Two-laser, large-field hyperspectral microarray scanner for the analysis of multicolor microarrays

We describe the development and operation of a two-laser, large-field hyperspectral scanner for analysis of multicolor genotyping microarrays. In contrast to confocal microarray scanners, in which wavelength selectivity is obtained by positioning band-pass filters in front of a photomultiplier detector, hyperspectral microarray scanners collect the complete visible emission spectrum from the labeled microarrays. Hyperspectral scanning permits discrimination of multiple spectrally overlapping fluorescent labels with minimal use of optical filters, thus offering important advantages over standard filter-based multicolor microarray scanners. The scanner uses two-sided oblique line illumination of microarrays. Two lasers are used for the excitation of dyes in the visible and near-infrared spectral regions. The hyperspectral scanner was evaluated with commercially available two-color calibration slides and with in-house-printed four-color microarrays containing dyes with spectral properties similar to their commercial genotyping array counterparts.     

The AX-PET demonstrator—Design, construction and characterization

Axial PET is a novel geometrical concept for Positron Emission Tomography (PET), based on layers of long scintillating crystals axially aligned with the bore axis. The axial coordinate is obtained from arrays of wavelength shifting (WLS) plastic strips placed orthogonally to the crystals. This article describes the design, construction and performance evaluation of a demonstrator set-up which consists of two identical detector modules, used in coincidence. Each module comprises 48 LYSO crystals of 100 mm length and 156 WLS strips. Crystals and strips are readout by Geiger-mode Avalanche Photo Diodes (G-APDs). The signals from the two modules are processed by fully analog front-end electronics and recorded in coincidence by a VME-based data acquisition system. Measurements with point-like ²²Na sources, with the modules used both individually and in coincidence mode, allowed for a complete performance evaluation up to the focal plane reconstruction of point sources. The results obtained are in good agreement with expectations and proved the set-up to be ready for the next evaluation phase with PET phantoms filled with radiotracers.     

Spectral characterization of a color scanner by adaptive estimation

A new method of spectral characterization for color scanners by the use of adaptive estimation is proposed. It deals with estimation of high-dimensional reflectance vectors from low-dimensional scanner response vectors when the scanner departs from linearity. We first investigate the spectral linearity of the scanner, and then estimate the spectral reflectance adaptively based on the local statistics of a set of neighboring training samples. As the proposed characterization method does not utilize the mathematically recovered spectral responsivity, its inherent inaccuracy is not critical to the spectral characterization. Experimental results showed significant advantage of adaptive estimation when compared with other methods.     

Development of a HTS magnet and application to a beam scanner

A solenoid magnet using high-temperature superconductor tape was designed, fabricated, and tested for its suitability as beam scanner. After successful cooling tests, the magnet performance was studied using DC and AC currents. With DC current the magnet was successfully operated as mirror coils for a 2.45 GHz ECR ion source. The coils could be operated at 100 A and frequencies above 1 Hz. The installation of iron pole pieces and return yokes, enabled us to generate fields in excess of 2 T at 197 A DC. In AC mode this magnet can be operated in the ranges of 0.14–1.73 and 1.22–1.67 T at frequencies of 0.05 and 0.25 Hz, respectively.     

Spectral characterization of a color scanner based on optimized adaptive estimation

A scanner characterization method is proposed to estimate spectral reflectance from scanner responses by using an optimized adaptive estimation method. In contrast to our previous study [J. Opt. Soc. Am. A21, 1125 (2004)], this method considers the weighting of training samples. It is demonstrated that the color accuracy of this method is only slightly affected by the number of training samples and can provide more accurate reflectance estimation.     

Design of a MEMS acoustical beamforming sensor microarray

This paper describes the design methodology for a microelectromechanical systems (MEMS)-based acoustical beamforming sensor microarray. The proposed acoustical array offers the potential of controlled directional sensitivity with constant beamwidth when used in conjunction with the appropriate digital signal processor. The array has been designed for use in a hearing instrument with a digital beamsteering engine to provide controlled directional sensitivity and constant beamwidth over the audio frequency range to improve speech intelligibility in noisy and reverberant environments. A MEMS-based packaging solution that allows the sensor array to be mounted in the ear canal is also described. The MEMS sensor-package interface features microspring contacts that enable low impedance connectivity between the sensor array and the related microelectronics. This allows the array to be easily removed for cleaning or replacement purposes.     

