吸收带。分别以强荧光分子(结晶紫)和生物大分子(健康人血清)作为探针分子,在近红外激发光(785 nm)下检测出了质量较好的SERS光谱。同时,分析了该纳米银膜对两种分子检测的重复性。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.