Visible reflectance hyperspectral imaging: characterization of a noninvasive,in vivo system for determining tissue perfusion

We characterize a visible reflectance hyperspectral imaging system for noninvasive, in vivo, quantitative analysis of human tissue in a clinical environment. The subject area is illuminated with a quartz-tungsten-halogen light source, and the reflected light is spectrally discriminated by a liquid crystal tunable filter (LCTF) and imaged onto a silicon charge-coupled device detector. The LCTF is continuously tunable within its useful visible spectral range (525-725 nm) with an average spectral full width at half-height bandwidth of 0.38 nm and an average transmittance of 10.0%. A standard resolution target placed 5.5 ft from the system results in a field of view with a 17-cm diameter and an optimal spatial resolution of 0.45 mm. The measured reflectance spectra are quantified in terms of apparent absorbance and formatted as a hyperspectral image cube. As a clinical example, we examine a model of vascular dysfunction involving both ischemia and reactive hyperemia during tissue reperfusion. In this model, spectral images, based upon oxyhemoglobin and deoxyhemoblobin signals in the 525-645-nm region, are deconvoluted using a multivariate least-squares regression analysis to visualize the spatial distribution of the percentages of oxyhemoglobin and deoxyhemoglobin in specific skin tissue areas.     

Active DLP hyperspectral illumination: a noninvasive, in vivo, system characterization visualizing tissue oxygenation at near video rates

We report use of a novel hyperspectral imaging system utilizing digital light processing (DLP) technology to noninvasively visualize in vivo tissue oxygenation during surgical procedures. The system's novelty resides in its method of illuminating tissue with precisely predetermined continuous complex spectra. The Texas Instruments digital micromirror device, DMD, chip consisting of 768 by 1024 mirrors, each 16 μm square, can be switched between two positions at 12.5 kHz. Switching the appropriate mirrors controls the intensity of light illuminating the tissue as a function of wavelength, active spectral illumination. Meaning, the tissue can be illuminated with a different spectrum of light within 80 μs. Precisely, predetermined spectral illumination penetrates into patient tissue, its chemical composition augments the spectral properties of the light, and its reflected spectra are detected and digitized at each pixel detector of a silicon charge-coupled device, CCD. Using complex spectral illumination, digital signal processing and chemometric methods produce chemically relevant images at near video rates. Specific to this work, tissue is illuminated spectrally with light spanning the visible electromagnetic spectrum (380 to 780 nm). Spectrophotometric images are detected and processed visualizing the percentage of oxyhemoglobin at each pixel detector and presented continuously, in real time, at 3 images per second. As a proof of principle application, kidneys of four live anesthetized pigs were imaged before, during, and after renal vascular occlusion. DLP Hyperspectral Imaging with active spectral illumination detected a 64.73 ± 1.5% drop in the oxygenation of hemoglobin within 30 s of renal arterial occlusion. Producing chemically encoded images at near video rate, time-resolved hyperspectral imaging facilitates monitoring renal blood flow during animal surgery and holds considerable promise for doing the same during human surgical interventions.     

Design and characterization of a photometer-colorimeter standard

A photometer and tristimulus colorimeter has been developed at the National Institute of Standards and Technology (NIST) to realize a color scale. A novel construction was developed to implement the spectral-responsivity-based scale with small uncertainty. The new device can be used as a reference illuminance and luminance meter as well. Temperature-controlled filter combinations, with 5-8 layers in one package, are used to match the responsivity of a silicon tunnel-trap detector to the CIE color-matching functions with small spectral mismatch values (f1'). Design considerations to extend the tunnel-trap detector with replaceable single and double apertures and changeable filter combinations are described. The design and fabrication of the filter packages and the dependence of the f1' values on the thickness of the filter layers are discussed. The colorimeter was characterized for angular, spatial, and spectral responsivity. An improved preamplifier can convert current to voltage in an 11-decade dynamic range with 0.01% uncertainty.     

Design of a MEMS discretized hyperbolic paraboloid geometry ultrasonic sensor microarray

Design of a discretized hyperbolic paraboloid geometry beamforming array of capacitive micromachined ultrasonic transducers (CMUT) has been presented. The array can intrinsically provide a broadband constant beamwidth beamforming capability without any microelectronic signal processing. A mathematical model has been developed and verified to characterize the array response. A design methodology has been presented that enables determination of the array's physical dimensions and CMUT modeling in a straightforward manner. Developed methodology has been used to design two discretized hyperbolic paraboloid geometry beamforming CMUT arrays: one in the 2.3 MHz to 5.2 MHz frequency range and another in the 113 kHz to 167 kHz frequency range. CMUTs have been designed using a cross-verification method that involves lumped element modeling, 3-D electromechanical finite element analysis (FEA), and microfabrication simulation. The developed array has the potential to be used in real-time automotive collision-avoidance applications, medical diagnostic imaging and therapeutic applications, and industrial sensing.     

Design,optimization, and construction of a dc SQUID with complete flux transformer circuits

The design of a complete dc SQUID with a flux transformer input circuit is discussed. The flux coupling circuits introduce a substantial capacitance across the SQUID and give rise to many resonances which may couple strongly to the SQUID dynamics. Both effects lead to multiple modes in the SQUID dynamics and consequently to excess noise. For a low-noise SQUID with smooth characteristics, our analysis and practical considerations suggest signal coupling via an intermediary transformer. This method allows simultaneous optimization of the SQUID parameters, minimizing the parasitic capacitance, control over the resonances, and good inductance matching to practical magnetometer coils. A model is developed to optimize the structure: it describes the whole circuit with the help of a suitably modified autonomous SQUID, provided that the system is free from multiple modes due to resonances or large parasitic capacitance. Following these design principles, we have built a dc SQUID, primarily for use in biomagnetic research, but also well suited for other applications. The fabrication of the SQUID and the high-quality electronics especially suitable for multiple-SQUID devices is presented. The SQUIDs showed smooth characteristics, and the lowest measured noise of our complete SQUID is % MathType!MTEF!2!1!+-% feaafeart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaaGymaiaac6% cacaaIZaGaey41aqRaaGymaiaaicdadaahaaWcbeqaaiabgkHiTiaa% iAdaaaGccqqHMoGrdaWgaaWcbaGaaGimaiaac+caaeqaaOWaaOaaae% aacaWGibGaamOEaaWcbeaaaaa!428B!$1.3 \times 10^{ - 6} \Phi _{0/} \sqrt {Hz} $, indicating the success of the design.     

机器人-三维扫描系统联合扫描及其工业应用

一种由便携式三维激光扫描仪和六自由度工业机器人组成的机器人-三维扫描系统可以多角度多方位的获取物体表面的三维信息.针对激光扫描系统和机器人的两种不同组合方式,提出了一种新的确定机器人和激光扫描系统位姿关系的标定方法.该方法使用半径已知的球体作为参照工具,利用扫描系统投射出的线激光与球体的相交线拟合圆来恢复球心以及扫描整个球面拟合球心分别标定了扫描仪与机器人的旋转和平移关系,从而使机器人能够与扫描仪一起完成扫描任务.同时,将该机器人-三维扫描系统应用于工业加工中,可以实现在线测量、加工一体化.使用此系统成功地进行了吉他扫描,并利用得到的扫描数据对吉他进行了精确的边缘加工.实验结果证明,该机器人-三维扫描系统具有测量精度高及稳定性好的特点.     

Design,construction and performance of a liquid xenon and liquid argon ionization chamber

We have constructed an ionization chamber for liquid xenon and liquid argon and have conducted studies of initial ion-electron recombination. Using a 392 keV ¹¹³Sn source, we find in xenon a charge collection of (90±5)% at an electric drift field of 1.6 kV/cm and (10±3)% at 10 V/cm. In argon we collect (78±5)% of the charge in a field of 1.6 kV/cm. We have developed a method for measuring the concentration of electronegative impurities in the detector liquid. The purity of the liquid was always better than 2 ppb O₂ equivalent. Under these conditions, the energy resolution observed with either liquid in the detector is (12±1)% FWHM at 380 keV in an electric drift field of 1.8 kV/cm for argon and 1.6 kV/cm for xenon. This appears to be a fundamental limit imposed by the statistics of delta electron production.     

Fabrication, characterization, and application of a composite adsorbent for simultaneous removal of arsenic and fluoride

Coexisting arsenic (As) and fluoride (F) in groundwater poses severe health risks worldwide. Highly efficient simultaneous removal of As and F is therefore of great urgency and high priority. The purpose of this study was to fabricate a novel composite adsorbent and explore the mechanism for concurrent removal of As(V) and F at the molecular level. This bifunctional adsorbent with titanium and lanthanum oxides impregnated on granular activated carbon (TLAC) exhibits a pronounced As(V) and F adsorption capacity over commercially available iron- and aluminum-based adsorbents for synthetic and real contaminated groundwater samples. Synchrotron-based X-ray microfluorescence analysis demonstrates that La and Ti were homogeneously distributed on TLAC. Extended X-ray absorption fine structure spectroscopic results suggest that As(V) formed bidentate binuclear surface complex as evidenced by an averaged Ti-As bond distance of 3.34 ? in the presence of F. Adsorption tests and Fourier transform infrared spectroscopy analysis indicate that F was selectively adsorbed on lanthanum oxides. The surface configurations constrained with the spectroscopic results were formulated in the charge distribution multisite complexation model to describe the competitive adsorption behaviors of As(V) and F. The results of this study indicate that TLAC could be used as an effective adsorbent for simultaneous removal of As(V) and F.     

便携式激光扫描仪中电磁定位系统的设计

为了实现便携式激光扫描仪的空间定位,根据三轴磁阻传感器的工作原理,设计了一种电磁定位系统.重点分析了硬件电路的设计,包括功放电路、传感器接收电路、A/D接口电路等.电路采用TI公司的TMS320F281作为微处理器,通过功放电路对正弦信号进行放大,同时对传感器三路模拟信号进行采样处理.系统可操作性强,测量精度高,可实现对磁场空间任意一点的磁场强度和方向的检测,有广阔的应用前景.     

Preparation, characterization, and electrochemical application of mesoporous copper oxide

Mesoporous CuO was successfully synthesized via thermal decomposition of CuC₂O₄ precursors. These products had ring-like morphology, which was made up of nanoparticles with the average diameter of 40 nm. The electrochemical experiments showed that the mesoporous CuO decreased the overvoltage of the electrode and increased electron transference in the measurement of dopamine.     

寡胺-葡聚糖类阳离子化合物合成及其在基因转染中的应用

应用氧化葡聚糖与精胺通过还原胺法反应,制备了聚阳离子非病毒基因载体葡聚糖-寡胺化合物;用红外光谱测定仪、核磁共振波谱仪、紫外光谱仪,激光纳米粒度测定仪、透射电子显微镜进行了表征.证实了该载体为葡聚糖-精胺化合物DSP.其平均粒径为170nm,Zeta电位为+31.1mV,镜下呈园球形状.将载体DSP与pCMV-GFP的质粒DNA以8:1(N/P)组成复合物时,对SMMC-7721人肝癌细胞进行体外转染,转染效率高于阳性对照组transfectine 2000,为31.1%.实验表明该材料有望成为临床的非病毒基因载体.     

Principles of a nanoscale DNA scanner

A nanofluidic device for the routine stretching of single DNA molecules was hypothesised and tested. The device consists of an entrance channel leading to a post-field preceding an elongational flow field. The device facilitates each molecule's coil-to-stretch transition, counteracts its entropic recoil, and presents a stream of moving stretched molecules for detailed single-molecule time-of-flight measurements. The physics of DNA stretching was explored in a device where there was a juxtaposition of hexagonal upright post arrays with lithographically defined elongational flow fields.